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Sample records for group iv phospholipase

  1. Group XV phospholipase A2, a lysosomal phospholipase A2

    PubMed Central

    Shayman, James A.; Kelly, Robert; Kollmeyer, Jessica; He, Yongqun; Abe, Akira

    2010-01-01

    A phospholipase A2 was identified from MDCK cell homogenates with broad specificity toward glycerophospholipids including phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol. The phospholipase has the unique ability to transacylate short chain ceramides. This phospholipase is calcium-independent, localized to lysosomes, and has an acidic pH optimum. The enzyme was purified from bovine brain and found to be a water-soluble glycoprotein consisting of a single peptide chain with a molecular weight of 45 kDa. The primary structure deduced from the DNA sequences is highly conserved between chordates. The enzyme was named lysosomal phospholipase A2 (LPLA2) and subsequently designated group XV phospholipase A2. LPLA2 has 49 percent of amino acid sequence identity to lecithin cholesterol acyltransferase and is a member of the αβ-hydrolase superfamily. LPLA2 is highly expressed in alveolar macrophages. A marked accumulation of glycerophospholipids and extensive lamellar inclusion bodies, a hallmark of cellular phospholipidosis, is observed in alveolar macrophages in LPLA2−/− mice. This defect can also be reproduced in macrophages that are exposed to cationic amphiphilic drugs such as amiodarone. In addition, older LPLA2−/− mice develop a phenotype similar to human autoimmune disease. These observations indicate that LPLA2 may play a primary role in phospholipid homeostasis, drug toxicity, and host defense. PMID:21074554

  2. Anti-CD3 and concanavalin A-induced human T cell proliferation is associated with an increased rate of arachidonate-phospholipid remodeling. Lack of involvement of group IV and group VI phospholipase A2 in remodeling and increased susceptibility of proliferating T cells to CoA-independent transacyclase inhibitor-induced apoptosis.

    PubMed

    Boilard, E; Surette, M E

    2001-05-18

    In this study arachidonate-phospholipid remodeling was investigated in resting and proliferating human T lymphocytes. Lymphocytes induced to proliferate with either the mitogen concanavalin A or with anti-CD3 (OKT3) in combination with interleukin 2 (OKT3/IL-2) showed a greatly accelerated rate of [3H]arachidonate-phospholipid remodeling compared with resting lymphocytes or with lymphocytes stimulated with OKT3 or IL-2 alone. The concanavalin A-stimulated cells showed a 2-fold increase in the specific activity of CoA-independent transacylase compared with unstimulated cells, indicating that this enzyme is inducible. Stimulation with OKT3 resulted in greatly increased quantities of the group VI calcium-independent phospholipase A2 but not of the quantity of group IV cytosolic phospholipase A2. However, group IV phospholipase A2 became phosphorylated in OKT3-stimulated cells, as determined by decreased electrophoretic mobility. Incubation of cells with the group VI phospholipase A2 inhibitor, bromoenol lactone, or the dual group IV/group VI phospholipase A2 inhibitor, methyl arachidonyl fluorophosphonate, did not block arachidonate-phospholipid remodeling resting or proliferating T cells, suggesting that these phospholipases A2 were not involved in arachidonate-phospholipid remodeling. The incubation of nonproliferating human lymphocytes with inhibitors of CoA-independent transacylase had little impact on cell survival. In contrast, OKT3/IL-2-stimulated T lymphocytes were very sensitive to apoptosis induced by CoA-independent transacylase inhibitors. Altogether these results indicate that increased arachidonate-phospholipid remodeling is associated with T cell proliferation and that CoA-independent transacylase may be a novel therapeutic target for proliferative disorders.

  3. IVS Working Group 4: VLBI Data Structures

    NASA Technical Reports Server (NTRS)

    Gipson, John

    2010-01-01

    In 2007 the IVS Directing Board established IVS Working Group 4 on VLBI Data Structures. This note discusses the current VLBI data format, goals for a new format, the history and formation of the Working Group, and a timeline for the development of a new VLBI data format.

  4. Collagen type IV stimulates an increase in intracellular Ca2+ in pancreatic acinar cells via activation of phospholipase C.

    PubMed Central

    Somogyi, L; Lasić, Z; Vukicević, S; Banfić, H

    1994-01-01

    Intracellular Ca2+ responses to extracellular matrix molecules were studied in suspensions of pancreatic acinar cells loaded with Fura-2. Collagen type I, laminin, fibrinogen and fibronectin were unable to raise cytosolic free Ca2+ concentration ([Ca2+]i), whereas collagen type IV, at concentrations from 5 to 50 micrograms/ml, significantly increased it. The effect of collagen type IV was not due to possible contamination with type-I transforming growth factor beta or plasminogen, as neither of these agents was able to increase [Ca2+]i. Using highly specific mass assays, concentrations of inositol lipids, 1,2-diacylglycerol (DAG) and Ins(1,4,5) P3 were measured in pancreatic acinar cells stimulated with collagen type IV. A decrease in the concentrations of PtdIns(4,5) P2 and PtdIns4 P with a concomitant increase in the concentrations of DAG and InsP3 mass were observed, showing that collagen type IV increases [Ca2+]i by activation of phospholipase C. The observed [Ca2+]i signals had two components, the first resulting from Ca2+ release from the intracellular stores, and the second resulting from Ca2+ flux from the extracellular medium through the verapamil-insensitive channels. A tyrosine kinase inhibitor (tyrphostine) was able to block inositol lipid signalling caused by collagen type IV, which together with the insensitivity of this pathway to cholera toxin and pertussis toxin or to preactivation of protein kinase C, the longer duration of the increase in [Ca2+]i and a longer lag period needed for observation of increases in DAG and InsP3 concentration with collagen type IV than with carbachol (50 mM) suggest that activation of phospholipase C by collagen type IV is caused by tyrosine kinase activation. Inositol lipid signalling and increases in [Ca2+]i were also observed with Arg-Gly-Asp (RGD)-containing peptide but not with Arg-Asp-Gly (RDG)-containing peptide. Collagen type IV and RGD-containing peptide, but not carbachol, competed in increasing [Ca2+]i and

  5. Giant piezoelectricity of monolayer group IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Fei, Ruixiang; Li, Wenbin; Li, Ju; Yang, Li

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M =Sn or Ge, X =Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique ``puckered'' C2v symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  6. Inhibitory Effect of Orientin on Secretory Group IIA Phospholipase A2.

    PubMed

    Bae, Jong-Sup

    2015-08-01

    It is well known that the expression level of secretory group IIA phospholipase A2 (sPLA2-IIA) is elevated in inflammatory diseases and lipopolysaccharide (LPS) upregulates the expression of sPLA2-IIA in human umbilical vein endothelial cells (HUVECs). Orientin, a C-glycosyl flavonoid, is known to have anxiolytic, anti-oxidative, and anti-inflammatory activity. Here, orientin was examined for its effects on the expression and activity of sPLA2-IIA in HUVECs and mouse. Prior treatment of cells or mouse with orientin inhibited LPS-induced expression and activity of sPLA2-IIA. And orientin suppressed the activation of cytosolic phospholipase A2 (cPLA2) and extracellular signal-regulated kinase (ERK) 1/2 by LPS. Therefore, these results suggest that orientin may inhibit LPS-mediated expression of sPLA2-IIA by suppression of cPLA2 and ERK 1/2.

  7. Head group specificity of phospholipase D isoenzymes from poppy seedlings (Papaver somniferum L.).

    PubMed

    Oblozinsky, M; Ulbrich-Hofmann, R; Bezakova, L

    2005-02-01

    The biocatalytical potential of two new phospholipase D (PLD) isoenzymes from poppy seedlings (Papaver somniferum L.), PLD-A and PLD-B, was examined by comparing their activities in phospholipid transformation. Both enzymes showed the same ratio in rates of hydrolysis [phosphatidylcholine (PC):phosphatidylglycerol (PG):phosphatidylserine:phosphatidylinositol = 1:0.5:0.3:0.1] and were inactive towards phosphatidylethanolamine (PE). PLD-A did not catalyze head group exchange whereas PLD-B showed a high transphosphatidylation potential in the conversion of PC into PG and PE. This enzyme also catalyzed the transesterification of octadecylphosphocholine into octadecylphosphoglycerol or octadecylphosphoethanolamine.

  8. OKT3-induced nephrotoxicity is associated with release of group II secretory phospholipase A2.

    PubMed

    Wever, P C; Roest, R W; Wolbink-Kamp, A M; Wolbink, G J; Weening, J J; Hack, C E; ten Berge, J M

    1996-10-01

    Administration of the murine IgG2a CD3 monoclonal antibody OKT3 exerts a transient nephrotoxic effect. Increased levels of group II secretory phospholipase A2 (sPLA2-II) might account for this nephrotoxicity as sPLA2-II induces the biosynthesis of prostaglandins, vasoactive lipid mediators that influence glomerular haemodynamics and renal function. Furthermore, extracellular phospholipases seem to be involved in proximal tubular cell injury. We studied plasma sPLA2-II levels in relation to circulating creatinine, tumour necrosis factor alpha, interleukin 6 and C-reactive protein levels in 15 renal allograft recipients receiving rejection treatment with OKT3. As a control group, we studied 15 renal allograft recipients receiving rejection treatment with methylprednisolone. A maximal fourfold increase in sPLA2-II levels was observed 48 h after the first OKT3 administration, preceded by increased tumour necrosis factor alpha and interleukin 6 levels and accompanied by increased C-reactive protein levels. Creatinine levels reached a maximal increase 72 h after initiation of treatment. During methylprednisolone treatment no increase in any of the studied parameters was observed. Thus, administration of OKT3 induces increased sPLA2-II levels, presumably via generation of cytokines. We hypothesize that sPLA2-II may contribute to the nephrotoxic effect of OKT3 by inducing vasoconstrictive prostaglandins and renal tubular cell injury.

  9. The dipeptidyl peptidase IV inhibitors vildagliptin and K-579 inhibit a phospholipase C: a case of promiscuous scaffolds in proteins

    PubMed Central

    Dutta, Mouparna; Ghosh, Anindya S.; Oda, Masataka; Venkatramani, Ravindra; Rao, Basuthkar J.; Dandekar, Abhaya M.; Goñi, Félix M.

    2015-01-01

    The long term side effects of any newly introduced drug is a subject of intense research, and often raging controversies. One such example is the dipeptidyl peptidase-IV (DPP4) inhibitor used for treating type 2 diabetes, which is inconclusively implicated in increased susceptibility to acute pancreatitis. Previously, based on a computational analysis of the spatial and electrostatic properties of active site residues, we have demonstrated that phosphoinositide-specific phospholipase C (PI-PLC) from Bacillus cereus is a prolyl peptidase using in vivo experiments. In the current work, we first report the inhibition of the native activity of PI-PLC by two DPP4 inhibitors - vildagliptin (LAF-237) and K-579. While vildagliptin inhibited PI-PLC at micromolar concentrations, K-579 was a potent inhibitor even at nanomolar concentrations. Subsequently, we queried a comprehensive, non-redundant set of 5000 human proteins (50% similarity cutoff) with known structures using serine protease (SPASE) motifs derived from trypsin and DPP4. A pancreatic lipase and a gastric lipase are among the proteins that are identified as proteins having promiscuous SPASE scaffolds that could interact with DPP4 inhibitors. The presence of such scaffolds in human lipases is expected since they share the same catalytic mechanism with PI-PLC. However our methodology also detects other proteins, often with a completely different enzymatic mechanism, that have significantly congruent domains with the SPASE motifs. The reported elevated levels of serum lipase, although contested, could be rationalized by inhibition of lipases reported here. In an effort to further our understanding of the spatial and electrostatic basis of DPP4 inhibitors, we have also done a comprehensive analysis of all 76 known DPP4 structures liganded to inhibitors till date. Also, the methodology presented here can be easily adopted for other drugs, and provide the first line of filtering in the identification of pathways that

  10. The dipeptidyl peptidase IV inhibitors vildagliptin and K-579 inhibit a phospholipase C: a case of promiscuous scaffolds in proteins.

    PubMed

    Chakraborty, Sandeep; Rendón-Ramírez, Adela; Ásgeirsson, Bjarni; Dutta, Mouparna; Ghosh, Anindya S; Oda, Masataka; Venkatramani, Ravindra; Rao, Basuthkar J; Dandekar, Abhaya M; Goñi, Félix M

    2013-01-01

    The long term side effects of any newly introduced drug is a subject of intense research, and often raging controversies. One such example is the dipeptidyl peptidase-IV (DPP4) inhibitor used for treating type 2 diabetes, which is inconclusively implicated in increased susceptibility to acute pancreatitis. Previously, based on a computational analysis of the spatial and electrostatic properties of active site residues, we have demonstrated that phosphoinositide-specific phospholipase C (PI-PLC) from Bacillus cereus is a prolyl peptidase using in vivo experiments. In the current work, we first report the inhibition of the native activity of PI-PLC by two DPP4 inhibitors - vildagliptin (LAF-237) and K-579. While vildagliptin inhibited PI-PLC at micromolar concentrations, K-579 was a potent inhibitor even at nanomolar concentrations. Subsequently, we queried a comprehensive, non-redundant set of 5000 human proteins (50% similarity cutoff) with known structures using serine protease (SPASE) motifs derived from trypsin and DPP4. A pancreatic lipase and a gastric lipase are among the proteins that are identified as proteins having promiscuous SPASE scaffolds that could interact with DPP4 inhibitors. The presence of such scaffolds in human lipases is expected since they share the same catalytic mechanism with PI-PLC. However our methodology also detects other proteins, often with a completely different enzymatic mechanism, that have significantly congruent domains with the SPASE motifs. The reported elevated levels of serum lipase, although contested, could be rationalized by inhibition of lipases reported here. In an effort to further our understanding of the spatial and electrostatic basis of DPP4 inhibitors, we have also done a comprehensive analysis of all 76 known DPP4 structures liganded to inhibitors till date. Also, the methodology presented here can be easily adopted for other drugs, and provide the first line of filtering in the identification of pathways that

  11. Inherited human group IVA cytosolic phospholipase A2 deficiency abolishes platelet, endothelial, and leucocyte eicosanoid generation

    PubMed Central

    Kirkby, Nicholas S.; Reed, Daniel M.; Edin, Matthew L.; Rauzi, Francesca; Mataragka, Stefania; Vojnovic, Ivana; Bishop-Bailey, David; Milne, Ginger L.; Longhurst, Hilary; Zeldin, Darryl C.; Mitchell, Jane A.; Warner, Timothy D.

    2016-01-01

    Eicosanoids are important vascular regulators, but the phospholipase A2 (PLA2) isoforms supporting their production within the cardiovascular system are not fully understood. To address this, we have studied platelets, endothelial cells, and leukocytes from 2 siblings with a homozygous loss-of-function mutation in group IVA cytosolic phospholipase A2 (cPLA2α). Chromatography/mass spectrometry was used to determine levels of a broad range of eicosanoids produced by isolated vascular cells, and in plasma and urine. Eicosanoid release data were paired with studies of cellular function. Absence of cPLA2α almost abolished eicosanoid synthesis in platelets (e.g., thromboxane A2, control 20.5 ± 1.4 ng/ml vs. patient 0.1 ng/ml) and leukocytes [e.g., prostaglandin E2 (PGE2), control 21.9 ± 7.4 ng/ml vs. patient 1.9 ng/ml], and this was associated with impaired platelet activation and enhanced inflammatory responses. cPLA2α-deficient endothelial cells showed reduced, but not absent, formation of prostaglandin I2 (prostacyclin; control 956 ± 422 pg/ml vs. patient 196 pg/ml) and were primed for inflammation. In the urine, prostaglandin metabolites were selectively influenced by cPLA2α deficiency. For example, prostacyclin metabolites were strongly reduced (18.4% of control) in patients lacking cPLA2α, whereas PGE2 metabolites (77.8% of control) were similar to healthy volunteer levels. These studies constitute a definitive account, demonstrating the fundamental role of cPLA2α to eicosanoid formation and cellular responses within the human circulation.—Kirkby, N. S., Reed, D. M., Edin, M. L., Rauzi, F., Mataragka, S., Vojnovic, I., Bishop-Bailey, D., Milne, G. L., Longhurst, H., Zeldin, D. C., Mitchell, J. A., Warner, T. D. Inherited human group IVA cytosolic phospholipase A2 deficiency abolishes platelet, endothelial, and leucocyte eicosanoid generation. PMID:26183771

  12. Expression of group XIIA phospholipase A2 in human digestive organs.

    PubMed

    Peuravuori, Heikki; Kollanus, Sinikka; Nevalainen, Timo J

    2014-12-01

    Cellular distribution of group XIIA phospholipase A2 (GXIIA PLA2) was studied in human digestive organs by immunohistochemistry. GXIIA PLA2 protein was detected in epithelial cells of normal gastrointestinal tract, gallbladder and pancreatic acinar cells. The GXIIA PLA2 protein was evenly distributed in the cytoplasm in contrast to secretory granular distribution of GIB PLA2 and GIIA PLA2 in pancreatic acinar cells and small intestinal Paneth cells respectively. Epithelial cells of intestinal glands in Crohn's disease and ulcerative colitis expressed abundant GXIIA PLA2 , whereas inflammatory cells were devoid of the enzyme protein. Tumour cells in colonic adenomas and carcinomas and pancreatic ductogenic carcinomas expressed GXIIA PLA2 protein at varying intensity levels. The putative functions of GXIIA PLA2 remain to be investigated and its role in healthy and diseased digestive organs can only be speculated on at present.

  13. Point of care testing of phospholipase A2 group IIA for serological diagnosis of rheumatoid arthritis

    NASA Astrophysics Data System (ADS)

    Liu, Nathan J.; Chapman, Robert; Lin, Yiyang; Mmesi, Jonas; Bentham, Andrew; Tyreman, Matthew; Abraham, Sonya; Stevens, Molly M.

    2016-02-01

    Secretory phospholipase A2 group IIA (sPLA2-IIA) was examined as a point of care marker for determining disease activity in rheumatoid (RA) and psoriatic (PsA) arthritis. Serum concentration and activity of sPLA2-IIA were measured using in-house antibodies and a novel point of care lateral flow device assay in patients diagnosed with varying severities of RA (n = 30) and PsA (n = 25) and found to correlate strongly with C-reactive protein (CRP). Levels of all markers were elevated in patients with active RA over those with inactive RA as well as both active and inactive PsA, indicating that sPLA2-IIA can be used as an analogue to CRP for RA diagnosis at point of care.Secretory phospholipase A2 group IIA (sPLA2-IIA) was examined as a point of care marker for determining disease activity in rheumatoid (RA) and psoriatic (PsA) arthritis. Serum concentration and activity of sPLA2-IIA were measured using in-house antibodies and a novel point of care lateral flow device assay in patients diagnosed with varying severities of RA (n = 30) and PsA (n = 25) and found to correlate strongly with C-reactive protein (CRP). Levels of all markers were elevated in patients with active RA over those with inactive RA as well as both active and inactive PsA, indicating that sPLA2-IIA can be used as an analogue to CRP for RA diagnosis at point of care. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08423g

  14. Oxidation Resistance of Monolayer Group-IV Monochalcogenides.

    PubMed

    Guo, Yu; Zhou, Si; Bai, Yizhen; Zhao, Jijun

    2017-03-21

    Ridged, orthorhombic two-dimensional (2D) group-V elemental and group IV-VI compound analogues of phosphorene provide a versatile platform for nanoelectronics, optoelectronics, and clean energy. However, phosphorene is vulnerable to oxygen in ambient air, which is a major obstacle for its applications. Regarding this issue, here we explore the oxidation behavior of monolayer group-IV monochalcogenides (GeS, GeSe, SnS, and SnSe), in comparison to that of phosphorene and arsenene by first-principles calculations. We find superior oxidation resistance of the monolayer group-IV monochalcogenides, with activation energies for the chemisorption of O2 on the 2D sheets in the range of 1.26-1.60 eV, about twice of the values of phosphorene and arsenene. The distinct oxidation behaviors of monolayer group-IV monochalcogenides and group-V phosphorene analogues originate from their different bond natures. Moreover, the chemisorption of a moderate amount of oxygen atoms does not severely deteriorate the electronic band structures of the monolayer group-IV monochalcogenides. These results shine light on the utilization of the monolayer group-IV monochalcogenides for next-generation 2D electronics and optoelectronics with high performance and stability.

  15. Group IV photonics for the mid infrared

    NASA Astrophysics Data System (ADS)

    Soref, Richard

    2013-02-01

    This paper outlines the challenges and benefits of applying silicon-based photonic techniques in the 2 to 5 μm midinfrared (MIR) wavelength range for chem.-bio-physical sensing, medical diagnostics, industrial process control, environmental monitoring, secure communications, Ladar, active imaging, and high-speed communications at 2 μm. Onchip passive and active components, mostly waveguided, will enable opto-electronic CMOS or BiCMOS integrated "circuits" for system-on-a-chip applications such as spectroscopy and lab-on-a-chip. Volume manufacture in a silicon foundry is expected to yield low-cost (or even disposable) chips with benefits in size-weight-power and ruggedness. This is "long-wavelength optoelectronic integration on silicon" which we call LIOS. Room temperature operation appears feasible, albeit with performance compromises at 4 to 5 μm. In addition to the electronics layer (which may include RF wireless), a 3-D LIOS chip can include several inter-communicating layers utilizing the photonic, plasmonic, photoniccrystal and opto-electro-mechanical technologies. The LIOS challenge can be met by (1) discovering new physics, (2) employing "new" IV and III-V alloys, (3) scaling-up and modifying telecom components, and (4) applying nonlinearoptical wavelength conversion in some cases. This paper presents proposals for MIR chip spectrometers employing frequency-comb and Ge blackbody sources. Active heterostructures employing Si, Ge, SiGe, GeSn and SiGeSn are key for laser diodes, photodetectors, LEDs, switches, amplifiers, and modulators that provide totally monolithic foundry integration, while numerous III-V semiconductor MIR devices within the InGaAsSb and InGaAsP families offer practical hybrid integration on Si PICs. Interband cascade and quantum cascade lasers on Ge waveguides are important in this context.

  16. Bacterial phospholipases C.

    PubMed Central

    Titball, R W

    1993-01-01

    A variety of pathogenic bacteria produce phospholipases C, and since the discovery in 1944 that a bacterial toxin (Clostridium perfringens alpha-toxin) possessed an enzymatic activity, there has been considerable interest in this class of proteins. Initial speculation that all phospholipases C would have lethal properties has not been substantiated. Most of the characterized enzymes fall into one of four groups of structurally related proteins: the zinc-metallophospholipases C, the sphingomyelinases, the phosphatidylinositol-hydrolyzing enzymes, and the pseudomonad phospholipases C. The zinc-metallophospholipases C have been most intensively studied, and lethal toxins within this group possess an additional domain. The toxic phospholipases C can interact with eukaryotic cell membranes and hydrolyze phosphatidylcholine and sphingomyelin, leading to cell lysis. However, measurement of the cytolytic potential or lethality of phospholipases C may not accurately indicate their roles in the pathogenesis of disease. Subcytolytic concentrations of phospholipase C can perturb host cells by activating the arachidonic acid cascade or protein kinase C. Nonlethal phospholipases C, such as the Listeria monocytogenes PLC-A, appear to enhance the release of the organism from the host cell phagosome. Since some phospholipases C play important roles in the pathogenesis of disease, they could form components of vaccines. A greater understanding of the modes of action and structure-function relationships of phospholipases C will facilitate the interpretation of studies in which these enzymes are used as membrane probes and will enhance the use of these proteins as models for eukaryotic phospholipases C. PMID:8336671

  17. Group IVA phospholipase A2 participates in the progression of hepatic fibrosis.

    PubMed

    Ishihara, Keiichi; Miyazaki, Akira; Nabe, Takeshi; Fushimi, Hideaki; Iriyama, Nao; Kanai, Shiho; Sato, Takashi; Uozumi, Naonori; Shimizu, Takao; Akiba, Satoshi

    2012-10-01

    Group IVA phospholipase A2 (IVA-PLA2) is an enzyme that intiates the arachidonic acid pathway and plays an important role in inflammation. We demonstrate that IVA-PLA2 deficiency suppresses lipid deposition in the liver, which was induced by administration of a high-fat and -cholesterol diet (HFCD) for 16 wk in mice. Herein, we performed 2-dimensional gel-based comparative proteomics to further define the suppressive effect of IVA-PLA2 deficiency on fatty liver formation. In comparisons among 4 groups, wild-type (WT)/normal diet (ND), IVA-PLA2-deficient knockout (KO)/ND, WT/HFCD, and KO/HFCD, 4 proteins, 3 of which are associated with hepatic fibrosis, were identified as molecules, of which altered expression by HFCD was suppressed in KO mice compared to WT mice. Therefore, we assessed the effect of IVA-PLA2 deficiency on hepatic fibrosis induced by HFCD or carbon tetrachloride (CCl4) in mouse models. Biochemical and histological analyses revealed that IVA-PLA2 deficiency markedly reduced overall collagen accumulation in the liver of HFCD- and CCl4-derived mouse models. We found that IVA-PLA2 deficiency prevented activation of hepatic stellate cells and infiltration of F4/80-positive macrophages without affecting other immunocytes such as CD8+ lymphocytes and natural killer cells. In summary, IVA-PLA2 deficiency attenuates not only lipid deposition in the liver but also hepatic fibrosis formation.

  18. Enhanced Phospholipase A2 Group 3 Expression by Oxidative Stress Decreases the Insulin-Degrading Enzyme

    PubMed Central

    Yui, Daishi; Nishida, Yoichiro; Nishina, Tomoko; Mogushi, Kaoru; Tajiri, Mio; Ishibashi, Satoru; Ajioka, Itsuki; Ishikawa, Kinya; Mizusawa, Hidehiro; Murayama, Shigeo; Yokota, Takanori

    2015-01-01

    Oxidative stress has a ubiquitous role in neurodegenerative diseases and oxidative damage in specific regions of the brain is associated with selective neurodegeneration. We previously reported that Alzheimer disease (AD) model mice showed decreased insulin-degrading enzyme (IDE) levels in the cerebrum and accelerated phenotypic features of AD when crossbred with alpha-tocopherol transfer protein knockout (Ttpa-/-) mice. To further investigate the role of chronic oxidative stress in AD pathophysiology, we performed DNA microarray analysis using young and aged wild-type mice and aged Ttpa-/- mice. Among the genes whose expression changed dramatically was Phospholipase A2 group 3 (Pla2g3); Pla2g3 was identified because of its expression profile of cerebral specific up-regulation by chronic oxidative stress in silico and in aged Ttpa-/- mice. Immunohistochemical studies also demonstrated that human astrocytic Pla2g3 expression was significantly increased in human AD brains compared with control brains. Moreover, transfection of HEK293 cells with human Pla2g3 decreased endogenous IDE expression in a dose-dependent manner. Our findings show a key role of Pla2g3 on the reduction of IDE, and suggest that cerebrum specific increase of Pla2g3 is involved in the initiation and/or progression of AD. PMID:26637123

  19. Human group IIA secretory phospholipase A2 induces neuronal cell death via apoptosis.

    PubMed

    Yagami, Tatsurou; Ueda, Keiichi; Asakura, Kenji; Hata, Satoshi; Kuroda, Takayuki; Sakaeda, Toshiyuki; Takasu, Nobuo; Tanaka, Kazushige; Gemba, Takefumi; Hori, Yozo

    2002-01-01

    Expression of group IIA secretory phospholipase A2 (sPLA2-IIA) is documented in the cerebral cortex (CTX) after ischemia, suggesting that sPLA2-IIA is associated with neurodegeneration. However, how sPLA2-IIA is involved in the neurodegeneration remains obscure. To clarify the pathologic role of sPLA2-IIA, we examined its neurotoxicity in rats that had the middle cerebral artery occluded and in primary cultures of cortical neurons. After occlusion, sPLA2 activity was increased in the CTX. An sPLA2 inhibitor, indoxam, significantly ameliorated not only the elevated activity of the sPLA2 but also the neurodegeneration in the CTX. The neuroprotective effect of indoxam was observed even when it was administered after occlusion. In primary cultures, sPLA2-IIA caused marked neuronal cell death. Morphologic and ultrastructural characteristics of neuronal cell death by sPLA2-IIA were apoptotic, as evidenced by condensed chromatin and fragmented DNA. Before apoptosis, sPLA2-IIA liberated arachidonic acid (AA) and generated prostaglandin D2 (PGD2), an AA metabolite, from neurons. Indoxam significantly suppressed not only AA release, but also PGD2 generation. Indoxam prevented neurons from sPLA2-IIA-induced neuronal cell death. The neuroprotective effect of indoxam was observed even when it was administered after sPLA2-IIA treatment. Furthermore, a cyclooxygenase-2 inhibitor significantly prevented neurons from sPLA2-IIA-induced PGD2 generation and neuronal cell death. In conclusion, sPLA2-IIA induces neuronal cell death via apoptosis, which might be associated with AA metabolites, especially PGD2. Furthermore, sPLA2 contributes to neurodegeneration in the ischemic brain, highlighting the therapeutic potential of sPLA2-IIA inhibitors for stroke.

  20. Molecular determinants of bacterial sensitivity and resistance to mammalian Group IIA phospholipase A2.

    PubMed

    Weiss, Jerrold P

    2015-11-01

    Group IIA secretory phospholipase A2 (sPLA(2)-IIA) of mammalian species is unique among the many structurally and functionally related mammalian sPLA(2) in their high net positive charge and potent (nM) antibacterial activity. Toward the Gram-positive bacteria tested thus far, the global cationic properties of sPLA(2)-IIA are necessary for optimal binding to intact bacteria and penetration of the multi-layered thick cell wall, but not for the degradation of membrane phospholipids that is essential for bacterial killing. Various Gram-positive bacterial species can differ as much as 1000-fold in sPLA(2)-IIA sensitivity despite similar intrinsic enzymatic activity of sPLA(2)-IIA toward the membrane phospholipids of various bacteria. d-alanylation of wall- and lipo-teichoic acids in Staphylococcus aureus and sortase function in Streptococcus pyogenes increase bacterial resistance to sPLA(2)-IIA by up to 100-fold apparently by affecting translocation of bound sPLA(2)-IIA to the cell membrane. Action of the sPLA(2)-IIA and other related sPLA(2) against Gram-negative bacteria is more dependent on cationic properties of the enzyme near the amino-terminus of the protein and collaboration with other host defense proteins that produce alterations of the unique Gram-negative bacterial outer membrane that normally represents a barrier to sPLA(2)-IIA action. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  1. 77 FR 16508 - National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-21

    ...: Group IV Polymers and Resins; Pesticide Active Ingredient Production; and Polyether Polyols Production... pollutants: National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins...: Group IV Polymers and Resins; Pesticide Active Ingredient Production; and Polyether Polyols...

  2. Rickettsial phospholipase A2 as a pathogenic mechanism in a model of cell injury by typhus and spotted fever group rickettsiae.

    PubMed

    Walker, D H; Feng, H M; Popov, V L

    2001-12-01

    Phospholipase A2 activity by typhus group rickettsiae causes hemolysis in vitro. Rickettsial phospholipase A2 has been proposed to mediate entry into the host cell, escape from the phagosome, and cause injury to host cells by both typhus and spotted fever group rickettsiae. In a rickettsial contact-associated cytotoxicity model, the interaction of Rickettsia prowazekii or R. conorii with Vero cells caused temperature-dependent release of 51Cr from the cells. Treatment of rickettsiae, but not the cells, with a phospholipase A2 inhibitor (bromophenacyl bromide) or with antibody to king cobra venom inhibited cell injury. Rickettsial treatment with bromophenacyl bromide inhibited the release of free fatty acids from the host cell. Neither the inhibitor nor antivenom impaired rickettsial active transport of L-lysine. Thus, host cell injury was mediated by a rickettsial phospholipase A2-dependent mechanism.

  3. Enzymatic properties of stingray Dasyatis pastinaca group V, IIA and IB phospholipases A(2): a comparative study.

    PubMed

    Ben Bacha, Abir; Abid, Islem; Horchani, Habib; Mejdoub, Hafedh

    2013-11-01

    In the present study, we have purified the group V phospholipase from the heart of cartilaginous fish stingray Dasyatis pastinaca and compared its biochemical properties with group IIA (sPLA2-IIA) and IB (sPLA2-IB) phospholipases previously purified from pancreas and intestine, respectively. Group V phospholipase (sPLA2-V) was purified to homogeneity by heat treatment, ammonium sulphate precipitation and RP-HPLC. The N-terminal sequence of the purified sPLA2-V exhibits a high degree of homology with those of mammal. The enzyme was found to be monomeric with a molecular mass estimation of 14 kDa. The specific activity of the purified enzyme, measured at pH 8 and 37 °C was 52 U/mg. Like sPLA2-IB and sPLA2-IIA, the sPLA2-V is found to be stable between pH 3 and 11 after 30 min of incubation. The purified sPLA2-V retained 65% of its activity after 10 min of incubation at 70 °C and it absolutely requires Ca(2+) for enzymatic activity. In addition it displayed high tolerance to organic solvents. Kinetic parameters Kmapp, kcat and the deduced catalytic efficiency (kcat/Kmapp) of the purified group-V, -IB and -IIA PLA2s were determined using phosphatidylethanolamine (PE), phosphatidylcholine (PC) or phosphatidylserine (PS) as substrate. The three enzymes hydrolyze the zwiterionic PE and PC substrates more efficiently than anionic PS substrate.

  4. SKELETAL MUSCLE GROUP VIA PHOSPHOLIPASE A2 (iPLA2β): EXPRESSION AND ROLE IN FATTY ACID OXIDATION†

    PubMed Central

    Carper, Michael J.; Zhang, Sheng; Turk, John; Ramanadham, Sasanka

    2009-01-01

    Among the phospholipases A2 (PLA2s) are the Group VI Ca2+-independent PLA2s (iPLA2s) and expression of multiple transcripts of iPLA2 in skeletal muscle has been reported. In the present study, phospholipase activity and sequential ATP and calmodulin affinity column chromatography analyses reveal that skeletal muscle iPLA2 exhibits properties characteristic of the iPLA2β isoform. The phospholipase activity of iPLA2β has been demonstrated to participate in signal transduction, cell proliferation, and apoptosis. We also report here that skeletal muscle from iPLA2β-null mice, relative to wild type muscle, exhibits a reduced capacity to oxidize palmitate but not palmitoyl-CoA or acetyl-CoA in the absence of changes in fatty acid transporters CD36 and CPT1 or β-hydroxyacyl-CoA dehydrogenase activity. Recently, purified iPLA2β was demonstrated to manifest a thioesterase activity which catalyzes hydrolysis of fatty acyl-CoAs. The liberated CoA-SH facilitates fatty acid transport into the mitochondria. In this regard, we find that fractions eluted from the ATP column and containing iPLA2β phospholipase activity also contained acyl-CoA thioesterase activity that was inhibited by the bromoenol lactone (BEL) suicide inhibitor of iPLA2β. We further find that acyl-CoA thioesterase activity in skeletal muscle preparations from iPLA2β-null mice is significantly reduced, relative to WT activity. These findings suggest that the absence of acyl-CoA thioesterase activity of iPLA2β can lead to reduced fatty acyl-CoA generation and impair fatty acid oxidation in iPLA2β-null mice. Our findings therefore reveal a novel function of iPLA2β, related not to its phospholipase activity but to its thioesterase activity, which contributes to optimal fatty acid oxidation in skeletal muscle. PMID:18937505

  5. Band gap scaling laws in group IV nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Chongze; Fu, Xiaonan; Guo, Yangyang; Guo, Zhengxiao; Xia, Congxin; Jia, Yu

    2017-03-01

    By using the first-principles calculations, the band gap properties of nanotubes formed by group IV elements have been investigated systemically. Our results reveal that for armchair nanotubes, the energy gaps at K points in the Brillouin zone decrease as 1/r scaling law with the radii (r) increasing, while they are scaled by ‑1/r 2 + C at Γ points, here, C is a constant. Further studies show that such scaling law of K points is independent of both the chiral vector and the type of elements. Therefore, the band gaps of nanotubes for a given radius can be determined by these scaling laws easily. Interestingly, we also predict the existence of indirect band gap for both germanium and tin nanotubes. Our new findings provide an efficient way to determine the band gaps of group IV element nanotubes by knowing the radii, as well as to facilitate the design of functional nanodevices.

  6. Superconductivity in intercalated group-IV honeycomb structures

    NASA Astrophysics Data System (ADS)

    Flores-Livas, José A.; Sanna, Antonio

    2015-02-01

    We present a theoretical investigation on the electron-phonon superconductivity of honeycomb M X2 layered structures where X is one element of group IV (C, Si, or Ge) and M is an alkali or an alkaline-earth metal. Among the studied compositions we predict a TC of 7 K in RbGe2, 9 K in RbSi2, and 11 K in SrC2. All these compounds feature a strongly anisotropic superconducting gap. Our results show that despite the different doping levels and structural properties, the three families of materials fall into a similar description of their superconducting behavior. This allows us to estimate an upper critical temperature of about 20 K for the class of intercalated group-IV structures, including intercalated graphite and doped graphene.

  7. Large excitonic effects in group-IV sulfide monolayers

    NASA Astrophysics Data System (ADS)

    Tuttle, Blair R.; Alhassan, Saeed M.; Pantelides, Sokrates T.

    2015-12-01

    Large exciton binding energies are a distinguishing feature of two-dimensional semiconductors because of reduced screening, potentially leading to unique optoelectronic applications. Here we use electronic structure methods to calculate the properties of a two-dimensional material class: group-IV monosulfides including SiS, GeS, and SnS. Bulk SiS is predicted to be a metastable layered material. Quasiparticle excitations are calculated with the G0W0 method and the Bethe-Salpeter equation is are used to include electron-hole interactions. For monolayers, strongly bound excitons are found below the quasiparticle absorption edge. The predicted excitonic binding energies are as high as 0.7 eV. Due to large excitonic effects, these group-IV sulfide monolayers have great potential for nanoscale optoelectronic applications.

  8. Band gap scaling laws in group IV nanotubes.

    PubMed

    Wang, Chongze; Fu, Xiaonan; Guo, Yangyang; Guo, Zhengxiao; Xia, Congxin; Jia, Yu

    2017-03-17

    By using the first-principles calculations, the band gap properties of nanotubes formed by group IV elements have been investigated systemically. Our results reveal that for armchair nanotubes, the energy gaps at K points in the Brillouin zone decrease as 1/r scaling law with the radii (r) increasing, while they are scaled by -1/r (2) + C at Γ points, here, C is a constant. Further studies show that such scaling law of K points is independent of both the chiral vector and the type of elements. Therefore, the band gaps of nanotubes for a given radius can be determined by these scaling laws easily. Interestingly, we also predict the existence of indirect band gap for both germanium and tin nanotubes. Our new findings provide an efficient way to determine the band gaps of group IV element nanotubes by knowing the radii, as well as to facilitate the design of functional nanodevices.

  9. Group IV nanotube transistors for next generation ubiquitous computing

    NASA Astrophysics Data System (ADS)

    Fahad, Hossain M.; Hussain, Aftab M.; Sevilla Torres, Galo A.; Banerjee, Sanjay K.; Hussain, Muhammad M.

    2014-06-01

    Evolution in transistor technology from increasingly large power consuming single gate planar devices to energy efficient multiple gate non-planar ultra-narrow (< 20 nm) fins has enhanced the scaling trend to facilitate doubling performance. However, this performance gain happens at the expense of arraying multiple devices (fins) per operation bit, due to their ultra-narrow dimensions (width) originated limited number of charges to induce appreciable amount of drive current. Additionally arraying degrades device off-state leakage and increases short channel characteristics, resulting in reduced chip level energy-efficiency. In this paper, a novel nanotube device (NTFET) topology based on conventional group IV (Si, SiGe) channel materials is discussed. This device utilizes a core/shell dual gate strategy to capitalize on the volume-inversion properties of an ultra-thin (< 10 nm) group IV nanotube channel to minimize leakage and short channel effects while maximizing performance in an area-efficient manner. It is also shown that the NTFET is capable of providing a higher output drive performance per unit chip area than an array of gate-all-around nanowires, while maintaining the leakage and short channel characteristics similar to that of a single gate-all-around nanowire, the latter being the most superior in terms of electrostatic gate control. In the age of big data and the multitude of devices contributing to the internet of things, the NTFET offers a new transistor topology alternative with maximum benefits from performance-energy efficiency-functionality perspective.

  10. Group IVA phospholipase A(2) deficiency prevents CCl4-induced hepatic cell death through the enhancement of autophagy.

    PubMed

    Ishihara, Keiichi; Kanai, Shiho; Tanaka, Kikuko; Kawashita, Eri; Akiba, Satoshi

    2016-02-26

    Group IVA phospholipase A2 (IVA-PLA2), which generates arachidonate, plays a role in inflammation. IVA-PLA2-deficiency reduced hepatotoxicity and hepatocyte cell death in mice that received a single dose of carbon tetrachloride (CCl4) without any inhibitory effects on CCl4-induced lipid peroxidation. An immunoblot analysis of extracts from wild-type mouse- and IVA-PLA2 KO mouse-derived primary hepatocytes that transiently expressed microtubule-associated protein 1 light chain 3B (LC3) revealed a higher amount of LC3-II, a typical index of autophagosome formation, in IVA-PLA2-deficient cells, suggesting the enhancement of constitutive autophagy. IVA-PLA2 may promote CCl4-induced cell death through the suppression of constitutive autophagy in hepatocytes.

  11. Increased activity of group II phospholipase A2 in plasma in rat sodium deoxycholate induced acute pancreatitis

    PubMed Central

    Furue, S; Hori, Y; Kuwabara, K; Ikeuchi, J; Onoyama, H; Yamamoto, M; Tanaka, K

    1997-01-01

    Background—Two different types of secretory phospholipase A2 (PLA2), pancreatic group I (PLA2-I) and non-pancreatic group II (PLA2-II), have been identified and postulated to be associated with the pathogenesis of various diseases, such as acute pancreatitis, septic shock, and multiple organ failure. 
Aims—To investigate the type of secretory PLA2 responsible for its catalytic activity found in plasma and ascites of experimental acute pancreatitis. 
Methods—Acute pancreatitis of differing severity was induced by the injection of different concentrations (1% or 10%) of sodium deoxycholate (DCA) into the common biliopancreatic duct in rats, and catalytic PLA2 activity in plasma and ascites were differentiated by anti-PLA2-I antibody and specific inhibitor of PLA2-II. Survival rate and plasma amylase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were also measured.
Results—In 1% and 10% DCA induced acute pancreatitis, plasma amylase values as well as PLA2 activity in ascites were greatly increased. PLA2 activity in plasma was also notably increased in 10% DCA induced acute pancreatitis, but not in 1% DCA induced acute pancreatitis. PLA2-I specific polyclonal antibody significantly inhibited PLA2 activity in ascites but not that in plasma. In contrast, plasma PLA2 activity was completely suppressed by PLA2-II specific inhibitor. In addition, a high mortality (93% at five hours) and a significant increase in plasma AST and ALT were noted in 10% DCA induced pancreatitis. 
Conclusion—Ascites PLA2 activity is mainly derived from PLA2-I, whereas plasma PLA2 activity is mostly derived from PLA2-II in severe acute pancreatitis, suggesting that increased plasma PLA2-II activity might be implicated in hepatic failure arising after severe acute pancreatitis. 

 Keywords: acute pancreatitis; phospholipase A2; sodium deoxycholate pancreatitis; hepatic failure PMID:9462218

  12. Anti-bactericidal properties of stingray Dasyatis pastinaca groups V, IIA, and IB phospholipases A2: a comparative study.

    PubMed

    Bacha, Abir Ben

    2014-10-01

    Group IIA secreted phospholipase A2 (group IIA sPLA2) is known to display potent Gram-positive bactericidal activity in vitro and in vivo. We have analyzed the bactericidal activity of the full set of native stingray and dromedary groups V, IIA, and IB sPLA2s on several Gram-positive and Gram-negative strains. The rank order potency among both marine and mammal sPLA2s against Gram-positive bacteria is group IIA > V > IB, whereas Gram-negative bacteria exhibited a much higher resistance. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2.The bactericidal efficiency of groups V and IIA sPLA2s was shown to be dependent upon the presence of calcium ions and to a less extent Mg(2+) ions and then a correlation could be made to its hydrolytic activity of membrane phospholipids. Importantly, we showed that stingray and dromedary groups V, IIA, and IB sPLA2s present no cytotoxicity after their incubation with MDA-MB-231cells. stingray groups V and IIA sPLA2s, like mammal ones, may be considered as future therapeutic agents against bacterial infections.

  13. The role of group IIF-secreted phospholipase A2 in epidermal homeostasis and hyperplasia

    PubMed Central

    Yamamoto, Kei; Miki, Yoshimi; Sato, Mariko; Taketomi, Yoshitaka; Nishito, Yasumasa; Taya, Choji; Muramatsu, Kazuaki; Ikeda, Kazutaka; Nakanishi, Hiroki; Taguchi, Ryo; Kambe, Naotomo; Kabashima, Kenji; Lambeau, Gérard; Gelb, Michael H.

    2015-01-01

    Epidermal lipids are important for skin homeostasis. However, the entire picture of the roles of lipids, particularly nonceramide lipid species, in epidermal biology still remains obscure. Here, we report that PLA2G2F, a functionally orphan-secreted phospholipase A2 expressed in the suprabasal epidermis, regulates skin homeostasis and hyperplasic disorders. Pla2g2f−/− mice had a fragile stratum corneum and were strikingly protected from psoriasis, contact dermatitis, and skin cancer. Conversely, Pla2g2f-overexpressing transgenic mice displayed psoriasis-like epidermal hyperplasia. Primary keratinocytes from Pla2g2f−/− mice showed defective differentiation and activation. PLA2G2F was induced by calcium or IL-22 in keratinocytes and preferentially hydrolyzed ethanolamine plasmalogen-bearing docosahexaenoic acid secreted from keratinocytes to give rise to unique bioactive lipids (i.e., protectin D1 and 9S-hydroxyoctadecadienoic acid) that were distinct from canonical arachidonate metabolites (prostaglandins and leukotrienes). Ethanolamine lysoplasmalogen, a PLA2G2F-derived marker product, rescued defective activation of Pla2g2f−/− keratinocytes both in vitro and in vivo. Our results highlight PLA2G2F as a previously unrecognized regulator of skin pathophysiology and point to this enzyme as a novel drug target for epidermal-hyperplasic diseases. PMID:26438362

  14. Group IVA phospholipase A2 regulates testosterone biosynthesis by murine Leydig cells and is required for timely sexual maturation

    PubMed Central

    Kurusu, Shiro; Sapirstein, Adam; Sawada, Harumi; Kawaminami, Mitsumori; Bonventre, Joseph V.

    2015-01-01

    In the present paper, we report that PLA2G4A (Group IVA phospholipase A2) is important in the development and function of rodent testes. Interstitial cells of rat testes had high PLA2 (phospholipase A2) activity that was very sensitive to the PLA2G4A-preferential inhibitor AACOCF3 (arachidonyl trifluoromethyl ketone). PLA2G4A protein was expressed primarily in the interstitial cells of wild-type mouse testes throughout maturation. Although Pla2g4a knockout (Pla2g4a−/− ) male mice are fertile, their sexual maturation was delayed, as indicated by cauda epididymal sperm count and seminal vesicle development. Delayed function of Pla2g4a−/− mice testes was associated with histological abnormalities including disorganized architecture, swollen appearance and fewer interstitial cells. Basal secretion of testosterone was attenuated significantly and steroidogenic response to hCG (human chorionic gonadotropin) treatment was reduced in Pla2g4a−/− mice compared with their Pla2g4a+/+ littermates during the sexual maturation period. Chemical inhibition of PLA2G4A activity by AACOCF3 or pyrrophenone significantly reduced hCG-stimulated testosterone production in cultured rat interstitial cells. AACOCF3 inhibited forskolin- and cAMP analogue-stimulated testosterone production. These results provide the first evidence that PLA2G4A plays a role in male testes physiology and development. These results may have implications for the potential clinical use of PLA2G4A inhibitors. PMID:21762109

  15. Group X Secreted Phospholipase A2 Releases ω3 Polyunsaturated Fatty Acids, Suppresses Colitis, and Promotes Sperm Fertility*

    PubMed Central

    Murase, Remi; Sato, Hiroyasu; Yamamoto, Kei; Ushida, Ayako; Nishito, Yasumasa; Ikeda, Kazutaka; Kobayashi, Tetsuyuki; Yamamoto, Toshinori; Taketomi, Yoshitaka; Murakami, Makoto

    2016-01-01

    Within the secreted phospholipase A2 (sPLA2) family, group X sPLA2 (sPLA2-X) has the highest capacity to hydrolyze cellular membranes and has long been thought to promote inflammation by releasing arachidonic acid, a precursor of pro-inflammatory eicosanoids. Unexpectedly, we found that transgenic mice globally overexpressing human sPLA2-X (PLA2G10-Tg) displayed striking immunosuppressive and lean phenotypes with lymphopenia and increased M2-like macrophages, accompanied by marked elevation of free ω3 polyunsaturated fatty acids (PUFAs) and their metabolites. Studies using Pla2g10-deficient mice revealed that endogenous sPLA2-X, which is highly expressed in the colon epithelium and spermatozoa, mobilized ω3 PUFAs or their metabolites to protect against dextran sulfate-induced colitis and to promote fertilization, respectively. In colitis, sPLA2-X deficiency increased colorectal expression of Th17 cytokines, and ω3 PUFAs attenuated their production by lamina propria cells partly through the fatty acid receptor GPR120. In comparison, cytosolic phospholipase A2 (cPLA2α) protects from colitis by mobilizing ω6 arachidonic acid metabolites, including prostaglandin E2. Thus, our results underscore a previously unrecognized role of sPLA2-X as an ω3 PUFA mobilizer in vivo, segregated mobilization of ω3 and ω6 PUFA metabolites by sPLA2-X and cPLA2α, respectively, in protection against colitis, and the novel role of a particular sPLA2-X-driven PUFA in fertilization. PMID:26828067

  16. Group X Secreted Phospholipase A2 Releases ω3 Polyunsaturated Fatty Acids, Suppresses Colitis, and Promotes Sperm Fertility.

    PubMed

    Murase, Remi; Sato, Hiroyasu; Yamamoto, Kei; Ushida, Ayako; Nishito, Yasumasa; Ikeda, Kazutaka; Kobayashi, Tetsuyuki; Yamamoto, Toshinori; Taketomi, Yoshitaka; Murakami, Makoto

    2016-03-25

    Within the secreted phospholipase A2(sPLA2) family, group X sPLA2(sPLA2-X) has the highest capacity to hydrolyze cellular membranes and has long been thought to promote inflammation by releasing arachidonic acid, a precursor of pro-inflammatory eicosanoids. Unexpectedly, we found that transgenic mice globally overexpressing human sPLA2-X (PLA2G10-Tg) displayed striking immunosuppressive and lean phenotypes with lymphopenia and increased M2-like macrophages, accompanied by marked elevation of free ω3 polyunsaturated fatty acids (PUFAs) and their metabolites. Studies usingPla2g10-deficient mice revealed that endogenous sPLA2-X, which is highly expressed in the colon epithelium and spermatozoa, mobilized ω3 PUFAs or their metabolites to protect against dextran sulfate-induced colitis and to promote fertilization, respectively. In colitis, sPLA2-X deficiency increased colorectal expression of Th17 cytokines, and ω3 PUFAs attenuated their production by lamina propria cells partly through the fatty acid receptor GPR120. In comparison, cytosolic phospholipase A2(cPLA2α) protects from colitis by mobilizing ω6 arachidonic acid metabolites, including prostaglandin E2 Thus, our results underscore a previously unrecognized role of sPLA2-X as an ω3 PUFA mobilizerin vivo, segregated mobilization of ω3 and ω6 PUFA metabolites by sPLA2-X and cPLA2α, respectively, in protection against colitis, and the novel role of a particular sPLA2-X-driven PUFA in fertilization.

  17. Nanomembrane-based materials for Group IV semiconductor quantum electronics.

    PubMed

    Paskiewicz, D M; Savage, D E; Holt, M V; Evans, P G; Lagally, M G

    2014-02-27

    Strained-silicon/relaxed-silicon-germanium alloy (strained-Si/SiGe) heterostructures are the foundation of Group IV-element quantum electronics and quantum computation, but current materials quality limits the reliability and thus the achievable performance of devices. In comparison to conventional approaches, single-crystal SiGe nanomembranes are a promising alternative as substrates for the epitaxial growth of these heterostructures. Because the nanomembrane is truly a single crystal, in contrast to the conventional SiGe substrate made by compositionally grading SiGe grown on bulk Si, significant improvements in quantum electronic-device reliability may be expected with nanomembrane substrates. We compare lateral strain inhomogeneities and the local mosaic structure (crystalline tilt) in strained-Si/SiGe heterostructures that we grow on SiGe nanomembranes and on compositionally graded SiGe substrates, with micro-Raman mapping and nanodiffraction, respectively. Significant structural improvements are found using SiGe nanomembranes.

  18. 77 FR 1267 - National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-09

    ... Group IV Polymers and Resins MACT standards, the typical control devices used to reduce organic HAP... Hazardous Air Pollutant Emissions: Group IV Polymers and Resins; Pesticide Active Ingredient Production; and... Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins; Pesticide...

  19. Phosphatidylcholine-specific phospholipase C and sphingomyelinase activities in bacteria of the Bacillus cereus group.

    PubMed

    Pomerantsev, A P; Kalnin, K V; Osorio, M; Leppla, S H

    2003-11-01

    Bacillus anthracis is nonhemolytic, even though it is closely related to the highly hemolytic Bacillus cereus. Hemolysis by B. cereus results largely from the action of phosphatidylcholine-specific phospholipase C (PC-PLC) and sphingomyelinase (SPH), encoded by the plc and sph genes, respectively. In B. cereus, these genes are organized in an operon regulated by the global regulator PlcR. B. anthracis contains a highly similar cereolysin operon, but it is transcriptionally silent because the B. anthracis PlcR is truncated at the C terminus. Here we report the cloning, expression, purification, and enzymatic characterization of PC-PLC and SPH from B. cereus and B. anthracis. We also investigated the effects of expressing PlcR on the expression of plc and sph. In B. cereus, PlcR was found to be a positive regulator of plc but a negative regulator of sph. Replacement of the B. cereus plcR gene by its truncated orthologue from B. anthracis eliminated the activities of both PC-PLC and SPH, whereas introduction into B. anthracis of the B. cereus plcR gene with its own promoter did not activate cereolysin expression. Hemolytic activity was detected in B. anthracis strains containing the B. cereus plcR gene on a multicopy plasmid under control of the strong B. anthracis protective antigen gene promoter or in a strain carrying a multicopy plasmid containing the entire B. cereus plc-sph operon. Slight hemolysis and PC-PLC activation were found when PlcR-producing B. anthracis strains were grown under anaerobic-plus-CO(2) or especially under aerobic-plus-CO(2) conditions. Unmodified parental B. anthracis strains did not demonstrate obvious hemolysis under the same conditions.

  20. Activation of group IVC phospholipase A2 by polycyclic aromatic hydrocarbons induces apoptosis of human coronary artery endothelial cells

    PubMed Central

    Richards, Sean M.; Elgayyar, Mona A.; Menn, Fu-Minn; Vulava, Vijay M.; McKay, Larry; Sanseverino, John; Sayler, Gary; Tucker, Dawn E.; Leslie, Christina C.; Lu, Kim P.; Ramos, Kenneth S.

    2016-01-01

    Exposure to environmental pollutants, such as polycyclic aromatic hydrocarbons (PAHs) found in coal tar mixtures and tobacco sources, is considered a significant risk factor for the development of heart disease in humans. The goal of this study was to determine the influence of PAHs present at a Superfund site on human coronary artery endothelial cell (HCAEC) phospholipase A2 (PLA2) activity and apoptosis. Extremely high levels of 12 out of 15 EPA high-priority PAHs were present in both the streambed and floodplain sediments at a site where an urban creek and its adjacent floodplain were extensively contaminated by PAHs and other coal tar compounds. Nine of the 12 compounds and a coal tar mixture (SRM 1597A) activated group IVC PLA2 in HCAECs, and activation of this enzyme was associated with histone fragmentation and poly (ADP) ribose polymerase (PARP) cleavage. Genetic silencing of group IVC PLA2 inhibited both 3H-fatty acid release and histone fragmentation by PAHs and SRM 1597A, indicating that individual PAHs and a coal tar mixture induce apoptosis of HCAECs via a mechanism that involves group IVC PLA2. Western blot analysis of aortas isolated from feral mice (Peromyscus leucopus) inhabiting the Superfund site showed increased PARP and caspase-3 cleavage when compared to reference mice. These data suggest that PAHs induce apoptosis of HCAECs via activation of group IVC PLA2. PMID:21132278

  1. Phospholipases A in Trypanosomatids

    PubMed Central

    Belaunzarán, María Laura; Lammel, Estela María; de Isola, Elvira Luisa Durante

    2011-01-01

    Phospholipases are a complex and important group of enzymes widespread in nature, that play crucial roles in diverse biochemical processes and are classified as A1, A2, C, and D. Phospholipases A1 and A2 activities have been linked to pathogenesis in various microorganisms, and particularly in pathogenic protozoa they have been implicated in cell invasion. Kinetoplastids are a group of flagellated protozoa, including extra- and intracellular parasites that cause severe disease in humans and animals. In the present paper, we will mainly focus on the three most important kinetoplastid human pathogens, Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp., giving a perspective of the research done up to now regarding biochemical, biological, and molecular characteristics of Phospholipases A1 and A2 and their contribution to pathogenesis. PMID:21603263

  2. Two-dimensional multiferroics in monolayer group IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Wang, Hua; Qian, Xiaofeng

    2017-03-01

    Low-dimensional multiferroic materials hold great promises in miniaturized device applications such as nanoscale transducers, actuators, sensors, photovoltaics, and nonvolatile memories. Here, using first-principles theory we predict that two-dimensional (2D) monolayer group IV monochalcogenides including GeS, GeSe, SnS, and SnSe are a class of 2D semiconducting multiferroics with giant strongly-coupled in-plane spontaneous ferroelectric polarization and spontaneous ferroelastic lattice strain that are thermodynamically stable at room temperature and beyond, and can be effectively modulated by elastic strain engineering. Their optical absorption spectra exhibit strong in-plane anisotropy with visible-spectrum excitonic gaps and sizable exciton binding energies, rendering the unique characteristics of low-dimensional semiconductors. More importantly, the predicted low domain wall energy and small migration barrier together with the coupled multiferroic order and anisotropic electronic structures suggest their great potentials for tunable multiferroic functional devices by manipulating external electrical, mechanical, and optical field to control the internal responses, and enable the development of four device concepts including 2D ferroelectric memory, 2D ferroelastic memory, and 2D ferroelastoelectric nonvolatile photonic memory as well as 2D ferroelectric excitonic photovoltaics.

  3. Physiological Roles of Group X-secreted Phospholipase A2 in Reproduction, Gastrointestinal Phospholipid Digestion, and Neuronal Function*

    PubMed Central

    Sato, Hiroyasu; Isogai, Yuki; Masuda, Seiko; Taketomi, Yoshitaka; Miki, Yoshimi; Kamei, Daisuke; Hara, Shuntaro; Kobayashi, Tetsuyuki; Ishikawa, Yukio; Ishii, Toshiharu; Ikeda, Kazutaka; Taguchi, Ryo; Ishimoto, Yoshikazu; Suzuki, Noriko; Yokota, Yasunori; Hanasaki, Kohji; Suzuki-Yamamoto, Toshiko; Yamamoto, Kei; Murakami, Makoto

    2011-01-01

    Although the secreted phospholipase A2 (sPLA2) family has been generally thought to participate in pathologic events such as inflammation and atherosclerosis, relatively high and constitutive expression of group X sPLA2 (sPLA2-X) in restricted sites such as reproductive organs, the gastrointestinal tract, and peripheral neurons raises a question as to the roles played by this enzyme in the physiology of reproduction, digestion, and the nervous system. Herein we used mice with gene disruption or transgenic overexpression of sPLA2-X to clarify the homeostatic functions of this enzyme at these locations. Our results suggest that sPLA2-X regulates 1) the fertility of spermatozoa, not oocytes, beyond the step of flagellar motility, 2) gastrointestinal phospholipid digestion, perturbation of which is eventually linked to delayed onset of a lean phenotype with reduced adiposity, decreased plasma leptin, and improved muscle insulin tolerance, and 3) neuritogenesis of dorsal root ganglia and the duration of peripheral pain nociception. Thus, besides its inflammatory action proposed previously, sPLA2-X participates in physiologic processes including male fertility, gastrointestinal phospholipid digestion linked to adiposity, and neuronal outgrowth and sensing. PMID:21266581

  4. Physiological roles of group X-secreted phospholipase A2 in reproduction, gastrointestinal phospholipid digestion, and neuronal function.

    PubMed

    Sato, Hiroyasu; Isogai, Yuki; Masuda, Seiko; Taketomi, Yoshitaka; Miki, Yoshimi; Kamei, Daisuke; Hara, Shuntaro; Kobayashi, Tetsuyuki; Ishikawa, Yukio; Ishii, Toshiharu; Ikeda, Kazutaka; Taguchi, Ryo; Ishimoto, Yoshikazu; Suzuki, Noriko; Yokota, Yasunori; Hanasaki, Kohji; Suzuki-Yamamoto, Toshiko; Yamamoto, Kei; Murakami, Makoto

    2011-04-01

    Although the secreted phospholipase A(2) (sPLA(2)) family has been generally thought to participate in pathologic events such as inflammation and atherosclerosis, relatively high and constitutive expression of group X sPLA(2) (sPLA(2)-X) in restricted sites such as reproductive organs, the gastrointestinal tract, and peripheral neurons raises a question as to the roles played by this enzyme in the physiology of reproduction, digestion, and the nervous system. Herein we used mice with gene disruption or transgenic overexpression of sPLA(2)-X to clarify the homeostatic functions of this enzyme at these locations. Our results suggest that sPLA(2)-X regulates 1) the fertility of spermatozoa, not oocytes, beyond the step of flagellar motility, 2) gastrointestinal phospholipid digestion, perturbation of which is eventually linked to delayed onset of a lean phenotype with reduced adiposity, decreased plasma leptin, and improved muscle insulin tolerance, and 3) neuritogenesis of dorsal root ganglia and the duration of peripheral pain nociception. Thus, besides its inflammatory action proposed previously, sPLA(2)-X participates in physiologic processes including male fertility, gastrointestinal phospholipid digestion linked to adiposity, and neuronal outgrowth and sensing.

  5. Interaction of low molecular weight group IIA phospholipase A2 with apoptotic human T cells: role of heparan sulfate proteoglycans.

    PubMed

    Boilard, Eric; Bourgoin, Sylvain G; Bernatchez, Chantale; Poubelle, Patrice E; Surette, Marc E

    2003-06-01

    Human group IIA phospholipase A2 (hIIA PLA2) is a 14 kDa secreted enzyme associated with inflammatory diseases. A newly discovered property of hIIA PLA2 is the binding affinity for the heparan sulfate proteoglycan (HSPG) glypican-1. In this study, the binding of hIIA PLA2 to apoptotic human T cells was investigated. Little or no exogenous hIIA PLA2 bound to CD3-activated T cells but significant binding was measured on activated T cells induced to undergo apoptosis by anti-CD95. Binding to early apoptotic T cells was greater than to late apoptotic cells. The addition of heparin and the hydrolysis of HSPG by heparinase III only partially inhibited hIIA PLA2 binding to apoptotic cells, suggesting an interaction with both HSPG and other binding protein(s). Two low molecular weight HSPG were coimmunoprecipitated with hIIA PLA2 from apoptotic T cells, but not from living cells. Treatment of CD95-stimulated T cells with hIIA PLA2 resulted in the release of arachidonic acid but not oleic acid from cells and this release was blocked by heparin and heparinase III. Altogether, these results suggest a role for hIIA PLA2 in the release of arachidonic acid from apoptotic cells through interactions with HSPG and its potential implication in the progression of inflammatory diseases.

  6. Group X Secretory Phospholipase A2 Negatively Regulates ABCA1 and ABCG1 expression and cholesterol efflux in macrophages

    PubMed Central

    Shridas, Preetha; Bailey, William M; Gizard, Florence; Oslund, Rob C; Gelb, Michael H; Bruemmer, Dennis; Webb, Nancy R

    2010-01-01

    Objectives Group X secretory phospholipase A2 (GX sPLA2) potently hydrolyzes plasma membranes to generate lysophospholipids and free fatty acids and has been implicated in inflammatory diseases including atherosclerosis. Here we identify a novel role for GX sPLA2 in modulating ABCA1 and ABCG1 expression and hence macrophage cholesterol efflux. Methods and Results Overexpression or exogenous addition of GX sPLA2 significantly reduced ABCA1 and ABCG1 expression in J774 macrophage-like cells, whereas GX sPLA2 deficiency in mouse peritoneal macrophages (MPMs) was associated with enhanced expression. Altered ABC transporter expression led to reduced cholesterol efflux in GX sPLA2 overexpressing J774 cells, and increased efflux in GX sPLA2-deficient MPMs. Gene regulation was dependent on GX sPLA2 catalytic activity, mimicked by arachidonic acid, abrogated when LXRα/β expression was suppressed, and partially reversed by the LXR agonist T0901317. Reporter assays indicated that GX sPLA2 suppresses the ability of LXR to trans-activate its promoters through a mechanism involving the C-terminal portion of LXR spanning the ligand binding domain. Conclusions GX sPLA2 modulates gene expression in macrophages by generating lipolytic products that suppress LXR activation. GX sPLA2 may play a previously unrecognized role in atherosclerotic lipid accumulation by negatively regulating genes critical for cellular cholesterol efflux. PMID:20844270

  7. The Finding of a Group IIE Phospholipase A2 Gene in a Specified Segment of Protobothrops flavoviridis Genome and Its Possible Evolutionary Relationship to Group IIA Phospholipase A2 Genes

    PubMed Central

    Yamaguchi, Kazuaki; Chijiwa, Takahito; Ikeda, Naoki; Shibata, Hiroki; Fukumaki, Yasuyuki; Oda-Ueda, Naoko; Hattori, Shosaku; Ohno, Motonori

    2014-01-01

    The genes encoding group IIE phospholipase A2, abbreviated as IIE PLA2, and its 5' and 3' flanking regions of Crotalinae snakes such as Protobothrops flavoviridis, P. tokarensis, P. elegans, and Ovophis okinavensis, were found and sequenced. The genes consisted of four exons and three introns and coded for 22 or 24 amino acid residues of the signal peptides and 134 amino acid residues of the mature proteins. These IIE PLA2s show high similarity to those from mammals and Colubridae snakes. The high expression level of IIE PLA2s in Crotalinae venom glands suggests that they should work as venomous proteins. The blast analysis indicated that the gene encoding OTUD3, which is ovarian tumor domain-containing protein 3, is located in the 3' downstream of IIE PLA2 gene. Moreover, a group IIA PLA2 gene was found in the 5' upstream of IIE PLA2 gene linked to the OTUD3 gene (OTUD3) in the P. flavoviridis genome. It became evident that the specified arrangement of IIA PLA2 gene, IIE PLA2 gene, and OTUD3 in this order is common in the genomes of humans to snakes. The present finding that the genes encoding various secretory PLA2s form a cluster in the genomes of humans to birds is closely related to the previous finding that six venom PLA2 isozyme genes are densely clustered in the so-called NIS-1 fragment of the P. flavoviridis genome. It is also suggested that venom IIA PLA2 genes may be evolutionarily derived from the IIE PLA2 gene. PMID:25529307

  8. Group X Phospholipase A2 Stimulates the Proliferation of Colon Cancer Cells by Producing Various Lipid Mediators

    PubMed Central

    Surrel, Fanny; Jemel, Ikram; Boilard, Eric; Bollinger, James G.; Payré, Christine; Mounier, Carine M.; Talvinen, Kati A.; Laine, Veli J. O.; Nevalainen, Timo J.; Gelb, Michael H.

    2009-01-01

    Among mammalian secreted phospholipases A2 (sPLA2s), the group X enzyme has the most potent hydrolyzing capacity toward phosphatidylcholine, the major phospholipid of cell membrane and lipoproteins. This enzyme has recently been implicated in chronic inflammatory diseases such as atherosclerosis and asthma and may also play a role in colon tumorigenesis. We show here that group X sPLA2 [mouse (m)GX] is one of the most highly expressed PLA2 in the mouse colon and that recombinant mouse and human enzymes stimulate proliferation and mitogen-activated protein kinase activation of various colon cell lines, including Colon-26 cancer cells. Among various recombinant sPLA2s, mGX is the most potent enzyme to stimulate cell proliferation. Based on the use of sPLA2 inhibitors, catalytic site mutants, and small interfering RNA silencing of cytosolic PLA2α and M-type sPLA2 receptor, we demonstrate that mGX promotes cell proliferation independently of the receptor and via its intrinsic catalytic activity and production of free arachidonic acid and lysophospholipids, which are mitogenic by themselves. mGX can also elicit the production of large amounts of prostaglandin E2 and other eicosanoids from Colon-26 cells, but these lipid mediators do not play a role in mGX-induced cell proliferation because inhibitors of cyclooxygenases and lipoxygenases do not prevent sPLA2 mitogenic effects. Together, our results indicate that group X sPLA2 may play an important role in colon tumorigenesis by promoting cancer cell proliferation and releasing various lipid mediators involved in other key events in cancer progression. PMID:19602573

  9. Group X phospholipase A2 stimulates the proliferation of colon cancer cells by producing various lipid mediators.

    PubMed

    Surrel, Fanny; Jemel, Ikram; Boilard, Eric; Bollinger, James G; Payré, Christine; Mounier, Carine M; Talvinen, Kati A; Laine, Veli J O; Nevalainen, Timo J; Gelb, Michael H; Lambeau, Gérard

    2009-10-01

    Among mammalian secreted phospholipases A2 (sPLA(2)s), the group X enzyme has the most potent hydrolyzing capacity toward phosphatidylcholine, the major phospholipid of cell membrane and lipoproteins. This enzyme has recently been implicated in chronic inflammatory diseases such as atherosclerosis and asthma and may also play a role in colon tumorigenesis. We show here that group X sPLA(2) [mouse (m)GX] is one of the most highly expressed PLA(2) in the mouse colon and that recombinant mouse and human enzymes stimulate proliferation and mitogen-activated protein kinase activation of various colon cell lines, including Colon-26 cancer cells. Among various recombinant sPLA(2)s, mGX is the most potent enzyme to stimulate cell proliferation. Based on the use of sPLA(2) inhibitors, catalytic site mutants, and small interfering RNA silencing of cytosolic PLA(2)alpha and M-type sPLA(2) receptor, we demonstrate that mGX promotes cell proliferation independently of the receptor and via its intrinsic catalytic activity and production of free arachidonic acid and lysophospholipids, which are mitogenic by themselves. mGX can also elicit the production of large amounts of prostaglandin E2 and other eicosanoids from Colon-26 cells, but these lipid mediators do not play a role in mGX-induced cell proliferation because inhibitors of cyclooxygenases and lipoxygenases do not prevent sPLA(2) mitogenic effects. Together, our results indicate that group X sPLA(2) may play an important role in colon tumorigenesis by promoting cancer cell proliferation and releasing various lipid mediators involved in other key events in cancer progression.

  10. Alleviation of high-fat diet-induced fatty liver damage in group IVA phospholipase A2-knockout mice.

    PubMed

    Ii, Hiromi; Yokoyama, Naoki; Yoshida, Shintaro; Tsutsumi, Kae; Hatakeyama, Shinji; Sato, Takashi; Ishihara, Keiichi; Akiba, Satoshi

    2009-12-01

    Hepatic fat deposition with hepatocellular damage, a feature of non-alcoholic fatty liver disease, is mediated by several putative factors including prostaglandins. In the present study, we examined whether group IVA phospholipase A(2) (IVA-PLA(2)), which catalyzes the first step in prostanoid biosynthesis, is involved in the development of fatty liver, using IVA-PLA(2)-knockout mice. Male wild-type mice on high-fat diets (20% fat and 1.25% cholesterol) developed hepatocellular vacuolation and liver hypertrophy with an increase in the serum levels of liver damage marker aminotransferases when compared with wild-type mice fed normal diets. These high-fat diet-induced alterations were markedly decreased in IVA-PLA(2)-knockout mice. Hepatic triacylglycerol content was lower in IVA-PLA(2)-knockout mice than in wild-type mice under normal dietary conditions. Although high-fat diets increased hepatic triacylglycerol content in both genotypes, the degree was lower in IVA-PLA(2)-knockout mice than in wild-type mice. Under the high-fat dietary conditions, IVA-PLA(2)-knockout mice had lower epididymal fat pad weight and smaller adipocytes than wild-type mice. The serum level of prostaglandin E(2), which has a fat storage effect, was lower in IVA-PLA(2)-knockout mice than in wild-type mice, irrespective of the kind of diet. In both genotypes, high-fat diets increased serum leptin levels equally between the two groups, but did not affect the serum levels of adiponectin, resistin, free fatty acid, triacylglycerol, glucose, or insulin. Our findings suggest that a deficiency of IVA-PLA(2) alleviates fatty liver damage caused by high-fat diets, probably because of the lower generation of IVA-PLA(2) metabolites, such as prostaglandin E(2). IVA-PLA(2) could be a promising therapeutic target for obesity-related diseases including non-alcoholic fatty liver disease.

  11. Group V Secretory Phospholipase A2 Is Involved in Tubular Integrity and Sodium Handling in the Kidney

    PubMed Central

    Moraes-Santos, Felipe; Landgraf, Sharon Schilling; Silva, Leandro Souza; Sirtoli, Gabriela Modenesi; Zamith-Miranda, Daniel; Takiya, Christina Maeda; Pinheiro, Ana Acacia Sá; Diaz, Bruno Lourenço; Caruso-Neves, Celso

    2016-01-01

    Group V (GV) phospholipase A2 (PLA2) is a member of the family of secreted PLA2 (sPLA2) enzymes. This enzyme has been identified in several organs, including the kidney. However, the physiologic role of GV sPLA2 in the maintenance of renal function remains unclear. We used mice lacking the gene encoding GV sPLA2 (Pla2g5−/−) and wild-type breeding pairs in the experiments. Mice were individually housed in metabolic cages and 48-h urine was collected for biochemical assays. Kidney samples were evaluated for glomerular morphology, renal fibrosis, and expression/activity of the (Na+ + K+)-ATPase α1 subunit. We observed that plasma creatinine levels were increased in Pla2g5−/− mice following by a decrease in creatinine clearance. The levels of urinary protein were higher in Pla2g5−/− mice than in the control group. Markers of tubular integrity and function such as γ-glutamyl transpeptidase, lactate dehydrogenase, and sodium excretion fraction (FENa+) were also increased in Pla2g5−/− mice. The increased FENa+ observed in Pla2g5−/− mice was correlated to alterations in cortical (Na+ + K+) ATPase activity/ expression. In addition, the kidney from Pla2g5−/− mice showed accumulation of matrix in corticomedullary glomeruli and tubulointerstitial fibrosis. These data suggest GV sPLA2 is involved in the maintenance of tubular cell function and integrity, promoting sodium retention through increased cortical (Na+ + K+)-ATPase expression and activity. PMID:26820468

  12. Characterisation and expression of secretory phospholipase A2 group IB during ontogeny of Atlantic cod ( Gadus morhua).

    PubMed

    Sæle, Øystein; Nordgreen, Andreas; Olsvik, Pål A; Hamre, Kristin

    2011-01-01

    The pancreatic enzyme secretory phospholipase A2 group IB (sPLA2 IB) hydrolyses phospholipids at the sn-2 position, resulting in a NEFA and a lyso-phospholipid, which are then absorbed by the enterocytes. The sPLA2 IB is a member of a family of nineteen enzymes sharing the same catalytic ability, of which nine are cytosolic and ten are secretory. Presently, there are no pharmacological tools to separate between the different secretory enzymes when measuring the enzymatic activity. Thus, it is important to support activity data with more precise techniques when isolation of intestinal content is not possible for analysis, as in the case of small teleost larvae, where the whole animal is sometimes analysed. In the present study, we characterise the sPLA2 IB gene in Atlantic cod (Gadus morhua) and describe its ontogeny at the genetic and protein level and compare this to the total sPLA2 activity level. A positive correlation was found between the expression of sPLA2 IB mRNA and protein. Both remained stable and low during the larval stage followed by an increase from day 62 posthatch, coinciding with the development of the pyloric ceaca. Meanwhile, total sPLA2 enzyme activity in cod was stable and relatively high during the early stages when larvae were fed live prey, followed by a decrease in activity when the fish were weaned to a formulated diet. Thus, the expression of sPLA2 IB mRNA and protein did not correlate with total sPLA2 activity.

  13. Interleukin-22-Induced Antimicrobial Phospholipase A2 Group IIA Mediates Protective Innate Immunity of Nonhematopoietic Cells against Listeria monocytogenes.

    PubMed

    Okita, Yamato; Shiono, Takeru; Yahagi, Ayano; Hamada, Satoru; Umemura, Masayuki; Matsuzaki, Goro

    2015-12-07

    Listeria monocytogenes is a bacterial pathogen which establishes intracellular parasitism in various cells, including macrophages and nonhematopoietic cells, such as hepatocytes. It has been reported that several proinflammatory cytokines have pivotal roles in innate protection against L. monocytogenes infection. We found that a proinflammatory cytokine, interleukin 22 (IL-22), was expressed by CD3(+) CD4(+) T cells at an early stage of L. monocytogenes infection in mice. To assess the influence of IL-22 on L. monocytogenes infection in hepatocytes, cells of a human hepatocellular carcinoma line, HepG2, were treated with IL-22 before L. monocytogenes infection in vitro. Gene expression analysis of the IL-22-treated HepG2 cells identified phospholipase A2 group IIA (PLA2G2A) as an upregulated antimicrobial molecule. Addition of recombinant PLA2G2A to the HepG2 culture significantly suppressed L. monocytogenes infection. Culture supernatant of the IL-22-treated HepG2 cells contained bactericidal activity against L. monocytogenes, and the activity was abrogated by a specific PLA2G2A inhibitor, demonstrating that HepG2 cells secreted PLA2G2A, which killed extracellular L. monocytogenes. Furthermore, colocalization of PLA2G2A and L. monocytogenes was detected in the IL-22-treated infected HepG2 cells, which suggests involvement of PLA2G2A in the mechanism of intracellular killing of L. monocytogenes by HepG2 cells. These results suggest that IL-22 induced at an early stage of L. monocytogenes infection enhances innate immunity against L. monocytogenes in the liver by stimulating hepatocytes to produce an antimicrobial molecule, PLA2G2A.

  14. Group IVA phospholipase A2-associated production of MMP-9 in macrophages and formation of atherosclerotic lesions.

    PubMed

    Ii, Hiromi; Hontani, Naoya; Toshida, Issei; Oka, Mayuko; Sato, Takashi; Akiba, Satoshi

    2008-03-01

    Matrix metalloproteinase-9 (MMP-9) is involved in atherogenesis, and the production of MMP-9 in macrophages is considered to be mediated by the arachidonic acid cascade. The present study examined the possible involvement of group IVA phospholipase A2 (IVA-PLA2), a key enzyme in the arachidonic acid cascade, in the production of MMP-9 induced by oxidized low-density lipoprotein (oxLDL) in macrophages and high-fat diet-induced formation of atherosclerotic lesions using IVA-PLA2-deficient mice (C57BL/6 background). In wild-type mouse peritoneal macrophages, oxLDL induced an increase in MMP-9 in the culture medium. The oxLDL-promoted production of MMP-9 was markedly reduced in IVA-PLA2-deficient macrophages compared to wild-type macrophages. Feeding of wild-type mice with a high-fat diet caused the formation of early atherosclerotic lesions in the aortic root with increases in MMP-9 and macrophages in the lesions and with higher serum levels of total cholesterol. Such lesions were apparently less severe in IVA-PLA2-deficient mice fed a high-fat diet, despite higher total cholesterol levels. Under the conditions, a high-fat diet reduced the serum levels of high-density lipoprotein-cholesterol (HDL-C) in wild-type mice. However, IVA-PLA2-deficient mice fed a high-fat diet were protected against the decrease in HDL-C levels. The present results suggest that IVA-PLA2 is involved in the oxLDL-induced production of MMP-9 in macrophages and the high-fat diet-induced formation of early atherosclerotic lesions. The protection against the lesions in IVA-PLA2-deficient mice may be ascribable, in part, to the impaired production of MMP-9 and/or the maintained levels of HDL-C.

  15. Expression of group IIA phospholipase A2 is an independent predictor of favorable outcome for patients with gastric cancer.

