Science.gov

Sample records for oxidation stimulates calcium

  1. Hydrogen peroxide mediates oxidant-dependent stimulation of arterial smooth muscle L-type calcium channels.

    PubMed

    Chaplin, Nathan L; Amberg, Gregory C

    2012-05-01

    Changes in calcium and redox homeostasis influence multiple cellular processes. Dysregulation of these signaling modalities is associated with pathology in cardiovascular, neuronal, endocrine, and other physiological systems. Calcium and oxidant signaling mechanisms are frequently inferred to be functionally related. To address and clarify this clinically relevant issue in the vasculature we tested the hypothesis that the ubiquitous reactive oxygen molecule hydrogen peroxide mediates oxidant-dependent stimulation of cerebral arterial smooth muscle L-type calcium channels. Using a combinatorial approach including intact arterial manipulations, electrophysiology, and total internal reflection fluorescence imaging, we found that application of physiological levels of hydrogen peroxide to isolated arterial smooth muscle cells increased localized calcium influx through L-type calcium channels. Similarly, oxidant-dependent stimulation of L-type calcium channels by the vasoconstrictor ANG II was abolished by intracellular application of catalase. Catalase also prevented ANG II from increasing localized subplasmalemmal sites of increased oxidation previously associated with colocalized calcium influx through L-type channels. Furthermore, catalase largely attenuated the contractile response of intact cerebral arterial segments to ANG II. In contrast, enhanced dismutation of superoxide to hydrogen peroxide with SOD had no effect on ANG II-dependent stimulation of L-type calcium channels. From these data we conclude that hydrogen peroxide is important for oxidant-dependent regulation of smooth muscle L-type calcium channels and arterial function. These data also support the emerging concept of hydrogen peroxide as a biologically relevant oxidant second messenger in multiple cell types with a diverse array of physiological functions.

  2. Stimulation of calcium-sensing receptors induces endothelium-dependent vasorelaxations via nitric oxide production and activation of IKCa channels

    PubMed Central

    Greenberg, Harry Z.E.; Shi, Jian; Jahan, Kazi S.; Martinucci, Matthew C.; Gilbert, Steven J.; Vanessa Ho, W.-S.; Albert, Anthony P.

    2016-01-01

    Stimulation of vascular calcium-sensing receptors (CaSRs) is reported to induce both constrictions and relaxations. However, cellular mechanisms involved in these responses remain unclear. The present study investigates the effect of stimulating CaSRs on vascular contractility and focuses on the role of the endothelium, nitric oxide (NO) and K+ channels in these responses. In wire myography studies, increasing [Ca2 +]o from 1 mM to 6 mM induced concentration-dependent relaxations of methoxamine pre-contracted rabbit mesenteric arteries. [Ca2 +]o-induced relaxations were dependent on a functional endothelium, and were inhibited by the negative allosteric CaSR modulator Calhex-231. [Ca2 +]o-induced relaxations were reduced by inhibitors of endothelial NO synthase, guanylate cyclase, and protein kinase G. CaSR activation also induced NO production in freshly isolated endothelial cells (ECs) in experiments using the fluorescent NO indicator DAF-FM. Pre-treatment with inhibitors of large (BKCa) and intermediate (IKCa) Ca2 +-activated K+ channels (iberiotoxin and charybdotoxin), and Kv7 channels (linopirdine) also reduced [Ca2 +]o-induced vasorelaxations. Increasing [Ca2 +]o also activated IKCa currents in perforated-patch recordings of isolated mesenteric artery ECs. These findings indicate that stimulation of CaSRs induces endothelium-dependent vasorelaxations which are mediated by two separate pathways involving production of NO and activation of IKCa channels. NO stimulates PKG leading to BKCa activation in vascular smooth muscle cells, whereas IKCa activity contributes to endothelium-derived hyperpolarisations. PMID:26772767

  3. Stimulation of oxidative phosphorylation by calcium in cardiac mitochondria is not influenced by cAMP and PKA activity.

    PubMed

    Covian, Raul; French, Stephanie; Kusnetz, Heather; Balaban, Robert S

    2014-12-01

    Cardiac oxidative ATP generation is finely tuned to match several-fold increases in energy demand. Calcium has been proposed to play a role in the activation of ATP production via PKA phosphorylation in response to intramitochondrial cAMP generation. We evaluated the effect of cAMP, its membrane permeable analogs (dibutyryl-cAMP, 8-bromo-cAMP), and the PKA inhibitor H89 on respiration of isolated pig heart mitochondria. cAMP analogs did not stimulate State 3 respiration of Ca2 +-depleted mitochondria (82.2 ± 3.6% of control), in contrast to the 2-fold activation induced by 0.95 μM free Ca2 +, which was unaffected by H89. Using fluorescence and integrating sphere spectroscopy, we determined that Ca2 + increased the reduction of NADH (8%), and of cytochromes bH (3%), c1 (3%), c (4%), and a (2%), together with a doubling of conductances for Complex I + III and Complex IV. None of these changes were induced by cAMP analogs nor abolished by H89. In Ca2 +-undepleted mitochondria, we observed only slight changes in State 3 respiration rates upon addition of 50 μM cAMP (85 ± 9.9%), dibutyryl-cAMP (80.1 ± 5.2%), 8-bromo-cAMP (88.6 ± 3.3%), or 1 μM H89 (89.7 ± 19.9%) with respect to controls. Similar results were obtained when measuring respiration in heart homogenates. Addition of exogenous PKA with dibutyryl-cAMP or the constitutively active catalytic subunit of PKA to isolated mitochondria decreased State 3 respiration by only 5–15%. These functional studies suggest that alterations in mitochondrial cAMP and PKA activity do not contribute significantly to the acute Ca2 + stimulation of oxidative phosphorylation

  4. Calcium regulation of oxidative phosphorylation in rat skeletal muscle mitochondria.

    PubMed

    Kavanagh, N I; Ainscow, E K; Brand, M D

    2000-02-24

    Activation of oxidative phosphorylation by physiological levels of calcium in mitochondria from rat skeletal muscle was analysed using top-down elasticity and regulation analysis. Oxidative phosphorylation was conceptually divided into three subsystems (substrate oxidation, proton leak and phosphorylation) connected by the membrane potential or the protonmotive force. Calcium directly activated the phosphorylation subsystem and (with sub-saturating 2-oxoglutarate) the substrate oxidation subsystem but had no effect on the proton leak kinetics. The response of mitochondria respiring on 2-oxoglutarate at two physiological concentrations of free calcium was quantified using control and regulation analysis. The partial integrated response coefficients showed that direct stimulation of substrate oxidation contributed 86% of the effect of calcium on state 3 oxygen consumption, and direct activation of the phosphorylation reactions caused 37% of the increase in phosphorylation flux. Calcium directly activated phosphorylation more strongly than substrate oxidation (78% compared to 45%) to achieve homeostasis of mitochondrial membrane potential during large increases in flux.