    PubMed

    Wang, Xi; Huang, Chun-Jin; Yu, Guan-Zhen; Wang, Jie-Jun; Wang, Rui; Li, Yu-Mei; Wu, Qiong

    2013-10-01

    Growing evidence suggests that phospholipase A2 (PLA2) plays a pivotal role in tumorigenesis in human gastrointestinal cancer. One of the well-studied isoforms of PLA2, group IIA PLA2 (PLA2G2A), appears to exert its protumorigenic or antitumorigenic effects in a tissue-specific manner. The present study was designed to determine the expression profile and prognostic value of PLA2G2A in gastric cancer in a large Chinese cohort. By using real-time polymerase chain reaction, the amount of PLA2G2A messenger RNA in 60 pairs of fresh gastric tumors and adjacent noncancerous mucosa was measured. The immunostaining of PLA2G2A in 866 gastric cancers with paired noncancerous tissues was assayed. No expression of PLA2G2A was found in normal gastric mucosa, and focal expression of PLA2G2A was noticed in intestinal metaplasia, whereas significantly increased expression of PLA2G2A was observed in the cytoplasm of gastric cancer cells. Furthermore, the extent of PLA2G2A expression was associated with tumor size (P < .001), tumor differentiation (P = .001), T class (P < .001), N class (P < .001), and TNM stage (P < .001) of gastric cancer. Multivariate analysis showed that PLA2G2A expression was an independent predictor of survival for patients with gastric cancer (P = .024). Expression of PLA2G2A seems to be protective for patients with gastric cancer (hazard ratio, 1.423; 95% confidence interval, 1.047-1.935), and it may be a target for achieving better treatment outcomes.

  16. Crystal structures of human group-VIIA phospholipase A2 inhibited by organophosphorus nerve agents exhibit non-aged complexes

    SciTech Connect

    Samanta, Uttamkumar; Kirby, Stephen D.; Srinivasan, Prabhavathi; Cerasoli, Douglas M.; Bahnson, Brian J.

    2009-09-02

    The enzyme group-VIIA phospholipase A2 (gVIIA-PLA2) is bound to lipoproteins in human blood and hydrolyzes the ester bond at the sn-2 position of phospholipid substrates with a short sn-2 chain. The enzyme belongs to a serine hydrolase superfamily of enzymes, which react with organophosphorus (OP) nerve agents. OPs ultimately exert their toxicity by inhibiting human acetycholinesterase at nerve synapses, but may additionally have detrimental effects through inhibition of other serine hydrolases. We have solved the crystal structures of gVIIA-PLA2 following inhibition with the OPs diisopropylfluorophosphate, sarin, soman and tabun. The sarin and soman complexes displayed a racemic mix of P{sub R} and P{sub S} stereoisomers at the P-chiral center. The tabun complex displayed only the P{sub R} stereoisomer in the crystal. In all cases, the crystal structures contained intact OP adducts that had not aged. Aging refers to a secondary process OP complexes can go through, which dealkylates the nerve agent adduct and results in a form that is highly resistant to either spontaneous or oxime-mediated reactivation. Non-aged OP complexes of the enzyme were corroborated by trypsin digest and matrix-assisted laser desorption ionization mass spectrometry of OP-enzyme complexes. The lack of stereoselectivity of sarin reaction was confirmed by gas chromatography/mass spectrometry using a chiral column to separate and quantitate the unbound stereoisomers of sarin following incubation with enzyme. The structural details and characterization of nascent reactivity of several toxic nerve agents is discussed with a long-term goal of developing gVIIA-PLA2 as a catalytic bioscavenger of OP nerve agents.

  17. Optical Harmonic Generation from Interfaces with Group IV Semiconductors.

    NASA Astrophysics Data System (ADS)

    Bottomley, David John

    Nonlinear optical techniques have been used to investigate the symmetry properties of interfaces between media comprising at least one Group IV semiconductor. Second harmonic generation (SHG) and third harmonic generation (THG) have been performed for s and p polarization states of the fundamental and harmonic beams as a function of sample azimuthal angle at a fixed fundamental wavelength of 775 nm. In addition to these experimental measurements, the thesis contains theoretical calculations of the optical harmonic response from such media with vicinal surfaces, that is surfaces miscut from a low-index face by {<}{~}10^ circ. The phenomenological theory of Sipe, Moss and van Driel (Phys. Rev. B 35, 1129 (1987)) for SHG and THG in reflection from the low-index faces of cubic centrosymmetric media has been extended to all faces of both cubic centrosymmetric and cubic noncentrosymmetric media. This theory is applied in many parts of the thesis to interpreting the symmetry information present in nonlinear optical data. Experimentally, measurements of SHG and THG from vicinal semiconductor wafers have been performed, and using the above theory the wafer orientations have been obtained to within +/-0.1^circ . In addition, the above theory has been applied to achieve an approximate separation of bulk and surface contributions to SHG measurements from vincinal Si(001) and Si(111) surfaces which Sipe et al. showed is not possible on the low-index faces. The SiO_2/Si interface on vicinal Si(001) has been studied with SHG, and evidence has been obtained for the presence of noncentrosymmetric phases of c-SiO_2 at this interface whose relative concentrations are influenced by the oxidation conditions. For oxidation temperatures below 600 ^circC, the SHG data is shown to be consistent with the presence of tridymite at the buried interface, whereas for oxidation at 900^ circC the SHG data is consistent with the presence of cristobalite. Finally, SHG has been measured from odd

  18. Production of Vascular Endothelial Growth Factors from Human Lung Macrophages Induced by Group IIA and Group X Secreted Phospholipases A2

    PubMed Central

    Granata, Francescopaolo; Frattini, Annunziata; Loffredo, Stefania; Staiano, Rosaria I.; Petraroli, Angelica; Ribatti, Domenico; Oslund, Rob; Gelb, Michael H.; Lambeau, Gerard; Marone, Gianni; Triggiani, Massimo

    2010-01-01

    Angiogenesis and lymphangiogenesis mediated by vascular endothelial growth factors (VEGFs) are main features of chronic inflammation and tumors. Secreted phospholipases A2 (sPLA2s) are overexpressed in inflammatory lung diseases and cancer and they activate inflammatory cells by enzymatic and receptor-mediated mechanisms. We investigated the effect of sPLA2s on the production of VEGFs from human macrophages purified from the lung tissue of patients undergoing thoracic surgery. Primary macrophages express VEGF-A, VEGF-B, VEGF-C, and VEGF-D at both mRNA and protein level. Two human sPLA2s (group IIA and group X) induced the expression and release of VEGF-A and VEGF-C from macrophages. Enzymatically-inactive sPLA2s were as effective as the active enzymes in inducing VEGF production. Me-Indoxam and RO092906A, two compounds that block receptor-mediated effects of sPLA2s, inhibited group X-induced release of VEGF-A. Inhibition of the MAPK p38 by SB203580 also reduced sPLA2-induced release of VEGF-A. Supernatants of group X-activated macrophages induced an angiogenic response in chorioallantoic membranes that was inhibited by Me-Indoxam. Stimulation of macrophages with group X sPLA2 in the presence of adenosine analogs induced a synergistic increase of VEGF-A release and inhibited TNF-α production through a cooperation between A2A and A3 receptors. These results demonstrate that sPLA2s induce production of VEGF-A and VEGF-C in human macrophages by a receptor-mediated mechanism independent from sPLA2 catalytic activity. Thus, sPLA2s may play an important role in inflammatory and/or neoplastic angiogenesis and lymphangiogenesis. PMID:20357262

  19. Grouping Children for Instruction in Team Teaching. Module IV.

    ERIC Educational Resources Information Center

    York, L. Jean

    The fourth of seven modules on team teaching, this document deals with grouping children for instruction, in order that teachers may understand the purposes of grouping, the various kinds of grouping, the variables to be considered in choosing a method, the ways grouping can facilitate individualized instruction, and the need for a flexible…

  20. Stimulation of Phospholipase A2 by Toxic Main Group Heavy Metals: Partly Dependent on G-proteins?

    PubMed Central

    Krug, H. F.

    1995-01-01

    Organometals induce platelet aggregation and inorganic metal ions such as Cd2+ or Pb2+ sensitise human blood platelets to aggregating agents and this action is associated with the liberation of arachidonic acid and eicosanoid formation. The same mechanism is observed using human leukaemia cells (HL-60) when treated with MeHgCl or Et3PbCl. The fatty acid liberation within human platelets and HL-60 cells could only be inhibited with phospholipase A2 inhibitors of different specificity. Preincubation of the cells with pertussis toxin reduces the activation induced by Et3PbCl to a great extent. The non-catalytic B subunit, that only mediates the binding of the toxin to the cell membranes, has no effect at all. When summarised, these results suggest that one possible mechanism for the stimulation of phospholipase A2 by Et3PbCl functions via a G-protein dependent pathway. PMID:18472750

  1. The effect of group X secreted phospholipase A2 on fertilization outcome is specific and not mimicked by other secreted phospholipases A2 or progesterone.

    PubMed

    Abi Nahed, Roland; Escoffier, Jessica; Revel, Charlaine; Jeammet, Louise; Payré, Christine; Ray, Pierre F; Hennebicq, Sylviane; Lambeau, Gerard; Arnoult, Christophe

    2014-04-01

    Mouse group X sPLA2 (mGX) is an acrosomal protein playing an important role in fertilization and controlling acrosome reaction (AR) occurring during capacitation. We demonstrated previously that sperm from mGX knock-out mice had a severely impaired fertilization potential in vitro. We also showed that treatment of wild-type sperm with recombinant mGX during capacitation improved fertilization outcome. This interesting property suggests that sPLA2s could be used to improve fertilization in assisted reproductive technologies (ART). However the molecular mechanism explaining the mGX-dependent enhancing effect on fertilization outcome remains unclear so far. Interestingly, like progesterone (P4), mGX is a very potent activator of AR and the role of mGX-induced AR in fertilization outcome was not evaluated so far. To assess the role of sPLA2-induced AR in IVF, we first tested the potency of 9 mouse and 2 human sPLA2s and P4 to trigger AR of mouse sperm. We then tested the ability of 6 of these molecules (mouse Group IIA, mouse Group IID, mouse Group X, human Group V, human Group X and P4) to improve the yield of 2-cell embryos obtained by IVF in mouse. We showed that in the mouse neither P4 nor any of the other sPLA2s tested were able to mimic the IVF improvement produced by mGX-treatment. These results demonstrate that sPLA2s are not commutable in the context of mouse sperm fertility, indicating that their utilisation in other species, is subjected to the identification of probably unique species-specific active sPLA2.

  2. Psychometric Properties of the Generalized Anxiety Disorder Questionnaire for DSM-IV Among Four Racial Groups

    PubMed Central

    Robinson, Christina M.; Klenck, Suzanne C.; Norton, Peter J.

    2010-01-01

    The Generalized Anxiety Disorder Questionnaire-IV (GAD-Q-IV) is a self-report diagnostic measure of generalized anxiety disorder. Previous studies have established the psychometric properties of the GAD-Q-IV revealing excellent diagnostic specificity and sensitivity as well as good test-retest reliability and convergent and discriminant validity (Newman et al., 2002). Recent analyses with other measures of anxiety symptoms have revealed differences across racial or national groups. Given that the GAD-Q-IV was tested primarily on Caucasian (78%) participants, the purpose of this study was to demonstrate the psychometric properties of the GAD-Q-IV across four racial groups: African American, Caucasian, Hispanic/Latino, and Asian. A student sample of 585 undergraduate psychology students completed the GAD-Q-IV as well as other measures of anxiety symptoms. A clinical replication sample was obtained from 188 clinical participants who completed the GAD-Q-IV as part of a larger psychotherapy study. Results indicated excellent and very similar factor structures in the student sample, and similar psychometric properties across both samples across the racial groups. Implications for the use of the GAD-Q-IV across racial groups are discussed. PMID:20830629

  3. Cationic Group-IV pincer-type complexes for polymerization and hydroamination catalysis.

    PubMed

    Luconi, Lapo; Klosin, Jerzy; Smith, Austin J; Germain, Stéphane; Schulz, Emmanuelle; Hannedouche, Jérôme; Giambastiani, Giuliano

    2014-03-21

    Neutral Zr(IV) and Hf(IV) dimethyl complexes stabilized by unsymmetrical dianionic {N,C,N'} pincer ligands have been prepared from their corresponding bis-amido complexes upon treatment with AlMe₃. Their structure consists of a central ó-bonded aryl donor group (C) capable of forming robust M-C bonds with the metal center, enforced by the synergic effect of both the coordination of peripheral donor groups (N) and the chelating rigid structure of the {N,C,N} ligand framework. Such a combination translates into systems having a unique balance between stability and reactivity. These Zr(IV) and Hf(IV) dimethyl complexes were converted in situ into cationic species [M(IV){N⁻,C⁻,N}Me][B(C₆F₅)₄] which are active catalysts for the room temperature (r.t.) intramolecular hydroamination/cyclization of primary and secondary aminoalkenes as well as for the high temperature ethylene-1-octene copolymerizations.

  4. Group V secreted phospholipase A2 is upregulated by IL-4 in human macrophages and mediates phagocytosis via hydrolysis of ethanolamine phospholipids.

    PubMed

    Rubio, Julio M; Rodríguez, Juan P; Gil-de-Gómez, Luis; Guijas, Carlos; Balboa, María A; Balsinde, Jesús

    2015-04-01

    Studies on the heterogeneity and plasticity of macrophage populations led to the identification of two major polarization states: classically activated macrophages or M1, induced by IFN-γ plus LPS, and alternatively activated macrophages, induced by IL-4. We studied the expression of multiple phospholipase A2 enzymes in human macrophages and the effect that polarization of the cells has on their levels. At least 11 phospholipase A2 genes were found at significant levels in human macrophages, as detected by quantitative PCR. None of these exhibited marked changes after treating the cells with IFN-γ plus LPS. However, macrophage treatment with IL-4 led to strong upregulation of the secreted group V phospholipase A2 (sPLA2-V), both at the mRNA and protein levels. In parallel with increasing sPLA2-V expression levels, IL-4-treated macrophages exhibited increased phagocytosis of yeast-derived zymosan and bacteria, and we show that both events are causally related, because cells deficient in sPLA2-V exhibited decreased phagocytosis, and cells overexpressing the enzyme manifested higher rates of phagocytosis. Mass spectrometry analyses of lipid changes in the IL-4-treated macrophages suggest that ethanolamine lysophospholipid (LPE) is an sPLA2-V-derived product that may be involved in regulating phagocytosis. Cellular levels of LPE are selectively maintained by sPLA2-V. By supplementing sPLA2-V-deficient cells with LPE, phagocytosis of zymosan or bacteria was fully restored in IL-4-treated cells. Collectively, our results show that sPLA2-V is required for efficient phagocytosis by IL-4-treated human macrophages and provide evidence that sPLA2-V-derived LPE is involved in the process.

  5. Atomic Layer Epitaxy of Group IV Materials: Surface Processes, Thin Films, Devices and their Characterization

    DTIC Science & Technology

    1993-12-01

    U AD-A274 325 Semiannual Technical Report U Atomic Layer Epitaxy of Group IV Materials: Surface Processes, Thin Films, Devices and Their... Group IV Materials: Surface Processes, Thin 414v001---01 Films, Devices and Their Characterization 1114SS S. AUTHOS) N00179 Robert F. Davis, Salah... Conformal deposition of SiC has been demonstrated within trenches etched into Si(100) wafers. P-type films have also been achieved using Al as a

  6. Platelets release mitochondria serving as substrate for bactericidal group IIA-secreted phospholipase A2 to promote inflammation.

    PubMed

    Boudreau, Luc H; Duchez, Anne-Claire; Cloutier, Nathalie; Soulet, Denis; Martin, Nicolas; Bollinger, James; Paré, Alexandre; Rousseau, Matthieu; Naika, Gajendra S; Lévesque, Tania; Laflamme, Cynthia; Marcoux, Geneviève; Lambeau, Gérard; Farndale, Richard W; Pouliot, Marc; Hamzeh-Cognasse, Hind; Cognasse, Fabrice; Garraud, Olivier; Nigrovic, Peter A; Guderley, Helga; Lacroix, Steve; Thibault, Louis; Semple, John W; Gelb, Michael H; Boilard, Eric

    2014-10-02

    Mitochondrial DNA (mtDNA) is a highly potent inflammatory trigger and is reportedly found outside the cells in blood in various pathologies. Platelets are abundant in blood where they promote hemostasis. Although lacking a nucleus, platelets contain functional mitochondria. On activation, platelets produce extracellular vesicles known as microparticles. We hypothesized that activated platelets could also release their mitochondria. We show that activated platelets release respiratory-competent mitochondria, both within membrane-encapsulated microparticles and as free organelles. Extracellular mitochondria are found in platelet concentrates used for transfusion and are present at higher levels in those that induced acute reactions (febrile nonhemolytic reactions, skin manifestations, and cardiovascular events) in transfused patients. We establish that the mitochondrion is an endogenous substrate of secreted phospholipase A2 IIA (sPLA2-IIA), a phospholipase otherwise specific for bacteria, likely reflecting the ancestral proteobacteria origin of mitochondria. The hydrolysis of the mitochondrial membrane by sPLA2-IIA yields inflammatory mediators (ie, lysophospholipids, fatty acids, and mtDNA) that promote leukocyte activation. Two-photon microscopy in live transfused animals revealed that extracellular mitochondria interact with neutrophils in vivo, triggering neutrophil adhesion to the endothelial wall. Our findings identify extracellular mitochondria, produced by platelets, at the midpoint of a potent mechanism leading to inflammatory responses.

  7. Platelets release mitochondria serving as substrate for bactericidal group IIA-secreted phospholipase A2 to promote inflammation

    PubMed Central

    Boudreau, Luc H.; Duchez, Anne-Claire; Cloutier, Nathalie; Soulet, Denis; Martin, Nicolas; Bollinger, James; Paré, Alexandre; Rousseau, Matthieu; Naika, Gajendra S.; Lévesque, Tania; Laflamme, Cynthia; Marcoux, Geneviève; Lambeau, Gérard; Farndale, Richard W.; Pouliot, Marc; Hamzeh-Cognasse, Hind; Cognasse, Fabrice; Garraud, Olivier; Nigrovic, Peter A.; Guderley, Helga; Lacroix, Steve; Thibault, Louis; Semple, John W.; Gelb, Michael H.

    2014-01-01

    Mitochondrial DNA (mtDNA) is a highly potent inflammatory trigger and is reportedly found outside the cells in blood in various pathologies. Platelets are abundant in blood where they promote hemostasis. Although lacking a nucleus, platelets contain functional mitochondria. On activation, platelets produce extracellular vesicles known as microparticles. We hypothesized that activated platelets could also release their mitochondria. We show that activated platelets release respiratory-competent mitochondria, both within membrane-encapsulated microparticles and as free organelles. Extracellular mitochondria are found in platelet concentrates used for transfusion and are present at higher levels in those that induced acute reactions (febrile nonhemolytic reactions, skin manifestations, and cardiovascular events) in transfused patients. We establish that the mitochondrion is an endogenous substrate of secreted phospholipase A2 IIA (sPLA2-IIA), a phospholipase otherwise specific for bacteria, likely reflecting the ancestral proteobacteria origin of mitochondria. The hydrolysis of the mitochondrial membrane by sPLA2-IIA yields inflammatory mediators (ie, lysophospholipids, fatty acids, and mtDNA) that promote leukocyte activation. Two-photon microscopy in live transfused animals revealed that extracellular mitochondria interact with neutrophils in vivo, triggering neutrophil adhesion to the endothelial wall. Our findings identify extracellular mitochondria, produced by platelets, at the midpoint of a potent mechanism leading to inflammatory responses. PMID:25082876

  8. Quantitative Proteomic Analysis of Venoms from Russian Vipers of Pelias Group: Phospholipases A2 are the Main Venom Components

    PubMed Central

    Kovalchuk, Sergey I.; Ziganshin, Rustam H.; Starkov, Vladislav G.; Tsetlin, Victor I.; Utkin, Yuri N.

    2016-01-01

    Venoms of most Russian viper species are poorly characterized. Here, by quantitative chromato-mass-spectrometry, we analyzed protein and peptide compositions of venoms from four Vipera species (V. kaznakovi, V. renardi, V. orlovi and V. nikolskii) inhabiting different regions of Russia. In all these species, the main components were phospholipases A2, their content ranging from 24% in V. orlovi to 65% in V. nikolskii. Altogether, enzyme content in venom of V. nikolskii reached ~85%. Among the non-enzymatic proteins, the most abundant were disintegrins (14%) in the V. renardi venom, C-type lectin like (12.5%) in V. kaznakovi, cysteine-rich venom proteins (12%) in V. orlovi and venom endothelial growth factors (8%) in V. nikolskii. In total, 210 proteins and 512 endogenous peptides were identified in the four viper venoms. They represented 14 snake venom protein families, most of which were found in the venoms of Vipera snakes previously. However, phospholipase B and nucleotide degrading enzymes were reported here for the first time. Compositions of V. kaznakovi and V. orlovi venoms were described for the first time and showed the greatest similarity among the four venoms studied, which probably reflected close relationship between these species within the “kaznakovi” complex. PMID:27077884

  9. Quantitative Proteomic Analysis of Venoms from Russian Vipers of Pelias Group: Phospholipases A₂ are the Main Venom Components.

    PubMed

    Kovalchuk, Sergey I; Ziganshin, Rustam H; Starkov, Vladislav G; Tsetlin, Victor I; Utkin, Yuri N

    2016-04-12

    Venoms of most Russian viper species are poorly characterized. Here, by quantitative chromato-mass-spectrometry, we analyzed protein and peptide compositions of venoms from four Vipera species (V. kaznakovi, V. renardi, V. orlovi and V. nikolskii) inhabiting different regions of Russia. In all these species, the main components were phospholipases A₂, their content ranging from 24% in V. orlovi to 65% in V. nikolskii. Altogether, enzyme content in venom of V. nikolskii reached ~85%. Among the non-enzymatic proteins, the most abundant were disintegrins (14%) in the V. renardi venom, C-type lectin like (12.5%) in V. kaznakovi, cysteine-rich venom proteins (12%) in V. orlovi and venom endothelial growth factors (8%) in V. nikolskii. In total, 210 proteins and 512 endogenous peptides were identified in the four viper venoms. They represented 14 snake venom protein families, most of which were found in the venoms of Vipera snakes previously. However, phospholipase B and nucleotide degrading enzymes were reported here for the first time. Compositions of V. kaznakovi and V. orlovi venoms were described for the first time and showed the greatest similarity among the four venoms studied, which probably reflected close relationship between these species within the "kaznakovi" complex.

  10. Voltage-dependent sodium (NaV) channels in group IV sensory afferents

    PubMed Central

    Elmslie, Keith S

    2016-01-01

    Patients with intermittent claudication suffer from both muscle pain and an exacerbated exercise pressor reflex. Excitability of the group III and group IV afferent fibers mediating these functions is controlled in part by voltage-dependent sodium (NaV) channels. We previously found tetrodotoxin-resistant NaV1.8 channels to be the primary type in muscle afferent somata. However, action potentials in group III and IV afferent axons are blocked by TTX, supporting a minimal role of NaV1.8 channels. To address these apparent differences in NaV channel expression between axon and soma, we used immunohistochemistry to identify the NaV channels expressed in group IV axons within the gastrocnemius muscle and the dorsal root ganglia sections. Positive labeling by an antibody against the neurofilament protein peripherin was used to identify group IV neurons and axons. We show that >67% of group IV fibers express NaV1.8, NaV1.6, or NaV1.7. Interestingly, expression of NaV1.8 channels in group IV somata was significantly higher than in the fibers, whereas there were no significant differences for either NaV1.6 or NaV1.7. When combined with previous work, our results suggest that NaV1.8 channels are expressed in most group IV axons, but that, under normal conditions, NaV1.6 and/or NaV1.7 play a more important role in action potential generation to signal muscle pain and the exercise pressor reflex. PMID:27385723

  11. Critical role of phospholipase A2 group IID in age-related susceptibility to severe acute respiratory syndrome-CoV infection.

    PubMed

    Vijay, Rahul; Hua, Xiaoyang; Meyerholz, David K; Miki, Yoshimi; Yamamoto, Kei; Gelb, Michael; Murakami, Makoto; Perlman, Stanley

    2015-10-19

    Oxidative stress and chronic low-grade inflammation in the lungs are associated with aging and may contribute to age-related immune dysfunction. To maintain lung homeostasis, chronic inflammation is countered by enhanced expression of proresolving/antiinflammatory factors. Here, we show that age-dependent increases of one such factor in the lungs, a phospholipase A2 (PLA2) group IID (PLA2G2D) with antiinflammatory properties, contributed to worse outcomes in mice infected with severe acute respiratory syndrome-coronavirus (SARS-CoV). Strikingly, infection of mice lacking PLA2G2D expression (Pla2g2d(-/-) mice) converted a uniformly lethal infection to a nonlethal one (>80% survival), subsequent to development of enhanced respiratory DC migration to the draining lymph nodes, augmented antivirus T cell responses, and diminished lung damage. We also observed similar effects in influenza A virus-infected middle-aged Pla2g2d(-/-) mice. Furthermore, oxidative stress, probably via lipid peroxidation, was found to induce PLA2G2D expression in mice and in human monocyte-derived macrophages. Thus, our results suggest that directed inhibition of a single inducible phospholipase, PLA2G2D, in the lungs of older patients with severe respiratory infections is potentially an attractive therapeutic intervention to restore immune function.

  12. Critical role of phospholipase A2 group IID in age-related susceptibility to severe acute respiratory syndrome–CoV infection

    PubMed Central

    Vijay, Rahul; Hua, Xiaoyang; Meyerholz, David K.; Miki, Yoshimi; Yamamoto, Kei; Gelb, Michael; Murakami, Makoto

    2015-01-01

    Oxidative stress and chronic low-grade inflammation in the lungs are associated with aging and may contribute to age-related immune dysfunction. To maintain lung homeostasis, chronic inflammation is countered by enhanced expression of proresolving/antiinflammatory factors. Here, we show that age-dependent increases of one such factor in the lungs, a phospholipase A2 (PLA2) group IID (PLA2G2D) with antiinflammatory properties, contributed to worse outcomes in mice infected with severe acute respiratory syndrome-coronavirus (SARS-CoV). Strikingly, infection of mice lacking PLA2G2D expression (Pla2g2d−/− mice) converted a uniformly lethal infection to a nonlethal one (>80% survival), subsequent to development of enhanced respiratory DC migration to the draining lymph nodes, augmented antivirus T cell responses, and diminished lung damage. We also observed similar effects in influenza A virus–infected middle-aged Pla2g2d−/− mice. Furthermore, oxidative stress, probably via lipid peroxidation, was found to induce PLA2G2D expression in mice and in human monocyte–derived macrophages. Thus, our results suggest that directed inhibition of a single inducible phospholipase, PLA2G2D, in the lungs of older patients with severe respiratory infections is potentially an attractive therapeutic intervention to restore immune function. PMID:26392224

  13. Hydrogen-bond Specific Materials Modification in Group IV Semiconductors

    SciTech Connect

    Tolk, Norman H.; Feldman, L. C.; Luepke, G.

    2015-09-14

    impurity states under transient compression. This research focused on the characterization of photon and ion stimulated hydrogen related defect and impurity reactions and migration in solid state matter, which requires a detailed understanding of the rates and pathways of vibrational energy flow, of the transfer channels and of the coupling mechanisms between local vibrational modes (LVMs) and phonon bath as well as the electronic system of the host material. It should be stressed that researchers at Vanderbilt and William and Mary represented a unique group with a research focus and capabilities for low temperature creation and investigation of such material systems. Later in the program, we carried out a vigorous research effort addressing the roles of defects, interfaces, and dopants on the optical and electronic characteristics of semiconductor crystals, using phonon generation by means of ultrafast coherent acoustic phonon (CAP) spectroscopy, nonlinear characterization using second harmonic generation (SHG), and ultrafast pump-and-probe reflectivity and absorption measurements. This program featured research efforts from hydrogen defects in silicon alone to other forms of defects such as interfaces and dopant layers, as well as other important semiconducting systems. Even so, the emphasis remains on phenomena and processes far from equilibrium, such as hot electron effects and travelling localized phonon waves. This program relates directly to the mission of the Department of Energy. Knowledge of the rates and pathways of vibrational energy flow in condensed matter is critical for understanding dynamical processes in solids including electronically, optically and thermally stimulated defect and impurity reactions and migration. The ability to directly probe these pathways and rates allows tests of theory and scaling laws at new levels of precision. Hydrogen embedded in model crystalline semiconductors and metal oxides is of particular interest, since the associated

  14. Effect of NGF on the subcellular localization of group IIA secretory phospholipase A(2) (GIIA) in PC12 cells: role in neuritogenesis.

    PubMed

    Ferrini, M; Nardicchi, V; Mannucci, R; Arcuri, C; Nicoletti, I; Donato, R; Goracci, G

    2010-12-01

    Phospholipases A(2) (PLA(2)s) are involved in neuritogenesis but the identity of the isoforms(s) contributing to this process is still not defined. Several reports have focused on secretory PLA(2)s (sPLA(2)) as the administration of exogenous sPLA(2)s to PC12 neuronal cells stimulates neurite outgrowth. The present study demonstrates that the endogenous group IIA sPLA(2) (GIIA), constitutively expressed in mammalian neural cells, changes its subcellular localization when PC12 cells are induced to differentiate by NGF treatment. Indeed, confocal analysis showed a time-dependent accumulation of GIIA in growth cones and neurite tips. Under identical conditions the subcellular distribution of another isoform (GV) was unaffected by NGF. Contrary to GX, another sPLA(2) isoform expressed by PC12 cells, the contribution of GIIA to neuritogenesis does not require its release in the extracellular medium.

  15. Crystal structures of brain group-VIII phospholipase A2 in nonaged complexes with the organophosphorus nerve agents soman and sarin.

    PubMed

    Epstein, Todd M; Samanta, Uttamkumar; Kirby, Stephen D; Cerasoli, Douglas M; Bahnson, Brian J

    2009-04-21

    Insecticide and nerve agent organophosphorus (OP) compounds are potent inhibitors of the serine hydrolase superfamily of enzymes. Nerve agents, such as sarin, soman, tabun, and VX exert their toxicity by inhibiting human acetycholinesterase at nerve synapses. Following the initial phosphonylation of the active site serine, the enzyme may reactivate spontaneously or through reaction with an appropriate nucleophilic oxime. Alternatively, the enzyme-nerve agent complex can undergo a secondary process, called "aging", which dealkylates the nerve agent adduct and results in a product that is highly resistant to reactivation by any known means. Here we report the structures of paraoxon, soman, and sarin complexes of group-VIII phospholipase A2 from bovine brain. In each case, the crystal structures indicate a nonaged adduct; a stereoselective preference for binding of the P(S)C(S) isomer of soman and the P(S) isomer of sarin was also noted. The stability of the nonaged complexes was corroborated by trypsin digest and electrospray ionization mass spectrometry, which indicates nonaged complexes are formed with diisopropylfluorophosphate, soman, and sarin. The P(S) stereoselectivity for reaction with sarin was confirmed by reaction of racemic sarin, followed by gas chromatography/mass spectrometry using a chiral column to separate and quantitate each stereoisomer. The P(S) stereoisomers of soman and sarin are known to be the more toxic stereoisomers, as they react preferentially to inhibit human acetylcholinesterase. The results obtained for nonaged complexes of group-VIII phospholipase A2 are compared to those obtained for other serine hydrolases and discussed to partly explain determinants of OP aging. Furthermore, structural insights can now be exploited to engineer variant versions of this enzyme with enhanced nerve agent binding and hydrolysis functions.

  16. A phospholipid substrate molecule residing in the membrane surface mediates opening of the lid region in group IVA cytosolic phospholipase A2.

    PubMed

    Burke, John E; Hsu, Yuan-Hao; Deems, Raymond A; Li, Sheng; Woods, Virgil L; Dennis, Edward A

    2008-11-07

    The Group IVA (GIVA) phospholipase A(2) associates with natural membranes in response to an increase in intracellular Ca(2+) along with increases in certain lipid mediators. This enzyme associates with the membrane surface as well as binding a single phospholipid molecule in the active site for catalysis. Employing deuterium exchange mass spectrometry, we have identified the regions of the protein binding the lipid surface and conformational changes upon a single phospholipid binding in the absence of a lipid surface. Experiments were carried out using natural palmitoyl arachidonyl phosphatidylcholine vesicles with the intact GIVA enzyme as well as the isolated C2 and catalytic domains. Lipid binding produced changes in deuterium exchange in eight different regions of the protein. The regions with decreased exchange included Ca(2+) binding loop one, which has been proposed to penetrate the membrane surface, and a charged patch of residues, which may be important in interacting with the polar head groups of phospholipids. The regions with an increase in exchange are all located either in the hydrophobic core underneath the lid region or near the lid and hinge regions from 403 to 457. Using the GIVA phospholipase A(2) irreversible inhibitor methyl-arachidonyl fluorophosphonate, we were able to isolate structural changes caused only by pseudo-substrate binding. This produced results that were very similar to natural lipid binding in the presence of a lipid interface with the exception of the C2 domain and region 466-470. This implies that most of the changes seen in the catalytic domain are due to a substrate-mediated, not interface-mediated, lid opening, which exposes the active site to water. Finally experiments carried out with inhibitor plus phospholipid vesicles showed decreases at the C2 domain as well as charged residues on the putative membrane binding surface of the catalytic domain revealing the binding sites of the enzyme to the lipid surface.

  17. Group X Secretory Phospholipase A2 Regulates the Expression of Steroidogenic Acute Regulatory Protein (StAR) in Mouse Adrenal Glands*

    PubMed Central

    Shridas, Preetha; Bailey, William M.; Boyanovsky, Boris B.; Oslund, Rob C.; Gelb, Michael H.; Webb, Nancy R.

    2010-01-01

    We developed C57BL/6 mice with targeted deletion of group X secretory phospholipase A2 (GX KO). These mice have ∼80% higher plasma corticosterone concentrations compared with wild-type (WT) mice under both basal and adrenocorticotropic hormone (ACTH)-induced stress conditions. This increased corticosterone level was not associated with increased circulating ACTH or a defect in the hypothalamic-pituitary axis as evidenced by a normal response to dexamethasone challenge. Primary cultures of adrenal cells from GX KO mice exhibited significantly increased corticosteroid secretion compared with WT cells. Conversely, overexpression of GX secretory phospholipase A2 (sPLA2), but not a catalytically inactive mutant form of GX sPLA2, significantly reduced steroid production 30–40% in Y1 mouse adrenal cell line. This effect was reversed by the sPLA2 inhibitor, indoxam. Silencing of endogenous M-type receptor expression did not restore steroid production in GX sPLA2-overexpressing Y1 cells, ruling out a role for this sPLA2 receptor in this regulatory process. Expression of steroidogenic acute regulatory protein (StAR), the rate-limiting protein in corticosteroid production, was ∼2-fold higher in adrenal glands of GX KO mice compared with WT mice, whereas StAR expression was suppressed in Y1 cells overexpressing GX sPLA2. Results from StAR-promoter luciferase reporter gene assays indicated that GX sPLA2 antagonizes StAR promoter activity and liver X receptor-mediated StAR promoter activation. In summary, GX sPLA2 is expressed in mouse adrenal glands and functions to negatively regulate corticosteroid synthesis, most likely by negatively regulating StAR expression. PMID:20421306

  18. Group X secretory phospholipase A2 regulates the expression of steroidogenic acute regulatory protein (StAR) in mouse adrenal glands.

    PubMed

    Shridas, Preetha; Bailey, William M; Boyanovsky, Boris B; Oslund, Rob C; Gelb, Michael H; Webb, Nancy R

    2010-06-25

    We developed C57BL/6 mice with targeted deletion of group X secretory phospholipase A(2) (GX KO). These mice have approximately 80% higher plasma corticosterone concentrations compared with wild-type (WT) mice under both basal and adrenocorticotropic hormone (ACTH)-induced stress conditions. This increased corticosterone level was not associated with increased circulating ACTH or a defect in the hypothalamic-pituitary axis as evidenced by a normal response to dexamethasone challenge. Primary cultures of adrenal cells from GX KO mice exhibited significantly increased corticosteroid secretion compared with WT cells. Conversely, overexpression of GX secretory phospholipase A(2) (sPLA(2)), but not a catalytically inactive mutant form of GX sPLA(2), significantly reduced steroid production 30-40% in Y1 mouse adrenal cell line. This effect was reversed by the sPLA(2) inhibitor, indoxam. Silencing of endogenous M-type receptor expression did not restore steroid production in GX sPLA(2)-overexpressing Y1 cells, ruling out a role for this sPLA(2) receptor in this regulatory process. Expression of steroidogenic acute regulatory protein (StAR), the rate-limiting protein in corticosteroid production, was approximately 2-fold higher in adrenal glands of GX KO mice compared with WT mice, whereas StAR expression was suppressed in Y1 cells overexpressing GX sPLA(2). Results from StAR-promoter luciferase reporter gene assays indicated that GX sPLA(2) antagonizes StAR promoter activity and liver X receptor-mediated StAR promoter activation. In summary, GX sPLA(2) is expressed in mouse adrenal glands and functions to negatively regulate corticosteroid synthesis, most likely by negatively regulating StAR expression.

  19. Cationic Group-IV pincer-type complexes for polymerization and hydroamination catalysis.

    PubMed

    Luconi, Lapo; Klosin, Jerzy; Smith, Austin J; Germain, Stéphane; Schulz, Emmanuelle; Hannedouche, Jérôme; Giambastiani, Giuliano

    2013-12-07

    Neutral Zr(IV) and Hf(IV) dimethyl complexes stabilized by unsymmetrical dianionic {N,C,N'} pincer ligands have been prepared from their corresponding bis-amido complexes upon treatment with AlMe3. Their structure consists of a central σ-bonded aryl donor group (C) capable of forming robust M-C bonds with the metal center, enforced by the synergic effect of both the coordination of peripheral donor groups (N) and the chelating rigid structure of the {N,C,N} ligand framework. Such a combination translates into systems having a unique balance between stability and reactivity. These Zr(IV) and Hf(IV) dimethyl complexes were converted in situ into cationic species [M(IV){N(-),C(-),N}Me][B(C6F5)4] which are active catalysts for the room temperature (r.t.) intramolecular hydroamination/cyclization of primary and secondary aminoalkenes as well as for the high temperature ethylene-1-octene copolymerizations.

  20. CDC Group IV c-2: a New Ralstonia Species Close to Ralstonia eutropha

    PubMed Central

    Moissenet, Didier; Goujon, Christophe P.; Garbarg-Chenon, Antoine; Vu-Thien, Hoang

    1999-01-01

    CDC group IV c-2, an environmental gram-negative bacillus recently proposed for inclusion in the genus Ralstonia, has been isolated in several human infections. Biochemical characterization and 16S ribosomal DNA (rDNA) sequencing with phylogenetic analysis were used to characterize eight clinical isolates and four type strains. Other typing tools, such as pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) analysis, were also used. PFGE typing of clinical isolates was unsuccessful because the DNA was degraded, and RAPD analysis was poorly discriminatory. In contrast, the type strains were clearly distinguished with both PFGE and RAPD analysis. All of the 16S rDNA sequences were identical. Comparison of the 16S rDNA sequences to the GenBank sequences showed that they were consistent with CDC group IV c-2 belonging to the genus Ralstonia. The closest matches were obtained with Ralstonia eutropha. However, four differences in 32 biochemical tests separated R. eutropha from CDC group IV c-2, which suggests that CDC group IV c-2 is a new species of the genus Ralstonia. PMID:10325323

  1. Serotype IV Sequence Type 468 Group B Streptococcus Neonatal Invasive Disease, Minnesota, USA

    PubMed Central

    Teatero, Sarah; Ferrieri, Patricia

    2016-01-01

    To further understand the emergence of serotype IV group B Streptococcus (GBS) invasive disease, we used whole-genome sequencing to characterize 3 sequence type 468 strains isolated from neonates in Minnesota, USA. We found that strains of tetracycline-resistant sequence type 468 GBS have acquired virulence genes from a putative clonal complex 17 GBS donor by recombination. PMID:27767922

  2. Surface Chemistry Exchange of Alloyed Germanium Nanocrystals: A Pathway Toward Conductive Group IV Nanocrystal Films.

    PubMed

    Ruddy, Daniel A; Erslev, Peter T; Habas, Susan E; Seabold, Jason A; Neale, Nathan R

    2013-02-07

    We present an expansion of the mixed-valence iodide reduction method for the synthesis of Ge nanocrystals (NCs) to incorporate low levels (∼1 mol %) of groups III, IV, and V elements to yield main-group element-alloyed Ge NCs (Ge1-xEx NCs). Nearly every main-group element (E) that surrounds Ge on the periodic table (Al, P, Ga, As, In, Sn, and Sb) may be incorporated into Ge1-xEx NCs with remarkably high E incorporation into the product (>45% of E added to the reaction). Importantly, surface chemistry modification via ligand exchange allowed conductive films of Ge1-xEx NCs to be prepared, which exhibit conductivities over large distances (25 μm) relevant to optoelectronic device development of group IV NC thin films.

  3. Autonomic responses to exercise: group III/IV muscle afferents and fatigue.

    PubMed

    Amann, Markus; Sidhu, Simranjit K; Weavil, Joshua C; Mangum, Tyler S; Venturelli, Massimo

    2015-03-01

    Group III and IV muscle afferents originating in exercising limb muscle play a significant role in the development of fatigue during exercise in humans. Feedback from these sensory neurons to the central nervous system (CNS) reflexively increases ventilation and central (cardiac output) and peripheral (limb blood flow) hemodynamic responses during exercise and thereby assures adequate muscle blood flow and O2 delivery. This response depicts a key factor in minimizing the rate of development of peripheral fatigue and in optimizing aerobic exercise capacity. On the other hand, the central projection of group III/IV muscle afferents impairs performance and limits the exercising human via its diminishing effect on the output from spinal motoneurons which decreases voluntary muscle activation (i.e. facilitates central fatigue). Accumulating evidence from recent animal studies suggests the existence of two subtypes of group III/IV muscle afferents. While one subtype only responds to physiological and innocuous levels of endogenous intramuscular metabolites (lactate, ATP, protons) associated with 'normal', predominantly aerobic exercise, the other subtype only responds to higher and concurrently noxious levels of metabolites present in muscle during ischemic contractions or following, for example, hypertonic saline infusions. This review discusses the mechanisms through which group III/IV muscle afferent feedback mediates both central and peripheral fatigue in exercising humans. We also briefly summarize the accumulating evidence from recent animal and human studies documenting the existence of two subtypes of group III/IV muscle afferents and the relevance of this discovery to the interpretation of previous work and the design of future studies.

  4. Role of group V phospholipase A2 in zymosan-induced eicosanoid generation and vascular permeability revealed by targeted gene disruption*

    PubMed Central

    Satake, Yoshiyuki; Diaz, Bruno L.; Balestrieri, Barbara; Lam, Bing K.; Kanaoka, Yoshihide; Grusby, Michael J.; Arm, Jonathan P.

    2005-01-01

    SUMMARY Conclusions regarding the contribution of low molecular weight secretory phospholipase A2 (sPLA2) enzymes in eicosanoid generation have relied on data obtained from transfected cells or the use of inhibitors that fail to discriminate between individual members of the large family of mammalian sPLA2 enzymes. To elucidate the role of group V sPLA2, we used targeted gene disruption to generate mice lacking this enzyme. Zymosan-induced generation of leukotriene C4 and prostaglandin E2 was attenuated ~50% in peritoneal macrophages from group V sPLA2-null mice compared to macrophages from wild-type littermates. Furthermore, the early phase of plasma exudation in response to intraperitoneal injection of zymosan and the accompanying in vivo generation of cysteinyl leukotrienes were markedly attenuated in group V sPLA2-null mice compared to wild-type controls. These data provide clear evidence of a role for group V sPLA2 in regulating eicosanoid generation in response to an acute innate stimulus of the immune response both in vitro and in vivo, suggesting a role for this enzyme in innate immunity. PMID:14761945

  5. Identification of an autoantigen on the surface of apoptotic human T cells as a new protein interacting with inflammatory group IIA phospholipase A2.

    PubMed

    Boilard, Eric; Bourgoin, Sylvain G; Bernatchez, Chantale; Surette, Marc E

    2003-10-15

    One of the most studied secreted phospholipases A2 (sPLA2), the group IIA sPLA2, is found at high levels in inflammatory fluids of patients with autoimmune diseases. A characteristic of group IIA sPLA2 is its preference for negatively charged phospholipids, which become exposed on the extracellular leaflet of apoptotic cell membranes. We recently showed that low molecular weight heparan sulfate proteoglycans (HSPGs) and uncharacterized detergent-insoluble binding site(s) contribute to the enhanced binding of human group IIA PLA2 (hGIIA) to apoptotic human T cells. Using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry we now identify vimentin as the major HSPG-independent binding protein of hGIIA on apoptotic primary T lymphocytes. Vimentin is partially exposed on the surface of apoptotic T cells and binds hGIIA via its rod domain in a calcium-independent manner. Studies with hGIIA mutants showed that specific motifs in the interfacial binding surface are involved in the interaction with vimentin. The sPLA2 inhibitor LY311727, but not heparin, inhibited this interaction. In contrast, heparin but not LY311727 abrogated the binding of hGIIA to cellular HSPGs. Importantly, vimentin does not inhibit the catalytic activity of hGIIA. Altogether, the results show that vimentin, in conjunction with HSPGs, contributes to the enhanced binding of hGIIA to apoptotic T cells.

  6. Bifactor Model of WISC-IV: Applicability and Measurement Invariance in Low and Normal IQ Groups.

    PubMed

    Gomez, Rapson; Vance, Alasdair; Watson, Shaun

    2016-09-05

    This study examined the applicability and measurement invariance of the bifactor model of the 10 Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) core subtests in groups of children and adolescents (age range from 6 to 16 years) with low (IQ ≤79; N = 229; % male = 75.9) and normal (IQ ≥80; N = 816; % male = 75.0) IQ scores. Results supported this model in both groups, and there was good support for measurement invariance for this model across these groups. For all participants together, the omega hierarchical and explained common variance (ECV) values were high for the general factor and low to negligible for the specific factors. Together, the findings favor the use of the Full Scale IQ (FSIQ) scores of the WISC-IV, but not the subscale index scores. (PsycINFO Database Record

  7. Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III, and IV

    PubMed Central

    Brunt, Jason; van Vliet, Arnoud H. M.; van den Bos, Fédor; Carter, Andrew T.; Peck, Michael W.

    2016-01-01

    Clostridium botulinum is a highly dangerous pathogen that forms very resistant endospores that are ubiquitous in the environment, and which, under favorable conditions germinate to produce vegetative cells that multiply and form the exceptionally potent botulinum neurotoxin. To improve the control of botulinum neurotoxin-forming clostridia, it is important to understand the mechanisms involved in spore germination. Here we present models for spore germination in C. botulinum based on comparative genomics analyses, with C. botulinum Groups I and III sharing similar pathways, which differ from those proposed for C. botulinum Groups II and IV. All spores germinate in response to amino acids interacting with a germinant receptor, with four types of germinant receptor identified [encoded by various combinations of gerA, gerB, and gerC genes (gerX)]. There are three gene clusters with an ABC-like configuration; ABC [gerX1], ABABCB [gerX2] and ACxBBB [gerX4], and a single CA-B [gerX3] gene cluster. Subtypes have been identified for most germinant receptor types, and the individual GerX subunits of each cluster show similar grouping in phylogenetic trees. C. botulinum Group I contained the largest variety of gerX subtypes, with three gerX1, three gerX2, and one gerX3 subtypes, while C. botulinum Group III contained two gerX1 types and one gerX4. C. botulinum Groups II and IV contained a single germinant receptor, gerX3 and gerX1, respectively. It is likely that all four C. botulinum Groups include a SpoVA channel involved in dipicolinic acid release. The cortex-lytic enzymes present in C. botulinum Groups I and III appear to be CwlJ and SleB, while in C. botulinum Groups II and IV, SleC appears to be important. PMID:27840626

  8. NGF induces the expression of group IIA secretory phospholipase A2 in PC12 cells: the newly synthesized enzyme is addressed to growing neurites.

    PubMed

    Nardicchi, Vincenza; Ferrini, Monica; Pilolli, Francesca; Angeli, Emanuela Biagioni; Persichetti, Emanuele; Beccari, Tommaso; Mannucci, Roberta; Arcuri, Cataldo; Donato, Rosario; Dorman, Robert V; Goracci, Gianfrancesco

    2014-08-01

    We proposed that group IIA secretory phospholipase A(2) (GIIA) participates in neuritogenesis based on our observations that the enzyme migrates to growth cones and neurite tips when PC12 cells are induced to differentiate by nerve growth factor (NGF) (Ferrini et al., Neurochem Res 35:2168-2174, 2010). The involvement of other secretory PLA(2) isoforms in neuronal development has been suggested by others but through different mechanisms. In the present study, we compared the subcellular distribution of GIIA and group X sPLA(2) (GX) after stimulation of PC12 cells with NGF. We found that GIIA, but not GX, localized at the neuritic tips after treatment with NGF, as demonstrated by immunofluorescence analysis. We also found that NGF stimulated the expression and the activity of GIIA. In addition, NGF induced the expressed myc-tagged GIIA protein to migrate to neurite tips in its active form. We propose that GIIA expression, activity, and subcellular localization is regulated by NGF and that the enzyme may participate in neuritogenesis through intracellular mechanisms, most likely by facilitating the remodelling of glycerophospholipid molecular species by deacylation-reacylation reactions necessary for the incorporation of polyunsaturated fatty acids.

  9. Generalization of Weber's adiabatic bond charge model to amorphous group IV semiconductors

    NASA Astrophysics Data System (ADS)

    Winer, K.; Wooten, F.

    1984-11-01

    The generalization of Weber's adiabatic bond charge model to amorphous group IV semiconductors is described. Methods of relaxing the coordinates to their equilibrium configuration and of calculating the dynamical matrix for the phonon spectra are given. Particular emphasis is given to the optimization of the Coulomb subroutines required in this model. Estimates of computation time are included for the calculation of equilibrium configuration on a Cray computer.

  10. Inhibition of Group IIA Secretory Phospholipase A2 and its Inflammatory Reactions in Mice by Ethanolic Extract of Andrographis paniculata, a Well-known Medicinal Food

    PubMed Central

    Kishore, V.; Yarla, N. S.; Zameer, F.; Nagendra Prasad, M. N.; Santosh, M. S.; More, S. S.; Rao, D. G.; Dhananjaya, Bhadrapura Lakkappa

    2016-01-01

    Andrographis paniculata Nees is an important medicinal plant found in the tropical regions of the world, which has been traditionally used in Indian and Chinese medicinal systems. It is also used as medicinal food. A. paniculata is found to exhibit anti-inflammatory activities; however, its inhibitory potential on inflammatory Group IIA phospholipases A2 (PLA2) and its associated inflammatory reactions are not clearly understood. The aim of the present study is to evaluate the inhibitory/neutralizing potential of ethanolic extract of A. paniculata on the isolated inflammatory PLA2 (VRV-PL-VIIIa) from Daboii rusellii pulchella (belonging to Group IIA inflammatory secretory PLA2 [sPLA2]) and its associated edema-induced activities in Swiss albino mice. A. paniculata extract dose dependently inhibited the Group IIA sPLA2 enzymatic activity with an IC50 value of 10.3 ± 0.5 μg/ml. Further, the extract dose dependently inhibited the edema formation, when co-injected with enzyme indicating that a strong correlation exists between lipolytic and pro-inflammatory activities of the enzyme. In conclusion, results of this study shows that the ethanolic extract of A. paniculata effectively inhibits Group IIA sPLA2 and its associated inflammatory activities, which substantiate its anti-inflammatory properties. The results of the present study warranted further studies to develop bioactive compound (s) in ethanolic extract of A. paniculata as potent therapeutic agent (s) for inflammatory diseases. SUMMARY This study emphasis the anti-inflammatory effect of A. paniculata by inhibiting the inflammatory Group IIA sPLA2 and its associated inflammatory activities such as edema. It was found that there is a strong correlation between lipolytic activity and pro-inflammatory activity inhibition. Therefore, the study suggests that the extract processes potent anti-inflammatory agents, which could be developed as a potential therapeutic agent against inflammatory and related diseases

  11. Spectroscopic investigation of phenolic groups ionization in the vipoxin neurotoxic phospholipase A 2: comparison with the X-ray structure in the region of the tyrosyl residues

    NASA Astrophysics Data System (ADS)

    Georgieva, Dessislava Nikolova; Genov, Nicolay; Rajashankar, Kanagalaghatta R.; Aleksiev, Boris; Betzel, Christian

    1998-12-01

    The neurotoxin vipoxin is the major lethal component of the venom of Vipera ammodites meridionalis, the most toxic snake in Europe. It is a complex between a toxic phospholipase A 2 (PLA 2) and a non-toxic protein inhibitor (Inh). Tyrosyl residues are involved in the catalytic site (Tyr 52 and 73) and in the substrate binding (Tyr 22). Spectroscopic studies demonstrated differences in the ionization behavior of the various phenolic hydroxyl groups in the toxic PLA 2. The tyrosyl side chains of the enzyme can be classified into three groups: (a) three phenolic hydroxyls are accessible to the solvent and titrate normally, with a p Keff=10.45; (b) three residues are partially 'buried' and participate in hydrogen bonds with neighboring functional groups. They titrate anomalously with a p Keff=12.17; (c) two tyrosines with a p Keff=13.23 are deeply 'buried' in the hydrophobic interior of PLA 2. They became accessible to the titrating agent only after alkaline denaturation of the protein molecule. The spectroscopic data are related to the X-ray structure of the vipoxin PLA 2. The refined model was investigated in the region of the tyrosyl side chains. The accessible surface area of each tyrosyl residue and each phenolic hydroxyl group was calculated. A good correlation between the spectrophotometric and the crystallographic data was observed. The ionization behavior of the phenolic groups is explained by peculiarities of the protein three-dimensional structure and the participation of tyrosines in the catalytic site hydrogen bond network. Attempts are made to assign the calculated p Keff values to individual residues. The high degree of 'exposure' on the protein surface of Tyr 22 and 75 is probably important for their function as parts of the substrate binding and pharmacological sites.

  12. Transferable tight binding model for strained group IV and III-V heterostructures

    NASA Astrophysics Data System (ADS)

    Tan, Yaohua; Povolotskyi, Micheal; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

    Modern semiconductor devices have reached critical device dimensions in the range of several nanometers. For reliable prediction of device performance, it is critical to have a numerical efficient model that are transferable to material interfaces. In this work, we present an empirical tight binding (ETB) model with transferable parameters for strained IV and III-V group semiconductors. The ETB model is numerically highly efficient as it make use of an orthogonal sp3d5s* basis set with nearest neighbor inter-atomic interactions. The ETB parameters are generated from HSE06 hybrid functional calculations. Band structures of strained group IV and III-V materials by ETB model are in good agreement with corresponding HSE06 calculations. Furthermore, the ETB model is applied to strained superlattices which consist of group IV and III-V elements. The ETB model turns out to be transferable to nano-scale hetero-structure. The ETB band structures agree with the corresponding HSE06 results in the whole Brillouin zone. The ETB band gaps of superlattices with common cations or common anions have discrepancies within 0.05eV.

  13. Ectopically Expressed Pro-group X Secretory Phospholipase A2 Is Proteolytically Activated in Mouse Adrenal Cells by Furin-like Proprotein Convertases

    PubMed Central

    Layne, Joseph D.; Shridas, Preetha; Webb, Nancy R.

    2015-01-01

    Group X secretory phospholipase A2 (GX sPLA2) hydrolyzes mammalian cell membranes, liberating free fatty acids and lysophospholipids. GX sPLA2 is produced as a pro-enzyme (pro-GX sPLA2) that contains an N-terminal 11-amino acid propeptide ending in a dibasic motif, suggesting cleavage by a furin-like proprotein convertase (PC). Although propeptide cleavage is clearly required for enzymatic activity, the protease(s) responsible for pro-GX sPLA2 activation have not been identified. We previously reported that GX sPLA2 negatively regulates adrenal glucocorticoid production, likely by suppressing liver X receptor-mediated activation of steroidogenic acute regulatory protein expression. In this study, using a FLAG epitope-tagged pro-GX sPLA2 expression construct (FLAG-pro-GX sPLA2), we determined that adrenocorticotropic hormone (ACTH) enhanced FLAG-pro-GX sPLA2 processing and phospholipase activity secreted by Y1 adrenal cells. ACTH increased the expression of furin and PCSK6, but not other members of the PC family, in Y1 cells. Overexpression of furin and PCSK6 in HEK 293 cells significantly enhanced FLAG-pro-GX sPLA2 processing, whereas siRNA-mediated knockdown of both PCs almost completely abolished FLAG-pro-GX sPLA2 processing in Y1 cells. Expression of either furin or PCSK6 enhanced the ability of GX sPLA2 to suppress liver X receptor reporter activity. The PC inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethyl ketone significantly suppressed FLAG-pro-GX sPLA2 processing and sPLA2 activity in Y1 cells, and it significantly attenuated GX sPLA2-dependent inhibition of steroidogenic acute regulatory protein expression and progesterone production. These findings provide strong evidence that pro-GX sPLA2 is a substrate for furin and PCSK6 proteolytic processing and define a novel mechanism for regulating corticosteroid production in adrenal cells. PMID:25623068

  14. Effects of Statins and Xuezhikang on the Expression of Secretory Phospholipase A2, Group IIA in Rat Vascular Smooth Muscle Cells.

    PubMed

    Xie, Qiang; Zhang, Dan

    2017-02-07

    Atherosclerosis is a multifactorial vascular disease characterized by formation of inflammatory lesions. Secretory phospholipase A2, group IIA (sPLA2-IIA) is involved in this process and plays a critical role. However, the exact role of sPLA2-IIA in cardiovascular inflammation is more complicated and remains unclear. Furthermore, both statins and Xuezhikang (XZK) are widely used in the prevention and treatment of cardiovascular disease risk because of their pleiotropic effects on the cardiovascular system. However, their effects on sPLA2-IIA are still controversial. We investigated the regulation of sPLA2-IIA by rat thoracic aorta smooth muscle cells (VSMCs) in culture. Cells were first incubated with IL-1β alone to induce expression of sPLA2-IIA and then treated with several concentrations of statins or XZK for different times in the absence or presence of IL-1β. We tested the expression of sPLA2-IIA, including sPLA2-IIA mRNA, protein, as well as activity. We found that statins or IL-1β increase the expression of sPLA2-IIA in VSMCs and the effect is based on a synergetic relationship between them. However, for the first time, we observed that XZK effectively reduces sPLA2-IIA expression in IL-1β-treated VSMCs. Our findings may shine a new light on the clinical use of XZK and statins in the prevention and treatment of atherosclerosis-related thrombosis.

  15. L-type voltage-dependent calcium channel is involved in the snake venom group IA secretory phospholipase A2-induced neuronal apoptosis.

    PubMed

    Yagami, Tatsurou; Yamamoto, Yasuhiro; Kohma, Hiromi; Nakamura, Tsutomu; Takasu, Nobuo; Okamura, Noboru

    2013-03-01

    Snake venom group IA secretory phospholipase A2 (sPLA2-IA) is known as a neurotoxin. Snake venom sPLA2s are neurotoxic in vivo and in vitro, causing synergistic neurotoxicity to cortical cultures when applied with toxic concentrations of glutamate. However, it has not yet been cleared sufficiently how sPLA2-IA exerts neurotoxicity. Here, we found sPLA2-IA induced neuronal cell death in a concentration-dependent manner. This death was a delayed response requiring a latent time for 6h. sPLA2-IA-induced neuronal cell death was accompanied with apoptotic blebbing, condensed chromatin, and fragmented DNA, exhibiting apoptotic features. NMDA receptor blockers suppressed the neurotoxicity of sPLA2-IA, but an AMPA receptor blocker did not. Interestingly, L-type voltage-dependent Ca(2+) channel (L-VDCC) blocker significantly protected neurons from the sPLA2-IA-induced apoptosis. On the other hand, neither N-VDCC blockers nor P/Q-VDCC blocker did. In conclusion, we demonstrated that sPLA2-IA induced neuronal cell death via apoptosis. Furthermore, the present study suggests that not only NMDA receptor but also L-VDCC contributed to the neurotoxicity of snake venom sPLA2-IA.

  16. Computational prediction of two-dimensional group-IV mono-chalcogenides

    SciTech Connect

    Singh, Arunima K.; Hennig, Richard G.

    2014-07-28

    Density functional calculations determine the structure, stability, and electronic properties of two-dimensional materials in the family of group-IV monochalcogenides, MX (M = Ge, Sn, Pb; X = O, S, Se, Te). Calculations with a van der Waals functional show that the two-dimensional IV-VI compounds are most stable in either a highly distorted NaCl-type structure or a single-layer litharge type tetragonal structure. Their formation energies are comparable to single-layer MoS{sub 2}, indicating the ease of mechanical exfoliation from their layered bulk structures. The phonon spectra confirm their dynamical stability. Using the hybrid HSE06 functional, we find that these materials are semiconductors with bandgaps that are generally larger than for their bulk counterparts due to quantum confinement. The band edge alignments of monolayer group IV-VI materials reveal several type-I and type-II heterostructures, suited for optoelectronics and solar energy conversion.

  17. Mice deficient in Group VIB phospholipase A2 (iPLA2γ) exhibit relative resistance to obesity and metabolic abnormalities induced by a Western diet

    PubMed Central

    Song, Haowei; Wohltmann, Mary; Bao, Shunzhong; Ladenson, Jack H.; Semenkovich, Clay F.

    2010-01-01

    Phospholipases A2 (PLA2) play important roles in metabolic processes, and the Group VI PLA2 family is comprised of intracellular enzymes that do not require Ca2+ for catalysis. Mice deficient in Group VIA PLA2 (iPLA2β) develop more severe glucose intolerance than wild-type (WT) mice in response to dietary stress. Group VIB PLA2 (iPLA2γ) is a related enzyme distributed in membranous organelles, including mitochondria, and iPLA2γ knockout (KO) mice exhibit altered mitochondrial morphology and function. We have compared metabolic responses of iPLA2γ-KO and WT mice fed a Western diet (WD) with a high fat content. We find that KO mice are resistant to WD-induced increases in body weight and adiposity and in blood levels of cholesterol, glucose, and insulin, even though WT and KO mice exhibit similar food consumption and dietary fat digestion and absorption. KO mice are also relatively resistant to WD-induced insulin resistance, glucose intolerance, and altered patterns of fat vs. carbohydrate fuel utilization. KO skeletal muscle exhibits impaired mitochondrial β-oxidation of fatty acids, as reflected by accumulation of larger amounts of long-chain acylcarnitine (LCAC) species in KO muscle and liver compared with WT in response to WD feeding. This is associated with increased urinary excretion of LCAC and much reduced deposition of triacylglycerols in liver by WD-fed KO compared with WT mice. The iPLA2γ-deficient genotype thus results in a phenotype characterized by impaired mitochondrial oxidation of fatty acids and relative resistance to the metabolic abnormalities induced by WD. PMID:20179248

  18. The origin of electronic band structure anomaly in topological crystalline insulator group-IV tellurides

    NASA Astrophysics Data System (ADS)

    Ye, Zhen-Yu; Deng, Hui-Xiong; Wu, Hui-Zhen; Li, Shu-Shen; Wei, Su-Huai; Luo, Jun-Wei

    2015-11-01

    Group-IV tellurides have exhibited exotic band structures. Specifically, despite the fact that Sn sits between Ge and Pb in the same column of the periodic table, cubic SnTe is a topological crystalline insulator with band inversion, but both isovalent GeTe and PbTe are trivial semiconductors with normal band order. By performing first-principles band structure calculations, we unravel the origin of this abnormal behaviour by using symmetry analysis and the atomic orbital energy levels and atomic sizes of these elements. In group-IV tellurides, the s lone pair band of the group-IV element is allowed by symmetry to couple with the anion valence p band at the L-point, and such s-p coupling leads to the occurrence of bandgap at the L-point. We find that such s-p coupling is so strong in SnTe that it inverts the band order near the bandgap; however, it is not strong enough in both GeTe and PbTe, so they remain normal semiconductors. The reason for this is the incomplete screening of the core of the relatively tight-binding Ge 4s orbital by its 3d orbitals and the large atomic size and strong relativistic effect in Pb, respectively. Interestingly, we also find that the rhombohedral distortion removes the inversion symmetry and the reduced s-p coupling transforms the α-SnTe back to a normal semiconductor. Our study demonstrates that, in addition to spin-orbital coupling, strain and interface dipole fields, inter-orbital coupling is another effective way to engineer the topological insulators.

  19. Influence of Group IV and V Alloying Elements on the Microstructure Engineering and Deformation Behavior in Tantalum Carbides

    DTIC Science & Technology

    2015-04-06

    stable for a range of stoichiometry allowing a large amount of carbon loss. For the group VB compounds, the FCC structure of the metal atoms is...AFRL-OSR-VA-TR-2015-0092 Influence of Group IV and V Alloying Elements on the Microstructure Engineering GREGORY THOMPSON UNIVERSITY OF ALABAMA Final...31/03/2015 4. TITLE AND SUBTITLE Influence of Group IV and V Alloying Elements on the Microstructure Engineering and Deformation Behavior in

  20. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... evaluation criteria for vessels carrying groups I through IV petroleum oil as a primary cargo. 155.1050... through IV petroleum oil as a primary cargo. (a) The following criteria must be used to evaluate the... environment; and (3) Be appropriate for the petroleum oil carried. (d) The owner or operator of a vessel...

  1. Generic process for preparing a crystalline oxide upon a group IV semiconductor substrate

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.; Chisholm, Matthew F.

    2000-01-01

    A process for growing a crystalline oxide epitaxially upon the surface of a Group IV semiconductor, as well as a structure constructed by the process, is described. The semiconductor can be germanium or silicon, and the crystalline oxide can generally be represented by the formula (AO).sub.n (A'BO.sub.3).sub.m in which "n" and "m" are non-negative integer repeats of planes of the alkaline earth oxides or the alkaline earth-containing perovskite oxides. With atomic level control of interfacial thermodynamics in a multicomponent semiconductor/oxide system, a highly perfect interface between a semiconductor and a crystalline oxide can be obtained.

  2. Group-IV nanosheets with vacancies: a tight-binding extended Hückel study

    NASA Astrophysics Data System (ADS)

    de Souza Martins, Adriano; Veríssimo-Alves, Marcos

    2014-09-01

    In this work, we present a theoretical study of the electronic properties of group-IV element nanosheets, namely graphene, silicene, germanene and the corresponding hydrogenated structures for the two latter, silicane and germanane. We compare the results of two different calculation methods, Density Functional Theory (DFT) and Extended Hückel Theory (EHT), for both pristine sheets and sheets of silicene and germanene with a single-atom vacancy. We show that EHT offers a remarkably reliable description of the electronic structure of these materials for all cases, thus offering an affordable way for studying large systems for which DFT calculations would be expensive and lengthy.

  3. Crystal Structures of Human Group-VIIA Phospholipase A2 Inhibited by Organophosphorus Nerve Agents Exhibit Non-aged Complexes ☆,☆☆

    PubMed Central

    Samanta, Uttamkumar; Kirby, Stephen D.; Srinivasan, Prabhavathi; Cerasoli, Douglas M.; Bahnson, Brian J.

    2009-01-01

    The enzyme group-VIIA phospholipase A2 (gVIIA-PLA2) is bound to lipoproteins in human blood and hydrolyzes the ester bond at the sn-2 position of phospholipid substrates with a short sn-2 chain. The enzyme belongs to a serine hydrolase superfamily of enzymes, which react with organophosphorus (OP) nerve agents. OPs ultimately exert their toxicity by inhibiting human acetycholinesterase at nerve synapses, but may additionally have detrimental effects through inhibition of other serine hydrolases. We have solved the crystal structures of gVIIA-PLA2 following inhibition with the OPs diisopropylfluorophosphate, sarin, soman and tabun. The sarin and soman complexes displayed a racemic mix of PR and PS stereoisomers at the P-chiral center. The tabun complex displayed only the PR stereoisomer in the crystal. In all cases, the crystal structures contained intact OP adducts that had not aged. Aging refers to a secondary process OP complexes can go through, which dealkylates the nerve agent adduct and results in a form that is highly resistant to either spontaneous or oxime-mediated reactivation. Non-aged OP complexes of the enzyme were corroborated by trypsin digest and matrix assisted laser desorption ionization mass spectrometry of OP-enzyme complexes. The lack of stereoselectivity of sarin reaction was confirmed by gas chromatography/mass spectrometry using a chiral column to separate and quantitate the unbound stereoisomers of sarin following incubation with enzyme. The structural details and characterization of nascent reactivity of several toxic nerve agents is discussed with a long term goal of developing gVIIA-PLA2 as a catalytic bioscavenger of OP nerve agents. PMID:19394314

  4. ASB14780, an Orally Active Inhibitor of Group IVA Phospholipase A2, Is a Pharmacotherapeutic Candidate for Nonalcoholic Fatty Liver Disease.

    PubMed

    Kanai, Shiho; Ishihara, Keiichi; Kawashita, Eri; Tomoo, Toshiyuki; Nagahira, Kazuhiro; Hayashi, Yasuhiro; Akiba, Satoshi

    2016-03-01

    We have previously shown that high-fat cholesterol diet (HFCD)-induced fatty liver and carbon tetrachloride (CCl4)-induced hepatic fibrosis are reduced in mice deficient in group IVA phospholipase A2 (IVA-PLA2), which plays a role in inflammation. We herein demonstrate the beneficial effects of ASB14780 (3-[1-(4-phenoxyphenyl)-3-(2-phenylethyl)-1H-indol-5-yl]propanoic acid 2-amino-2-(hydroxymethyl)propane-1,3-diol salt), an orally active IVA-PLA2 inhibitor, on the development of fatty liver and hepatic fibrosis in mice. The daily coadministration of ASB14780 markedly ameliorated liver injury and hepatic fibrosis following 6 weeks of treatment with CCl4. ASB14780 markedly attenuated the CCl4-induced expression of smooth muscle α-actin (α-SMA) protein and the mRNA expression of collagen 1a2, α-SMA, and transforming growth factor-β1 in the liver, and inhibited the expression of monocyte/macrophage markers, CD11b and monocyte chemotactic protein-1, while preventing the recruitment of monocytes/macrophages to the liver. Importantly, ASB14780 also reduced the development of fibrosis even in matured hepatic fibrosis. Additionally, ASB14780 also reduced HFCD-induced lipid deposition not only in the liver, but also in already established fatty liver. Furthermore, treatment with ASB14780 suppressed the HFCD-induced expression of lipogenic mRNAs. The present findings suggest that an IVA-PLA2 inhibitor, such as ASB14780, could be useful for the treatment of nonalcoholic fatty liver diseases, including fatty liver and hepatic fibrosis.

  5. Mice with Genetic Deletion of Group VIA Phospholipase A2β Exhibit Impaired Macrophage Function and Increased Parasite Load in Trypanosoma cruzi-Induced Myocarditis

    PubMed Central

    Sharma, Janhavi; Blase, Jennifer R.; Hoft, Daniel F.; Marentette, John O.; Turk, John

    2016-01-01

    Trypanosoma cruzi infection, which is the etiological agent of Chagas disease, is associated with intense inflammation during the acute and chronic phases. The pathological progression of Chagas disease is influenced by the infiltration and transmigration of inflammatory cells across the endothelium to infected tissues, which are carefully regulated processes involving several molecular mediators, including adhesion molecules and platelet-activating factor (PAF). We have shown that PAF production is dependent upon calcium-independent group VIA phospholipase A2β (iPLA2β) following infection of human coronary artery endothelial cells (HCAECs) with T. cruzi, suggesting that the absence of iPLA2β may decrease the recruitment of inflammatory cells to the heart to manage parasite accumulation. Cardiac endothelial cells isolated from iPLA2β-knockout (iPLA2β-KO) mice infected with T. cruzi demonstrated decreased PAF production compared to that by cells isolated from wild-type (WT) mice but demonstrated increases in adhesion molecule expression similar to those seen in WT mice. Myocardial inflammation in iPLA2β-KO mice infected with T. cruzi was similar in severity to that in WT mice, but the iPLA2β-KO mouse myocardium contained more parasite pseudocysts. Upon activation, macrophages from iPLA2β-KO mice produced significantly less nitric oxide (NO) and caused less T. cruzi inhibition than macrophages from wild-type mice. Thus, the absence of iPLA2β activity does not influence myocardial inflammation, but iPLA2β is essential for T. cruzi clearance. PMID:26857573

  6. Optimization of TCR and heat transport in group-IV multiple-quantum-well microbolometers

    NASA Astrophysics Data System (ADS)

    Morea, Matthew; Gu, Kevin; Savikhin, Victoria; Fenrich, Colleen S.; Pop, Eric; Harris, James S.

    2016-09-01

    Group-IV semiconductors have the opportunity to have an equivalent or better temperature coefficient of resistance (TCR) than other microbolometer thermistor materials. By using multiple-quantum-well (MQW) structures, their TCR values can be optimized due to a confinement of carriers. Through two approaches - an activation energy approximation and a custom Monte Carlo transfer matrix method - we simulated this effect for a combination of Group-IV semiconductors and their alloys (e.g., SiGe and GeSn) to find the highest possible TCR, while keeping in mind the critical thicknesses of such layers in a MQW epitaxial stack. We calculated the TCR for a critical-thickness-limited Ge0.8Sn0.2/Ge MQW device to be about -1.9 %/K. Although this TCR is lower than similar SiGe/Si MQW thermistors, GeSn offers possible advantages in terms of fabricating suspended devices with its interesting etch-stop properties shown in previous literature. Furthermore, using finite element modeling of heat transport, we looked at another key bolometer parameter: the thermal time constant. The dimensions of a suspended Ge microbolometer's supporting legs were fine-tuned for a target response time of 5 ms, incorporating estimations for the size effects of the nanowire-like legs on thermal conductivity.

  7. Structural phase stability in group IV metals under static high pressure

    SciTech Connect

    Velisavljevic, Nenad; Chesnut, Garry N; Dattelbaum, Dana M; Vohra, Yogesh K; Stemshorn, Andrew

    2009-01-01

    In group IV metals (Ti, Zr, and Hf) room temperature compression leads to a martensitic transformation from a ductile {alpha} to a brittle {omega} phase. {alpha} {yields} {omega} phase boundary decreases to lower pressure at high temperature and can limit the use of group IV metals in industrial applications. There is a large discrepancy in the transition pressure reported in literature, with some of the variation attributed to experimental conditions (i.e. hydrostatic vs. non-hydrostatic). Shear deformation in non-hydrostatic experiments drives {alpha} {yields} {omega} transition and decreases transition pressure. Impurities can also aid or suppress {alpha} {yields} {omega} transition. By performing x-ray diffraction experiments on samples in a diamond anvil cell we show that interstitial impurities, such as C, N, and O can obstruct {alpha} {yields} {omega} transition and stabilize {alpha} phase to higher pressure. We also show that reduction in grain size can also influence {alpha} {yields} {omega} phase boundary and help stabilize {alpha} phase to higher pressure under non-hydrostatic conditions.

  8. Stability and electronic structure of two-dimensional allotropes of group-IV materials

    NASA Astrophysics Data System (ADS)

    Matusalem, Filipe; Marques, Marcelo; Teles, Lara K.; Bechstedt, Friedhelm

    2015-07-01

    We study six different two-dimensional (2D) allotropes of carbon, silicon, germanium, and tin by means of the ab initio density functional theory for the ground state and approximate methods to calculate their electronic structures, including quasiparticle effects. Four of the investigated allotropes are based on dumbbell geometries, one on a kagome lattice, and one on the graphenelike hexagonal structure for comparison. Concerning carbon, our calculations of the cohesive energies clearly show that the hexagonal structure (graphene) is most stable. However, in the case of Si and Ge, the dumbbell structures, particularly the large honeycomb dumbbell (LHD) geometries, are energetically favored compared to the s p2/s p3 -bonded hexagonal lattice (i.e., silicene and germanene). The main reason for this is the opening of a band gap in the honeycomb dumbbell arrangements. The LHD sheet crystals represent indirect semiconductors with a K →Γ gap of about 0.5 eV. In the Sn case we predict the MoS2-like symmetry to be more stable, in contrast to the stanene and LHD geometries predicted in literature. Our results for freestanding group-IV layers shine new light on recent experimental studies of group-IV overlayers on various substrates.

  9. Growth and applications of GeSn-related group-IV semiconductor materials

    PubMed Central

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-01-01

    We review the technology of Ge1−xSnx-related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1−xSnx-related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1−xSnx-related material thin films and the studies of the electronic properties of thin films, metals/Ge1−xSnx, and insulators/Ge1−xSnx interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1−xSnx-related materials, as well as the reported performances of electronic devices using Ge1−xSnx related materials. PMID:27877818

  10. The development of two dimensional group IV chalcogenides, blocks for van der Waals heterostructures

    NASA Astrophysics Data System (ADS)

    Sa, Baisheng; Sun, Zhimei; Wu, Bo

    2015-12-01

    In this work, we introduce a series of two dimensional (2D) group IV chalcogenides (AX)2 with the building block X-A-A-X (A = Si, Ge, Sn, and Pb, and X = Se and Te) on the basis of ab initio calculations. The analysis of energy evaluation, lattice vibration as well as the chemical bonding demonstrate the good stability of these 2D materials. Furthermore, the pictures for the chemical bonding and electronic features of the 2D (AX)2 are drawn. Their narrow gapped semiconducting nature is unraveled. Especially, strong interactions between the electrons and phonons as well as the topological insulating nature in (SiTe)2 are observed. The present results indicate that such remarkable artificial 2D (AX)2 are building blocks for van der Waals heterostructure engineering, which shows potential applications in nanoscaled electronics and optoelectronics.

  11. Booming Development of Group IV-VI Semiconductors: Fresh Blood of 2D Family.

    PubMed

    Zhou, Xing; Zhang, Qi; Gan, Lin; Li, Huiqiao; Xiong, Jie; Zhai, Tianyou

    2016-12-01

    As an important component of 2D layered materials (2DLMs), the 2D group IV metal chalcogenides (GIVMCs) have drawn much attention recently due to their earth-abundant, low-cost, and environmentally friendly characteristics, thus catering well to the sustainable electronics and optoelectronics applications. In this instructive review, the booming research advancements of 2D GIVMCs in the last few years have been presented. First, the unique crystal and electronic structures are introduced, suggesting novel physical properties. Then the various methods adopted for synthesis of 2D GIVMCs are summarized such as mechanical exfoliation, solvothermal method, and vapor deposition. Furthermore, the review focuses on the applications in field effect transistors and photodetectors based on 2D GIVMCs, and extends to flexible devices. Additionally, the 2D GIVMCs based ternary alloys and heterostructures have also been presented, as well as the applications in electronics and optoelectronics. Finally, the conclusion and outlook have also been presented in the end of the review.

  12. Dimers of heavy p-elements of groups IV-VI: Electronic, vibrational, and magnetic properties

    NASA Astrophysics Data System (ADS)

    Borisova, S. D.; Rusina, G. G.; Eremeev, S. V.; Chulkov, E. V.

    2016-04-01

    Equilibrium lengths and binding energies, vibrational frequencies, width of the HOMO-LUMO gap, and the magnetic anisotropy energies for one- and two-component dimers of heavy p elements of Groups IV (Sn, Pb), V (Sb, Bi), and VI (Se, Te) with a pronounced relativistic effect have been calculated with the use of the formalism of the density functional theory. It has been shown that it is necessary to take into account the spin-orbit coupling, which significantly affects the energy parameters of clusters. The analysis of the data obtained has revealed that the Pb-Te, Pb-Se, Sn-Te, and Sn-Se dimers have the widest gap at the Fermi level and the lowest reactivity. The magnetic anisotropy energy has been calculated for all single- and doublecomponent dimers and the direction of the easy magnetization axis has been determined.

  13. Enhanced piezoelectricity and modified dielectric screening of two-dimensional group-IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Gomes, Lídia C.; Carvalho, A.; Castro Neto, A. H.

    2015-12-01

    We use first-principles calculations to investigate the lattice properties of group-IV monochalcogenides. These include static dielectric permittivity, elastic and piezoelectric tensors. For the monolayer, it is found that the static permittivity, besides acquiring a dependence on the interlayer distance, is comparatively higher than in the 3D system. In contrast, it is found that elastic properties are little changed by the lower dimensionality. Poisson ratios relating in-plane deformations are close to zero, and the existence of a negative Poisson ratio is also predicted for the GeS compound. Finally, the monolayer shows piezoelectricity, with piezoelectric constants higher than those recently predicted to occur in other 2D systems, such as hexagonal BN and transition-metal dichalcogenide monolayers.

  14. Thermoelectric properties of orthorhombic group IV-VI monolayers from the first-principles calculations

    NASA Astrophysics Data System (ADS)

    Guo, San-Dong; Wang, Yue-Hua

    2017-01-01

    Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, the thermoelectric properties of orthorhombic group IV-VI monolayers AB (A = Ge and Sn; B = S and Se) are systematically investigated by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is considered for their electron part, which produces observable effects on the power factor, especially for n-type doping. According to the calculated ZT, the four monolayers exhibit diverse anisotropic thermoelectric properties although they have a similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion. This can be explained by the strength of anisotropy of their respective power factor and electronic and lattice thermal conductivities. The calculated results show that the ZT between n- and p-type doping has little difference for GeS, SnS, and SnSe. It is found that GeSe, SnS, and SnSe show better thermoelectric performance compared to GeS in n-type doping and that SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to other many 2D materials, orthorhombic group IV-VI monolayers AB (A = Ge and Sn; B = S and Se) may possess better thermoelectric performance due to lower lattice thermal conductivities. Our work would be beneficial to stimulate further theoretical and experimental works.

  15. The conflicting role of buckled structure in phonon transport of 2D group-IV and group-V materials.

    PubMed

    Peng, Bo; Zhang, Dequan; Zhang, Hao; Shao, Hezhu; Ni, Gang; Zhu, Yongyuan; Zhu, Heyuan

    2017-03-20

    Controlling heat transport through material design is one important step toward thermal management in 2D materials. To control heat transport, a comprehensive understanding of how structure influences heat transport is required. It has been argued that a buckled structure is able to suppress heat transport by increasing the flexural phonon scattering. Using a first principles approach, we calculate the lattice thermal conductivity of 2D mono-elemental materials with a buckled structure. Somewhat counterintuitively, we find that although 2D group-V materials have a larger mass and higher buckling height than their group-IV counterparts, the calculated κ of blue phosphorene (106.6 W mK(-1)) is nearly four times higher than that of silicene (28.3 W mK(-1)), while arsenene (37.8 W mK(-1)) is more than fifteen times higher than germanene (2.4 W mK(-1)). We report for the first time that a buckled structure has three conflicting effects: (i) increasing the Debye temperature by increasing the overlap of the pz orbitals, (ii) suppressing the acoustic-optical scattering by forming an acoustic-optical gap, and (iii) increasing the flexural phonon scattering. The former two, corresponding to the harmonic phonon part, tend to enhance κ, while the last one, corresponding to the anharmonic part, suppresses it. This relationship between the buckled structure and phonon behaviour provides insight into how to control heat transport in 2D materials.

  16. Two-dimensional group-IV monochalcogenides: structural, electronic and optical properties

    NASA Astrophysics Data System (ADS)

    Gomes, Lidia; Carvalho, Alexandra; Castro Neto, A. H.

    Two-dimensional materials have attracted a massive attention of the scientific and industrial communities due to their unusual and interesting properties. The layered group-IV monochalcogenides-SnS, SnSe, GeS and GeSe- has gained attention as a promising group with potentially useful applications in diverse fields. The bulk SnS, a naturally occurring mineral, has been considered as an alternative to be used in film PV cells, due to its electronic and optical properties. We use first principles calculations to explore structural, electronic and optical properties of this group, with focus in their two-dimensional forms. We show that all those binary compounds are semiconducting, with bandgap energies covering most of the visible range. They have multiple valleys in the valence and conduction bands, with spin-orbit splitting of the order of 19-86 meV. An enhanced static dielectric permittivity is found for the monolayers. Structural analysis shows that the 2D form of these materials presents very high piezoelectric constants, exceeding values recently observed for other 2D-systems. The existence of a negative Poisson ratio is predicted for the GeS compound. We acknowledge the NRF-CRP award ``Novel 2D materials with tailored properties: beyond graphene'' (R-144-000-295-281).

  17. Covalently-controlled properties by design in group IV graphane analogues.

    PubMed

    Jiang, Shishi; Arguilla, Maxx Q; Cultrara, Nicholas D; Goldberger, Joshua E

    2015-01-20

    CONSPECTUS: The isolation of graphene has sparked a renaissance in the study of two-dimensional materials. This led to the discovery of new and unique phenomena such as extremely high carrier mobility, thermal conductivity, and mechanical strength not observed in the parent 3D structure. While the emergence of these phenomena has spurred widespread interest in graphene, the paradox between the high-mobility Fermi-Dirac electronic structure and the need for a sizable band gap has challenged its application in traditional semiconductor devices. While graphene is a fascinating and promising material, the limitation of its electronic structure has inspired researchers to explore other 2D materials beyond graphene. In this Account, we summarize our recent work on a new family of two-dimensional materials based on sp(3)-hybridized group IV elements. Ligand-terminated Si, Ge, and Sn graphane analogues are an emerging and unique class of two-dimensional materials that offer the potential to tailor the structure, stability, and properties. Compared with bulk Si and Ge, a direct and larger band gap is apparent in group IV graphane analogues depending on the surface ligand. These materials can be synthesized in gram-scale quantities and in thin films via the topotactic deintercalation of layered Zintl phase precursors. Few layers and single layers can be isolated via manual exfoliation and deintercalation of epitaxially grown Zintl phases on Si/Ge substrates. The presence of a fourth bond on the surface of the layers allows various surface ligand termination with different organic functional groups achieved via conventional soft chemical routes. In these single-atom thick materials, the electronic structure can be systematically controlled by varying the identities of the main group elements and by attaching different surface terminating ligands. In contrast to transition metal dichalcogenides, the weaker interlayer interaction allows the direct band gap single layer

  18. Validation of Nuclear Criticality Safety Software and 27 energy group ENDF/B-IV cross sections

    SciTech Connect

    Lee, B.L. Jr.

    1994-08-01

    The validation documented in this report is based on calculations that were executed during June through August 1992, and was completed in June 1993. The statistical analyses in Appendix C and Appendix D were completed in October 1993. This validation gives Portsmouth NCS personnel a basis for performing computerized KENO V.a calculations using the Martin Marietta Nuclear Criticality Safety Software. The first portion of the document outlines basic information in regard to validation of NCSS using ENDF/B-IV 27-group cross sections on the IBM 3090 at ORNL. A basic discussion of the NCSS system is provided, some discussion on the validation database and validation in general. Then follows a detailed description of the statistical analysis which was applied. The results of this validation indicate that the NCSS software may be used with confidence for criticality calculations at the Portsmouth Gaseous Diffusion Plant. When the validation results are treated as a single group, there is 95% confidence that 99.9% of future calculations of similar critical systems will have a calculated K{sub eff} > 0.9616. Based on this result the Portsmouth Nuclear Criticality Safety Department has adopted the calculational acceptance criteria that a k{sub eff} + 2{sigma} {le} 0.95 is safety subcritical. The validation of NCSS on the IBM 3090 at ORNL was extended to include NCSS on the IBM 3090 at K-25.

  19. Bacterial Sphingomyelinases and Phospholipases as Virulence Factors.

    PubMed

    Flores-Díaz, Marietta; Monturiol-Gross, Laura; Naylor, Claire; Alape-Girón, Alberto; Flieger, Antje

    2016-09-01

    Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural aspects. An overview of the main physiopathological activities is provided for each enzyme type, as are examples in which inactivation of a sphingomyelinase- or a phospholipase-encoding gene impairs the virulence of a pathogen. The identification of sphingomyelinases and phospholipases important for bacterial pathogenesis and the development of inhibitors for these enzymes could generate candidate vaccines and therapeutic agents, which will diminish the impacts of the associated human and animal diseases.

  20. Introduction of bifunctional groups into mesoporous silica for enhancing uptake of thorium(IV) from aqueous solution.

    PubMed

    Yuan, Li-Yong; Bai, Zhi-Qiang; Zhao, Ran; Liu, Ya-Lan; Li, Zi-Jie; Chu, Sheng-Qi; Zheng, Li-Rong; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-04-09

    The potential industrial application of thorium (Th), as well as the environmental and human healthy problems caused by thorium, promotes the development of reliable methods for the separation and removal of Th(IV) from environmental and geological samples. Herein, the phosphonate-amino bifunctionalized mesoporous silica (PAMS) was fabricated by a one-step self-assembly approach for enhancing Th(IV) uptake from aqueous solution. The synthesized sorbent was found to possess ordered mesoporous structures with uniform pore diameter and large surface area, characterized by SEM, XRD, and N2 sorption/desorption measurements. The enhancement of Th(IV) uptake by PAMS was achieved by coupling of an access mechanism to a complexation mechanism, and the sorption can be optimized by adjusting the coverage of the functional groups in the PAMS sorbent. The systemic study on Th(IV) sorption/desorption by using one coverage of PAMS (PAMS12) shows that the Th(IV) sorption by PAMS is fast with equilibrium time of less than 1 h, and the sorption capacity is more than 160 mg/g at a relatively low pH. The sorption isotherm has been successfully modeled by the Langmuir isotherm and D-R isotherm, which reveals a monolayer homogeneous chemisorption of Th(IV) in PAMS. The Th(IV) sorption by PAMS is pH dependent but ionic strength independent. In addition, the sorbed Th(IV) can be completely desorbed using 0.2 mol/L or more concentrated nitric acid solution. The sorption test performed in the solution containing a range of competing metal ions suggests that the PAMS sorbent has a desirable selectivity for Th(IV) ions.

  1. The Ultraviolet Photoelectron Spectroscopy of Group IV 2-15 Atom Cluster Anions

    NASA Astrophysics Data System (ADS)

    Craycraft, Mary Jo.

    The ability to map valence electronic structure is the result of a recent advance in photoelectron spectroscopy; its union with cluster molecular beam technology. The task of interpreting the spectra is hampered by a serious lack of understanding of cluster electronic structure in general. Recently progress has been made in finding models for single s valence electron systems. Alkali and noble metal clusters can be treated as free electron systems and simple interatomic potentials can be used with rare gas clusters. Neither a smeared jellium background nor a simple interatomic potential is adequate to describe covalent bonding, however. The isoelectronic Group IV members have a valence configuration of ns^2 np^2. All readily form clusters, and the elements differ in both their atomic and bulk properties; thus the series provides an ideal system for studying electronic structure. The mass selected cluster ion beam is crossed with a beam (6.42 or 7.9eV) and the resulting photodetached electrons collected with the aid of judiciously arranged magnetic fields. The spectra are found to be unique for each size cluster. Some spectra show a significant gap between the two lowest binding energy features, indicating that the neutral cluster is a closed shell species. The clusters with such gaps are minima in a plot of EA as a function of cluster size. The UPS also vary with the cluster composition. Carbon is unique; an even -odd alternation in electron affinities switches from odd minima for clusters containing less than ten atoms to odd maxima for larger clusters. This corresponds with an alternation in singlet and triplet ground states and a switch from chain to ring structures previously predicted by theory (K. S. Pitzer, E. Clementi, J. Amer. Chem. Soc. 81 4477 (1958) and R. Hoffmann, Tetrahedron 22 521 (1965)). The spectra of the remaining group IV members are remarkably similar to each other for clusters of up to ten atoms, as is the trend in the electron affinities as

  2. Hybrid Group IV Nanophotonic Structures Incorporating Diamond Silicon-Vacancy Color Centers

    NASA Astrophysics Data System (ADS)

    Zhang, Jingyuan Linda; Ishiwata, Hitoshi; Babinec, Thomas M.; Radulaski, Marina; Müller, Kai; Lagoudakis, Konstantinos G.; Dory, Constantin; Dahl, Jeremy; Edgington, Robert; Soulière, Veronique; Ferro, Gabriel; Fokin, Andrey A.; Schreiner, Peter R.; Shen, Zhi-Xun; Melosh, Nicholas A.; Vučković, Jelena

    2016-01-01

    We demonstrate a new approach for engineering group IV semiconductor-based quantum photonic structures containing negatively charged silicon-vacancy (SiV$^-$) color centers in diamond as quantum emitters. Hybrid SiC/diamond structures are realized by combining the growth of nanoand micro-diamonds on silicon carbide (3C or 4H polytype) substrates, with the subsequent use of these diamond crystals as a hard mask for pattern transfer. SiV$^-$ color centers are incorporated in diamond during its synthesis from molecular diamond seeds (diamondoids), with no need for ionimplantation or annealing. We show that the same growth technique can be used to grow a diamond layer controllably doped with SiV$^-$ on top of a high purity bulk diamond, in which we subsequently fabricate nanopillar arrays containing high quality SiV$^-$ centers. Scanning confocal photoluminescence measurements reveal optically active SiV$^-$ lines both at room temperature and low temperature (5 K) from all fabricated structures, and, in particular, very narrow linewidths and small inhomogeneous broadening of SiV$^-$ lines from all-diamond nano-pillar arrays, which is a critical requirement for quantum computation. At low temperatures (5 K) we observe in these structures the signature typical of SiV$^-$ centers in bulk diamond, consistent with a double lambda. These results indicate that high quality color centers can be incorporated into nanophotonic structures synthetically with properties equivalent to those in bulk diamond, thereby opening opportunities for applications in classical and quantum information processing.

  3. Modeling Group IV elements with new transferable tight-binding models

    SciTech Connect

    Kwon, I.; Biswas, R.

    1993-10-01

    An outstanding problem in the computer-based microscopic description of Group IV materials, is the need for an accurate transferable model of the energetic and electronic properties of semiconductor structures. The three complementary approaches have been the ab-initio method including Car-Parinello simulations, the classical molecular dynamics method, and tight-binding molecular dynamics. While being very accurate, the ab-initio molecular dynamics has been performed on small systems ({approximately}100 atoms) for short time scales ({approximately}10 ps). On the other hand, classical potential models have had much success in describing melting of silicon, amorphous silicon structures, thin film growth and a variety of computationally intensive molecular dynamics simulations. However, the classical based models do not contain important electronic information which is essential in a variety of problems in electronic materials such as determining the gap states for structural defects. The accuracy of the classical models in configurations, far from the fitting database, may be uncertain. Our approach is to find transferable tight-binding models for silicon that are in between the ab-initio simulations and the classical models for molecular dynamics in level of sophistication.

  4. Full first-principles theory of spin relaxation in group-IV materials.

    PubMed

    Restrepo, O D; Windl, W

    2012-10-19

    We present a generally applicable parameter-free first-principles method to determine electronic spin relaxation times and apply it to the technologically important group-IV materials silicon, diamond, and graphite. We concentrate on the Elliott-Yafet mechanism, where spin relaxation is induced by momentum scattering off phonons and impurities. In silicon, we find a ~T(-3) temperature dependence of the phonon-limited spin relaxation time T(1) and a value of 4.3 ns at room temperature, in agreement with experiments. For the phonon-dominated regime in diamond and graphite, we predict a stronger ~T(-5) and ~T(-4.5) dependence that limits T(1) (300 K) to 180 and 5.8 ns, respectively. A key aspect of this Letter is that the parameter-free nature of our approach provides a method to study the effect of any type of impurity or defect on spin transport. Furthermore we find that the spin-mix amplitude in silicon does not follow the E(g)(-2) band gap dependence usually assigned to III-V semiconductors but follows a much weaker and opposite E(g)(0.67) dependence. This dependence should be taken into account when constructing silicon spin transport models.

  5. Full First-Principles Theory of Spin Relaxation in Group-IV Materials

    NASA Astrophysics Data System (ADS)

    Restrepo, O. D.; Windl, W.

    2012-10-01

    We present a generally applicable parameter-free first-principles method to determine electronic spin relaxation times and apply it to the technologically important group-IV materials silicon, diamond, and graphite. We concentrate on the Elliott-Yafet mechanism, where spin relaxation is induced by momentum scattering off phonons and impurities. In silicon, we find a ˜T-3 temperature dependence of the phonon-limited spin relaxation time T1 and a value of 4.3 ns at room temperature, in agreement with experiments. For the phonon-dominated regime in diamond and graphite, we predict a stronger ˜T-5 and ˜T-4.5 dependence that limits T1 (300 K) to 180 and 5.8 ns, respectively. A key aspect of this Letter is that the parameter-free nature of our approach provides a method to study the effect of any type of impurity or defect on spin transport. Furthermore we find that the spin-mix amplitude in silicon does not follow the Eg-2 band gap dependence usually assigned to III-V semiconductors but follows a much weaker and opposite Eg0.67 dependence. This dependence should be taken into account when constructing silicon spin transport models.

  6. Photoelectron Spectroscopy and Electronic Structure of Heavy GroupIV-VI Diatomics

    SciTech Connect

    Wang, L.-S.; Niu, B.; Lee, Yuan T.; Shirley, D.A.; Balasubramanian, K.

    1989-09-01

    Vibrationally-resolved HeI (584{angstrom}) photoelectron spectra of the heavy group IV-VI diatomics SnSe, SnTe, PbSe, and PbTe were obtained with a new high temperature molecular beam source. Ionization potentials and spectroscopic constants are reported for all the ionic states observed. Relativistic complete active space MCSCF followed by multireference singles + doubles relativistic CI calculations which included up to 200,000 configurations were made on both the neutral diatomics and their positive ions. Ionization potentials and spectroscopic constants were calculated and were in good agreement with the experimentally-measured values. Relativistic CI potential energy curves were calculated for all the neutral ground states and the ionic states involved. Relativistic effects were shown to play an important role in these heavy diatomics. The {sup 2}{Sigma}{sub 1/2}{sup +} and {sup 2}{Pi}{sub 1/2} states for all four molecular ions showed avoided curve crossings, which resulted in pronounced shoulders in the {Omega} = 1/2 potential energy curves of PbTe{sup +}. Experimentally, autoionization transitions were also observed for the PbTe{sup +} spectrum. The importance of the relativistic effect and chemical bonding in the heavy diatomics are discussed.

  7. Tunable magnetic states on the zigzag edges of hydrogenated and halogenated group-IV nanoribbons

    NASA Astrophysics Data System (ADS)

    Wang, Tzu-Cheng; Hsu, Chia-Hsiu; Huang, Zhi-Quan; Chuang, Feng-Chuan; Su, Wan-Sheng; Guo, Guang-Yu

    2016-12-01

    The magnetic and electronic properties of hydrogenated and halogenated group-IV zigzag nanoribbons (ZNRs) are investigated by first-principles density functional calculations. Fascinatingly, we find that all the ZNRs have magnetic edges with a rich variety of electronic and magnetic properties tunable by selecting the parent and passivating elements as well as controlling the magnetization direction and external strain. In particular, the electric property of the edge band structure can be tuned from the conducting to insulating with a band gap up to 0.7 eV. The last controllability would allow us to develop magnetic on-off nano-switches. Furthermore, ZNRs such as SiI, Ge, GeI and SnH, have fully spin-polarized metallic edge states and thus are promising materials for spintronics. The calculated magnetocrystalline anisotropy energy can be as large as ~9 meV/edge-site, being 2×103 time greater than that of bulk Ni and Fe (~5 μeV/atom), and thus has great potential for high density magneto-electric data-storage devices. Finally, the calculated exchange coupling strength and thus magnetic transition temperature increases as the applied strain goes from ‑5% to 5%. Our findings thus show that these ZNRs would have exciting applications in next-generation electronic and spintronic nano-devices.

  8. Tunable magnetic states on the zigzag edges of hydrogenated and halogenated group-IV nanoribbons

    PubMed Central

    Wang, Tzu-Cheng; Hsu, Chia-Hsiu; Huang, Zhi-Quan; Chuang, Feng-Chuan; Su, Wan-Sheng; Guo, Guang-Yu

    2016-01-01

    The magnetic and electronic properties of hydrogenated and halogenated group-IV zigzag nanoribbons (ZNRs) are investigated by first-principles density functional calculations. Fascinatingly, we find that all the ZNRs have magnetic edges with a rich variety of electronic and magnetic properties tunable by selecting the parent and passivating elements as well as controlling the magnetization direction and external strain. In particular, the electric property of the edge band structure can be tuned from the conducting to insulating with a band gap up to 0.7 eV. The last controllability would allow us to develop magnetic on-off nano-switches. Furthermore, ZNRs such as SiI, Ge, GeI and SnH, have fully spin-polarized metallic edge states and thus are promising materials for spintronics. The calculated magnetocrystalline anisotropy energy can be as large as ~9 meV/edge-site, being 2×103 time greater than that of bulk Ni and Fe (~5 μeV/atom), and thus has great potential for high density magneto-electric data-storage devices. Finally, the calculated exchange coupling strength and thus magnetic transition temperature increases as the applied strain goes from −5% to 5%. Our findings thus show that these ZNRs would have exciting applications in next-generation electronic and spintronic nano-devices. PMID:27982055

  9. Structure and magnetism in novel group IV element-based magnetic materials

    SciTech Connect

    Tsui, Frank

    2013-08-14

    The project is to investigate structure, magnetism and spin dependent states of novel group IV element-based magnetic thin films and heterostructures as a function of composition and epitaxial constraints. The materials systems of interest are Si-compatible epitaxial films and heterostructures of Si/Ge-based magnetic ternary alloys grown by non-equilibrium molecular beam epitaxy (MBE) techniques, specifically doped magnetic semiconductors (DMS) and half-metallic Heusler alloys. Systematic structural, chemical, magnetic, and electrical measurements are carried out, using x-ray microbeam techniques, magnetotunneling spectroscopy and microscopy, and magnetotransport. The work is aimed at elucidating the nature and interplay between structure, chemical order, magnetism, and spin-dependent states in these novel materials, at developing materials and techniques to realize and control fully spin polarized states, and at exploring fundamental processes that stabilize the epitaxial magnetic nanostructures and control the electronic and magnetic states in these complex materials. Combinatorial approach provides the means for the systematic studies, and the complex nature of the work necessitates this approach.

  10. Phonon transport properties of two-dimensional group-IV materials from ab initio calculations

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuanfeng; Ni, Gang; Zhang, Rongjun; Zhu, Heyuan

    2016-12-01

    It has been argued that stanene has lowest lattice thermal conductivity among two-dimensional (2D) group-IV materials because of its largest atomic mass, weakest interatomic bonding, and enhanced ZA phonon scattering due to the breaking of an out-of-plane symmetry selection rule. However, we show that, although the lattice thermal conductivity κ for graphene, silicene, and germanene decreases monotonically with decreasing Debye temperature, unexpected higher κ is observed in stanene. By enforcing all the invariance conditions in 2D materials and including Ge 3 d and Sn 4 d electrons as valence electrons for germanene and stanene, respectively, the lattice dynamics in these materials are accurately described. A large acoustic-optical gap and the bunching of the acoustic-phonon branches significantly reduce phonon scattering in stanene, leading to higher thermal conductivity than germanene. The vibrational origin of the acoustic-optical gap can be attributed to the buckled structure. Interestingly, a buckled system has two competing influences on phonon transport: the breaking of the symmetry selection rule leads to reduced thermal conductivity, and the enlarging of the acoustic-optical gap results in enhanced thermal conductivity. The size dependence of thermal conductivity is investigated as well. In nanoribbons, the κ of silicene, germanene, and stanene is much less sensitive to size effect due to their short intrinsic phonon mean-free paths. This work sheds light on the nature of phonon transport in buckled 2D materials.

  11. Expression of ABH blood group antigens, Ulex europaeus agglutinin I, and type IV collagen in the sinusoids of hepatocellular carcinoma.

    PubMed

    Terada, T; Nakanuma, Y

    1991-01-01

    The expression of blood group antigens (A, B, H, Lewis(a) and Lewis(b)), Ulex europaeus agglutinin I (UEA-I), factor VIII-related antigen, and type IV collagen on the sinusoids was examined immunohistochemically in 15 cases of hepatocellular carcinomas (HCC), 11 cases of cirrhosis, 12 cases of chronic active hepatitis, and in a control sample of 16 normal livers. Sinusoidal endothelial cells of HCC characteristically showed a diffuse and strong immunoreactivity to ABH blood group antigens in the specimen with a comparable ABO blood group. The sinusoidal endothelial cells were also diffusely and strongly positive for UEA-I receptors. In contrast, in cirrhosis and chronic active hepatitis a few sinusoidal endothelial cells were positive for ABH blood group antigens and UEA-I receptors. In normal livers, only a few sinusoidal endothelial cells were positive for ABH blood group antigens and UEA-1 receptors. Tests for factor VIII-related antigen and Lewis blood group antigens were almost negative on sinusoidal endothelial cells. Although type IV collagen was distributed diffusely in the space of Disse in these four groups, its expression was strongest in HCC. Blood vessels of portal tracts and fibrous septa were positive for ABH blood group antigens, UEA-1 receptors, factor VIII-related antigen, and type IV collagen, but negative for Lewis blood group antigens. These findings suggest that some sinusoidal endothelial cells undergo "capillarization" in cirrhosis and chronic active hepatitis, and that the majority of sinusoidal endothelial cells of HCC have phenotypic characteristics of capillaries.

  12. Mast cell maturation is driven via a group III phospholipase A2-prostaglandin D2–DP1 receptor paracrine axis

    PubMed Central

    Taketomi, Yoshitaka; Ueno, Noriko; Kojima, Takumi; Sato, Hiroyasu; Murase, Remi; Yamamoto, Kei; Tanaka, Satoshi; Sakanaka, Mariko; Nakamura, Masanori; Nishito, Yasumasa; Kawana, Momoko; Kambe, Naotomo; Ikeda, Kazutaka; Taguchi, Ryo; Nakamizo, Satoshi; Kabashima, Kenji; Gelb, Michael H.; Arita, Makoto; Yokomizo, Takehiko; Nakamura, Motonao; Watanabe, Kikuko; Hirai, Hiroyuki; Nakamura, Masataka; Okayama, Yoshimichi; Ra, Chisei; Aritake, Kosuke; Urade, Yoshihiro; Morimoto, Kazushi; Sugimoto, Yukihiko; Shimizu, Takao; Narumiya, Shuh; Hara, Shuntaro; Murakami, Makoto

    2014-01-01

    Microenvironment-based alterations in phenotypes of mast cells influence the susceptibility to anaphylaxis, yet the mechanisms underlying proper maturation of mast cells toward an anaphylaxis-sensitive phenotype are incompletely understood. Here we report that PLA2G3, a mammalian homolog of anaphylactic bee venom phospholipase A2, regulates this process. PLA2G3 secreted from mast cells is coupled with fibroblastic lipocalin-type PGD2 synthase (L-PGDS) to provide PGD2, which facilitates mast-cell maturation via PGD2 receptor DP1. Mice lacking PLA2G3, L-PGDS or DP1, mast cell–deficient mice reconstituted with PLA2G3-null or DP1-null mast cells, or mast cells cultured with L-PGDS–ablated fibroblasts exhibited impaired maturation and anaphylaxis of mast cells. Thus, we describe a lipid-driven PLA2G3–L-PGDS–DP1 loop that drives mast cell maturation. PMID:23624557

  13. A new group in the Leptospirillum clade: cultivation-independent community genomics, proteomics and transcriptomics of the new species Leptospirillum group IV UBA BS.

    SciTech Connect

    Goltsman, Daniela; Dasari, Mauna; Thomas, BC; Shah, Manesh B; Verberkmoes, Nathan C; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2013-01-01

    Leptospirillum spp. are widespread members of acidophilic microbial communities that catalyze ferrous iron oxidation, thereby increasing sulfide mineral dissolution rates. These bacteria play important roles in environmental acidification and are harnessed for bioleaching-based metal recovery. Known members of the Leptospirillum clade of the Nitrospira phylum are Leptospirillum ferrooxidans (group I), Leptospirillum ferriphilum and Leptospirillum rubarum (group II), and Leptospirillum ferrodiazotrophum (group III). In the Richmond Mine acid mine drainage (AMD) system, biofilm formation is initiated by L. rubarum; L. ferrodiazotrophum appears in later developmental stages. Here we used community metagenomic data from unusual, thick floating biofilms to identify distinguishing metabolic traits in a rare and uncultivated community member, the new species Leptospirillum group IV UBA BS. These biofilms typically also contain a variety of Archaea, Actinobacteria, and a few other Leptospirillum spp. The Leptospirillum group IV UBA BS species shares 98% 16S rRNA sequence identity and 70% average amino acid identity between orthologs with its closest relative, L. ferrodiazotrophum. The presence of nitrogen fixation and reverse tricarboxylic acid (TCA) cycle proteins suggest an autotrophic metabolism similar to that of L. ferrodiazotrophum, while hydrogenase proteins suggest anaerobic metabolism. Community transcriptomic and proteomic analyses demonstrate expression of a multicopper oxidase unique to this species, as well as hydrogenases and core metabolic genes. Results suggest that the Leptospirillum group IV UBA BS species might play important roles in carbon fixation, nitrogen fixation, hydrogen metabolism, and iron oxidation in some acidic environments.

  14. Cytosolic phospholipase A2: physiological function and role in disease

    PubMed Central

    Leslie, Christina C.

    2015-01-01

    The group IV phospholipase A2 (PLA2) family is comprised of six intracellular enzymes (GIVA, -B, -C, -D, -E, and -F) commonly referred to as cytosolic PLA2 (cPLA2)α, -β, -γ, -δ, -ε, and -ζ. They contain a Ser-Asp catalytic dyad and all except cPLA2γ have a C2 domain, but differences in their catalytic activities and subcellular localization suggest unique regulation and function. With the exception of cPLA2α, the focus of this review, little is known about the in vivo function of group IV enzymes. cPLA2α catalyzes the hydrolysis of phospholipids to arachidonic acid and lysophospholipids that are precursors of numerous bioactive lipids. The regulation of cPLA2α is complex, involving transcriptional and posttranslational processes, particularly increases in calcium and phosphorylation. cPLA2α is a highly conserved widely expressed enzyme that promotes lipid mediator production in human and rodent cells from a variety of tissues. The diverse bioactive lipids produced as a result of cPLA2α activation regulate normal physiological processes and disease pathogenesis in many organ systems, as shown using cPLA2α KO mice. However, humans recently identified with cPLA2α deficiency exhibit more pronounced effects on health than observed in mice lacking cPLA2α, indicating that much remains to be learned about this interesting enzyme. PMID:25838312

  15. Cytosolic phospholipase A₂: physiological function and role in disease.

    PubMed

    Leslie, Christina C

    2015-08-01

    The group IV phospholipase A2 (PLA2) family is comprised of six intracellular enzymes (GIVA, -B, -C, -D, -E, and -F) commonly referred to as cytosolic PLA2 (cPLA2)α, -β, -γ, -δ, -ε, and -ζ. They contain a Ser-Asp catalytic dyad and all except cPLA2γ have a C2 domain, but differences in their catalytic activities and subcellular localization suggest unique regulation and function. With the exception of cPLA2α, the focus of this review, little is known about the in vivo function of group IV enzymes. cPLA2α catalyzes the hydrolysis of phospholipids to arachidonic acid and lysophospholipids that are precursors of numerous bioactive lipids. The regulation of cPLA2α is complex, involving transcriptional and posttranslational processes, particularly increases in calcium and phosphorylation. cPLA2α is a highly conserved widely expressed enzyme that promotes lipid mediator production in human and rodent cells from a variety of tissues. The diverse bioactive lipids produced as a result of cPLA2α activation regulate normal physiological processes and disease pathogenesis in many organ systems, as shown using cPLA2α KO mice. However, humans recently identified with cPLA2α deficiency exhibit more pronounced effects on health than observed in mice lacking cPLA2α, indicating that much remains to be learned about this interesting enzyme.

  16. Structure-activity relationship studies on 1-heteroaryl-3-phenoxypropan-2-ones acting as inhibitors of cytosolic phospholipase A2α and fatty acid amide hydrolase: replacement of the activated ketone group by other serine traps.

    PubMed

    Sundermann, Tom; Hanekamp, Walburga; Lehr, Matthias

    2016-08-01

    Cytosolic phospholipase A2α (cPLA2α) and fatty acid amide hydrolase (FAAH) are serine hydrolases. cPLA2α is involved in the generation of pro-inflammatory lipid mediators, FAAH terminates the anti-inflammatory effects of endocannabinoids. Therefore, inhibitors of these enzymes may represent new drug candidates for the treatment of inflammation. We have reported that certain 1-heteroarylpropan-2-ones are potent inhibitors of cPLA2α and FAAH. The serine reactive ketone group of these compounds, which is crucial for enzyme inhibition, is readily metabolized resulting in inactive alcohol derivatives. In order to obtain metabolically more stable inhibitors, we replaced this moiety by α-ketoheterocyle, cyanamide and nitrile serine traps. Investigations on activity and metabolic stability of these substances revealed that in all cases an increased metabolic stability was accompanied by a loss of inhibitory potency against cPLA2α and FAAH, respectively.

  17. Group III/IV locomotor muscle afferents alter motor cortical and corticospinal excitability and promote central fatigue during cycling exercise

    PubMed Central

    Sidhu, Simranjit K.; Weavil, Joshua C.; Mangum, Tyler S.; Jessop, Jacob E.; Richardson, Russell S.; Morgan, David E.; Amann, Markus

    2017-01-01

    Objective To investigate the influence of group III/IV muscle afferents on the development of central fatigue and corticospinal excitability during exercise. Methods Fourteen males performed cycling-exercise both under control-conditions (CTRL) and with lumbar intrathecal fentanyl (FENT) impairing feedback from leg muscle afferents. Transcranial magnetic- and cervicomedullary stimulation was used to monitor cortical versus spinal excitability. Results While fentanyl-blockade during non-fatiguing cycling had no effect on motor-evoked potentials (MEPs), cervicomedullary-evoked motor potentials (CMEPs) were 13 ± 3% higher (P < 0.05), resulting in a decrease in MEP/CMEP (P < 0.05). Although the pre- to post-exercise reduction in resting twitch was greater in FENT vs. CTRL (−53 ± 3% vs. −39 ± 3%; P < 0.01), the reduction in voluntary muscle activation was smaller (−2 ± 2% vs. −10 ± 2%; P < 0.05). Compared to the start of fatiguing exercise, MEPs and CMEPs were unchanged at exhaustion in CTRL. In contrast, MEPs and MEP/CMEP increased 13 ± 3% and 25 ± 6% in FENT (P < 0.05). Conclusion During non-fatiguing exercise, group III/IV muscle afferents disfacilitate, or inhibit, spinal motoneurons and facilitate motor cortical cells. In contrast, during exhaustive exercise, group III/IV muscle afferents disfacilitate/inhibit the motor cortex and promote central fatigue. Significance Group III/IV muscle afferents influence corticospinal excitability and central fatigue during whole-body exercise in humans. PMID:27866119

  18. Development of group IV molecular catalysts for high temperature ethylene-α-olefin copolymerization reactions.

    PubMed

    Klosin, Jerzy; Fontaine, Philip P; Figueroa, Ruth

    2015-07-21

    This Account describes our research related to the development of molecular catalysts for solution phase olefin polymerization. Specifically, a series of constrained geometry and nonmetallocene (imino-amido-type) complexes were developed for high temperature olefin polymerization reactions. We have discovered many highly active catalysts that are capable of operating at temperatures above 120 °C and producing copolymers with a useful range of molecular weights (from medium to ultrahigh depending on precatalyst identity and polymerization conditions) and α-olefin incorporation capability. Constrained geometry catalysts (CGCs) exhibit very high activities and are capable of producing a variety of copolymers including ethylene-propylene and ethylene-1-octene copolymers at high reactor temperatures. Importantly, CGCs have much higher reactivity toward α-olefins than classical Ziegler-Natta catalysts, thus allowing for the production of copolymers with any desired level of comonomer. In search of catalysts with improved performance, we discovered 3-amino-substituted indenyl-based CGCs that exhibit the highest activity and produce copolymers with the highest molecular weight within this family of catalysts. Phenanthrenyl-based CGCs were found to be outstanding catalysts for the effective production of high styrene content ethylene-styrene copolymers under industrially relevant conditions. In contrast to CGC ligands, imino-amido-type ligands are bidentate and monoionic, leading to the use of trialkyl group IV precatalysts. The thermal instability of imino-amido complexes was addressed by the development of imino-enamido and amidoquinoline complexes, which are not only thermally very robust, but also produce copolymers with higher molecular weights, and exhibit improved α-olefin incorporation. Imido-amido and imino-enamido catalysts undergo facile chain transfer reactions with metal alkyls, as evidenced by a sharp decrease in polymer molecular weight when the

  19. Myeloperoxidase and serum amyloid A contribute to impaired in vivo reverse cholesterol transport during the acute phase response but not group IIA secretory phospholipase A2[S

    PubMed Central

    Annema, Wijtske; Nijstad, Niels; Tölle, Markus; de Boer, Jan Freark; Buijs, Ruben V. C.; Heeringa, Peter; van der Giet, Markus; Tietge, Uwe J. F.

    2010-01-01

    Atherosclerosis is linked to inflammation. HDL protects against atherosclerotic cardiovascular disease, mainly by mediating cholesterol efflux and reverse cholesterol transport (RCT). The present study aimed to test the impact of acute inflammation as well as selected acute phase proteins on RCT with a macrophage-to-feces in vivo RCT assay using intraperitoneal administration of [3H]cholesterol-labeled macrophage foam cells. In patients with acute sepsis, cholesterol efflux toward plasma and HDL were significantly decreased (P < 0.001). In mice, acute inflammation (75 µg/mouse lipopolysaccharide) decreased [3H]cholesterol appearance in plasma (P < 0.05) and tracer excretion into feces both within bile acids (−84%) and neutral sterols (−79%, each P < 0.001). In the absence of systemic inflammation, overexpression of serum amyloid A (SAA, adenovirus) reduced overall RCT (P < 0.05), whereas secretory phospholipase A2 (sPLA2, transgenic mice) had no effect. Myeloperoxidase injection reduced tracer appearance in plasma (P < 0.05) as well as RCT (−36%, P < 0.05). Hepatic expression of bile acid synthesis genes (P < 0.01) and transporters mediating biliary sterol excretion (P < 0.01) was decreased by inflammation. In conclusion, our data demonstrate that acute inflammation impairs cholesterol efflux in patients and macrophage-to-feces RCT in vivo in mice. Myeloperoxidase and SAA contribute to a certain extent to reduced RCT during inflammation but not sPLA2. However, reduced bile acid formation and decreased biliary sterol excretion might represent major contributing factors to decreased RCT in inflammation. PMID:20061576

  20. AMPK Signaling Involvement for the Repression of the IL-1β-Induced Group IIA Secretory Phospholipase A2 Expression in VSMCs

    PubMed Central

    El Hadri, Khadija; Denoyelle, Chantal; Ravaux, Lucas; Viollet, Benoit; Foretz, Marc; Friguet, Bertrand; Rouis, Mustapha; Raymondjean, Michel

    2015-01-01

    Secretory Phospholipase A2 of type IIA (sPLA2 IIA) plays a crucial role in the production of lipid mediators by amplifying the neointimal inflammatory context of the vascular smooth muscle cells (VSMCs), especially during atherogenesis. Phenformin, a biguanide family member, by its anti-inflammatory properties presents potential for promoting beneficial effects upon vascular cells, however its impact upon the IL-1β-induced sPLA2 gene expression has not been deeply investigated so far. The present study was designed to determine the relationship between phenformin coupling AMP-activated protein kinase (AMPK) function and the molecular mechanism by which the sPLA2 IIA expression was modulated in VSMCs. Here we find that 5-aminoimidazole-4-carboxamide-1-β-D-ribonucleotide (AICAR) treatment strongly repressed IL-1β-induced sPLA2 expression at least at the transcriptional level. Our study reveals that phenformin elicited a dose-dependent inhibition of the sPLA2 IIA expression and transient overexpression experiments of constitutively active AMPK demonstrate clearly that AMPK signaling is involved in the transcriptional inhibition of sPLA2-IIA gene expression. Furthermore, although the expression of the transcriptional repressor B-cell lymphoma-6 protein (BCL-6) was markedly enhanced by phenformin and AICAR, the repression of sPLA2 gene occurs through a mechanism independent of BCL-6 DNA binding site. In addition we show that activation of AMPK limits IL-1β-induced NF-κB pathway activation. Our results indicate that BCL-6, once activated by AMPK, functions as a competitor of the IL-1β induced NF-κB transcription complex. Our findings provide insights on a new anti-inflammatory pathway linking phenformin, AMPK and molecular control of sPLA2 IIA gene expression in VSMCs. PMID:26162096

  1. Topological phase transitions in group IV-VI semiconductors by phonons

    NASA Astrophysics Data System (ADS)

    Kim, Jinwoong; Jhi, Seung-Hoon

    2015-09-01

    The topological insulator has an intriguing electronic structure in that it has nontrivial topology enforcing the helical Dirac fermionic states at interfaces to the band insulators. Protected by the time-reversal symmetry and finite band gaps in the bulk, the topology is immune to external nonmagnetic perturbations. One essential question is whether elementary excitations in solids like phonons can trigger a transition in the topological property of the electronic structures. Here we investigate the development of topological insulating phases in IV-VI compounds under dynamic lattice deformations using first-principles calculations. Unlike the static state of topological phases at equilibrium conditions, we show that nontrivial topological phases are induced in the compounds by the dynamic lattice deformations from selective phonon modes. Calculations of the time-reversal polarization show that the Z2 invariant of the compounds is flipped by the selective phonon modes and that the compounds exhibit oscillating topological phases upon dynamic lattice deformations.

  2. Restoration of on-time embryo implantation corrects the timing of parturition in cytosolic phospholipase A2 group IVA deficient mice.

    PubMed

    Brown, Naoko; Morrow, Jason D; Slaughter, James C; Paria, Bibhash C; Reese, Jeff

    2009-12-01

    Cytosolic phospholipase A2 (cPLA2, PLA2G4A) catalyzes the release of arachidonic acid for prostaglandin synthesis by cyclooxygenase 1 (PTGS1) and cyclooxygenase 2 (PTGS2). Mice with Pla2g4a deficiency have parturition delay and other reproductive deficits, including deferred onset of implantation, crowding of implantation sites, and small litters. In this study, we examined the contribution of PLA2G4A to parturition in mice. Pla2g4a mRNA and protein expression were discretely localized in the term and preterm uterine luminal epithelium and colocalized with Ptgs1, but not Ptgs2, expression. The levels of PGE2, PGF2alpha, 6-keto-PGF1alpha, and TxB2 were significantly decreased in Pla2g4a-null uterine tissues, similar to Ptgs1-null uteri, consistent with predominance of PLA2G4A-PTGS1-mediated prostaglandin synthesis in preparation for murine parturition. Litter size was strongly associated with the timing of parturition in Pla2g4a-null mice but could not fully account for the parturition delay. Pla2g4a-null females that received PGE2 + carbaprostacyclin at the time of implantation delivered earlier (20.5 +/- 0.2 days vs. 21.6 +/- 0.2 days, P < 0.01), although litter size was not improved (4.6 vs. 4.4 pups per litter, P = 0.6). After correction for small litter size, multivariate analysis indicated that Pla2g4a-null mice given prostaglandin treatment to improve implantation timing had gestational length that was similar to wild-type and Pla2g4a heterozygous mice. These results indicate that, despite specific Pla2g4a expression and function in term gestation uteri, the delayed parturition phenotype in Pla2g4a-null mice is primarily due to deferral of implantation. The role of PLA2G4A in timely parturition appears to be critically related to its actions in early pregnancy.

  3. Expression analysis of the group IIA secretory phospholipase A(2) in mice with differential susceptibility to azoxymethane-induced colon tumorigenesis.

    PubMed

    Papanikolaou, A; Wang, Q S; Mulherkar, R; Bolt, A; Rosenberg, D W

    2000-02-01

    The murine non-pancreatic secretory phospholipase A(2) (sPLA(2)) has been proposed as a tumor modifier of multiple intestinal neoplasia (Min). A genetic polymorphism in the mouse gene that causes a disruption in exon 3 results in loss of functional protein. Mouse strains with a disrupted sPLA(2) gene are susceptible to the Min phenotype and develop numerous intestinal polyps, whereas mice with normal sPLA(2) develop only a limited number of polyps. The following study was undertaken to test the hypothesis that sPLA(2) plays an equivalent role in murine susceptibility to the colon carcinogen azoxymethane (AOM). sPLA(2) status was confirmed by sequencing in mice that are highly susceptible (A/J), susceptible (SWR/J) and resistant (AKR/J) to AOM-induced tumorigenesis. Constitutive expression of sPLA(2) mRNA was compared in small intestine and colon of untreated mice using semi-quantitative RT-PCR. Whereas mRNA expression was nearly absent in A/J mice, AKR/J mice exhibited extensive expression throughout the intestine. Despite the wild-type sPLA(2) gene, colonic mRNA expression in SWR/J mice was significantly lower relative to AKR/J. Immunohistochemical analysis of sPLA(2) protein confirmed the mRNA data. The effect of AOM on colonic sPLA(2) expression was also examined. Twenty-four weeks after the last of six weekly injections of AOM (10 mg/kg i.p.), RT-PCR analysis of distal colons revealed a significant increase in mRNA in normal-appearing epithelium and tumor tissue from AOM-treated mice relative to controls. However, there was no corresponding increase in protein expression in A/J mice. The absence of sPLA(2) expression within control colons of tumor-susceptible A/J mice together with low expression in SWR/J colons is consistent with its potential role as an intestinal tumor modifier, but the carcinogen-induced increase in expression raises doubts as to the significance of sPLA(2) in inhibiting carcinogenesis.

  4. Holistic medicine IV: principles of existential holistic group therapy and the holistic process of healing in a group setting.

    PubMed

    Ventegodt, Søren; Andersen, Niels Jørgen; Merrick, Joav

    2003-12-23

    In existential holistic group therapy, the whole person heals in accordance with the holistic process theory and the life mission theory. Existential group psychotherapy addresses the emotional aspect of the human mind related to death, freedom, isolation, and meaninglessness, while existential holistic group therapy addresses the state of the person"s wholeness. This includes the body, the person's philosophy of life, and often also love, purpose of life, and the spiritual dimension, to the same extent as it addresses the emotional psyche and sexuality, and it is thus much broader than traditional psychotherapy. Where existential psychotherapy is rather depressing concerning the fundamental human condition, existential holistic therapy conceives life to be basically good. The fundamentals in existential holistic therapy are that everybody has the potential for healing themselves to become loving, joyful, sexually attractive, strong, and gifted, which is a message that most patients welcome. While the patient is suffering and fighting to get through life, the most important job for the holistic therapist is to keep a positive perspective of life. In accordance with these fundamentals, many participants in holistic group therapy will have positive emotional experiences, often of an unknown intensity, and these experiences appear to transform their lives within only a few days or weeks of therapy. An important idea of the course is Bohm's concept of "holo-movement" in the group, resulting from intense coherence between the group members. When the group comes together, the individual will be linked to the totality and the great movement forward towards love, consciousness, and happiness will happen collectively--if it happens at all. This gives the individual the feeling that everything that happens is right, important, and valuable for all the participants at the same time. Native Americans and other premodern people refer to this experience as "the spiritual design

  5. Hydroxypyridinonate complex stability of group (IV) metals and tetravalent f-block elements: the key to the next generation of chelating agents for radiopharmaceuticals.

    PubMed

    Sturzbecher-Hoehne, Manuel; Choi, Taylor A; Abergel, Rebecca J

    2015-04-06

    The solution thermodynamics of the water-soluble complexes formed between 3,4,3-LI(1,2-HOPO) and Zr(IV) or Pu(IV) were investigated to establish the metal coordination properties of this octadentate chelating agent. Stability constants log β110 = 43.1 ± 0.6 and 43.5 ± 0.7 were determined for [Zr(IV)(3,4,3-LI(1,2-HOPO))] and [Pu(IV)(3,4,3-LI(1,2-HOPO))], respectively, by spectrophotometric competition titrations against Ce(IV). Such high thermodynamic stabilities not only confirm the unparalleled Pu(IV) affinity of 3,4,3-LI(1,2-HOPO) as a decorporation agent but also corroborate the great potential of hydroxypyridinonate ligands as new (89)Zr-chelating platforms for immuno-PET applications. These experimental values are in excellent agreement with previous estimates and are discussed with respect to ionic radius and electronic configuration, in comparison with those of Ce(IV) and Th(IV). Furthermore, a liquid chromatography assay combined with mass spectrometric detection was developed to probe the separation of the neutral [M(IV)(3,4,3-LI(1,2-HOPO))] complex species (M = Zr, Ce, Th, and Pu), providing additional insight into the coordination differences between group IV and tetravalent f-block metals and on the role of d and f orbitals in bonding interactions.

  6. Roles of various phospholipases A2 in providing lysophospholipid acceptors for fatty acid phospholipid incorporation and remodelling.

    PubMed Central

    Balsinde, Jesús

    2002-01-01

    In the present study the lysophospholipid sources for arachidonic (AA) and eicosapentaenoic acid (EPA) incorporation into and redistribution within the phospholipids of phorbol-ester-differentiated U937 cells was investigated. Initially, AA incorporated primarily into choline glycerophospholipids (PC), whereas EPA incorporated mainly into ethanolamine glycerophospholipids (PE). Bromoenol lactone (BEL), an inhibitor of the Group VI Ca2+-independent phospholipase A2 (iPLA2), diminished both lysophosphatidylcholine levels and the incorporation of AA into phospholipids. However BEL had little effect on EPA incorporation. In concanavalin A-activated cells, EPA, but not AA, incorporation was also affected by methyl arachidonyl fluorophosphonate (MAFP), suggesting an additional role for the group IV cytosolic phospholipase A2. In the activated cells AA and EPA did not compete with each other for incorporation, indicating that the pathways for AA and EPA incorporation are partially different. The AA and EPA initially incorporated into PC slowly moved to PE in a process that took several hours. The transfer of AA and EPA from PC to PE was not inhibited by BEL, MAFP or LY311727 [3-(3-acetamide 1-benzyl-2-ethylindolyl-5-oxy)propanesulphonic acid], raising the possibility that an as-yet-undetermined phospholipase A2 may be involved in fatty acid phospholipid remodelling. A strong candidate to be involved in these reactions is a novel Ca2+-independent phospholipase A2 that, unlike all known iPLA2s, is resistant to inhibition by BEL and also to MAFP and LY311727. The enzyme activity cleaves both PC and PE and is thus able to provide the lysoPC and lysoPE acceptors required for the fatty acid acylation reactions. PMID:12049633

  7. Consistent Multigroup Theory Enabling Accurate Course-Group Simulation of Gen IV Reactors

    SciTech Connect

    Rahnema, Farzad; Haghighat, Alireza; Ougouag, Abderrafi

    2013-11-29

    The objective of this proposal is the development of a consistent multi-group theory that accurately accounts for the energy-angle coupling associated with collapsed-group cross sections. This will allow for coarse-group transport and diffusion theory calculations that exhibit continuous energy accuracy and implicitly treat cross- section resonances. This is of particular importance when considering the highly heterogeneous and optically thin reactor designs within the Next Generation Nuclear Plant (NGNP) framework. In such reactors, ignoring the influence of anisotropy in the angular flux on the collapsed cross section, especially at the interface between core and reflector near which control rods are located, results in inaccurate estimates of the rod worth, a serious safety concern. The scope of this project will include the development and verification of a new multi-group theory enabling high-fidelity transport and diffusion calculations in coarse groups, as well as a methodology for the implementation of this method in existing codes. This will allow for a higher accuracy solution of reactor problems while using fewer groups and will reduce the computational expense. The proposed research represents a fundamental advancement in the understanding and improvement of multi- group theory for reactor analysis.

  8. Physical activity levels during phase IV cardiac rehabilitation in a group of male myocardial infarction patients

    PubMed Central

    Woolf-May, K; Bird, S; MacIntyre, P

    2005-01-01

    Objective: To determine physical activity levels during phase IV cardiac rehabilitation in 31 male myocardial infarction patients (median age 62, range 53–77 years). Methods: Patients recorded daily physical activity over 16 weeks in a diary. Diaries were analysed for total general physical activity (TGPA), leisure time physical activity (LTPA), and "active for life" exercise classes (AFL). Pre- and post-observation period (OP) subjects underwent a 10 m shuttle walking test (SWT) to determine changes in aerobic fitness. Rate of perceived exertion (RPE) determined exercise intensity. Estimated gross energy expenditure (EEE) was determined by a regression equation between RPE and Vo2 (l min–1) during SWT. A total of 97% of subjects were on lipid lowering medication. Results: There were no correlations between Vo2 (l min–1) and body mass, therefore kcal min–1 indicated activity intensity. There were no significant changes in physical activity patterns or in aerobic fitness. Estimated total LTPA (median 1376, range 128–3380 kcal week–1) was less than that recommended to improve aerobic fitness and/or slow progression of coronary artery disease. Sixteen subjects attended a median of 29 (range 1–46) AFL during LTPA; one way ANOVA showed these subjects worked at greater EEE (AFL, n = 16, 6.6 (standard deviation 1.4) v no-AFL, n = 15, 5.1 (1.8) EEE kcal min–1, p = 0.017). Conclusion: Physical activity was stable, but patients' EEE appeared insufficient to improve aerobic fitness or slow progression of coronary artery disease. It was suggested that the promotion of LTPA and the availability of AFL classes should be reconsidered. PMID:15728680

  9. Giant piezoelectricity of monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS

    NASA Astrophysics Data System (ADS)

    Fei, Ruixiang; Li, Wenbin; Li, Ju; Yang, Li

    2015-10-01

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique "puckered" C2v symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  10. Giant piezoelectricity of monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS

    SciTech Connect

    Fei, Ruixiang; Yang, Li; Li, Wenbin; Li, Ju

    2015-10-26

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS{sub 2} and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique “puckered” C{sub 2v} symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  11. Ectopically expressed pro-group X secretory phospholipase A2 is proteolytically activated in mouse adrenal cells by furin-like proprotein convertases: implications for the regulation of adrenal steroidogenesis.

    PubMed

    Layne, Joseph D; Shridas, Preetha; Webb, Nancy R

    2015-03-20

    Group X secretory phospholipase A2 (GX sPLA2) hydrolyzes mammalian cell membranes, liberating free fatty acids and lysophospholipids. GX sPLA2 is produced as a pro-enzyme (pro-GX sPLA2) that contains an N-terminal 11-amino acid propeptide ending in a dibasic motif, suggesting cleavage by a furin-like proprotein convertase (PC). Although propeptide cleavage is clearly required for enzymatic activity, the protease(s) responsible for pro-GX sPLA2 activation have not been identified. We previously reported that GX sPLA2 negatively regulates adrenal glucocorticoid production, likely by suppressing liver X receptor-mediated activation of steroidogenic acute regulatory protein expression. In this study, using a FLAG epitope-tagged pro-GX sPLA2 expression construct (FLAG-pro-GX sPLA2), we determined that adrenocorticotropic hormone (ACTH) enhanced FLAG-pro-GX sPLA2 processing and phospholipase activity secreted by Y1 adrenal cells. ACTH increased the expression of furin and PCSK6, but not other members of the PC family, in Y1 cells. Overexpression of furin and PCSK6 in HEK 293 cells significantly enhanced FLAG-pro-GX sPLA2 processing, whereas siRNA-mediated knockdown of both PCs almost completely abolished FLAG-pro-GX sPLA2 processing in Y1 cells. Expression of either furin or PCSK6 enhanced the ability of GX sPLA2 to suppress liver X receptor reporter activity. The PC inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethyl ketone significantly suppressed FLAG-pro-GX sPLA2 processing and sPLA2 activity in Y1 cells, and it significantly attenuated GX sPLA2-dependent inhibition of steroidogenic acute regulatory protein expression and progesterone production. These findings provide strong evidence that pro-GX sPLA2 is a substrate for furin and PCSK6 proteolytic processing and define a novel mechanism for regulating corticosteroid production in adrenal cells.

  12. Work group IV: Future directions for measures of the food and physical activity environments.

    PubMed

    Story, Mary; Giles-Corti, Billie; Yaroch, Amy Lazarus; Cummins, Steven; Frank, Lawrence Douglas; Huang, Terry T-K; Lewis, LaVonna Blair

    2009-04-01

    Much progress has been made in the past 5 to 10 years in measuring and understanding the impact of the food and physical activity environments on behavioral outcomes. Nevertheless, this research is in its infancy. A work group was convened to identify current evidence gaps and barriers in food and physical activity environments and policy research measures, and develop recommendations to guide future directions for measurement and methodologic research efforts. A nominal group process was used to determine six priority areas for food and physical activity environments and policy measures to move the field forward by 2015, including: (1) identify relevant factors in the food and physical activity environments to measure, including those most amenable to change; (2) improve understanding of mechanisms for relationships between the environment and physical activity, diet, and obesity; (3) develop simplified measures that are sensitive to change, valid for different population groups and settings, and responsive to changing trends; (4) evaluate natural experiments to improve understanding of food and physical activity environments and their impact on behaviors and weight; (5) establish surveillance systems to predict and track change over time; and (6) develop standards for adopting effective health-promoting changes to the food and physical activity environments. The recommendations emanating from the work group highlight actions required to advance policy-relevant research related to food and physical activity environments.

  13. Compact groups in theory and practice - IV. The connection to large-scale structure

    NASA Astrophysics Data System (ADS)

    Mendel, J. Trevor; Ellison, Sara L.; Simard, Luc; Patton, David R.; McConnachie, Alan W.

    2011-12-01

    We investigate the properties of photometrically selected compact groups (CGs) in the Sloan Digital Sky Survey. In this paper, the fourth in a series, we focus on understanding the characteristics of our observed CG sample with particular attention paid to quantifying and removing contamination from projected foreground or background galaxies. Based on a simple comparison of pairwise redshift likelihoods, we find that approximately half of CGs in the parent sample contain one or more projected (interloping) members; our final clean sample contains 4566 galaxies in 1086 CGs. We show that half of the remaining CGs are associated with rich groups (or clusters), i.e. they are embedded sub-structure. The other half have spatial distributions and number-density profiles consistent with the interpretation that they are either independently distributed structures within the field (i.e. they are isolated) or associated with relatively poor structures. Comparisons of late-type and red-sequence fractions in radial annuli show that galaxies around apparently isolated CGs resemble the field population by 300 to 500 kpc from the group centre. In contrast, the galaxy population surrounding embedded CGs appears to remain distinct from the field out beyond 1 to 2 Mpc, consistent with results for rich groups. We take this as additional evidence that the observed distinction between CGs, i.e. isolated versus embedded, is a separation between different host environments.

  14. Genetic improvement of U.S. soybean in Maturity Groups II, III, and IV

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean [Glycine max (L.) Merr.] improvement via plant breeding has been critical for the success of the crop. The objective of this study was to quantify genetic change in yield and other traits that occurred over the past 80 years of North American soybean breeding in maturity groups (MGs) II, III...

  15. Phospholipases and their industrial applications.

    PubMed

    De Maria, L; Vind, J; Oxenbøll, K M; Svendsen, A; Patkar, S

    2007-02-01

    Phospholipids are present in all living organisms. They are a major component of all biological membranes, along with glycolipids and cholesterol. Enzymes aimed at modifying phospholipids, namely, phospholipases, are consequently widespread in nature, playing very diverse roles from aggression in snake venom to signal transduction and digestion in humans. In this review, we give a general overview of phospholipases A1, A2, C and D from a sequence and structural perspective and their industrial application. The use of phospholipases in industrial processes has grown hand-in-hand with our ability to clone and express the genes in microbial hosts with commercially attractive amounts. Further, the use in industrial processes is increasing by optimizing the enzymes by protein engineering. Here, we give a perspective on the work done to date to express phospholipases in heterologous hosts and the efforts to optimize them by protein engineering. We will draw attention to the industrial processes where phospholipases play a key role and show how the use of a phospholipase for oil degumming leads to substantial environmental benefits. This illustrates a very general trend: the use of enzymes as an alternative to chemical processes to make products often provides a cleaner solution for the industrial processes. In a world with great demands on non-polluting, energy saving technical solutions--white biotechnology is a strong alternative.

  16. Selective Inhibition of Human Group IIA-secreted Phospholipase A2 (hGIIA) Signaling Reveals Arachidonic Acid Metabolism Is Associated with Colocalization of hGIIA to Vimentin in Rheumatoid Synoviocytes*

    PubMed Central

    Lee, Lawrence K.; Bryant, Katherine J.; Bouveret, Romaric; Lei, Pei-Wen; Duff, Anthony P.; Harrop, Stephen J.; Huang, Edwin P.; Harvey, Richard P.; Gelb, Michael H.; Gray, Peter P.; Curmi, Paul M.; Cunningham, Anne M.; Church, W. Bret; Scott, Kieran F.

    2013-01-01

    Human group IIA secreted phospholipase A2 (hGIIA) promotes tumor growth and inflammation and can act independently of its well described catalytic lipase activity via an alternative poorly understood signaling pathway. With six chemically diverse inhibitors we show that it is possible to selectively inhibit hGIIA signaling over catalysis, and x-ray crystal structures illustrate that signaling involves a pharmacologically distinct surface to the catalytic site. We demonstrate in rheumatoid fibroblast-like synoviocytes that non-catalytic signaling is associated with rapid internalization of the enzyme and colocalization with vimentin. Trafficking of exogenous hGIIA was monitored with immunofluorescence studies, which revealed that vimentin localization is disrupted by inhibitors of signaling that belong to a rare class of small molecule inhibitors that modulate protein-protein interactions. This study provides structural and pharmacological evidence for an association between vimentin, hGIIA, and arachidonic acid metabolism in synovial inflammation, avenues for selective interrogation of hGIIA signaling, and new strategies for therapeutic hGIIA inhibitor design. PMID:23482564

  17. Open-framework clathrates of group IV elements: Synthesis, structure, and characterization

    NASA Astrophysics Data System (ADS)

    Ramachandran, Ganesh K.

    ˜ 41 mO·cm. The compressional behavior of the expanded form of silicon, the cubic Si136 clathrate, is studied by energy dispersive x-ray diffraction in a diamond anvil cell experiment. The ambient temperature bulk modulus and its pressure derivative are determined to be K0 = 90(3) GPa and K0' = 5.2(8). At pressures between 8--10 GPa, the structure transforms into the thermodynamically stable beta-Sn phase. However, this metastable transition from Si136 to the beta-Sn structure should occur at much lower pressure (3--4 GPa), from consideration of free energy-pressure relations. We relate this observation to the absence of a convenient low-energy pathway far the IV- to VI-fold coordination change involved in the transition from Si136 to beta-Sn.

  18. IGORR-IV -- Proceedings of the fourth meeting of the International Group on Research Reactors

    SciTech Connect

    Rosenbalm, K.F.

    1995-12-31

    The International Group on Research Reactors was formed to facilitate the sharing of knowledge and experience among those institutions and individuals who are actively working to design, build, and promote new research reactors or to make significant upgrades to existing facilities. Twenty-nine papers were presented in five sessions and written versions of the papers or hard copies of the vugraphs used are published in these proceedings. The five sessions were: (1) Operating Research Reactors and Facility Upgrades; (2) Research Reactors in Design and Construction; (3) ANS Closeout Activities; (4) and (5) Research, Development, and Analysis Results.

  19. Long range ordered alloys modified by group IV-B metals

    DOEpatents

    Liu, Chain T.; Inouye, Henry; Schaffhauser, Anthony C.

    1983-01-01

    Ductile long range ordered alloys having high critical ordering temperatures exist in the (V,M)(Fe,Ni,Co).sub.3 system having the composition comprising by weight 20.6%-22.6% V, 14-50% Fe, 0-64% Co, and 0-40% Ni, and 0.4-1.4% M, where M is a metal selected from the group consisting of Ti, Zr, Hf, and their mixtures. These modified alloys have an electron density no greater than 8.00 and exhibit marked increases at elevated temperature in ductility and other mechanical properties over previously known ordered alloys.

  20. Viridans Group Streptococci Are Donors in Horizontal Transfer of Topoisomerase IV Genes to Streptococcus pneumoniae

    PubMed Central

    Balsalobre, Luz; Ferrándiz, María José; Liñares, Josefina; Tubau, Fe; de la Campa, Adela G.

    2003-01-01

    A total of 46 ciprofloxacin-resistant (Cipr) Streptococcus pneumoniae strains were isolated from 1991 to 2001 at the Hospital of Bellvitge. Five of these strains showed unexpectedly high rates of nucleotide variations in the quinolone resistance-determining regions (QRDRs) of their parC, parE, and gyrA genes. The nucleotide sequence of the full-length parC, parE, and gyrA genes of one of these isolates revealed a mosaic structure compatible with an interspecific recombination origin. Southern blot analysis and nucleotide sequence determinations showed the presence of an ant-like gene in the intergenic parE-parC regions of the S. pneumoniae Cipr isolates with high rates of variations in their parE and parC QRDRs. The ant-like gene was absent from typical S. pneumoniae strains, whereas it was present in the intergenic parE-parC regions of the viridans group streptococci (Streptococcus mitis and Streptococcus oralis). These results suggest that the viridans group streptococci are acting as donors in the horizontal transfer of fluoroquinolone resistance genes to S. pneumoniae. PMID:12821449

  1. Planetary nebulae as standard candles. IV - A test in the Leo I group

    NASA Technical Reports Server (NTRS)

    Ciardullo, Robin; Jacoby, George H.; Ford, Holland C.

    1989-01-01

    In this paper, PN are used to determine accurate distances to three galaxies in the Leo I group - The E0 giant elliptical NGC 3379, its optical companion, the SB0 spiral NGC 3384, and the smaller E6 elliptical NGC 3377. In all three galaxies, the luminosity-specific PN number densities are roughly the same, and the derived stellar death rates are in remarkable agreement with the predictions of stellar evolution theory. It is shown that the shape of the forbidden O III 5007 A PN luminosity function is the same in each galaxy and indistinguishable from that observed in M31 and M81. It is concluded that the PN luminosity function is an excellent standard candle for early-type galaxies.

  2. Terahertz emission upon the band-to-band excitation of Group-IV semiconductors at room temperature

    SciTech Connect

    Zakhar’in, A. O.; Bobylev, A. V.; Egorov, S. V.; Andrianov, A. V.

    2015-03-15

    Terahertz emission upon the band-to-band excitation of Group-IV semiconductors (Si:B and Ge:Ga) at room temperature by a semiconductor laser emitting in the visible range (660 nm) is observed and investigated. It is established that, as the crystal temperature is elevated above room temperature, the emission intensity increases considerably, while the emission spectrum shifts to higher frequencies. The terahertz-emission spectra of germanium and silicon are quite similar to each other. The pump-intensity dependence of the terahertz-emission intensity is nearly linear. The above features make it possible to attribute the observed terahertz emission to the effect of crystal heating by absorbed pump radiation.

  3. Enhanced Telecom Emission from Single Group-IV Quantum Dots by Precise CMOS-Compatible Positioning in Photonic Crystal Cavities.

    PubMed

    Schatzl, Magdalena; Hackl, Florian; Glaser, Martin; Rauter, Patrick; Brehm, Moritz; Spindlberger, Lukas; Simbula, Angelica; Galli, Matteo; Fromherz, Thomas; Schäffler, Friedrich

    2017-03-15

    Efficient coupling to integrated high-quality-factor cavities is crucial for the employment of germanium quantum dot (QD) emitters in future monolithic silicon-based optoelectronic platforms. We report on strongly enhanced emission from single Ge QDs into L3 photonic crystal resonator (PCR) modes based on precise positioning of these dots at the maximum of the respective mode field energy density. Perfect site control of Ge QDs grown on prepatterned silicon-on-insulator substrates was exploited to fabricate in one processing run almost 300 PCRs containing single QDs in systematically varying positions within the cavities. Extensive photoluminescence studies on this cavity chip enable a direct evaluation of the position-dependent coupling efficiency between single dots and selected cavity modes. The experimental results demonstrate the great potential of the approach allowing CMOS-compatible parallel fabrication of arrays of spatially matched dot/cavity systems for group-IV-based data transfer or quantum optical systems in the telecom regime.

  4. Phospholipases in arterial tissue

    PubMed Central

    Eisenberg, S.; Stein, Y.; Stein, O.

    1969-01-01

    The role of phospholipases in the regulation of the changing phospholipid composition of normal human aortae with age was studied. Portions of grossly and histologically lesion-free ascending aortae from 16 females and 29 males obtained at autopsy, were analyzed for deoxyribonucleic acid (DNA), phospholipid, and cholesterol content and phospholipid composition. Enzymic activity toward four substrates, lecithin (LE), phosphatidyl ethanolamine, lysolecithin, and sphingomyelin (SP), was determined on portions of the same homogenate. By regression analysis for correlation between all determinations and age the following results were obtained: (a) total phospholipids and choleserol increased linearly with age; (b) the increase in sphingomyelin accounted for about 70% of the phospholipid increment; (c) hydrolysis of lecithin and phosphatidyl ethanolamine increased markedly with age, that of lysolecithin only moderately; (d) hydrolysis of sphingomyelin decreased with age; and (e) an inverse relation between the SP/LE ratio and age and sphingomyelinase/lecithinase activity and age was obtained. These results were interpreted to indicate that a causal relation exists between the fall in sphingomyelinase activity, both absolute and relative to lecithinase activity, and the accumulation of sphingomyelin with age. PMID:5355343

  5. Synthesis, structural characterization and antimicrobial activities of diorganotin(IV) complexes with azo-imino carboxylic acid ligand: Crystal structure and topological study of a doubly phenoxide-bridged dimeric dimethyltin(IV) complex appended with free carboxylic acid groups

    NASA Astrophysics Data System (ADS)

    Roy, Manojit; Roy, Subhadip; Devi, N. Manglembi; Singh, Ch. Brajakishor; Singh, Keisham Surjit

    2016-09-01

    Diorganotin(IV) complexes appended with free carboxylic acids were synthesized by reacting diorganotin(IV) dichlorides [R2SnCl2; R = Me (1), Bu (2) and Ph (3)] with an azo-imino carboxylic acid ligand i.e. 2-{4-hydroxy-3-[(2-hydroxyphenylimino)methyl]phenylazo}benzoic acid in presence of triethylamine. The complexes were characterized by elemental analysis, IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The structure of 1 in solid state has been determined by X-ray crystallography. Crystal structure of 1 reveals that the compound crystallizes in monoclinic space group P21/c and is a dimeric dimethyltin(IV) complex appended with free carboxylic acid groups. In the structure of 1, the Sn(IV) atoms are hexacoordinated and have a distorted octahedral coordination geometry in which two phenoxy oxygen atoms and the azomethine nitrogen atom of the ligand coordinate to each tin atom. One of the phenoxy oxygen atom bridges the two tin centers resulting in a planar Sn2O2 core. Topological analysis is used for the description of molecular packing in 1. Tin NMR spectroscopy study indicates that the complexes have five coordinate geometry around tin atom in solution state. Since the complexes have free carboxylic acids, these compounds could be further used as potential metallo-ligands for the synthesis of other complexes. The synthesized diorganotin(IV) complexes were also screened for their antimicrobial activities and compound 2 showed effective antimicrobial activities.

  6. The effect of ω-fatty acids on the expression of phospholipase A2 group 2A in human gastric cancer patients

    PubMed Central

    Shariati, Mahboube; Aghaei, Mahmoud; Movahedian, Ahmad; Somi, Mohammad Hosein; Dolatkhah, Homayun; Aghazade, Ahmad Mirza

    2016-01-01

    Background: Studies show that polyunsaturated fatty acids (PUFAs) may have an inhibitory role in carcinogenesis. It was previously shown that PLA2 group 2A (PLA2G2A) messenger RNA (mRNA) expression is associated with less frequent metastasis and longer survival in gastric adenocarcinoma. This study intends to investigate the effect of PUFAs on the expression of PLA2G2A in patients with gastric cancer. Materials and Methods: Thirty-four patients with gastric cancer (GC) were randomly divided into two groups. The first group received cisplatin medication. The second group received cisplatin medication and supplements of ω-fatty acids for three courses. The total RNA was extracted from the tissues and cDNA was synthesized. The gene expression of PLA2G2A was evaluated by the real-time polymerase chain reaction (PCR) method. To confirm the changes in gene expression, frozen section was utilized. The frozen tissue samples were sectioned and stained using the immunohistochemistry technique. Results: After chemotherapy and chemotherapy plus supplement, the relative mean of PLA2G2A gene expression increased 1.5 ± 0.5-fold and 7.4 ± 2.6-fold, respectively (P = 0.006). The relative mean of gene expression in patients who received cisplatin and ω-fatty acids supplement increased more significantly (7.5 ± 3.3-fold) than in patients who received only cisplatin (P = 0.016). Conclusion: It was found that PUFAs increased the gene and protein expression of PLA2G2A in gastric cancer. Concerning the fact that studies reveal protective function of PLA2G2A in gastric cancer, it is suggested that increased expression of PLA2G2A is helpful. Furthermore, PUFAs can be considered as a useful therapeutic supplement for patients with gastric cancer. PMID:27904556

  7. Assay strategies and methods for phospholipases

    SciTech Connect

    Reynolds, L.J.; Washburn, W.N.; Deems, R.A.; Dennis, E.A.

    1991-01-01

    Of the general considerations discussed, the two issues which are most important in choosing an assay are (1) what sensitivity is required to assay a particular enzyme and (2) whether the assay must be continuous. One can narrow the options further by considering substrate availability, enzyme specificity, assay convenience, or the presence of incompatible side reactions. In addition, the specific preference of a particular phospholipase for polar head group, micellar versus vesicular substrates, and anionic versus nonionic detergents may further restrict the options. Of the many assays described in this chapter, several have limited applicability or serious drawbacks and are not commonly employed. The most commonly used phospholipase assays are the radioactive TLC assay and the pH-stat assay. The TLC assay is probably the most accurate, sensitive assay available. These aspects often outweigh the disadvantages of being discontinuous, tedious, and expensive. The radioactive E. coli assay has become popular recently as an alternative to the TLC assay for the purification of the mammalian nonpancreatic phospholipases. The assay is less time consuming and less expensive than the TLC assay, but it is not appropriate when careful kinetics are required. Where less sensitivity is needed, or when a continuous assay is necessary, the pH-stat assay is often employed. With purified enzymes, when free thiol groups are not present, a spectrophotometric thiol assay can be used. This assay is {approximately} as sensitive as the pH-stat assay but is more convenient and more reproducible, although the substrate is not available commercially. Despite the many assay choices available, the search continues for a convenient, generally applicable assay that is both sensitive and continuous.

  8. Detection and characterization of extracellular phospholipase A sub 2 in pleural effusion of patients with tuberculosis

    SciTech Connect

    Baek, Suk Hwan; Chang, Hyeun Wook ); Takayama, Kiyoshi; Kudo, Ichiro; Inoue, Keizo ); Lee, Hyun Woo; Do Jun Young )

    1991-01-01

    Extracellular phospholipase A{sub 2} activity has been identified in pleural fluid of patients with tuberculosis. This enzyme is a calcium requiring protein and has a pH optimum of 10.0. The enzyme was inhibited by the active site-directed histidine reagent, {rho}-bromophenacyl bromide. Ionic and non-ionic detergents, or the sulfhydryl reagent dithiothreitol, caused loss of enzyme activity. When substrate specificity was tested using 2-(1-{sup 14}C)linoleoyl phospholipids as substrates, phosphatidylethanolamine was the best substrate, followed by phosphatidylserine and phosphatidylcholine. This phospholipase A{sub 2} showed high affinity for heparin, and was recognized by a monoclonal antibody raised against phospholipase A{sub 2} from human synovial fluid. These findings suggest that an extracellular phospholipase A{sub 2}, which may belong to the 14K group II phospholipase A{sub 2} family, exists in the pleural fluid of patients with tuberculosis.

  9. Diverse anisotropy of phonon transport in two-dimensional group IV-VI compounds: A comparative study

    NASA Astrophysics Data System (ADS)

    Qin, Guangzhao; Qin, Zhenzhen; Fang, Wu-Zhang; Zhang, Li-Chuan; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming; Su, Gang

    2016-05-01

    New classes of two-dimensional (2D) materials beyond graphene, including layered and non-layered, and their heterostructures, are currently attracting increasing interest due to their promising applications in nanoelectronics, optoelectronics and clean energy, where thermal transport is a fundamental physical parameter. In this paper, we systematically investigated the phonon transport properties of the 2D orthorhombic group IV-VI compounds of GeS, GeSe, SnS and SnSe by solving the Boltzmann transport equation (BTE) based on first-principles calculations. Despite their similar puckered (hinge-like) structure along the armchair direction as phosphorene, the four monolayer compounds possess diverse anisotropic properties in many aspects, such as phonon group velocity, Young's modulus and lattice thermal conductivity (κ), etc. Especially, the κ along the zigzag and armchair directions of monolayer GeS shows the strongest anisotropy while monolayer SnS and SnSe show almost isotropy in phonon transport. The origin of the diverse anisotropy is fully studied and the underlying mechanism is discussed in details. With limited size, the κ could be effectively lowered, and the anisotropy could be effectively modulated by nanostructuring, which would extend the applications to nanoscale thermoelectrics and thermal management. Our study offers fundamental understanding of the anisotropic phonon transport properties of 2D materials, and would be of significance for further study, modulation and applications in emerging technologies.

  10. A Clostridium Group IV Species Dominates and Suppresses a Mixed Culture Fermentation by Tolerance to Medium Chain Fatty Acids Products

    PubMed Central

    Andersen, Stephen J.; De Groof, Vicky; Khor, Way Cern; Roume, Hugo; Props, Ruben; Coma, Marta; Rabaey, Korneel

    2017-01-01

    A microbial community is engaged in a complex economy of cooperation and competition for carbon and energy. In engineered systems such as anaerobic digestion and fermentation, these relationships are exploited for conversion of a broad range of substrates into products, such as biogas, ethanol, and carboxylic acids. Medium chain fatty acids (MCFAs), for example, hexanoic acid, are valuable, energy dense microbial fermentation products, however, MCFA tend to exhibit microbial toxicity to a broad range of microorganisms at low concentrations. Here, we operated continuous mixed population MCFA fermentations on biorefinery thin stillage to investigate the community response associated with the production and toxicity of MCFA. In this study, an uncultured species from the Clostridium group IV (related to Clostridium sp. BS-1) became enriched in two independent reactors that produced hexanoic acid (up to 8.1 g L−1), octanoic acid (up to 3.2 g L−1), and trace concentrations of decanoic acid. Decanoic acid is reported here for the first time as a possible product of a Clostridium group IV species. Other significant species in the community, Lactobacillus spp. and Acetobacterium sp., generate intermediates in MCFA production, and their collapse in relative abundance resulted in an overall production decrease. A strong correlation was present between the community composition and both the hexanoic acid concentration (p = 0.026) and total volatile fatty acid concentration (p = 0.003). MCFA suppressed species related to Clostridium sp. CPB-6 and Lactobacillus spp. to a greater extent than others. The proportion of the species related to Clostridium sp. BS-1 over Clostridium sp. CPB-6 had a strong correlation with the concentration of octanoic acid (p = 0.003). The dominance of this species and the increase in MCFA resulted in an overall toxic effect on the mixed community, most significantly on the Lactobacillus spp., which resulted in a decrease in total

  11. Two-Dimensional Large Gap Topological Insulators with Tunable Rashba Spin-Orbit Coupling in Group-IV films.

    PubMed

    Zhang, Shou-Juan; Ji, Wei-Xiao; Zhang, Chang-Wen; Li, Ping; Wang, Pei-Ji

    2017-04-03

    The coexistence of nontrivial topology and giant Rashba splitting, however, has rare been observed in two-dimensional (2D) films, limiting severely its potential applications at room temperature. Here, we through first-principles calculations to propose a series of inversion-asymmetric group-IV films, ABZ2 (A ≠ B = Si, Ge, Sn, Pb; Z = F, Cl, Br), whose stability are confirmed by phonon spectrum calculations. The analyses of electronic structures reveal that they are intrinsic 2D TIs with a bulk gap as large as 0.74 eV, except for GeSiF2, SnSiCl2, GeSiCl2 and GeSiBr2 monolayers which can transform from normal to topological phases under appropriate tensile strain of 4, 4, 5, and 4%, respectively. The nontrivial topology is identified by Z2 topological invariant together with helical edge states, as well as the berry curvature of these systems. Another prominent intriguing feature is the giant Rashba spin splitting with a magnitude reaching 0.15 eV, the largest value reported in 2D films so far. The tunability of Rashba SOC and band topology can be realized through achievable compressive/tensile strains (-4 ~ 6%). Also, the BaTe semiconductor is an ideal substrate for growing ABZ2 films without destroying their nontrivial topology.

  12. Genome-Wide Association Study of Ureide Concentration in Diverse Maturity Group IV Soybean [Glycine max (L.) Merr.] Accessions

    PubMed Central

    Ray, Jeffery D.; Dhanapal, Arun Prabhu; Singh, Shardendu K.; Hoyos-Villegas, Valerio; Smith, James R.; Purcell, Larry C.; King, C. Andy; Boykin, Debbie; Cregan, Perry B.; Song, Qijian; Fritschi, Felix B.

    2015-01-01

    Ureides are the N-rich products of N-fixation that are transported from soybean nodules to the shoot. Ureides are known to accumulate in leaves in response to water-deficit stress, and this has been used to identify genotypes with reduced N-fixation sensitivity to drought. Our objectives in this research were to determine shoot ureide concentrations in 374 Maturity Group IV soybean accessions and to identify genomic regions associated with shoot ureide concentration. The accessions were grown at two locations (Columbia, MO, and Stuttgart, AR) in 2 yr (2009 and 2010) and characterized for ureide concentration at beginning flowering to full bloom. Average shoot ureide concentrations across all four environments (two locations and two years) and 374 accessions ranged from 12.4 to 33.1 µmol g−1 and were comparable to previously reported values. SNP–ureide associations within and across the four environments were assessed using 33,957 SNPs with a MAF ≥0.03. In total, 53 putative loci on 18 chromosomes were identified as associated with ureide concentration. Two of the putative loci were located near previously reported QTL associated with ureide concentration and 30 loci were located near genes associated with ureide metabolism. The remaining putative loci were not near chromosomal regions previously associated with shoot ureide concentration and may mark new genes involved in ureide metabolism. Ultimately, confirmation of these putative loci will provide new sources of variation for use in soybean breeding programs. PMID:26374596

  13. Nanosheets by design: The controllable synthesis of group IV-VI layered semiconductor chalcogenide nanostructures using colloidal chemistry

    NASA Astrophysics Data System (ADS)

    Vaughn, Dimitri D., II

    Nanosheets, a class of nanomaterials with two-dimensional structure and atomic or molecular scale thickness, have attracted a great deal of interest from the scientific community due to excellent physical properties and several promising applications in optoelectronics, energy conversion and storage, and catalysis. While advances in the synthesis of 2D nanostructures using top-down. chemical and physical strategies such as exfoliation and mechanical cleavage have been achieved, improved synthesis may be realized by applying bottom-up. colloidal strategies where nanosheets are built. directly from solution in an atomic layer-by-layer fashion. In this dissertation, I will discuss recent advances in the synthesis of semiconductor nanosheets with controllable lateral dimension, thickness, hierarchical structure, and porosity, specifically focusing on a class of group IV-VI layered semiconductor chalcogenides (GeS, GeSe, SnS, and SnSe) as a model system. Finally, I will highlight my efforts for expanding the synthetic framework mentioned above to access other materials, including the colloidal synthesis of germanium and Ge-based nanostructures.