  5. 21 CFR 582.1210 - Calcium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium oxide. 582.1210 Section 582.1210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1210 Calcium oxide. (a) Product. Calcium oxide. (b) Conditions of use. This substance is...

  6. 21 CFR 582.1210 - Calcium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium oxide. 582.1210 Section 582.1210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1210 Calcium oxide. (a) Product. Calcium oxide. (b) Conditions of use. This substance is...

  7. 21 CFR 582.1210 - Calcium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium oxide. 582.1210 Section 582.1210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1210 Calcium oxide. (a) Product. Calcium oxide. (b) Conditions of use. This substance is...

  8. 21 CFR 582.1210 - Calcium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium oxide. 582.1210 Section 582.1210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1210 Calcium oxide. (a) Product. Calcium oxide. (b) Conditions of use. This substance is...

  9. 21 CFR 582.1210 - Calcium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium oxide. 582.1210 Section 582.1210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1210 Calcium oxide. (a) Product. Calcium oxide. (b) Conditions of use. This substance is...

  10. Crocin Suppresses LPS-Stimulated Expression of Inducible Nitric Oxide Synthase by Upregulation of Heme Oxygenase-1 via Calcium/Calmodulin-Dependent Protein Kinase 4

    PubMed Central

    Kim, Ji-Hee; Park, Ga-Young; Bang, Soo Young; Park, Sun Young; Bae, Soo-Kyung; Kim, YoungHee

    2014-01-01

    Crocin is a water-soluble carotenoid pigment that is primarily used in various cuisines as a seasoning and coloring agent, as well as in traditional medicines for the treatment of edema, fever, and hepatic disorder. In this study, we demonstrated that crocin markedly induces the expression of heme oxygenase-1 (HO-1) which leads to an anti-inflammatory response. Crocin inhibited inducible nitric oxide synthase (iNOS) expression and nitric oxide production via downregulation of nuclear factor kappa B activity in lipopolysaccharide- (LPS-) stimulated RAW 264.7 macrophages. These effects were abrogated by blocking of HO-1 expression or activity. Crocin also induced Ca2+ mobilization from intracellular pools and phosphorylation of Ca2+/calmodulin-dependent protein kinase 4 (CAMK4). CAMK4 knockdown and kinase-dead mutant inhibited crocin-mediated HO-1 expression, Nrf2 activation, and phosphorylation of Akt, indicating that HO-1 expression is mediated by CAMK4 and that Akt is a downstream mediator of CAMK4 in crocin signaling. Moreover, crocin-mediated suppression of iNOS expression was blocked by CAMK4 inhibition. Overall, these results suggest that crocin suppresses LPS-stimulated expression of iNOS by inducing HO-1 expression via Ca2+/calmodulin-CAMK4-PI3K/Akt-Nrf2 signaling cascades. Our findings provide a novel molecular mechanism for the inhibitory effects of crocin against endotoxin-mediated inflammation. PMID:24839356

  11. Studies on endogenous circulating calcium entry blocker and stimulator

    SciTech Connect

    Pang, P.K.T.; Yang, M.C.M.

    1986-03-01

    Several synthetic compounds have been studied extensively for their calcium entry blockade and stimulation in smooth muscles. It is hypothesized that there should be endogenous substances which control calcium entry into cells. We recently investigated the effect of some vasoactive hormones on calcium entry. Our studies on rat tail artery helical strip showed that the in vitro vasoconstriction produced by arginine vasopressin (AVP) decreased stepwise with decreasing concentration of both calcium. After exposure of the tail artery to calcium-free Ringer's solution for 1 minute or longer, the tissue lost its ability to respond to AVP. Subsequent addition of calcium to the medium produced immediate contraction. Measurements of low affinity lanthanum resistant pool of calcium with /sup 45/Ca showed that AVP increased calcium uptake by tail artery in a dose-dependent manner. In another study rat tail artery helical strip indicated that the vasorelaxing action of parathyroid hormone (PTH) was related to an inhibition of calcium uptake. AVP or 60 mM potassium chloride increased the low affinity lanthanum resistant pool of calcium in rate tail artery and PTH inhibited the increase. In conclusion, AVP and PTH may behave like endogenous calcium entry stimulator and inhibitor respectively in vascular tissues.

  12. Stimulation-dependent myocardial calcium uptake into slowly exchangeable compartments

    SciTech Connect

    Fintel, M.; Langer, G.A.

    1986-03-01

    Myocardial calcium uptake into slowly exchangeable sites was increased in response to beating following a period of prolonged quiescence (> 1 hr). Net calcium uptake was measured in rabbit interventricular septa using the /sup 45/Ca washout technique. The maximal increment of slowly exchangeable calcium induced by beating was 20 +/- 2% of calcium uptake during quiescence. The increment in calcium uptake induced by 282 beats in 10 minutes did not differ from the increment induced by 60 beats but was significantly greater than the increment induced by 35 and 15 beats. The total number of beats rather than the frequency of stimulation appeared to be the most critical factor which determined the increment in calcium uptake. Based on the increment of 0.12 +/- 0.02 mmoles/kg dry weight obtained when 15 beats occurred in 10 minutes, the minimum amount of calcium which entered slowly exchangeable sites per beat was calculated to be 1 ..mu..mol/kg wet weight. The increment in slowly exchangeable calcium induced by beating was not affected by ryanodine but was inhibited by the metabolic inhibitor CCCP. In conclusion, a net increment in slowly exchangeable calcium occurs when beating is resumed following a period of prolonged quiescence. This suggests that calcium influx exceeds efflux transiently, under these conditions, and that slowly exchangeable sites represent an important mechanism by which a fraction of incoming calcium is buffered.

  13. Phorbol ester stimulates calcium sequestration in saponized human platelets

    SciTech Connect

    Yoshida, K.; Nachmias, V.T.

    1987-11-25

    When platelets are activated by agonists, calcium (Ca2+) is released from an intracellular storage site. Recent studies using fura-2 show that, after thrombin stimulation, the rise in free calcium is transient and returns to base-line levels in 2-3 min, while the transient following ADP stimulation lasts only 15-20 s. We reported previously that the phorbol ester 12,13-phorbol myristate acetate (PMA), added at nanomolar levels after thrombin, immediately accelerated the rate of return of calcium to the base line severalfold. In the present study, we used both intact and saponized platelets to determine whether this is due to stimulation of calcium sequestration. Using fura-2 and intact platelets, we found 1) that PMA stimulated the restoration of free Ca2+ levels after ADP as well as after thrombin, and 2) that H-7, an inhibitor of protein kinase C (Ca2+/phospholipid-dependent enzyme), slowed the return of Ca2+ to baseline levels. Using saponized platelets, we also found 3) that pretreatment of platelets with PMA before saponin treatment increased the ATP-dependent /sup 45/Ca2+ uptake 2-fold, with a half-maximal effect at 5 nm; 4) that most of the Ca2+ released by ionomycin or by myoinositol 1,4,5-trisphosphate; and 5) that a GTP-binding protein inhibitor, guanosine 5'-O-(2-thiodiphosphate), decreased basal or PMA-stimulated /sup 45/Ca2+ uptake in saponin-treated platelets. Our data suggest that activation of protein kinase C stimulates the sequestration of Ca2+ independently of cAMP or myoinositol 1,4,5-trisphosphate.