  14. Two-Dimensional Large Gap Topological Insulators with Tunable Rashba Spin-Orbit Coupling in Group-IV films

    PubMed Central

    Zhang, Shou-juan; Ji, Wei-xiao; Zhang, Chang-wen; Li, Ping; Wang, Pei-ji

    2017-01-01

    The coexistence of nontrivial topology and giant Rashba splitting, however, has rare been observed in two-dimensional (2D) films, limiting severely its potential applications at room temperature. Here, we through first-principles calculations to propose a series of inversion-asymmetric group-IV films, ABZ2 (A ≠ B = Si, Ge, Sn, Pb; Z = F, Cl, Br), whose stability are confirmed by phonon spectrum calculations. The analyses of electronic structures reveal that they are intrinsic 2D TIs with a bulk gap as large as 0.74 eV, except for GeSiF2, SnSiCl2, GeSiCl2 and GeSiBr2 monolayers which can transform from normal to topological phases under appropriate tensile strain of 4, 4, 5, and 4%, respectively. The nontrivial topology is identified by Z2 topological invariant together with helical edge states, as well as the berry curvature of these systems. Another prominent intriguing feature is the giant Rashba spin splitting with a magnitude reaching 0.15 eV, the largest value reported in 2D films so far. The tunability of Rashba SOC and band topology can be realized through achievable compressive/tensile strains (−4 ~ 6%). Also, the BaTe semiconductor is an ideal substrate for growing ABZ2 films without destroying their nontrivial topology. PMID:28368035

  15. Enhanced Telecom Emission from Single Group-IV Quantum Dots by Precise CMOS-Compatible Positioning in Photonic Crystal Cavities

    PubMed Central

    2017-01-01

    Efficient coupling to integrated high-quality-factor cavities is crucial for the employment of germanium quantum dot (QD) emitters in future monolithic silicon-based optoelectronic platforms. We report on strongly enhanced emission from single Ge QDs into L3 photonic crystal resonator (PCR) modes based on precise positioning of these dots at the maximum of the respective mode field energy density. Perfect site control of Ge QDs grown on prepatterned silicon-on-insulator substrates was exploited to fabricate in one processing run almost 300 PCRs containing single QDs in systematically varying positions within the cavities. Extensive photoluminescence studies on this cavity chip enable a direct evaluation of the position-dependent coupling efficiency between single dots and selected cavity modes. The experimental results demonstrate the great potential of the approach allowing CMOS-compatible parallel fabrication of arrays of spatially matched dot/cavity systems for group-IV-based data transfer or quantum optical systems in the telecom regime. PMID:28345012

  16. Does estradiol have an impact on the dipeptidyl peptidase IV enzyme activity of the Prevotella intermedia group bacteria?

    PubMed

    Fteita, Dareen; Könönen, Eija; Gürsoy, Mervi; Söderling, Eva; Gürsoy, Ulvi Kahraman

    2015-12-01

    Initiation and development of pregnancy-associated gingivitis is seemingly related to the microbial shift towards specific gram-negative anaerobes in subgingival biofilms. It is known that Prevotella intermedia sensu lato is able to use estradiol as an alternative source of growth instead of vitamin K. The aim of the present study was to investigate the impact of estradiol on the bacterial dipeptidyl peptidase IV (DPPIV) enzyme activity in vitro as a virulent factor of the Prevotella intermedia group bacteria, namely P. intermedia, Prevotella nigrescens, Prevotella pallens, and Prevotella aurantiaca. In all experiments, 2 strains of each Prevotella species were used. Bacteria were incubated with the concentrations of 0, 30, 90, and 120 nmol/L of estradiol and were allowed to build biofilms at an air-solid interface. DPPIV activities of biofilms were measured kinetically during 20 min using a fluorometric assay. The enzyme activity was later related to the amount of protein produced by the same biofilm, reflecting the biofilm mass. Estradiol significantly increased DPPIV activities of the 8 Prevotella strains in a strain- and dose-dependent manner. In conclusion, our in vitro experiments indicate that estradiol regulates the DPPIV enzyme activity of P. intermedia, P. nigrescens, P. pallens, and P. aurantiaca strains differently. Our results may, at least partly, explain the role of estradiol to elicit a virulent state which contributes to the pathogenesis of pregnancy-related gingivitis.

  17. Validation of nuclear criticality safety software and 27 energy group ENDF/B-IV cross sections. Revision 1

    SciTech Connect

    Lee, B.L. Jr.; D`Aquila, D.M.

    1996-01-01

    The original validation report, POEF-T-3636, was documented in August 1994. The document was based on calculations that were executed during June through August 1992. The statistical analyses in Appendix C and Appendix D were completed in October 1993. This revision is written to clarify the margin of safety being used at Portsmouth for nuclear criticality safety calculations. This validation gives Portsmouth NCS personnel a basis for performing computerized KENO V.a calculations using the Lockheed Martin Nuclear Criticality Safety Software. The first portion of the document outlines basic information in regard to validation of NCSS using ENDF/B-IV 27-group cross sections on the IBM3090 at ORNL. A basic discussion of the NCSS system is provided, some discussion on the validation database and validation in general. Then follows a detailed description of the statistical analysis which was applied. The results of this validation indicate that the NCSS software may be used with confidence for criticality calculations at the Portsmouth Gaseous Diffusion Plant. For calculations of Portsmouth systems using the specified codes and systems covered by this validation, a maximum k{sub eff} including 2{sigma} of 0.9605 or lower shall be considered as subcritical to ensure a calculational margin of safety of 0.02. The validation of NCSS on the IBM 3090 at ORNL was extended to include NCSS on the IBM 3090 at K-25.

  18. The Fe Group Abundances in the B3 IV Standard ι Herculis Determined from ASTRAL II Observations

    NASA Astrophysics Data System (ADS)

    Peters, Geraldine J.; Proffitt, Charles R.; Adelman, Saul J.; Ayres, Thomas R.

    2017-01-01

    Iota Herculis is an ultrasharp-lined B3 IV star that historically has been considered as an abundance standard for the early B stars. This star was one of the targets in the HST Treasury Program Advanced Spectral Library II: Hot Stars (ASTRAL II) that produced uninterrupted spectra of high to medium resolution in the region 1150-3100 Å. The abundances for the Fe group elements (Ti, V, Cr, Mn, Fe, Co, & Ni) in ι Her were determined mostly from STIS E140H and E230H (resolving power of 114,000) observations. Measurable lines from the Fe group, except for a very few multiplets of Fe II, III are not found in optical spectra. Whereas the light elements are delivered to the ISM by core-collapse supernovae (CCSNe), the Fe group elements are believed to come mostly from low/intermediate mass binaries containing white dwarfs that undergo SNe Ia explosions. A single SNe Ia can deliver 0.5 solar masses of pure Fe (and maybe Mn) to the ISM compared with about 0.07 solar masses from a CCSNe. The HST/STIS data were supplemented with optical spectra obtained at the Dominion Astrophysical Observatory (resolving power about 60,000). The abundance analysis was carried through with the NLTE code TLUSTY/SYNSPEC (Hubeny & Lanz, ApJ, 439,875,1995). The model parameters adopted for the ι Her are Teff = 17750 ± 250 K, log g = 3.75 ± 0.05 dex, Vturb = 0 km s-1, and v sin i = 5 km s-1. Solar abundances appear to prevail for the lighter elements but the abundances of Fe group elements are 0.3 - 0.7 dex below solar values determined by Grevesse et al. (2010, Ap&SpSci, 328, 179). It appears that ι Her was formed in a region our Galaxy mostly enriched by CCSNe.The authors appreciate support from STScI grants HST-GO-09848 and HST-GO-13346. SJA was a guest observer at DAO.

  19. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... conditions; (ii) Debris; (iii) Temperature ranges; and (iv) Weather-related visibility. (b) The COTP may... tankers in Prince William Sound covered by § 155.1135) 12 hrs 36 hrs 60 hrs Great Lakes 18 hrs 42 hrs...

  20. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... conditions; (ii) Debris; (iii) Temperature ranges; and (iv) Weather-related visibility. (b) The COTP may... tankers in Prince William Sound covered by § 155.1135) 12 hrs 36 hrs 60 hrs Great Lakes 18 hrs 42 hrs...

  1. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... conditions; (ii) Debris; (iii) Temperature ranges; and (iv) Weather-related visibility. (b) The COTP may... tankers in Prince William Sound covered by § 155.1135) 12 hrs 36 hrs 60 hrs Great Lakes 18 hrs 42 hrs...

  2. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... conditions; (ii) Debris; (iii) Temperature ranges; and (iv) Weather-related visibility. (b) The COTP may... tankers in Prince William Sound covered by § 155.1135) 12 hrs 36 hrs 60 hrs Great Lakes 18 hrs 42 hrs...

  3. The Development and Evaluation of Training Methods for Group IV Personnel. 1. Orientation and Implementation of the Training Methods Development School (TMDS).

    ERIC Educational Resources Information Center

    Steinemann, John H.

    The investigation is part of continuing Navy research on the Trainability of Group IV (low ability) personnel intended to maximize the utilization and integration of marginal personnel in the fleet. An experimental Training Methods Development School (TMDS) was initiated to provide an experimental training program, with research controls, for…

  4. Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups

    ERIC Educational Resources Information Center

    Lieberman, Lauren; Lucas, Mark; Jones, Jeffery; Humphreys, Dan; Cody, Ann; Vaughn, Bev; Storms, Tommie

    2013-01-01

    "Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups" provides the the following articles: (1) "Sport Programming Offered by Camp Abilities and the United States Association for Blind Athletes" (Lauren Lieberman and Mark…

  5. † THE GROUP VIA CALCIUM-INDEPENDENT PHOSPHOLIPASE A2 (iPLA2β)1 PARTICIPATES IN ER STRESS-INDUCED INS-1 INSULINOMA CELL APOPTOSIS BY PROMOTING CERAMIDE GENERATION VIA HYDROLYSIS OF SPHINGOMYELINS BY NEUTRAL SPHINGOMYELINASE

    PubMed Central

    Lei, Xiao-Yong; Zhang, Sheng; Bohrer, Alan; Bao, Shunzhong; Song, Haowei; Ramanadham, Sasanka

    2008-01-01

    β-cell mass is regulated by a balance between β-cell growth and β-cell death, due to apoptosis. We previously reported that apoptosis of INS-1 insulinoma cells due to thapsigargin-induced ER stress was suppressed by inhibition of the Group VIA Ca2+-independent phospholipase A2 (iPLA2β), associated with increased ceramide generation, and that the effects of ER stress were amplified in INS-1 cells in which iPLA2β was over expressed (OE INS-1 cells). These findings suggested that iPLA2β and ceramides participate in ER stress-induced INS-1 cell apoptosis. Here, we addressed this possibility and also the source of the ceramides by examining the effects of ER stress in empty vector (V)-transfected and iPLA2β-OE INS-1 cells using apoptosis assays and immunoblotting, quantitative PCR, and mass spectrometry analyses. ER stress induced expression of ER stress factors GRP78 and BiP, cleavage of apoptotic factor PARP, and apoptosis in V and OE INS-1 cells. Ceramide accumulation during ER stress was not associated with changes in mRNA levels of serine palmitoyl-transferase (SPT), the rate-limiting enzyme in de novo synthesis of ceramides but both message and protein levels of neutral sphingomyelinase (NSMase), which hydrolyzes sphingomyelins to generate ceramides, temporally increased in the INS-1 cells. The increases in NSMase expression in the ER-stressed INS-1 cells were associated with corresponding temporal elevations in ER-associated iPLA2β protein and catalytic activity. Pretreatment with BEL inactivated iPLA2β and prevented induction of NSMase message and protein in ER-stressed INS-1 cells. Relative to V INS-1 cells, the effects of ER stress were accelerated and/or amplified in the OE INS-1 cells. However, inhibition of iPLA2β or NSMase (chemically or with siRNA) suppressed induction of NSMase message, ceramide generation, sphingomyelin hydrolysis, and apoptosis in both V and OE INS-1 cells during ER stress. In contrast, inhibition of SPT did not suppress

  6. Practical routes to (SiH₃)₃P: applications in group IV semiconductor activation and in group III-V molecular synthesis.

    PubMed

    Tice, Jesse B; Chizmeshya, A V G; Tolle, J; D' Costa, V R; Menendez, J; Kouvetakis, J

    2010-05-21

    The (SiH₃)₃P hydride is introduced as a practical source for n-doping of group IV semiconductors and as a highly-reactive delivery agent of -(SiH₃)₂P functionalities in exploratory synthesis. In contrast to earlier methods, the compound is produced here in high purity quantitative yields via a new single-step method based on reactions of SiH₃Br and (Me₃Sn)₃P, circumventing the need for toxic and unstable starting materials. As an initial demonstration of its utility we synthesized monosubstituted Me₂M-P(SiH₃)₂ (M = Al, Ga, In) derivatives of Me₃M containing the (SiH₃)₂P ligand for the first time, in analogy to the known Me₂M-P(SiMe₃)₂ counterparts. A dimeric structure of Me₂M-P(SiH₃)₂ is proposed on the basis of spectroscopic characterizations and quantum chemical simulations. Next, in the context of materials synthesis, the (SiH₃)₃P compound was used to dope germanium for the first time by building a prototype p(++)Si(100)/i-Ge/n-Ge photodiode structure. The resultant n-type Ge layers contained active carrier concentrations of 3-4 × 10¹⁹ atoms cm⁻³ as determined by spectroscopic ellipsometry and confirmed by SIMS. Strain analysis using high resolution XRD yielded a Si content of 4 × 10²⁰ atoms cm⁻³ in agreement with SIMS and within the range expected for incorporating Si₃P type units into the diamond cubic Ge matrix. Extensive characterizations for structure, morphology and crystallinity indicate that the Si co-dopant plays essentially a passive role and does not compromise the device quality of the host material nor does it fundamentally alter its optical properties.

  7. Preparation, structure, and ethylene (co)polymerization behavior of Group IV metal complexes with an [OSSO]-carborane ligand.

    PubMed

    Hu, Ping; Wang, Jian-Qiang; Wang, Fosong; Jin, Guo-Xin

    2011-07-25

    The synthesis of Group IV metal complexes that contain a tetradentate dianionic [OSSO]-carborane ligand [(HOC(6)H(2)tBu(2)-4,6)(2)(CH(2))(2)S(2)C(2 (B(10)H(10))] (1a) is described. Reactions of TiCl(4) and Ti(OiPr)(4) with the [OSSO]-type ligand 1a afford six-coordinated titanium complex [Ti(OC(6)H(2)tBu(2)-4,6)(2)(CH(2))(2)S(2)C(2)(B(10)H(10))Cl(2)] (2a) and four-coordinated titanium complex [Ti(OC(6)H(2)tBu(2)-4,6)(2)(CH(2))(2)S(2)C(2)(B(10)H(10))(OiPr)(2)] (2b), respectively. ZrCl(4) and HfCl(4) were treated with 1a to give six-coordinated zirconium complex [Zr(OC(6)H(2)tBu(2)-4,6)(2)(CH(2))(2)S(2)C(2)(B(10)H(10))Cl(2) (thf)(2)] (2c) and six-coordinated hafnium complex [Hf(OC(6)H(2)tBu(2)-4,6)(2)(CH(2))(2)S(2)C(2)(B(10)H(10))Cl(2)] (2d). All the complexes were fully characterized by IR, NMR spectroscopy, and elemental analysis. In addition, X-ray structure analyses were performed on complexes 2a and 2b and reveal the expected different coordination geometry due to steric hindrance effects. Extended X-ray absorption fine structure (EXAFS) spectroscopy was performed on complexes 2c and 2d to describe the coordination chemistry of this ligand around Zr and Hf. Six-coordinated titanium complex 2a showed good activity toward ethylene polymerization as well as toward copolymerization of ethylene with 1-hexene in the presence of methylaluminoxane (MAO) as cocatalyst (up to 1060 kg[mol(Ti)](-1) h(-1) in the case of 10 atm of ethylene pressure).

  8. Streptomyces phospholipase D cloning and production.

    PubMed

    Nakazawa, Yozo

    2012-01-01

    The transphosphatidylation catalytic ability of phospholipase D (PLD, EC 3.1.4.4) is a powerful biochemical tool for the acquisition of rare phospholipids (PLs), e.g., phosphatidylglycerol (PG) and phosphatidylserine (PS), and artificial phospholipids, which do not occur in nature. Specifically, actinomycete PLD recognizes not only the alcohols (i.e., glycerol or serine) corresponding to the polar head groups of natural PLs, but also secondary alcohols, aromatic alcohols, saccharides, N-heterocyclic alcohols, and vitamins as acceptors. Therefore, actinomycete PLD is a valuable enzyme in food, cosmetics, fine chemical and pharmaceutical industries. Here, we describe a protocol for the screening for PLD-producing microorganisms, several PLD assays and methods of PLD production-purification and the strategy of cloning of the Streptomyces PLD gene.

  9. Group IV organometallic compounds based on dianionic "pincer" ligands: synthesis, characterization, and catalytic activity in intramolecular hydroamination reactions.

    PubMed

    Luconi, Lapo; Rossin, Andrea; Motta, Alessandro; Tuci, Giulia; Giambastiani, Giuliano

    2013-04-08

    Neutral Zr(IV) and Hf(IV) diamido complexes stabilized by unsymmetrical dianionic N,C,N' pincer ligands have been prepared through the simplest and convenient direct metal-induced Caryl-H bond activation. Simple ligand modification has contributed to highlight the non-innocent role played by the donor atom set in the control of the cyclometallation kinetics. The as-prepared bis-amido catalysts were found to be good candidates for the intramolecular hydroamination/cyclization of primary aminoalkenes. The ability of these compounds to promote such a catalytic transformation efficiently (by providing, in some cases, fast and complete substrate conversion at room temperature) constitutes a remarkable step forward toward catalytic systems that can operate at relatively low catalyst loading and under milder reaction conditions. Kinetic studies and substrate-scope investigations, in conjunction with preliminary DFT calculations on the real systems, were used to elucidate the effects of the substrate substitution on the catalyst performance and to support the most reliable mechanistic path operative in the hydroamination reaction.

  10. Autoproteolytic Activation of a Symbiosis-regulated Truffle Phospholipase A2.

    PubMed

    Cavazzini, Davide; Meschi, Francesca; Corsini, Romina; Bolchi, Angelo; Rossi, Gian Luigi; Einsle, Oliver; Ottonello, Simone

    2013-01-18

    Fungal phospholipases are members of the fungal/bacterial group XIV secreted phospholipases A(2) (sPLA(2)s). TbSP1, the sPLA(2) primarily addressed in this study, is up-regulated by nutrient deprivation and is preferentially expressed in the symbiotic stage of the ectomycorrhizal fungus Tuber borchii. A peculiar feature of this phospholipase and of its ortholog from the black truffle Tuber melanosporum is the presence of a 54-amino acid sequence of unknown functional significance, interposed between the signal peptide and the start of the conserved catalytic core of the enzyme. X-ray diffraction analysis of a recombinant TbSP1 form corresponding to the secreted protein previously identified in T. borchii mycelia revealed a structure comprising the five α-helices that form the phospholipase catalytic module but lacking the N-terminal 54 amino acids. This finding led to a series of functional studies that showed that TbSP1, as well as its T. melanosporum ortholog, is a self-processing pro-phospholipase A(2), whose phospholipase activity increases up to 80-fold following autoproteolytic removal of the N-terminal peptide. Proteolytic cleavage occurs within a serine-rich, intrinsically flexible region of TbSP1, does not involve the phospholipase active site, and proceeds via an intermolecular mechanism. Autoproteolytic activation, which also takes place at the surface of nutrient-starved, sPLA(2) overexpressing hyphae, may strengthen and further control the effects of phospholipase up-regulation in response to nutrient deprivation, also in the context of symbiosis establishment and mycorrhiza formation.

  11. Autoproteolytic Activation of a Symbiosis-regulated Truffle Phospholipase A2*

    PubMed Central

    Cavazzini, Davide; Meschi, Francesca; Corsini, Romina; Bolchi, Angelo; Rossi, Gian Luigi; Einsle, Oliver; Ottonello, Simone

    2013-01-01

    Fungal phospholipases are members of the fungal/bacterial group XIV secreted phospholipases A2 (sPLA2s). TbSP1, the sPLA2 primarily addressed in this study, is up-regulated by nutrient deprivation and is preferentially expressed in the symbiotic stage of the ectomycorrhizal fungus Tuber borchii. A peculiar feature of this phospholipase and of its ortholog from the black truffle Tuber melanosporum is the presence of a 54-amino acid sequence of unknown functional significance, interposed between the signal peptide and the start of the conserved catalytic core of the enzyme. X-ray diffraction analysis of a recombinant TbSP1 form corresponding to the secreted protein previously identified in T. borchii mycelia revealed a structure comprising the five α-helices that form the phospholipase catalytic module but lacking the N-terminal 54 amino acids. This finding led to a series of functional studies that showed that TbSP1, as well as its T. melanosporum ortholog, is a self-processing pro-phospholipase A2, whose phospholipase activity increases up to 80-fold following autoproteolytic removal of the N-terminal peptide. Proteolytic cleavage occurs within a serine-rich, intrinsically flexible region of TbSP1, does not involve the phospholipase active site, and proceeds via an intermolecular mechanism. Autoproteolytic activation, which also takes place at the surface of nutrient-starved, sPLA2 overexpressing hyphae, may strengthen and further control the effects of phospholipase up-regulation in response to nutrient deprivation, also in the context of symbiosis establishment and mycorrhiza formation. PMID:23192346

  12. Compounds of tin(IV) - catalysts of amide formation. Effect of temperature and nature of leaving group

    SciTech Connect

    Oleinik, N.M.; Garkusha-Bozhko, I.P.; Usanova, I.V.

    1988-09-20

    The effect of substitution of the ester oxygen atom by sulfur in p-nitrophenyl acetate on its aminolysis rate with benzylamine in beneze at 25/degree/C in the presence of dibutyltin dibenzoate as catalyst was studied. Such substitution leads to a decrease in the catalytic activity by approximately a half, and this is explained by the smaller capacity of the sulfur atom for the formation of hydrogen bonds. The effect of temperature on the rate of the reaction of N-benzyl-oxycarbonylglycine p-nitrophenyl ester with glycine tert-butyl ester in benzene in the presence of dibutyltin dibenzoate was also investigated in the range of 10-50/degree/C. The Arrhenius equation is not fulfilled in this case. The obtained facts demonstrate the multistage character of the catalytic reaction and do not contradict the authors previously proposed bifunctional mechanism of catalysis by tin(IV) compounds.

  13. Sublattice enumeration. IV. Equivalence classes of plane sublattices by parent Patterson symmetry and colour lattice group type.

    PubMed

    Rutherford, John S

    2009-03-01

    The Dirichlet generating functions for the number of sublattices fixed under each symmetry operation of the parent Patterson group may be combined to count the number of crystallographically nonequivalent sublattices, in total, by sublattice point group and by colour lattice group type. The combinatorial formulae used imply the existence of various congruences among the corresponding arithmetic functions.

  14. STUDIES IN THE BLOOD CYTOLOGY OF THE RABBIT : IV. CONSECUTIVE NEUTROPHILE, BASOPHILE, AND EOSINOPHILE OBSERVATIONS ON GROUPS OF NORMAL RABBITS.

    PubMed

    Pearce, L; Casey, A E

    1930-07-31

    Consecutive weekly observations on the neutrophile, the basophile, and the eosinophile counts of the peripheral blood were made on 5 groups of normal rabbits, a total of 45 animals, during a period of 20 months from October, 1927 to July, 1929. Individual groups were examined 8 to 35 weeks. In the case of the 4 groups followed 13 to 35 weeks, the general trend of the neutrophile cells was towards increased mean values; with the group followed 8 weeks, decreasing values were found. An increase in the mean values of the basophile cells was observed in the two groups of rabbits followed in 1927-28; in the groups of 1928-29, the mean values decreased. The mean values of the eosinophile cells showed no definite trends but the findings were characterized by abrupt and marked fluctuations. The periods of greatest irregularity in mean neutrophile and eosinophile values occurred in the fall and the late winter and spring months of both years, but in the case of the basophiles, the irregularities were distributed throughout the first year and occurred chiefly in the winter months of the second year. The major trends and many of the minor fluctuations as well which were observed in the mean cell values of one group of rabbits were also generally seen in another group examined during the same months. The general levels of the neutrophile, the basophile, and the eosinophile mean values in the groups examined during 1927-28 were higher than in the groups of 1928-29.

  15. Effect of charge transfer on the local order in liquid group IV isoelectronic compounds: neutron diffraction data versus numerical tight-binding simulations

    SciTech Connect

    Prigent, G.; Bellissent, R.; Gaspard, J.-P.; Bichara, C.

    1999-06-15

    In a simple tight-binding approach, we consider the role of charge transfer and entropy in the semiconductor-to-metal transition which may occur upon melting group IV elements and their isoelectronic III-V and II-VI compounds. In the liquid state, entropy is shown to destabilise the diamond structure in favor of a metallic simple cubic-like local order, while charge transfer tends to keep the semiconducting tetrahedral local order of the solid state. These results are consistent with neutron diffraction data.

  16. Lipase and phospholipase biosensors: a review.

    PubMed

    Herrera-López, Enrique J

    2012-01-01

    Recent advances in the field of biology, electronics, and nanotechnology have improved the development of biosensors. A biosensor is a device composed of a biological recognition element and a sensor element. Biosensor applications are becoming increasingly important in areas such as biotechnology, pharmaceutics, food, and environment. Lipases and phospholipases are enzymes which have been used widely in food industry, oleochemical industry, biodegradable polymers, detergents, and other applications. In the medical industry, lipases and phospholipases are used as diagnostic tools to detect triglycerides, cholesterol, and phospholipids levels in blood samples. Therefore, the development of lipase and phospholipase biosensors is of paramount importance in the clinical area. This chapter introduces the reader into the preliminaries of biosensor and reviews recent developments of lipase and phospholipase biosensors.

  17. The Architectural Chromatin Factor High Mobility Group A1 Enhances DNA Ligase IV Activity Influencing DNA Repair

    PubMed Central

    Costantini, Silvia; Pegoraro, Silvia; Ros, Gloria; Penzo, Carlotta; Triolo, Gianluca; Demarchi, Francesca; Sgarra, Riccardo; Vindigni, Alessandro; Manfioletti, Guidalberto

    2016-01-01

    The HMGA1 architectural transcription factor is an oncogene overexpressed in the vast majority of human cancers. HMGA1 is a highly connected node in the nuclear molecular network and the key aspect of HMGA1 involvement in cancer development is that HMGA1 simultaneously confers cells multiple oncogenic hits, ranging from global chromatin structural and gene expression modifications up to the direct functional alterations of key cellular proteins. Interestingly, HMGA1 also modulates DNA damage repair pathways. In this work, we provide evidences linking HMGA1 with Non-Homologous End Joining DNA repair. We show that HMGA1 is in complex with and is a substrate for DNA-PK. HMGA1 enhances Ligase IV activity and it counteracts the repressive histone H1 activity towards DNA ends ligation. Moreover, breast cancer cells overexpressing HMGA1 show a faster recovery upon induction of DNA double-strand breaks, which is associated with a higher survival. These data suggest that resistance to DNA-damaging agents in cancer cells could be partially attributed to HMGA1 overexpression thus highlighting the relevance of considering HMGA1 expression levels in the selection of valuable and effective pharmacological regimens. PMID:27723831

  18. The Architectural Chromatin Factor High Mobility Group A1 Enhances DNA Ligase IV Activity Influencing DNA Repair.

    PubMed

    Pellarin, Ilenia; Arnoldo, Laura; Costantini, Silvia; Pegoraro, Silvia; Ros, Gloria; Penzo, Carlotta; Triolo, Gianluca; Demarchi, Francesca; Sgarra, Riccardo; Vindigni, Alessandro; Manfioletti, Guidalberto

    2016-01-01

    The HMGA1 architectural transcription factor is an oncogene overexpressed in the vast majority of human cancers. HMGA1 is a highly connected node in the nuclear molecular network and the key aspect of HMGA1 involvement in cancer development is that HMGA1 simultaneously confers cells multiple oncogenic hits, ranging from global chromatin structural and gene expression modifications up to the direct functional alterations of key cellular proteins. Interestingly, HMGA1 also modulates DNA damage repair pathways. In this work, we provide evidences linking HMGA1 with Non-Homologous End Joining DNA repair. We show that HMGA1 is in complex with and is a substrate for DNA-PK. HMGA1 enhances Ligase IV activity and it counteracts the repressive histone H1 activity towards DNA ends ligation. Moreover, breast cancer cells overexpressing HMGA1 show a faster recovery upon induction of DNA double-strand breaks, which is associated with a higher survival. These data suggest that resistance to DNA-damaging agents in cancer cells could be partially attributed to HMGA1 overexpression thus highlighting the relevance of considering HMGA1 expression levels in the selection of valuable and effective pharmacological regimens.

  19. Secreted phospholipase A2 and mast cells.

    PubMed

    Murakami, Makoto; Taketomi, Yoshitaka

    2015-01-01

    Phospholipase A2s (PLA2s) are a group of enzymes that hydrolyze the sn-2 position of phospholipids to release (typically unsaturated) fatty acids and lysophospholipids, which serve as precursors for a variety of bioactive lipid mediators. Among the PLA2 superfamily, secreted PLA2 (sPLA2) enzymes comprise the largest subfamily that includes 11 isoforms with a conserved His-Asp catalytic dyad. Individual sPLA2 enzymes exhibit unique tissue and cellular localizations and specific enzymatic properties, suggesting their distinct biological roles. Recent studies using transgenic and knockout mice for individual sPLA2 isofoms have revealed their involvement in various pathophysiological events. Here, we overview the current state of knowledge about sPLA2s, specifically their roles in mast cells (MCs) in the context of allergology. In particular, we highlight group III sPLA2 (PLA2G3) as an "anaphylactic sPLA2" that promotes MC maturation and thereby anaphylaxis through a previously unrecognized lipid-orchestrated circuit.

  20. Developmental decline in modulation of glutamatergic synapses in layer IV of the barrel cortex by group II metabotropic glutamate receptors.

    PubMed

    Mateo, Z; Porter, J T

    2015-04-02

    Previously, we demonstrated that group II metabotropic glutamate receptors (mGluRs) reduce glutamate release from thalamocortical synapses during early postnatal development (P7-11). To further examine the role of group II mGluRs in the modulation of somatosensory circuitry, we determined whether group II mGluRs continue to modulate thalamocortical synapses until adulthood and whether these receptors also modulate intra-cortical synapses in the barrel cortex. To address these issues, we examined the effect of the group II mGluR agonists on thalamocortical excitatory postsynaptic currents (EPSCs) and intra-barrel EPSCs in slices from animals of different ages (P7-53). We found that the depression of thalamocortical EPSCs by group II mGluRs rapidly declined after the second postnatal week. In contrast, adenosine continued to depress thalamocortical EPSCs via a presynaptic mechanism in young adult mice (P30-50). Activation of group II mGluRs also reduced intra-barrel EPSCs through a postsynaptic mechanism in young mice (P7-11). Similar to the thalamocortical synapses, the group II mGluR modulation of intra-barrel excitatory synapses declined with development. In young adult animals (P30-50), group II mGluR stimulation had little effect on intra-barrel EPSCs but did hyperpolarize the neurons. Together our results demonstrate that group II mGluRs modulate barrel cortex circuitry by presynaptic and postsynaptic mechanisms depending on the source of the synapse and that this modulation declines with development.

  1. Lattice Thermal Conductivity of the Binary and Ternary Group-IV Alloys Si-Sn, Ge-Sn, and Si-Ge-Sn

    NASA Astrophysics Data System (ADS)

    Khatami, S. N.; Aksamija, Z.

    2016-07-01

    Efficient thermoelectric (TE) energy conversion requires materials with low thermal conductivity and good electronic properties. Si-Ge alloys, and their nanostructures such as thin films and nanowires, have been extensively studied for TE applications; other group-IV alloys, including those containing Sn, have not been given as much attention as TEs, despite their increasing applications in other areas including optoelectronics. We study the lattice thermal conductivity of binary (Si-Sn and Ge-Sn) and ternary (Si-Ge-Sn) alloys and their thin films in the Boltzmann transport formalisms, including a full phonon dispersion and momentum-dependent boundary-roughness scattering. We show that Si-Sn alloys have the lowest conductivity (3 W /mK ) of all the bulk alloys, more than 2 times lower than Si-Ge, attributed to the larger difference in mass between the two constituents. In addition, we demonstrate that thin films offer an additional reduction in thermal conductivity, reaching around 1 W /mK in 20-nm-thick Si-Sn, Ge-Sn, and ternary Si-Ge-Sn films, which is near the conductivity of amorphous SiO2 . We conclude that group-IV alloys containing Sn have the potential for high-efficiency TE energy conversion.

  2. “Structural Transformations in Ceramics: Perovskite-like Oxides and Group III, IV, and V Nitrides”

    SciTech Connect

    James P. Lewis , Dorian M. Hatch , and Harold T. Stokes

    2006-12-31

    1 Overview of Results and their Significance Ceramic perovskite-like oxides with the general formula (A. A0. ...)(B. B0. ...)O3and titanium-based oxides are of great technological interest because of their large piezoelectric and dielectric response characteristics.[1] In doped and nanoengineered forms, titantium dioxide finds increasing application as an organic and hydrolytic photocatalyst. The binary main-group-metal nitride compounds have undergone recent advancements of in-situ heating technology in diamond anvil cells leading to a burst of experimental and theoretical interest. In our DOE proposal, we discussed our unique theoretical approach which applies ab initio electronic calculations in conjunction with systematic group-theoretical analysis of lattice distortions to study two representative phase transitions in ceramic materials: (1) displacive phase transitions in primarily titanium-based perovskite-like oxide ceramics, and (2) reconstructive phase transitions in main-group nitride ceramics. A sub area which we have explored in depth is doped titanium dioxide electrical/optical properties.

  3. Mutual passivation of group IV donors and isovalent nitrogen in diluted GaN{sub x}As{sub 1-x} alloys

    SciTech Connect

    Yu, K.M.; Wu, J.; Walukiewicz, W.; Shan, W.; Beeman, J.; Mars, D.E.; Chamberlin, D.R.; Scarpulla, M.A.; Dubon, O.D.; Ridgway, M.C.; Geisz, J.F.

    2003-07-23

    We demonstrate the mutual passivation of electrically active group IV donors and isovalent N atoms in the GaN{sub x}As{sub 1-x} alloy system. This phenomenon occurs through the formation of a donor-nitrogen bond in the nearest neighbor IV{sub Ga}-N{sub As} pairs. In Si doped GaInN{sub 0.017}As{sub 0.983} the electron concentration starts to decrease rapidly at an annealing temperature of 700 C from {approx} 3 x 10{sup 19}cm{sup -3} in the as-grown state to less than 10{sup 16}cm{sup -3} after an annealing at 900 C for 10 s. At the same time annealing of this sample at 950 C increases the gap by about 35 meV, corresponding to a reduction of the concentration of the active N atoms by an amount very close to the total Si concentration. We also show that the formation of Si{sub Ga}-N{sub As} pairs is controlled by the diffusion of Si via Ga vacancies to the nearest N{sub As} site. The general nature of this mutual passivation effect is confirmed by our study of Ge doped GaN{sub x}As{sub 1-x} layers formed by N and Ge co-implantation in GaAs followed by pulsed laser melting.

  4. Population studies in groups and clusters of galaxies. IV - Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    NASA Technical Reports Server (NTRS)

    Ferguson, Henry C.; Sandage, Allan

    1991-01-01

    Published observational data on the Leo, Dorado, NGC 1400, NGC 5044, Antlia, Fornax, and Virgo groups of galaxies are analyzed in terms of the luminosity functions and morphological types of their members. The data sets employed are characterized, and the results are presented in extensive tables and graphs and discussed in detail. While the fractions of early and late galaxies in the groups are similar, the ratio of dwarfs to giants (D/G) in the early galaxies varies monotonically with the richness of the cluster, leading to artificial flattening at the faint end of the total luminosity function in environments with low D/G. The luminosity function for dwarfs in all environments is found to have a slope of about -1.3.

  5. Population studies in groups and clusters of galaxies. IV. Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    SciTech Connect

    Ferguson, H.C.; Sandage, A. Observatories of the Carnegie Institution, Pasadena, CA Space Telescope Science Institute, Baltimore, MD )

    1991-03-01

    Published observational data on the Leo, Dorado, NGC 1400, NGC 5044, Antlia, Fornax, and Virgo groups of galaxies are analyzed in terms of the luminosity functions and morphological types of their members. The data sets employed are characterized, and the results are presented in extensive tables and graphs and discussed in detail. While the fractions of early and late galaxies in the groups are similar, the ratio of dwarfs to giants (D/G) in the early galaxies varies monotonically with the richness of the cluster, leading to artificial flattening at the faint end of the total luminosity function in environments with low D/G. The luminosity function for dwarfs in all environments is found to have a slope of about -1.3. 54 refs.

  6. Nomenclatural Studies Toward a World List of Diptera Genus-Group Names. Part IV: Charles Henry Tyler Townsend.

    PubMed

    Evenhuis, Neal L; Pont, Adrian C; Whitmore, Daniel

    2015-06-25

    The Diptera genus-group names of Charles Henry Tyler Townsend are reviewed and annotated. A total of 1506 available genus-group names in 12 families of Diptera are listed alphabetically for each name, giving author, year and page of original publication, originally included species, type species and method of fixation, current status of the name, family placement, and a list of any emendations of it that have been found in the literature. Remarks are given to clarify nomenclatural and/or taxonomic information. In addition, an index to all the species-group names of Diptera proposed by Townsend (1595, of which 1574 are available names) is given with bibliographic reference (year and page) to each original citation. An appendix with a full bibliography of almost 650 papers written by Townsend is presented with accurate dates of publication.        Two new replacement names are proposed for preoccupied genus-group names and both are named to honor our good friend and colleague, James E. O'Hara, for his decades of work on tachinids: Oharamyia Evenhuis, Pont & Whitmore, n. name, for Lindigia Townsend, 1931 [Tachinidae] (preoccupied by Karsten, 1858); Jimimyia Evenhuis, Pont & Whitmore, n. name, for Siphonopsis Townsend, 1916 [Tachinidae] (preoccupied by Agassiz, 1846).        Earlier dates of availability are found for the following: Eucnephalia Townsend, 1892 [Tachinidae]; Gabanimyia Townsend, 1914 [Tachinidae]; Incamyia Townsend, 1912 [Tachinidae]; Muscopteryx Townsend, 1892 [Tachinidae]; Philippolophosia Townsend, 1927 [Tachinidae]; Pseudokea Townsend, 1927 [Tachinidae].        Corrected or clarified included species and/or corrected or clarified type-species and methods of typification are given for: Alitophasia Townsend, 1934 [Tachinidae]; Almugmyia Townsend, 1911 [Tachinidae]; Arachnidomyia Townsend, 1934 [Sarcophagidae]; Austenina Townsend, 1921 [Glossinidae]; Austrohartigia Townsend, 1937 [Sarcophagidae]; Awatia Townsend, 1921 [Muscidae

  7. All-electron molecular Dirac-Hartree-Fock calculations - Properties of the group IV monoxides GeO, SnO, and PbO

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.

    1993-01-01

    Dirac-Hartree-Fock calculations have been carried out on the ground states of the group IV monoxides GeO, SnO and PbO. Geometries, dipole moments and infrared data are presented. For comparison, nonrelativistic, first-order perturbation and relativistic effective core potential calculations have also been carried out. Where appropriate the results are compared with the experimental data and previous calculations. Spin-orbit effects are of great importance for PbO, where first-order perturbation theory including only the mass-velocity and Darwin terms is inadequate to predict the relativistic corrections to the properties. The relativistic effective core potential results show a larger deviation from the all-electron values than for the hydrides, and confirm the conclusions drawn on the basis of the hydride calculations.

  8. All-electron molecular Dirac-Hartree-Fock calculations: Properties of the group IV monoxides GeO, SnO and PbO

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.

    1991-01-01

    Dirac-Hartree-Fock calculations have been carried out on the ground states of the group IV monoxides GeO, SnO and PbO. Geometries, dipole moments and infrared data are presented. For comparison, nonrelativistic, first-order perturbation and relativistic effective core potential calculations have also been carried out. Where appropriate the results are compared with the experimental data and previous calculations. Spin-orbit effects are of great importance for PbO, where first-order perturbation theory including only the mass-velocity and Darwin terms is inadequate to predict the relativistic corrections to the properties. The relativistic effective core potential results show a larger deviation from the all-electron values than for the hydrides, and confirm the conclusions drawn on the basis of the hydride calculations.

  9. THE ACS LCID PROJECT. IV. DETECTION OF THE RED GIANT BRANCH BUMP IN ISOLATED GALAXIES OF THE LOCAL GROUP

    SciTech Connect

    Monelli, M.; Hidalgo, S. L; Aparicio, A.; Gallart, C.; Cassisi, S.; Bernard, E. J.; Skillman, E. D. E-mail: carme@iac.e E-mail: shidalgo@iac.e E-mail: ejb@roe.ac.u

    2010-08-01

    We report the detection and analysis of the red giant branch (RGB) luminosity function bump in a sample of isolated dwarf galaxies in the Local Group. We have designed a new analysis approach comparing the observed color-magnitude diagrams (CMDs) with theoretical best-fit CMDs derived from precise estimates of the star formation histories of each galaxy. This analysis is based on studying the difference between the V magnitude of the RGB bump and the horizontal branch at the level of the RR Lyrae instability strip ({Delta}V {sup bump}{sub HB}) and we discuss here a technique for reliably measuring this quantity in complex stellar systems. By using this approach, we find that the difference between the observed and predicted values of {Delta}V {sup bump}{sub HB} is +0.13 {+-} 0.14 mag. This is smaller, by about a factor of 2, than the well-known discrepancy between theory and observation at low metallicity commonly derived for Galactic globular clusters (GCs). This result is confirmed by a comparison between the adopted theoretical framework and empirical estimates of the {Delta}V {sup bump}{sub HB} parameter for both a large database of Galactic GCs and for four other dwarf spheroidal galaxies for which this estimate is available in the literature. We also investigate the strength of the RGB bump feature (R{sub bump}), and find very good agreement between the observed and theoretically predicted R{sub bump} values. This agreement supports the reliability of the evolutionary lifetimes predicted by theoretical models of the evolution of low-mass stars.

  10. Preliminary crystallographic study of an acidic phospholipase A2 from Ophiophagus hannah (king cobra).

    PubMed

    Xu, Sujuan; Gu, Lichuan; Wang, Qiuyan; Shu, Yuyan; Lin, Zhengjiong

    2002-10-01

    An acidic phospholipase A(2) (OH APLA(2)-II) with an isoelectric point (pI) of 4.0 was recently isolated from Ophiophagus hannah (king cobra) from Guangxi province, China. Comparison of this enzyme to a previously reported homologous phospholipase A(2) from the same venom shows that it lacks toxicity and exhibits a greater phospholipase activity. OH APLA(2)-II has been crystallized by the hanging-drop vapour-diffusion method using 1,6-hexanediol and magnesium chloride as precipitants. The crystal belongs to space group P6(3), with unit-cell parameters a = b = 98.06, c = 132.39 A. The diffraction data were collected under cryoconditions (100 K) and reduced to 2.1 A resolution. A molecular-replacement solution has been determined and shows that there are six molecules in one asymmetric unit.

  11. Phospholipases in food industry: a review.

    PubMed

    Casado, Víctor; Martín, Diana; Torres, Carlos; Reglero, Guillermo

    2012-01-01

    Mammal, plant, and mainly microbial phospholipases are continuously being studied, experimented, and some of them are even commercially available at industrial scale for food industry. This is because the use of phospholipases in the production of specific foods leads to attractive advantages, such as yield improvement, energy saving, higher efficiency, improved properties, or better quality of the final product. Furthermore, biocatalysis approaches in the food industry are of current interest as non-pollutant and cleaner technologies. The present chapter reviews the most representative examples of the use of phospholipases in food industry, namely edible oils, dairy, and baking products, emulsifying agents, as well as the current trend to the development of novel molecular species of phospholipids with added-value characteristics.

  12. [Several properties of cotton seed phospholipase D].

    PubMed

    Rakhimov, M M; Mad'iarov, Sh R; Abdumalikov, A Kh

    1976-03-01

    Properties of phospholipase D were studied using purified enzyme preparation from cotton seeds. The results obtained differ from those described in literature. It has been shown that the promoting action is exerted not only by diethyl ether and sodium dodecyl sulfate commonly used as initiators, but by some organic solvents in the presence of calcium ions as well. The activation of phospholipase D is also possible in the presence of other bivalent cations, e.g. Sr2+, Ba2+, Mn2+ and Mg2+. It is assumed that the enzyme activation occurs only in the presence of the stable heterogenous system: water-soluble enzyme--phospholipid--non-aqueous phase. Another important factor is the type of modification of the surface of the phospholipid phase, responsible for the enzyme adsorption and its subsequent activation. Comparison is made of the properties of phospholipases D isolated from cotton seeds and some other sources.

  13. Methylmercury-induced toxicity is mediated by enhanced intracellular calcium through activation of phosphatidylcholine-specific phospholipase C

    SciTech Connect

    Kang, Mi Sun; Jeong, Ju Yeon; Seo, Ji Heui; Jeon, Hyung Jun; Jung, Kwang Mook; Chin, Mi-Reyoung; Moon, Chang-Kiu; Bonventre, Joseph V.; Jung, Sung Yun; Kim, Dae Kyong . E-mail: proteinlab@hanmail.net

    2006-10-15

    Methylmercury (MeHg) is a ubiquitous environmental toxicant to which humans can be exposed by ingestion of contaminated food. MeHg has been suggested to exert its toxicity through its high reactivity to thiols, generation of arachidonic acid and reactive oxygen species (ROS), and elevation of free intracellular Ca{sup 2+} levels ([Ca{sup 2+}]{sub i}). However, the precise mechanism has not been fully defined. Here we show that phosphatidylcholine-specific phospholipase C (PC-PLC) is a critical pathway for MeHg-induced toxicity in MDCK cells. D609, an inhibitor of PC-PLC, significantly reversed the toxicity in a time- and dose-dependent manner with concomitant inhibition of the diacylglycerol (DAG) generation and the phosphatidylcholine (PC)-breakdown. MeHg activated the group IV cytosolic phospholipase A{sub 2} (cPLA{sub 2}) and acidic form of sphingomyelinase (A-SMase) downstream of PC-PLC, but these enzymes as well as protein kinase C (PKC) were not linked to the toxicity by MeHg. Furthermore, MeHg produced ROS, which did not affect the toxicity. Addition of EGTA to culture media resulted in partial decrease of [Ca{sup 2+}]{sub i} and partially blocked the toxicity. In contrast, when the cells were treated with MeHg in the presence of Ca{sup 2+} in the culture media, D609 completely prevented cell death with parallel decrease in [Ca{sup 2+}]{sub i}. Our results demonstrated that MeHg-induced toxicity was linked to elevation of [Ca{sup 2+}]{sub i} through activation of PC-PLC, but not attributable to the signaling pathways such as cPLA{sub 2}, A-SMase, and PKC, or to the generation of ROS.

  14. Group-IV midinfrared plasmonics

    NASA Astrophysics Data System (ADS)

    Biagioni, Paolo; Frigerio, Jacopo; Samarelli, Antonio; Gallacher, Kevin; Baldassarre, Leonetta; Sakat, Emilie; Calandrini, Eugenio; Millar, Ross W.; Giliberti, Valeria; Isella, Giovanni; Paul, Douglas J.; Ortolani, Michele

    2015-01-01

    The use of heavily doped semiconductors to achieve plasma frequencies in the mid-IR has been recently proposed as a promising way to obtain high-quality and tunable plasmonic materials. We introduce a plasmonic platform based on epitaxial n-type Ge grown on standard Si wafers by means of low-energy plasma-enhanced chemical vapor deposition. Due to the large carrier concentration achieved with P dopants and to the compatibility with the existing CMOS technology, SiGe plasmonics hold promises for mid-IR applications in optoelectronics, IR detection, sensing, and light harvesting. As a representative example, we show simulations of mid-IR plasmonic waveguides based on the experimentally retrieved dielectric constants of the grown materials.

  15. Phospholipases A2 and Inflammatory Responses in the Central Nervous System

    PubMed Central

    Sun, Grace Y.; Shelat, Phullara B.; Jensen, Michael B.; He, Yan; Sun, Albert Y.; Simonyi, Agnes

    2011-01-01

    Phospholipases A2 (PLA2s) belong to a superfamily of enzymes responsible for hydrolyzing the sn-2 fatty acids of membrane phospholipids. These enzymes are known to play multiple roles for maintenance of membrane phospholipid homeostasis and for production of a variety of lipid mediators. Over 20 different types of PLA2s are present in the mammalian cells, and in snake and bee venom. Despite their common function in hydrolyzing fatty acids of phospholipids, they are diversely encoded by a number of genes and express proteins that are regulated by different mechanisms. Recent studies have focused on the group IV calcium-dependent cytosolic cPLA2, the group VI calcium-independent iPLA2, and the group II small molecule secretory sPLA2. In the central nervous system (CNS), these PLA2s are distributed among neurons and glial cells. Although the physiological role of these PLA2s in regulating neural cell function has not yet been clearly elucidated, there is increasing evidence for their involvement in receptor signaling and transcriptional pathways that link oxidative events to inflammatory responses that underline many neurodegenerative diseases. Recent studies also reveal an important role of cPLA2 in modulating neuronal excitatory functions, sPLA2 in the inflammatory responses, and iPLA2 with childhood neurologic disorders associated with brain iron accumulation. The goal for this review is to better understand the structure and function of these PLA2s and to highlight specific types of PLA2s and their cross-talk mechanisms in these inflammatory responses under physiological and pathological conditions in the CNS. PMID:19855947

  16. Cytosolic phospholipase A2α regulates G1 progression through modulating FOXO1 activity

    PubMed Central

    Naini, Said Movahedi; Choukroun, Gabriel J.; Ryan, James R.; Hentschel, Dirk M.; Shah, Jagesh V.; Bonventre, Joseph V.

    2016-01-01

    Group IVA phospholipase A2 [cytosolic phospholipase A2α (cPLA2α)] is a key mediator of inflammation and tumorigenesis. In this study, by using a combination of chemical inhibition and genetic approaches in zebrafish and murine cells, we identify a mechanism by which cPLA2α promotes cell proliferation. We identified 2 cpla2α genes in zebrafish, cpla2αa and cpla2αb, with conserved phospholipase activity. In zebrafish, loss of cpla2α expression or inhibition of cpla2α activity diminished G1 progression through the cell cycle. This phenotype was also seen in both mouse embryonic fibroblasts and mesangial cells. G1 progression was rescued by the addition of arachidonic acid or prostaglandin E2 (PGE2), indicating a phospholipase-dependent mechanism. We further show that PGE2, through PI3K/AKT activation, promoted Forkhead box protein O1 (FOXO1) phosphorylation and FOXO1 nuclear export. This led to up-regulation of cyclin D1 and down-regulation of p27Kip1, thus promoting G1 progression. Finally, using pharmacologic inhibitors, we show that cPLA2α, rapidly accelerated fibrosarcoma (RAF)/MEK/ERK, and PI3K/AKT signaling pathways cooperatively regulate G1 progression in response to platelet-derived growth factor stimulation. In summary, these data indicate that cPLA2α, through its phospholipase activity, is a critical effector of G1 phase progression through the cell cycle and suggest that pharmacological targeting of this enzyme may have important therapeutic benefits in disease mechanisms that involve excessive cell proliferation, in particular, cancer and proliferative glomerulopathies.—Naini, S. M., Choukroun, G. J., Ryan, J. R., Hentschel, D. M., Shah, J. V., Bonventre, J. V. Cytosolic phospholipase A2α regulates G1 progression through modulating FOXO1 activity. PMID:26644349

  17. Secretion of phospholipase C by Pseudomonas aeruginosa.

    PubMed Central

    Stinson, M W; Hayden, C

    1979-01-01

    The conditions necessary for the secretion of phospholipase C (phosphatidylcholine cholinephosphohydrolase) by Pseudomonas aeruginosa were studied. Enzyme secretion by washed cell suspensions required a carbon source and ammonium, potassium, and calcium ions. The calcium requirement could be substituted by magnesium and strontium but not by copper, manganese, cobalt, or zinc. During growth in liquid medium, cells secreted phospholipase C during late logarithmic and early stationary phases. Secretion was repressed by the addition of inorganic phosphate but not by organic phosphates, glucose, or sodium succinate. Studies with tetracycline indicated that de novo protein synthesis was necessary for the secretion of phospholipase C and that the exoenzyme was not released from a preformed periplasmic pool. Similarly, extraction of actively secreting cells with 0.2 M MgCl2 at pH 8.4 solubilized large quantities of the periplasmic enzyme alkaline phosphatase but insignificant amounts of phospholipase C. Bacteria continued to secrete enzyme for nearly 45 min after the addition of inorganic phosphate or rifampin. Images PMID:114487

  18. The 10/66 Dementia Research Group's fully operationalised DSM-IV dementia computerized diagnostic algorithm, compared with the 10/66 dementia algorithm and a clinician diagnosis: a population validation study

    PubMed Central

    Prince, Martin J; de Rodriguez, Juan Llibre; Noriega, L; Lopez, A; Acosta, Daisy; Albanese, Emiliano; Arizaga, Raul; Copeland, John RM; Dewey, Michael; Ferri, Cleusa P; Guerra, Mariella; Huang, Yueqin; Jacob, KS; Krishnamoorthy, ES; McKeigue, Paul; Sousa, Renata; Stewart, Robert J; Salas, Aquiles; Sosa, Ana Luisa; Uwakwa, Richard

    2008-01-01

    Background The criterion for dementia implicit in DSM-IV is widely used in research but not fully operationalised. The 10/66 Dementia Research Group sought to do this using assessments from their one phase dementia diagnostic research interview, and to validate the resulting algorithm in a population-based study in Cuba. Methods The criterion was operationalised as a computerised algorithm, applying clinical principles, based upon the 10/66 cognitive tests, clinical interview and informant reports; the Community Screening Instrument for Dementia, the CERAD 10 word list learning and animal naming tests, the Geriatric Mental State, and the History and Aetiology Schedule – Dementia Diagnosis and Subtype. This was validated in Cuba against a local clinician DSM-IV diagnosis and the 10/66 dementia diagnosis (originally calibrated probabilistically against clinician DSM-IV diagnoses in the 10/66 pilot study). Results The DSM-IV sub-criteria were plausibly distributed among clinically diagnosed dementia cases and controls. The clinician diagnoses agreed better with 10/66 dementia diagnosis than with the more conservative computerized DSM-IV algorithm. The DSM-IV algorithm was particularly likely to miss less severe dementia cases. Those with a 10/66 dementia diagnosis who did not meet the DSM-IV criterion were less cognitively and functionally impaired compared with the DSMIV confirmed cases, but still grossly impaired compared with those free of dementia. Conclusion The DSM-IV criterion, strictly applied, defines a narrow category of unambiguous dementia characterized by marked impairment. It may be specific but incompletely sensitive to clinically relevant cases. The 10/66 dementia diagnosis defines a broader category that may be more sensitive, identifying genuine cases beyond those defined by our DSM-IV algorithm, with relevance to the estimation of the population burden of this disorder. PMID:18577205

  19. Tretinoin Nanogel 0.025% Versus Conventional Gel 0.025% in Patients with Acne Vulgaris: A Randomized, Active Controlled, Multicentre, Parallel Group, Phase IV Clinical Trial

    PubMed Central

    Chandrashekhar, B S; Anitha, M.; Ruparelia, Mukesh; Vaidya, Pradyumna; Aamir, Riyaz; Shah, Sunil; Thilak, S; Aurangabadkar, Sanjeev; Pal, Sandeep; Saraswat, Abir

    2015-01-01

    Background: Conventional topical tretinoin formulation is often associated with local adverse events. Nanogel formulation of tretinoin has good physical stability and enables good penetration of tretinoin into the pilo-sebaceous glands. Aim: The present study was conducted to assess the efficacy and safety of a nanogel formulation of tretinoin as compared to its conventional gel formulation in the treatment of acne vulgaris of the face. Materials and Methods: This randomized, active controlled, multicentric, phase IV clinical trial evaluated the treatment of patients with acne vulgaris of the face by the two gel formulations locally applied once daily at night for 12 wk. Acne lesion counts (inflammatory, non-inflammatory & total) and severity grading were carried out on the monthly scheduled visits along with the tolerability assessments. Results: A total of 207 patients were randomized in the study. Reductions in the total (72.9% vs. 65.0%; p = 0.03) and inflammatory (78.1% vs. 66.9%; p = 0.02) acne lesions were reported to be significantly greater with the nanogel formulation as compared to the conventional gel formulation. Local adverse events were significantly less (p = 0.04) in the nanogel group (13.3%) as compared to the conventional gel group (24.7%). Dryness was the most common adverse event reported in both the treatment groups while peeling of skin, burning sensation and photosensitivity were reported in patients using the conventional gel only. Conclusion: In the treatment of acne vulgaris of the face, tretinoin nanogel formulation appears to be more effective and better tolerated than the conventional gel formulation. PMID:25738069

  20. Carrier transport properties of the Group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} with and without boron doping

    SciTech Connect

    Ban, Yoshisuke Wakabayashi, Yuki; Akiyama, Ryota; Nakane, Ryosho; Tanaka, Masaaki

    2014-09-15

    We have investigated the transport and magnetic properties of group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} films (x = 1.0 and 2.3%) with and without boron doping grown by molecular beam epitaxy (MBE). In order to accurately measure the transport properties of 100-nm-thick Ge{sub 1-x}Fe{sub x} films, (001)-oriented silicon-on-insulator (SOI) wafers with an ultra-thin Si body layer (∼5 nm) were used as substrates. Owing to the low Fe content, the hole concentration and mobility in the Ge{sub 1-x}Fe{sub x} films were exactly estimated by Hall measurements because the anomalous Hall effect in these films was found to be negligibly small. By boron doping, we increased the hole concentration in Ge{sub 1-x}Fe{sub x} from ∼10{sup 18} cm{sup −3} to ∼10{sup 20} cm{sup −3} (x = 1.0%) and to ∼10{sup 19} cm{sup −3} (x = 2.3%), but no correlation was observed between the hole concentration and magnetic properties. This result presents a contrast to the hole-induced ferromagnetism in III-V ferromagnetic semiconductors.

  1. Reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine with certain group II-IV metals

    SciTech Connect

    Karsanov, I.V.; Ivakhnenko, E.P.; Khandkarova, V.S.; Rubezhov, A.Z.; Okhlobystin, O.Yu.; Minkin, V.I.; Prokof'ev, A.I.; Kabachnik, M.I.

    1987-07-10

    It has already been shown that 2-amino-4,6-di(tert-butyl)phenol reacts with 3,5-di(tert-butyl)-o-benzoquinone to form 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine (I), which is readily reduced by alkali metals to the corresponding semiquinone anion-radical (II), and further to the diamagnetic dianion (IIA). They made use of this ability of (I) to undergo reduction to prepare anion-radical salts with different group II-IV metals in the form of their amalgams. In the EPR spectrum of the anion-radical complex (III) formed in the reduction of (I) by a thallium amalgam, the HFI constants of the unpaired electron with magnetic nuclei of the organic ligand are close to those of the K-salt (II), and a substantial HFI is observed with the /sup 203,205/Tl nuclei. This unequivocally proves that the complex has a semiquinone structure, since an HFI on the /sup 203,205/Tl nuclei of such an order of magnitude is characteristic of o-benzoquinone salts with a thallium cation.

  2. Fabrication of a Core-Shell-Type Photocatalyst via Photodeposition of Group IV and V Transition Metal Oxyhydroxides: An Effective Surface Modification Method for Overall Water Splitting.

    PubMed

    Takata, Tsuyoshi; Pan, Chengsi; Nakabayashi, Mamiko; Shibata, Naoya; Domen, Kazunari

    2015-08-05

    The design of optimal surface structures for photocatalysts is a key to efficient overall water splitting into H2 and O2. A unique surface modification method was devised for a photocatalyst to effectively promote overall water splitting. Photodeposition of amorphous oxyhydroxides of group IV and V transition metals (Ti, Nb, Ta) over a semiconductor photocatalyst from corresponding water-soluble metal peroxide complexes was examined. In this method, amorphous oxyhydroxide covered the whole surface of the photocatalyst particles, creating a core-shell structure. The water splitting behavior of the novel core-shell-type photocatalyst in relation to the permeation behavior of the coating layer was investigated in detail. Overall water splitting proceeded successfully after the photodeposition, owing to the prevention of the reverse reaction. The photodeposited oxyhydroxide layers were found to function as molecular sieves, selectively filtering reactant and product molecules. By exploiting the selective permeability of the coating layer, redox reactions on the photocatalyst surface could be suitably controlled, which resulted in successful overall water splitting.

  3. Endomicrobium proavitum, the first isolate of Endomicrobia class. nov. (phylum Elusimicrobia)--an ultramicrobacterium with an unusual cell cycle that fixes nitrogen with a Group IV nitrogenase.

    PubMed

    Zheng, Hao; Dietrich, Carsten; Radek, Renate; Brune, Andreas

    2016-01-01

    The bacterial tree contains many deep-rooting clades without any cultured representatives. One such clade is 'Endomicrobia', a class-level lineage in the phylum Elusimicrobia represented so far only by intracellular symbionts of termite gut flagellates. Here, we report the isolation and characterization of the first free-living member of this clade from sterile-filtered gut homogenate of defaunated (starch-fed) Reticulitermes santonensis. Strain Rsa215 is a strictly anaerobic ultramicrobacterium that grows exclusively on glucose, which is fermented to lactate, acetate, hydrogen and CO2. Ultrastructural analysis revealed a Gram-negative cell envelope and a peculiar cell cycle. The genome contains a single set of nif genes that encode homologues of Group IV nitrogenases, which were so far considered to have functions other than nitrogen fixation. We documented nitrogenase activity and diazotrophic growth by measuring acetylene reduction activity and (15)N2 incorporation into cell mass, and demonstrated that transcription of nifH and nitrogenase activity occur only in the absence of ammonium. Based on the ancestral relationship to 'Candidatus Endomicrobium trichonymphae' and other obligate endosymbionts, we propose the name 'Endomicrobium proavitum' gen. nov., sp. nov. for the first isolate of this lineage and the name 'Endomicrobia' class. nov. for the entire clade.

  4. Chemoenzymatic synthesis of fluorogenic phospholipids and evaluation in assays of phospholipases A, C and D.

    PubMed

    Piel, Mathilde S; Peters, Günther H J; Brask, Jesper

    2017-01-01

    Phospholipases are ubiquitous in nature and the target of significant research aiming at both their physiological roles and technical applications in e.g. the food industry. In the search for sensitive and selective phospholipase assays, we have focused on synthetic FRET (Förster resonance energy transfer) substrates. This has led to the development of a facile, easily scalable and low cost synthesis of fluorogenic phospholipids featuring the dansyl/dabcyl fluorophore/quencher-pair on the fatty acid ω-position and on the phosphatidylethanolamine head group, respectively. Hence, the two substrates lyso-(dansyl-FA)-GPE-dabcyl (6) and (dansyl-FA)2-GPE-dabcyl (7) were synthesized by a chemoenzymatic strategy, in which preparation of (6) further included a novel selective enzymatic esterification step. As proof of concept, activity of a handful of phospholipases, one from each of the PLA1, PLA2, PLC and PLD classes, were assayed using substrates (6) and (7), and the kinetic parameter kcat/KM was determined. The PLA1 (Lecitase Ultra™) was found to be highly active on both substrates, whereas the PLD (from white cabbage) had no activity, presumably due to steric effects associated with the dabcyl-functionalization of the head group. It was further substantiated that the substrates are specific towards phospholipase activity as the tested lipase (Lipolase™) showed close to zero activity.

  5. Stage IV and age over 45 years are the only prognostic factors of the International Prognostic Score for the outcome of advanced Hodgkin lymphoma in the Spanish Hodgkin Lymphoma Study Group series.

    PubMed

    Guisado-Vasco, Pablo; Arranz-Saez, Reyes; Canales, Miguel; Cánovas, Araceli; Garcia-Laraña, José; García-Sanz, Ramón; Lopez, Andrés; López, José Luis; Llanos, Marta; Moraleda, José Maria; Rodriguez, José; Rayón, Consuelo; Sabin, Pilar; Salar, Antonio; Marín-Niebla, Ana; Morente, Manuel; Sánchez-Godoy, Pedro; Tomás, José Francisco; Muriel, Alfonso; Abraira, Victor; Piris, Miguel A; Garcia, Juán F; Montalban, Carlos

    2012-05-01

    The International Prognostic Score (IPS) is the most widely used system to date for identifying risk groups for the outcome of patients with advanced Hodgkin lymphoma, although important limitations have been recognized. We analyzed the value of the IPS in a series of 311 patients with advanced classical Hodgkin lymphoma (cHL) (Ann Arbor stage III, IV or stage II with B symptoms and/or bulky masses) treated with first-line chemotherapy including adriamycin (adriamycin, bleomycin, vinblastine, dacarbazine [ABVD] or equivalent variants). In univariate and multivariate analyses, stage IV disease and age ≥ 45 years were the only factors with independent predictive significance for overall survival (OS) (p = 0.002 and p < 0.001, respectively). Stage IV was still significant for freedom from progression (FFP) (p = 0.001) and age ≥ 45 years was borderline significant (p = 0.058). IPS separates prognostic groups, as in the original publication, but this is mainly due to the high statistical significance of stage IV and age ≥ 45 years. Moreover, the combination of these two factors enables a simpler system to be constructed that separates groups with different FFP and OS. In conclusion, in our series, stage IV and age ≥ 45 years are the key prognostic factors for the outcome of advanced cHL.

  6. Welding IV.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

  7. The physiological roles of primary phospholipase C.

    PubMed

    Yang, Yong Ryoul; Follo, Matilde Y; Cocco, Lucio; Suh, Pann-Ghill

    2013-09-01

    The roles of phosphoinositide-specific phospholipase C (PLC) have been extensively investigated in diverse cell lines and pathological conditions. Among the PLC isozmes, primary PLCs, PLC-β and PLC-γ, are directly activated by receptor activation, unlike other secondary PLCs (PLC-ɛ, PLC-δ1, and PLC-η1). PLC-β isozymes are activated by G protein couple receptor and PLC-γ isozymes are activated by receptor tyrosine kinase (RTK). Primary PLCs are differentially expressed in different tissues, suggesting their specific roles in diverse tissues and regulate a variety of physiological and pathophysiological functions. Thus, dysregulation of phospholipases contributes to a number of human diseases and primary PLCs have been identified as therapeutic targets for prevention and treatment of diseases. Here we review the roles of primary PLCs in physiology and their impact in pathology.

  8. Multiple extracellular phospholipase activities from Prevotella intermedia.

    PubMed

    Bulkacz, Jaime; Faull, Kym F

    2009-06-01

    Enzyme preparations obtained from Prevotella intermedia culture supernatants were partially purified by ammonium sulfate precipitation and ion-exchange column chromatography. Hydrolytic activities were revealed by an assay that uses silicic acid thin layer chromatography to separate the products derived from (14)C-labeled phosphatidyl-choline (PC) hydrolysis. These products were then measured by liquid scintillation spectrometry after iodine visualization. The assays revealed linearity of substrate depletion and product formation with respect to time and protein concentration up to 30 min of incubation. The products had retention times consistent with lyso-phospholipids and phosphoryl-choline. These data strongly suggests the presence of both phospholipase A (PL-A) and phospholipase C (PL-C) activities.

  9. Negative correlation between phospholipase and esterase activity produced by Fusarium isolates

    PubMed Central

    Ishida, K.; Alviano, D.S.; Silva, B.G.; Guerra, C.R.; Costa, A.S.; Nucci, M.; Alviano, C.S.; Rozental, S.

    2012-01-01

    Fusarium species have emerged as one of the more outstanding groups of clinically important filamentous fungi, causing localized and life-threatening invasive infections with high morbidity and mortality. The ability to produce different types of hydrolytic enzymes is thought to be an important virulence mechanism of fungal pathogens and could be associated with the environment of the microorganism. Here, we have measured the production of two distinct lipolytic enzymes, phospholipase and esterase, by sixteen Fusarium isolates recovered from the hospital environment, immunocompromised patients' blood cultures, foot interdigital space scrapings from immunocompromised patients, and foot interdigital space scrapings from immunocompetent patients (4 isolates each). Fourteen of these 16 isolates were identified as Fusarium solani species complex (FSSC) and two were identified as F. oxysporum species complex (FOSC). Some relevant genus characteristics were visualized by light and electron microscopy such as curved and multicelled macroconidia with 3 or 4 septa, microconidia, phialides, and abundant chlamydospores. All Fusarium isolates were able to produce esterase and phospholipase under the experimental conditions. However, a negative correlation was observed between these two enzymes, indicating that a Fusarium isolate with high phospholipase activity has low esterase activity and vice versa. In addition, Fusarium isolated from clinical material produced more phospholipases, while environmental strains produced more esterases. These observations may be correlated with the different types of substrates that these fungi need to degrade during their nutrition processes. PMID:22415116

  10. C-H bond activation of the methyl group of the supporting ligand in an osmium(III) complex upon reaction with H2O2: formation of an organometallic osmium(IV) complex.

    PubMed

    Sugimoto, Hideki; Ashikari, Kenji; Itoh, Shinobu

    2013-01-18

    Oxidation of the hydroxoosmium(III) complex resulted in C-H bond activation of the methyl group of the supporting ligand (N,N'-dimethyl-2,11-diaza[3.3](2,6)pyridinophane). The product was an osmium(IV) complex exhibiting a seven-coordinate structure with an additional Os-CH(2) bond.

  11. Kinetic Analysis of a Mammalian Phospholipase D

    PubMed Central

    Henage, Lee G.; Exton, John H.; Brown, H. Alex

    2013-01-01

    In mammalian cells, phospholipase D activity is tightly regulated by diverse cellular signals, including hormones, neurotransmitters, and growth factors. Multiple signaling pathways converge upon phospholipase D to modulate cellular actions, such as cell growth, shape, and secretion. We examined the kinetics of protein kinase C and G-protein regulation of mammalian phospholipase D1 (PLD1) in order to better understand interactions between PLD1 and its regulators. Activation by Arf-1, RhoA, Rac1, Cdc42, protein kinase Cα, and phosphatidylinositol 4,5-bisphosphate displayed surface dilution kinetics, but these effectors modulated different kinetic parameters. PKCα activation of PLD1 involves N- and C-terminal PLD domains. Rho GTPases were binding activators, enhancing the catalytic efficiency of a purified PLD1 catalytic domain via effects on Km. Arf-1, a catalytic activator, stimulated PLD1 by enhancing the catalytic constant, kcat. A kinetic description of PLD1 activation by multiple modulators reveals a mechanism for apparent synergy between activators. Synergy was observed only when PLD1 was simultaneously stimulated by a binding activator and a catalytic activator. Surprisingly, synergistic activation was steeply dependent on phosphatidylinositol 4,5-bisphosphate and phosphatidylcholine. Together, these findings suggest a role for PLD1 as a signaling node, in which integration of convergent signals occurs within discrete locales of the cellular membrane. PMID:16339153

  12. The diversity of algal phospholipase D homologs revealed by biocomputational analysis.

    PubMed

    Beligni, María Verónica; Bagnato, Carolina; Prados, María Belén; Bondino, Hernán; Laxalt, Ana María; Munnik, Teun; Ten Have, Arjen

    2015-10-01

    Phospholipase D (PLD) participates in the formation of phosphatidic acid, a precursor in glycerolipid biosynthesis and a second messenger. PLDs are part of a superfamily of proteins that hydrolyze phosphodiesters and share a catalytic motif, HxKxxxxD, and hence a mechanism of action. Although HKD-PLDs have been thoroughly characterized in plants, animals and bacteria, very little is known about these enzymes in algae. To fill this gap in knowledge, we performed a biocomputational analysis by means of HMMER iterative profiling, using most eukaryotic algae genomes available. Phylogenetic analysis revealed that algae exhibit very few eukaryotic-type PLDs but possess, instead, many bacteria-like PLDs. Among algae eukaryotic-type PLDs, we identified C2-PLDs and PXPH-like PLDs. In addition, the dinoflagellate Alexandrium tamarense features several proteins phylogenetically related to oomycete PLDs. Our phylogenetic analysis also showed that algae bacteria-like PLDs (proteins with putative PLD activity) fall into five clades, three of which are novel lineages in eukaryotes, composed almost entirely of algae. Specifically, Clade II is almost exclusive to diatoms, whereas Clade I and IV are mainly represented by proteins from prasinophytes. The other two clades are composed of mitochondrial PLDs (Clade V or Mito-PLDs), previously found in mammals, and a subfamily of potentially secreted proteins (Clade III or SP-PLDs), which includes a homolog formerly characterized in rice. In addition, our phylogenetic analysis shows that algae have non-PLD members within the bacteria-like HKD superfamily with putative cardiolipin synthase and phosphatidylserine/phosphatidylglycerophosphate synthase activities. Altogether, our results show that eukaryotic algae possess a moderate number of PLDs that belong to very diverse phylogenetic groups.

  13. IVS Organization

    NASA Technical Reports Server (NTRS)

    2004-01-01

    International VLBI Service (IVS) is an international collaboration of organizations which operate or support Very Long Baseline Interferometry (VLBI) components. The goals are: To provide a service to support geodetic, geophysical and astrometric research and operational activities. To promote research and development activities in all aspects of the geodetic and astrometric VLBI technique. To interact with the community of users of VLBI products and to integrate VLBI into a global Earth observing system.

  14. Phospholipase and Aspartyl Proteinase Activities of Candida Species Causing Vulvovaginal Candidiasis in Patients with Type 2 Diabetes Mellitus.

    PubMed

    Bassyouni, Rasha H; Wegdan, Ahmed Ashraf; Abdelmoneim, Abdelsamie; Said, Wessam; AboElnaga, Fatma

    2015-10-01

    Few research had investigated the secretion of phospholipase and aspartyl proteinase from Candida spp. causing infection in females with type 2 diabetes mellitus. This research aimed to investigate the prevalence of vulvovaginal candidiasis (VVC) in diabetic versus non-diabetic women and compare the ability of identified Candida isolates to secrete phospholipases and aspartyl proteinases with characterization of their genetic profile. The study included 80 females with type 2 diabetes mellitus and 100 non-diabetic females within the child-bearing period. Candida strains were isolated and identified by conventional microbiological methods and by API Candida. The isolates were screened for their extracellular phospholipase and proteinase activities by culturing them on egg yolk and bovine serum albumin media, respectively. Detection of aspartyl proteinase genes (SAP1 to SAP8) and phospholipase genes (PLB1, PLB2) were performed by multiplex polymerase chain reaction. Our results indicated that vaginal candidiasis was significantly higher among the diabetic group versus nondiabetic group (50% versus 20%, respectively) (p = 0.004). C. albicans was the most prevalent species followed by C. glabrata in both groups. No significant association between diabetes mellitus and phospholipase activities was detected (p = 0.262), whereas high significant proteinase activities exhibited by Candida isolated from diabetic females were found (82.5%) (p = 0.000). Non-significant associations between any of the tested proteinase or phospholipase genes and diabetes mellitus were detected (p > 0.05). In conclusion, it is noticed that the incidence of C. glabrata causing VVC is increased. The higher prevalence of vaginal candidiasis among diabetics could be related to the increased aspartyl proteinase production in this group of patients.

  15. Intracellular signaling by phospholipase D as a therapeutic target.

    PubMed

    Steed, P M; Chow, A H

    2001-09-01

    The pharmaceutical industry has recently focused on intracellular signaling as a means to integrate the multiple facets of complex disease states, such as inflammation, because these pathways respond to numerous extracellular signals and coordinate a collection of cell responses contributing to pathology. One critical aspect of intracellular signaling is regulation of key cell functions by lipid mediators, in particular the generation of a key mediator, phosphatidic acid (PA) via the hydrolysis of phosphatidylcholine by phospholipase D (PLD). Research in this field has intensified, due in part to the recent cloning and partial characterization of the two PLD isoforms in mammalian cells, and this work has contributed significantly to our understanding of events downstream of PA generation. It is these effector functions of PLD activity that make this pathway attractive as a therapeutic target while the biochemical properties of the PLD isozymes make them amenable to small molecule intervention. Recent studies indicate that PA, and its immediate metabolites diacylglycerol and lyso-PA, affect numerous cellular pathways including ligand-mediated secretion, cytoskeletal reorganisations, respiratory burst, prostaglandin release, cell migration, cytokine release, and mitogenesis. This review summarises the data implicating signaling via PLD in these cell functions, obtained from: (i) molecular analyses of PLD/effector interactions, (ii) correlation between PA production and cell responses, (iii) experimental manipulation of PA levels, (iv) inhibition of PLD regulators, and (v) direct inhibition of PA production. The utility of targeting PLD signaling for the treatment of acute/chronic inflammation and other indications is discussed in light of these data.

  16. Effects of dexamethasone on palate mesenchymal cell phospholipase activity

    SciTech Connect

    Bulleit, R.F.; Zimmerman, E.F.

    1984-09-15

    Corticosteroids will induce cleft palate in mice. One suggested mechanism for this effect is through inhibition of phospholipase activity. This hypothesis was tested by measuring the effects of dexamethasone, a synthetic corticosteroid, on phospholipase activity in cultures of palate mesenchymal cells. Palate mesenchymal cells were prelabeled with (3H)arachidonic acid. The cells were subsequently treated with various concentrations of dexamethasone. Concurrently, cultures of M-MSV-transformed 3T3 cells were prepared identically. After treatment, phospholipase activity was stimulated by the addition of serum or epidermal growth factor (EGF), and radioactivity released into the medium was taken as a measure of phospholipase activity. Dexamethasone (1 X 10(-5) or 1 X 10(-4) M) could inhibit serum-stimulated phospholipase activity in transformed 3T3 cells after 1 to 24 hr of treatment. However, no inhibition of activity was measured in palate mesenchymal cells following this period of treatment. Not until 120 hr of treatment with dexamethasone (1 X 10(-4) M) was any significant inhibition of serum-stimulated phospholipase activity observed in palate mesenchymal cells. When EGF was used to stimulate phospholipase activity, dexamethasone (1 X 10(-5) M) caused an increase in phospholipase activity in palate mesenchymal cells. These observations suggested that phospholipase in transformed 3T3 cells was sensitive to inhibition by dexamethasone. However, palate mesenchymal cell phospholipase is only minimally sensitive to dexamethasone, and in certain instances can be enhanced. These results cannot support the hypothesis that corticosteroids mediate their teratogenic effect via inhibition of phospholipase activity.

  17. Crystallization and preliminary X-ray diffraction analysis of three myotoxic phospholipases A2 from Bothrops brazili venom

    PubMed Central

    Fernandes, Carlos A. H.; Gartuzo, Elaine C. G.; Pagotto, Ivan; Comparetti, Edson J.; Huancahuire-Vega, Salomón; Ponce-Soto, Luis Alberto; Costa, Tássia R.; Marangoni, Sergio; Soares, Andreimar M.; Fontes, Marcos R. M.

    2012-01-01

    Two myotoxic and noncatalytic Lys49-phospholipases A2 (braziliantoxin-II and MT-II) and a myotoxic and catalytic phospholipase A2 (braziliantoxin-III) from the venom of the Amazonian snake Bothrops brazili were crystallized. The crystals diffracted to resolutions in the range 2.56–2.05 Å and belonged to space groups P3121 (braziliantoxin-II), P6522 (braziliantoxin-III) and P21 (MT-II). The structures were solved by molecular-replacement techniques. Both of the Lys49-phospholipases A2 (braziliantoxin-II and MT-II) contained a dimer in the asymmetric unit, while the Asp49-phospholipase A2 braziliantoxin-III contained a monomer in its asymmetric unit. Analysis of the quaternary assemblies of the braziliantoxin-II and MT-II structures using the PISA program indicated that both models have a dimeric conformation in solution. The same analysis of the braziliantoxin-III structure indicated that this protein does not dimerize in solution and probably acts as a monomer in vivo, similar to other snake-venom Asp49-phospholipases A2. PMID:22869126

  18. Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium.

    PubMed

    Ilaiyaraja, P; Deb, A K Singha; Ponraju, D; Ali, Sk Musharaf; Venkatraman, B

    2017-04-15

    A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH >4) and nitric acid media (>3M). The sorption equilibrium could be reached within 60min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG5-SDB was estimated to be about 682 and 544.2mgg(-1) respectively at 25°C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings.