  14. 21 CFR 582.5210 - Calcium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium oxide. 582.5210 Section 582.5210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  15. 21 CFR 582.5210 - Calcium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium oxide. 582.5210 Section 582.5210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  16. 21 CFR 582.5210 - Calcium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium oxide. 582.5210 Section 582.5210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  17. 21 CFR 582.5210 - Calcium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium oxide. 582.5210 Section 582.5210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  18. 21 CFR 582.5210 - Calcium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium oxide. 582.5210 Section 582.5210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  19. Stimulation of proangiogenesis by calcium silicate bioactive ceramic.

    PubMed

    Li, Haiyan; Chang, Jiang

    2013-02-01

    Angiogenesis is critical for bone tissue engineering. Stimulating proangiogenesis in an engineered bone construct using bioglass or bioceramic is now attracting much attention. However, the specific ion that plays important roles in the stimulation of proangiogenesis has not yet been elucidated. In this study, calcium silicate (CS), an osteogenic bioceramic containing only Ca and Si ions, significantly stimulated proangiogenesis of human umbilical vein endothelial cells (HUVECs). The determination of the ionic dissolution product indicates that Si ion concentrations of the CS extracts were significantly higher than that of the calcium phosphate ceramic extracts and control medium. However, the concentrations of Ca and P ions of both ceramic extracts and normal medium were at the same level. With the specific Si ion and its effective concentrations, CS extracts stimulated the proliferation of HUVECs, up-regulated the expression of vascular endothelial growth factor, basic fibroblast growth factor and their receptors, and finally stimulated the proangiogenesis. As the Si ion played an important role in osteogenesis stimulated by Si-containing bioceramics, confirmation of the Si ion's specific role and its effective ion concentrations in CS-induced angiogenesis may be extremely useful in designing osteogenic and angiogenic bioactive materials for bone tissue engineering.

  20. Slow Calcium Signals after Tetanic Electrical Stimulation in Skeletal Myotubes

    PubMed Central

    Eltit, José M.; Hidalgo, Jorge; Liberona, José L.; Jaimovich, Enrique

    2004-01-01

    The fluorescent calcium signal from rat myotubes in culture was monitored after field-stimulation with tetanic protocols. After the calcium signal sensitive to ryanodine and associated to the excitation-contraction coupling, a second long-lasting calcium signal refractory to ryanodine was consistently found. The onset kinetics of this slow signal were slightly modified in nominally calcium-free medium, as were both the frequency and number of pulses during tetanus. No signal was detected in the presence of tetrodotoxin. The participation of the dihydropyridine receptor (DHPR) as the voltage sensor for this signal was assessed by treatment with agonist and antagonist dihydropyridines (Bay K 8644 and nifedipine), showing an enhanced and inhibitory response, respectively. In the dysgenic GLT cell line, which lacks the α1S subunit of the DHPR, the signal was absent. Transfection of these cells with the α1S subunit restored the slow signal. In myotubes, the inositol 1,4,5-trisphosphate (IP3) mass increase induced by a tetanus protocol preceded in time the slow calcium signal. Both an IP3 receptor blocker and a phospholipase C inhibitor (xestospongin C and U73122, respectively) dramatically inhibit this signal. Long-lasting, IP3-generated slow calcium signals appear to be a physiological response to activity-related fluctuations in membrane potential sensed by the DHPR. PMID:15111418

  1. Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

    DOEpatents

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

  2. 40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide....

  3. 40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide....

  4. 40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide....

  5. 40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide....

  6. 40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide....

  7. Oxidants as stimulators of signal transduction.

    PubMed

    Suzuki, Y J; Forman, H J; Sevanian, A

    1997-01-01

    Redox (oxidation-reduction) reactions regulate signal transduction. Oxidants such as superoxide, hydrogen peroxide, hydroxyl radicals, and lipid hydroperoxides (i.e., reactive oxygen species) are now realized as signaling molecules under subtoxic conditions. Nitric oxide is also an example of a redox mediator. Reactive oxygen species induce various biological processes such as gene expression by stimulating signal transduction components such as Ca(2+)-signaling and protein phosphorylation. Various oxidants increase cytosolic Ca2+; however, the exact origin of Ca2+ is controversial. Ca2+ may be released from the endoplasmic reticulum, extracellular space, or mitochondria in response to oxidant-influence on Ca2+ pumps, channels, and transporters. Alternatively, oxidants may release Ca2+ from Ca2+ binding proteins. Various oxidants stimulate tyrosine as well as serine/threonine phosphorylation, and direct stimulation of protein kinases and inhibition of protein phosphatases by oxidants have been proposed as mechanisms. The oxidant-stimulation of the effector molecules such as phospholipase A2 as well as the activation of oxidative stress-responsive transcription factors may also depend on the oxidant-mediated activation of Ca(2+)-signaling and/or protein phosphorylation. In addition to the stimulation of signal transduction by oxidants, the observations that ligand-receptor interactions produce reactive oxygen species and that antioxidants block receptor-mediated signal transduction led to a proposal that reactive oxygen species may be second messengers for transcription factor activation, apoptosis, bone resorption, cell growth, and chemotaxis. Physiological significance of the role of biological oxidants in the regulation of signal transduction as well as the mechanisms of the oxidant-stimulation of signal transduction are discussed.

  8. Thermochemistry of calcium oxide and calcium hydroxide in fluoride slags

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Mitchell, A.

    1990-08-01

    Calcium oxide activity in binary CaF2-CaO and ternary CaF2-CaO-Al2O3 and CaF2-CaO-SiO2 slags has been determined by CO2-slag equilibrium experiments at 1400 °C. The carbonate ca-pacity of these slags has also been computed and compared with sulfide capacity data available in the literature. The similarity in trends suggests the possibility of characterizing carbonate capacity as an alternative basicity index for fluoride-base slags. Slag-D2O equilibrium experi-ments are performed at 1400°C with different fluoride-base slags to determine water solubility at two different partial pressures of D2O, employing a new slag sampling technique. A novel isotope tracer detection technique is employed to analyze water in the slags. The water solubility data found show higher values than the previous literature data by an order of magnitude but show a linear relationship with the square root of water vapor partial pressure. The activity of hydroxide computed from the data is shown to be helpful in estimating water solubility in in-dustrial electroslag remelting (ESR) slags.