  19. Antibacterial properties of intestinal phospholipase A2 from the common stingray Dasyatis pastinaca.

    PubMed

    Ben Bacha, Abir; Abid, Islem; Horchani, Habib

    2012-11-01

    Stingray phospholipase A(2) group IIA (SPLA(2)-IIA) was recently isolated and purified to homogeneity from the intestine of the common stingray Dasyatis pastinaca, suggesting that this enzyme plays an important role in systemic bactericidal defense. The present study showed that SPLA(2)-IIA was highly bactericidal against Gram-positive bacteria with inhibition zones and minimal inhibitory concentration values in the range of 13-25 mm and 2-8 μg/ml, respectively, whereas Gram-negative bacteria exhibited a much higher resistance. The bactericidal efficiency of SPLA(2)-IIA was shown to be unaffected by high protein and salt concentrations, but dependent upon the presence of calcium ions, and then correlated to the hydrolytic activity of membrane phospholipids. Importantly, we showed that stingray phospholipase A(2) group IIA presents no cytotoxicity after its incubation with MDA-MB-231 cells. SPLA(2)-IIA may be considered as a future therapeutic agent against bacterial infections.

  20. Thyroid hormone status regulates the expression of secretory phospholipases.

    PubMed

    Sharma, Pragya; Levesque, Tania; Boilard, Eric; Park, Edwards A

    2014-01-31

    Thyroid hormone (T3) stimulates various metabolic pathways and the hepatic actions of T3 are mediated primarily through the thyroid hormone receptor beta (TRβ). Hypothyroidism has been linked with low grade inflammation, elevated risk of hepatic steatosis and atherosclerosis. Secretory phospholipases (sPLA2) are associated with inflammation, hyperlipidemia and atherosclerosis. Due to potential linkage between thyroid hormone and sPLA2, we investigated the effect of thyroid hormone status on the regulation of secretory phospholipases in mice, rats and human liver. T3 suppressed the expression of the sPLA2 group IIa (PLA2g2a) gene in the liver of BALB/c mice and C57BL/6 transgenic mice expressing the human PLA2g2a. PLA2g2a was elevated with hypothyroidism and high fat diets which may contribute to the low grade inflammation associated with hypothyroidism and diet induced obesity. We also examined the effects of the TRβ agonist eprotirome on hepatic gene regulation. We observed that eprotirome inhibited the expression of selected sPLA2 genes and furthermore the cytokine mediated induction PLA2g2a was suppressed. In addition, eprotirome induced genes involved in fatty acid oxidation and cholesterol clearance while inhibiting lipogenic genes. Our results indicate that in vivo thyroid hormone status regulates the abundance of sPLA2 and the inhibition of PLA2g2a by T3 is conserved across species. By regulating sPLA2 genes, T3 may impact processes associated with atherosclerosis and inflammation and TRβ agonists may ameliorate inflammation and hyperlipidemia.

  1. Thyroid hormone status regulates the expression of secretory phospholipases

    PubMed Central

    Sharma, Pragya; Levesque, Tania; Boilard, Eric; Park, Edwards A.

    2014-01-01

    Thyroid hormone (T3) stimulates various metabolic pathways and the hepatic actions of T3 are mediated primarily through the thyroid hormone receptor beta (TRβ). Hypothyroidism has been linked with low grade inflammation, elevated risk of hepatic steatosis and atherosclerosis. Secretory phospholipases (sPLA2) are associated with inflammation, hyperlipidemia and atherosclerosis. Due to potential linkage between thyroid hormone and sPLA2, we investigated the effect of thyroid hormone status on the regulation of secretory phospholipases in mice, rats and human liver. T3 suppressed the expression of the sPLA2 group IIa (PLA2g2a) gene in the liver of BALB/c mice and C57BL/6 transgenic mice expressing the human PLA2g2a. PLA2g2a was elevated with hypothyroidism and high fat diets which may contribute to the low grade inflammation associated with hypothyroidism and diet induced obesity. We also examined the effects of the TRβ agonist eprotirome on hepatic gene regulation. We observed that eprotirome inhibited the expression of selected sPLA2 genes and furthermore the cytokine mediated induction PLA2g2a was suppressed. In addition, eprotirome induced genes involved in fatty acid oxidation and cholesterol clearance while inhibiting lipogenic genes. Our results indicate that in vivo thyroid hormone status regulates the abundance of sPLA2 and the inhibition of PLA2g2a by T3 is conserved across species. By regulating sPLA2 genes, T3 may impact processes associated with atherosclerosis and inflammation and TRβ agonists may ameliorate inflammation and hyperlipidemia. PMID:24440706

  2. The correlation between anti phospholipase A2 specific IgE and clinical symptoms after a bee sting in beekeepers

    PubMed Central

    Matysiak, Joanna; Bręborowicz, Anna; Dereziński, Paweł; Kokot, Zenon J.

    2016-01-01

    Introduction Beekeepers are a group of people with high exposure to honeybee stings and with a very high risk of allergy to bee venom. Therefore, they are a proper population to study the correlations between clinical symptoms and results of diagnostic tests. Aim The primary aim of our study was to assess the correlations between total IgE, venom- and phospholipase A2-specific IgE and clinical symptoms after a bee sting in beekeepers. The secondary aim was to compare the results of diagnostic tests in beekeepers and in individuals with standard exposure to bees. Material and methods Fifty-four individuals were divided into two groups: beekeepers and control group. The levels of total IgE (tIgE), venom-specific IgE (venom sIgE), and phospholipase A2-specific IgE (phospholipase A2 sIgE) were analyzed. Results Our study showed no statistically significant correlation between the clinical symptoms after a sting and tIgE in the entire analyzed group. There was also no correlation between venom sIgE level and clinical symptoms either in beekeepers or in the group with standard exposure to bees. We observed a statistically significant correlation between phospholipase A2 sIgE level and clinical signs after a sting in the group of beekeepers, whereas no such correlation was detected in the control group. Significantly higher venom-specific IgE levels in the beekeepers, as compared to control individuals were shown. Conclusions In beekeepers, the severity of clinical symptoms after a bee sting correlated better with phospholipase A2 sIgE than with venom sIgE levels. PMID:27512356

  3. Reminiscence of phospholipase B in Penicillium notatum.

    PubMed

    Saito, Kunihiko

    2014-01-01

    Since the phospholipase B (PLB) was reported as a deacylase of both lecithin and lysolecithin yielding fatty acids and glycerophosphocholine (GPC), there was a question as to whether it is a single enzyme or a mixture of a phospholipase A2 (PLA2) and a lysophospholipase (LPL). We purified the PLB in Penicillium notatum and showed that it catalyzed deacylation of sn-1 and sn-2 fatty acids of 1,2-diacylphospholipids and also sn-1 or sn-2 fatty acids of 1- or 2-monoacylphospholipids (lysophospholipids). Further, it also has a monoacyllipase activity. The purified PLB is a glycoprotein with m.w. of 91,300. The sugar moiety is M9 only and the protein moiety consists of 603 amino acids. PLB, different from PLA2, shows other enzymatic activities, such as transacylase, lipase and acylesterase. PLB activity is influenced by various substances, e.g. detergents, deoxycholate, diethylether, Fe(3+), and endogenous protease. Therefore, PLB might have broader roles than PLA2 in vivo. The database shows an extensive sequence similarity between P. notatum PLB and fungal PLB, cPLA2 and patatin, suggesting a homologous relationship. The catalytic triad of cPLA2, Ser, Asp and Arg, is also present in P. notatum PLB. Other related PLBs, PLB/Lipases are discussed.

  4. A chromogenic substrate for phosphatidylinositol-specific phospholipase C: 4-nitrophenyl myo-inositol-1-phosphate.

    PubMed

    Shashidhar, M S; Volwerk, J J; Griffith, O H; Keana, J F

    1991-12-01

    A chromogenic water-soluble substrate for phosphatidylinositol-specific phospholipase C was synthesized starting from myo-inositol employing isopropylidene and 4-methoxytetrahydropyranyl protecting groups. In this analogue of phosphatidylinositol, 4-nitrophenol replaces the diacylglycerol moiety, resulting in synthetic, racemic 4-nitrophenyl myo-inositol-1-phosphate. Using this synthetic substrate a rapid, convenient and sensitive spectrophotometric assay for the phosphatidylinositol-specific phospholipase C from Bacillus cereus was developed. Initial rates of the cleavage of the nitrophenol substrate were linear with time and the amount of enzyme used. At pH 7.0, specific activities for the B. cereus enzyme were 77 and 150 mumol substrate cleaved min-1 (mg protein)-1 at substrate concentrations of 1 and 2 mM, respectively. Under these conditions, less than 50 ng quantities of enzyme were easily detected. The chromogenic substrate was stable during long term storage (6 months) as a solid at -20 degrees C.

  5. Activity of phospholipase C and release of prostaglandin F2 alpha by endometrial tissue from ovariectomized ewes receiving progesterone and estradiol.

    PubMed

    Raw, R E; Silvia, W J

    1991-03-01

    Progesterone and estradiol interact to regulate secretion of prostaglandin (PG) F2 alpha from the ovine endometrium in response to oxytocin. Two experiments were conducted to determine if these effects were due to changes in activity of phospholipase C or in the second messenger responsive pathways that regulate production of PGF2 alpha. In both experiments, ovariectomized ewes were assigned to one of four treatment groups (control, estradiol, progesterone, progesterone and estradiol). Steroids were administered, in vivo, to mimic the changes that occur during the estrous cycle. On Day 16 of steroid treatment, endometrial tissue was collected and incubated, in vitro, to measure activity of phospholipase C and release of PGF2 alpha. Treatment with progesterone, in vivo, enhanced basal and oxytocin-induced activity of phospholipase C and release of PGF2 alpha, in vitro. Estradiol suppressed oxytocin-induced activity of phospholipase C, both in the presence and absence of progesterone. In contrast to its effects on phospholipase C, estradiol inhibited basal and oxytocin-induced release of PGF2 alpha when administered alone, but not when administered with progesterone. Steroids had similar effects on the release of PGF2 alpha induced by phorbol 12-myristate 13-acetate and A23187. It was concluded that progesterone and estradiol regulate endometrial release of PGF2 alpha by affecting both the activity of phospholipase C and its associated second messenger responsive pathways that may regulate production of PGF2 alpha.

  6. Asteroids IV

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    . Asteroids, like planets, are driven by a great variety of both dynamical and physical mechanisms. In fact, images sent back by space missions show a collection of small worlds whose characteristics seem designed to overthrow our preconceived notions. Given their wide range of sizes and surface compositions, it is clear that many formed in very different places and at different times within the solar nebula. These characteristics make them an exciting challenge for researchers who crave complex problems. The return of samples from these bodies may ultimately be needed to provide us with solutions. In the book Asteroids IV, the editors and authors have taken major strides in the long journey toward a much deeper understanding of our fascinating planetary ancestors. This book reviews major advances in 43 chapters that have been written and reviewed by a team of more than 200 international authorities in asteroids. It is aimed to be as comprehensive as possible while also remaining accessible to students and researchers who are interested in learning about these small but nonetheless important worlds. We hope this volume will serve as a leading reference on the topic of asteroids for the decade to come. We are deeply indebted to the many authors and referees for their tremendous efforts in helping us create Asteroids IV. We also thank the members of the Asteroids IV scientific organizing committee for helping us shape the structure and content of the book. The conference associated with the book, "Asteroids Comets Meteors 2014" held June 30-July 4, 2014, in Helsinki, Finland, did an outstanding job of demonstrating how much progress we have made in the field over the last decade. We are extremely grateful to our host Karri Muinonnen and his team. The editors are also grateful to the Asteroids IV production staff, namely Renée Dotson and her colleagues at the Lunar and Planetary Institute, for their efforts, their invaluable assistance, and their enthusiasm; they made life as

  7. Phospholipase C-β in immune cells.

    PubMed

    Kawakami, Toshiaki; Xiao, Wenbin

    2013-09-01

    Great progress has recently been made in structural and functional research of phospholipase C (PLC)-β. We now understand how PLC-β isoforms (β1-β4) are activated by GTP-bound Gαq downstream of G protein-coupled receptors. Numerous studies indicate that PLC-βs participate in the differentiation and activation of immune cells that control both the innate and adaptive immune systems. The PLC-β3 isoform also interplays with tyrosine kinase-based signaling pathways, to inhibit Stat5 activation by recruiting the protein-tyrosine phosphatase SHP-1, with which PLC-β3 and Stat5 form a multi-molecular signaling platform, named SPS complex. The SPS complex has important regulatory roles in tumorigenesis and immune cell activation.

  8. Primary phospholipase C and brain disorders.

    PubMed

    Yang, Yong Ryoul; Kang, Du-Seock; Lee, Cheol; Seok, Heon; Follo, Matilde Y; Cocco, Lucio; Suh, Pann-Ghill

    2016-05-01

    In the brain, the primary phospholipase C (PLC) proteins, PLCβ, and PLCγ, are activated primarily by neurotransmitters, neurotrophic factors, and hormones through G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). Among the primary PLC isozymes, PLCβ1, PLCβ4, and PLCγ1 are highly expressed and differentially distributed, suggesting a specific role for each PLC subtype in different regions of the brain. Primary PLCs control neuronal activity, which is important for synapse function and development. In addition, dysregulation of primary PLC signaling is linked to several brain disorders including epilepsy, schizophrenia, bipolar disorder, Huntington's disease, depression and Alzheimer's disease. In this review, we included current knowledge regarding the roles of primary PLC isozymes in brain disorders.

  9. Phospholipase A2-activating protein is associated with a novel form of leukoencephalopathy.

    PubMed

    Falik Zaccai, Tzipora C; Savitzki, David; Zivony-Elboum, Yifat; Vilboux, Thierry; Fitts, Eric C; Shoval, Yishay; Kalfon, Limor; Samra, Nadra; Keren, Zohar; Gross, Bella; Chasnyk, Natalia; Straussberg, Rachel; Mullikin, James C; Teer, Jamie K; Geiger, Dan; Kornitzer, Daniel; Bitterman-Deutsch, Ora; Samson, Abraham O; Wakamiya, Maki; Peterson, Johnny W; Kirtley, Michelle L; Pinchuk, Iryna V; Baze, Wallace B; Gahl, William A; Kleta, Robert; Anikster, Yair; Chopra, Ashok K

    2017-02-01

    Leukoencephalopathies are a group of white matter disorders related to abnormal formation, maintenance, and turnover of myelin in the central nervous system. These disorders of the brain are categorized according to neuroradiological and pathophysiological criteria. Herein, we have identified a unique form of leukoencephalopathy in seven patients presenting at ages 2 to 4 months with progressive microcephaly, spastic quadriparesis, and global developmental delay. Clinical, metabolic, and imaging characterization of seven patients followed by homozygosity mapping and linkage analysis were performed. Next generation sequencing, bioinformatics, and segregation analyses followed, to determine a loss of function sequence variation in the phospholipase A2-activating protein encoding gene (PLAA). Expression and functional studies of the encoded protein were performed and included measurement of prostaglandin E2 and cytosolic phospholipase A2 activity in membrane fractions of fibroblasts derived from patients and healthy controls. Plaa-null mice were generated and prostaglandin E2 levels were measured in different tissues. The novel phenotype of our patients segregated with a homozygous loss-of-function sequence variant, causing the substitution of leucine at position 752 to phenylalanine, in PLAA, which causes disruption of the protein's ability to induce prostaglandin E2 and cytosolic phospholipase A2 synthesis in patients' fibroblasts. Plaa-null mice were perinatal lethal with reduced brain levels of prostaglandin E2 The non-functional phospholipase A2-activating protein and the associated neurological phenotype, reported herein for the first time, join other complex phospholipid defects that cause leukoencephalopathies in humans, emphasizing the importance of this axis in white matter development and maintenance.

  10. Phospholipase and proteinase activities of Candida isolates from denture wearers.

    PubMed

    Marcos-Arias, Cristina; Eraso, Elena; Madariaga, Lucila; Aguirre, Jose Manuel; Quindós, Guillermo

    2011-07-01

    The aim of the present study was to characterise phospholipase and proteinase activities of oral Candida isolates from 100 denture wearers and to study the relationship of these activities with denture stomatitis. Of 100 patients studied, 44 suffered from denture stomatitis. Specimens were collected by swabbing the denture and underlying mucosa. Isolates were previously identified by conventional mycological and genotypic methods. The phospholipase and proteinase activities were evaluated by agar plate methods. A total of 152 isolates were recovered from denture and underlying mucosa, including 101 Candida albicans, 18 Candida tropicalis, 14 Candida glabrata, 11 Candida guilliermondii, four Candida parapsilosis, two Saccharomyces cerevisiae and one isolate each of Candida dubliniensis and Candida krusei. Most C. albicans (97%) showed phospholipase activity; furthermore, the unique C. dubliniensis isolate showed a moderate phospholipase activity. The isolation of C. albicans (chi-square test, P = 0.0016) and phospholipase production by Candida spp. (chi-square test, P = 0.0213) was found to be significantly associated with denture stomatitis. Proteinase production was observed in <30% of isolates, and it was not related to the presence of denture stomatitis (P = 0.7675). Candida albicans isolates may produce both virulence factors, although the proteinase production was only observed in <30% of the isolates. Phospholipase production was exclusive of C. albicans and C. dubliniensis.

  11. Preservation of bilayer structure in human erythrocytes and erythrocyte ghosts after phospholipase treatment. A 31P-NMR study.

    PubMed

    van Meer, G; de Kruijff, B; op den Kamp, J A; van Deenen, L L

    1980-02-15

    1. Fresh human erythrocytes were treated with lytic and non-lytic combinations of phospholipases A2, C and sphingomyelinase. The 31P-NMR spectra of ghosts derived from such erythrocytes show that, in all cases, the residual phospholipids and lysophospholipids remain organized in a bilayer configuration. 2. A bilayer configuration of the (lyso)phospholipids was also observed after treatment of erythrocyte ghosts with various phospholipases even in the case that 98% of the phospholipid was converted into lysophospholipid (72%) and ceramides (26%). 3. A slightly decreased order of the phosphate group of phospholipid molecules, seen as reduced effective chemical shift anisotropy in the 31P-NMR spectra, was found following the formation of diacyglycerols and ceramides in the membrane of intact erythrocytes. Treatment of ghosts always resulted in an extensive decrease in the order of the phosphate groups. 4. The results allow the following conclusions to made: a. Hydrolysis of phospholipids in intact red cells and ghosts does not result in the formation of non-bilayer configuration of residual phospholipids and lysophospholipids. b. Haemolysis, which is obtained by subsequent treatment of intact cells with sphingomyelinase and phospholipase A2, or with phospholipase C, cannot be ascribed to the formation of non-bilayer configuration of phosphate-containing lipids. c. Preservation of bilayer structure, even after hydrolysis of all phospholipid, shows that other membrane constitutents, e.g. cholesterol and/or membrane proteins play an important role in stabilizing the structure of the erythrocyte membrane. d. A major prerequisite for the application of phospholipases in lipid localization studies, the preservation of a bilayer configuration during phospholipid hydrolysis, is met for the erythrocyte membrane.

  12. Exploiting knowledge of R/Avr genes to rapidly clone a new LZ-NBS-LRR family of late blight resistance genes from potato linkage group IV.

    PubMed

    Lokossou, Anoma A; Park, Tae-ho; van Arkel, Gert; Arens, Marjon; Ruyter-Spira, Carolien; Morales, Juan; Whisson, Steve C; Birch, Paul R J; Visser, Richard G F; Jacobsen, Evert; van der Vossen, Edwin A G

    2009-06-01

    In addition to the resistance to Phytophthora infestans (Rpi) genes Rpi-blb1 and Rpi-blb2, Solanum bulbocastanum appears to harbor Rpi-blb3 located at a major late blight resistance locus on LG IV, which also harbors Rpi-abpt, R2, R2-like, and Rpi-mcd1 in other Solanum spp. Here, we report the cloning and functional analyses of four Rpi genes, using a map-based cloning approach, allele-mining strategy, Gateway technology, and transient complementation assays in Nicotiana benthamiana. Rpi-blb3, Rpi-abpt, R2, and R2-like contain all signature sequences characteristic of leucine zipper nucleotide binding site leucine-rich repeat (LZ-NBS-LRR) proteins, and share amino-acid sequences 34.9% similar to RPP13 from Arabidopsis thaliana. The LRR domains of all four Rpi proteins are highly homologous whereas LZ and NBS domains are more polymorphic, those of R2 being the most divergent. Clear blocks of sequence affiliation between the four functional resistance proteins and those encoded by additional Rpi-blb3 gene homologs suggest exchange of LZ, NBS, and LRR domains, underlining the modular nature of these proteins. All four Rpi genes recognize the recently identified RXLR effector PiAVR2.

  13. Crystallization and preliminary X-ray crystallographic analysis of the heterodimeric crotoxin complex and the isolated subunits crotapotin and phospholipase A{sub 2}

    SciTech Connect

    Santos, K. F.; Murakami, M. T.; Toyama, M. H.; Marangoni, S.; Forrer, V. P.; Brandão Neto, J. R.; Polikarpov, I.; Arni, R. K.

    2007-04-01

    Crotoxin, a potent neurotoxin from the venom of the South American rattlesnake Crotalus durissus terrificus, exists as a heterodimer formed between a phospholipase A{sub 2} and a catalytically inactive acidic phospholipase A{sub 2} analogue (crotapotin). Large single crystals of the crotoxin complex and of the isolated subunits have been obtained. Crotoxin, a potent neurotoxin from the venom of the South American rattlesnake Crotalus durissus terrificus, exists as a heterodimer formed between a phospholipase A{sub 2} and a catalytically inactive acidic phospholipase A{sub 2} analogue (crotapotin). Large single crystals of the crotoxin complex and of the isolated subunits have been obtained. The crotoxin complex crystal belongs to the orthorhombic space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 38.2, b = 68.7, c = 84.2 Å, and diffracted to 1.75 Å resolution. The crystal of the phospholipase A{sub 2} domain belongs to the hexagonal space group P6{sub 1}22 (or its enantiomorph P6{sub 5}22), with unit-cell parameters a = b = 38.7, c = 286.7 Å, and diffracted to 2.6 Å resolution. The crotapotin crystal diffracted to 2.3 Å resolution; however, the highly diffuse diffraction pattern did not permit unambiguous assignment of the unit-cell parameters.

  14. Synthesis and Molecular Structure of a Water-Soluble, Dimeric Tri-Titanium(IV)-Substituted Wells-Dawson Polyoxometalate Containing Two Bridging (C5Me5)Rh2+ Groups.

    PubMed

    Matsuki, Yusuke; Hoshino, Takahiro; Takaku, Shoko; Matsunaga, Satoshi; Nomiya, Kenji

    2015-12-07

    A novel trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM)-based organometallic complex, i.e., a dimeric POM containing two bridging Cp*Rh(2+) groups (Cp* = C5Me5) or [{α-P2W15Ti3O60(OH)2}2(Cp*Rh)2](16-) (D-1) with Ci symmetry, was synthesized in an analytically pure form by a 1:2 -molar ratio reaction of the organometallic precursor [Cp*RhCl2]2 with the separately prepared, monomeric trititanium(IV)-substituted Wells-Dawson POM, "[P2W15Ti3O59(OH)3](9-)" (M-1). The crystalline sample (NaK-D-1) of the water-soluble, mixed sodium/potassium salt of D-1 was obtained in the 14.7% yield, which has been characterized by complete elemental analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solution ((183)W, (31)P, (1)H and (13)C{(1)H}) NMR spectroscopy. Single-crystal X-ray structure analysis revealed that the two species of the protonated Wells-Dawson subunits, "[P2W15Ti3O60(OH)2](10-)" were bridged by the two Cp*Rh(2+) groups, resulting in the an overall Ci symmetry. The Cp*Rh(2+) groups were linked to the two terminal oxygen atoms of the titanium(IV) sites and one edge-sharing oxygen atom of the surface Ti-O-Ti bond. The (183)W NMR of D-1 dissolved in D2O showed that its solution structure was represented as a dimeric POM with a formula of [{α-P2W15Ti3O60(OH)3}2{Cp*Rh(OH)}2](16-) (D-2) with Ci (or S2) symmetry. A trititanium(IV)-substituted Wells-Dawson POM-supported organometallic complex has never been reported so far, and thus D-1 in the solid state and D-2 in solution are the first example of this type of complex.

  15. High plasma phospholipase A2 activity, inflammation markers, and LDL alterations in obesity with or without type 2 diabetes.

    PubMed

    Garces, Fatima; López, Flor; Niño, Cladimar; Fernandez, Anazita; Chacin, Luis; Hurt-Camejo, Eva; Camejo, Germán; Apitz-Castro, Rafael

    2010-10-01

    Plasma phospholipases A(2) (PLA(2)) hydrolyze phospholipids of circulating lipoproteins or deposited in arteries producing bioactive lipids believed to contribute to the atherosclerotic inflammatory response. PLA(2)(s) are elevated in obesity and type 2 diabetes (T2D) but it is not clear which of these conditions is the cause since they frequently coexist. This study attempts to evaluate if high plasma PLA(2)(s) activities and markers of their effects in lipoproteins are associated with obesity or T2D diabetes, or with both. Total PLA(2) and Ca(2+)-dependent and -independent activities, lipids, lipoproteins, apoAI, and apoB apolipoproteins and affinity of apoB-lipoproteins for arterial proteoglycans were measured, as well as Inflammation markers. These parameters were evaluated in plasma samples of four groups: (i) apparently healthy controls with normal BMI (nBMI), (ii) obese subjects with no T2D, (iii) patients with T2D but with nBMI, and (iv) obese patients with T2D. PLA(2) activities were measured in the presence and absence of Ca(2+) and in the presence of specific inhibitors. Obese subjects, with or without T2D, had high activities of total PLA(2) and of Ca(2+)-dependent and Ca(2+)-independent enzymes. The activities were correlated with inflammation markers in obese subjects with and without diabetes and with alterations of low-density lipoproteins (LDLs) that increased their affinity for arterial proteoglycans. Ca(2+)-dependent secretory (sPLA(2)) enzymes were the main responsible of the obesity-associated high activity. We speculate that augmented PLA(2)(s) activity that increases affinity of circulating LDL for arterial intima proteoglycans could be another atherogenic component of obesity.

  16. Multiple roles of phosphoinositide-specific phospholipase C isozymes.

    PubMed

    Suh, Pann-Ghill; Park, Jae-Il; Manzoli, Lucia; Cocco, Lucio; Peak, Joanna C; Katan, Matilda; Fukami, Kiyoko; Kataoka, Tohru; Yun, Sanguk; Ryu, Sung Ho

    2008-06-30

    Phosphoinositide-specific phospholipase C is an effector molecule in the signal transduction process. It generates two second messengers, inositol-1,4,5-trisphosphate and diacylglycerol from phosphatidylinositol 4,5-bisphosphate. Currently, thirteen mammal PLC isozymes have been identified, and they are divided into six groups: PLC-beta, -gamma, -delta, -epsilon, -zeta and -eta. Sequence analysis studies demonstrated that each isozyme has more than one alternative splicing variant. PLC isozymes contain the X and Y domains that are responsible for catalytic activity. Several other domains including the PH domain, the C2 domain and EF hand motifs are involved in various biological functions of PLC isozymes as signaling proteins. The distribution of PLC isozymes is tissue and organ specific. Recent studies on isolated cells and knockout mice depleted of PLC isozymes have revealed their distinct phenotypes. Given the specificity in distribution and cellular localization, it is clear that each PLC isozyme bears a unique function in the modulation of physiological responses. In this review, we discuss the structural organization, enzymatic properties and molecular diversity of PLC splicing variants and study functional and physiological roles of each isozyme.

  17. Stimulation and binding of myocardial phospholipase C by phosphatidic acid.

    PubMed

    Henry, R A; Boyce, S Y; Kurz, T; Wolf, R A

    1995-08-01

    Exposure of adult ventricular myocytes to exogenous natural phosphatidic acid results in the production of inositol phosphates by unknown mechanism(s). We characterized stimulation of myocytic phosphoinositide-specific phospholipase C (PLC) by synthetic dioleoyl phosphatidic acid (PA) as a potential mechanism for modulation of inositol phosphate production. Our data demonstrate that exogenous PA, at 10(-8)-10(-5) M, caused a concentration-dependent increase in inositol 1,4,5-trisphosphate in adult rabbit ventricular myocytes. PA also caused a concentration-dependent increase in in vitro activity of myocytic PLC in the presence or absence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). PLC-delta 1, the predominant isozyme of PLC expressed in adult rabbit ventricular myocytes, bound to liposomes of PA with high affinity in the presence of EGTA. The phosphomonoester group of PA was critical to in vitro stimulation of myocytic PLC activity and high-affinity binding of PLC-delta 1. We propose that binding of PLC-delta 1 to phosphatidic acid may be a novel mechanism for dynamic membrane association and modulation of PLC in adult ventricular myocytes.

  18. A comparative study of the clinical efficacy and safety of agomelatine with escitalopram in major depressive disorder patients: A randomized, parallel-group, phase IV study

    PubMed Central

    Urade, Chetan S.; Mahakalkar, Sunil M.; Tiple, Prashant G.

    2015-01-01

    Objective: To compare the efficacy of agomelatine with escitalopram in the treatment of major depressive disorder (MDD), improve sleep in MDD patients and study the adverse effects of agomelatine. Materials and Methods: Randomized, parallel-group, open-label study. The primary efficacy outcome was change from baseline to last post-baseline value in Hamilton depression rating scale and Leeds sleep evaluation questionnaire scale. Both parametric and nonparametric tests were applied for analysis. Results: Within-group and between-groups comparison of the mean HAMD17 scores showed statistically significant changes (P < 0.0001). Escitalopram showed early onset of response and remission compared to agomelatine at 10th week (P < 0.0001) and 14th week (P < 0.0001), respectively. In agomelatine, within-group and between-groups change of the mean LSEQ score was statistically significant at subsequent follow-up visits (P < 0.0001). Conclusion: Escitalopram is superior to agomelatine in efficacy, considering the early response, early remission, and better relief from symptoms of MDD in adults. Agomelatine may be preferred in MDD patients having insomnia as a predominant symptom. Liver function monitoring should be done in patients on long-term agomelatine therapy. PMID:26813706

  19. The Phospholipase D1 Pathway Modulates Macroautophagy

    PubMed Central

    Dall’Armi, Claudia; Hurtado-Lorenzo, Andres; Tian, Huasong; Morel, Etienne; Nezu, Akiko; Chan, Robin B.; Yu, W. Haung; Robinson, Kimberly S.; Yeku, Oladapo; Small, Scott A.; Duff, Karen; Frohman, Michael A.; Wenk, Markus R.; Yamamoto, Akitsugu; Di Paolo, Gilbert

    2012-01-01

    While macroautophagy is known to be an essential degradative process whereby autophagosomes mediate the engulfment and delivery of cytoplasmic components into lysosomes, the lipid changes underlying autophagosomal membrane dynamics are undetermined. Here we show that phospholipase D1 (PLD1), which is primarily associated with the endosomal system, partially relocalizes to the outer membrane of autophagosome-like structures upon nutrient starvation. The localization of PLD1, as well as the starvation-induced increase in PLD activity, are altered by wortmannin, a phosphatidylinositol 3-kinase inhibitor, suggesting PLD1 may act downstream of Vps34. Pharmacological inhibition of PLD and genetic ablation of PLD1 in the mouse decrease the starvation-induced expansion of LC3-positive compartments, consistent with a role of PLD1 in the regulation of autophagy. Furthermore, inhibition of PLD results in higher levels of tau and p62 aggregates in organotypic brain slices. Our in vitro and in vivo findings establish a novel role for PLD1 in autophagy. PMID:21266992

  20. Membrane associated phospholipase C from bovine brain

    SciTech Connect

    Lee, K.; Ryu, S.H.; Suh, P.; Choi, W.C.; Rhee, S.G.

    1987-05-01

    Cytosolic fractions of bovine brain contain 2 immunologically distinct phosphoinositide-specific phospholipase (PLC), PLC-I and PLC-II, whose MW are 150,000 and 145,000 respectively, under a denaturing condition. Monoclonal antibodies were derived against each form and specific radioimmunoassays were developed. Distribution of PLC-I and PLC-II in cytosolic and particulate fractions was measured using the radioimmunoassay. More than 90% of PLC-II was found in the cytosolic fraction, while the anti-PLC-I antibody cross-reacting protein was distributed nearly equally between the soluble fraction and the 2 M KCl extract of particulate fraction. The PLC enzyme in the particulate fraction was purified to homogeneity, yielding 2 proteins of 140 KDa and 150 KDa when analyzed on SDS-PAGE. Neither of the 2 enzymes cross-reacted with anti-PLC-II antibodies, but both could be immunoblotted by all 4 different anti-PLC-I antibodies. This suggests that the 140 KDa PLC was derived from the 150 KDa form. The 150 Kda form from particulate fraction was indistinguishable from the cytosolic PLC-I when their mixture was analyzed on SDS-PAGE. In addition, the elution profile of tryptic peptides derived from the 150 KDa particulate form was identical to that of cytosolic PLC-I. This result indicates that PLC-I is reversibly associated to membranes.

  1. Phosphatidylinositol-specific phospholipase C of Bacillus cereus: cloning, sequencing, and relationship to other phospholipases.

    PubMed Central

    Kuppe, A; Evans, L M; McMillen, D A; Griffith, O H

    1989-01-01

    The phosphatidylinositol (PI)-specific phospholipase C (PLC) of Bacillus cereus was cloned into Escherichia coli by using monoclonal antibody probes raised against the purified protein. The enzyme is specific for hydrolysis of the membrane lipid PI and PI-glycan-containing membrane anchors, which are important structural components of one class of membrane proteins. The protein expressed in E. coli comigrated with B. cereus PI-PLC in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, as detected by immunoblotting, and conferred PI-PLC activity on the host. This enzyme activity was inhibited by PI-PLC-specific monoclonal antibodies. The nucleotide sequence of the PI-PLC gene suggests that this secreted bacterial protein is synthesized as a larger precursor with a 31-amino-acid N-terminal extension to the mature enzyme of 298 amino acids. From analysis of coding and flanking sequences of the gene, we conclude that the PI-PLC gene does not reside next to the gene cluster of the other two secreted phospholipases C on the bacterial chromosome. The deduced amino acid sequence of the B. cereus PI-PLC contains a stretch of significant similarity to the glycosylphosphatidylinositol-specific PLC of Trypanosoma brucei. The conserved peptide is proposed to play a role in the function of these enzymes. Images PMID:2509427

  2. Validation of SCALE 4. 0 -- CSAS25 module and the 27-group ENDF/B-IV cross-section library for low-enriched uranium systems

    SciTech Connect

    Jordan, W.C.

    1993-02-01

    A version of KENO V.a and the 27-group library in SCALE-4.0 were validated for use in evaluating the nuclear criticality safety of low-enriched uranium systems. A total of 59 critical systems were analyzed. A statistical analysis of the results was performed, and subcritical acceptanced criteria are established.

  3. Validation of SCALE 4.0 -- CSAS25 module and the 27-group ENDF/B-IV cross-section library for low-enriched uranium systems

    SciTech Connect

    Jordan, W.C.

    1993-02-01

    A version of KENO V.a and the 27-group library in SCALE-4.0 were validated for use in evaluating the nuclear criticality safety of low-enriched uranium systems. A total of 59 critical systems were analyzed. A statistical analysis of the results was performed, and subcritical acceptanced criteria are established.

  4. Stalling autophagy: a new function for Listeria phospholipases

    PubMed Central

    Tattoli, Ivan; Sorbara, Matthew T.; Philpott, Dana J.; Girardin, Stephen E.

    2014-01-01

    Listeria monocytogenes is a Gram-positive bacterial pathogen that induces its own uptake in non-phagocytic cells. Following invasion, Listeria escapes from the entry vacuole through the secretion of a pore-forming toxin, listeriolysin O (LLO) that acts to damage and disrupt the vacuole membrane. Listeria then replicates in the cytosol and is able to spread from cell-to-cell using actin-based motility. In addition to LLO, Listeria produces two phospholipase toxins, a phosphatidylinositol-specific phospholipase C (PI-PLC, encoded by plcB) and a broad-range phospholipase C (PC-PLC, encoded by plcA), which contribute to bacterial virulence. It has long been recognized that secretion of PI- and PC-PLC enables the disruption of the double membrane vacuole during cell-to-cell spread, and those phospholipases have also been shown to augment LLO-dependent escape from the entry endosome. However, a specific role for Listeria phospholipases during the cytosolic stage of infection has not been previously reported. In a recent study, we demonstrated that Listeria PI-PLC and PC-PLC contribute to the bacterial escape from autophagy through a mechanism that involves direct inhibition of the autophagic flux in the infected cells [Tattoli et al. EMBO J (2013), 32, 3066-3078].

  5. Crystallization and preliminary X-ray diffraction analysis of myotoxin I, a Lys49-phospholipase A{sub 2} from Bothrops moojeni

    SciTech Connect

    Marchi-Salvador, D. P.; Silveira, L. B.; Soares, A. M.

    2005-10-01

    A new myotoxic Lys49-phospholipase from B. moojeni has been crystallized and X-ray diffraction data were collected to 2.18 Å resolution. Preliminary analysis indicates the presence of four molecules in the asymmetric unit, leading to a possible new oligomeric structure for Lys49-PLA{sub 2}s. A new myotoxic Lys49-phospholipase A{sub 2} isolated from Bothrops moojeni snake venom has been crystallized. The crystals diffracted to 2.18 Å resolution using a synchrotron-radiation source and belong to space group C2. The unit-cell parameters are a = 56.8, b = 125.0, c = 64.7 Å, β = 105.5°. Preliminary analysis indicates the presence of four molecules in the asymmetric unit. This may suggest a new quaternary structure for this Lys49-phospholipase A{sub 2} in contrast to the dimeric and monomeric structures solved so far for this class of proteins.

  6. Response to ``Comment on `Isotope effects in liquid water by infrared spectroscopy. IV. No free OH groups in liquid water''' [J. Chem. Phys. 135, 117101 (2011)

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Chapados, Camille

    2011-09-01

    The original infrared spectra in the OH stretch region that Riemenschneider and Ludwig (thereafter, RL) have obtained for pure water and aqueous salt solutions are very similar to what we have previously reported [J.-J. Max and C. Chapados, J. Chem. Phys. 115, 6803 (2001)]. In our 2010 paper, we claimed that "free" OH is not present in pure liquid water. The difference spectra from the salt solutions and pure water spectrum give small negative components situated near 3655 cm-1. Because this position is in the range where free OH groups should absorb RL assigned the negative peaks to free OH removed from pure water. That is, RL consider that pure liquid water contains free OH groups which are removed in the salt solutions. Obviously, the removal of all free OH present in pure water will produce maximum negative intensities in the difference spectra. In this response, we present unpublished difference spectra between several salt solutions and pure water where negative peaks are higher than that claimed by RL for pure water. Since this is impossible it demonstrates that the assignment proposed by RL to free OH is incorrect. The negative peaks come from the difference between large components that differ a little between salt solutions and pure water [J.-J. Max and C. Chapados, J. Chem. Phys. 115, 6803 (2001)]. Recall that the ionized salts do not absorb but perturb the surrounding water molecules.

  7. Crystal structure of human secretory phospholipase A2-IIA complex with the potent indolizine inhibitor 120-1032.

    PubMed

    Kitadokoro, K; Hagishita, S; Sato, T; Ohtani, M; Miki, K

    1998-04-01

    Phospholipase A2 is a key enzyme in a number of physiologically important cellular processes including inflammation and transmembrane signaling. Human secretory phospholipase A2-IIA is present at high concentrations in synovial fluid of patients with rheumatoid arthritis and in the plasma of patients with septic shock. Inhibitors of this enzyme have been suggested to be therapeutically useful non-steroidal anti-inflammatory drugs. The crystal structure of human secretory phospholipase A2-IIA bound to a novel potent indolizine inhibitor (120-1032) has been determined. The complex crystallizes in the space group P3121, with cell dimensions of a = b = 75.8 A and c = 51.3 A. The model was refined to an R-factor of 0. 183 for the intensity data collected to a resolution of 2.2 A. It was revealed that the inhibitor is located near the active site and bound to the calcium ion. Although the binding mode of the 120-1032 inhibitor to human secretory phospholipase A2-IIA is similar to that previously determined for an indole inhibitor LY311299, the specific interactions between the enzyme and the inhibitor in the present complex include the oxycarboxylate group which was introduced in this inhibitor. The oxycarboxylate group in 120-1032 is coordinated to the calcium ion and included in the water-mediated hydrogen bonding to the catalytic Asp49. In addition, the ethyl group in 120-1032 gains hydrophobic contacts with the cavity wall of the hydrophobic channel of the enzyme.

  8. Genetic ablation of calcium-independent phospholipase A2gamma leads to alterations in mitochondrial lipid metabolism and function resulting in a deficient mitochondrial bioenergetic phenotype.

    PubMed

    Mancuso, David J; Sims, Harold F; Han, Xianlin; Jenkins, Christopher M; Guan, Shao Ping; Yang, Kui; Moon, Sung Ho; Pietka, Terri; Abumrad, Nada A; Schlesinger, Paul H; Gross, Richard W

    2007-11-30

    Previously, we identified a novel calcium-independent phospholipase, designated calcium-independent phospholipase A(2) gamma (iPLA(2)gamma), which possesses dual mitochondrial and peroxisomal subcellular localization signals. To identify the roles of iPLA(2)gamma in cellular bioenergetics, we generated mice null for the iPLA(2)gamma gene by eliminating the active site of the enzyme through homologous recombination. Mice null for iPLA(2)gamma display multiple bioenergetic dysfunctional phenotypes, including 1) growth retardation, 2) cold intolerance, 3) reduced exercise endurance, 4) greatly increased mortality from cardiac stress after transverse aortic constriction, 5) abnormal mitochondrial function with a 65% decrease in ascorbate-induced Complex IV-mediated oxygen consumption, and 6) a reduction in myocardial cardiolipin content accompanied by an altered cardiolipin molecular species composition. We conclude that iPLA(2)gamma is essential for maintaining efficient bioenergetic mitochondrial function through tailoring mitochondrial membrane lipid metabolism and composition.

  9. Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (IV): Basic principles and parameters for MR imaging within the frame of image based adaptive cervix cancer brachytherapy

    PubMed Central

    Dimopoulos, Johannes C.A.; Petrow, Peter; Tanderup, Kari; Petric, Primoz; Berger, Daniel; Kirisits, Christian; Pedersen, Erik M.; van Limbergen, Erik; Haie-Meder, Christine; Pötter, Richard

    2012-01-01

    The GYN GEC-ESTRO working group issued three parts of recommendations and highlighted the pivotal role of MRI for the successful implementation of 3D image-based cervical cancer brachytherapy (BT). The main advantage of MRI as an imaging modality is its superior soft tissue depiction quality. To exploit the full potential of MRI for the better ability of the radiation oncologist to make the appropriate choice for the BT application technique and to accurately define the target volumes and the organs at risk, certain MR imaging criteria have to be fulfilled. Technical requirements, patient preparation, as well as image acquisition protocols have to be tailored to the needs of 3D image-based BT. The present recommendation is focused on the general principles of MR imaging for 3D image-based BT. Methods and parameters have been developed and progressively validated from clinical experience from different institutions (IGR, Universities of Vienna, Leuven, Aarhus and Ljubljana) and successfully applied during expert meetings, contouring workshops, as well as within clinical and interobserver studies. It is useful to perform pelvic MRI scanning prior to radiotherapy (“Pre-RT-MRI examination”) and at the time of BT (“BT MRI examination”) with one MR imager. Both low and high-field imagers, as well as both open and close magnet configurations conform to the requirements of 3D image-based cervical cancer BT. Multiplanar (transversal, sagittal, coronal and oblique image orientation) T2-weighted images obtained with pelvic surface coils are considered as the golden standard for visualisation of the tumour and the critical organs. The use of complementary MRI sequences (e.g. contrast-enhanced T1-weighted or 3D isotropic MRI sequences) is optional. Patient preparation has to be adapted to the needs of BT intervention and MR imaging. It is recommended to visualise and interpret the MR images on dedicated DICOM-viewer workstations, which should also assist the contouring

  10. Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (IV): Basic principles and parameters for MR imaging within the frame of image based adaptive cervix cancer brachytherapy.

    PubMed

    Dimopoulos, Johannes C A; Petrow, Peter; Tanderup, Kari; Petric, Primoz; Berger, Daniel; Kirisits, Christian; Pedersen, Erik M; van Limbergen, Erik; Haie-Meder, Christine; Pötter, Richard

    2012-04-01

    The GYN GEC-ESTRO working group issued three parts of recommendations and highlighted the pivotal role of MRI for the successful implementation of 3D image-based cervical cancer brachytherapy (BT). The main advantage of MRI as an imaging modality is its superior soft tissue depiction quality. To exploit the full potential of MRI for the better ability of the radiation oncologist to make the appropriate choice for the BT application technique and to accurately define the target volumes and the organs at risk, certain MR imaging criteria have to be fulfilled. Technical requirements, patient preparation, as well as image acquisition protocols have to be tailored to the needs of 3D image-based BT. The present recommendation is focused on the general principles of MR imaging for 3D image-based BT. Methods and parameters have been developed and progressively validated from clinical experience from different institutions (IGR, Universities of Vienna, Leuven, Aarhus and Ljubljana) and successfully applied during expert meetings, contouring workshops, as well as within clinical and interobserver studies. It is useful to perform pelvic MRI scanning prior to radiotherapy ("Pre-RT-MRI examination") and at the time of BT ("BT MRI examination") with one MR imager. Both low and high-field imagers, as well as both open and close magnet configurations conform to the requirements of 3D image-based cervical cancer BT. Multiplanar (transversal, sagittal, coronal and oblique image orientation) T2-weighted images obtained with pelvic surface coils are considered as the golden standard for visualisation of the tumour and the critical organs. The use of complementary MRI sequences (e.g. contrast-enhanced T1-weighted or 3D isotropic MRI sequences) is optional. Patient preparation has to be adapted to the needs of BT intervention and MR imaging. It is recommended to visualise and interpret the MR images on dedicated DICOM-viewer workstations, which should also assist the contouring

  11. Effect of Darapladib Treatment on Endarterectomy Carotid Plaque Lipoprotein-Associated Phospholipase A2 Activity: A Randomized, Controlled Trial

    PubMed Central

    Johnson, Joel L.; Shi, Yi; Snipes, Rose; Janmohamed, Salim; Rolfe, Timothy E.; Davis, Bill; Postle, Anthony; Macphee, Colin H.

    2014-01-01

    Background The aim of this study was to assess the effects of darapladib, a selective oral investigational lipoprotein-associated phospholipase A2 inhibitor, on both plasma and plaque lipoprotein-associated phospholipase A2 activity. Methods Patients undergoing elective carotid endarterectomy were randomized to darapladib 40 mg (n = 34), 80 mg (n = 34), or placebo (n = 34) for 14 days, followed by carotid endarterectomy 24 hours after the last dose of study medication. Results Darapladib 40 mg and 80 mg reduced plasma lipoprotein-associated phospholipase A2 activity by 52% and 81%, respectively, versus placebo (both P<0.001). Significant reductions in plaque lipoprotein-associated phospholipase A2 activity were also observed compared with placebo (P<0.0001), which equated to a 52% and 80% decrease compared with placebo. No significant differences were observed between groups in plaque lysophosphatidylcholine content or other biomarkers, although a dose-dependent decrease in plaque matrix metalloproteinase-9 mRNA expression was observed with darapladib 80 mg (P = 0.053 vs placebo). In a post-hoc analysis, plaque caspase-3 (P<0.001) and caspase-8 (P<0.05) activity were found to be significantly lower in the darapladib 80-mg group versus placebo. No major safety concerns were identified in the study. Conclusions Short-term treatment (14±4 days) with darapladib produced a robust, dose-dependent reduction in plasma lipoprotein-associated phospholipase A2 activity. More importantly, darapladib demonstrated placebo-corrected reductions in carotid plaque lipoprotein-associated phospholipase A2 activity of similar magnitude. Darapladib was generally well tolerated and no safety concerns were identified. Additional studies of longer duration are needed to explore whether these pharmacodynamic effects are associated with improved clinical outcomes, as might be hypothesized. Trial Registration Information Name of Registry 1: ClinicalTrials.gov Registry Number

  12. Rapid activation of specific phospholipase(s) D by cytokinin in Amaranthus assay system.

    PubMed

    Kravets, Volodymir S; Kolesnikov, Yaroslav S; Kretynin, Sergey V; Getman, Irina A; Romanov, Georgy A

    2010-03-01

    The suggested link between intracellular cytokinin signaling and phospholipase D (PLD, EC 3.1.4.4.) activity (Romanov et al. 2000, 2002) was investigated. The activity of PLD in the early period of cytokinin action was studied in vivo in derooted Amaranthus caudatus seedlings, using the level of phosphatidylbutanol production as a measure of PLD activity. Rapid activation of phosphatidylbutanol synthesis was demonstrated as early as within 5 min of cytokinin administration. Neomycin, a known phosphatidylinositol-4,5-bisphosphate (PIP(2)) antagonist, strongly repressed both physiological cytokinin effect and cytokinin-dependent PLD activation. N-acylethanolamine (NAE 12), an inhibitor of alpha-class PLD, did not influence significantly cytokinin effect on Amaranthus seedlings. Together, results suggest the involvement of PIP(2)-dependent non-class alpha-PLD in the molecular mechanism of cytokinin action.

  13. Genomics:GTL Contractor-Grantee Workshop IV and Metabolic Engineering Working Group Inter-Agency Conference on Metabolic Engineering 2006

    SciTech Connect

    Mansfield, Betty Kay; Martin, Sheryl A

    2006-02-01

    Welcome to the 2006 joint meeting of the fourth Genomics:GTL Contractor-Grantee Workshop and the six Metabolic Engineering Working Group Inter-Agency Conference. The vision and scope of the Genomics:GTL program continue to expand and encompass research and technology issues from diverse scientific disciplines, attracting broad interest and support from researchers at universities, DOE national laboratories, and industry. Metabolic engineering's vision is the targeted and purposeful alteration of metabolic pathways to improve the understanding and use of cellular pathways for chemical transformation, energy transduction, and supramolecular assembly. These two programs have much complementarity in both vision and technological approaches, as reflected in this joint workshop. GLT's challenge to the scientific community remains the further development and use of a broad array of innovative technologies and computational tools to systematically leverage the knowledge and capabilities brought to us by DNA sequencing projects. The goal is to seek a broad and predictive understanding of the functioning and control of complex systems--individual microbes, microbial communities, and plants. GTL's prominent position at the interface of the physical, computational, and biological sciences is both a strength and challenge. Microbes remain GTL's principal biological focus. In the complex 'simplicity' of microbes, they find capabilities needed by DOE and the nation for clean and secure energy, cleanup of environmental contamination, and sequestration of atmospheric carbon dioxide that contributes to global warming. An ongoing challenge for the entire GTL community is to demonstrate that the fundamental science conducted in each of your research projects brings us a step closer to biology-based solutions for these important national energy and environmental needs.

  14. Intelligent Virtual Station (IVS)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Intelligent Virtual Station (IVS) is enabling the integration of design, training, and operations capabilities into an intelligent virtual station for the International Space Station (ISS). A viewgraph of the IVS Remote Server is presented.

  15. Calcium-independent phospholipases A2 and their roles in biological processes and diseases

    PubMed Central

    Ramanadham, Sasanka; Ali, Tomader; Ashley, Jason W.; Bone, Robert N.; Hancock, William D.; Lei, Xiaoyong

    2015-01-01

    Among the family of phospholipases A2 (PLA2s) are the Ca2+-independent PLA2s (iPLA2s) and they are designated group VI iPLA2s. In relation to secretory and cytosolic PLA2s, the iPLA2s are more recently described and details of their expression and roles in biological functions are rapidly emerging. The iPLA2s or patatin-like phospholipases (PNPLAs) are intracellular enzymes that do not require Ca2+ for activity, and contain lipase (GXSXG) and nucleotide-binding (GXGXXG) consensus sequences. Though nine PNPLAs have been recognized, PNPLA8 (membrane-associated iPLA2γ) and PNPLA9 (cytosol-associated iPLA2β) are the most widely studied and understood. The iPLA2s manifest a variety of activities in addition to phospholipase, are ubiquitously expressed, and participate in a multitude of biological processes, including fat catabolism, cell differentiation, maintenance of mitochondrial integrity, phospholipid remodeling, cell proliferation, signal transduction, and cell death. As might be expected, increased or decreased expression of iPLA2s can have profound effects on the metabolic state, CNS function, cardiovascular performance, and cell survival; therefore, dysregulation of iPLA2s can be a critical factor in the development of many diseases. This review is aimed at providing a general framework of the current understanding of the iPLA2s and discussion of the potential mechanisms of action of the iPLA2s and related involved lipid mediators. PMID:26023050

  16. Ovarian Cancer Stage IV

    MedlinePlus

    ... hyphen, e.g. -historical Searches are case-insensitive Ovarian Cancer Stage IV Add to My Pictures View /Download : ... 1200x1335 View Download Large: 2400x2670 View Download Title: Ovarian Cancer Stage IV Description: Drawing of stage IV shows ...

  17. Persistent improved results after adding vincristine and bleomycin to a cyclophosphamide/hydroxorubicin/Vm-26/prednisone combination (CHVmP) in stage III-IV intermediate- and high-grade non-Hodgkin's lymphoma. The EORTC Lymphoma Cooperative Group.

    PubMed

    Meerwaldt, J H; Carde, P; Somers, R; Thomas, J; Kluin-Nelemans, J C; Bron, D; Noordijk, E M; Cosset, J M; Bijnens, L; Teodorovic, I; Hagenbeek, A

    1997-01-01

    CHOP has been and still is regarded by many as the 'standard' treatment of advanced non-Hodgkin's lymphoma. In 1980 the EORTC Lymphoma Cooperative Group started a study to evaluate the addition of vincristine and bleomycin to its standard four-drug combination chemotherapy, CHVmP (cyclophosphamide, hydroxorubicin, Vm-26, prednisone). Eligible patients were stage III or IV, intermediate- to high-grade non-Hodgkin's lymphoma (Working Formulation E-I). One-hundred-eighty-nine patients were entered, of whom 140 were eligible and evaluable. A previous report showed an improved response rate and failure-free survival (FFS) and overall survival for the combination CHVmP-VB. At ten years, the outcome still favors the addition of vincristine and bleomycin. The FFS was 34% vs. 23% and the overall survival 34% vs 22%. This difference was mainly due to a difference in CR rate (74% vs. 49%), Relapse-free survival for patients reaching a CR was the same in both arms. When the patients were grouped according to the International Prognostic Factor Index, no statistically significant difference could be observed in favor of one treatment within either group. This trial clearly demonstrates the benefit gained by the addition of vincristine and bleomycin to 'standard' chemotherapy for intermediate and high-grade non-Hodgkin's lymphoma.

  18. Biochemical Characterization, Action on Macrophages, and Superoxide Anion Production of Four Basic Phospholipases A2 from Panamanian Bothrops asper Snake Venom

    PubMed Central

    Rueda, Aristides Quintero; Rodríguez, Isela González; Arantes, Eliane C.; Setúbal, Sulamita S.; Calderon, Leonardo de A.; Zuliani, Juliana P.; Stábeli, Rodrigo G.; Soares, Andreimar M.

    2013-01-01

    Bothrops asper (Squamata: Viperidae) is the most important venomous snake in Central America, being responsible for the majority of snakebite accidents. Four basic PLA2s (pMTX-I to -IV) were purified from crude venom by a single-step chromatography using a CM-Sepharose ion-exchange column (1.5 × 15 cm). Analysis of the N-terminal sequence demonstrated that pMTX-I and III belong to the catalytically active Asp49 phospholipase A2 subclass, whereas pMTX-II and IV belong to the enzymatically inactive Lys49 PLA2s-like subclass. The PLA2s isolated from Panama Bothrops asper venom (pMTX-I, II, III, and IV) are able to induce myotoxic activity, inflammatory reaction mainly leukocyte migration to the muscle, and induce J774A.1 macrophages activation to start phagocytic activity and superoxide production. PMID:23509779

  19. Group IV mid-infrared photonics

    NASA Astrophysics Data System (ADS)

    Mashanovich, G. Z.; Nedeljkovic, M.; Soler Penades, J.; Mitchell, C. J.; Khokhar, A. Z.; Littlejohns, C. J.; Stankovic, S.; Troia, B.; Wang, Y.; Reynolds, S.; Passaro, V. M. N.; Shen, L.; Healy, N.; Peacock, A. C.; Alonso-Ramos, C.; Ortega-Monux, A.; Wanguemert-Perez, G.; Molina-Fernandez, I.; Rowe, D. J.; Wilkinson, J. S.; Cheben, P.; Ackert, J. J.; Knights, A. P.; Thomson, D. J.; Gardes, F. Y.

    2015-02-01

    In this paper we present SOI, suspended Si, and Ge-on-Si photonic platforms and devices for the mid-infrared. We demonstrate low loss strip and slot waveguides in SOI and show efficient strip-slot couplers. A Vernier configuration based on racetrack resonators in SOI has been also investigated. Mid-infrared detection using defect engineered silicon waveguides is reported at the wavelength of 2-2.5 μm. In order to extend transparency of Si waveguides, the bottom oxide cladding needs to be removed. We report a novel suspended Si design based on subwavelength structures that is more robust than previously reported suspended designs. We have fabricated record low loss Ge-on-Si waveguides, as well as several other passive devices in this platform. All optical modulation in Ge is also analyzed.

  20. Alternative Approaches to Group IV Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Snedaker, Matthew Loren

    In the pursuit of energy efficiency, there is a demand for systems capable of recovering waste heat. A temperature gradient across a thermoelectric material results in the thermal diffusion of charge carriers from the hot side to the cold side, giving rise to a voltage that can be used to convert waste heat to electricity. Silicon germanium (SiGe) alloys are the standard materials used for thermoelectric generators at high temperatures. We report an alternative method for preparing p-type Si1- xGex alloys from a boron-doped silica-germania nanocomposite. This is the first demonstration of the thermoelectric properties of SiGe-based thermoelectrics prepared at temperatures below the alloy's melting point through a magnesiothermic reduction of the (SiO 2)1-x(GeO2) x. We observe a thermoelectric power factor that is competitive with the literature record for the conventionally prepared SiGe. The large grain size in our hot pressed SiGe limits the thermoelectric figure of merit to 0.5 at 800°C for an optimally doped p-type Si80Ge 20 alloy. A phosphorus-doped oxide can yield n-type Si1- xGex; however, the current processing method introduces a background boron content that compensates ~10% of the donor impurities and limits the thermoelectric power factor. Spark plasma sintering of the nano-Si1-xGe x yields a heterogeneous alloy with thermal conductivity lower than that of the hot pressed homogeneous alloy due to a reduction in the average crystallite size. Magnesiothermic reduction in the presence of molten salts allows some control over crystallite growth and the extent of Si-Ge alloying.

  1. Mechanism of inhibition of human secretory phospholipase A2 by flavonoids: rationale for lead design

    NASA Astrophysics Data System (ADS)

    Lättig, Jens; Böhl, Markus; Fischer, Petra; Tischer, Sandra; Tietböhl, Claudia; Menschikowski, Mario; Gutzeit, Herwig O.; Metz, Peter; Pisabarro, M. Teresa

    2007-08-01

    The human secretory phospholipase A2 group IIA (PLA2-IIA) is a lipolytic enzyme. Its inhibition leads to a decrease in eicosanoids levels and, thereby, to reduced inflammation. Therefore, PLA2-IIA is of high pharmacological interest in treatment of chronic diseases such as asthma and rheumatoid arthritis. Quercetin and naringenin, amongst other flavonoids, are known for their anti-inflammatory activity by modulation of enzymes of the arachidonic acid cascade. However, the mechanism by which flavonoids inhibit Phospholipase A2 (PLA2) remained unclear so far. Flavonoids are widely produced in plant tissues and, thereby, suitable targets for pharmaceutical extractions and chemical syntheses. Our work focuses on understanding the binding modes of flavonoids to PLA2, their inhibition mechanism and the rationale to modify them to obtain potent and specific inhibitors. Our computational and experimental studies focused on a set of 24 compounds including natural flavonoids and naringenin-based derivatives. Experimental results on PLA2-inhibition showed good inhibitory activity for quercetin, kaempferol, and galangin, but relatively poor for naringenin. Several naringenin derivatives were synthesized and tested for affinity and inhibitory activity improvement. 6-(1,1-dimethylallyl)naringenin revealed comparable PLA2 inhibition to quercetin-like compounds. We characterized the binding mode of these compounds and the determinants for their affinity, selectivity, and inhibitory potency. Based on our results, we suggest C(6) as the most promising position of the flavonoid scaffold to introduce chemical modifications to improve affinity, selectivity, and inhibition of PLA2-IIA by flavonoids.

  2. Substituted thiobenzoic acid S-benzyl esters as potential inhibitors of a snake venom phospholipase A2: Synthesis, spectroscopic and computational studies

    NASA Astrophysics Data System (ADS)

    Henao Castañeda, I. C.; Pereañez, J. A.; Jios, J. L.

    2012-11-01

    4-Chlorothiobenzoic acid S-benzyl ester (I), 3-nitrothiobenzoic acid S-benzyl ester (II), 4-nitrothiobenzoic acid S-benzyl ester (III) and 4-methylthiobenzoic acid S-benzyl ester (IV) were prepared and characterized by 1H and 13C NMR, Mass spectrometry and IR spectroscopy. Quantum chemical calculations were performed with Gaussian 09 to calculate the geometric parameters and vibrational spectra. Phospholipase A2 (PLA2) was purified from Crotalus durissus cumanensis venom by molecular exclusion chromatography, followed by reverse phase-high performance liquid chromatography. Two studies of the inhibition of phospholipase A2 activity were performed using phosphatidilcholine and 4-nitro-3-octanoyloxybenzoic acid as substrates, in both cases compound II showed the best inhibitory ability, with 74.89% and 69.91% of inhibition, respectively. Average percentage of inhibition was 52.49%. Molecular docking was carried out with Autodock Vina using as ligands the minimized structures of compounds (I-IV) and as protein PLA2 (PDB code 2QOG). The results suggest that compounds I-IV could interact with His48 at the active site of PLA2. In addition, all compounds showed Van der Waals interactions with residues from hydrophobic channel of the enzyme. This interaction would impede normal catalysis cycle of the PLA2.

  3. Role of Inositol Phosphosphingolipid Phospholipase C1, the Yeast Homolog of Neutral Sphingomyelinases in DNA Damage Response and Diseases.

    PubMed

    Tripathi, Kaushlendra

    2015-01-01

    Sphingolipids play a very crucial role in many diseases and are well-known as signaling mediators in many pathways. Sphingolipids are produced during the de novo process in the ER (endoplasmic reticulum) from the nonsphingolipid precursor and comprise both structural and bioactive lipids. Ceramide is the central core of the sphingolipid pathway, and its production has been observed following various treatments that can induce several different cellular effects including growth arrest, DNA damage, apoptosis, differentiation, and senescence. Ceramides are generally produced through the sphingomyelin hydrolysis and catalyzed by the enzyme sphingomyelinase (SMase) in mammals. Presently, there are many known SMases and they are categorized into three groups acid SMases (aSMases), alkaline SMases (alk-SMASES), and neutral SMases (nSMases). The yeast homolog of mammalians neutral SMases is inositol phosphosphingolipid phospholipase C. Yeasts generally have inositol phosphosphingolipids instead of sphingomyelin, which may act as a homolog of mammalian sphingomyelin. In this review, we shall explain the structure and function of inositol phosphosphingolipid phospholipase C1, its localization inside the cells, mechanisms, and its roles in various cell responses during replication stresses and diseases. This review will also give a new basis for our understanding for the mechanisms and nature of the inositol phosphosphingolipid phospholipase C1/nSMase.

  4. Interaction of a trehalose lipid biosurfactant produced by Rhodococcus erythropolis 51T7 with a secretory phospholipase A2.

    PubMed

    Zaragoza, Ana; Teruel, José A; Aranda, Francisco J; Ortiz, Antonio

    2013-10-15

    Trehalose-containing glycolipid biosurfactants form an emerging group of interesting compounds, which alter the structure and properties of phospholipid membranes, and interact with enzymatic and non-enzymatic proteins. Phospholipases A2 constitute a class of enzymes that hydrolyze the sn-2 ester of glycerophospholipids, and are classified into secreted phospholipases A2 (sPLA2) and intracellular phospholipases A2. In this work, pancreatic sPLA2 was chosen as a model enzyme to study the effect of the trehalose lipid biosurfactant on enzymes acting on interfaces. By using this enzyme, it is possible to study the modulation of enzyme activity, either by direct interaction of the biosurfactant with the protein, or as a result of the incorporation of the glycolipid on the phospholipid target membrane. It is shown that the succinoyl trehalose lipid isolated from Rhodococcus erythropolis 51T7 interacts with porcine pancreatic sPLA2 and inhibits its catalytic activity. Two modes of inhibition are observed, which are clearly differentiated by its timescale. First, a slow inhibition of sPLA2 activity upon preincubation of the enzyme with trehalose lipid in the absence of substrate is described. Second, incorporation of trehalose lipid into the phospholipid target membrane gives rise to a fast enzyme inhibition. These results are discussed in the light of previous data on sPLA2 inhibitors and extend the list of interesting biological activities reported for this R. erythropolis trehalose lipid biosurfactant.

  5. Energy levels and lifetimes of Nd IV, Pm IV, Sm IV, and Eu IV

    SciTech Connect

    Dzuba, V. A.; Safronova, U. I.; Johnson, W. R.

    2003-09-01

    To address the shortage of experimental data for electron spectra of triply ionized rare-earth elements we have calculated energy levels and lifetimes of 4f{sup n+1} and 4f{sup n}5d configurations of Nd IV (n=2), Pm IV (n=3), Sm IV (n=4), and Eu IV (n=5) using Hartree-Fock and configuration-interaction methods. To control the accuracy of our calculations we also performed similar calculations for Pr III, Nd III, and Sm III, for which experimental data are available. The results are important, in particular, for physics of magnetic garnets.

  6. Molecular cloning of phospholipases A(2) from venom glands of Echis carpet vipers.

    PubMed

    Bharati, K; Hasson, S S; Oliver, J; Laing, G D; Theakston, R D G; Harrison, R A

    2003-06-01

    Venom toxin-specific antibodies offer a more rational treatment of snake envenoming than conventional antivenom. Here, we describe novel cDNAs encoding phospholipase A(2) (PLA(2)) isoforms from venom gland RNA of Echis pyramidum leakeyi (Epl), Echis sochureki (Es) and Echis ocellatus (Eo). The deduced amino acid sequences of these cDNAs encoded proteins with high overall sequence identity to the viper group II PLA(2) protein family, including the 14 cysteine residues capable of forming seven disulphide bonds that characterize this group of PLA(2) enzymes. Comparison of the PLA(2) sequences from Echis with those from related vipers failed to make significant geographic, taxonomic or PLA(2)-function distinctions between these Echis PLA(2) isoforms. However, their deduced hydrophilicity profiles revealed a conserved tertiary structure that we will exploit, by epidermal DNA immunization, to generate PLA(2)-neutralizing antibodies with polyspecific potential.

  7. A fully integrated high-throughput screening methodology for the discovery of new polyolefin catalysts: discovery of a new class of high temperature single-site group (IV) copolymerization catalysts.

    PubMed

    Boussie, Thomas R; Diamond, Gary M; Goh, Christopher; Hall, Keith A; LaPointe, Anne M; Leclerc, Margarete; Lund, Cheryl; Murphy, Vince; Shoemaker, James A W; Tracht, Ursula; Turner, Howard; Zhang, Jessica; Uno, Tetsuo; Rosen, Robert K; Stevens, James C

    2003-04-09

    For the first time, new catalysts for olefin polymerization have been discovered through the application of fully integrated high-throughput primary and secondary screening techniques supported by rapid polymer characterization methods. Microscale 1-octene primary screening polymerization experiments combining arrays of ligands with reactive metal complexes M(CH(2)Ph)(4) (M = Zr, Hf) and multiple activation conditions represent a new high-throughput technique for discovering novel group (IV) polymerization catalysts. The primary screening methods described here have been validated using a commercially relevant polyolefin catalyst, and implemented rapidly to discover the new amide-ether based hafnium catalyst [eta(2)-(N,O)[bond](2-MeO[bond]C(6)H(4))(2,4,6-Me(3)C(6)H(2))N]Hf(CH(2)Ph)(3) (1), which is capable of polymerizing 1-octene to high conversion. The molecular structure of 1 has been determined by X-ray diffraction. Larger scale secondary screening experiments performed on a focused 96-member amine-ether library demonstrated the versatile high temperature ethylene-1-octene copolymerization capabilities of this catalyst class, and led to significant performance improvements over the initial primary screening discovery. Conventional one gallon batch reactor copolymerizations performed using selected amide-ether hafnium compounds confirmed the performance features of this new catalyst class, serving to fully validate the experimental results from the high-throughput approaches described herein.

  8. Effects of Estradiol and Progesterone on Rat Intestinal and Hepatic Phospholipase A Activity

    DTIC Science & Technology

    1988-12-01

    intestine and liver play Major roles in lipid and lipoprotein metabolism. Both rgans contain high activities of phospholipase A, but little is known... Phospholipase A is involved in the initial step in prostaglandin synthesis (1) and may also play a role in the metabolism of plasma lipoproteins (2...and subcellular fraction. Phospholipase A (EC 3.1.1.32 and 3.1.1.4, A, - A2 ) activity was determined in these acetone powders by the method of

  9. Signalling through phospholipase C interferes with clathrin-mediated endocytosis.

    PubMed

    Carvou, Nicolas; Norden, Anthony G W; Unwin, Robert J; Cockcroft, Shamshad

    2007-01-01

    We investigated if phosphatidylinositol(4,5)bisphosphate (PtdIns(4,5)P2) hydrolysis by phospholipase C activation through cell surface receptors would interfere with clathrin-mediated endocytosis as recruitment of clathrin assembly proteins is PtdIns(4,5)P2-dependent. In the WKPT renal epithelial cell line, endocytosed insulin and beta2-glycoprotein I (beta2gpI) were observed in separate compartments, although endocytosis of both ligands was clathrin-dependent as demonstrated by expression of the clathrin-binding C-terminal domain of AP180 (AP180-C). The two uptake mechanisms were different as only insulin uptake was reduced when the mu2-subunit of the adaptor complex AP-2 was silenced by RNA interference. ATP receptors are expressed at the apical surface of renal cells and, thus, we examined the effect of extracellular ATP on insulin and beta2gpI uptake. ATP stimulated phospholipase C activity, and also suppressed uptake of insulin, but not beta2gpI. This effect was reversed by the PLC inhibitor U-73122. In polarized cell cultures, insulin uptake was apical, whereas beta2gpI uptake was through the basolateral membrane, thus providing an explanation for selective inhibition of insulin endocytosis by ATP. Taken together, these results demonstrate that stimulation of apical G-protein-coupled P2Y receptors, which are coupled to phospholipase C activation diminishes clathrin-mediated endocytosis without interfering with basolateral endocytic mechanisms.

  10. Phosphatidylinositol Specific Phospholipase C of Plant Stems 1

    PubMed Central

    Pfaffmann, Helmut; Hartmann, Elmar; Brightman, Andrew O.; Morré, D. James

    1987-01-01

    A phosphatidylinositol-specific phospholipase C of plant stems (EC 3.1.4.10) assayed at pH 6.6 and at 30°C cleaved phosphatidylinositol such that more than 85% of the product was inositol-1-phosphate. Other phospholipids were cleaved 5 to 10% or less under these conditions. The phospholipase had both a soluble and a membrane-associated form. The soluble activity accounted for approximately 85 to 90% of the activity and 15% was associated with membranes. The membrane-associated activity was most concentrated in the plasma membranes of hypocotyl segments of both soybean (Glycine max) and bushbean (Phaseolus vulgaris). The plasma membrane location was verified by analysis of highly purified plasma membranes prepared both by aqueous two-phase partitioning and by preparative free-flow electrophoresis and from the quantitation of the activity in all major cell fractions. Internal membranes also contained phospholipase C activity but at specific activity levels of about 0.1 those present in plasma membranes. Golgi apparatus-enriched fractions from which plasma membrane contaminants were removed by two-phase partition contained the activity at specific activity levels 0.2 those of plasma membrane. Both the soluble and the membrane-associated activity was stimulated by calcium but not by calmodulin, either alone or in the presence of calcium. PMID:16665820

  11. Phosphoinositide-specific phospholipase C in health and disease.

    PubMed

    Cocco, Lucio; Follo, Matilde Y; Manzoli, Lucia; Suh, Pann-Ghill

    2015-10-01

    Phospholipases are widely occurring and can be found in several different organisms, including bacteria, yeast, plants, animals, and viruses. Phospholipase C (PLC) is a class of phospholipases that cleaves phospholipids on the diacylglycerol (DAG) side of the phosphodiester bond producing DAGs and phosphomonoesters. Among PLCs, phosphoinositide-specific PLC (PI-PLC) constitutes an important step in the inositide signaling pathways. The structures of PI-PLC isozymes show conserved domains as well as regulatory specific domains. This is important, as most PI-PLCs share a common mechanism, but each of them has a peculiar role and can have a specific cell distribution that is linked to a specific function. More importantly, the regulation of PLC isozymes is fundamental in health and disease, as there are several PLC-dependent molecular mechanisms that are associated with the activation or inhibition of important physiopathological processes. Moreover, PI-PLC alternative splicing variants can play important roles in complex signaling networks, not only in cancer but also in other diseases. That is why PI-PLC isozymes are now considered as important molecules that are essential for better understanding the molecular mechanisms underlying both physiology and pathogenesis, and are also potential molecular targets useful for the development of innovative therapeutic strategies.

  12. Endogenous phospholipase A2 inhibitors in snakes: a brief overview.

    PubMed

    Campos, Patrícia Cota; de Melo, Lutiana Amaral; Dias, Gabriel Latorre Fortes; Fortes-Dias, Consuelo Latorre

    2016-01-01

    The blood plasma of numerous snake species naturally comprises endogenous phospholipase A2 inhibitors, which primarily neutralize toxic phospholipases A2 that may eventually reach their circulation. This inhibitor type is generally known as snake blood phospholipase A2 inhibitors (sbPLIs). Most, if not all sbPLIs are oligomeric glycosylated proteins, although the carbohydrate moiety may not be essential for PLA2 inhibition in every case. The presently known sbPLIs belong to one of three structural classes - namely sbαPLI, sbβPLI or sbγPLI - depending on the presence of characteristic C-type lectin-like domains, leucine-rich repeats or three-finger motifs, respectively. Currently, the most numerous inhibitors described in the literature are sbαPLIs and sbγPLIs, whereas sbβPLIs are rare. When the target PLA2 is a Lys49 homolog or an Asp49 myotoxin, the sbPLI is denominated a myotoxin inhibitor protein (MIP). In this brief overview, the most relevant data on sbPLIs will be presented. Representative examples of sbαPLIs and sbγPLIs from two Old World - Gloydius brevicaudus and Malayopython reticulatus - and two New World - Bothrops alternatus and Crotalus durissus terrificus - snake species will be emphasized.

  13. Synthesis and structure of ruthenium(IV) complexes featuring N-heterocyclic ligands with an N-H group as the hydrogen-bond donor: hydrogen interactions in solution and in the solid state.

    PubMed

    Díez, Josefina; Gimeno, José; Merino, Isabel; Rubio, Eduardo; Suárez, Francisco J

    2011-06-06

    The synthesis and characterization of novel ruthenium(IV) complexes [Ru(η(3):η(3)-C(10)H(16))Cl(2)L] [L = 3-methylpyrazole (2b), 3,5-dimethylpyrazole (2c), 3-methyl-5-phenylpyrazole (2d), 2-(1H-pyrazol-5-yl)phenol (2e), 6-azauracile (3), and 1H-indazol-3-ol (4)] are reported. Complex 2e is converted to the chelated complex [Ru(η(3):η(3)-C(10)H(16))Cl(κ(2)-N,O-2-(1H-pyrazol-3-yl)phenoxy)] (5) by treatment with an excess of NaOH. All of the ligands feature N-H, O-H, or C═O as the potential hydrogen-bonding group. The structures of complexes 2a-2c, 2e, 3, and 5 in the solid state have been determined by X-ray diffraction. Complexes 2a-2c and 3, which contain the pyrazole N-H group, exhibit intra- and intermolecular hydrogen bonds with chloride ligands [N-H···Cl distances (Å): intramolecular, 2.30-2.78; intermolecular, 2.59-2.77]. Complexes 2e and 3 bearing respectively O-H and C═O groups also feature N-H···O interactions [intramolecular (2e), 2.27 Å; intermolecular (3), 2.00 Å]. Chelated complex 5, lacking the O-H group, only shows an intramolecular N-H···Cl hydrogen bonding of 2.42 Å. The structure of complex 3, which turns out to be a dimer in the solid state through a double intermolecular N-H···O hydrogen bonding, has also been investigated in solution (CD(2)Cl(2)) by NMR diffusion studies. Diffusion-ordered spectroscopy experiments reveal an equilibrium between monomer and dimer species in solution whose extension depends on the temperature, concentration, and coordinating properties of the solvent. Preliminary catalytic studies show that complex 3 is highly active in the redox isomerization of the allylic alcohols in an aqueous medium under very mild reaction conditions (35 °C) and in the absence of a base.

  14. Secretory phospholipases A2 induce neurite outgrowth in PC12 cells.

    PubMed Central

    Nakashima, Satoru; Ikeno, Yutaka; Yokoyama, Tatsuya; Kuwana, Masakazu; Bolchi, Angelo; Ottonello, Simone; Kitamoto, Katsuhiko; Arioka, Manabu

    2003-01-01

    sPLA(2)s (secretory phospholipases A(2)) belong to a broad and structurally diverse family of enzymes that hydrolyse the sn -2 ester bond of glycerophospholipids. We previously showed that a secreted fungal 15 kDa protein, named p15, as well as its orthologue from Streptomyces coelicolor (named Scp15) induce neurite outgrowth in PC12 cells at nanomolar concentrations. We report here that both p15 and Scp15 are members of a newly identified group of fungal/bacterial sPLA(2)s. The phospholipid-hydrolysing activity of p15 is absolutely required for neurite outgrowth induction. Mutants with a reduced PLA(2) activity exhibited a comparable reduction in neurite-inducing activity, and the ability to induce neurites closely matched the capacity of various p15 forms to promote fatty acid release from live PC12 cells. A structurally divergent member of the sPLA(2) family, bee venom sPLA(2), also induced neurites in a phospholipase activity-dependent manner, and the same effect was elicited by mouse group V and X sPLA(2)s, but not by group IB and IIA sPLA(2)s. Lysophosphatidylcholine, but not other lysophospholipids, nor arachidonic acid, elicited neurite outgrowth in an L-type Ca(2+) channel activity-dependent manner. In addition, p15-induced neuritogenesis was unaffected by various inhibitors that block arachidonic acid conversion into bioactive eicosanoids. Altogether, these results delineate a novel, Ca(2+)- and lysophosphatidylcholine-dependent neurotrophin-like role of sPLA(2)s in the nervous system. PMID:12967323

  15. 2-aminohydroxamic acid derivatives as inhibitors of Bacillus cereus phosphatidylcholine preferred phospholipase C PC-PLC(Bc).

    PubMed

    González-Bulnes, Patricia; González-Roura, Albert; Canals, Daniel; Delgado, Antonio; Casas, Josefina; Llebaria, Amadeu

    2010-12-15

    Phosphatidylcholine preferring phospholipase C (PC-PLC) is an important enzyme that plays a key role in a variety of cellular events and lipid homoeostases. Bacillus cereus phospholipase C (PC-PLC(Bc)) has antigenic similarity with the elusive mammalian PC-PLC, which has not thus far been isolated and purified. Therefore the discovery of inhibitors of PC-PLC(Bc) is of current interest. Here, we describe the synthesis and biological evaluation of a new type of compounds inhibiting PC-PLC(Bc). These compounds have been designed by evolution of previously described 2-aminohydroxamic acid PC-PLC(Bc) inhibitors that block the enzyme by coordination of the zinc active site atoms present in PC-PLC(Bc) [Gonzalez-Roura, A.; Navarro, I.; Delgado, A.; Llebaria, A.; Casas, J. Angew. Chem. Int. Ed.2004, 43, 862]. The new compounds maintain the zinc coordinating groups and possess an extra trimethylammonium function, linked to the hydroxyamide nitrogen by an alkyl chain, which is expected to mimic the trimethylammonium group of the phosphatidylcholine PC-PLC(Bc) substrates. Some of the compounds described inhibit the enzyme with IC(50)'s in the low micromolar range. Unexpectedly, the most potent inhibitors found are those that possess a trimethylammonium group but have chemically blocked the zinc coordinating functionalities. The results obtained suggest that PC-PLC(Bc) inhibition is not due to the interaction of compounds with the phospholipase catalytic zinc atoms, but rather results from the inhibitor cationic group recognition by the PC-PLC(Bc) amino acids involved in choline lipid binding.

  16. The direct interaction of phospholipase C-gamma 1 with phospholipase D2 is important for epidermal growth factor signaling.

    PubMed

    Jang, Il Ho; Lee, Sukmook; Park, Jong Bae; Kim, Jong Hyun; Lee, Chang Sup; Hur, Eun-Mi; Kim, Il Shin; Kim, Kyong-Tai; Yagisawa, Hitoshi; Suh, Pann-Ghill; Ryu, Sung Ho

    2003-05-16

    The epidermal growth factor (EGF) receptor has an important role in cellular proliferation, and the enzymatic activity of phospholipase C (PLC)-gamma1 is regarded to be critical for EGF-induced mitogenesis. In this study, we report for the first time a phospholipase complex composed of PLC-gamma1 and phospholipase D2 (PLD2). PLC-gamma1 is co-immunoprecipitated with PLD2 in COS-7 cells. The results of in vitro binding analysis and co-immunoprecipitation analysis in COS-7 cells show that the Src homology (SH) 3 domain of PLC-gamma1 binds to the proline-rich motif within the Phox homology (PX) domain of PLD2. The interaction between PLC-gamma1 and PLD2 is EGF stimulation-dependent and potentiates EGF-induced inositol 1,4,5-trisphosphate (IP(3)) formation and Ca(2+) increase. Mutating Pro-145 and Pro-148 within the PX domain of PLD2 to leucines disrupts the interaction between PLC-gamma1 and PLD2 and fails to potentiate EGF-induced IP(3) formation and Ca(2+) increase. However, neither PLD2 wild type nor PLD2 mutant affects the EGF-induced tyrosine phosphorylation of PLC-gamma1. These findings suggest that, upon EGF stimulation, PLC-gamma1 directly interacts with PLD2 and this interaction is important for PLC-gamma1 activity.

  17. Bee Venom Phospholipase A2: Yesterday’s Enemy Becomes Today’s Friend

    PubMed Central

    Lee, Gihyun; Bae, Hyunsu

    2016-01-01

    Bee venom therapy has been used to treat immune-related diseases such as arthritis for a long time. Recently, it has revealed that group III secretory phospholipase A2 from bee venom (bee venom group III sPLA2) has in vitro and in vivo immunomodulatory effects. A growing number of reports have demonstrated the therapeutic effects of bee venom group III sPLA2. Notably, new experimental data have shown protective immune responses of bee venom group III sPLA2 against a wide range of diseases including asthma, Parkinson’s disease, and drug-induced organ inflammation. It is critical to evaluate the beneficial and adverse effects of bee venom group III sPLA2 because this enzyme is known to be the major allergen of bee venom that can cause anaphylactic shock. For many decades, efforts have been made to avoid its adverse effects. At high concentrations, exposure to bee venom group III sPLA2 can result in damage to cellular membranes and necrotic cell death. In this review, we summarized the current knowledge about the therapeutic effects of bee venom group III sPLA2 on several immunological diseases and described the detailed mechanisms of bee venom group III sPLA2 in regulating various immune responses and physiopathological changes. PMID:26907347

  18. Structure and function of lysosomal phospholipase A2 and lecithin:cholesterol acyltransferase

    NASA Astrophysics Data System (ADS)

    Glukhova, Alisa; Hinkovska-Galcheva, Vania; Kelly, Robert; Abe, Akira; Shayman, James A.; Tesmer, John J. G.

    2015-03-01

    Lysosomal phospholipase A2 (LPLA2) and lecithin:cholesterol acyltransferase (LCAT) belong to a structurally uncharacterized family of key lipid-metabolizing enzymes responsible for lung surfactant catabolism and for reverse cholesterol transport, respectively. Whereas LPLA2 is predicted to underlie the development of drug-induced phospholipidosis, somatic mutations in LCAT cause fish eye disease and familial LCAT deficiency. Here we describe several high-resolution crystal structures of human LPLA2 and a low-resolution structure of LCAT that confirms its close structural relationship to LPLA2. Insertions in the α/β hydrolase core of LPLA2 form domains that are responsible for membrane interaction and binding the acyl chains and head groups of phospholipid substrates. The LCAT structure suggests the molecular basis underlying human disease for most of the known LCAT missense mutations, and paves the way for rational development of new therapeutics to treat LCAT deficiency, atherosclerosis and acute coronary syndrome.

  19. Phospholipase D toxins of brown spider venom convert lysophosphatidylcholine and sphingomyelin to cyclic phosphates.

    PubMed

    Lajoie, Daniel M; Zobel-Thropp, Pamela A; Kumirov, Vlad K; Bandarian, Vahe; Binford, Greta J; Cordes, Matthew H J

    2013-01-01

    Venoms of brown spiders in the genus Loxosceles contain phospholipase D enzyme toxins that can cause severe dermonecrosis and even death in humans. These toxins cleave the substrates sphingomyelin and lysophosphatidylcholine in mammalian tissues, releasing the choline head group. The other products of substrate cleavage have previously been reported to be monoester phospholipids, which would result from substrate hydrolysis. Using (31)P NMR and mass spectrometry we demonstrate that recombinant toxins, as well as whole venoms from diverse Loxosceles species, exclusively catalyze transphosphatidylation rather than hydrolysis, forming cyclic phosphate products from both major substrates. Cyclic phosphates have vastly different biological properties from their monoester counterparts, and they may be relevant to the pathology of brown spider envenomation.

  20. Structure and function of lysosomal phospholipase A2 and lecithin:cholesterol acyltransferase

    PubMed Central

    Glukhova, Alisa; Hinkovska-Galcheva, Vania; Kelly, Robert; Abe, Akira; Shayman, James A; Tesmer, John JG

    2015-01-01

    Lysosomal phospholipase A2 (LPLA2) and lecithin:cholesterol acyltransferase (LCAT) belong to a structurally uncharacterized family of key lipid metabolizing enzymes responsible for lung surfactant catabolism and for reverse cholesterol transport, respectively. Whereas LPLA2 is predicted to underlie the development of drug-induced phospholipidosis, somatic mutations in LCAT cause fish eye disease and familial LCAT deficiency. Here we describe several high resolution crystal structures of human LPLA2 and a low resolution structure of LCAT that confirms its close structural relationship to LPLA2. Insertions in the α/β hydrolase core of LPLA2 form domains that are responsible for membrane interaction and binding the acyl chains and head groups of phospholipid substrates. The LCAT structure suggests the molecular basis underlying human disease for most of the known LCAT missense mutations, and paves the way for rational development of new therapeutics to treat LCAT deficiency, atherosclerosis and acute coronary syndrome. PMID:25727495

  1. Role of cytosolic phospholipase A2 in cytokine-stimulated prostaglandin release by human gallbladder cells.

    PubMed

    Grossmann, E M; Longo, W E; Mazuski, J E; Panesar, N; Kaminski, D L

    2000-01-01

    Eicosanoids are involved in gallbladder inflammation, epithelial water transport, and mucous secretion. Phospholipase Asubscript2 enzymes liberate arachidonic acid from membrane phospholipids for the synthesis of eicosanoids. The purpose of this study was to determine the effect of selective cytoplasmic and secretory phospholipase A2 inhibitors on basal and stimulated arachidonic acid and prostaglandin E2 release in gallbladder cells. Western immunoblotting was employed to evaluate both cytosolic and secretory phospholipase A2 enzymes in human gallbladder cells. Cells were incubated for 22 hours with (3)H-labeled arachidonic acid. Arachidonic acid and prostaglandin E2 release was then measured in the supernate after 2 hours of exposure to human interleukin-1beta, alone or after pretreatment for 1 hour with the inhibitors. Unstimulated gallbladder cells express both 85 kDa cytosolic and 14 kDa secretory phospholipase A2++. The 85 kDa phospholipase A2 was induced by interleukin-1beta, whereas there was no apparent change in secretory phospholipase A2 enzyme concentrations. Both the secretory phospholipase A2 inhibitor p-bromophenylacyl bromide and the cytosolic phospholipase A2 inhibitor arachidonyl trifluoromethyl ketone decreased basal and interleukin-1beta-stimulated arachidonic acid release. In contrast, only inhibition of cytosolic phospholipase A2 led to a decrease in interleukin-1beta-stimulated prostaglandin E2 release. Basal and interleukin-1beta-stimulated arachidonic acid release appears to be the result of the activity of both cytosolic and secretory phospholipase A2. Interleukin-1beta-stimulated prostaglandin E2 release appears to be dependent on the activity of cytosolic phospholipase A2.

  2. IV treatment at home

    MedlinePlus

    ... venous catheter - home; Port - home; PICC line - home; Infusion therapy - home; Home health care - IV treatment ... is given quickly, all at once. A slow infusion, which means the medicine is given slowly over ...

  3. GCF Mark IV development

    NASA Technical Reports Server (NTRS)

    Mortensen, L. O.

    1982-01-01

    The Mark IV ground communication facility (GCF) as it is implemented to support the network consolidation program is reviewed. Changes in the GCF are made in the area of increased capacity. Common carrier circuits are the medium for data transfer. The message multiplexing in the Mark IV era differs from the Mark III era, in that all multiplexing is done in a GCF computer under GCF software control, which is similar to the multiplexing currently done in the high speed data subsystem.

  4. Crystallization and preliminary X-ray analysis of cardiotoxic phospholipase A2 from Ophiophagus hannah (king cobra).

    PubMed

    Wang, Z; Zhuang, M; Shu, Y; Zhang, H; Song, S; Lin, Z

    2001-05-01

    An acidic phospholipase A2 exhibiting cardiotoxicity, myotoxicity and anti-platelet activity was isolated from Ophiophagus hannah (king cobra) from Guangxi, China. It contains an unusual 'pancreatic loop'. The enzyme was purified to homogeneity and crystallized using polyethylene glycol and ethylene glycol as precipitants. The crystal belongs to space group C2, with unit-cell parameters a = 117.92, b = 62.94, c = 57.16 A, beta = 100.93 degrees. Diffraction data were collected to 2.6 A.

  5. Inhibition of purified lysosomal phospholipase A1 by beta-adrenoceptor blockers.

    PubMed

    Pappu, A S; Yazaki, P J; Hostetler, K Y

    1985-02-15

    Inhibition of rat liver lysosomal phospholipases is one of the main events that leads to accumulation of tissue phospholipids during drug-induced phospholipidosis. Drug inhibition of lysosomal phospholipase A may occur by direct effects of drugs on the enzyme (or substrate) or by drug-induced increases in intralysosomal pH. Although beta-adrenoceptor blockers have not been reported to cause lipid storage, they do inhibit lysosomal phospholipase A. To investigate the structural requirements for drug inhibition, we studied the effects of six beta-adrenoceptor blockers on purified rat liver lysosomal phospholipase A1. The agents studied include: propranolol, timolol, metoprolol, practolol, atenolol and the combined alpha and beta adrenoceptor blocking agent, labetalol. The drugs varied by two logs in their abilities to inhibit phospholipase A1 activity. The relative inhibitory potencies were propranolol greater than labetalol much greater than timolol greater than metoprolol much greater than practolol greater than atenolol. Our studies identify drug hydrophobicity as a key determinant for phospholipase A1 inhibition. A strong negative correlation was noted between the octanol/water partition coefficients and IC50 for phospholipase inhibition (r = -0.91). The ability of propranolol to inhibit phospholipase A1 was identical for the d, l and the d and l stereoisomers.

  6. Superiority of second over first generation chemotherapy in a randomized trial for stage III-IV intermediate and high-grade non-Hodgkin's lymphoma (NHL): the 1980-1985 EORTC trial. The EORTC Lymphoma Group.

    PubMed

    Carde, P; Meerwaldt, J H; van Glabbeke, M; Somers, R; Monconduit, M; Thomas, J; de Wolf-Peeters, C; de Pauw, B; Tanguy, A; Kluin-Nelemans, J C

    1991-06-01

    A first-generation CHOP-like cyclic combination chemotherapy (CT) regimen using cyclophosphamide 600 mg/m2 IV d1, hydroxorubicin (doxorubicin) 50 mg/m2 IV d1, VM26 60 mg/m2 IV d1, and prednisone 40 mg/m2 PO d1-5 (CHVmP) was compared to a second-generation combination wherein vincristine 1.4 mg/m2 IV and bleomycin 6 mg/m2 IM/IV were added at mid-interval (d15) to the former drugs (CHVmP + VB) in the treatment of intermediate- and high-grade malignant NHL. From April 1980 to January 1986, 141 eligible patients with stage III-IV unfavorable histologies (except T lymphoblastic NHL) entered this EORTC randomized trial. In both arms adjuvant radiotherapy (30 Gy) was given in instances of bulky or residual disease. In all patient subsets the outcome favored the second-generation regimen. The difference was even greater in patients with Diffuse Large Cell Lymphoma (DLCL). At 5 years, overall survival was 53% with CHVmP + VB versus 29% (p = 0.002). The advantage was due to a higher complete remission (CR) rate (80% versus 50%, p = 0.01). Indeed, once CR was achieved the relapse-free survival (RFS) was not significantly influenced (59% versus 49%). No significant additional toxicity could be attributed to vincristine and bleomycin. This study demonstrates a clear benefit for intermediate- and high-risk malignant NHL and particularly DLCL from intercalating non-myelotoxic drugs at mid-cycle intervals, without adverse effects.

  7. Histochemical demonstration of phospholipase B (lysolecithinase) activity in rat tissues.

    PubMed

    Ottolenghi, A; Pickett, J P; Greene, W B

    1966-12-01

    A method has been developed for the histochemical demonstration of phospholipase B (lysolecithinase) of rat tissues. The enzyme attacks lysolecithin with liberation of 1 mole of glycerylphosphorylcholine and 1 mole of fatty acid. The recommended procedure involves use of 6-10 micro frozen sections, fixed in cold calcium-formol and incubated at 37 degrees C in Tris buffered medium at pH 6.6 containing 2.2 X 10(-3) M lysolecithin and 1% cobalt acetate. The fatty acid liberated by enzymatic hydrolysis is trapped as a cobalt precipitate and is then converted to a black-brown precipitate by treatment with dilute ammonium sulfide in cold isotonic saline. Equivalent amounts of fatty acid and glycerylphosphorylcholine are recovered by extraction and analysis of the incubated sections and of the incubation medium, thus proving that lysolecithin hydrolysis occurs under the proposed reaction conditions. Staining is reduced by treating the sections with copper ions, mercury compounds, alcohols, acetone and by heating at 60 degrees C prior to incubation with substrate. Lowering of the pH of the incubation medium has similar effect. These findings are interpreted as evidence of the enzymatic nature of the reaction. Cells exhibiting a positive staining are found in the lamina propria of the intestinal villi and crypts, in the red pulp of the spleen and in the interstitial tissue of lung, liver and thymus. Similar elements are present in bone marrow smears and in leukocyte preparations obtained by peritoneal lavage. The morphologic and staining characteristics of these cells correspond to those of the eosinophilic leukocytes. Physical and chemical agents (x-irradiation, corticosteroids) which sharply decrease the number of eosinophils also reduce the number of cells shown histochemically to hydrolyze lysolecithin. A correspondent diminution of phospholipase B activity of homogenates of the same tissues can be shown in vitro. Differences in tissue distribution and chemical

  8. Synthesis of mixed-chain phosphatidylcholines including coumarin fluorophores for FRET-based kinetic studies of phospholipase A(2) enzymes.

    PubMed

    Wang, Manlin; Pinnamaraju, Susmitha; Ranganathan, Radha; Hajdu, Joseph

    2013-01-01

    Phospholipase A2 (PLA2) enzymes catalyze the hydrolysis of the sn-2 ester linkage of glycerophospholipids to produce fatty acids and lysophospholipids. A significant number of mammalian phospholipases comprise a family of secreted PLA2 enzymes, found in specific tissues and cellular locations, exhibiting unique enzymatic properties and distinct biological functions. Development of new real-time spectrofluorimetric PLA2 assays should facilitate the kinetic characterization and mechanistic elucidation of the isozymes in vitro, with the potential applicability to detect and measure catalytic PLA2 activity in tissues and cellular locations. Here we report a new synthesis of double-labeled phosphatidylcholine analogs with chain-terminal reporter groups including coumarin fluorophores for fluorescence resonance energy transfer (FRET)-based kinetic studies of PLA2 enzymes. The use of coumarin derivatives as fluorescent labels provides reporter groups with substantially decreased size compared to the first generation of donor-acceptor pairs of fluorescent phospholipids. The key advantage of the design is to interfere less with the physicochemical properties of the acyl chains, thereby improving the substrate quality of the synthetic probes. In order to assess the impact of the fluorophore substituents on the catalytic hydrolysis and on the phospholipid packing in the lipid-water interface of the assay, we used the experimentally determined specific activity of bee-venom phospholipase A2 as a model for the secretory PLA2 enzymes. Specifically, the rate of PLA2 hydrolysis of the coumarin labeled phosphatidylcholine analogs was less than three times slower than the natural substrate dipalmitoyl phosphatidylcholine (DPPC) under the same experimental conditions. Furthermore, variation of the mole fraction of the synthetic phosphatidylcholine vs. that of the natural DPPC substrate showed nearly ideal mixing behavior in the phospholipid-surfactant aggregates of the assay. The

  9. Messenger molecules of the phospholipase signaling system have dual effects on vascular smooth muscle contraction.

    PubMed

    Vidulescu, Cristina; Mironneau, J.; Mironneau, Chantal; Popescu, L. M.

    2000-01-01

    Background and methods. In order to investigate the role of phospholipases and their immediately derived messengers in agonist-induced contraction of portal vein smooth muscle, we used the addition in the organ bath of exogenous molecules such as: phospholipases C, A(2), and D, diacylglycerol, arachidonic acid, phosphatidic acid, choline. We also used substances modulating activity of downstream molecules like protein kinase C, phosphatidic acid phosphohydrolase, or cyclooxygenase. Results. a) Exogenous phospholipases C or A(2), respectively, induced small agonist-like contractions, while exogenous phospholipase D did not. Moreover, phospholipase D inhibited spontaneous contractions. However, when added during noradrenaline-induced plateau, phospholipase D shortly potentiated it. b) The protein kinase C activator, phorbol dibutyrate potentiated both the exogenous phospholipase C-induced contraction and the noradrenaline-induced plateau, while the protein kinase C inhibitor 1-(-5-isoquinolinesulfonyl)-2-methyl-piperazine relaxed the plateau. c) When added before noradrenaline, indomethacin inhibited both phasic and tonic contractions, but when added during the tonic contraction shortly potentiated it. Arachidonic acid strongly potentiated both spontaneous and noradrenaline-induced contractions, irrespective of the moment of its addition. d) In contrast, phosphatidic acid inhibited spontaneous contractile activity, nevertheless it was occasionally capable of inducing small contractions, and when repetitively added during the agonist-induced tonic contraction, produced short potentiations of the plateau. Pretreatment with propranolol inhibited noradrenaline-induced contractions and further addition of phosphatidic acid augmented this inhibition. Choline augmented the duration and amplitude of noradrenaline-induced tonic contraction and final contractile oscillations. Conclusions. These data suggest that messengers produced by phospholipase C and phospholipase A(2

  10. Purification and characterization of a membrane-associated phospholipase A2 from rat spleen. Its comparison with a cytosolic phospholipase A2 S-1.

    PubMed

    Ono, T; Tojo, H; Kuramitsu, S; Kagamiyama, H; Okamoto, M

    1988-04-25

    A membrane-associated phospholipase A2 was purified from rat spleen. The phospholipase A2 was solubilized from the 108,000 x g pellet fraction with 0.3% lithium dodecyl sulfate and then purified to homogeneity by successive DEAE-Cellulofine AM, octyl-Sepharose, Cellulofine GCL 300-m, S-Sepharose, and Bio-Gel P-30 chromatographies in the presence of 0.5% 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonate. The apparent Mr of the enzyme, estimated on sodium dodecyl sulfate polyacrylamide gel electrophoresis, was about 13,600. The purified enzyme had a pH optimum in the range of pH 8.0-9.5 and required the presence of Ca2+ (4 mM) for its maximal activity. The enzyme preferentially hydrolyzed the 2-acyl ester bonds of phosphatidylglycerol in the presence and absence of sodium cholate or sodium deoxycholate. Unlike the phospholipase A2 of rat spleen supernatant, no immunocross-reactivity was observed between the purified enzyme and anti-rat pancreatic phospholipase A2 antibody. The N-terminal amino acid sequence of the enzyme was determined and found to be homologous to that of viperid and crotalid venom phospholipases A2. The results in this and the preceding report (Tojo, H., Ono, T., Kuramitsu, S., Kagamiyama, H., and Okamoto, M. (1988) J. Biol. Chem. 263, 5724-5731) demonstrate that rat spleen contains two genetically distinct phospholipase A2 isoenzymes.

  11. Therapeutic application of natural inhibitors against snake venom phospholipase A2

    PubMed Central

    Perumal Samy, Ramar; Gopalakrishnakone, Ponnampalam; Chow, Vincent TK

    2012-01-01

    Natural inhibitors occupy an important place in the potential to neutralize the toxic effects caused by snake venom proteins and enzymes. It has been well recognized for several years that animal sera, some of the plant and marine extracts are the most potent in neutralizing snake venom phospholipase A2 (svPLA2). The implication of this review to update the latest research work which has been accomplished with svPLA2 inhibitors from various natural sources like animal, marine organisms presents a compilation of research in this field over the past decade and revisiting the previous research report including those found in plants. In addition to that the bioactive compounds/inhibitor molecules from diverse sources like aristolochic alkaloid, flavonoids and neoflavonoids from plants, hydrocarbones ­2, 4 dimethyl hexane, 2 methylnonane, and 2, 6 dimethyl heptane obtained from traditional medicinal plants Tragia involucrata (Euphorbiaceae) member of natural products involved for the inhibitory potential of phospholipase A2 (PLA2) enzymes in vitro and also decrease both oedema induced by snake venom as well as human synovial fluid PLA2. Besides marine natural products that inhibit PLA2 are manoalide and its derivatives such as scalaradial and related compounds, pseudopterosins and vidalols, tetracylne from synthetic chemicals etc. There is an overview of the role of PLA2 in inflammation that provides a rationale for seeking inhibitors of PLA2 as anti-inflammatory agents. However, more studies should be considered to evaluate antivenom efficiency of sera and other agents against a variety of snake venoms found in various parts of the world. The implications of these new groups of svPLA2 toxin inhibitors in the context of our current understanding of snake biology as well as in the development of new novel antivenoms therapeutics agents in the efficient treatment of snake envenomations are discussed. PMID:22359435

  12. Identification of a secretory phospholipase A2 from Papaver somniferum L. that transforms membrane phospholipids.

    PubMed

    Jablonická, Veronika; Mansfeld, Johanna; Heilmann, Ingo; Obložinský, Marek; Heilmann, Mareike

    2016-09-01

    The full-length sequence of a new secretory phospholipase A2 was identified in opium poppy seedlings (Papaver somniferum L.). The cDNA of poppy phospholipase A2, denoted as pspla2, encodes a protein of 159 amino acids with a 31 amino acid long signal peptide at the N-terminus. PsPLA2 contains a PLA2 signature domain (PA2c), including the Ca(2+)-binding loop (YGKYCGxxxxGC) and the catalytic site motif (DACCxxHDxC) with the conserved catalytic histidine and the calcium-coordinating aspartate residues. The aspartate of the His/Asp dyad playing an important role in animal sPLA2 catalysis is substituted by a serine residue. Furthermore, the PsPLA2 sequence contains 12 conserved cysteine residues to form 6 structural disulfide bonds. The calculated molecular weight of the mature PsPLA2 is 14.0 kDa. Based on the primary structure PsPLA2 belongs to the XIB group of PLA2s. Untagged recombinant PsPLA2 obtained by expression in Escherichia coli, renaturation from inclusion bodies and purification by cation-exchange chromatography was characterized in vitro. The pH optimum for activity of PsPLA2 was found to be pH 7, when using mixed micelles of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and Triton X-100. PsPLA2 specifically cleaves fatty acids from the sn-2 position of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and shows a pronounced preference for PC over phosphatidyl ethanolamine, -glycerol and -inositol. The active recombinant enzyme was tested in vitro against natural phospholipids isolated from poppy plants and preferably released the unsaturated fatty acids, linoleic acid and linolenic acid, from the naturally occurring mixture of substrate lipids.

  13. Interplanetary Type IV Bursts

    NASA Astrophysics Data System (ADS)

    Hillaris, A.; Bouratzis, C.; Nindos, A.

    2016-08-01

    We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (interplanetary type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 interplanetary type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on average 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal

  14. Cytosolic Phospholipase A2 and Lysophospholipids in Tumor Angiogenesis

    PubMed Central

    Linkous, Amanda G.

    2010-01-01

    Background Lung cancer and glioblastoma multiforme are highly angiogenic and, despite advances in treatment, remain resistant to therapy. Cytosolic phospholipase A2 (cPLA2) activation contributes to treatment resistance through transduction of prosurvival signals. We investigated cPLA2 as a novel molecular target for antiangiogenesis therapy. Methods Glioblastoma (GL261) and Lewis lung carcinoma (LLC) heterotopic tumor models were used to study the effects of cPLA2 expression on tumor growth and vascularity in C57/BL6 mice wild type for (cPLA2α+/+) or deficient in (cPLA2α−/−) cPLA2α, the predominant isoform in endothelium (n = 6–7 mice per group). The effect of inhibiting cPLA2 activity on GL261 and LLC tumor growth was studied in mice treated with the chemical cPLA2 inhibitor 4-[2-[5-chloro-1-(diphenylmethyl)-2-methyl-1H-indol-3-yl]-ethoxy]benzoic acid (CDIBA). Endothelial cell proliferation and function were evaluated by Ki-67 immunofluorescence and migration assays in primary cultures of murine pulmonary microvascular endothelial cells (MPMEC) isolated from cPLA2α+/+ and cPLA2α−/− mice. Proliferation, invasive migration, and tubule formation were assayed in mouse vascular endothelial 3B-11 cells treated with CDIBA. Effects of lysophosphatidylcholine, arachidonic acid, and lysophosphatidic acid (lipid mediators of tumorigenesis and angiogenesis) on proliferation and migration were examined in 3B-11 cells and cPLA2α−/− MPMEC. All statistical tests were two-sided. Results GL261 tumor progression proceeded normally in cPLA2α+/+ mice, whereas no GL261 tumors formed in cPLA2α−/− mice. In the LLC tumor model, spontaneous tumor regression was observed in 50% of cPLA2α−/− mice. Immunohistochemical examination of the remaining tumors from cPLA2α−/− mice revealed attenuated vascularity (P ≤ .001) compared with tumors from cPLA2α+/+ mice. Inhibition of cPLA2 activity by CDIBA resulted in a delay in tumor growth (eg, LLC model: average

  15. Design of specific peptide inhibitors of phospholipase A2: structure of a complex formed between Russell's viper phospholipase A2 and a designed peptide Leu-Ala-Ile-Tyr-Ser (LAIYS).

    PubMed

    Chandra, Vikas; Jasti, Jayasankar; Kaur, Punit; Dey, Sharmistha; Srinivasan, A; Betzel, Ch; Singh, T P

    2002-10-01

    Phospholipase A(2) (EC 3.1.1.4) is a key enzyme of the cascade mechanism involved in the production of proinflammatory compounds known as eicosanoids. The binding of phospholipase A(2) to membrane surfaces and the hydrolysis of phospholipids are thought to involve the formation of a hydrophobic channel into which a single substrate molecule diffuses before cleavage. In order to regulate the production of proinflammatory compounds, a specific peptide inhibitor of PLA(2), Leu-Ala-Ile-Tyr-Ser, has been designed. Phospholipase A(2) from Daboia russelli pulchella (DPLA(2)) and peptide Leu-Ala-Ile-Tyr-Ser (LAIYS) have been co-crystallized. The structure of the complex has been determined and refined to 2.0 A resolution. The structure contains two crystallographically independent molecules of DPLA(2), with one molecule of peptide specifically bound to one of them. The overall conformations of the two molecules are essentially similar except in three regions; namely, the calcium-binding loop including Trp31 (residues 25-34), the beta-wing consisting of two antiparallel beta-strands (residues 74-85) and the C-terminal region (residues 119-133). Of these, the most striking difference pertains to the orientation of Trp31 in the two molecules. The conformation of Trp31 in molecule A was suitable to allow the binding of peptide LAIYS, while that in molecule B prevented the entry of the ligand into the hydrophobic channel. The structure of the complex clearly showed that the OH group of Tyr of the inhibitor formed hydrogen bonds with both His48 N(delta1) and Asp49 O(delta1), while O(gamma)H of Ser was involved in a hydrogen bond with Trp31. Other peptide backbone atoms interact with protein through water molecules, while Leu, Ala and Ile form strong hydrophobic interactions with the residues of the hydrophobic channel.

  16. Coordination of tetravalent actinides (An = Th(IV), U(IV), Np(IV), Pu(IV)) with DOTA - from dimers to hexamers.

    PubMed

    Tamain, Christelle; Dumas, Thomas; Hennig, Christoph; Guilbaud, Philippe

    2017-03-10

    Three tetravalent actinide (An(IV)) hexanuclear clusters with the octahedral core [An6(OH)4O4]12+ (An(IV) = U(IV), Np(IV), Pu(IV)) were structurally characterized in solid state and in aqueous solution using single crystal X-ray diffraction, X-ray absorption, IR, Raman and UV-Visible spectroscopy. The observed structure, [An6(OH)4O4(H2O)8(HDOTA)4].HCl/HNO3.nH2O (An = U (I), Np (II), Pu (III)), consists of a An(IV) hexanuclear pseudo-octahedral cluster stabilized by DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) ligands. The six actinide atoms are connected through alternative µ3-O2- and µ3-OH- groups. EXAFS investigations combined with UV-vis spectroscopy evidence the same local structure in moderate acidic and neutral aqueous solutions. The synthesis mechanism was partially elucidated and the main physicochemical properties (pH range stability, solubility and protonation constant) of the cluster were determined. The results underline the importance (i) to consider such polynuclear species in thermodynamic models and (ii) of competing reactions between hydrolysis and complexation. It is interesting to note that the same synthesis route with thorium(IV) leads to the formation of a dimer, Th2(H2O)10(H2DOTA)2.4NO3.xH2O (IV), which contrasts to the structure of the other An(IV) hexamers.

  17. Ostrich pancreatic phospholipase A(2): purification and biochemical characterization.

    PubMed

    Ben Bacha, Abir; Gargouri, Youssef; Bezzine, Sofiane; Mosbah, Habib; Mejdoub, Hafedh

    2007-09-15

    Ostrich pancreatic phospholipase A(2) (OPLA(2)) was purified from delipidated pancreases. Pure protein was obtained after heat treatment (70 degrees C), precipitation by ammonium sulphate and ethanol, respectively followed by sequential column chromatography on MonoQ Sepharose and size exclusion HPLC column. Purified OPLA(2), which is not a glycosylated protein, was found to be monomeric protein with a molecular mass of 13773.93 Da. A specific activity of 840U/mg for purified OPLA(2) was measured at optimal conditions (pH 8.2 and 37 degrees C) in the presence of 4 mM NaTDC and 10 mM CaCl(2) using PC as substrate. This enzyme was also found to be able to hydrolyze, at low surface pressure, 1,2-dilauroyl-sn-glycero-3 phosphocholine (di C(12)-PC) monolayers. Maximal activity was measured at 5-8 mNm(-1). The sequence of the first 22 amino-acid residues at the N-terminal extremity of purified bird PLA(2) was determined by automatic Edman degradation and showed a high sequence homology with known mammal pancreatic secreted phospholipases A(2).

  18. Molecular Characterization of Three Novel Phospholipase A2 Proteins from the Venom of Atheris chlorechis, Atheris nitschei and Atheris squamigera

    PubMed Central

    Wang, He; Chen, Xiaole; Zhou, Mei; Wang, Lei; Chen, Tianbao; Shaw, Chris

    2016-01-01

    Secretory phospholipase A2 (sPLA2) is known as a major component of snake venoms and displays higher-order catalytic hydrolysis functions as well as a wide range of pathological effects. Atheris is not a notoriously dangerous genus of snakes although there are some reports of fatal cases after envenomation due to the effects of coagulation disturbances and hemorrhaging. Molecular characterization of Atheris venom enzymes is incomplete and there are only a few reports in the literature. Here, we report, for the first time, the cloning and characterization of three novel cDNAs encoding phospholipase A2 precursors (one each) from the venoms of the Western bush viper (Atheris chlorechis), the Great Lakes bush viper (Atheris nitschei) and the Variable bush viper (Atheris squamigera), using a “shotgun cloning” strategy. Open-reading frames of respective cloned cDNAs contained putative 16 residue signal peptides and mature proteins composed of 121 to 123 amino acid residues. Alignment of mature protein sequences revealed high degrees of structural conservation and identity with Group II venom PLA2 proteins from other taxa within the Viperidae. Reverse-phase High Performance Liquid Chromatography (HPLC) profiles of these three snake venoms were obtained separately and chromatographic fractions were assessed for phospholipase activity using an egg yolk suspension assay. The molecular masses of mature proteins were all identified as approximately 14 kDa. Mass spectrometric analyses of the fractionated oligopeptides arising from tryptic digestion of intact venom proteins, was performed for further structural characterization. PMID:27258312

  19. Disintegration of lysosomes mediated by GTPgammaS-treated cytosol: possible involvement of phospholipases.

    PubMed

    Sai, Y; Matsuda, T; Arai, K; Ohkuma, S

    1998-04-01

    We showed previously that cytosol treated with guanosine 5'-O-(3-thiotriphosphate) (GTP-gammaS) disintegrated lysosomes in vitro [Sai, Y. et al. (1994) Biochem. Biophys. Res. Commun. 198, 869-877] in time-, temperature-, and dose-dependent manners. This also requires ATP, however, the latter can be substituted with deoxy-ATP, ADP, or ATPgammaS, suggesting no requirement of ATP hydrolysis. The lysis was inhibited by several chemical modifiers, including N-ethylmaleimide, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, and by various phospholipase inhibitors (trifluoperazine, p-bromophenacyl bromide, nordihydroguaiaretic acid, W-7, primaquine, compound 48/80, neomycin, and gentamicin), but not by ONO-RS-082, an inhibitor of phospholipase A2. The reaction was also inhibited by phospholipids (phosphatidylinositol, phosphatidylserine, phosphatidic acid, and phosphatidylcholine) and diacylglycerol. Among the phospholipase A2 hydrolysis products of phospholipids, unsaturated fatty acids (oleate, linoleate, and arachidonate) and lysophospholipid (lysophosphatidylcholine) by themselves broke lysosomes down directly, whereas saturated fatty acids (palmitate and stearate) had little effect. We found that GTPgammaS-stimulated cytosolic phospholipase A2 activity was highly sensitive to ONO-RS-082. These results suggest the participation of phospholipase(s), though not cytosolic phospholipase A2, in the GTPgammaS-dependent lysis of lysosomes.

  20. Histamine H1 and endothelin ETB receptors mediate phospholipase D stimulation in rat brain hippocampal slices.

    PubMed

    Sarri, E; Picatoste, F; Claro, E

    1995-08-01

    Different neurotransmitter receptor agonists [carbachol, serotonin, noradrenaline, histamine, endothelin-1, and trans-(1S,3R)-aminocyclopentyl-1,3-dicarboxylic acid (trans-ACPD)], known as stimuli of phospholipase C in brain tissue, were tested for phospholipase D stimulation in [32P]Pi-prelabeled rat brain cortical and hippocampal slices. The accumulation of [32P]phosphatidylethanol was measured as an index of phospholipase D-catalyzed transphosphatidylation in the presence of ethanol. Among the six neurotransmitter receptor agonists tested, only noradrenaline, histamine, endothelin-1, and trans-ACPD stimulated phospholipase D in hippocampus and cortex, an effect that was strictly dependent of the presence of millimolar extracellular calcium concentrations. The effect of histamine (EC50 18 microM) was inhibited by the H1 receptor antagonist mepyramine with a Ki constant of 0.7 nM and was resistant to H2 and H3 receptor antagonists (ranitidine and tioperamide, respectively). Endothelin-1-stimulated phospholipase D (EC50 44 nM) was not blocked by BQ-123, a specific antagonist of the ETA receptor. Endothelin-3 and the specific ETB receptor agonist safarotoxin 6c were also able to stimulate phospholipase D with efficacies similar to that of endothelin-1, and EC50 values of 16 and 3 nM, respectively. These results show that histamine and endothelin-1 stimulate phospholipase D in rat brain through H1 and ETB receptors, respectively.

  1. Modulation of radiation induced lipid peroxidation by phospholipase A 2 and calmodulin antagonists: Relevance to detoxification

    NASA Astrophysics Data System (ADS)

    Varshney, Rajeev; Kale, R. K.

    1995-04-01

    Ghost membranes prepared from erythrocytes of Swiss albino mice were irradiated with 0.9 Gy s -1. Lipid peroxidation initiated by ionizing radiation was enhanced by phospholipase A 2, and required both phospholipase A 2 and GSH-peroxidase for consecutive action to convert fatty acid peroxides into corresponding alcohols. The ability of phospholipase A 2 to enhance lipid peroxidation was increased in presence of Ca 2+. However, in combination, phospholipase A 2 and GSH-peroxidase were effective in inhibiting lipid peroxidation. These findings show that free fatty acid peroxides considerably increase the peroxidation. Calmodulin antagonists inhibit lipid peroxidation and decrease the radiation induced release of Ca 2+ from the membranes. Our results suggest the importance of Ca 2+ dependent phospholipase A 2 in detoxification of fatty acid peroxides in the membranes. It is quite possible that scavenging of free radicals by calmodulin antagonists lower the formation of hydroperoxides, resulting in the decrease in activity of phospholipase A 2. Alternatively, decrease in Ca 2+ release due to the calmodulin antagonists might have affected the activity of phospholipase A 2. Our observations might be of considerable significance in the understanding of post irradiation effect on biological membranes.

  2. PLATO IV Accountancy Index.

    ERIC Educational Resources Information Center

    Pondy, Dorothy, Comp.

    The catalog was compiled to assist instructors in planning community college and university curricula using the 48 computer-assisted accountancy lessons available on PLATO IV (Programmed Logic for Automatic Teaching Operation) for first semester accounting courses. It contains information on lesson access, lists of acceptable abbreviations for…

  3. IVS Technology Coordinator Report

    NASA Technical Reports Server (NTRS)

    Whitney, Alan

    2013-01-01

    This report of the Technology Coordinator includes the following: 1) continued work to implement the new VLBI2010 system, 2) the 1st International VLBI Technology Workshop, 3) a VLBI Digital- Backend Intercomparison Workshop, 4) DiFX software correlator development for geodetic VLBI, 5) a review of progress towards global VLBI standards, and 6) a welcome to new IVS Technology Coordinator Bill Petrachenko.

  4. The PLATO IV Architecture.

    ERIC Educational Resources Information Center

    Stifle, Jack

    The PLATO IV computer-based instructional system consists of a large scale centrally located CDC 6400 computer and a large number of remote student terminals. This is a brief and general description of the proposed input/output hardware necessary to interface the student terminals with the computer's central processing unit (CPU) using available…

  5. Little Jiffy, Mark IV

    ERIC Educational Resources Information Center

    Kaiser, Henry F.; Rice, John

    1974-01-01

    In this paper three changes and one new development for the method of exploratory factor analysis (a second generation Little Jiffy) developed by Kaiser are described. Following this short description a step-by-step computer algorithm of the revised method, dubbed Little Jiffy, Mark IV is presented. (MP)

  6. A rapid phospholipase A2 bioassay using 14C-oleate-labelled E. coli bacterias.

    PubMed

    Meyer, T; von Wichert, P; Weins, D

    1989-02-01

    Two methods of phospholipase A2 determination using 14C-labelled E. coli bacterias as substrate were compared. One method works with a filter membrane for separation of cleaved 14C-oleate from remaining phospholipids, the other uses the well-known thin-layer chromatography for lipid analysis. Some features of human serum phospholipase A2 regarding pH and Ca2+ dependency were investigated. Possible sources of errors were discussed. It was shown that either method can differentiate between normal and pathologically elevated phospholipase A2 levels, but that the filter method is superior in terms of sensitivity and workload.

  7. Natural phospholipase A(2) myotoxin inhibitor proteins from snakes, mammals and plants.

    PubMed

    Lizano, Sergio; Domont, Gilberto; Perales, Jonas

    2003-12-15

    A renewed interest in the phenomenon of inter- and intra-species resistance towards the toxicity of snake venoms, coupled with the search for new strategies for treatment of snake envenomations, has prompted the discovery of proteins which neutralize the major toxic components of these venoms. Among these emerging groups of proteins are inhibitors of toxic phospholipases A2 (PLA2s), many of which exhibit a wide range of toxic effects including muscle-tissue damage, neurotoxicity, and inflammation. These proteins have been isolated from both venomous and non-venomous snakes, mammals, and most recently from medicinal plant extracts. The snake blood-derived inhibitors have been grouped into three major classes, alpha, beta, and gamma, based on common structural motifs found in other proteins with diverse physiological properties. In mammals, DM64, an anti-myotoxic protein isolated from opossum serum, belongs to the immunoglobulin super gene family and is homologous to human alpha1B-glycoprotein and DM43, a metalloproteinase inhibitor from the same organism. In plants, a short note is made of WSG, a newly described anti-toxic-PLA2 glycoprotein isolated from Withania somnifera (Ashwaganda), a medicinal plant whose aqueous extracts neutralize the PLA2 activity of the Naja naja venom. The implications of these new groups of PLA2 toxin inhibitors in the context of our current understanding of snake biology as well as in the development of novel therapeutic reagents in the treatment of snake envenomations worldwide are discussed.

  8. Secretory phospholipases A2 induce cytokine release from blood and synovial fluid monocytes.

    PubMed

    Triggiani, Massimo; Granata, Francescopaolo; Oriente, Alfonso; Gentile, Marco; Petraroli, Angelica; Balestrieri, Barbara; Marone, Gianni

    2002-01-01

    Secretory phospholipases A2 (sPLA2) are released in the blood of patients with various inflammatory diseases and exert proinflammatory activities by releasing arachidonic acid (AA), the precursor of eicosanoids. We examined the ability of four sPLA2 to activate blood and synovial fluid monocytes in vitro. Monocytes were purified from blood of healthy donors or from synovial fluid of patients with rheumatoid arthritis by negative immunoselection and by adherence to plastic dishes, respectively. The cells were incubated with group IA, IB, IIA and III sPLA2 and the release of TNF-alpha, IL-6 and IL-12 was determined by ELISA. Group IA, IB and IIA sPLA2 induced a concentration-dependent release of TNF-alpha and IL-6 from blood monocytes. These sPLA2 activated IL-12 production only in monocytes preincubated with IFN-gamma. Group IA and IIA sPLA2 also induced TNF-alpha and IL-6 release from synovial fluid monocytes. TNF-alpha and IL-6 release paralleled an increase in their mRNA expression and was independent from the capacity of sPLA2 to mobilize AA. These results indicate that sPLA2 stimulate cytokine release from blood and synovial fluid monocytes by a mechanism at least partially unrelated to their enzymatic activity. This effect may concur with the generation of AA in the proinflammatory activity of sPLA2 released during inflammatory diseases.

  9. Crystal forms of a lysine-49 phospholipase A 2 from the eastern cottonmouth snake

    NASA Astrophysics Data System (ADS)

    Clancy, Laura L.; Rydel, Timothy J.; Muchmore, Steven W.; Holland, Debra R.; Watenpaugh, Keith D.; Finzel, Barry C.; Einspahr, Howard M.

    1990-09-01

    As part of an effort to determine the structure of a lysine-49 variant phospholipase A 2 from the venom of a North American pit viper, the eastern cottonmouth ( Agkistrodon piscivorus piscivorus), we have produced five different crystal forms grown under a variety of crystallization conditions. They include an orthorthombic form (P2 12 12 1 or P2 12 12; a=87.8(3) Å, b=76.2(3) Å, c=57.4(4) Å), an hexagonal form (space group P6 122 or its enantiomer; a= b=62.22(3) Å, c=137.1(3) Å) and two tetragonal forms - a neutral pH form (space group P4 12 12 or its enantiomer; a = b = 81.99(3) Å) and high pH form (space group P4 12 12; a = b = 71.5(1) Å, c = 57.6(2) Å one molecule per asymmetric unit) — the latter of which was used for structure determination.

  10. Legionella pneumophila Effector LpdA Is a Palmitoylated Phospholipase D Virulence Factor.

    PubMed

    Schroeder, Gunnar N; Aurass, Philipp; Oates, Clare V; Tate, Edward W; Hartland, Elizabeth L; Flieger, Antje; Frankel, Gad

    2015-10-01

    Legionella pneumophila is a bacterial pathogen that thrives in alveolar macrophages, causing a severe pneumonia. The virulence of L. pneumophila depends on its Dot/Icm type IV secretion system (T4SS), which delivers more than 300 effector proteins into the host, where they rewire cellular signaling to establish a replication-permissive niche, the Legionella-containing vacuole (LCV). Biogenesis of the LCV requires substantial redirection of vesicle trafficking and remodeling of intracellular membranes. In order to achieve this, several T4SS effectors target regulators of membrane trafficking, while others resemble lipases. Here, we characterized LpdA, a phospholipase D effector, which was previously proposed to modulate the lipid composition of the LCV. We found that ectopically expressed LpdA was targeted to the plasma membrane and Rab4- and Rab14-containing vesicles. Subcellular targeting of LpdA required a C-terminal motif, which is posttranslationally modified by S-palmitoylation. Substrate specificity assays showed that LpdA hydrolyzed phosphatidylinositol, -inositol-3- and -4-phosphate, and phosphatidylglycerol to phosphatidic acid (PA) in vitro. In HeLa cells, LpdA generated PA at vesicles and the plasma membrane. Imaging of different phosphatidylinositol phosphate (PIP) and organelle markers revealed that while LpdA did not impact on membrane association of various PIP probes, it triggered fragmentation of the Golgi apparatus. Importantly, although LpdA is translocated inefficiently into cultured cells, an L. pneumophila ΔlpdA mutant displayed reduced replication in murine lungs, suggesting that it is a virulence factor contributing to L. pneumophila infection in vivo.

  11. Disposition and metabolism of darapladib, a lipoprotein-associated phospholipase A2 inhibitor, in humans.

    PubMed

    Dave, Mehul; Nash, Mike; Young, Graeme C; Ellens, Harma; Magee, Mindy H; Roberts, Andrew D; Taylor, Maxine A; Greenhill, Robert W; Boyle, Gary W

    2014-03-01

    The absorption, metabolism, and excretion of darapladib, a novel inhibitor of lipoprotein-associated phospholipase A2, was investigated in healthy male subjects using [(14)C]-radiolabeled material in a bespoke study design. Disposition of darapladib was compared following single i.v. and both single and repeated oral administrations. The anticipated presence of low circulating concentrations of drug-related material required the use of accelerator mass spectrometry as a sensitive radiodetector. Blood, urine, and feces were collected up to 21 days post radioactive dose, and analyzed for drug-related material. The principal circulating drug-related component was unchanged darapladib. No notable metabolites were observed in plasma post-i.v. dosing; however, metabolites resulting from hydroxylation (M3) and N-deethylation (M4) were observed (at 4%-6% of plasma radioactivity) following oral dosing, indicative of some first-pass metabolism. In addition, an acid-catalyzed degradant (M10) resulting from presystemic hydrolysis was also detected in plasma at similar levels of ∼5% of radioactivity post oral dosing. Systemic exposure to radioactive material was reduced within the repeat dose regimen, consistent with the notion of time-dependent pharmacokinetics resulting from enhanced clearance or reduced absorption. Elimination of drug-related material occurred predominantly via the feces, with unchanged darapladib representing 43%-53% of the radioactive dose, and metabolites M3 and M4 also notably accounting for ∼9% and 19% of the dose, respectively. The enhanced study design has provided an increased understanding of the absorption, distribution, metabolism and excretion (ADME) properties of darapladib in humans, and substantially influenced future work on the compound.

  12. Inactivation of Phospholipase D Diminishes Acinetobacter baumannii Pathogenesis▿ †

    PubMed Central

    Jacobs, Anna C.; Hood, Indriati; Boyd, Kelli L.; Olson, Patrick D.; Morrison, John M.; Carson, Steven; Sayood, Khalid; Iwen, Peter C.; Skaar, Eric P.; Dunman, Paul M.

    2010-01-01

    Acinetobacter baumannii is an emerging bacterial pathogen of considerable health care concern. Nonetheless, relatively little is known about the organism's virulence factors or their regulatory networks. Septicemia and ventilator-associated pneumonia are two of the more severe forms of A. baumannii disease. To identify virulence factors that may contribute to these disease processes, genetically diverse A. baumannii clinical isolates were evaluated for the ability to proliferate in human serum. A transposon mutant library was created in a strain background that propagated well in serum and screened for members with decreased serum growth. The results revealed that disruption of A. baumannii phospholipase D (PLD) caused a reduction in the organism's ability to thrive in serum, a deficiency in epithelial cell invasion, and diminished pathogenesis in a murine model of pneumonia. Collectively, these results suggest that PLD is an A. baumannii virulence factor. PMID:20194595

  13. Phospholipase C-β1 and schizophrenia-related behaviors.

    PubMed

    Koh, Hae-Young

    2013-09-01

    Abnormal expression patterns of phospholipase C-β1(PLC-β1) in specific brain areas of patients with schizophrenia, and its high genetic linkage to the disorder implicated a pathogenetical involvement of PLC-β1 signaling system. The schizophrenia-related behavioral phenotypes displayed in the mutant mice lacking PLC-β1 (PLC-β1 KO) suggested that PLCβ1-linked signaling pathways may be involved in the neural system whose function is disrupted in the pathogenesis of schizophrenia. In the brain, PLC-β1 is known to be linked to muscarinic acetylcholine receptors, metabotropic glutamatergic, serotonergic, and oxytocinergic systems. The objective of this review is to provide an overview of the current knowledge regarding these schizophrenia-related behaviors and discuss the probable ways in which PLC-β1signalling can be involved in the neural mechanisms for each behavior, which may help suggest future directions for research in this area.

  14. Phospholipase C-γ1 involved in brain disorders.

    PubMed

    Jang, Hyun-Jun; Yang, Yong Ryoul; Kim, Jung Kuk; Choi, Jang Hyun; Seo, Young-Kyo; Lee, Yong Hwa; Lee, Jeung Eun; Ryu, Sung Ho; Suh, Pann-Ghill

    2013-01-01

    Phosphoinositide-specific phospholipase C-γ1 (PLC-γ1) is an important signaling regulator involved in various cellular processes. In brain, PLC-γ1 is highly expressed and participates in neuronal cell functions mediated by neurotrophins. Consistent with essential roles of PLC-γ1, it is involved in development of brain and synaptic transmission. Significantly, abnormal expression and activation of PLC-γ1 appears in various brain disorders such as epilepsy, depression, Huntington's disease and Alzheimer's disease. Thus, PLC-γ1 has been implicated in brain functions as well as related brain disorders. In this review, we discuss the roles of PLC-γ1 in neuronal functions and its pathological relevance to diverse brain diseases.

  15. Defective phosphatidic acid-phospholipase C signaling in diabetic cardiomyopathy.

    PubMed

    Tappia, Paramjit S; Maddaford, Thane G; Hurtado, Cecilia; Dibrov, Elena; Austria, J Alejandro; Sahi, Nidhi; Panagia, Vincenzo; Pierce, Grant N

    2004-03-26

    The effects of exogenous phosphatidic acid (PA) on Ca2+ transients and contractile activity were studied in cardiomyocytes isolated from chronic streptozotocin-induced diabetic rats. In control cells, 25 microM PA induced a significant increase in active cell shortening and Ca2+ transients. PA increased IP3 generation in the control cardiomyocytes and its inotropic effects were blocked by a phospholipase C inhibitor. In cardiomyocytes from diabetic rats, PA induced a 25% decrease in active cell shortening and no significant effect on Ca2+ transients. Basal and PA-induced IP3 generation in diabetic rat cardiomyocytes was 3-fold lower as compared to control cells. Sarcolemmal membrane PLC activity was impaired. Insulin treatment of the diabetic animals resulted in a partial recovery of PA responses. Our results, therefore, identify an important defect in the PA-PLC signaling pathway in diabetic rat cardiomyocytes, which may have significant implications for heart dysfunction during diabetes.

  16. Recent research progress with phospholipase C from Bacillus cereus.

    PubMed

    Lyu, Yan; Ye, Lidan; Xu, Jun; Yang, Xiaohong; Chen, Weiwei; Yu, Hongwei

    2016-01-01

    Phospholipase C (PLC) catalyzes the hydrolysis of phospholipids to produce phosphate monoesters and diacylglycerol. It has many applications in the enzymatic degumming of plant oils. PLC Bc , a bacterial PLC from Bacillus cereus, is an optimal choice for this activity in terms of its wide substrate spectrum, high activity, and approved safety. Unfortunately, its large-scale production and reliable high-throughput screening of PLC Bc remain challenging. Herein, we summarize the research progress regarding PLC Bc with emphasis on the screening methods, expression systems, catalytic mechanisms and inhibitor of PLC Bc . This review hopefully will inspire new achievements in related areas, to promote the sustainable development of PLC Bc and its application.

  17. Adsorption of thorium(IV) from simulated radioactive solutions using a novel electrospun PVA/TiO2/ZnO nanofiber adsorbent functionalized with mercapto groups: Study in single and multi-component systems

    NASA Astrophysics Data System (ADS)

    Alipour, Dariush; Keshtkar, Ali Reza; Moosavian, Mohammad Ali

    2016-03-01

    The novel polyvinyl alcohol/titanium oxide/zinc oxide (PVA/TiO2/ZnO) nanofiber adsorbent functionalized with 3-mercaptopropyltrimethoxysilane (TMPTMS) was prepared by electrospinning method and its potential was investigated for the adsorption of thorium from single and multi-metal aqueous solutions. The prepared adsorbent was characterized by FTIR, SEM and BET analysis. The influences of different operational parameters such as pH, ionic strength, equilibrium time, initial concentration and temperature were studied in batch mode. Investigation of ionic strength effect showed that the addition of NaNO3 to metal solution has a slight effect on the thorium adsorption, whereas pH value has a serious effect on the thorium adsorption at pH values lower than 4. The double-exponential model described the adsorption of Th(IV) ions much better than other kinetic models within both the single and multi-component systems. Among various isotherm models used, the equilibrium data of Th(IV) conformed the Langmuir isotherm in the single system, while those were best fitted by Dubinin-Radushkevich (D-R) isotherm in multi-component system. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° indicated that the nature of adsorption process was spontaneous, endothermic and thermodynamically favored. The inhibitory effect of other metal ions on the adsorption capacity of Th(IV) was in order of Al(III) > Cu(II) > Cd(II) > Ni(II) > U(VI) > Fe(II).

  18. Isolation, amino acid sequence and biological characterization of an "aspartic-49" phospholipase A₂ from Bothrops (Rhinocerophis) ammodytoides venom.

    PubMed

    Clement, Herlinda; Costa de Oliveira, Vanessa; Zamudio, Fernando Z; Lago, Néstor R; Valdez-Cruz, Norma A; Bérnard Valle, Melisa; Hajos, Silvia E; Alagón, Alejandro; Possani, Lourival D; de Roodt, Adolfo R

    2012-12-01

    A phospholipase enzyme was separated by chromatography from the venom of the snake Bothrops (Rhinocerophis) ammodytoides and characterized. The experimentally determined molecular weight was 13,853.65 Da, and the full primary structure was determined by Edman degradation and mass spectrometry analysis. The enzyme contains 122 amino acids residues closely stabilized by 7 disulfide bridges with an isoelectric point of 6.13. Sequence comparison with other known secretory PLA2 shows that the enzyme isolated belongs to the group II, presenting an aspartic acid residue at position 48 (numbered by convention as Asp49) of the active site, and accordingly displaying enzymatic activity. The enzyme corresponds to 3% of the total mass of the venom. The enzyme is mildly toxic to mice. The intravenous LD₅₀ of this phospholipase in CD-1 mice was around 6 μg/g of mouse body weight (more exactly 117 μg/mouse of 20 g) and the minimal mortal dose (MMD) was estimated to be close to 10 μg/g. In contrast, the LD₅₀ of the venom was circa 2 μg/g mouse body weight. Toxicological analyses of the purified enzyme were performed in vitro and in vivo using experimental animals (mice and rats). The enzyme at high doses caused pulmonary congestion, intraperitoneal bleeding, inhibition of clot retraction and muscle tissue alterations with increasing of creatine kinase levels.

  19. Enhanced Design Alternative IV

    SciTech Connect

    N. E. Kramer

    1999-05-18

    This report evaluates Enhanced Design Alternative (EDA) IV as part of the second phase of the License Application Design Selection (LADS) effort. The EDA IV concept was compared to the VA reference design using criteria from the ''Design Input Request for LADS Phase II EDA Evaluations'' (CRWMS M&O 1999b) and (CRWMS M&O 1999f). Briefly, the EDA IV concept arranges the waste packages close together in an emplacement configuration known as ''line load''. Continuous pre-closure ventilation keeps the waste packages from exceeding the 350 C cladding and 200 C (4.3.13) drift wall temperature limits. This EDA concept keeps relatively high, uniform emplacement drift temperatures (post-closure) to drive water away from the repository and thus dry out the pillars between emplacement drifts. The waste package is shielded to permit human access to emplacement drifts and includes an integral filler inside the package to reduce the amount of water that can contact the waste form. Closure of the repository is desired 50 years after first waste is emplaced. Both backfill and a drip shields will be emplaced at closure to improve post-closure performance.

  20. A sputnik IV saga

    NASA Astrophysics Data System (ADS)

    Lundquist, Charles A.

    2009-12-01

    The Sputnik IV launch occurred on May 15, 1960. On May 19, an attempt to deorbit a 'space cabin' failed and the cabin went into a higher orbit. The orbit of the cabin was monitored and Moonwatch volunteer satellite tracking teams were alerted to watch for the vehicle demise. On September 5, 1962, several team members from Milwaukee, Wisconsin made observations starting at 4:49 a.m. of a fireball following the predicted orbit of Sputnik IV. Requests went out to report any objects found under the fireball path. An early morning police patrol in Manitowoc had noticed a metal object on a street and had moved it to the curb. Later the officers recovered the object and had it dropped off at the Milwaukee Journal. The Moonwarch team got the object and reported the situation to Moonwatch Headquarters at the Smithsonian Astrophysical Observatory. A team member flew to Cambridge with the object. It was a solid, 9.49 kg piece of steel with a slag-like layer attached to it. Subsequent analyses showed that it contained radioactive nuclei produced by cosmic ray exposure in space. The scientists at the Observatory quickly recognized that measurements of its induced radioactivity could serve as a calibration for similar measurements of recently fallen nickel-iron meteorites. Concurrently, the Observatory directorate informed government agencies that a fragment from Sputnik IV had been recovered. Coincidently, a debate in the UN Committee on Peaceful Uses of Outer Space involved the issue of liability for damage caused by falling satellite fragments. On September 12, the Observatory delivered the bulk of the fragment to the US Delegation to the UN. Two days later, the fragment was used by US Ambassador Francis Plimpton as an exhibit that the time had come to agree on liability for damage from satellite debris. He offered the Sputnik IV fragment to USSR Ambassador P.D. Morozov, who refused the offer. On October 23, Drs. Alla Massevitch and E.K. Federov of the USSR visited the

  1. Phospholipases of Mineralization Competent Cells and Matrix Vesicles: Roles in Physiological and Pathological Mineralizations

    PubMed Central

    Mebarek, Saida; Abousalham, Abdelkarim; Magne, David; Do, Le Duy; Bandorowicz-Pikula, Joanna; Pikula, Slawomir; Buchet, René

    2013-01-01

    The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A1 or A2, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV) biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM), or participate in

  2. Inhibition of (/sup 3/H)nitrendipine binding by phospholipase A/sub 2/

    SciTech Connect

    Goldman, M.E.; Pisano, J.J.

    1985-10-07

    Phospholipase A/sub 2/ from several sources inhibited (/sup 3/H)nitrendipine binding to membranes from brain, heart and ileal longitudinal muscle. The enzymes from bee venom and Russell's viper venom were most potent, having IC/sub 50/ values of approximately 5 and 14 ng/ml, respectively, in all three membrane preparations. Inhibition of binding by bee venom phospholipase A/sub 2/ was time- and dose-dependent. Mastoparan, a known facilitator of phospholipase A/sub 2/ enzymatic activity, shifted the bee venom phospholipase A/sub 2/ dose-response curve to the left. Pretreatment of brain membranes with bee venom phospholipase A/sub 2/ (10 ng/ml) for 15 min caused a 2-fold increase in the K/sub d/ without changing the B/sub max/ compared with untreated membranes. Extension of the preincubation period to 30 min caused no further increase in the K/sub d/ but significantly decreased the B/sub max/ to 71% the value for untreated membranes. (/sup 3/H)Nitrendipine, preincubated with bee venom phospholipase A/sub 2/, was recovered and found to be fully active, indicating that the phospholipase A/sub 2/ did not modify the ligand. It is concluded that phospholipase A/sub 2/ acts on the membrane at or near the (/sup 3/H)nitrendipine binding site and that phospholipids play a key role in the interactions of 1,4 dihydropyridine calcium channel antagonists with the dihydropyridine binding site. 33 references, 3 figures, 1 table.

  3. Lung mast cells are a source of secreted phospholipases A2

    PubMed Central

    Triggiani, Massimo; Giannattasio, Giorgio; Calabrese, Cecilia; Loffredo, Stefania; Granata, Francescopaolo; Fiorello, Alfonso; Santini, Mario; Gelb, Michael H.; Marone, Gianni

    2009-01-01

    Background Secreted phospholipases A2 (sPLA2s) are released in plasma and other biologic fluids of patients with inflammatory, autoimmune, and allergic diseases. Objective We sought to evaluate sPLA2 activity in the bronchoalveolar lavage fluid (BALF) of asthmatic patients and to examine the expression and release of sPLA2s from primary human lung mast cells (HLMCs). Methods sPLA2 activity was measured in BALF and supernatants of either unstimulated or anti-IgE–activated HLMCs as hydrolysis of oleic acid from radiolabeled Escherichia coli membranes. Expression of sPLA2s was examined by using RT-PCR. The release of cysteinyl leukotriene (LT) C4 was measured by means of enzyme immunoassay. Results Phospholipase A2 (PLA2) activity was higher in the BALF of asthmatic patients than in the control group. BALF PLA2 activity was blocked by the sPLA2 inhibitors dithiothreitol and Me-Indoxam but not by the cytosolic PLA2 inhibitor AZ-1. HLMCs spontaneously released a PLA2 activity that was increased on stimulation with anti-IgE. This PLA2 activity was blocked by dithiothreitol and Me-Indoxam but not by AZ-1. HLMCs constitutively express mRNA for group IB, IIA, IID, IIE, IIF, III, V, X, XIIA, and XIIB sPLA2s. Anti-IgE did not modify the expression of sPLA2s. The cell-impermeable inhibitor Me-Indoxam significantly reduced (up to 40%) the production of LTC4 from anti-IgE–stimulated HLMCs. Conclusions sPLA2 activity is increased in the airways of asthmatic patients. HLMCs express multiple sPLA2s and release 1 or more of them when activated by anti-IgE. The sPLA2s released by mast cells contribute to LTC4 production by acting in an autocrine fashion. Mast cells can be a source of sPLA2s in the airways of asthmatic patients. PMID:19541351

  4. Phospholipase A2 as a point of care alternative to serum amylase and pancreatic lipase

    NASA Astrophysics Data System (ADS)

    Liu, Nathan J.; Chapman, Robert; Lin, Yiyang; Bentham, Andrew; Tyreman, Matthew; Philips, Natalie; Khan, Shahid A.; Stevens, Molly M.

    2016-06-01

    Acute pancreatitis is a relatively common and potentially fatal condition, but the presenting symptoms are non-specific and diagnosis relies largely on the measurement of amylase activity by the hospital clinical laboratory. In this work we develop a point of care test for pancreatitis measuring concentration of secretory phospholipase A2 group IB (sPLA2-IB). Novel antibodies for sPLA2-IB were raised and used to design an ELISA and a lateral flow device (LFD) for the point of care measurement of sPLA2-IB concentration, which was compared to pancreatic amylase activity, lipase activity, and sPLA2-IB activity in 153 serum samples. 98 of these samples were obtained from the pathology unit of a major hospital and classified retrospectively according to presence or absence of pancreatitis, and the remaining 55 were obtained from commercial sources to serve as high lipase (n = 20), CA19-9 positive (n = 15), and healthy (n = 20) controls. sPLA2-IB concentration correlated well with the serum activity of both amylase and lipase, and performed at least as well as either markers in the differentiation of pancreatitis from controls.Acute pancreatitis is a relatively common and potentially fatal condition, but the presenting symptoms are non-specific and diagnosis relies largely on the measurement of amylase activity by the hospital clinical laboratory. In this work we develop a point of care test for pancreatitis measuring concentration of secretory phospholipase A2 group IB (sPLA2-IB). Novel antibodies for sPLA2-IB were raised and used to design an ELISA and a lateral flow device (LFD) for the point of care measurement of sPLA2-IB concentration, which was compared to pancreatic amylase activity, lipase activity, and sPLA2-IB activity in 153 serum samples. 98 of these samples were obtained from the pathology unit of a major hospital and classified retrospectively according to presence or absence of pancreatitis, and the remaining 55 were obtained from commercial sources to

  5. Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications.

    PubMed

    Borrelli, Grazia M; Trono, Daniela

    2015-09-01

    Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

  6. Phospholipase D Signaling Pathways and Phosphatidic Acid as Therapeutic Targets in Cancer

    PubMed Central

    Bruntz, Ronald C.; Lindsley, Craig W.

    2014-01-01

    Phospholipase D is a ubiquitous class of enzymes that generates phosphatidic acid as an intracellular signaling species. The phospholipase D superfamily plays a central role in a variety of functions in prokaryotes, viruses, yeast, fungi, plants, and eukaryotic species. In mammalian cells, the pathways modulating catalytic activity involve a variety of cellular signaling components, including G protein–coupled receptors, receptor tyrosine kinases, polyphosphatidylinositol lipids, Ras/Rho/ADP-ribosylation factor GTPases, and conventional isoforms of protein kinase C, among others. Recent findings have shown that phosphatidic acid generated by phospholipase D plays roles in numerous essential cellular functions, such as vesicular trafficking, exocytosis, autophagy, regulation of cellular metabolism, and tumorigenesis. Many of these cellular events are modulated by the actions of phosphatidic acid, and identification of two targets (mammalian target of rapamycin and Akt kinase) has especially highlighted a role for phospholipase D in the regulation of cellular metabolism. Phospholipase D is a regulator of intercellular signaling and metabolic pathways, particularly in cells that are under stress conditions. This review provides a comprehensive overview of the regulation of phospholipase D activity and its modulation of cellular signaling pathways and functions. PMID:25244928

  7. Phospholipase D signaling pathways and phosphatidic acid as therapeutic targets in cancer.

    PubMed

    Bruntz, Ronald C; Lindsley, Craig W; Brown, H Alex

    2014-10-01

    Phospholipase D is a ubiquitous class of enzymes that generates phosphatidic acid as an intracellular signaling species. The phospholipase D superfamily plays a central role in a variety of functions in prokaryotes, viruses, yeast, fungi, plants, and eukaryotic species. In mammalian cells, the pathways modulating catalytic activity involve a variety of cellular signaling components, including G protein-coupled receptors, receptor tyrosine kinases, polyphosphatidylinositol lipids, Ras/Rho/ADP-ribosylation factor GTPases, and conventional isoforms of protein kinase C, among others. Recent findings have shown that phosphatidic acid generated by phospholipase D plays roles in numerous essential cellular functions, such as vesicular trafficking, exocytosis, autophagy, regulation of cellular metabolism, and tumorigenesis. Many of these cellular events are modulated by the actions of phosphatidic acid, and identification of two targets (mammalian target of rapamycin and Akt kinase) has especially highlighted a role for phospholipase D in the regulation of cellular metabolism. Phospholipase D is a regulator of intercellular signaling and metabolic pathways, particularly in cells that are under stress conditions. This review provides a comprehensive overview of the regulation of phospholipase D activity and its modulation of cellular signaling pathways and functions.

  8. Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications

    PubMed Central

    Borrelli, Grazia M.; Trono, Daniela

    2015-01-01

    Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes. PMID:26340621

  9. Effects of glycosaminoglycans and glycosphingolipids on cytosolic phospholipases A2 from bovine brain.

    PubMed Central

    Yang, H C; Farooqui, A A; Horrocks, L A

    1994-01-01

    Two forms of Ca(2+)-independent cytosolic phospholipase A2 activity (110 kDa and 39 kDa) were found in bovine brain. They were separated by Sephadex G-75 column chromatography. The 110 kDa phospholipase A2 was much more active with phosphatidylethanolamine and was not affected by glycosaminoglycans, whereas the 39 kDa phospholipase A2 was much more active with ethanolamine plasmalogen and was markedly inhibited by glycosaminoglycans. Heparan sulphate was the most potent inhibitor, followed by chondroitin sulphate, hyaluronic acid and heparin. Gangliosides, especially the GM3 ganglioside, but not other glycosphingolipids, inhibited the activity of the 39 kDa phospholipase A2 in a dose-dependent manner. The heat-inactivation profiles of the 110 kDa and 39 kDa phospholipases A2 provide further evidence for the differences between these cytosolic enzymes. Interactions between glycosaminoglycans, gangliosides and phospholipases A2 may be involved in the maintenance of membrane function. PMID:8166664

  10. PMD IVS Analysis Center

    NASA Technical Reports Server (NTRS)

    Tornatore, Vincenza

    2013-01-01

    The main activities carried out at the PMD (Politecnico di Milano DIIAR) IVS Analysis Center during 2012 are briefly higlighted, and future plans for 2013 are sketched out. We principally continued to process European VLBI sessions using different approaches to evaluate possible differences due to various processing choices. Then VLBI solutions were also compared to the GPS ones as well as the ones calculated at co-located sites. Concerning the observational aspect, several tests were performed to identify the most suitable method to achieve the highest possible accuracy in the determination of GNSS (GLOBAL NAVIGATION SATELLITE SYSTEM) satellite positions using the VLBI technique.

  11. Carvacrol attenuates serum levels of total protein, phospholipase A2 and histamine in asthmatic guinea pig

    PubMed Central

    Boskabady, Mohammad Hossein; Jalali, Sedigheh; Yahyazadeh, Negin; Boskabady, Mostafa

    2016-01-01

    Objective: Pharmacological effects of carvacrol such as its anti-inflammatory activities have been shows. In this study the effects of carvacrol on serum levels of total protein (TP), phospholipase A2 (PLA2) and histamine in sensitized guinea pigs was evaluated. Materials and Methods: Sensitized guinea pigs were given drinking water alone (group S), drinking water containing three concentrations of carvacrol (40, 80 and 160 µg/ml) or dexamethasone. Serum levels of TP, PLA2 and histamine were examined I all sensitized groups as well as a non-sensitized control group (n=6 for each group). Results: In sensitized animals, serum levels of TP, PLA2 and histamine were significantly increased compared to control animals (p<0.05 to p<0.001). Significant reduction in TP, PLA2 and histamine levels were observed in treated groups with the two higher concentrations of carvacrol but dexamethasone treatment only decreased serum level of PLA2 (p<0.05 to p<0.001). Although the effect of the lowest concentration of the extract was less than that of dexamethasone (p<0.05 for TP and p<0.001 for PLA2), the effects of the two higher concentrations on PLA2 were similar to dexamethasone and on TP (p<0.01) and histamine (p<0.001) were higher than those of dexamethasone. Conclusion: These results showed that carvacrol reduced serum levels of TP, PLA2 and histamine in sensitized guinea pigs which may indicate an anti-inflammatory effect of this agent in inflammatory disorders such as asthma. PMID:28078244

  12. Division Iv: Stars

    NASA Astrophysics Data System (ADS)

    Corbally, Christopher; D'Antona, Francesca; Spite, Monique; Asplund, Martin; Charbonnel, Corinne; Docobo, Jose Angel; Gray, Richard O.; Piskunov, Nikolai E.

    2012-04-01

    This Division IV was started on a trial basis at the General Assembly in The Hague 1994 and was formally accepted at the Kyoto General Assembly in 1997. Its broad coverage of ``Stars'' is reflected in its relatively large number of Commissions and so of members (1266 in late 2011). Its kindred Division V, ``Variable Stars'', has the same history of its beginning. The thinking at the time was to achieve some kind of balance between the number of members in each of the 12 Divisions. Amid the current discussion of reorganizing the number of Divisions into a more compact form it seems advisable to make this numerical balance less of an issue than the rationalization of the scientific coverage of each Division, so providing more effective interaction within a particular field of astronomy. After all, every star is variable to a certain degree and such variability is becoming an ever more powerful tool to understand the characteristics of every kind of normal and peculiar star. So we may expect, after hearing the reactions of members, that in the restructuring a single Division will result from the current Divisions IV and V.

  13. Identifying New Drug Targets for Potent Phospholipase D Inhibitors: Combining Sequence Alignment, Molecular Docking, and Enzyme Activity/Binding Assays.

    PubMed

    Djakpa, Helene; Kulkarni, Aditya; Barrows-Murphy, Scheneque; Miller, Greg; Zhou, Weihong; Cho, Hyejin; Török, Béla; Stieglitz, Kimberly

    2016-05-01

    Phospholipase D enzymes cleave phospholipid substrates generating choline and phosphatidic acid. Phospholipase D from Streptomyces chromofuscus is a non-HKD (histidine, lysine, and aspartic acid) phospholipase D as the enzyme is more similar to members of the diverse family of metallo-phosphodiesterase/phosphatase enzymes than phospholipase D enzymes with active site HKD repeats. A highly efficient library of phospholipase D inhibitors based on 1,3-disubstituted-4-amino-pyrazolopyrimidine core structure was utilized to evaluate the inhibition of purified S. chromofuscus phospholipase D. The molecules exhibited inhibition of phospholipase D activity (IC50 ) in the nanomolar range with monomeric substrate diC4 PC and micromolar range with phospholipid micelles and vesicles. Binding studies with vesicle substrate and phospholipase D strongly indicate that these inhibitors directly block enzyme vesicle binding. Following these compelling results as a starting point, sequence searches and alignments with S. chromofuscus phospholipase D have identified potential new drug targets. Using AutoDock, inhibitors were docked into the enzymes selected from sequence searches and alignments (when 3D co-ordinates were available) and results analyzed to develop next-generation inhibitors for new targets. In vitro enzyme activity assays with several human phosphatases demonstrated that the predictive protocol was accurate. The strategy of combining sequence comparison, docking, and high-throughput screening assays has helped to identify new drug targets and provided some insight into how to make potential inhibitors more specific to desired targets.

  14. Minimal oxidation and storage of low density lipoproteins result in an increased susceptibility to phospholipid hydrolysis by phospholipase A2.

    PubMed

    Eckey, R; Menschikowski, M; Lattke, P; Jaross, W

    1997-07-25

    In vitro-studies have shown that phospholipid hydrolysis of low density lipoproteins (LDL) by bee venom or porcine pancreatic phospholipase A2 (PLA2) leads to an increased uptake of these lipoproteins by macrophages transforming them into foam cells. Recently, a secretory phospholipase A2, group II, was detected in human atherosclerotic plaques. In order to investigate the role of this enzyme in the pathogenesis of atherosclerosis, a structurally identical human secretory PLA2 was purified from the medium of HepG2 cells stimulated with interleukin-6 and tumor necrosis factor-alpha. The activity of the purified enzyme towards the phospholipids of native and modified low density lipoproteins was compared with the activity towards Escherichia coli-membranes and other phospholipid substrates. Compared to E. coli-membranes, native LDL proved to be a poor substrate for group II PLA2. After mild oxidation induced by copper ions or by 2,2-azobis(2-amidinopropane) (AAPH), the susceptibility of LDL to phospholipid hydrolysis was found to be increased by 25 and 23%, respectively, whereas extensive copper-mediated oxidation caused a decreased hydrolysis. Aging of LDL at 6 degrees C for weeks or at 37 degrees C for hours resulted in an increase in PLA2-catalyzed phospholipid hydrolysis of up to 26-fold. LDL protected from oxidation by probucol during aging showed a lesser increase in susceptibility to phospholipid hydrolysis. Our results suggest that PLA2, group II, can increase the atherogenicity of LDL by its ability to hydrolyze the phospholipids of these lipoproteins, especially after modifications that are likely to occur in vivo.

  15. Lithium activates brain phospholipase A2 and improves memory in rats: implications for Alzheimer's disease.

    PubMed

    Mury, Fábio B; da Silva, Weber C; Barbosa, Nádia R; Mendes, Camila T; Bonini, Juliana S; Sarkis, Jorge Eduardo Souza; Cammarota, Martin; Izquierdo, Ivan; Gattaz, Wagner F; Dias-Neto, Emmanuel

    2016-10-01

    Phospholipase A2 (Pla2) is required for memory retrieval, and its inhibition in the hippocampus has been reported to impair memory acquisition in rats. Moreover, cognitive decline and memory deficits showed to be reduced in animal models after lithium treatment, prompting us to evaluate possible links between Pla2, lithium and memory. Here, we evaluated the possible modulation of Pla2 activity by a long-term treatment of rats with low doses of lithium and its impact in memory. Wistar rats were trained for the inhibitory avoidance task, treated with lithium for 100 days and tested for perdurability of long-term memory. Hippocampal samples were used for quantifying the expression of 19 brain-expressed Pla2 genes and for evaluating the enzymatic activity of Pla2 using group-specific radio-enzymatic assays. Our data pointed to a significant perdurability of long-term memory, which correlated with increased transcriptional and enzymatic activities of certain members of the Pla2 family (iPla2 and sPla2) after the chronic lithium treatment. Our data suggest new possible targets of lithium, add more information on its pharmacological activity and reinforce the possible use of low doses of lithium for the treatment of neurodegenerative conditions such as the Alzheimer's disease.

  16. Quantum-dynamical picture of a multistep enzymatic process: reaction catalyzed by phospholipase A(2).

    PubMed Central

    Bała, P; Grochowski, P; Nowiński, K; Lesyng, B; McCammon, J A

    2000-01-01

    A quantum-classical molecular dynamics model (QCMD), applying explicit integration of the time-dependent Schrödinger equation (QD) and Newtonian equations of motion (MD), is presented. The model is capable of describing quantum dynamical processes in complex biomolecular systems. It has been applied in simulations of a multistep catalytic process carried out by phospholipase A(2) in its active site. The process includes quantum-dynamical proton transfer from a water molecule to histidine localized in the active site, followed by a nucleophilic attack of the resulting OH(-) group on a carbonyl carbon atom of a phospholipid substrate, leading to cleavage of an adjacent ester bond. The process has been simulated using a parallel version of the QCMD code. The potential energy function for the active site is computed using an approximate valence bond (AVB) method. The dynamics of the key proton is described either by QD or classical MD. The coupling between the quantum proton and the classical atoms is accomplished via Hellmann-Feynman forces, as well as the time dependence of the potential energy function in the Schrödinger equation (QCMD/AVB model). Analysis of the simulation results with an Advanced Visualization System revealed a correlated rather than a stepwise picture of the enzymatic process. It is shown that an sp(2)--> sp(3) configurational change at the substrate carbonyl carbon is mostly responsible for triggering the activation process. PMID:10968989

  17. Comparative proteomics and subtyping of venom phospholipases A2 and disintegrins of Protobothrops pit vipers.

    PubMed

    Tsai, Inn-Ho; Chen, Yi-Hsuan; Wang, Ying-Ming

    2004-10-01

    To explore the venom diversity and systematics of pit vipers under the genus Protobothrops, the venom phospholipases A2 (PLA2s) of P. mangshanensis, P. elegans and P. tokarensis were purified and characterized for the first time. The results were compared with the corresponding venom data of other co-generic species including P. mucrosquamatus, P. flavoviridis and P. jerdonii. Based on sequence features at the N-terminal regions, we identified five PLA2 subtypes, i.e., the Asp49-PLA2s with N6, E6 or R6 substitution and the Lys49-PLA2. However, not all subtypes were expressed in each of the species. Venom N6-PLA2s from P. mangshanensis and P. tokarensis venom were weakly neurotoxic toward chick biventer cervicis tissue preparations. The venoms of P. tokarensis and P. flavoviridis contained identical PLA2 isoforms. In most Protobothrop disintegrins, sequences flanking the RGD-motif are conserved. Phylogenetic analyses based on amino acid sequences of both families of the acidic PLA2s and the disintegrins clarify that these species could belong to a monophyletic group.

  18. Structure of a king cobra phospholipase A2 determined from a hemihedrally twinned crystal.

    PubMed

    Xu, Sujuan; Gu, Lichuan; Wang, Qiuyan; Shu, Yuyan; Song, Shiying; Lin, Zhengjiong

    2003-09-01

    An acidic PLA(2) (OH APLA(2)-II) from the venom of Ophiophagus hannah (king cobra) shows greater phospholipase A(2) activity and weaker cardiotoxic and myotoxic activity than a homologous acidic PLA(2) from the same venom. The crystal of the enzyme belongs to space group P6(3). The crystals are invariably hemihedrally twinned, exhibiting perfect 622 Laue symmetry. The structure was determined by molecular replacement and refined using a hemihedral twinning program at 2.1 A resolution. The final model has reasonable stereochemistry and a crystallographic R factor of 19.5% (R(free) = 21.5%). The structure reveals the molecular arrangement and the mode of twinning. There are six independent molecules in the asymmetric unit. Owing to the presence of a non-crystallographic twofold parallel to the hemihedral twinning twofold, the molecular packing in the twinned crystal is extremely similar to that in an untwinned crystal for four of the molecules. This unique molecular arrangement may be related to the difficulty in recognizing the twinning. The structure was compared with the previously determined structure of a homologous acidic PLA(2) from the same source. The comparison shows structural changes that might be implicated in the increased catalytic activity and weakened toxicity.