  9. Calcium-stimulated autophosphorylation site of plant chimeric calcium/calmodulin-dependent protein kinase

    NASA Technical Reports Server (NTRS)

    Sathyanarayanan, P. V.; Siems, W. F.; Jones, J. P.; Poovaiah, B. W.

    2001-01-01

    The existence of two molecular switches regulating plant chimeric Ca(2+)/calmodulin-dependent protein kinase (CCaMK), namely the C-terminal visinin-like domain acting as Ca(2+)-sensitive molecular switch and calmodulin binding domain acting as Ca(2+)-stimulated autophosphorylation-sensitive molecular switch, has been described (Sathyanarayanan, P. V., Cremo, C. R., and Poovaiah, B. W. (2000) J. Biol. Chem. 275, 30417-30422). Here we report the identification of Ca(2+)-stimulated autophosphorylation site of CCaMK by matrix-assisted laser desorption ionization time of flight-mass spectrometry. Thr(267) was confirmed as the Ca(2+)-stimulated autophosphorylation site by post-source decay experiments and by site-directed mutagenesis. The purified T267A mutant form of CCaMK did not show Ca(2+)-stimulated autophosphorylation, autophosphorylation-dependent variable calmodulin affinity, or Ca(2+)/calmodulin stimulation of kinase activity. Sequence comparison of CCaMK from monocotyledonous plant (lily) and dicotyledonous plant (tobacco) suggests that the autophosphorylation site is conserved. This is the first identification of a phosphorylation site specifically responding to activation by second messenger system (Ca(2+) messenger system) in plants. Homology modeling of the kinase and calmodulin binding domain of CCaMK with the crystal structure of calcium/calmodulin-dependent protein kinase 1 suggests that the Ca(2+)-stimulated autophosphorylation site is located on the surface of the kinase and far from the catalytic site. Analysis of Ca(2+)-stimulated autophosphorylation with increasing concentration of CCaMK indicates the possibility that the Ca(2+)-stimulated phosphorylation occurs by an intermolecular mechanism.

  10. Prolactin stimulates the L-type calcium channel-mediated transepithelial calcium transport in the duodenum of male rats.

    PubMed

    Dorkkam, Nitita; Wongdee, Kannikar; Suntornsaratoon, Panan; Krishnamra, Nateetip; Charoenphandhu, Narattaphol

    2013-01-11

    Elevated plasma levels of prolactin (PRL) have been reported in several physiological and pathological conditions, such as lactation, prolactinoma, and dopaminergic antipsychotic drug uses. Although PRL is a calcium-regulating hormone that stimulates intestinal calcium absorption in lactating rats, whether PRL is capable of stimulating calcium absorption in male rats has been elusive. Herein, the transepithelial calcium transport and electrical characteristics were determined in ex vivo duodenal tissues of male rats by Ussing chamber technique. We found that PRL receptors were abundantly present in the basolateral membrane of the duodenal epithelial cells. PRL (200-800 ng/mL) markedly increased the active duodenal calcium transport in a dose-dependent fashion without effect on the transepithelial resistance. The PRL-enhanced active duodenal calcium transport was completely abolished by L-type calcium channel blocker (nifedipine) as well as inhibitors of the major basolateral calcium transporters, namely plasma membrane Ca(2+)-ATPase and Na(+)/Ca(2+) exchanger. Several intracellular mediators, such as JAK2, MEK, PI3K and Src kinase, were involved in the PRL-enhanced transcellular calcium transport. Moreover, PRL also stimulated the paracellular calcium transport in the duodenum of male rats in a PI3K-dependent manner. In conclusion, PRL appeared to be a calcium-regulating hormone in male rats by enhancing the L-type calcium channel-mediated transcellular and the paracellular passive duodenal calcium transport. This phenomenon could help restrict or alleviate negative calcium balance and osteoporosis that often accompany hyperprolactinemia in male patients. PMID:23206706

  11. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese...

  12. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium calcium manganese...

  13. Development of an Inert Anode for Electrowinning in Calcium Chloride-Calcium Oxide Melts

    NASA Astrophysics Data System (ADS)

    Jiao, Shuqiang; Fray, Derek J.

    2010-02-01

    Studies were performed investigating the anodic testing of calcium ruthenate for electrowinning in calcium chloride-calcium oxide melts. The results showed that calcium ruthenate may be suitable as an inert anode in calcium chloride containing melts as it exhibited a low rate of corrosion in melts containing a small amount of calcium oxide, capable of producing oxygen on its surface, and did not contaminate the melt. To reduce the amount of ruthenium in the anode, solid solutions of calcium ruthenate in calcium titanate were investigated. At low concentrations, the solid solution is a semiconductor with a relatively low conductivity at room temperature, but at the temperature of operation, 1173 K, the material is an excellent electronic conductor. The other way of reducing the amount of ruthenium is to coat the solid solution onto a substrate. In this way, the substrate would give the mechanical strength while the coating would give the electrical conductivity and corrosion protection. Calcium ruthenate-based anodes can endure long-term use in the laboratory under an applied electrical field with oxygen being liberated on the anode indicating that these materials are candidates for the electrowining in calcium chloride-calcium oxide melts.

  14. Preparation and properties of calcium oxide from eggshells via calcination

    NASA Astrophysics Data System (ADS)

    Tangboriboon, N.; Kunanuruksapong, R.; Sirivat, A.

    2012-12-01

    Duck eggs are one of the most versatile cooking ingredients in which residue eggshells are discarded. Raw duck eggshells were calcined at temperatures between 300 to 900 °C, for 1, 3, and 5 h. Both the raw and calcined duck eggshells were characterized by FTIR, STA, XRD, XRF, TEM, BET, a particle size analyzer, and an impedance analyzer. The proper calcination conditions are: 900 °C and 1 h, yielding calcium oxide with a purity of 99.06 % w/w. The calcium carbonate of the rhombohedral form (CaCO3) transforms completely into the calcium oxide or lime of the face centered cubic form (CaO) at 900 °C, as shown by XRD diffraction patterns. The transmission electron microscopy (TEM) images of the calcium oxide reveal a moderately good dispersion of nearly uniform particles. The calcium oxide has a white color, a spherical shape, high porosity, and narrow particles size distribution. The percentage of ceramic yield of the calcium oxide is 53.53, as measured by STA (TG-DTA-DTG). The calcium oxide has a N2 adsorption-desorption isotherm indicating the meso-porosity range. The dielectric constant and the electrical conductivity of the calcined calcium oxide are 35 and 1:0×10-6(Ω·m)-1, respectively, at the frequency of 500 Hz.