  19. Effects of smoke inhalation on surfactant phospholipids and phospholipase A2 activity in the mouse lung.

    PubMed Central

    Oulton, M.; Moores, H. K.; Scott, J. E.; Janigan, D. T.; Hajela, R.

    1991-01-01

    The effects of smoke inhalation on the pulmonary surfactant system were examined in mice exposed for 30 minutes to smoke generated from the burning of polyurethane foam. At 8 or 12 hours after exposure, surfactants were isolated separately from lung lavage (extracellular surfactant) and residual lung tissue (intracellular surfactant) for phospholipid analysis. Calcium-dependent phospholipase A2 (PLA2) was measured on a microsomal fraction prepared from the tissue homogenate. Smoke inhalation produced a twofold increase in extracellular surfactant total phospholipid. While there was no change in the total phospholipid or phosphatidylcholine (PC) content of the intracellular surfactant, smoke inhalation significantly decreased the disaturated species of PC (DSPC). The specific activity of PLA2 was reduced by more than 50% in both groups of exposed mice. Smoke inhalation appears to result in selective depletion of the DSPC of intracellular surfactant and PLA2 involved in its synthesis. This depletion may be compensated for by increased secretion or slower breakdown of the material present in the extracellular compartment. Images Figure 1 PMID:1987765

  20. Phospholipase D affects translocation of NPR1 to the nucleus in Arabidopsis thaliana

    PubMed Central

    Janda, Martin; Šašek, Vladimír; Chmelařová, Hana; Andrejch, Jan; Nováková, Miroslava; Hajšlová, Jana; Burketová, Lenka; Valentová, Olga

    2015-01-01

    Phytohormone salicylic acid (SA) is a crucial component of plant-induced defense against biotrophic pathogens. Although the key players of the SA pathway are known, there are still gaps in the understanding of the molecular mechanism and the regulation of particular steps. In our previous research, we showed in Arabidopsis suspension cells that n-butanol, which specifically modulates phospholipase D activity, significantly suppresses the transcription of the pathogenesis related (PR-1) gene, which is generally accepted as the SA pathway marker. In the presented study, we have investigated the site of n-butanol action in the SA pathway. We were able to show in Arabidopsis plants treated with SA that n-butanol inhibits the transcription of defense genes (PR-1, WRKY38). Fluorescence microscopy of Arabidopsis thaliana mutants expressing 35S::NPR1-GFP (nonexpressor pathogenesis related 1) revealed significantly decreased nuclear localization of NPR1 in the presence of n-butanol. On the other hand, n-butanol did not decrease the nuclear localization of NPR1 in 35S::npr1C82A-GFP and 35S::npr1C216A-GFP mutants constitutively expressing NPR1 monomers. Mass spectrometric analysis of plant extracts showed that n-butanol significantly changes the metabolic fingerprinting while t-butanol had no effect. We found groups of the plant metabolites, influenced differently by SA and n-butanol treatment. Thus, we proposed several metabolites as markers for n-butanol action. PMID:25741350

  1. Purification and characterization of a phospholipase A2-IIA from common stingray (Dasyatis pastinaca) intestine.

    PubMed

    Ben Bacha, Abir; Daihan, Sooad K; Moubayed, Nadine M S; Mejdoub, Hafedh

    2013-06-01

    A phospholipase A2 belonging to IIA group secretory PLA2 was isolated and purified to homogeneity from the intestine of common stingray (Dasyatis pastinaca) using acidic treatment (pH 1.5) and ammonium sulphate precipitation methods combined with single-column ion-exchange chromatography. The purified enzyme was found to be a glycosylated monomeric protein with a molecular mass of about 14 kDa. The stingray sPLA2-IIA had optimum activity at 45 degrees C, unlike known mammalian PLA2-IIAs, which show optimum activity at 37 degrees C. The purified enzyme exhibited a specific activity of 290 U/mg at optimal conditions (pH 9.5 and 45 degrees C) in the presence of 6 mM NaDC and 8 mM CaCl2 with egg yolk as substrate. The NH2-terminal sequence of the enzyme and some protein fragments obtained from its tryptic digestion were also determined. All sequences obtained were similar to those of sPLA2-IIA. The enzyme also showed good stability in the presence of organic solvents, acidic and alkaline pH media and high temperature conditions. Thus, the purified enzyme exhibited a number of unique and promising properties, making it a potential possible candidate for future applications in the treatment of phospholipid-rich industrial effluents and synthesis of useful preparations for the food production and processing industry.

  2. 78 FR 2390 - CSOLAR IV South, LLC, Wistaria Ranch Solar, LLC, CSOLAR IV West, LLC, CSOLAR IV North, LLC v...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-11

    ... Energy Regulatory Commission CSOLAR IV South, LLC, Wistaria Ranch Solar, LLC, CSOLAR IV West, LLC, CSOLAR IV North, LLC v. California Independent System Operator Corporation; Notice of Complaint Take notice... IV South, LLC, Wistaria Ranch Solar, LLC, CSOLAR IV West, LLC and CSOLAR IV North, LLC...

  3. Kinetic Evaluation of Cell Membrane Hydrolysis during Apoptosis by Human Isoforms of Secretory Phospholipase A2*

    PubMed Central

    Olson, Erin D.; Nelson, Jennifer; Griffith, Katalyn; Nguyen, Thaothanh; Streeter, Michael; Wilson-Ashworth, Heather A.; Gelb, Michael H.; Judd, Allan M.; Bell, John D.

    2010-01-01

    Some isoforms of secretory phospholipase A2 (sPLA2) distinguish between healthy and damaged or apoptotic cells. This distinction reflects differences in membrane physical properties. Because various sPLA2 isoforms respond differently to properties of artificial membranes such as surface charge, they should also behave differently as these properties evolve during a dynamic physiological process such as apoptosis. To test this idea, S49 lymphoma cell death was induced by glucocorticoid (6–48 h) or calcium ionophore. Rates of membrane hydrolysis catalyzed by various concentrations of snake venom and human groups IIa, V, and X sPLA2 were compared after each treatment condition. The data were analyzed using a model that evaluates the adsorption of enzyme to the membrane surface and subsequent binding of substrate to the active site. Results were compared temporally to changes in membrane biophysics and composition. Under control conditions, membrane hydrolysis was confined to the few unhealthy cells present in each sample. Increased hydrolysis during apoptosis and necrosis appeared to reflect substrate access to adsorbed enzyme for the snake venom and group X isoforms corresponding to weakened lipid-lipid interactions in the membrane. In contrast, apoptosis promoted initial adsorption of human groups V and IIa concurrent with phosphatidylserine exposure on the membrane surface. However, this observation was inadequate to explain the behavior of the groups V and IIa enzymes toward necrotic cells where hydrolysis was reduced or absent. Thus, a combination of changes in cell membrane properties during apoptosis and necrosis capacitates the cell for hydrolysis differently by each isoform. PMID:20139082

  4. Cytosolic phospholipase A2 α has a crucial role in the pathogenesis of DSS-induced colitis in mice.

    PubMed

    Rosengarten, Marina; Hadad, Nurit; Solomonov, Yulia; Lamprecht, Sergio; Levy, Rachel

    2016-02-01

    Colitis, an inflammation of the colon, is a well-characterized massive tissue injury. Cytosolic phospholipase A2 α (cPLA2 α) upregulation plays an important role in the development of several inflammatory diseases. The aim of the present study was to define the role of cPLA2 α upregulation in the development of colitis. We used a mouse model of dextran sulfate sodium induced colitis. Immunoblotting analysis showed that cPLA2 α and NF-κB were upregulated and activated in the colon from day 2 of colitis induction. This molecular event preceded the development of the disease, as determined by Disease Activity Index score, body weight, colon length, and the expression of colonic inflammatory markers, including neutrophil infiltration detected by myeloperoxidase and by NIMP-R14, ICAM-1, COX-2, iNOS upregulation and LTB4 and TNF-α secretion. Prevention of cPLA2 α upregulation and activity in the colon by i.v. administration of specific antisense oligonucleotides against cPLA2 α 1 day prior and every day of exposure to dextran sulfate sodium significantly impeded the development of the disease and prevented NF-κB activation, neutrophils infiltration into the colonic mucosa, and expression of proinflammatory proteins in the colon. Our results demonstrate a critical role of cPLA2 α upregulation in inflammation and development of murine colitis.

  5. Phospholipase cbeta is critical for T cell chemotaxis.

    PubMed

    Bach, Tami L; Chen, Qing-Min; Kerr, Wesley T; Wang, Yanfeng; Lian, Lurong; Choi, John K; Wu, Dianqing; Kazanietz, Marcelo G; Koretzky, Gary A; Zigmond, Sally; Abrams, Charles S

    2007-08-15

    Chemokines acting through G protein-coupled receptors play an essential role in the immune response. PI3K and phospholipase C (PLC) are distinct signaling molecules that have been proposed in the regulation of chemokine-mediated cell migration. Studies with knockout mice have demonstrated a critical role for PI3K in G(alphai) protein-coupled receptor-mediated neutrophil and lymphocyte chemotaxis. Although PLCbeta is not essential for the chemotactic response of neutrophils, its role in lymphocyte migration has not been clearly defined. We compared the chemotactic response of peripheral T cells derived from wild-type mice with mice containing loss-of-function mutations in both of the two predominant lymphocyte PLCbeta isoforms (PLCbeta2 and PLCbeta3), and demonstrate that loss of PLCbeta2 and PLCbeta3 significantly impaired T cell migration. Because second messengers generated by PLCbeta lead to a rise in intracellular calcium and activation of PKC, we analyzed which of these responses was critical for the PLCbeta-mediated chemotaxis. Intracellular calcium chelation decreased the chemotactic response of wild-type lymphocytes, but pharmacologic inhibition of several PKC isoforms had no effect. Furthermore, calcium efflux induced by stromal cell-derived factor-1alpha was undetectable in PLCbeta2beta3-null lymphocytes, suggesting that the migration defect is due to the impaired ability to increase intracellular calcium. This study demonstrates that, in contrast to neutrophils, phospholipid second messengers generated by PLCbeta play a critical role in T lymphocyte chemotaxis.

  6. Effects of Phospholipase C on Fusarium graminearum Growth and Development.

    PubMed

    Zhu, Qili; Zhou, Benguo; Gao, Zhengliang; Liang, Yuancun

    2015-12-01

    Phospholipase C (PLC) plays important roles in regulating various biological processes in eukaryotes. Currently, little is known about the function of PLC in filamentous fungi, especially the plant pathogenic fungi. Fusarium graminearum is the causal agent of Fusarium head blight in many cereal crops. BLAST search revealed that Fusarium genome contains six FgPLC genes. Using quantitative RT-PCR, different FgPLC gene expressions in mycelia were analyzed. To investigate the role of FgPLC in F. graminearum biology, a pharmacological study using a known inhibitor of PLC (U73122) was conducted. Results showed that inhibition of FgPLC resulted in significant alterations of mycelial growth, conidiation, conidial germination, perithecium formation, and expressions of Tri5 and Tri6 genes. As expected, the treatment of F. graminearum with U73343, an inactive analog of U73122, showed no effect on F. graminearum biology. Our results suggested strongly that FgPLC plays important roles in F. graminearum growth and development.

  7. Activation of Phospholipase A by Plant Defense Elicitors.

    PubMed Central

    Chandra, S.; Heinstein, P. F.; Low, P. S.

    1996-01-01

    Participation of phospholipase A (PLase A) in plant signal transduction has been documented for auxin stimulation of growth but not for elicitation of any plant defense response. In this paper, we report two independent assays for monitoring PLase A induction in plant cells and have used these assays to evaluate whether transduction of defense-related signals might require PLase A activation. Oligogalacturonic acid, a potent elicitor of the soybean (Glycine max) H2O2 burst, was unable to stimulate endogenous PLase A, suggesting that PLase A activation is not an obligate intermediate in the oligogalacturonic acid-induced burst pathway. In contrast, harpin and an extract from the pathogenic fungus Verticillium dahliae both stimulated the oxidative burst and promoted a rapid increase in PLase A activity. To evaluate the possible role of this inducible PLase A activity in transducing the oxidative burst, we tested the effect of chlorpromazine-HCl, a PLase A inhibitor on elicitor-stimulated burst activity. Pretreatment with chloropromazine was found to inhibit the H2O2 burst triggered by V. dahliae extract at the same concentration at which it blocked PLase A activation. In contrast, neither the harpin- nor oligogalacturonic acid-induced burst was altered by addition of chlorpromazine. These data suggest that PLase A stimulation may be important in certain elicitor-induced oxidative bursts (e.g. V. dahliae) and that other elicitors such as oligogalacturonic acid and harpin must operate through independent signaling intermediates to activate the same defense response. PMID:12226235

  8. Impairment of kindling development in phospholipase Cγ1 heterozygous mice

    PubMed Central

    He, Xiao Ping; Wen, Renren; McNamara, James O

    2014-01-01

    Summary Objective Elucidating molecular mechanisms underlying limbic epileptogenesis may reveal novel targets for preventive therapy. Studies of TrkB mutant mice led us to hypothesize that signaling through a specific phospholipase (PLC), PLCγ1, promoted development of kindling. Methods To test this hypothesis, we examined the development of kindling in PLCγ1 heterozygous mice. We also examined the cellular and subcellular location of PLCγ1 in adult wild type mice. Results The development of kindling was impaired in PLCγ1 heterozygous mice compared to wild type controls. PLCγ1 immunoreactivity was localized to the soma and dendrites of both excitatory and inhibitory neurons in hippocampus of adult mice. Significance This study implicates PLCγ1 signaling as the dominant pathway by which TrkB activation promotes limbic epileptogenesis. Its cellular localization places PLCγ1 in a position to modify the efficacy of both excitatory and inhibitory synaptic transmission. These findings advance PLCγ1 as a novel target for therapies aimed at preventing temporal lobe epilepsy induced by status epilepticus. PMID:24502564

  9. Variable substrate preference among phospholipase D toxins from sicariid spiders

    DOE PAGES

    Lajoie, Daniel M.; Roberts, Sue A.; Zobel-Thropp, Pamela A.; ...

    2015-03-09

    Venoms of the sicariid spiders contain phospholipase D enzyme toxins that can cause severe dermonecrosis and even death in humans. These enzymes convert sphingolipid and lysolipid substrates to cyclic phosphates by activating a hydroxyl nucleophile present in both classes of lipid. The most medically relevant substrates are thought to be sphingomyelin and/or lysophosphatidylcholine. To better understand the substrate preference of these toxins, we used 31P NMR to compare the activity of three related but phylogenetically diverse sicariid toxins against a diverse panel of sphingolipid and lysolipid substrates. Two of the three showed significantly faster turnover of sphingolipids over lysolipids, andmore » all three showed a strong preference for positively charged (choline and/or ethanolamine) over neutral (glycerol and serine) headgroups. Strikingly, however, the enzymes vary widely in their preference for choline, the headgroup of both sphingomyelin and lysophosphatidylcholine, versus ethanolamine. An enzyme from Sicarius terrosus showed a strong preference for ethanolamine over choline, whereas two paralogous enzymes from Loxosceles arizonica either preferred choline or showed no significant preference. Intrigued by the novel substrate preference of the Sicarius enzyme, we solved its crystal structure at 2.1 Å resolution. Lastly, the evolution of variable substrate specificity may help explain the reduced dermonecrotic potential of some natural toxin variants, because mammalian sphingolipids use primarily choline as a positively charged headgroup; it may also be relevant for sicariid predatory behavior, because ethanolamine-containing sphingolipids are common in insect prey.« less

  10. Targeting NADPH oxidase and phospholipases A2 in Alzheimer's disease.

    PubMed

    Simonyi, Agnes; He, Yan; Sheng, Wenwen; Sun, Albert Y; Wood, W Gibson; Weisman, Gary A; Sun, Grace Y

    2010-06-01

    Alzheimer's disease (AD) is marked by an increase in the production of extracellular beta amyloid plaques and intracellular neurofibrillary tangles associated with a decline in brain function. Increases in oxidative stress are regarded as an early sign of AD pathophysiology, although the source of reactive oxygen species (ROS) and the mechanism(s) whereby beta amyloid peptides (Abeta) impact oxidative stress have not been adequately investigated. Recent studies provide strong evidence for the involvement of NADPH oxidase and its downstream oxidative signaling pathways in the toxic effects elicited by Abeta. ROS produced by NADPH oxidase activate multiple signaling pathways leading to neuronal excitotoxicity and glial cell-mediated inflammation. This review describes recent studies demonstrating the neurotoxic effects of Abeta in conjunction with ROS produced by NADPH oxidase and the downstream pathways leading to activation of cytosolic phospholipase A(2) (PLA(2)) and secretory PLA(2). In addition, this review also describes recent studies using botanical antioxidants to protect against oxidative damage associated with AD. Investigating the metabolic and signaling pathways involving Abeta NADPH oxidase and PLA(2) can help understand the mechanisms underlying the neurodegenerative effects of oxidative stress in AD. This information should provide new therapeutic approaches for prevention of this debilitating disease.

  11. Targeting phospholipase D in cancer, infection and neurodegenerative disorders.

    PubMed

    Brown, H Alex; Thomas, Paul G; Lindsley, Craig W

    2017-02-17

    Lipid second messengers have essential roles in cellular function and contribute to the molecular mechanisms that underlie inflammation, malignant transformation, invasiveness, neurodegenerative disorders, and infectious and other pathophysiological processes. The phospholipase D (PLD) isoenzymes PLD1 and PLD2 are one of the major sources of signal-activated phosphatidic acid (PtdOH) generation downstream of a variety of cell-surface receptors, including G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and integrins. Recent advances in the development of isoenzyme-selective PLD inhibitors and in molecular genetics have suggested that PLD isoenzymes in mammalian cells and pathogenic organisms may be valuable targets for the treatment of several human diseases. Isoenzyme-selective inhibitors have revealed complex inter-relationships between PtdOH biosynthetic pathways and the role of PtdOH in pathophysiology. PLD enzymes were once thought to be undruggable owing to the ubiquitous nature of PtdOH in cell signalling and concerns that inhibitors would be too toxic for use in humans. However, recent promising discoveries suggest that small-molecule isoenzyme-selective inhibitors may provide novel compounds for a unique approach to the treatment of cancers, neurodegenerative disorders and other afflictions of the central nervous system, and potentially serve as broad-spectrum antiviral and antimicrobial therapeutics.

  12. Phospholipase C activation is required for cardioprotection by ethanol consumption

    PubMed Central

    Miyamae, Masami; Domae, Naochika; Zhou, Hui-Zhong; Sugioka, Shingo; Diamond, Ivan; Figueredo, Vincent M

    2003-01-01

    Regular alcohol consumption decreases the incidence of myocardial infarction (MI) and improves post-MI survival. It has previously been reported that chronic ethanol exposure induces long-term protection against cardiac ischemia/reperfusion injury, which improves myocardial recovery after MI. Chronic cardioprotection by ethanol requires the activation of myocyte adenosine A1 receptors and sustained intramyocyte translocation of epsilon protein kinase C. A1 receptors activate phospholipase C (PLC). In the present paper, the role of PLC in mediating ethanol’s protective effect against ischemia/reperfusion injury is investigated. Isolated hearts from guinea pigs fed 2.5% ethanol in their water for four months were subjected to ischemia/reperfusion. Hearts from ethanol-treated animals showed improved recovery of left ventricular developed pressure compared with controls (61% versus 38% of baseline, respectively; P<0.05) and decreased necrosis, assessed by the release of creatine kinase (263±18 U/mL × g dry weight versus 360±24 U/mL × g dry weight, respectively; P<0.05). Ethanol protection was abolished by the PLC antagonist, U-73122 (50 nM). These findings suggest that PLC activation is required for ethanol cardioprotection against ischemia/reperfusion injury. PMID:19649218

  13. Therapeutic inhibition of phospholipase D1 suppresses hepatocellular carcinoma.

    PubMed

    Xiao, Junjie; Sun, Qi; Bei, Yihua; Zhang, Ling; Dimitrova-Shumkovska, Jasmina; Lv, Dongchao; Yang, Yuefeng; Cao, Yan; Zhao, Yingying; Song, Meiyi; Song, Yang; Wang, Fei; Yang, Changqing

    2016-07-01

    Hepatocellular carcinoma (HCC) represents a leading cause of deaths worldwide. Novel therapeutic targets for HCC are needed. Phospholipase D (PD) is involved in cell proliferation and migration, but its role in HCC remains unclear. In the present study, we show that PLD1, but not PLD2, was overexpressed in HCC cell lines (HepG2, Bel-7402 and Bel-7404) compared with the normal human L-02 hepatocytes. PLD1 was required for the proliferation, migration and invasion of HCC cells without affecting apoptosis and necrosis, and PLD1 overexpression was sufficient to promote those effects. By using HCC xenograft models, we demonstrated that therapeutic inhibition of PLD1 attenuated tumour growth and epithelial-mesenchymal transition (EMT) in HCC mice. Moreover, PLD1 was found to be highly expressed in tumour tissues of HCC patients. Finally, mTOR (mechanistic target of rapamycin) and Akt (protein kinase B) were identified as critical pathways responsible for the role of PLD1 in HCC cells. Taken together, the present study indicates that PLD1 activation contributes to HCC development via regulation of the proliferation, migration and invasion of HCC cells, as well as promoting the EMT process. These observations suggest that inhibition of PLD1 represents an attractive and novel therapeutic modality for HCC.

  14. The galactolipase activity of Fusarium solani (phospho)lipase.

    PubMed

    Jallouli, Raida; Othman, Houcemeddine; Amara, Sawsan; Parsiegla, Goetz; Carriere, Frédéric; Srairi-Abid, Najet; Gargouri, Youssef; Bezzine, Sofiane

    2015-03-01

    The purified (phospho)lipase of Fusarium solani (FSL), was known to be active on both triglycerides and phospholipids. This study aimed at assessing the potential of this enzyme in hydrolyzing galactolipids. FSL was found to hydrolyze at high rates of synthetic medium chains monogalactosyldiacylglycerol (4658±146U/mg on DiC8-MGDG) and digalactosyldiacylglycerol (3785±83U/mg on DiC8-DGDG) and natural long chain monogalactosyldiacylglycerol extracted from leek leaves (991±85U/mg). It is the microbial enzyme with the highest activity on galactolipids identified so far with a level of activity comparable to that of pancreatic lipase-related protein 2. FSL maximum activity on galactolipids was measured at pH8. The analysis of the hydrolysis product of natural MGDG from leek showed that FSL hydrolyzes preferentially the ester bond at the sn-1 position of galactolipids. To investigate the structure-activity relationships of FSL, a 3D model of this enzyme was built. In silico docking of medium chains MGDG and DGDG and phospholipid in the active site of FSL reveals structural solutions which are in concordance with in vitro tests.

  15. Acidification in the epidermis and the role of secretory phospholipases

    PubMed Central

    Chan, Aegean

    2011-01-01

    The function of the epidermis is to form an effective barrier between the dry, external environment and the interior of the body. The barrier specifically resides in the extracellular lipid membranes of the stratum corneum (SC) and an acidic pH is necessary to maintain its competency against various insults. The purpose of this review is to explore the mechanisms which are postulated to contribute to the acidification of the stratum corneum, including both exogenous and endogenous sources. However, recent research as pointed to several endogenous mechanisms as the major source of acidification, including a sodium/proton pump (NHE1) and free fatty acid conversion from phospholipids by secretory phospholipase A2 (sPLA2). sPLA2 has been shown to play a central role in the formation of the SC “acid mantle” in the early maturation of the epidermis postnatally. Many aspects of this enzyme family are complex and still being elucidated in research and the most recent findings on the localization and functions of sPL A2-IB, -IIA, -IIC, -IID, -IIE, -IIF, -III, -V, -X and -XII in the epidermis are presented here. Given their role in inflammatory dermatoses, such as psoriasis and atopic dermatitis, understanding this complex enzyme family can lead to novel, life-changing therapies. PMID:21695017

  16. Interfacial Catalysis: The Mechanism of Phospholipase A2

    PubMed Central

    Scott, David L.; White, Steven P.; Otwinowski, Zbyszek; Yuan, Wei; Gelb, Michael H.; Sigler, Paul B.

    2012-01-01

    A chemical description of the action of phospholipase A2 (PLA2) can now be inferred with confidence from three high-resolution x-ray crystal structures. The first is the structure of the PLA2 from the venom of the Chinese cobra (Naja naja atra) in a complex with a phosphonate transition-state analogue. This enzyme is typical of a large, well-studied homologous family of PLA2s. The second is a similar complex with the evolutionarily distant bee-venom PLA2. The third structure is the uninhibited PLA2 from Chinese cobra venom. Despite the different molecular architectures of the cobra and bee-venom PLA2s, the transition-state analogue interacts in a nearly identical way with the catalytic machinery of both enzymes. The disposition of the fatty-acid side chains suggests a common access route of the substrate from its position in the lipid aggregate to its productive interaction with the active site. Comparison of the cobra-venom complex with the uninhibited enzyme indicates that optimal binding and catalysis at the lipid-water interface is due to facilitated substrate diffusion from the interfacial binding surface to the catalytic site rather than an allosteric change in the enzyme’s structure. However, a second bound calcium ion changes its position upon the binding of the transition-state analogue, suggesting a mechanism for augmenting the critical electrophile. PMID:2274785

  17. Identification of a new phospholipase D in Carica papaya latex.

    PubMed

    Abdelkafi, Slim; Abousalham, Abdelkarim; Fendri, Imen; Ogata, Hiroyuki; Barouh, Nathalie; Fouquet, Benjamin; Scheirlinckx, Frantz; Villeneuve, Pierre; Carrière, Frédéric

    2012-05-15

    Phospholipase D (PLD) is a lipolytic enzyme involved in signal transduction, vesicle trafficking and membrane metabolism. It catalyzes the hydrolysis and transphosphatidylation of glycerophospholipids at the terminal phosphodiester bond. The presence of a PLD in the latex of Carica papaya (CpPLD1) was demonstrated by transphosphatidylation of phosphatidylcholine (PtdCho) in the presence of 2% ethanol. Although the protein could not be purified to homogeneity due to its presence in high molecular mass aggregates, a protein band was separated by SDS-PAGE after SDS/chloroform-methanol/TCA-acetone extraction of the latex insoluble fraction. This material was digested with trypsin and the amino acid sequences of the tryptic peptides were determined by micro-LC/ESI/MS/MS. These sequences were used to identify a partial cDNA (723 bp) from expressed sequence tags (ESTs) of C. papaya. Based upon EST sequences, a full-length gene was identified in the genome of C. papaya, with an open reading frame of 2424 bp encoding a protein of 808 amino acid residues, with a theoretical molecular mass of 92.05 kDa. From sequence analysis, CpPLD1 was identified as a PLD belonging to the plant phosphatidylcholine phosphatidohydrolase family.

  18. Role of phospholipase A(2) in retrograde transport of ricin.

    PubMed

    Klokk, Tove Irene; Lingelem, Anne Berit Dyve; Myrann, Anne-Grethe; Sandvig, Kirsten

    2011-09-01

    Ricin is a protein toxin classified as a bioterror agent, for which there are no known treatment options available after intoxication. It is composed of an enzymatically active A-chain connected by a disulfide bond to a cell binding B-chain. After internalization by endocytosis, ricin is transported retrogradely to the Golgi and ER, from where the ricin A-chain is translocated to the cytosol where it inhibits protein synthesis and thus induces cell death. We have identified cytoplasmic phospholipase A(2) (PLA(2)) as an important factor in ricin retrograde transport. Inhibition of PLA(2) protects against ricin challenge, however the toxin can still be endocytosed and transported to the Golgi. Interestingly, ricin transport from the Golgi to the ER is strongly impaired in response to PLA(2) inhibition. Confocal microscopy analysis shows that ricin is still colocalized with the trans-Golgi marker TGN46 in the presence of PLA(2) inhibitor, but less is colocalized with the cis-Golgi marker GM130. We propose that PLA(2) inhibition results in impaired ricin transport through the Golgi stack, thus preventing it from reaching the ER. Consequently, ricin cannot be translocated to the cytosol to exert its toxic action.

  19. Phospholipase Cε Modulates Rap1 Activity and the Endothelial Barrier

    PubMed Central

    DiStefano, Peter V.; Smrcka, Alan V.; Glading, Angela J.

    2016-01-01

    The phosphoinositide-specific phospholipase C, PLCε, is a unique signaling protein with known roles in regulating cardiac myocyte growth, astrocyte inflammatory signaling, and tumor formation. PLCε is also expressed in endothelial cells, however its role in endothelial regulation is not fully established. We show that endothelial cells of multiple origins, including human pulmonary artery (HPAEC), human umbilical vein (HUVEC), and immortalized brain microvascular (hCMEC/D3) endothelial cells, express PLCε. Knockdown of PLCε in arterial endothelial monolayers decreased the effectiveness of the endothelial barrier. Concomitantly, RhoA activity and stress fiber formation were increased. PLCε-deficient arterial endothelial cells also exhibited decreased Rap1-GTP levels, which could be restored by activation of the Rap1 GEF, Epac, to rescue the increase in monolayer leak. Reintroduction of PLCε rescued monolayer leak with both the CDC25 GEF domain and the lipase domain of PLCε required to fully activate Rap1 and to rescue endothelial barrier function. Finally, we demonstrate that the barrier promoting effects PLCε are dependent on Rap1 signaling through the Rap1 effector, KRIT1, which we have previously shown is vital for maintaining endothelial barrier stability. Thus we have described a novel role for PLCε PIP2 hydrolytic and Rap GEF activities in arterial endothelial cells, where PLCε-dependent activation of Rap1/KRIT1 signaling promotes endothelial barrier stability. PMID:27612188

  20. Phospholipase Cε Modulates Rap1 Activity and the Endothelial Barrier.

    PubMed

    DiStefano, Peter V; Smrcka, Alan V; Glading, Angela J

    2016-01-01

    The phosphoinositide-specific phospholipase C, PLCε, is a unique signaling protein with known roles in regulating cardiac myocyte growth, astrocyte inflammatory signaling, and tumor formation. PLCε is also expressed in endothelial cells, however its role in endothelial regulation is not fully established. We show that endothelial cells of multiple origins, including human pulmonary artery (HPAEC), human umbilical vein (HUVEC), and immortalized brain microvascular (hCMEC/D3) endothelial cells, express PLCε. Knockdown of PLCε in arterial endothelial monolayers decreased the effectiveness of the endothelial barrier. Concomitantly, RhoA activity and stress fiber formation were increased. PLCε-deficient arterial endothelial cells also exhibited decreased Rap1-GTP levels, which could be restored by activation of the Rap1 GEF, Epac, to rescue the increase in monolayer leak. Reintroduction of PLCε rescued monolayer leak with both the CDC25 GEF domain and the lipase domain of PLCε required to fully activate Rap1 and to rescue endothelial barrier function. Finally, we demonstrate that the barrier promoting effects PLCε are dependent on Rap1 signaling through the Rap1 effector, KRIT1, which we have previously shown is vital for maintaining endothelial barrier stability. Thus we have described a novel role for PLCε PIP2 hydrolytic and Rap GEF activities in arterial endothelial cells, where PLCε-dependent activation of Rap1/KRIT1 signaling promotes endothelial barrier stability.

  1. Pyrimidinoceptor-mediated activation of phospholipase C and phospholipase A2 in RAW 264.7 macrophages.

    PubMed Central

    Lin, W. W.; Lee, Y. T.

    1996-01-01

    1. As well as the presence of P2Z purinoceptors previously found in macrophages, we identified pyrimidinoceptors in RAW 264.7 cells, which activate phospholipase C (PLC) and phospholipase A2 (PLA2). 2. The relative potency of agonists to stimulate inositol phosphate (IP) formation and arachidonic acid (AA) release was UTP = UDP > > ATP, ATP gamma S, 2MeSATP. For both signalling pathways, the EC50 values for UTP and UDP (3 microM) were significantly lower than that for ATP and all other analogues tested (> 100 microM). 3. UTP and UDP displayed no additivity in terms of IP formation and AA release at maximally effective concentrations. 4. UTP-, but not ATP-, evoked AA release was 60% inhibited by pertussis toxin (PTX), while stimulation of IP formation by both agonists was unaffected. Short-term treatment with phorbol 12-myristate 13-acetate (PMA) led to a dose-dependent inhibition of IP responses to UTP and UDP, but failed to affect the AA responses. Removal of extracellular Ca2+ inhibited the PI response to UTP, but abolished its AA response. 5. ATP-induction of these two transmembrane signal pathways was decreased in high Mg(2+)-containing medium but potentiated by the removal of extracellular Mg2+. 6. Suramin and reactive blue displayed equal potency to inhibit the IP responses of UTP and ATP. 7. Both UTP and UDP (0.1-100 microM) induced a sustained increase in [Ca2+]i which lasted for more than 10 min. 8. Taken together, these results indicate that in mouse RAW 264.7 macrophages, pyrimidinoceptors with specificity for UTP and UDP mediate the activation of PLC and cytosolic (c) PLA2. The activation of PLC is via a PTX-insensitive G protein, whereas that of cPLA2 is via a PTX-sensitive G protein-dependent pathway. The sustained Ca2+ influx caused by UTP contributes to the activation of cPLA2. RAW 264.7 cells also possess P2z purinoceptors which mediate ATP(4-)-induced PLC and PLA2 activation. Images Figure 3 PMID:8886407

  2. Proteomic insight into reduced cell elongation resulting from overexpression of patatin-related phospholipase pPLAIIIδ in Arabidopsis thaliana

    PubMed Central

    Zheng, Yong; Li, Maoyin; Wang, Xuemin

    2014-01-01

    Patatin-containing phospholipase A (pPLA) hydrolyzes membrane glycerolipids, producing free fatty acids and lysoglycerolipids. Ten pPLAs in the Arabidopsis thaliana genome are grouped into 3 subfamilies, and pPLAIIIs differ from pPLAI and IIs in their catalytic motifs and overexpression (OE) of pPLAIIIs reduces cell elongation and cellulose content. To probe the question of how pPLAIII overexpression results in the changes, comparative proteomic analyses were conducted between pPLAIIIδ-OE and WT seedlings. The data indicate a change in the microtubule-associated protein, MAP18. MAP18 is involved in destabilizing cortical microtubules and modulating directional cell growth. The result suggests that pPLAIII and their derived products may regulate cytoskeletal dynamics leading to retardation in anisotropic growth. PMID:24705037

  3. dBASE IV basics

    SciTech Connect

    O`Connor, P.

    1994-09-01

    This is a user`s manual for dBASE IV. dBASE IV is a popular software application that can be used on your personal computer to help organize and maintain your database files. It is actually a set of tools with which you can create, organize, select and manipulate data in a simple yet effective manner. dBASE IV offers three methods of working with the product: (1) control center: (2) command line; and (3) programming.

  4. Recombinant Phospholipase A1 of the Outer Membrane of Psychrotrophic Yersinia pseudotuberculosis: Expression, Purification, and Characterization.

    PubMed

    Bakholdina, S I; Tischenko, N M; Sidorin, E V; Isaeva, M P; Likhatskaya, G N; Dmitrenok, P S; Kim, N Yu; Chernikov, O V; Solov'eva, T F

    2016-01-01

    The pldA gene encoding membrane-bound phospholipase A1 of Yersinia pseudotuberculosis was cloned and expressed in Escherichia coli cells. Recombinant phospholipase A1 (rPldA) was isolated from inclusion bodies dissolved in 8 M urea by two-stage chromatography (ion-exchange and gel-filtration chromatography) as an inactive monomer. The molecular mass of the rPldA determined by MALDI-TOF MS was 31.7 ± 0.4 kDa. The highly purified rPldA was refolded by 10-fold dilution with buffer containing 10 mM Triton X-100 and subsequent incubation at room temperature for 16 h. The refolded rPldA hydrolyzed 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine in the presence of calcium ions. The enzyme exhibited maximal activity at 37°C and nearly 40% of maximal activity at 15°C. The phospholipase A1 was active over a wide range of pH from 4 to 11, exhibiting maximal activity at pH 10. Spatial structure models of the monomer and the dimer of Y. pseudotuberculosis phospholipase A1 were constructed, and functionally important amino acid residues of the enzyme were determined. Structural differences between phospholipases A1 from Y. pseudotuberculosis and E. coli, which can affect the functional activity of the enzyme, were revealed.

  5. Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation

    NASA Technical Reports Server (NTRS)

    Vandenburgh, H. H.; Shansky, J.; Karlisch, P.; Solerssi, R. L.

    1993-01-01

    Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins (PG) E2 and F2 alpha which regulate protein turnover rates and muscle cell growth. These stretch-induced PG increases are reduced in low extracellular calcium medium and by specific phospholipase inhibitors. Mechanical stimulation increases the breakdown rate of 3H-arachidonic acid labelled phospholipids, releasing free 3H-arachidonic acid, the rate-limiting precursor of PG synthesis. Mechanical stimulation also increases 3H-arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo-[2-3H]inositol labelled phospholipids. Phospholipase A2 (PLA2), phosphatidylinositol-specific phospholipase C (PLC), and phospholipase D (PLD) are all activated by stretch. The stretch-induced increases in PG production, 3H-arachidonic acid labelled phospholipid breakdown, and 3H-arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitive) whereas the formation of inositol phosphates from myo-[2-3H]inositol labelled phospholipids is dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid-related second messengers arachidonic acid, diacylglycerol, and PG through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol-specific PLC.

  6. Salicylic acid modulates levels of phosphoinositide dependent-phospholipase C substrates and products to remodel the Arabidopsis suspension cell transcriptome

    PubMed Central

    Ruelland, Eric; Pokotylo, Igor; Djafi, Nabila; Cantrel, Catherine; Repellin, Anne; Zachowski, Alain

    2014-01-01

    Basal phosphoinositide-dependent phospholipase C (PI-PLC) activity controls gene expression in Arabidopsis suspension cells and seedlings. PI-PLC catalyzes the production of phosphorylated inositol and diacylglycerol (DAG) from phosphoinositides. It is not known how PI-PLC regulates the transcriptome although the action of DAG-kinase (DGK) on DAG immediately downstream from PI-PLC is responsible for some of the regulation. We previously established a list of genes whose expression is affected in the presence of PI-PLC inhibitors. Here this list of genes was used as a signature in similarity searches of curated plant hormone response transcriptome data. The strongest correlations obtained with the inhibited PI-PLC signature were with salicylic acid (SA) treatments. We confirm here that in Arabidopsis suspension cells SA treatment leads to an increase in phosphoinositides, then demonstrate that SA leads to a significant 20% decrease in phosphatidic acid, indicative of a decrease in PI-PLC products. Previous sets of microarray data were re-assessed. The SA response of one set of genes was dependent on phosphoinositides. Alterations in the levels of a second set of genes, mostly SA-repressed genes, could be related to decreases in PI-PLC products that occur in response to SA action. Together, the two groups of genes comprise at least 40% of all SA-responsive genes. Overall these two groups of genes are distinct in the functional categories of the proteins they encode, their promoter cis-elements and their regulation by DGK or phospholipase D. SA-regulated genes dependent on phosphoinositides are typical SA response genes while those with an SA response that is possibly dependent on PI-PLC products are less SA-specific. We propose a model in which SA inhibits PI-PLC activity and alters levels of PI-PLC products and substrates, thereby regulating gene expression divergently. PMID:25426125

  7. A Randomized Phase III Trial of IV Carboplatin and Paclitaxel x 3 Courses Followed by Observation Versus Weekly Maintenance Low Dose Paclitaxel in Patients with Early Stage Ovarian Carcinoma: a Gynecologic Oncology Group Study

    PubMed Central

    Mannel, Robert S; Brady, Mark F; Kohn, Elise C.; Hanjani, Parviz; Hiura, Masamichi; Lee, Roger; DeGeest, Koen; Cohn, David E; Monk, Bradley J.; Michael, Helen

    2011-01-01

    Purpose To compare the recurrence-free interval (RFI), and safety profile in patients with completely resected high-risk early-stage ovarian cancer patients treated with intravenous (IV) carboplatin and paclitaxel with or without maintenance low-dose paclitaxel for 24 weeks. Methods Eligibility was limited to patients with Stage I-A/B (Grade 3 or clear cell), all I-C or II epithelial ovarian cancer. All patients were to receive carboplatin AUC 6 and paclitaxel 175 mg/m2 q 3 wks × 3 courses with random assignment to either observation or maintenance paclitaxel 40 mg/m2/wk × 24 wks. Recurrence required clinical or radiological evidence of new tumor. Results There were 571 patients enrolled onto this study, of whom 29 were deemed ineligible due to inappropriate stage or pathology, leaving 542 patients. At least 3 cycles of treatment were administered to 524/542 (97%) of patients, and among those assigned to maintenance paclitaxel, 80% completed the regimen. The incidence of grade 2 or worse peripheral neuropathy (15.5% vs 6%), infection/fever (19.9% vs 8.7%), and dermatologic events (70.8% vs 52.1%) were higher on the maintenance regimen (p<0.001). The cumulative probability of recurring within 5 years for the maintenance paclitaxel regimen is 20% vs. 23% for surveillance (hazard ratio 0.807; 95% CI: 0.565–1.15). The probability of surviving 5 years was 85.4% and 86.2%, respectively. Conclusion Maintenance paclitaxel at 40 mg/m2/wk × 24 wks added to standard dose AUC6 and paclitaxel 175 mg/m2 × 3 doses provides no significant increase in RFI. PMID:21529904

  8. Confirmatory Factor Analysis of the WAIS-IV/WMS-IV

    ERIC Educational Resources Information Center

    Holdnack, James A.; Zhou, Xiaobin; Larrabee, Glenn J.; Millis, Scott R.; Salthouse, Timothy A.

    2011-01-01

    The Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV) and the Wechsler Memory Scale-fourth edition (WMS-IV) were co-developed to be used individually or as a combined battery of tests. The independent factor structure of each of the tests has been identified; however, the combined factor structure has yet to be determined. Confirmatory…

  9. Improving IV-A/IV-D Interface. Trainer Guide.

    ERIC Educational Resources Information Center

    National Inst. for Child Support Enforcement, Chevy Chase, MD.

    Effective interface between the Aid to Families with Dependent Children (IV-A) and the Child Support Enforcement (IV-D) programs is a key factor in assisting families in becoming self-sufficient, reducing welfare expenditures, and enforcing parental responsibility to support their children. Consequently, overcoming the procedural, technological,…

  10. Improving IV-A/IV-D Interface. Handbook.

    ERIC Educational Resources Information Center

    National Inst. for Child Support Enforcement, Chevy Chase, MD.

    Effective interface between the Aid to Families with Dependent Children (IV-A) and the Child Support Enforcement (IV-D) programs is a key factor in assisting families in becoming self-sufficient, reducing welfare expenditures, and enforcing parental responsibility to support their children. Consequently, overcoming the procedural, technological,…

  11. 1-Butanol interferes with phospholipase D1 and protein kinase Calpha association and inhibits phospholipase D1 basal activity.

    PubMed

    Hu, Tianhui; Exton, John H

    2005-02-25

    1-Butanol is commonly used as a substrate for phospholipase D (PLD) activity measurement. Surprisingly we found that, in the presence of 30 mM 1-butanol (standard PLD assay conditions), PLD1 activity in COS-7 cells was lost after incubation for 2 min. In contrast, in the presence of the protein kinase C (PKC) inhibitor staurosporine or dominant negative PKCalpha D481E, the activity was sustained for at least 30min. The binding between PLD1 and PKCalpha was also lost after 2 min incubation with 30 mM 1-butanol while staurosporine and D481E maintained the binding. 1-Butanol at 2 mM did not inhibit PLD1 basal activity or PLD1 binding to PKCalpha, and staurosporine and PKCalpha D481E produced a constant increase in PLD1 basal activity of 2-fold. These results indicate that 1-butanol is inhibitory to PLD1 activity by reducing its association with PKCalpha, and that the concentration of 1-butanol is an important consideration in assaying basal PLD1 activity.

  12. In vitro removal of actinide (IV) ions

    DOEpatents

    Weitl, Frederick L.; Raymond, Kenneth N.

    1982-01-01

    A compound of the formula: ##STR1## wherein X is hydrogen or a conventional electron-withdrawing group, particularly --SO.sub.3 H or a salt thereof; n is 2, 3, or 4; m is 2, 3, or 4; and p is 2 or 3. The present compounds are useful as specific sequestering agents for actinide (IV) ions. Also described is a method for the 2,3-dihydroxybenzamidation of azaalkanes.

  13. Forty five years with membrane phospholipids, phospholipases and lipid mediators: A historical perspective.

    PubMed

    Chap, Hugues

    2016-06-01

    Phospholipases play a key role in the metabolism of phospholipids and in cell signaling. They are also a very useful tool to explore phospholipid structure and metabolism as well as membrane organization. They are at the center of this review, covering a period starting in 1971 and focused on a number of subjects in which my colleagues and I have been involved. Those include determination of phospholipid asymmetry in the blood platelet membrane, biosynthesis of lysophosphatidic acid, biochemistry of platelet-activating factor, first attempts to define the role of phosphoinositides in cell signaling, and identification of novel digestive (phospho)lipases such as pancreatic lipase-related protein 2 (PLRP2) or phospholipase B. Besides recalling some of our contributions to those various fields, this review makes an appraisal of the impressive and often unexpected evolution of those various aspects of membrane phospholipids and lipid mediators. It is also the occasion to propose some new working hypotheses.

  14. Vascular smooth muscle cell spreading onto fibrinogen is regulated by calpains and phospholipase C.

    PubMed

    Paulhe, F; Bogyo, A; Chap, H; Perret, B; Racaud-Sultan, C

    2001-11-09

    Fibrinogen deposition and smooth muscle cell migration are important causes of atherosclerosis and angiogenesis. Involvement of calpains in vascular smooth muscle cell adhesion onto fibrinogen was investigated. Using calpain inhibitors, we showed that activation of calpains was required for smooth muscle cell spreading. An increase of (32)P-labeled phosphatidic acid and phosphatidylinositol-3,4-bisphosphate, respective products of phospholipase C and phosphoinositide 3-kinase activities, was measured in adherent cells. Addition of the calpain inhibitor calpeptin strongly decreased phosphatidic acid and phosphatidylinositol-3,4-bisphosphate. However, smooth muscle cell spreading was prevented by the phospholipase C inhibitor U-73122, but poorly modified by phosphoinositide 3-kinase inhibitors wortmannin and LY-294002. Moreover, PLC was found to act upstream of the PI 3-kinase IA isoform. Thus, our data provide the first evidence that calpains are required for smooth muscle cell spreading. Further, phospholipase C activation is pointed as a key step of cell-spreading regulation by calpains.

  15. Sphingosine induces phospholipase D and mitogen activated protein kinase in vascular smooth muscle cells.

    PubMed

    Taher, M M; Abd-Elfattah, A S; Sholley, M M

    1998-12-01

    The enzymes phospholipase D and diacylglycerol kinase generate phosphatidic acid which is considered to be a mitogen. Here we report that sphingosine produced a significant amount of phosphatidic acid in vascular smooth muscle cells from the rat aorta. The diacylglycerol kinase inhibitor R59 949 partially depressed sphingosine induced phosphatidic acid formation, suggesting that activation of phospholipase C and diacylglycerol kinase can not account for the bulk of phosphatidic acid produced and that additional pathways such as phospholipase D may contribute to this. Further, we have shown that phosphatidylethanol was produced by sphingosine when vascular smooth muscle cells were stimulated in the presence of ethanol. Finally, as previously shown for other cell types, sphingosine stimulated mitogen-activated protein kinase in vascular smooth muscle cells.

  16. Interaction of bilirubin with human erythrocyte membranes. Bilirubin binding to neuraminidase- and phospholipase-treated membranes.

    PubMed

    Sato, H; Aono, S; Semba, R; Kashiwamata, S

    1987-11-15

    Saturable bilirubin binding to human erythrocyte membranes was measured before and after digestion with neuraminidase and phospholipases. Neuraminidase-treated erythrocyte membranes did not show any change in their binding properties, indicating that gangliosides could be excluded as candidates for saturable bilirubin-binding sites on erythrocyte membranes. Although bilirubin-binding properties of the membranes did not change after phospholipase D digestion, either, phospholipase C treatment greatly enhanced bilirubin binding. Thus it is suggested that a negatively charged phosphoric acid moiety of phospholipids on the membrane surface may play a role to prevent a large amount of bilirubin from binding to the membranes. Further saturable bilirubin binding to inside-out sealed erythrocyte membrane vesicles showed values comparable with those of the right-side-out sealed membranes, suggesting that the bilirubin-binding sites may be distributed on both outer and inner surfaces of the membranes, or may exist in the membranes where bilirubin may be accessible from either side.

  17. Phospholipase A2 from sheep erythrocyte membranes. Ca2+ dependence and localization.

    PubMed

    Frei, E; Zahler, P

    1979-02-02

    The calcium dependence and the time course of phosphatidylethanolamine and phosphatidylcholine degradation by sheep erythrocyte membrane suspensions in presence of Triton X-100 were investigated. One enzyme with phospholipase A2 specificity was found to be responsible for both phosphatidyl-ethanolamine and phosphatidylcholine degradation. The localization of this enzyme in the membrane of the sheep erythrocyte was investigated by proteolytic treatment of sealed erythrocyte ghosts from the outside and of ghosts which had both sides of the membrane exposed to chymotrypsin. The inability of sealed ghosts to take up chymotrypsin was followed by flux measurements of [14C]dextran carboxyl previously trapped in the ghosts. No efflux of the marker was found during the proteolytic treatment. By comparing the residual phospholipase activities in the membranes from both ghost preparations, we concluded that the phospholipase is oriented to the exterior of the sheep erythrocyte.

  18. NATIONAL COASTAL CONDITION REPORT IV

    EPA Science Inventory

    The National Coastal Condition Report IV (NCCR IV) is the fourth in a series of environmental assessments of U.S. coastal waters and the Great Lakes. The report includes assessments of all the nation’s estuaries in the contiguous 48 states and Puerto Rico, south-eastern Alaska, ...

  19. Enzymatic action of phospholipase A₂ on liposomal drug delivery systems.

    PubMed

    Hansen, Anders H; Mouritsen, Ole G; Arouri, Ahmad

    2015-08-01

    The overexpression of secretory phospholipase A2 (sPLA2) in tumors has opened new avenues for enzyme-triggered active unloading of liposomal antitumor drug carriers selectively at the target tumor. However, the effects of the liposome composition, drug encapsulation, and tumor microenvironment on the activity of sPLA2 are still not well understood. We carried out a physico-chemical study to characterize the sPLA2-assisted breakdown of liposomes using dye-release assays in the context of drug delivery and under physiologically relevant conditions. The influence of temperature, lipid concentration, enzyme concentration, and drug loading on the hydrolysis of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, Tm=42°C) liposomes with snake venom sPLA2 was investigated. The sensitivity of human sPLA2 to the liposome composition was checked using binary lipid mixtures of phosphatidylcholine (PC) and phosphatidylglycerol (PG) phospholipids with C14 and C16 acyl chains. Increasing temperature (36-41°C) was found to mainly shorten the enzyme lag-time, whereas the effect on lipid hydrolysis rate was modest. The enzyme lag-time was also found to be inversely dependent on the lipid-to-enzyme ratio. Drug encapsulation can alter the hydrolysis profile of the carrier liposomes. The activity of human sPLA2 was highly sensitive to the phospholipid acyl-chain length and negative surface charge density of the liposomes. We believe our work will prove useful for the optimization of sPLA2-susceptible liposomal formulations as well as will provide a solid ground for predicting the hydrolysis profile of the liposomes in vivo at the target site.

  20. Variable substrate preference among phospholipase D toxins from sicariid spiders

    SciTech Connect

    Lajoie, Daniel M.; Roberts, Sue A.; Zobel-Thropp, Pamela A.; Delahaye, Jared L.; Bandarian, Vahe; Binford, Greta J.; Cordes, Matthew H. J.

    2015-03-09

    Venoms of the sicariid spiders contain phospholipase D enzyme toxins that can cause severe dermonecrosis and even death in humans. These enzymes convert sphingolipid and lysolipid substrates to cyclic phosphates by activating a hydroxyl nucleophile present in both classes of lipid. The most medically relevant substrates are thought to be sphingomyelin and/or lysophosphatidylcholine. To better understand the substrate preference of these toxins, we used 31P NMR to compare the activity of three related but phylogenetically diverse sicariid toxins against a diverse panel of sphingolipid and lysolipid substrates. Two of the three showed significantly faster turnover of sphingolipids over lysolipids, and all three showed a strong preference for positively charged (choline and/or ethanolamine) over neutral (glycerol and serine) headgroups. Strikingly, however, the enzymes vary widely in their preference for choline, the headgroup of both sphingomyelin and lysophosphatidylcholine, versus ethanolamine. An enzyme from Sicarius terrosus showed a strong preference for ethanolamine over choline, whereas two paralogous enzymes from Loxosceles arizonica either preferred choline or showed no significant preference. Intrigued by the novel substrate preference of the Sicarius enzyme, we solved its crystal structure at 2.1 Å resolution. Lastly, the evolution of variable substrate specificity may help explain the reduced dermonecrotic potential of some natural toxin variants, because mammalian sphingolipids use primarily choline as a positively charged headgroup; it may also be relevant for sicariid predatory behavior, because ethanolamine-containing sphingolipids are common in insect prey.

  1. Generation of choline for acetylcholine synthesis by phospholipase D isoforms

    PubMed Central

    Zhao, Di; Frohman, Michael A; Blusztajn, Jan Krzysztof

    2001-01-01

    Dedication This article is dedicated to the memory of Sue Kim Hanson, a graduate student in the department of Pathology and Laboratory Medicine at Boston University School of Medicine, who perished in the terrorist attacks of September 11, 2001. Abstract Background In cholinergic neurons, the hydrolysis of phosphatidylcholine (PC) by a phospholipase D (PLD)-type enzyme generates some of the precursor choline used for the synthesis of the neurotransmitter acetylcholine (ACh). We sought to determine the molecular identity of the relevant PLD using murine basal forebrain cholinergic SN56 cells in which the expression and activity of the two PLD isoforms, PLD1 and PLD2, were experimentally modified. ACh levels were examined in cells incubated in a choline-free medium, to ensure that their ACh was synthesized entirely from intracellular choline. Results PLD2, but not PLD1, mRNA and protein were detected in these cells and endogenous PLD activity and ACh synthesis were stimulated by phorbol 12-myristate 13-acetate (PMA). Introduction of a PLD2 antisense oligonucleotide into the cells reduced PLD2 mRNA and protein expression by approximately 30%. The PLD2 antisense oligomer similarly reduced basal- and PMA-stimulated PLD activity and ACh levels. Overexpression of mouse PLD2 by transient transfection increased basal- (by 74%) and PMA-stimulated (by 3.2-fold) PLD activity. Moreover, PLD2 transfection increased ACh levels by 26% in the absence of PMA and by 2.1-fold in the presence of PMA. Overexpression of human PLD1 by transient transfection increased PLD activity by 4.6-fold and ACh synthesis by 2.3-fold in the presence of PMA as compared to controls. Conclusions These data identify PLD2 as the endogenous enzyme that hydrolyzes PC to generate choline for ACh synthesis in cholinergic cells, and indicate that in a model system choline generated by PLD1 may also be used for this purpose. PMID:11734063

  2. A novel class of microbial phosphocholine-specific phospholipases C.

    PubMed

    Stonehouse, Martin J; Cota-Gomez, Adela; Parker, Sarah K; Martin, Wesley E; Hankin, Joseph A; Murphy, Robert C; Chen, Weibin; Lim, Kheng B; Hackett, Murray; Vasil, Adriana I; Vasil, Michael L

    2002-11-01

    In this report we describe the 1,500-fold purification and characterization of the haemolytic phospholipase C (PLC) of Pseudomonas aeruginosa, the paradigm member of a novel PLC/phosphatase superfamily. Members include proteins from Mycobacterium tuberculosis, Bordetella spp., Francisella tularensis and Burkholderia pseudomallei. Purification involved overexpression of the plcHR1,2 operon, ion exchange chromatography and native preparative polyacrylamide gel electrophoresis. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry confirmed the presence of two proteins in the purified sample with sizes of 17,117.2 Da (PlcR2) and 78,417 Da (PlcH). Additionally, liquid chromatography electrospray mass spectrometry (LCMS) revealed that PlcH and PlcR2 are at a stoichiometry of 1 : 1. Western blot analysis demonstrated that the enzyme purifies as a heterodimeric complex, PlcHR2. PlcHR2 is only active on choline-containing phospholipids. It is equally active on phosphatidylcholine (PC) and sphingomyelin (SM) and is able to hydrolyse plasmenylcholine phospholipids (plasmalogens). Neither PlcHR2 nor the M. tuberculosis homologues are inhibited by D609 a widely used, competitive inhibitor of the Bacillus cereus PLC. PlcH, PlcR2, and the PlcHR2 complex bind calcium. While calcium has no detectable effect on enzymatic activity, it inhibits the haemolytic activity of PlcHR2. In addition to being required for the secretion of PlcH, the chaperone PlcR2 affects both the enzymatic and haemolytic properties of PlcH. Inclusive in these data is the conclusion that the members of this PC-PLC and phosphatase family possess a novel mechanism for the recognition and hydrolysis of their respective substrates.

  3. Differential roles of phospholipases A2 in neuronal death and neurogenesis: implications for Alzheimer disease.

    PubMed

    Schaeffer, Evelin L; da Silva, Emanuelle R; Novaes, Barbara de A; Skaf, Heni D; Gattaz, Wagner F

    2010-12-01

    The involvement of phospholipase A(2) (PLA(2)) in Alzheimer disease (AD) was first investigated nearly 15 years ago. Over the years, several PLA(2) isoforms have been detected in brain tissue: calcium-dependent secreted PLA(2) or sPLA(2) (IIA, IIC, IIE, V, X, and XII), calcium-dependent cytosolic PLA(2) or cPLA(2) (IVA, IVB, and IVC), and calcium-independent PLA(2) or iPLA(2) (VIA and VIB). Additionally, numerous in vivo and in vitro studies have suggested the role of different brain PLA(2) in both physiological and pathological events. This review aimed to summarize the findings in the literature relating the different brain PLA(2) isoforms with alterations found in AD, such as neuronal cell death and impaired neurogenesis process. The review showed that sPLA(2)-IIA, sPLA(2)-V and cPLA(2)-IVA are involved in neuronal death, whereas sPLA(2)-III and sPLA(2)-X are related to the process of neurogenesis, and that the cPLA(2) and iPLA(2) groups can be involved in both neuronal death and neurogenesis. In AD, there are reports of reduced activity of the cPLA(2) and iPLA(2) groups and increased expression of sPLA(2)-IIA and cPLA(2)-IVA. The findings suggest that the inhibition of cPLA(2) and iPLA(2) isoforms (yet to be determined) might contribute to impaired neurogenesis, whereas stimulation of sPLA(2)-IIA and cPLA(2)-IVA might contribute to neurodegeneration in AD.

  4. Costimulation of AMPA and metabotropic glutamate receptors underlies phospholipase C activation by glutamate in hippocampus.

    PubMed

    Kim, Hye-Hyun; Lee, Kyu-Hee; Lee, Doyun; Han, Young-Eun; Lee, Suk-Ho; Sohn, Jong-Woo; Ho, Won-Kyung

    2015-04-22

    Glutamate, a major neurotransmitter in the brain, activates ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs, respectively). The two types of glutamate receptors interact with each other, as exemplified by the modulation of iGluRs by mGluRs. However, the other way of interaction (i.e., modulation of mGluRs by iGluRs) has not received much attention. In this study, we found that group I mGluR-specific agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) alone is not sufficient to activate phospholipase C (PLC) in rat hippocampus, while glutamate robustly activates PLC. These results suggested that additional mechanisms provided by iGluRs are involved in group I mGluR-mediated PLC activation. A series of experiments demonstrated that glutamate-induced PLC activation is mediated by mGluR5 and is facilitated by local Ca(2+) signals that are induced by AMPA-mediated depolarization and L-type Ca(2+) channel activation. Finally, we found that PLC and L-type Ca(2+) channels are involved in hippocampal mGluR-dependent long-term depression (mGluR-LTD) induced by paired-pulse low-frequency stimulation, but not in DHPG-induced chemical LTD. Together, we propose that AMPA receptors initiate Ca(2+) influx via the L-type Ca(2+) channels that facilitate mGluR5-PLC signaling cascades, which underlie mGluR-LTD in rat hippocampus.

  5. High specificity of human secretory class II phospholipase A2 for phosphatidic acid.

    PubMed

    Snitko, Y; Yoon, E T; Cho, W

    1997-02-01

    Lysophosphatidic acid (LPA) is a potent lipid second messenger which stimulates platelet aggregation, cell proliferation and smooth-muscle contraction. The phospholipase A2 (PLA2)-catalysed hydrolysis of phosphatidic acid (PA) is thought to be a primary synthetic route for LPA. Of the multiple forms of PLA2 present in human tissues, human secretory class-II PLA2 (hs-PLA2) has been implicated in the production of LPA from platelets and whole blood cells challenged with inflammatory stimuli. To explore further the possibility that hs-PLA2 is involved in the production of LPA, we rigorously measured the phospholipid head group specificity of hs-PLA2 by a novel PLA2 kinetic system using polymerized mixed liposomes. Kinetic analysis of recombinant hs-PLA2 demonstrates that hs-PLA2 strongly prefers PA as substrate over other phospholipids found in the mammalian plasma membrane including phosphatidylserine (PS), phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The order of preference is PA > PE approximately PS > PC. To identify amino acid residues of hs-PLA2 that are involved in its unique substrate specificity, we mutated two residues, Glu-56 and Lys-69, which were shown to interact with the phospholipid head group in the X-ray-crystallographic structure of the hs-PLA2-transition-state-analogue complex. The K69Y mutant showed selective inactivation toward PA whereas the E56K mutant displayed a most pronounced inactivation to PE. Thus it appears that Lys-69 is at least partially involved in the PA specificity of hs-PLA2 and Glu-56 in the distinction between PE and PC. In conjunction with a recent cell study [Fourcade, Simon, Viode, Rugani, Leballe, Ragab, Fournie, Sarda and Chap (1995) Cell 80, 919-927], these studies suggest that hs-PLA2 can rapidly hydrolyse PA molecules exposed to the outer layer of cell-derived microvesicles and thereby produce LPA.

  6. An Integrated Safety Assessment Methodology for Generation IV Nuclear Systems

    SciTech Connect

    Timothy J. Leahy

    2010-06-01

    The Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG) was created to develop an effective approach for the safety of Generation IV advanced nuclear energy systems. Early work of the RSWG focused on defining a safety philosophy founded on lessons learned from current and prior generations of nuclear technologies, and on identifying technology characteristics that may help achieve Generation IV safety goals. More recent RSWG work has focused on the definition of an integrated safety assessment methodology for evaluating the safety of Generation IV systems. The methodology, tentatively called ISAM, is an integrated “toolkit” consisting of analytical techniques that are available and matched to appropriate stages of Generation IV system concept development. The integrated methodology is intended to yield safety-related insights that help actively drive the evolving design throughout the technology development cycle, potentially resulting in enhanced safety, reduced costs, and shortened development time.

  7. Lipolytic enzymes in bovine thyroid tissue. I. Subcellular localization, purification and characterization of acid phospholipase A1.

    PubMed

    De Wolf, M; Lagrou, A; Hilderson, H J; Dierick, W

    1978-12-01

    In mammalian cells the catabolism of membrane phosphoglycerides proceeds probably entirely through a deacylation pathway catalysed by phospholipase A and lysophospholipase (Wise & Elwyn, 1965). In the initial attack of diacylphosphoglycerides by phospholipase A two enzymatic activities with different positional specificities have been distinguished: phospholipase A1 (phosphatidate 1-acyl hydrolase EN 3.1.1.32) and phospholipase A2 (phosphatidate 2-acyl hydrolase EN 3.1.1.4) (Van Deenen & De Haas, 1966). Studies on these intracellular phospholipases were mainly concerned with their subcellular localization. Only occasionally more detailed enzymatic investigations have been conducted on them, in contrast to export phospholipases e.g. from snake venom, bee venom and porcine pancreas, which have been extensively investigated (Brockerhoff & Jensen 1974a). In a previous paper (De Wolf et al., 1976a), the presence of phospholipase A1 and phospholipase A2 activities in bovine thyroid was demonstrated, using 1-[9, 10-3H] stearoyl-2-[1-14C] linoleyl-sn-glycero-3-phosphocholine as a substrate. Optimal activity was observed in both instances at pH 4. Addition of the anionic detergent sodium taurocholate increased the A2 type activity and decreased the A1 type activity suggesting the presence of different enzymes. The lack of influence of Ca2+-ions and EDTA and the acid pH optima could suggest lysosomal localization. In this paper the subcellular distribution of both acid phospholipase activities is described as well as a purification scheme for phospholipase A1. Some characteristics of the purified enzyme preparation are discussed.

  8. sPLA2 IB induces human podocyte apoptosis via the M-type phospholipase A2 receptor.

    PubMed

    Pan, Yangbin; Wan, Jianxin; Liu, Yipeng; Yang, Qian; Liang, Wei; Singhal, Pravin C; Saleem, Moin A; Ding, Guohua

    2014-10-22

    The M-type phospholipase A2 receptor (PLA2R) is expressed in podocytes in human glomeruli. Group IB secretory phospholipase A2 (sPLA2 IB), which is one of the ligands of the PLA2R, is more highly expressed in chronic renal failure patients than in controls. However, the roles of the PLA2R and sPLA2 IB in the pathogenesis of glomerular diseases are unknown. In the present study, we found that more podocyte apoptosis occurs in the kidneys of patients with higher PLA2R and serum sPLA2 IB levels. In vitro, we demonstrated that human podocyte cells expressed the PLA2R in the cell membrane. After binding with the PLA2R, sPLA2 IB induced podocyte apoptosis in a time- and concentration-dependent manner. sPLA2 IB-induced podocyte PLA2R upregulation was not only associated with increased ERK1/2 and cPLA2α phosphorylation but also displayed enhanced apoptosis. In contrast, PLA2R-silenced human podocytes displayed attenuated apoptosis. sPLA2 IB enhanced podocyte arachidonic acid (AA) content in a dose-dependent manner. These data indicate that sPLA2 IB has the potential to induce human podocyte apoptosis via binding to the PLA2R. The sPLA2 IB-PLA2R interaction stimulated podocyte apoptosis through activating ERK1/2 and cPLA2α and through increasing the podocyte AA content.

  9. Analysis of the Active-Site Mechanism of Tyrosyl-DNA Phosphodiesterase I: A Member of the Phospholipase D Superfamily

    SciTech Connect

    Gajewski, Stefan; Comeaux, Evan Q.; Jafari, Nauzanene; Bharatham, Nagakumar; Bashford, Donald; White, Stephen W.; van Waardenburg, Robert C.A.M.

    2012-03-15

    Tyrosyl-DNA phosphodiesterase I (Tdp1) is a member of the phospholipase D superfamily that hydrolyzes 3'-phospho-DNA adducts via two conserved catalytic histidines - one acting as the lead nucleophile and the second acting as a general acid/base. Substitution of the second histidine specifically to arginine contributes to the neurodegenerative disease spinocerebellar ataxia with axonal neuropathy (SCAN1). We investigated the catalytic role of this histidine in the yeast protein (His432) using a combination of X-ray crystallography, biochemistry, yeast genetics, and theoretical chemistry. The structures of wild-type Tdp1 and His432Arg both show a phosphorylated form of the nucleophilic histidine that is not observed in the structure of His432Asn. The phosphohistidine is stabilized in the His432Arg structure by the guanidinium group that also restricts the access of nucleophilic water molecule to the Tdp1-DNA intermediate. Biochemical analyses confirm that His432Arg forms an observable and unique Tdp1-DNA adduct during catalysis. Substitution of His432 by Lys does not affect catalytic activity or yeast phenotype, but substitutions with Asn, Gln, Leu, Ala, Ser, and Thr all result in severely compromised enzymes and DNA topoisomerase I-camptothecin dependent lethality. Surprisingly, His432Asn did not show a stable covalent Tdp1-DNA intermediate that suggests another catalytic defect. Theoretical calculations revealed that the defect resides in the nucleophilic histidine and that the pK{sub a} of this histidine is crucially dependent on the second histidine and on the incoming phosphate of the substrate. This represents a unique example of substrate-activated catalysis that applies to the entire phospholipase D superfamily.

  10. PLC/CAMK IV-NF-kappaB involved in the receptor for advanced glycation end products mediated signaling pathway in human endothelial cells.

    PubMed

    You, Jie; Peng, Wei; Lin, Xu; Huang, Qing-Ling; Lin, Jian-Yin

    2010-05-14

    Advanced glycation end products (AGEs) and their interaction with the receptor for advanced glycation end products (RAGE) play an important role in diabetic vascular complications. The current study demonstrated that AGEs significantly increased RAGE expression and the release of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) in human umbilical vein endothelial cell-derived line ECV304 cells. RAGE antisense RNA partially inhibited the expression of TNF-alpha and IL-6 induced by AGEs. Oligonucleotide microarray was used to identify the genes that respond to RAGE activation. Phospholipase C beta 1 (PLC beta 1), phospholipase C beta 4 (PLC beta 4) and calcium/calmodulin-dependent protein kinase IV (CAMK IV) which associated with Ca(2+) signaling were upregulated. The rise of intracellular calcium and the NF-kappaB promoter activity induced by AGEs were suppressed by RAGE antisense RNA, PLC inhibitor U73122 and dominant negative CAMK IV, respectively. These findings suggest that PLC/CAMK IV-NF-kappaB is involved in RAGE mediated signaling pathway in human endothelial cells.

  11. Topological characterisation and identification of critical domains within glucosyltransferase IV (GtrIV) of Shigella flexneri

    PubMed Central

    2011-01-01

    Background The three bacteriophage genes gtrA, gtrB and gtr(type) are responsible for O-antigen glucosylation in Shigella flexneri. Both gtrA and gtrB have been demonstrated to be highly conserved and interchangeable among serotypes while gtr(type) was found to be specific to each serotype, leading to the hypothesis that the Gtr(type) proteins are responsible for attaching glucosyl groups to the O-antigen in a site- and serotype- specific manner. Based on the confirmed topologies of GtrI, GtrII and GtrV, such interaction and attachment of the glucosyl groups to the O-antigen has been postulated to occur in the periplasm. Results In this study, the topology of GtrIV was experimentally determined by creating different fusions between GtrIV and a dual-reporter protein, PhoA/LacZ. This study shows that GtrIV consists of 8 transmembrane helices, 2 large periplasmic loops, 2 small cytoplasmic N- and C- terminal ends and a re-entrant loop that occurs between transmembrane helices III and IV. Though this topology differs from that of GtrI, GtrII, GtrV and GtrX, it is very similar to that of GtrIc. Furthermore, both the N-terminal periplasmic and the C-terminal periplasmic loops are important for GtrIV function as shown via a series of loop deletion experiments and the creation of chimeric proteins between GtrIV and its closest structural homologue, GtrIc. Conclusion The current study provides the basis for elucidating the structure and mechanism of action of this important O-antigen modifying glucosyltransferase. PMID:22188643

  12. Aqueous complexation of thorium(IV), uranium(IV), neptunium(IV), plutonium(III/IV), and cerium(III/IV) with DTPA.

    PubMed

    Brown, M Alex; Paulenova, Alena; Gelis, Artem V

    2012-07-16

    Aqueous complexation of Th(IV), U(IV), Np(IV), Pu(III/IV), and Ce(III/IV) with DTPA was studied by potentiometry, absorption spectrophotometry, and cyclic voltammetry at 1 M ionic strength and 25 °C. The stability constants for the 1:1 complex of each trivalent and tetravalent metal were calculated. From the potentiometric data, we report stability constant values for Ce(III)DTPA, Ce(III)HDTPA, and Th(IV)DTPA of log β(101) = 20.01 ± 0.02, log β(111) = 22.0 ± 0.2, and log β(101) = 29.6 ± 1, respectively. From the absorption spectrophotometry data, we report stability constant values for U(IV)DTPA, Np(IV)DTPA, and Pu(IV)DTPA of log β(101) = 31.8 ± 0.1, 32.3 ± 0.1, and 33.67 ± 0.02, respectively. From the cyclic voltammetry data, we report stability constant values for Ce(IV) and Pu(III) of log β(101) = 34.04 ± 0.04 and 20.58 ± 0.04, respectively. The values obtained in this work are compared and discussed with respect to the ionic radius of each cationic metal.

  13. All-electron molecular Dirac-Hartree-Fock calculations - The group IV tetrahydrides CH4, SiH4, GeH4, SnH4, and PbH4

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.; Taylor, Peter R.; Faegri, Knut, Jr.; Partridge, Harry

    1991-01-01

    A basis-set-expansion Dirac-Hartree-Fock program for molecules is described. Bond lengths and harmonic frequencies are presented for the ground states of the group 4 tetrahydrides, CH4, SiH4, GeH4, SnH4, and PbH4. The results are compared with relativistic effective core potential (RECP) calculations, first-order perturbation theory (PT) calculations and with experimental data. The bond lengths are well predicted by first-order perturbation theory for all molecules, but none of the RECP's considered provides a consistent prediction. Perturbation theory overestimates the relativistic correction to the harmonic frequencies; the RECP calculations underestimate the correction.

  14. Measuring therapeutic response in chronic graft-versus-host disease. National Institutes of Health consensus development project on criteria for clinical trials in chronic graft-versus-host disease: IV. The 2014 Response Criteria Working Group report.

    PubMed

    Lee, Stephanie J; Wolff, Daniel; Kitko, Carrie; Koreth, John; Inamoto, Yoshihiro; Jagasia, Madan; Pidala, Joseph; Olivieri, Attilio; Martin, Paul J; Przepiorka, Donna; Pusic, Iskra; Dignan, Fiona; Mitchell, Sandra A; Lawitschka, Anita; Jacobsohn, David; Hall, Anne M; Flowers, Mary E D; Schultz, Kirk R; Vogelsang, Georgia; Pavletic, Steven

    2015-06-01

    In 2005, the National Institutes of Health (NIH) Chronic Graft-versus-Host Disease (GVHD) Consensus Response Criteria Working Group recommended several measures to document serial evaluations of chronic GVHD organ involvement. Provisional definitions of complete response, partial response, and progression were proposed for each organ and for overall outcome. Based on publications over the last 9 years, the 2014 Working Group has updated its recommendations for measures and interpretation of organ and overall responses. Major changes include elimination of several clinical parameters from the determination of response, updates to or addition of new organ scales to assess response, and the recognition that progression excludes minimal, clinically insignificant worsening that does not usually warrant a change in therapy. The response definitions have been revised to reflect these changes and are expected to enhance reliability and practical utility of these measures in clinical trials. Clarification is provided about response assessment after the addition of topical or organ-targeted treatment. Ancillary measures are strongly encouraged in clinical trials. Areas suggested for additional research include criteria to identify irreversible organ damage and validation of the modified response criteria, including in the pediatric population.

  15. Intestinal alkaline sphingomyelinase hydrolyses and inactivates platelet-activating factor by a phospholipase C activity

    PubMed Central

    Wu, Jun; Nilsson, Åke; Jönsson, Bo A. G.; Stenstad, Hanna; Agace, William; Cheng, Yajun; Duan, Rui-Dong

    2005-01-01

    Alkaline sphingomyelinase (alk-SMase) is a new member of the NPP (nucleotide pyrophosphatase/phosphodiesterase) family that hydrolyses SM (sphingomyelin) to generate ceramide in the intestinal tract. The enzyme may protect the intestinal mucosa from inflammation and tumorigenesis. PAF (platelet-activating factor) is a pro-inflammatory phospholipid involved in pathogenesis of inflammatory bowel diseases. We examined whether alk-SMase can hydrolyse and inactivate PAF. [3H]Octadecyl-labelled PAF was incubated with purified rat intestinal alk-SMase or recombinant human alk-SMase expressed in COS-7 cells. The hydrolytic products were assayed with TLC and MS. We found that alkSMase cleaved the phosphocholine head group from PAF and generated 1-O-alkyl-2-acetyl-sn-glycerol. Differing from the activity against SM, the activity against PAF was optimal at pH 7.5, inhibited by EDTA and stimulated by 0.1–0.25 mM Zn2+. The activity was abolished by site mutation of the predicted metal-binding sites that are conserved in all NPP members. Similar to the activity against SM, the activity against PAF was dependent on bile salt, particularly taurocholate and taurochenodeoxycholate. The Vmax for PAF hydrolysis was 374 μmol·h−1·(mg of protein)−1. The hydrolysis of PAF and SM could be inhibited by the presence of SM and PAF respectively, the inhibition of PAF hydrolysis by SM being stronger. The PAF-induced MAPK (mitogen-activated protein kinase) activation and IL-8 (interleukin 8) release in HT-29 cells, and chemotaxis in leucocytes were abolished by alk-SMase treatment. In conclusion, alk-SMase hydrolyses and inactivates PAF by a phospholipase C activity. The finding reveals a novel function, by which alk-SMase may counteract the development of intestinal inflammation and colon cancer. PMID:16255717

  16. Expression of phospholipase C isozymes by murine B lymphocytes.

    PubMed

    Hempel, W M; DeFranco, A L

    1991-06-01

    Cross-linking of membrane (m) Ig, the B cell receptor for Ag, activates protein tyrosine phosphorylation and hydrolysis of phosphotidylinositol 4,5-bisphosphate. The latter signal transduction pathway is an important mediator of antigen receptor engagement. The initial event in this pathway is the activation of phospholipase C (PLC). The identity of the isozyme of PLC used in B cells and the mechanism by which it becomes activated are currently unknown. The cDNA encoding five different isozymes have been cloned. As a first step in identifying the isozyme of PLC that is coupled to mIgM, murine cDNA fragments for the five cloned PLC isozymes were generated by the polymerase chain reaction (PCR), cloned, and used to screen a panel of B cell lines representing different stages of development for PLC mRNA expression. All the B cell lines tested expressed high levels of PLC alpha and PLC gamma 2 mRNA, whereas PLC beta and PLC delta mRNA expression were undetectable by both Northern blot and PCR analysis. PLC gamma 1 had a more complicated pattern of mRNA expression. PLC gamma 1 mRNA expression was lower than that observed for PLC alpha or PLC gamma 2 mRNA and varied widely among different cell lines. The pattern of PLC gamma 1 mRNA expression did not correlate with the developmental stage of the cell lines. The pattern of PLC gamma 1 protein expression in the panel of B cell lines correlated with the pattern of PLC gamma 1 mRNA expression. PLC gamma 1 expression was very low in several B cell lines, despite the fact that these cell lines show mIgM-stimulatable PLC activity. The variable and in some cases very low expression of PLC gamma 1 suggests that it may not be the form of PLC that is activated by mIgM. In contrast, PLC alpha and PLC gamma 2 were abundantly expressed in all B cell lines tested. This observation is consistent with the possibility that PLC alpha or PLC gamma 2 is activated by mIgM.

  17. Geometry of PDE's. IV

    NASA Astrophysics Data System (ADS)

    Prástaro, Agostino

    2008-02-01

    Following our previous results on this subject [R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(I): Webs on PDE's and integral bordism groups. The general theory, Adv. Math. Sci. Appl. 17 (2007) 239-266; R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(II): Webs on PDE's and integral bordism groups. Applications to Riemannian geometry PDE's, Adv. Math. Sci. Appl. 17 (2007) 267-285; A. Prástaro, Geometry of PDE's and Mechanics, World Scientific, Singapore, 1996; A. Prástaro, Quantum and integral (co)bordism in partial differential equations, Acta Appl. Math. (5) (3) (1998) 243-302; A. Prástaro, (Co)bordism groups in PDE's, Acta Appl. Math. 59 (2) (1999) 111-201; A. Prástaro, Quantized Partial Differential Equations, World Scientific Publishing Co, Singapore, 2004, 500 pp.; A. Prástaro, Geometry of PDE's. I: Integral bordism groups in PDE's, J. Math. Anal. Appl. 319 (2006) 547-566; A. Prástaro, Geometry of PDE's. II: Variational PDE's and integral bordism groups, J. Math. Anal. Appl. 321 (2006) 930-948; A. Prástaro, Th.M. Rassias, Ulam stability in geometry of PDE's, Nonlinear Funct. Anal. Appl. 8 (2) (2003) 259-278; I. Stakgold, Boundary Value Problems of Mathematical Physics, I, The MacMillan Company, New York, 1967; I. Stakgold, Boundary Value Problems of Mathematical Physics, II, Collier-MacMillan, Canada, Ltd, Toronto, Ontario, 1968], integral bordism groups of the Navier-Stokes equation are calculated for smooth, singular and weak solutions, respectively. Then a characterization of global solutions is made on this ground. Enough conditions to assure existence of global smooth solutions are given and related to nullity of integral characteristic numbers of the boundaries. Stability of global solutions are related to some characteristic numbers of the space-like Cauchy dataE Global solutions of variational problems constrained by (NS) are classified by means of suitable integral bordism groups too.