  15. Stimulation of calcium-sodium exchange in dog red blood cells by hemolysis and resealing.

    PubMed

    Parker, J C

    1988-09-01

    Osmotic hemolysis and resealing greatly increase calcium influx in dog red blood cells. The resealed ghosts show a saturable calcium entry pathway with complex kinetics. As expected for a calcium-sodium exchanger, calcium uptake is stimulated by internal sodium and inhibited by external sodium. Compared to fresh, intact red cells the resealed ghost calcium-sodium exchanger is less responsive to quinidine and to alterations in medium tonicity. The differences in calcium uptake rate among cells from different donors are minimized in the ghost preparation. There are several ways to stimulate sodium-dependent calcium movements in these cells, of which hemolysis-resealing is the most potent. The results of these and previous studies suggest that dog red blood cells have a latent capacity for calcium-sodium exchange. PMID:3415988

  16. Electron stimulated oxidation of silicon surfaces

    SciTech Connect

    Munoz, M.C.; Sacedon, J.L.

    1981-04-15

    Experimental evidence of electron stimulated oxidation (ESO) has been given for Si(111) 7 x 7 surface. In a first stage, the oxide thickness as a function of time shows a linear relationship; in a second stage, the growth rate quickly decreases and a pressure dependent saturation oxide thickness is reached. During the oxidation process an electrical potential does exist across the oxide, as is required in the Cabrera--Mott theory. The linear kinetics and the electrical potential are shown to be explicable in terms of a modified coupled-current approach based on the Cabrera--Mott theory, provided a semiphenomenological pressure dependent parameter is included. This represents a contribution of the surface reaction to the transport equation. The saturation has been explained as due to the decrease of the negative surface charge (donor levels) which produces a decrease of the electron current.

  17. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  18. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  19. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  20. Calcium co-regulates oxidative metabolism and ATP synthase-dependent respiration in pancreatic beta cells.

    PubMed

    De Marchi, Umberto; Thevenet, Jonathan; Hermant, Aurelie; Dioum, Elhadji; Wiederkehr, Andreas

    2014-03-28

    Mitochondrial energy metabolism is essential for glucose-induced calcium signaling and, therefore, insulin granule exocytosis in pancreatic beta cells. Calcium signals are sensed by mitochondria acting in concert with mitochondrial substrates for the full activation of the organelle. Here we have studied glucose-induced calcium signaling and energy metabolism in INS-1E insulinoma cells and human islet beta cells. In insulin secreting cells a surprisingly large fraction of total respiration under resting conditions is ATP synthase-independent. We observe that ATP synthase-dependent respiration is markedly increased after glucose stimulation. Glucose also causes a very rapid elevation of oxidative metabolism as was followed by NAD(P)H autofluorescence. However, neither the rate of the glucose-induced increase nor the new steady-state NAD(P)H levels are significantly affected by calcium. Our findings challenge the current view, which has focused mainly on calcium-sensitive dehydrogenases as the target for the activation of mitochondrial energy metabolism. We propose a model of tight calcium-dependent regulation of oxidative metabolism and ATP synthase-dependent respiration in beta cell mitochondria. Coordinated activation of matrix dehydrogenases and respiratory chain activity by calcium allows the respiratory rate to change severalfold with only small or no alterations of the NAD(P)H/NAD(P)(+) ratio.

  1. Heterogeneous nucleation of calcium oxalate on native oxide surfaces

    SciTech Connect

    Song, L.; Pattillo, M.J.; Graff, G.L.; Campbell, A.A.; Bunker, B.C.

    1994-04-01

    The aqueous deposition of calcium oxalate onto colloidal oxides has been studied as a model system for understanding heterogeneous nucleation processes of importance in biomimetic synthesis of ceramic thin films. Calcium oxalate nucleation has been monitored by measuring induction times for nucleation using Constant Composition techniques and by measuring nucleation densities on extended oxide surfaces using an atomic force microscope. Results show that the dependence of calcium oxalate nucleation on solution supersaturation fits the functional form predicted by classical nucleation theories. Anionic surfaces appear to promote nucleation better than cationic surfaces, lowering the effective energy barrier to heterogeneous nucleation.

  2. Methylene blue adsorption on graphene oxide/calcium alginate composites.

    PubMed

    Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Wang, Yonghao; Wu, Shaoling; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

    2013-06-01

    Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81 mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature.

  3. Stimulation of phosphatidic acid of calcium influx and cyclic GMP synthesis in neuroblastoma cells.

    PubMed

    Ohsako, S; Deguchi, T

    1981-11-10

    Phosphatidic acid added to the medium markedly elevated intracellular cyclic GMP content in cultured neuroblastoma N1E 115 cells. There was a significant elevation of cyclic GMP with 1 micrograms/ml and a maximum (70-fold) elevation with 100 micrograms/ml of phosphatidic acid. Other natural phospholipids did not increase, or increased only slightly, the cyclic GMP content in the cells. The elevation of cyclic GMP content by phosphatidic acid was absolutely dependent on extracellular calcium. Phosphatidic acid stimulated the influx of calcium into neuroblastoma cells 2- to 5-fold. The pattern of the calcium influx induced by phosphatidic acid was comparable to that of cyclic GMP elevation. The stimulation of calcium influx by phosphatidic acid was also observed in cultured heart cells, indicating that phosphatidic acid acts as a calcium ionophore or opens a specific calcium-gate in a variety of cell membranes. Treatment of neuroblastoma cells with phospholipase C increased 32Pi labeling of phosphatidic acid, stimulated the influx of calcium, and elevated the cyclic GMP content in the cells. Thus exogenous as well as endogenous phosphatidic acid stimulates the translocation of calcium across cell membranes and, as a consequence, induces the synthesis of cyclic GMP in the neuroblastoma cells.

  4. Direct chemical reduction of neptunium oxide to neptunium metal using calcium and calcium chloride

    NASA Astrophysics Data System (ADS)

    Squires, Leah N.; Lessing, Paul

    2016-04-01

    A process of direct reduction of neptunium oxide to neptunium metal using calcium metal as the reducing agent is discussed. After reduction of the oxide to metal, the metal is separated by density from the other components of the reaction mixture and can be easily removed upon cooling. The direct reduction technique consistently produces high purity (98%-99% pure) neptunium metal.

  5. Retinal Stimulation on Rabbit Using Complementary Metal Oxide Semiconductor Based Multichip Flexible Stimulator toward Retinal Prosthesis

    NASA Astrophysics Data System (ADS)

    Tokuda, Takashi; Asano, Ryosuke; Sugitani, Sachie; Taniyama, Mari; Terasawa, Yasuo; Nunoshita, Masahiro; Nakauchi, Kazuaki; Fujikado, Takashi; Tano, Yasuo; Ohta, Jun

    2008-04-01

    The Functionality of a complementary metal oxide semiconductor (CMOS) LSI-based, multichip flexible retinal stimulator was demonstrated in retinal stimulation experiments on rabbits. A 1×4-configured multichip stimulator was fabricated for application to experiments on animals. An experimental procedure including surgical operations was developed, and retinal stimulation was performed with the fabricated multichip stimulator. Neural responses on the visual cortex were successfully evoked by the fabricated stimulator. The stimulator is confirmed to be applicable to acute animal experiments.

  6. 21 CFR 184.1210 - Calcium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or... for inspection at the National Archives and Records Administration (NARA). For information on...

  7. 21 CFR 184.1210 - Calcium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or... for inspection at the National Archives and Records Administration (NARA). For information on...

  8. 21 CFR 184.1210 - Calcium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by calcination... National Archives and Records Administration (NARA). For information on the availability of this...

  9. 21 CFR 184.1210 - Calcium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or... for inspection at the National Archives and Records Administration (NARA). For information on...

  10. 21 CFR 184.1210 - Calcium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or... for inspection at the National Archives and Records Administration (NARA). For information on...

  11. The impact of calcium current reversal on neurotransmitter release in the electrically stimulated retina

    NASA Astrophysics Data System (ADS)

    Werginz, Paul; Rattay, Frank

    2016-08-01

    Objective. In spite of intense theoretical and experimental investigations on electrical nerve stimulation, the influence of reversed ion currents on network activity during extracellular stimulation has not been investigated so far. Approach. Here, the impact of calcium current reversal on neurotransmitter release during subretinal stimulation was analyzed with a computational multi-compartment model of a retinal bipolar cell (BC) that was coupled with a four-pool model for the exocytosis from its ribbon synapses. Emphasis was laid on calcium channel dynamics and how these channels influence synaptic release. Main results. Stronger stimulation with anodic pulses caused transmembrane voltages above the Nernst potential of calcium in the terminals and, by this means, forced calcium ions to flow in the reversed direction from inside to the outside of the cell. Consequently, intracellular calcium concentration decreased resulting in a reduced vesicle release or preventing release at all. This mechanism is expected to lead to a pronounced ring-shaped pattern of exocytosis within a group of neighbored BCs when the stronger stimulated cells close to the electrode fail in releasing vesicles. Significance. Stronger subretinal stimulation causes failure of synaptic exocytosis due to reversal of calcium flow into the extracellular space in cells close to the electrode.

  12. Oxidative stress-induced calcium signalling in Aspergillus nidulans.

    PubMed

    Greene, Vilma; Cao, Hong; Schanne, Francis A X; Bartelt, Diana C

    2002-05-01

    The effects of oxidative stress on levels of calcium ion (Ca(2+)) in Aspergillus nidulans were measured using strains expressing aequorin in the cytoplasm (Aeq(cyt)) and mitochondria (Aeq(mt)). When oxidative stress was induced by exposure to 10-mM H(2)O(2), the mitochondrial calcium response (Ca(mt)(2+)) was greater than the change in cytoplasmic calcium (Ca(c)(2+)). The Ca(mt)(2+) response to H(2)O(2) was dose dependent, while the increase in [Ca(c)(2+)] did not change with increasing H(2)O(2). The increase in both [Ca(c)(2+)] and [Ca(mt)(2+)] in response to oxidative stress was enhanced by exposure of cells to Ca(2+). The presence of chelator in the external medium only partially inhibited the Ca(mt)(2+) and Ca(c)(2+) responses to oxidative stress. Reagents that alter calcium fluxes had varied effects on the Ca(mt)(2+) response to peroxide. Ruthenium red blocked the increase in [Ca(mt)(2+)], while neomycin caused an even greater increase in [Ca(mt)(2+)]. Treatment with ruthenium red and neomycin had no effect on the Ca(c)(2+) response. Bafilomycin A and oligomycin had no effect on either the mitochondrial or cytoplasmic response. Inhibitors of both voltage-regulated calcium channels and intracellular calcium release channels inhibited the Ca(2+)-dependent component of the Ca(mt)(2+) response to oxidative stress. We conclude that the more significant Ca(2+) response to oxidative stress occurs in the mitochondria and that both intracellular and extracellular calcium pools can contribute to the increases in [Ca(c)(2+)] and [Ca(mt)(2+)] induced by oxidative stress.

  13. Sulfhydryl oxidation modifies the calcium dependence of ryanodine-sensitive calcium channels of excitable cells.

    PubMed Central

    Marengo, J J; Hidalgo, C; Bull, R

    1998-01-01

    The calcium dependence of ryanodine-sensitive single calcium channels was studied after fusing with planar lipid bilayers sarcoendoplasmic reticulum vesicles isolated from excitable tissues. Native channels from mammalian or amphibian skeletal muscle displayed three different calcium dependencies, cardiac (C), mammalian skeletal (MS), and low fractional open times (low Po), as reported for channels from brain cortex. Native channels from cardiac muscle presented only the MS and C dependencies. Channels with the MS or low Po behaviors showed bell-shaped calcium dependencies, but the latter had fractional open times of <0.1 at all [Ca2+]. Channels with C calcium dependence were activated by [Ca2+] < 10 microM and were not inhibited by increasing cis [Ca2+] up to 0.5 mM. After oxidation with 2,2'-dithiodipyridine or thimerosal, channels with low Po or MS dependencies increased their activity. These channels modified their calcium dependencies sequentially, from low Po to MS and C, or from MS to C. Reduction with glutathione of channels with C dependence (native or oxidized) decreased their fractional open times in 0.5 mM cis [Ca2+], from near unity to 0.1-0.3. These results show that all native channels displayed at least two calcium dependencies regardless of their origin, and that these changed after treatment with redox reagents. PMID:9512024

  14. Calcium/calmodulin‐dependent kinase II and nitric oxide synthase 1‐dependent modulation of ryanodine receptors during β‐adrenergic stimulation is restricted to the dyadic cleft

    PubMed Central

    Dries, Eef; Santiago, Demetrio J.; Johnson, Daniel M.; Gilbert, Guillaume; Holemans, Patricia; Korte, Sanne M.; Roderick, H. Llewelyn