  18. A novel anti-inflammatory role for secretory phospholipase A2 in immune complex-mediated arthritis.

    PubMed

    Boilard, Eric; Lai, Ying; Larabee, Katherine; Balestrieri, Barbara; Ghomashchi, Farideh; Fujioka, Daisuke; Gobezie, Reuben; Coblyn, Jonathan S; Weinblatt, Michael E; Massarotti, Elena M; Thornhill, Thomas S; Divangahi, Maziar; Remold, Heinz; Lambeau, Gérard; Gelb, Michael H; Arm, Jonathan P; Lee, David M

    2010-05-01

    Phospholipase A2 (PLA2) catalyses the release of arachidonic acid for generation of lipid mediators of inflammation and is crucial in diverse inflammatory processes. The functions of the secretory PLA2 enzymes (sPLA2), numbering nine members in humans, are poorly understood, though they have been shown to participate in lipid mediator generation and the associated inflammation. To further understand the roles of sPLA2 in disease, we quantified the expression of these enzymes in the synovial fluid in rheumatoid arthritis and used gene-deleted mice to examine their contribution in a mouse model of autoimmune erosive inflammatory arthritis. Contrary to expectation, we find that the group V sPLA2 isoform plays a novel anti-inflammatory role that opposes the pro-inflammatory activity of group IIA sPLA2. Mechanistically, group V sPLA2 counter-regulation includes promotion of immune complex clearance by regulating cysteinyl leukotriene synthesis. These observations identify a novel anti-inflammatory function for a PLA2 and identify group V sPLA2 as a potential biotherapeutic for treatment of immune-complex-mediated inflammation.

  19. A novel anti-inflammatory role for secretory phospholipase A2 in immune complex-mediated arthritis

    PubMed Central

    Boilard, Eric; Lai, Ying; Larabee, Katherine; Balestrieri, Barbara; Ghomashchi, Farideh; Fujioka, Daisuke; Gobezie, Reuben; Coblyn, Jonathan S; Weinblatt, Michael E; Massarotti, Elena M; Thornhill, Thomas S; Divangahi, Maziar; Remold, Heinz; Lambeau, Gérard; Gelb, Michael H; Arm, Jonathan P; Lee, David M

    2010-01-01

    Phospholipase A2 (PLA2) catalyses the release of arachidonic acid for generation of lipid mediators of inflammation and is crucial in diverse inflammatory processes. The functions of the secretory PLA2 enzymes (sPLA2), numbering nine members in humans, are poorly understood, though they have been shown to participate in lipid mediator generation and the associated inflammation. To further understand the roles of sPLA2 in disease, we quantified the expression of these enzymes in the synovial fluid in rheumatoid arthritis and used gene-deleted mice to examine their contribution in a mouse model of autoimmune erosive inflammatory arthritis. Contrary to expectation, we find that the group V sPLA2 isoform plays a novel anti-inflammatory role that opposes the pro-inflammatory activity of group IIA sPLA2. Mechanistically, group V sPLA2 counter-regulation includes promotion of immune complex clearance by regulating cysteinyl leukotriene synthesis. These observations identify a novel anti-inflammatory function for a PLA2 and identify group V sPLA2 as a potential biotherapeutic for treatment of immune-complex-mediated inflammation. PMID:20432503

  20. A tyrosine kinase regulates alpha-adrenoceptor-stimulated contraction and phospholipase D activation in the rat aorta.

    PubMed

    Jinsi, A; Paradise, J; Deth, R C

    1996-04-29

    Since previous studies had indicated a role for tyrosine kinases in alpha 2-adrenoceptor-induced contractile responses in other blood vessels, as well as in the activation of phospholipase D, we examined the sensitivity of these responses in rat aorta to the tyrosine kinase inhibitor genistein. Contractions induced by both noradrenaline and the alpha 2-adrenoceptor-selective agonist UK14304 (5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline) were fully inhibited by genistein, with the latter responses being more sensitive. Contractions induced by high K+ buffer were also inhibited, but to a lesser extent. Both agonists caused a stimulation of phospholipase D activity, which could be blocked by pretreatment with pertussis toxin, indicating involvement of either Gi or Go. Genistein completely inhibited the agonist-induced phospholipase D activity and also substantially reduced the basal level of phospholipase D activity. Pretreatment with either the alpha 1-adrenoceptor antagonist prazosin or the alpha 2-adrenoceptor antagonist rauwolscine was also effective in eliminating the agonist-induced increase of phospholipase D. These results indicate that a tyrosine kinase-regulated phospholipase D plays a critical role in alpha-adrenoceptor-induced contractions of the rat aorta and that stimulation of both alpha 1- and alpha 2-adrenoceptors is essential to allow phospholipase activation.

  1. Identification of the Elusive Mammalian Enzyme Phospatidylcholine-Specific Phospholipase C

    DTIC Science & Technology

    2015-01-01

    mammalian protein, phosphatidycholine- specific phospholipase C (PC-PLC) in the inflammatory processes involved in progression of rheumatoid arthritis (RA...serum, rheumatoid arthritis , transcriptome sequencing, HUVECs, U937 cells 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF...aims at identifying novel players that are critically involved in the progression of rheumatoid arthritis (RA). The identification of these factors

  2. Activation of phospholipase A/sub 2/ by carbon tetrachloride in isolated rat hepatocytes

    SciTech Connect

    Glende, E.A. Jr.; Pushpendran, C.K.

    1986-03-05

    Freshly isolated rat hepatocytes were incubated with /sup 3/H-arachidonic acid or /sup 14/C-ethanolamine for 1 hour in order to label cellular lipids. Thin-layer chromatographic analysis indicated that of the /sup 3/H-arachidonate incorporated into lipid nearly 50% was found in phosphatidylcholine and 15% in phosphatidylethanolamine. /sup 14/C-Ethanolamine was incorporated mainly into phosphatidylethanolamine. Hepatocytes labeled as such were exposed to carbon tetrachloride (CCl/sub 4/) for periods up to 4 hours. Phospholipase A/sub 2/ of these preparations was determined by measuring either the release of /sup 4/H-arachidonic acid from cellular phospholipids prelabeled with /sup 3/H-arachidonic acid or measuring the formation of /sup 14/C-lysophosphatidylethanolamine from cellular lipids prelabeled with /sup 14/C-ethanolamine. Through the use of hexane-partition extraction and thin-layer chromatographic analysis of hepatocyte lipid extracts it was found that CCl, stimulated phospholipase A/sub 2/ activity in a dose- an time-dependent manner. Carbon tetrachloride at concentrations of 0.23 to 1.3 mM produced a 1.4- to 5.3-fold increase in phospholipase activity which was initiated within 30 to 60 minutes of incubation at 37/sup 0/. A role for phospholipase activation as a secondary mechanism of CCl/sub 4/-induced hepatocyte injury is proposed.

  3. Characteristics and Lethality of a Novel Recombinant Dermonecrotic Venom Phospholipase D from Hemiscorpius lepturus

    PubMed Central

    Torabi, Elham; Behdani, Mahdi; Hosseininejad Chafi, Mohammad; Moazzami, Reza; Sabatier, Jean-Marc; Khalaj, Vahid; Shahbazzadeh, Delavar; Pooshang Bagheri, Kamran

    2017-01-01

    Hemoscorpius lepturus is the most medically important scorpion in Iran. The clinical signs of H. lepturus envenomation are remarkably similar to those reported for brown spiders, including dermonecrosis, hematuria, renal failure and even death. The lethality and toxicity of brown spiders’ venom have been attributed to its phospholipase D activity. This study aims to identify a phospholipase D with possible lethality and dermonecrotic activity in H. lepturus venom. In this study, a cDNA library of the venom glands was generated by Illumina RNA sequencing. Phospholipase D (PLD) from H. lepturus was characterized according to its significant similarity with PLDs from brown spiders. The main chain designated as Hl-RecPLD1 (the first recombinant isoform of H. lepturus PLD) was cloned, expressed and purified. Sphingomyelinase, dermonecrotic and lethal activities were examined. Hl-PLD1 showed remarkable sequence similarity and structural homology with PLDs of brown spiders. The conformation of Hl-PLD1 was predicted as a “TIM beta/alpha-barrel”. The lethal dose 50 (LD50) and dermonecrotic activities of Hl-RecPLD1 were determined as 3.1 µg/mouse and 0.7 cm2 at 1 µg respectively. It is the first report indicating that a similar molecular evolutionary mechanism has occurred in both American brown spiders and this Iranian scorpion. In conclusion, Hl-RecPLD1 is a highly active phospholipase D, which would be considered as the lethal dermonecrotic toxin in H. lepturus venom. PMID:28335389

  4. Relationship between erythrocyte membrane phase properties and susceptibility to secretory phospholipase A2.

    PubMed

    Best, Katrina B; Ohran, Allison J; Hawes, Andrea C; Hazlett, Theodore L; Gratton, Enrico; Judd, Allan M; Bell, John D

    2002-11-26

    Normally, cell membranes resist hydrolysis by secretory phospholipase A(2). However, upon elevation of intracellular calcium, the cells become susceptible. Previous investigations demonstrated a possible relationship between changes in lipid order caused by increased calcium and susceptibility to phospholipase A(2). To further explore this relationship, we used temperature as an experimental means of manipulating membrane physical properties. We then compared the response of human erythrocytes to calcium ionophore at various temperatures in the range of 20-50 degrees C using fluorescence spectroscopy and two-photon fluorescence microscopy. The steady state fluorescence emission of the environment-sensitive probe, laurdan, revealed that erythrocyte membrane order decreases systematically with temperature throughout this range, especially between 28 and 45 degrees C. Furthermore, the ability of calcium ionophore to induce increased membrane order and susceptibility to phospholipase A(2) depended similarly on temperature. Both responses to calcium influx were enhanced as membrane fluidity increased. Analysis of the spatial distribution of laurdan fluorescence at several temperatures indicated that the ordering effect of intracellular calcium on fluid membranes generates an increase in the number of fluid-solid boundaries. Hydrolysis of the membrane appeared to progress outward from these boundaries. We conclude that phospholipase A(2) prefers to hydrolyze lipids in fluid regions of human erythrocyte membranes, but primarily when those regions coexist with domains of ordered lipids.

  5. Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman H.; Shansky, Janet; Karlisch, Patricia; Solerssi, Rosa Lopez

    1991-01-01

    Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins E2 and F2(alpha) which regulate protein turnover rates and muscle cell growth. Mechnical stimulation significantly increases the breakdown rate of (3)H-arachidonic acid labelled phospholipids, releasing free (3)H-arachidonic acid, and the rate-limiting precursor of prostaglandin synthesis. Mechanical stimulation also significantly increases (3)H-arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo-2-(3)H inositol labelled phospholipids. Phospholipase A2, phosphatidylinositol-specific phospholipase C (PLC), and phospholipase D (PLD) are activated by stretch. The lipase inhibitors bromophenacylbromide and RHC80267 together reduce stretch-induced prostaglandin production by 73-83 percent. The stretch-induced increases in prostaglandin production, (3)H-arachidonic acid labelled phospholipid breakdown, and (3)H-arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitive) whereas the formation of inositol phosphates from myo-2-(3)H inositol labelled phospholipids are dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid-related second messengers arachidonic acid, diacylglycerol, and prostaglandins through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol-specific PLC.

  6. Role of polyamines and phospholipase D in maize (Zea mays L.) response to drought stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydroponic experiment was conducted to elucidate the role of polyamines and phospholipase D (PLD) in regulating response of maize plants to drought stress (DS). During the early stage of DS, an increase in PLD activity, independent of polyamines contents, was mainly responsible for stomatal closure...

  7. Phospholipase C Activity in Human Polymorphonuclear Leukocytes: Partial Characterization and Effect of Indomethacin

    DTIC Science & Technology

    1988-12-01

    phospholipase C activity alone, and in the presence of 0.5 mM and I mM indomethacin, is plotted according to Lineweaver and Burke as described previously...The data were plotted according to the method of Lineweaver and Burke (26). The values represent the mean + S.E.M. of values derived from neutrophils of 4 subjects. 18

  8. Ralstonia paucula (Formerly CDC Group IV c-2): Unsuccessful Strain Differentiation with PCR-Based Methods, Study of the 16S-23S Spacer of the rRNA Operon, and Comparison with Other Ralstonia Species (R. eutropha, R. pickettii, R. gilardii, and R. solanacearum)

    PubMed Central

    Moissenet, Didier; Bidet, Philippe; Garbarg-Chenon, Antoine; Arlet, Guillaume; Vu-Thien, Hoang

    2001-01-01

    Ralstonia paucula (formerly CDC group IV c-2) can cause serious human infections. Confronted in 1995 with five cases of nosocomial bacteremia, we found that pulsed-field gel electrophoresis could not distinguish between the isolates and that randomly amplified polymorphic DNA analysis was poorly discriminatory. In this study, we used PCR-ribotyping and PCR-restriction fragment length polymorphism analysis of the spacer 16S-23S ribosomal DNA (rDNA); both methods were unable to differentiate R. paucula isolates. Eighteen strains belonging to other Ralstonia species (one R. eutropha strain, six R. pickettii strains, three R. solanacearum strains, and eight R. gilardii strains) were also tested by PCR-ribotyping, which failed to distinguish between the four species. The 16S-23S rDNA intergenic spacer of R. paucula contains the tRNAIle and tRNAAla genes, which are identical to genes described for R. pickettii and R. solanacearum. PMID:11136807

  9. Ralstonia paucula (Formerly CDC group IV c-2): unsuccessful strain differentiation with PCR-based methods, study of the 16S-23S spacer of the rRNA operon, and comparison with other Ralstonia species (R. eutropha, R. pickettii, R. gilardii, and R. solanacearum).

    PubMed

    Moissenet, D; Bidet, P; Garbarg-Chenon, A; Arlet, G; Vu-Thien, H

    2001-01-01

    Ralstonia paucula (formerly CDC group IV c-2) can cause serious human infections. Confronted in 1995 with five cases of nosocomial bacteremia, we found that pulsed-field gel electrophoresis could not distinguish between the isolates and that randomly amplified polymorphic DNA analysis was poorly discriminatory. In this study, we used PCR-ribotyping and PCR-restriction fragment length polymorphism analysis of the spacer 16S-23S ribosomal DNA (rDNA); both methods were unable to differentiate R. paucula isolates. Eighteen strains belonging to other Ralstonia species (one R. eutropha strain, six R. pickettii strains, three R. solanacearum strains, and eight R. gilardii strains) were also tested by PCR-ribotyping, which failed to distinguish between the four species. The 16S-23S rDNA intergenic spacer of R. paucula contains the tRNA(Ile) and tRNA(Ala) genes, which are identical to genes described for R. pickettii and R. solanacearum.

  10. Akt as a mediator of secretory phospholipase A2 receptor-involved inducible nitric oxide synthase expression.

    PubMed

    Park, Dae-Won; Kim, Jae-Ryong; Kim, Seong-Yong; Sonn, Jong-Kyung; Bang, Ok-Sun; Kang, Shin-Sung; Kim, Jung-Hye; Baek, Suk-Hwan

    2003-02-15

    The induction of inducible NO synthase (iNOS) by group IIA phospholipase A(2) (PLA(2)) involves the stimulation of a novel signaling cascade. In this study, we demonstrate that group IIA PLA(2) up-regulates the expression of iNOS through a novel pathway that includes M-type secretory PLA(2) receptor (sPLA(2)R), phosphatidylinositol 3-kinase (PI3K), and Akt. Group IIA PLA(2) stimulated iNOS expression and promoted nitrite production in a dose- and time-dependent manner in Raw264.7 cells. Upon treating with group IIA PLA(2), Akt is phosphorylated in a PI3K-dependent manner. Pretreatment with LY294002, a PI3K inhibitor, strongly suppressed group IIA PLA(2)-induced iNOS expression and PI3K/Akt activation. The promoter activity of iNOS was stimulated by group IIA PLA(2), and this was suppressed by LY294002. Transfection with Akt cDNA resulted in Akt protein overexpression in Raw264.7 cells and effectively enhanced the group IIA PLA(2)-induced reporter activity of the iNOS promoter. M-type sPLA(2)R was highly expressed in Raw264.7 cells. Overexpression of M-type sPLA(2)R enhanced group IIA PLA(2)-induced promoter activity and iNOS protein expression, and these effects were abolished by LY294002. However, site-directed mutation in residue responsible for PLA(2) catalytic activity markedly reduced their ability to production of nitrites and expression of iNOS. These results suggest that group IIA PLA(2) induces nitrite production by involving of M-type sPLA(2)R, which then mediates signal transduction events that lead to PI3K/Akt activation.

  11. The selective activation of the cardiac sarcolemmal sodium-calcium exchanger by plasmalogenic phosphatidic acid produced by phospholipase D.

    PubMed

    Hale, C C; Ebeling, E G; Hsu, F F; Ford, D A

    1998-01-30

    Since plasmalogens are the predominant phospholipid of cardiac sarcolemma, the activation of the sodium-calcium exchanger by either plasmenylethanolamine or plasmalogenic phosphatidic acid generated by phospholipase D was explored. Sodium-calcium exchange activity was 7-fold greater in proteoliposomes comprised of plasmenylethanolamine compared to proteoliposomes comprised of only plasmenylcholine. Phospholipase D treatment of proteoliposomes resulted in 1 mol % conversion of plasmenylcholine or phosphatidylcholine to their respective phosphatidic acid molecular species with a concomitant 8-fold or 2-fold activation of sodium-calcium exchange activity, respectfully. Thus, phospholipase D-mediated hydrolysis of plasmalogens to phosphatidic acid may be an important mechanism for the regulation of the sodium-calcium exchanger.

  12. In vivo Detection of Phospholipase C by Enzyme-Activated Near-infrared Probes

    PubMed Central

    Mawn, Theresa M.; Popov, Anatoliy V.; Beardsley, Nancy J.; Stefflova, Klara; Milkevitch, Matthew; Zheng, Gang; Delikatny, E. James

    2011-01-01

    In this paper the characterization of the first near-infrared (NIR) phospholipase-activated molecular beacon is reported and its utility for in vivo cancer imaging is demonstrated. The probe consists of three elements: a phospholipid (PL) backbone to which the NIR fluorophore, pyropheophorbide a (Pyro), and the NIR Black Hole Quencher 3 (BHQ) were conjugated. Due to the close proximity of BHQ to Pyro, the Pyro-PtdEtn-BHQ probe is self-quenched until enzyme hydrolysis releases the fluorophore. The Pyro-PtdEtn-BHQ probe is highly specific to one isoform of phospholipase C, phosphatidylcholine-specific phospholipase C (PC-PLC), responsible for catabolizing phosphatidylcholine directly to phosphocholine. Incubation of Pyro-PtdEtn-BHQ in vitro with PC-PLC demonstrated a 150-fold increase in fluorescence that could be inhibited by the specific PC-PLC inhibitor tricyclodecan-9-yl xanthogenate (D609) with an IC50 of 34±8 µM. Since elevations in phosphocholine have been consistently observed by magnetic resonance spectroscopy in a wide array of cancer cells and solid tumors, we assessed the utility of Pyro-PtdEtn-BHQ as a probe for targeted tumor imaging. Injection of Pyro-PtdEtn-BHQ into mice bearing DU145 human prostate tumor xenografts followed by in vivo NIR imaging resulted in a 4-fold increase in tumor radiance over background and a 2 fold increase in the tumor:muscle ratio. Tumor fluorescence enhancement was inhibited with administration of D609. The ability to image PC-PLC activity in vivo provides a unique and sensitive method of monitoring one of the critical phospholipase signaling pathways activated in cancer, as well as the phospholipase activities that are altered in response to cancer treatment. PMID:22034913

  13. [Simplified microdetermination of cerebral phospholipase A1, A2 and lysophopholipase].

    PubMed

    Hirashima, Y; Koshu, K; Kamiyama, K; Endo, S; Takaku, A; Honda, T; Takasaki, C

    1983-08-01

    The purpose of our study was to examine the ischemia induced enzymatic changes of decaylation-reacylation cycle of membrane phospholipids in dog brain. In this study, we developed new modified method for assay of phospholipase A1, A2 and lysophospholipase which is simpler and needs only a smaller amount of materials. For the first report, we introduced this new method and demonstrated some properties of phospholipase A1, A2 and lysophospholipase in dog brain. Crude enzyme solution for assays of phospholipase A1, A2 and lysophospholipase was gained from extraction of frozen brain with aceton, butanol and saline. The level of phosphorus in the enzyme extract was determined and only those extracts which had a level of phosphorus within a certain range were used. The substrates for assays were L-alpha-[beta-palmitoyl-1-14C] phosphatidylcholine, dipalmitoyl for phospholipase A1 and A2 and L-lysophosphatidylcholine-1-[1-14C] palmitoyl for lysophospolipase respectively. Each radioactive substrates was diluted with cold carrier lipid to give the proper specific activity. Reaction system including substrate, buffer [pH 7.0] and enzyme extract was incubated for 10 hours at 38 degrees C. But for the assay of phospholipase A1 and A2, enzyme solution was pre-incubated at 70 degrees C for 5 minutes. In our new method, reaction mixture was directly separated by TLC without extracting lipids. Enzyme activities were calculated from radio thin-layer chromatograms. Furthermore, we made a comparison between our method and the former one. The value of each enzyme activity was slightly higher in our method than in the former one. However, it was revealed that the results were reproducible in both methods.

  14. Mutagenesis of putative catalytic and regulatory residues of Streptomyces chromofuscus phospholipase D differentially modifies phosphatase and phosphodiesterase activities.

    PubMed

    Zambonelli, Carlo; Casali, Monica; Roberts, Mary F

    2003-12-26

    Phospholipase D from Streptomyces chromofuscus (sc-PLD) is a member of the diverse family of metallo-phosphodiesterase/phosphatase enzymes that also includes purple acid phosphatases, protein phosphatases, and nucleotide phosphodiesterases. Whereas iron is an essential cofactor for scPLD activity, Mn2+ is also found in the enzyme. A third metal ion, Ca2+, has been shown to enhance scPLD catalytic activity although it is not an essential cofactor. Sequence alignment of scPLD with known phosphodiesterases and phosphatases requiring metal ions suggested that His-212, Glu-213, and Asp-389 could be involved in Mn2+ binding. H212A, E213A, and D389A were prepared to test this hypothesis. These three mutant enzymes and wild type scPLD show similar metal content but considerably different catalytic properties, suggesting different roles for each residue. His-212 appears involved in binding the phosphate group of substrates, whereas Glu-213 acts as a ligand for Ca2+. D389A showed a greatly reduced phosphodiesterase activity but almost unaltered ability to hydrolyze the phosphate group in p-nitrophenyl phosphate suggesting it had a critical role in aligning groups at the active site to control phosphodiesterase versus phosphatase activities. We propose a model for substrate and cofactor binding to the catalytic site of scPLD based on these results and on sequence alignment to purple acid phosphatases of known structure.

  15. Nanoassemblies containing a fluorouracil/zidovudine glyceryl prodrug with phospholipase A2-triggered drug release for cancer treatment.

    PubMed

    Jin, Yiguang; Yang, Fang; Du, Lina

    2013-12-01

    Secretory phospholipase A2 (sPLA2), which is overexpressed in many tumors, cleaves ester bonds at the sn-2 position of phospholipids. A PLA2-sensitive amphiphilic prodrug, 1-O-octadecyl-2-(5-fluorouracil)-N-acetyl-3-zidovudine-phosphorylglycerol (OFZG), was synthesized and used to prepare nanoassemblies through the injection of a mixture of OFZG/cholesterol/Tween 80 (2:1:0.1, mol:mol:mol) into water. Cholesterol and Tween 80 was incorporated into the OFZG monolayers at the air/water interface to yield nanoassemblies. The resulting nanoassemblies exhibited a narrow size distribution with a mean size of 77.8nm and were stable due to their high surface charges. The in vitro experiments showed that PLA2 degraded OFZG. The nanoassemblies exhibited higher anticancer activity than the parent drug 5-fluorouracil (5-FU) in COLO205, HT-28, and HCT-116 cells. The intravenous (i.v.) administration of the nanoassemblies into mice resulted in the rapid elimination of OFZG from the circulation and its distribution mainly in the liver, lung, spleen, and kidney. After their injection into tumor-bearing mice, the nanoassemblies exhibited anticancer efficiency comparable to that of 5-FU, even though the nanoassemblies contained concentrations of only 1/10 of the molar amount of 5-FU. The lessons learned from the study and methods for the design of PLA2-sensitive amphiphilic prodrugs are also discussed. Enzyme-sensitive amphiphilic combinatorial prodrugs and prodrug-loaded nanoassemblies may represent a new strategy for anticancer drug design.

  16. Incorporation of marine lipids into mitochondrial membranes increases susceptibility to damage by calcium and reactive oxygen species: evidence for enhanced activation of phospholipase A2 in mitochondria enriched with n-3 fatty acids.

    PubMed Central

    Malis, C D; Weber, P C; Leaf, A; Bonventre, J V

    1990-01-01

    Experiments were designed to evaluate the susceptibility of mitochondrial membranes enriched with n-3 fatty acids to damage by Ca2+ and reactive oxygen species. Fatty acid content and respiratory function were assessed in renal cortical mitochondria isolated from fish-oil- and beef-tallow-fed rats. Dietary fish oils were readily incorporated into mitochondrial membranes. After exposure to Ca2+ and reactive oxygen species, mitochondria enriched in n-3 fatty acids, and using pyruvate and malate as substrates, had significantly greater changes in state 3 and uncoupled respirations, when compared with mitochondria from rats fed beef tallow. Mitochondrial site 1 (NADH coenzyme Q reductase) activity was reduced to 45 and 85% of control values in fish-oil- and beef-tallow-fed groups, respectively. Exposure to Ca2+ and reactive oxygen species enhance the release of polyunsaturated fatty acids enriched at the sn-2 position of phospholipids from mitochondria of fish-oil-fed rats when compared with similarly treated mitochondria of beef-tallow-fed rats. This release of fatty acids was partially inhibited by dibucaine, the phospholipase A2 inhibitor, which we have previously shown to protect mitochondria against damage associated with Ca2+ and reactive oxygen species. The results indicate that phospholipase A2 is activated in mitochondria exposed to Ca2+ and reactive oxygen species and is responsible, at least in part, for the impairment of respiratory function. Phospholipase A2 activity and mitochondrial damage are enhanced when mitochondrial membranes are enriched with n-3 fatty acids. PMID:2123344

  17. Confirmatory factor analysis of the WAIS-IV/WMS-IV.

    PubMed

    Holdnack, James A; Xiaobin Zhou; Larrabee, Glenn J; Millis, Scott R; Salthouse, Timothy A

    2011-06-01

    The Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV) and the Wechsler Memory Scale-fourth edition (WMS-IV) were co-developed to be used individually or as a combined battery of tests. The independent factor structure of each of the tests has been identified; however, the combined factor structure has yet to be determined. Confirmatory factor analysis was applied to the WAIS-IV/WMS-IV Adult battery (i.e., age 16-69 years) co-norming sample (n = 900) to test 13 measurement models. The results indicated that two models fit the data equally well. One model is a seven-factor solution without a hierarchical general ability factor: Verbal Comprehension, Perceptual Reasoning, Processing Speed, Auditory Working Memory, Visual Working Memory, Auditory Memory, and Visual Memory. The second model is a five-factor model composed of Verbal Comprehension, Perceptual Reasoning, Processing Speed, Working Memory, and Memory with a hierarchical general ability factor. Interpretative implications for each model are discussed.

  18. Contribution of alpha3(IV)alpha4(IV)alpha5(IV) Collagen IV to the Mechanical Properties of the Glomerular Basement Membrane

    NASA Astrophysics Data System (ADS)

    Gyoneva, Lazarina

    The glomerular basement membrane (GBM) is a vital part of the blood-urine filtration barrier in the kidneys. In healthy GBMs, the main tension-resisting component is alpha3(IV)alpha4(IV)alpha5(IV) type IV collagen, but in some diseases it is replaced by other collagen IV isoforms. As a result, the GBM becomes leaky and disorganized, ultimately resulting in kidney failure. Our goal is to understanding the biomechanical aspects of the alpha3(IV)alpha4(IV)alpha5(IV) chains and how their absence could be responsible for (1) the initial injury to the GBM and (2) progression to kidney failure. A combination of experiments and computational models were designed for that purpose. A model basement membrane was used to compare experimentally the distensibility of tissues with the alpha3(IV)alpha4(IV)alpha5(IV) chains present and missing. The experiments showed basement membranes containing alpha3(IV)alpha4(IV)alpha5(IV) chains were less distensible. It has been postulated that the higher level of lateral cross-linking (supercoiling) in the alpha3(IV)alpha4(IV)alpha5(IV) networks contributes additional strength/stability to basement membranes. In a computational model of supercoiled networks, we found that supercoiling greatly increased the stiffness of collagen IV networks but only minimally decreased the permeability, which is well suited for the needs of the GBM. It is also known that the alpha3(IV)alpha4(IV)alpha5(IV) networks are more protected from enzymatic degradation, and we explored their significance in GBM remodeling. Our simulations showed that the more protected network was needed to prevent the system from entering a dangerous feedback cycle due to autoregulation mechanisms in the kidneys. Overall, the work adds to the evidence of biomechanical differences between the alpha3(IV)alpha4(IV)alpha5(IV) networks and other collagen IV networks, points to supercoiling as the main source of biomechanical differences, discusses the suitability of alpha3(IV)alpha4(IV

  19. Synthesis and antitumor activity of new amphiphilic alkylglycerolipids substituted with a polar head group, 2-(2-trimethylammonioethoxy)ethyl or a congeneric oligo(ethyleneoxy)ethyl group.

    PubMed

    Ukawa, K; Imamiya, E; Yamamoto, H; Aono, T; Kozai, Y; Okutani, T; Nomura, H; Honma, Y; Hozumi, M; Kudo, I

    1989-12-01

    A new series of amphiphilic 1-octadecyl glycerolipids (eleven compounds, 1a-k) were designed and synthesized, in which the 3-phosphocholine portion of platelet-activating factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) was replaced by the 2-(2-trimethylammonioethoxy)ethyl group and congeneric groups having oligo(ethyleneoxy)ethyl bridges of various lengths at position 3, together with modification at position 2 (lower alkyl, acetonyl, acetoacetyl, carboxymethyl and pyrimidin-2-yl groups). These ether lipids, characterized by a nonphosphorus lysoglycerolipid structure, showed potent antitumor activity in vitro (human promyelocytic leukemia cells, HL-60, and human epidermoid carcinoma cells, KB) and in vivo (mouse sarcoma S180 and mouse mammary carcinoma MM46). Maximal in vitro potency was obtained with 1-O-octadecyl-2-O-(2-pyrimidinyl)-3-O-[2-(2-trimethylammonioethoxy )ethyl] glycerol (1g; IC50 values for both HL-60 and KB were 0.32 microgram/ml, indicating a higher activity than alkyl-lysophospholipid, ET18-OMe). Several appropriately 2-substituted 1-octadecylglycerolipids with the 3-[2-(2-trimethylammonioethoxy)ethyl] group (e.g., methyl, 1b; butyl, 1f; 2,2,2-trifluoroethyl, 1j; and acetonyl, 1k) showed a potent life-span-prolonging effect on mice with ascites sarcoma S180 and on those with mammary carcinoma MM46, when administered intraperitoneally at 16.5 and 12.5 mg/kg/d, respectively. Compounds 1b and 1k showed definite tumor growth inhibition against solid sarcoma S180 in mice, whether given p.o. or i.v. at 16.5 mg/kg/d. Studies on the structure-activity relationships indicate that the metabolic stability to phospholipase C or related enzymes is at least partly responsible for the potent antitumor activity of this series of ether lipids.

  20. The MAX IV imaging concept.

    PubMed

    Matěj, Zdeněk; Mokso, Rajmund; Larsson, Krister; Hardion, Vincent; Spruce, Darren

    2017-01-01

    The MAX IV Laboratory is currently the synchrotron X-ray source with the beam of highest brilliance. Four imaging beamlines are in construction or in the project phase. Their common characteristic will be the high acquisition rates of phase-enhanced images. This high data flow will be managed at the local computing cluster jointly with the Swedish National Computing Infrastructure. A common image reconstruction and analysis platform is being designed to offer reliable quantification of the multidimensional images acquired at all the imaging beamlines at MAX IV.

  1. Association between Ala379Val polymorphism of lipoprotein-associated phospholipase A2 and migraine without aura in Iranian population

    PubMed Central

    Haghdoost, Faraidoon; Gharzi, Mahsa; Faez, Farough; Hosseinzadeh, Elinaz; Tajaddini, Mohamadhasan; Rafiei, Laleh; Asgari, Fatemeh; Banihashemi, Mahboobeh; Masjedi, Samaneh Sadat; Zandifar, Alireza; Haghjooy-Javanmard, Shaghayegh

    2016-01-01

    Background: Migraine is a common neurovascular disorder with multifactorial and polygenic inheritance. The aim of this study was to investigate the association of a migraine without aura and Ala379Val polymorphism of lipoprotein-associated phospholipase A2 (Lp-PLA2) gene in the Iranian population. Methods: In this study, 103 migraine patients and 100 healthy controls were enrolled. DNA samples were extracted and the Ala379Val polymorphism of Lp-PLA2 gene was investigated. To assess severity of a headache, patients filled out the headache impact test (HIT-6) and migraine severity (MIGSEV) questionnaires. Results: Allele V had significantly lower frequency in the case group than control subjects [P = 0.001, odds ratio (OR) = 0.25, confidence interval (CI): 0.15-0.40]. The frequency of migraine patients that were a carrier of V allele (V/V and A/V) was statistically significant lower than the control group (P = 0.003, OR = 2.39, CI: 1.35-4.23). There was no significant difference of alleles frequency between three grades of MIGSEV (P = 0.316). Furthermore, total HIT-6 score was not significantly different between different genotypes (P = 0.466). Conclusion: Our results showed that Ala379Val gene polymorphism of LP-PLA2 is associated with lower risk of migraine but not with severity of headaches in an Iranian population. PMID:27326362

  2. The elevated lipoprotein-associated phospholipase A2 activity is associated with the occurrence and recurrence of acute cerebral infarction.

    PubMed

    Wei, Lingli; Ke, Zunyu; Zhao, Yu; Cai, Zhiyou

    2017-03-07

    There is a strong association between lipoprotein-associated phospholipase A2 (Lp-PLA2) levels and atherosclerosis-related diseases. The aim of this study was to investigate the role of Lp-PLA2 in the ischemic stroke and further offer clinical evidence that measuring Lp-PLA2 helps predict the risk of stroke occurrence and recurrence. A total of 328 hospitalized patients were recruited, including 179 cases of acute cerebral infarction (ACI) and 149 non-ACI controls. The serum level of Lp-PLA2 in ACI was significantly higher than non-ACI. The serum level of Lp-PLA2 in the recurrence of ACI was significantly higher than the nonrecurrence. The serum levels of Lp-PLA2 in large-artery atherosclerosis subtype were the highest among the subtypes of the Trial of Org 10172 in Acute Stroke Treatment and non-ACI controls. The level of Lp-PLA2 in large-artery atherosclerosis and the cardioembolism group was statistically significantly higher than that of the control cases. There was no statistically significant difference between the small-vessel occlusion group and the control cases. The present study confirmed that the elevated Lp-PLA2 level can be a risk factor for ischemic stroke in the Chinese population. The serum level of Lp-PLA2 may be a predictive factor for the recurrence of ACI.

  3. Computing Device Applications of Group IV Nanoparticle Spectroscopy

    DTIC Science & Technology

    2013-04-01

    Particularly, electron (or exciton) wavefunctions that circulate on the surface were envisioned, adopting aspects of surface plasmon polaritons (SPP...dependent on interband wavefunction symmetry. Second is the surface plasmon polariton (SPP) scattering lifetime. The SPP lifetime has two components

  4. Infrared spectroscopy and theoretical studies of group IV molecules

    NASA Astrophysics Data System (ADS)

    Gonzalez, Eric

    This research involved the formation of novel molecules, and the first observation of infrared active modes and infrared active combination bands of already discovered molecules. The molecules were produced by the laser evaporation of germanium, germanium-carbon, and carbons rod previously sintered in a new built vacuum furnace. The infrared spectra were taken using Bomem FTIR spectrometer with an interface infrared optics toward the formation chamber. These molecules were theoretically simulated using commercial quantum chemistry suites of programs and homemade codes. The linear GeC5Ge germanium-carbon chain has been detected for the first time through the dual laser evaporation of graphite and germanium, the nu4(sigmau) vibrational fundamental was observed at 2158.0 cm-1. Two new vibrational fundamentals of linear GeC3Ge, nu 4(sigma4 = 735.3 cm-1 and nu6(sigma u) = 580.1 cm-1, have been observed. This is apparently the first observation of germanium isotopic shifts in vibrational spectra. Linear GeC3 has been formed by the dual laser ablation of germanium and carbon rods and by single laser ablation of a sintered germanium-carbon rod, and trapped in Ar matrices. Two vibrational fundamentals of linear GeC 3 nu1(sigma) = 1903.9 cm-1 and nu 2(sigma) = 1279.6 cm-1, have been observed. In the present work there is no spectroscopic evidence of cyclic structures for GeC 3 with either the transannular Ge-C or C-C bond although at the coupled cluster level of theory they are both predicted to be ˜7-9 kcal/mol lower in energy than the linear isomer. This result suggests a need for further theoretical studies of GeC3 to see if the cyclic isomers are indeed more stable than the linear. New combination bands of carbon chains have been observed, (nu 1+nu4) = 3388.8 cm-1 of linear C5 and (nu2+nu7) = 3471.8 cm-1 of linear C9. Since the asymmetric stretching1 modes involved in these absorptions have been measured previously it has been possible to assign the infrared inactive symmetric stretching modes, the nu1(sigmag) mode of linear C5 at 1942 cm-1 and the nu 2(sigmag) mode of linear C9 at 1870 cm -1. The nu1(sigmag) mode of linear C 5 is the last undetected fundamental of this molecule. The nu6(sigmau) weakest asymmetric stretching mode of linear C7 has been detected for the first time and has been assigned at 1100.1 cm-1 in solid Ar. The calculation of the intensities of combination bands presented in this work suggests that the second derivatives computed numerically from the first derivatives are precise enough to predict intensities of combination/difference bands with magnitudes of order ˜5 km/mol. Therefore, computing the fundamentals intensities using the mechanical (up to the quartic term) and electrical (up to the second term) anharmonicity corrections might clarify why the intensity predictions using only the first dipole-moment derivatives with pure harmonic states are so inexact. To my knowledge, the inexactness of the calculated fundamental intensities is attributed to the method used for the calculation of the first derivatives of the dipole-moment rather than including anharmonic terms.

  5. Development of Silicon-Based Group IV Lasers

    DTIC Science & Technology

    2014-05-01

    K.Y. Wu, H. H. Cheng, V . I. Mashanov, A . I. Nikiforov, O. P. Pchelyakov, and X. S. Wu, AIP ADVANCES 1, 042118 (2011). (3) Mid-infrared...electroluminescence from a Ge/Ge0.922Sn0.078/Ge double heterostructure p-i-n diode on a Si substrate, H. H. Tseng, K. Y. Wu, H. Li, V . Mashanov, H. H. Cheng, G...photodiodes with strained active layer on Si wafer, H. H. Tseng, H. Li, V . Mashanov, H. H. Cheng, Guo-En Chang, G. Sun and R. A . Soref, Appl. Phys. Lett. 103

  6. Development of Silicon-Based Group IV Lasers

    DTIC Science & Technology

    2012-08-17

    H. Wu, K.Y. Wu, H. H. Cheng, V . I. Mashanov, A . I. Nikiforov, O. P. Pchelyakov, and X. S. Wu, AIP ADVANCES 1, 042118 (2011). (3) Strain analysis...have a breakthrough on Si-based optical emitter. This report is organized as following sections: ( a ) Material growth (b) P-i-N heterostructure (c...Characterization on the structure (d) Future direction of work (e) Publications ( a ) Material growth On the material growth, different

  7. Lipoprotein-associated phospholipase A2 levels are associated with erectile dysfunction in patients without known coronary artery disease.

    PubMed

    Otunctemur, A; Sahin, S; Ozbek, E; Cekmen, M; İnal, A; Tulubas, F; Dursun, M; Besiroglu, H; Koklu, I

    2015-08-01

    Endothelial dysfunction and microvascular damage play a crucial role in the pathogenesis of erectile dysfunction (ED). Lp-PLA2 is a calcium-independent member of the phospholipase A2 family and hydrolyses oxidised phospholipids on low-density lipoprotein (LDL) particles that plays a pivotal role in ox-LDL-induced endothelial dysfunction. The purpose of the current study was to determine the association between Lp-PLA2 levels and ED in patients without known coronary artery disease (CAD). All patients were evaluated for ED and divided into two groups: 88 patients suffering from ED for >1 year were enrolled as an experimental group and 88 patients without ED were enrolled as a control group in this study. Diagnosis of ED was based on the International Index of Erectile Function Score-5. Levels of Lp-PLA2 were measured in serum by colorimetric assay. The relationship between Lp-PLA2 levels and ED in patients was evaluated statistically. The mean age of patients with ED group was 59.4 ± 11.32 and 55.8 ± 9.67 in the control group. Plasma Lp-PLA2 levels were significantly higher in ED than in the control group (220.3 ± 66.90 and 174.8 ± 58.83 pg ml(-1) , respectively, P < 0.001). The Lp-PLA2 levels were negatively correlated with score of ED (r = -0.482, P < 0.05). In logistic regression analysis, enhanced plasma Lp-PLA2 levels result in approximately 1.2-fold increase in ED [1.22 (1.25-2.76)]. In this study, serum Lp-PLA2 levels were found to be associated with endothelial dysfunction predictive of ED. Serum Lp-PLA2 level appears to be a specific predictor of ED, and it may be used in early prediction of ED in the male population.

  8. [Effect of cimetidine with chemotherapy on stage IV colorectal cancer].

    PubMed

    Yoshimatsu, Kazuhiko; Ishibashi, Keiichiro; Hashimoto, Masahiko; Umehara, Arihiro; Yokomizo, Hajime; Yoshida, Kiyohito; Fujimoto, Takashi; Iwasaki, Kiyo; Ogawa, Kenji

    2003-10-01

    We herein report the result of a prospective study to investigate the efficacy of cimetidine administration in conjunction with chemotherapy for stage IV colorectal cancer. Sixty-two patients treated with Leucovorin/5-fluorouracil therapy were enrolled from 1996 to 2000. Both groups were well matched for pre-treatment characteristics. There was no difference in survival in cur B patients. However, the cimetidine group had significantly prolonged survival in the patients with cur C or non-resectable carcinoma. This study suggests that cimetidine treatment may improve the survival of patients with non-curative surgery for stage IV colorectal cancer.

  9. Group I metabotropic glutamate receptor actions in oriens/alveus interneurons of rat hippocampal CA1 region.

    PubMed

    Gee, Christine E; Lacaille, Jean-Claude

    2004-03-12

    Group I metabotropic glutamate receptors (mGluRs) are important for hippocampal interneuron function. We used whole-cell recording and confocal imaging to characterize group I mGluR actions in CA1 oriens/alveus interneurons in slices. In tetrodotoxin and ionotropic glutamate receptor antagonists, the group I mGluR specific agonist DHPG increased intradendritic Ca(2+) levels and depolarized interneurons, whereas the group II mGluR specific agonist DCG-IV and the group III mGluR specific agonist L-AP4 did not. DHPG-induced depolarizing and Ca(2+) responses were antagonized by the group I mGluR antagonist 4CPG, but only Ca(2+) responses were significantly inhibited by the mGluR1 antagonist CPCCOEt. DHPG-induced depolarizing responses were not blocked by the inositol-1,4,5-trisphosphate (IP(3)) receptor inhibitor heparin, the protein kinase C (PKC) antagonists GF-109203X, or the inhibitor of phospholipase C (PLC) U73122. Thus, these responses to DHPG may not be transduced by the PLC-->IP(3)/diacylglycerol (DAG) pathway classically linked to group I mGluRs. DHPG-induced depolarizations were not blocked by intracellular GDP beta S or bath-application of N-ethylmaleimide (NEM), suggesting the involvement of a G protein-independent pathway. Our findings indicate that group I mGluRs induce a depolarization of oriens/alveus interneurons via a G protein-independent mechanism different from their classic signalling pathway. Since depolarizations are associated with intracellular Ca(2+) rises, these actions may be important for their synaptic plasticity and vulnerability to excitotoxicity.

  10. Intestinal apolipoprotein A-IV gene expression in the piglet.

    PubMed

    Black, D D; Rohwer-Nutter, P L; Davidson, N O

    1990-03-01

    Fetal, newborn, and suckling piglets were used to study the intestinal expression of the apoA-IV gene in the immature mammal. Swine apoA-IV (42 kD) was isolated from fat-fed piglet lipoprotein-deficient plasma by adsorption to Intralipid followed by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electroelution. Rabbit anti-swine apoA-IV antibodies were raised, and apoA-IV was immunoprecipitated from small intestinal homogenates after in vivo radiolabeling with [3H]leucine. ApoA-IV synthesis was expressed as a percentage of total protein synthesis from trichloroacetic acid-precipitable counts. Fetal (40 day gestation) whole small intestine synthesis was 2.1%. Postnatally, 2-day-old newborn piglets given high triglyceride and low triglyceride duodenal infusions, as well as bile diversion, were studied. Synthesis rates in jejunal mucosa in all groups were comparable to the fetal whole intestinal value except in the jejunum of the high-triglyceride group, where synthesis was increased sevenfold. In 1- to 2-week-old fasting, cream-fed, and bile-diverted piglets synthesis was again unchanged except in the fat-fed jejunum, where synthesis doubled. Ileal synthesis rates in newborn and suckling animals were lower than jejunal rates and did not increase with lipid absorption or decrease with bile diversion. Northern blot hybridization of intestinal RNA samples from the newborn groups with an authentic cross-hybridizing human apoA-IV cDNA probe revealed a 1.8 kb signal which was strongest in the high-triglyceride jejunal samples. Slot blot hybridization showed eightfold increased apoA-IV mRNA levels in high-triglyceride jejunal samples as compared to low-triglyceride and bile-diverted jejunum with no differences in beta actin mRNA abundance.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Phospholipase A/sub 2/ stimulation during cell secretion in rat basophilic leukemia cells

    SciTech Connect

    Garcia-Gil, M.; Siraganian, R.P.

    1986-01-01

    The bridging of IgE receptors on rat basophilic leukemia cells (RBL-2H3) results in a number of biochemical events that accompany histamine secretion. Prominent among these is the release of arachidonic acid from cellular phospholipids, which could be due to the activation of phospholipase enzymes. In the present experiments they studied the intracellular activation of phospholipase A/sub 2/ (PLA/sub 2/) during histamine release. The enzyme in the homogenates was capable of cleaving arachidonic acid from different phospholipids. The production of lysophospholipids could play a critical role in histamine release from cells. These results demonstrate the activation of PLA/sub 2/ enzyme in cellular homogenates during the secretory process.

  12. PRMT8 as a phospholipase regulates Purkinje cell dendritic arborization and motor coordination.

    PubMed

    Kim, Jun-Dal; Park, Kyung-Eui; Ishida, Junji; Kako, Koichiro; Hamada, Juri; Kani, Shuichi; Takeuchi, Miki; Namiki, Kana; Fukui, Hajime; Fukuhara, Shigetomo; Hibi, Masahiko; Kobayashi, Makoto; Kanaho, Yasunori; Kasuya, Yoshitoshi; Mochizuki, Naoki; Fukamizu, Akiyoshi

    2015-12-01

    The development of vertebrate neurons requires a change in membrane phosphatidylcholine (PC) metabolism. Although PC hydrolysis is essential for enhanced axonal outgrowth mediated by phospholipase D (PLD), less is known about the determinants of PC metabolism on dendritic arborization. We show that protein arginine methyltransferase 8 (PRMT8) acts as a phospholipase that directly hydrolyzes PC, generating choline and phosphatidic acid. We found that PRMT8 knockout mice (prmt8 (-/-)) displayed abnormal motor behaviors, including hindlimb clasping and hyperactivity. Moreover, prmt8 (-/-) mice and TALEN-induced zebrafish prmt8 mutants and morphants showed abnormal phenotypes, including the development of dendritic trees in Purkinje cells and altered cerebellar structure. Choline and acetylcholine levels were significantly decreased, whereas PC levels were increased, in the cerebellum of prmt8 (-/-) mice. Our findings suggest that PRMT8 acts both as an arginine methyltransferase and as a PC-hydrolyzing PLD that is essential for proper neurological functions.

  13. Identification of the Elusive Mammalian Enzyme Phosphatidylcholine-Specific Phospholipase C

    DTIC Science & Technology

    2014-07-01

    processes involved in progression of rheumatoid arthritis (RA). Thus, the main scopes of this proposal are: 1. to identify the PC-PLC gene and protein...of PC-PLC. 15. SUBJECT TERMS Phosphatidycholine-specific phospholipase C, lipopolisaccharide, oxidized lipoproteins, serum, rheumatoid arthritis ...present proposal aims at identifying novel players that are critically involved in the progression of rheumatoid arthritis (RA). The identification of

  14. Dependence of stimulus-transcription coupling on phospholipase D in agonist-stimulated pituitary cells.

    PubMed Central

    Cesnjaj, M; Zheng, L; Catt, K J; Stojilkovic, S S

    1995-01-01

    Stimulation of phospholipase D activity is frequently observed during agonist activation of Ca(2+)-mobilizing receptors, but the cellular functions of this signaling pathway are not well defined. Pituitary gonadotrophs express Ca(2+)-mobilizing receptors for gonadotropin-releasing hormone (GnRH) and endothelin (ET), activation of which stimulates luteinizing hormone secretion and transient expression of c-fos. In pituitary cells and alpha T3-1 gonadotrophs, GnRH action was associated with both initial and sustained diacylglycerol (DG) production, whereas ET-1 induced only a transient DG response. Also, phospholipase D activity, estimated by the production of phosphatidylethanol from phosphatidylcholine in the presence of ethanol, was stimulated by GnRH but not ET-1. Such formation of phosphatidylethanol at the expense of phosphatidic acid (PA) during GnRH-induced activation of phospholipase D significantly reduced the production of PA, DG, and cytidine diphosphate diacylglycerol. Inhibition of PA-phosphohydrolase activity by propranolol also decreased GnRH-induced DG production and, in contrast to ethanol, increased PA and cytidine diphosphate diacylglycerol levels. The fall in DG production caused by ethanol and propranolol was accompanied by inhibition of GnRH-induced c-fos expression, whereas agonist-induced luteinizing hormone release was not affected. In contrast to their inhibitory actions on GnRH-induced early gene expression, neither ethanol nor propranolol affected ET-1-induced c-fos expression, or GnRH- and ET-1-induced inositol trisphosphate/Ca2+ signaling. These findings demonstrate that phospholipase D participates in stimulus-transcription but not stimulus-secretion coupling, and indicate that DG is the primary signal for this action. Images PMID:7579706

  15. Quantum dot-NBD-liposome luminescent probes for monitoring phospholipase A2 activity.

    PubMed

    Kethineedi, Venkata R; Crivat, Georgeta; Tarr, Matthew A; Rosenzweig, Zeev

    2013-12-01

    In this paper we describe the fabrication and characterization of new liposome encapsulated quantum dot-fluorescence resonance energy transfer (FRET)-based probes for monitoring the enzymatic activity of phospholipase A2. To fabricate the probes, luminescent CdSe/ZnS quantum dots capped with trioctylphosphine oxide (TOPO) ligands were incorporated into the lipid bilayer of unilamellar liposomes with an average diameter of approximately 100 nm. Incorporating TOPO capped quantum dots in liposomes enabled their use in aqueous solution while maintaining their hydrophobicity and excellent photophysical properties. The phospholipid bilayer was labeled with the fluorophore NBD C6-HPC (2-(6-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)hexanoyl-1-hexa decanoyl-sn-glycero-3-phosphocholine). The luminescent quantum dots acted as FRET donors and the NBD dye molecules acted as FRET acceptors. The probe response was based on FRET interactions between the quantum dots and the NBD dye molecules. The NBD dye molecules were cleaved and released to the solution in the presence of the enzyme phospholipase A2. This led to an increase of the luminescence of the quantum dots and to a corresponding decrease in the fluorescence of the NBD molecules, because of a decrease in FRET efficiency between the quantum dots and the NBD dye molecules. Because the quantum dots were not attached covalently to the phospholipids, they did not hinder the enzyme activity as a result of steric effects. The probes were able to detect amounts of phospholipase A2 as low as 0.0075 U mL(-1) and to monitor enzyme activity in real time. The probes were also used to screen phospholipase A2 inhibitors. For example, we found that the inhibition efficiency of MJ33 (1-hexadecyl-3-(trifluoroethyl)-sn-glycero-2-phosphomethanol) was higher than that of OBAA (3-(4-octadecyl)benzoylacrylic acid).

  16. Plasma Lipoprotein-associated Phospholipase A2 in Patients with Metabolic Syndrome and Carotid Atherosclerosis

    PubMed Central

    2011-01-01

    Background Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a recently identified and potentially useful plasma biomarker for cardiovascular and atherosclerotic diseases. However, the correlation between the Lp-PLA2 activity and carotid atherosclerosis remains poorly investigated in patients with metabolic syndrome (MetS). The present study aimed to evaluate the potential role of Lp-PLA2 as a comprehensive marker of metabolic syndrome in individuals with and without carotid atherosclerosis. Methods We documented 118 consecutive patients with MetS and 70 age- and sex-matched healthy subjects served as controls. The patients were further divided into two groups: 39 with carotid plaques and 79 without carotid plaques to elucidate the influence of Lp-PLA2 on carotid atherosclerosis. The plasma Lp-PLA2 activity was measured by using ELISA method and carotid intimal-media thickness (IMT) was performed by ultrasound in all participants. Results Lp-PLA2 activity was significantly increased in MetS subgroups when compared with controls, and was higher in patients with carotid plaques than those without plaques (P < 0.05). Furthermore, we found that significant difference in Lp-PLA2 was obtained between patients with three and four disorders of metabolic syndrome (P < 0.01). Age (β = 0.183, P = 0.029), LDL-cholesterol (β = 0.401, P = 0.000) and waist-hip ratio (β = 0.410, P = 0.000) emerged as significant and independent determinants of Lp-PLA2 activity. Multiple stepwise regression analysis revealed that LDL-cholesterol (β = 0.309, P = 0.000), systolic blood pressure (β = 0.322, P = 0.002) and age (β = 0.235, P = 0.007) significantly correlated with max IMT, and Lp-PLA2 was not an independent predictor for carotid IMT. Conclusions Lp-PLA2 may be a modulating factor for carotid IMT via age and LDL-cholesterol, not independent predictor in the pathophysiological process of carotid atherosclerosis in patients with MetS. PMID:21247435

  17. Correlation between plasma lipoprotein-associated phospholipase A2 and peripheral arterial disease.

    PubMed

    Li, Shuai-Bing; Yang, Fan; Jing, Li; Ma, Juan; Jia, Ya-Dan; Dong, Shao-Ying; Zheng, Wei-Feng; Zhao, Luo-Sha

    2013-05-01

    Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a recently identified and potentially useful plasma biomarker for cardiovascular diseases. However, its role in peripheral arterial disease (PAD) remains unclear. The objective of this study was to assess the independent association of Lp-PLA2 and other inflammatory markers with the reduced ankle-brachial blood pressure index (ABI), a marker of PAD. We performed a cross-sectional study in 982 individuals aged ≥40 years who were recruited from the First Affiliated Hospital of Zhengzhou University. PAD was defined as an ABI <0.9 in at least one leg. The individuals were further divided into two groups, 145 with PAD and 837 without PAD. Following adjustment for traditional cardiovascular risk factors, the odds ratios of PAD when comparing the highest to the lowest quartiles were 3.24 (95% CI, 1.68-3.94) for Lp-PLA2, 2.14 (95% CI, 1.07-3.11) for homocysteine, 1.93 (95% CI, 1.02-4.01) for fibrinogen, 2.26 (95% CI, 1.32-5.74) for apolipoprotein B and 1.3 (95% CI, 0.75-2.49) for high-sensitivity C-reactive protein (hsCRP). When Lp-PLA2 and inflammatory markers were simultaneously included in the full model, the corresponding odds ratios were 1.81 (95% CI, 1.14-3.68) for Lp-PLA2, 1.15 (95% CI, 0.49-2.69) for homocysteine, 1.21 (95% CI, 0.88-5.57) for fibrinogen, 0.98 (95% CI, 0.51-3.85) for apolipoprotein B and 1.23 (95% CI, 1.12-3.51) for hsCRP. Lp-PLA2 levels were significantly and independently associated with PAD following adjustment for other inflammatory markers. These findings reflect the potential role of circulating Lp-PLA2 as a marker of atherosclerosis.

  18. Cold stress affects H(+)-ATPase and phospholipase D activity in Arabidopsis.

    PubMed

    Muzi, Carlo; Camoni, Lorenzo; Visconti, Sabina; Aducci, Patrizia

    2016-11-01

    Low temperature is an environmental stress that greatly influences plant performance and distribution. Plants exposed to cold stress exhibit modifications of plasma membrane physical properties that can affect their functionality. Here it is reported the effect of low temperature exposure of Arabidopsis plants on the activity of phospholipase D and H(+)-ATPase, the master enzyme located at the plasma membrane. The H(+)-ATPase activity was differently affected, depending on the length of cold stress imposed. In particular, an exposure to 4 °C for 6 h determined the strong inhibition of the H(+)-ATPase activity, that correlates with a reduced association with the regulatory 14-3-3 proteins. A longer exposure first caused the full recovery of the enzymatic activity followed by a significant activation, in accordance with both the increased association with 14-3-3 proteins and induction of H(+)-ATPase gene transcription. Different time lengths of cold stress treatment were also shown to strongly stimulate the phospholipase D activity and affect the phosphatidic acid levels of the plasma membranes. Our results suggest a functional correlation between the activity of phospholipase D and H(+)-ATPase mediated by phosphatidic acid release during the cold stress response.

  19. [The state of phospholipase D in solution and its catalytic activity].

    PubMed

    Rakhimov, M M; Mad'iarov, Sh R

    1977-04-01

    Functioning of water-soluble phospholipase D from cotton seeds is studied on two phases contact area (liquid-liquid, liquid-solid substance) and on the surface of mixed lecitine and sodium dodecylsulphate micelles. It is found that water-soluble phospholipase D, which normally has no catalytic activity, is capable to hydrolyse its substrates in the presence of organic solvents, solid adsorbents and sodium dodecylsulphate. The data obtained show that in all the cases studied the activation observed is due to adsorption immobilization of the enzyme. K lambda and K alpha constants are introduced, which are characteristics of immobilyzing ability of agents-matrices for immobilization. Phase transitions, which take place in heterogenous system (enzyme-activator-substrate-water solution), are found to be a necessary condition for the enzyme activation. A hypothesis, that catalytical activity of water-soluble phospholipase D is inherent of the adsorbed enzyme, is discussed on the basis of the data on comparative study of adsorbed and water-soluble enzymes.

  20. Involvement of phospholipases C and D in the defence responses of riboflavin-treated tobacco cells.

    PubMed

    Wang, Lianlian; Zhu, Xiaoping; Liu, Jinwei; Chu, Xiaojing; Jiao, Jiao; Liang, Yuancun

    2013-04-01

    Riboflavin is an activator of defence responses in plants that increases resistance against diseases caused by fungal, oomycete, bacterial and viral pathogens. However, the mechanisms driving defence activation by riboflavin are poorly understood. We investigated the signal transduction pathways of phospholipase C (PLC) and phospholipase D (PLD) in tobacco (Nicotiana tabacum) suspension cells using a pharmacological approach to confirm whether riboflavin-mediated activation of the defence response is dependent on both PLC and PLD. The expression patterns analysed by quantitative reverse transcription-polymerase chain reaction demonstrated that the tobacco PLC and PLD gene families were differentially expressed in riboflavin-treated tobacco cells. PLC and PLD expression accompanied defence responses including the expression of defence response genes (PAL, PR-1a and PR-1b), the production of hydrogen peroxide and the accumulation of the phytoalexin scopoletin in tobacco cells treated with riboflavin. These defence responses were significantly inhibited in the presence of the PLC inhibitor U73122 and the PLD inhibitor 1-butanol; however, inhibitor analogues had no effect. Moreover, treating tobacco cells with phosphatidic acid, a signalling molecule produced by phospholipase catalysis, induced the accumulation of the phytoalexin scopoletin and compensated for the suppressive effects of U73122 and 1-butanol on riboflavin-induced accumulation of the phytoalexin. These results offer pharmacological evidence that PLC and PLD play a role in riboflavin-induced defences of tobacco.

  1. Ceramides increase the activity of the secretory phospholipase A2 and alter its fatty acid specificity.

    PubMed Central

    Koumanov, Kamen S; Momchilova, Albena B; Quinn, Peter J; Wolf, Claude

    2002-01-01

    Modulation of human recombinant secretory type II phospholipase A(2) activity by ceramide and cholesterol was investigated using model glycerophospholipid substrates composed of phosphatidylethanolamine and phosphatidylserine dispersed in aqueous medium. Enzyme activity was monitored by measurement of released fatty acids using capillary GC-MS. Fatty acids from the sn-2 position of the phospholipids were hydrolysed by the enzyme in proportion to the relative abundance of the phospholipid in the substrate. Addition of increasing amounts of ceramide to the substrate progressively enhanced phospholipase activity. The increased activity was accomplished largely by preferential hydrolysis of polyunsaturated fatty acids, particularly arachidonic acid, derived from phosphatidylethanolamine. The addition of sphingomyelin to the substrate glycerophospholipids inhibited phospholipase activity but its progressive substitution by ceramide, so as to mimic sphingomyelinase activity, counteracted the inhibition. The presence of cholesterol in dispersions of glycerophospholipid-substrate-containing ceramides suppressed activation of the enzyme resulting from the presence of ceramide. The molecular basis of enzyme modulation was investigated by analysis of the phase structure of the dispersed lipid substrate during temperature scans from 46 to 20 degrees C using small-angle synchrotron X-ray diffraction. These studies indicated that intermediate structures created after ceramide-dependent phase separation of hexagonal and lamellar phases represent the most susceptible form of the substrate for enzyme hydrolysis. PMID:11903045

  2. Evaluation of Expression of Lipases and Phospholipases of Malassezia restricta in Patients with Seborrheic Dermatitis

    PubMed Central

    Lee, Yang Won; Lee, Shin Yung; Lee, Younghoon

    2013-01-01

    Background Malassezia species (spp.) are cutaneous opportunistic pathogens and associated with various dermatological diseases including seborrheic dermatitis, dandruff and atopic dermatitis. Almost all Malassezia spp. are obligatorily lipid-dependent, which might be caused by lack of the myristic acid synthesis. Recent genome analysis of M. restricta and M. globosa suggested that the absence of a gene encoding fatty acid synthesis might be compensated by abundant genes encoding hydrolases, which produce fatty acids, and that lipases and phospholipases may play a role in virulence of the fungus. Objective The current study aimed to investigate the contribution of lipases and phospholipases in virulence of the M. restricta as being the most frequently isolated Malassezia spp. from the human skin. Methods Swap samples of two different body sites of at least 18 patients with seborrheic dermatitis were obtained and in vivo expression of lipases and phospholipases of M. restricta was analyzed by the gene specific two-step nested RT-PCR. Results The results of the current study suggest that majority of the patients display expression of lipase RES_0242. Conclusion These data imply a possible role of lipase in the host environment to produce free fatty acids for the fungus. PMID:24003273

  3. Facile Routes to Th(IV), U(IV), and Np(IV) Phosphites and Phosphates

    SciTech Connect

    Villa, Eric M.; Wang, Shuao; Alekseev, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.

    2011-08-05

    Three actinide(IV) phosphites and a NpIV phosphate, AnIV(HPO₃)₂(H₂O)₂ (An = Th, U, Np) and Cs[Np(H1.5PO₄)(PO₄)]₂, respectively, were synthesized using mild hydrothermal conditions. The first three phases are isotypic and were obtained using similar reaction conditions. Cs[Np(H1.5PO₄)(PO₄)]₂ was synthesized using an analogous method to that of Np(HPO₃)₂(H₂O)₂. However, this fourth phase is quite different in comparison to the other phases in both composition and structure. The structure of Cs[Np(H1.5PO₄)(PO₄)]₂ is constructed from double layers of neptunium(IV) phosphate with caesium cations in the interlayer region. In contrast, An(HPO₃)₂(H₂O)₂ (An = Th, U, Np) form dense 3D networks. The actinide contraction is detected in variety of metrics obtained from single-crystal X-ray diffraction data. Changes in the oxidation state of the neptunium starting materials yield different products.

  4. Lipoprotein-associated phospholipase A2 is associated with postpartum hypertension in women with history of preeclampsia.

    PubMed

    Zhou, Yuheng; Niu, Jianmin; Duan, Dongmei; Lei, Qiong; Wen, Jiying; Lin, Xiaohong; Lv, Lijuan; Chen, Longding

    2015-07-01

    Both hypertension and preeclampsia (PE) are considered as inflammatory diseases. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory marker associated with lipid metabolism. We aimed to study the correlation and predictive value of Lp-PLA2 in postpartum hypertension after PE. A group of 160 PE patients (PE group) and a separate group of 160 normal pregnant women (control group) were recruited from January 2010 to October 2011. The average age in the PE group was 28.4 ± 4.5 years and the average gestational age was 34.7 ± 1.1 weeks. The average age in the control group was 27.8 ± 4.5 years and the average gestational age was 35.5 ± 1.2 weeks. General information (including age, gestational age, parity, history of metabolic disease, family history of high blood pressure, height, body weight before childbirth, and blood pressure) and blood samples were collected for measuring Lp-PLA2 and lipid parameters. From February to April in 2013, 153 cases in the PE group and 132 in the control group were re-called. We assessed their postpartum health, pregnancy, height, weight, and blood pressure. Serum mass of Lp-PLA2 in the PE group (210.67 ± 17.98 ng/mL) was significantly higher compared with that in the control group (174.72 ± 30.26 ng/mL) (P < 0.01). The pro-gestation BMI, systolic blood pressure (SBP), diastolic blood pressure, total cholesterol, triglyceride, and low-density lipoprotein-cholesterol (LDL-C) were also significantly higher. Correlation analysis showed that the level of Lp-PLA2 and SBP (r = 0.31), LDL-C (r = 0.37) were positively correlated. The incidence of postpartum hypertension in the PE group was higher than that in the normal control group. Logistic regression analysis showed that prenatal Lp-PLA2 mass was an independent risk factor for PE postpartum hypertension (OR 1.134,95 % CI 1.086-1.185). ROC curve analysis showed that the sensitivity of predicting postpartum hypertension was 73.2% and the specific degree was 86.6%, with

  5. Patatin-related phospholipase A, pPLAIIIα, modulates the longitudinal growth of vegetative tissues and seeds in rice.

    PubMed

    Liu, Guangmeng; Zhang, Ke; Ai, Jun; Deng, Xianjun; Hong, Yueyun; Wang, Xuemin

    2015-11-01

    Patatin-related phospholipase A (pPLA) hydrolyses glycerolipids to produce fatty acids and lysoglycerolipids. The Oryza sativa genome has 21 putative pPLAs that are grouped into five subfamilies. Overexpression of OspPLAIIIα resulted in a dwarf phenotype with decreased length of rice stems, roots, leaves, seeds, panicles, and seeds, whereas OspPLAIIIα-knockout plants had longer panicles and seeds. OspPLAIIIα-overexpressing plants were less sensitive than wild-type and knockout plants to gibberellin-promoted seedling elongation. OspPLAIIIα overexpression and knockout had an opposite effect on the expression of the growth repressor SLENDER1 in the gibberellin signalling process. OspPLAIIIα-overexpressing plants had decreased mechanical strength and cellulose content, but exhibited increases in the expression of several cellulose synthase genes. These results indicate that OspPLAIIIα plays a role in rice vegetative and reproductive growth and that the constitutive, high activity of OspPLAIIIα suppresses cell elongation. The decreased gibberellin response in overexpressing plants is probably a result of the decreased ability to make cellulose for anisotropic cell expansion.

  6. Study of the Role of Cytosolic Phospholipase A2 Alpha in Eicosanoid Generation and Thymocyte Maturation in the Thymus

    PubMed Central

    Rousseau, Matthieu; Naika, Gajendra S.; Perron, Jean; Jacques, Frederic; Gelb, Michael H.; Boilard, Eric

    2015-01-01

    The thymus is a primary lymphoid organ, home of maturation and selection of thymocytes for generation of functional T-cells. Multiple factors are involved throughout the different stages of the maturation process to tightly regulate T-cell production. The metabolism of arachidonic acid by cyclooxygenases, lipoxygenases and specific isomerases generates eicosanoids, lipid mediators capable of triggering cellular responses. In this study, we determined the profile of expression of the eicosanoids present in the mouse thymus at different stages of thymocyte development. As the group IVA cytosolic phospholipase A2 (cPLA2α) catalyzes the hydrolysis of phospholipids, thereby generating arachidonic acid, we further verified its contribution by including cPLA2α deficient mice to our investigations. We found that a vast array of eicosanoids is expressed in the thymus, which expression is substantially modulated through thymocyte development. The cPLA2α was dispensable in the generation of most eicosanoids in the thymus and consistently, the ablation of the cPLA2α gene in mouse thymus and the culture of thymuses from human newborns in presence of the cPLA2α inhibitor pyrrophenone did not impact thymocyte maturation. This study provides information on the eicosanoid repertoire present during thymocyte development and suggests that thymocyte maturation can occur independently of cPLA2α. PMID:25969996

  7. Study of the role of cytosolic phospholipase A2 alpha in eicosanoid generation and thymocyte maturation in the thymus.

    PubMed

    Rousseau, Matthieu; Naika, Gajendra S; Perron, Jean; Jacques, Frederic; Gelb, Michael H; Boilard, Eric

    2015-01-01

    The thymus is a primary lymphoid organ, home of maturation and selection of thymocytes for generation of functional T-cells. Multiple factors are involved throughout the different stages of the maturation process to tightly regulate T-cell production. The metabolism of arachidonic acid by cyclooxygenases, lipoxygenases and specific isomerases generates eicosanoids, lipid mediators capable of triggering cellular responses. In this study, we determined the profile of expression of the eicosanoids present in the mouse thymus at different stages of thymocyte development. As the group IVA cytosolic phospholipase A2 (cPLA2α) catalyzes the hydrolysis of phospholipids, thereby generating arachidonic acid, we further verified its contribution by including cPLA2α deficient mice to our investigations. We found that a vast array of eicosanoids is expressed in the thymus, which expression is substantially modulated through thymocyte development. The cPLA2α was dispensable in the generation of most eicosanoids in the thymus and consistently, the ablation of the cPLA2α gene in mouse thymus and the culture of thymuses from human newborns in presence of the cPLA2α inhibitor pyrrophenone did not impact thymocyte maturation. This study provides information on the eicosanoid repertoire present during thymocyte development and suggests that thymocyte maturation can occur independently of cPLA2α.

  8. Studies on the endogenous phospholipids of chick embryo myocardium and their in vitro hydrolysis by endogenous phospholipases during embryogenesis.

    PubMed

    Helmy, Fatma M; Aikins, Anthea; Hughes, Jeniter; Belfield, Carrie; Juracka, Amal

    2007-01-01

    The phospholipid profiles of the myocardium (from 10- and 18-day old chick embryos and 13-day old chick) and their in vitro response to the endogenous lipolytic enzymes (mainly of the phospholipase group) at pH 7.4 and 38 degrees C for 60 min were analyzed by TLC technology and densitometry. Cardiolipin (CL) was shown to be one of the major phospholipids of the chick embryo myocardium and its concentration increased as the chick embryo advanced in development. Monolysocardiolipin (MLCL) was produced subsequent to in vitro incubation of whole tissue homogenates in all myocardia studied as well as a concurrent reduction in CL. This deacylation of CL increased in magnitude as the chick embryo advanced in development indicating its age relatedness. The level of phosphatidyl ethanolamine (PE) plasmalogen was also high in all myocardia studied. Lyso alkenyl PE (LPE) was produced subsequent to in vitro incubation and its level increased as the chick embryo advanced in development, indicating PLA(2) action on the sn-2 fatty acid of PE. Phosphatidyl choline (PC) plasmalogen was also present in the chick embryo myocardium and its level increased gradually as the chick embryo advanced in development. In contrast, yolk-sac membrane contains very minute amounts of CL and PE. No PC was detected and no LPE was formed following in vitro incubation. The yolk of the unfertilized chicken egg has no CL and has very minute amounts of PE, no PC and no lysophospholipids were detected following in vitro incubation in all samples analyzed.

  9. Continuous monitoring of phospholipid vesicle hydrolysis by phospholipase D (PLD) reveals differences in hydrolysis by PLDs from 2 Streptomyces species.

    PubMed

    Hirano, Satomi; Sekine, Kazuhisa; Handa, Tetsurou; Nakano, Minoru

    2012-06-01

    Phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PC) in large unilamellar vesicles (LUVs) consisting of PC and either glycerol monooleate (GMO) or methyl oleate (MeO) were monitored in situ and in real time by using a choline oxidase-immobilized oxygen electrode. This technique revealed reaction differences between 2 bacterial PLDs. PLD from Streptomyces chromofuscus, which is closely homologous to bacterial alkaline phosphatase, hydrolyzed only 6% of surface PC owing to product inhibition. The catalytic activity of this enzyme was not sensitive to the addition of GMO. On the other hand, typical bacterial PLD from Streptomyces sp. was found to hydrolyze all the PC molecules at the outer surface of LUVs suggesting that this enzyme is free from product inhibition. Introduction of GMO or MeO into the bilayer increased exposure of the PC headgroup and facilitated PC hydrolysis mediated by PLD from Streptomyces sp. GMO and MeO have the same lipophilic tail but the latter lacks hydroxyl groups on its polar head. From kinetic analysis by using the Michaelis-Menten model extended to the reaction at the interface, these compounds were found to activate PLD from Streptomyces sp. in different ways, i.e., MeO increased the protein binding to membranes and GMO stimulated the enzyme-substrate complex formation at membrane surface.

  10. Lipoprotein-associated phospholipase A2 as a novel risk marker for cardiovascular disease: a systematic review of the literature.

    PubMed

    Madjid, Mohammad; Ali, Muzammil; Willerson, James T

    2010-01-01

    We sought to critically assess the role of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) in the prediction of cardiovascular events in primary and secondary prevention settings. The inclusion criteria for our study included population-based epidemiologic studies and the presence of clinical outcomes of interest, including atherosclerotic disease, coronary events, stroke, and cardiovascular death. Studies that lacked clinical outcomes or that involved animals were excluded. We included primary and secondary prevention studies of subjects in all ethnic groups and of either sex, with no age limitation. We searched MEDLINE, Google Scholar, and the Cochrane Library for studies with publication dates from January 1970 through July 2009, and we searched major cardiology meeting abstracts from 2000 through 2009. From each study, we used predictive ability-including relative risk, hazard ratio, odds ratio, and prevalence of high Lp-PLA(2) levels, with adjustment-along with baseline population characteristics.Of 33 studies that met our inclusion criteria, 30 showed a significant association between Lp-PLA(2) and cardiovascular events. Most of the studies had been adjusted for major Framingham risk factors and other variables that might influence the effect under question. After multivariate adjustments in cohort and nested case-control studies, increased levels of Lp-PLA(2) remained a significant predictor of cardiovascular events. The available body of evidence suggests that Lp-PLA(2) is a reliable marker of risk for cardiovascular events.

  11. A randomized trial of diet and physical activity in women treated for stage II—IV ovarian cancer: Rationale and design of the Lifestyle Intervention for Ovarian Cancer Enhanced Survival (LIVES): An NRG Oncology/Gynecologic Oncology Group (GOG-225) Study☆,☆☆

    PubMed Central

    Thomson, Cynthia A.; Crane, Tracy E.; Miller, Austin; Garcia, David O.; Basen-Engquist, Karen; Alberts, David S.

    2016-01-01

    Ovarian cancer is the most common cause of gynecological cancer death in United States women. Efforts to improve progression free survival (PFS) and quality of life (QoL) after treatment for ovarian cancer are necessary. Observational studies suggest that lifestyle behaviors, including diet and physical activity, are associated with lower mortality in this population. The Lifestyle Intervention for Ovarian Cancer Enhanced Survival (LIVES) NRG 0225 study is a randomized, controlled trial designed to test the hypothesis that a 24 month lifestyle intervention will significantly increase PFS after oncological therapy for stage II-IV ovarian cancer. Women are randomized 1:1 to a high vegetable and fiber, low-fat diet with daily physical activity goals or an attention control group. Secondary outcomes to be evaluated include QoL and gastrointestinal health. Moreover an a priori lifestyle adherence score will be used to evaluate relationships between adoption of the diet and activity goals and PFS. Blood specimens are collected at baseline, 6, 12 and 24 months for analysis of dietary adherence (carotenoids) in addition to mechanistic biomarkers (lipids, insulin, telomere length). Women are enrolled at NRG clinic sites nationally and the telephone based lifestyle intervention is delivered from The University of Arizona call center by trained health coaches. A study specific multi-modal telephone, email, and SMS behavior change software platform is utilized for information delivery, coaching and data capture. When completed, LIVES will be the largest behavior-based lifestyle intervention trial conducted among ovarian cancer survivors. PMID:27394382

  12. Phospholipase A2 inhibitors protect against prion and Aβ mediated synapse degeneration

    PubMed Central

    2010-01-01

    Background An early event in the neuropathology of prion and Alzheimer's diseases is the loss of synapses and a corresponding reduction in the level of synaptophysin, a pre-synaptic membrane protein essential for neurotransmission. The molecular mechanisms involved in synapse degeneration in these diseases are poorly understood. In this study the process of synapse degeneration was investigated by measuring the synaptophysin content of cultured neurones incubated with the prion derived peptide (PrP82-146) or with Aβ1-42, a peptide thought to trigger pathogenesis in Alzheimer's disease. A pharmacological approach was used to screen cell signalling pathways involved in synapse degeneration. Results Pre-treatment with phospholipase A2 inhibitors (AACOCF3, MAFP and aristolochic acids) protected against synapse degeneration in cultured cortical and hippocampal neurones incubated with PrP82-146 or Aβ1-42. Synapse degeneration was also observed following the addition of a specific phospholipase A2 activating peptide (PLAP) and the addition of PrP82-146 or Aβ1-42 activated cytoplasmic phospholipase A2 within synapses. Activation of phospholipase A2 is the first step in the generation of platelet-activating factor (PAF) and PAF receptor antagonists (ginkgolide B, Hexa-PAF and CV6029) protected against synapse degeneration induced by PrP82-146, Aβ1-42 and PLAP. PAF facilitated the production of prostaglandin E2, which also caused synapse degeneration and pre-treatment with the prostanoid E receptor antagonist AH13205 protected against PrP82-146, Aβ1-42 and PAF induced synapse degeneration. Conclusions Our results are consistent with the hypothesis that PrP82-146 and Aβ1-42trigger abnormal activation of cytoplasmic phospholipase A2 resident within synapses, resulting in elevated levels of PAF and prostaglandin E2that cause synapse degeneration. Inhibitors of this pathway that can cross the blood brain barrier may protect against the synapse degeneration seen during

  13. Angiotensin II induces phosphatidic acid formation in neonatal rat cardiac fibroblasts: evaluation of the roles of phospholipases C and D.

    PubMed

    Booz, G W; Taher, M M; Baker, K M; Singer, H A

    1994-12-21

    Phosphatidic acid has been proposed to contribute to the mitogenic actions of various growth factors. In 32P-labeled neonatal rat cardiac fibroblasts, 100 nM [Sar1]angiotensin II was shown to rapidly induce formation of 32P-phosphatidic acid. Levels peaked at 5 min (1.5-fold above control), but were partially sustained over 2 h. Phospholipase D contributed in part to phosphatidic acid formation, as 32P- or 3H-phosphatidylethanol was produced when cells labeled with [32P]H3PO4 or 1-O-[1,2- 3H]hexadecyl-2-lyso-sn-glycero-3-phosphocholine were stimulated in the presence of 1% ethanol. [Sar1]angiotensin II-induced phospholipase D activity was transient and mainly mediated through protein kinase C (PKC), since PKC downregulation reduced phosphatidylethanol formation by 68%. Residual activity may have been due to increased intracellular Ca2+, as ionomycin also activated phospholipase D in PKC-depleted cells. Phospholipase D did not fully account for [Sar1]angiotensin II-induced phosphatidic acid: 1) compared to PMA, a potent activator of phospholipase D, [Sar1]angiotensin II produced more phosphatidic acid relative to phosphatidylethanol, and 2) PKC downregulation did not affect [Sar1]angiotensin II-induced phosphatidic acid formation. The diacylglycerol kinase inhibitor R59949 depressed [Sar1]angiotensin II-induced phosphatidic acid formation by only 21%, indicating that activation of a phospholipase C and diacylglycerol kinase also can not account for the bulk of phosphatidic acid. Thus, additional pathways not involving phospholipases C and D, such as de novo synthesis, may contribute to [Sar1]angiotensin II-induced phosphatidic acid in these cells. Finally, as previously shown for [Sar1]angiotensin II, phosphatidic acid stimulated mitogen activated protein (MAP) kinase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Astragaloside IV enhances cardioprotection of remote ischemic conditioning after acute myocardial infarction in rats

    PubMed Central

    Cheng, Songy