    2016-01-01

    Key points The dyadic cleft, where coupled ryanodine receptors (RyRs) reside, is thought to serve as a microdomain for local signalling, as supported by distinct modulation of coupled RyRs dependent on Ca2+/calmodulin‐dependent kinase II (CaMKII) activation during high‐frequency stimulation.Sympathetic stimulation through β‐adrenergic receptors activates an integrated signalling cascade, enhancing Ca2+ cycling and is at least partially mediated through CaMKII.Here we report that CaMKII activation during β‐adrenergic signalling is restricted to the dyadic cleft, where it enhances activity of coupled RyRs thereby contributing to the increase in diastolic events. Nitric oxide synthase 1 equally participates in the local modulation of coupled RyRs.In contrast, the increase in the Ca2+ content of the sarcoplasmic reticulum and related increase in the amplitude of the Ca2+ transient are primarily protein kinase A‐dependent.The present data extend the concept of microdomain signalling in the dyadic cleft and give perspectives for selective modulation of RyR subpopulations and diastolic events. Abstract In cardiac myocytes, β‐adrenergic stimulation enhances Ca2+ cycling through an integrated signalling cascade modulating L‐type Ca2+ channels (LTCCs), phospholamban and ryanodine receptors (RyRs). Ca2+/calmodulin‐dependent kinase II (CaMKII) and nitric oxide synthase 1 (NOS1) are proposed as prime mediators for increasing RyR open probability. We investigate whether this pathway is confined to the high Ca2+ microdomain of the dyadic cleft and thus to coupled RyRs. Pig ventricular myocytes are studied under whole‐cell voltage‐clamp and confocal line‐scan imaging with Fluo‐4 as a [Ca2+]i indicator. Following conditioning depolarizing pulses, spontaneous RyR activity is recorded as Ca2+ sparks, which are assigned to coupled and non‐coupled RyR clusters. Isoproterenol (ISO) (10 nm) increases Ca2+ spark frequency in both populations of RyRs. However

  15. Electrosynthesis of Biomimetic Manganese-Calcium Oxides for Water Oxidation Catalysis--Atomic Structure and Functionality.

    PubMed

    González-Flores, Diego; Zaharieva, Ivelina; Heidkamp, Jonathan; Chernev, Petko; Martínez-Moreno, Elías; Pasquini, Chiara; Mohammadi, Mohammad Reza; Klingan, Katharina; Gernet, Ulrich; Fischer, Anna; Dau, Holger

    2016-02-19

    Water-oxidizing calcium-manganese oxides, which mimic the inorganic core of the biological catalyst, were synthesized and structurally characterized by X-ray absorption spectroscopy at the manganese and calcium K edges. The amorphous, birnesite-type oxides are obtained through a simple protocol that involves electrodeposition followed by active-site creation through annealing at moderate temperatures. Calcium ions are inessential, but tune the electrocatalytic properties. For increasing calcium/manganese molar ratios, both Tafel slopes and exchange current densities decrease gradually, resulting in optimal catalytic performance at calcium/manganese molar ratios of close to 10 %. Tracking UV/Vis absorption changes during electrochemical operation suggests that inactive oxides reach their highest, all-Mn(IV) oxidation state at comparably low electrode potentials. The ability to undergo redox transitions and the presence of a minor fraction of Mn(III) ions at catalytic potentials is identified as a prerequisite for catalytic activity. PMID:26692571

  16. Mercury Control with Calcium-Based Sorbents and Oxidizing Agents

    SciTech Connect

    Thomas K. Gale

    2005-07-01

    This Final Report contains the test descriptions, results, analysis, correlations, theoretical descriptions, and model derivations produced from many different investigations performed on a project funded by the U.S. Department of Energy, to investigate calcium-based sorbents and injection of oxidizing agents for the removal of mercury. Among the technologies were (a) calcium-based sorbents in general, (b) oxidant-additive sorbents developed originally at the EPA, and (c) optimized calcium/carbon synergism for mercury-removal enhancement. In addition, (d) sodium-tetrasulfide injection was found to effectively capture both forms of mercury across baghouses and ESPs, and has since been demonstrated at a slipstream treating PRB coal. It has been shown that sodium-tetrasulfide had little impact on the foam index of PRB flyash, which may indicate that sodium-tetrasulfide injection could be used at power plants without affecting flyash sales. Another technology, (e) coal blending, was shown to be an effective means of increasing mercury removal, by optimizing the concentration of calcium and carbon in the flyash. In addition to the investigation and validation of multiple mercury-control technologies (a through e above), important fundamental mechanism governing mercury kinetics in flue gas were elucidated. For example, it was shown, for the range of chlorine and unburned-carbon (UBC) concentrations in coal-fired utilities, that chlorine has much less effect on mercury oxidation and removal than UBC in the flyash. Unburned carbon enhances mercury oxidation in the flue gas by reacting with HCl to form chlorinated-carbon sites, which then react with elemental mercury to form mercuric chloride, which subsequently desorbs back into the flue gas. Calcium was found to enhance mercury removal by stabilizing the oxidized mercury formed on carbon surfaces. Finally, a model was developed to describe these mercury adsorption, desorption, oxidation, and removal mechanisms, including

  17. Glucose stimulates calcium-activated chloride secretion in small intestinal cells.

    PubMed

    Yin, Liangjie; Vijaygopal, Pooja; MacGregor, Gordon G; Menon, Rejeesh; Ranganathan, Perungavur; Prabhakaran, Sreekala; Zhang, Lurong; Zhang, Mei; Binder, Henry J; Okunieff, Paul; Vidyasagar, Sadasivan

    2014-04-01

    The sodium-coupled glucose transporter-1 (SGLT1)-based oral rehydration solution (ORS) used in the management of acute diarrhea does not substantially reduce stool output, despite the fact that glucose stimulates the absorption of sodium and water. To explain this phenomenon, we investigated the possibility that glucose might also stimulate anion secretion. Transepithelial electrical measurements and isotope flux measurements in Ussing chambers were used to study the effect of glucose on active chloride and fluid secretion in mouse small intestinal cells and human Caco-2 cells. Confocal fluorescence laser microscopy and immunohistochemistry measured intracellular changes in calcium, sodium-glucose linked transporter, and calcium-activated chloride channel (anoctamin 1) expression. In addition to enhancing active sodium absorption, glucose increased intracellular calcium and stimulated electrogenic chloride secretion. Calcium imaging studies showed increased intracellular calcium when intestinal cells were exposed to glucose. Niflumic acid, but not glibenclamide, inhibited glucose-stimulated chloride secretion in mouse small intestines and in Caco-2 cells. Glucose-stimulated chloride secretion was not seen in ileal tissues incubated with the intracellular calcium chelater BAPTA-AM and the sodium-potassium-2 chloride cotransporter 1 (NKCC1) blocker bumetanide. These observations establish that glucose not only stimulates active Na absorption, a well-established phenomenon, but also induces a Ca-activated chloride secretion. This may explain the failure of glucose-based ORS to markedly reduce stool output in acute diarrhea. These results have immediate potential to improve the treatment outcomes for acute and/or chronic diarrheal diseases by replacing glucose with compounds that do not stimulate chloride secretion.

  18. Arachidonic acid stimulates /sup 45/calcium efflux and HPL release in isolated trophoblast cells

    SciTech Connect

    Zeitler, P.; Murphy, E.; Handwerger, S.

    1986-01-13

    Previous investigations from this laboratory have indicated that arachidonic acid stimulates a rapid, dose-dependent and reversible increase in hPL release which is not dependent on cyclooxygenase or lipoxygenase metabolism. To investigate further the mechanism by which arachidonic acid stimulates the release of hPL, the effect of arachidonic acid on the release of /sup 45/Ca from perifused cells prelabelled with /sup 45/Ca was examined in an enriched cell culture population of term human syncytiotrophoblast. Arachidonic acid (10-100 ..mu..M) stimulated a dose-dependent, rapid, and reversible increase in the release of both /sup 45/Ca and hPL from the perifused placental cells. On the other hand, palmitic acid had little effect on either hPL release or /sup 45/Ca release even at concentrations as high as 100 ..mu..M. Ionophore A23187 (1-10..mu..M) also stimulated a dose-dependent and reversible increase in hPL release. Since arachidonic acid increases the mobilization of cellular calcium, as reflected by the increased /sup 45/calcium efflux, and since an increase in the intracellular calcium concentration appears to stimulate an increase in hPL release, these results suggest that the stimulation of hPL release by arachidonic acid may be due, at least in part, to the effects of the fatty acid on cellular calcium mobilization. 26 references, 5 figures.

  19. 46 CFR 148.230 - Calcium oxide (lime, unslaked).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES CARRIAGE OF BULK SOLID... of this part and the dangerous cargo manifest requirements in § 148.70 of this part do not apply to... (lime, unslaked). (a) When transported by barge, unslaked lime (calcium oxide) must be carried in...

  20. 46 CFR 148.230 - Calcium oxide (lime, unslaked).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES CARRIAGE OF BULK SOLID... of this part and the dangerous cargo manifest requirements in § 148.70 of this part do not apply to... (lime, unslaked). (a) When transported by barge, unslaked lime (calcium oxide) must be carried in...

  1. 46 CFR 148.230 - Calcium oxide (lime, unslaked).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES CARRIAGE OF BULK SOLID... of this part and the dangerous cargo manifest requirements in § 148.70 of this part do not apply to... (lime, unslaked). (a) When transported by barge, unslaked lime (calcium oxide) must be carried in...

  2. 46 CFR 148.230 - Calcium oxide (lime, unslaked).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES CARRIAGE OF BULK SOLID... of this part and the dangerous cargo manifest requirements in § 148.70 of this part do not apply to... (lime, unslaked). (a) When transported by barge, unslaked lime (calcium oxide) must be carried in...

  3. Localization of calcium stimulated adenosine triphosphatase activity in blood vessels of the skeleton

    NASA Technical Reports Server (NTRS)

    Doty, S. B.

    1985-01-01

    Alkaline phosphatase is an enzyme found in bone forming cells which decreases in certain bones as a result of hypogravity or non-weight bearing. This enzyme can also hydrolyze adenosine triphosphate. Therefore, an effort was made to localize calcium-stimulated ATPase by cytochemistry to determine whether altered bone cell activity might be related to changing calcium levels which occur during hypogravity. The results indicate that Ca(++)-ATPase is largely found along the endothelium and basal lamina of blood vessels, and not found in bone forming cells. This suggests that calcium regulation in the vicinity of bone formation may be modulated by the vasculature of the area.

  4. Calcium-sensing receptor regulates stomatal closure through hydrogen peroxide and nitric oxide in response to extracellular calcium in Arabidopsis

    PubMed Central

    Wang, Wen-Hua; Yi, Xiao-Qian; Han, Ai-Dong; Liu, Ting-Wu; Chen, Juan; Wu, Fei-Hua; Dong, Xue-Jun; He, Jun-Xian; Pei, Zhen-Ming; Zheng, Hai-Lei

    2012-01-01

    The Arabidopsis calcium-sensing receptor CAS is a crucial regulator of extracellular calcium-induced stomatal closure. Free cytosolic Ca2+ (Ca2+i) increases in response to a high extracellular calcium (Ca2+o) level through a CAS signalling pathway and finally leads to stomatal closure. Multidisciplinary approaches including histochemical, pharmacological, fluorescent, electrochemical, and molecular biological methods were used to discuss the relationship of hydrogen peroxide (H2O2) and nitric oxide (NO) signalling in the CAS signalling pathway in guard cells in response to Ca2+o. Here it is shown that Ca2+o could induce H2O2 and NO production from guard cells but only H2O2 from chloroplasts, leading to stomatal closure. In addition, the CASas mutant, the atrbohD/F double mutant, and the Atnoa1 mutant were all insensitive to Ca2+o-stimulated stomatal closure, as well as H2O2 and NO elevation in the case of CASas. Furthermore, it was found that the antioxidant system might function as a mediator in Ca2+o and H2O2 signalling in guard cells. The results suggest a hypothetical model whereby Ca2+o induces H2O2 and NO accumulation in guard cells through the CAS signalling pathway, which further triggers Ca2+i transients and finally stomatal closure. The possible cross-talk of Ca2+o and abscisic acid signalling as well as the antioxidant system are discussed. PMID:21940718

  5. Effect of pulse magnetic field stimulation on calcium channel current

    NASA Astrophysics Data System (ADS)

    Fan, J.; Lee, Z. H.; Ng, W. C.; Khoa, W. L.; Teoh, S. H.; Soong, T. H.; Qin, Y. R.; Zhang, Z. Y.; Li, X. P.

    2012-10-01

    This study aimed to investigate the effect of low frequency and high amplitude pulse magnetic field (PMF) on Calcium ion channel current of cells. Measurements were done on the Human Embryonic Kidney 293 cells (HEK 293), which have only Calcium ion channels functioning. The whole cell current was measured by patch clamp method, with the clamped voltage ramping from -90 mV to +50 mV across the cell membrane. A PMF was generated by a 400-turn coil connected to a pulse current generator. The frequency of the pulse was 7 Hz, the width of the pulse was 3 ms, and the amplitude of the pulse, or the flux density, was ranging from 6 to 25 mT. The results showed that the profile of the whole cell Calcium channel current could be modified by the PMF. With the PMF applied, the phase shifting occurred: the onset of the channel opening took place several mili-seconds earlier than that without the PWF and correspondingly, the whole cell current reached its maximum earlier, and the current returned back to zero earlier as well. When the PWF was stopped, these effects persisted for a period of time, and then the current profile "recovered" to its original appearance. The decrease of the onset time and peak current time could be due to the local electric potential induced by the PWF and the direct interaction between PMF and ion channels/ions. The exact mechanisms of the observed effects of PMF on the cell are still unknown and need to be further studied.

  6. [Calcium-induced changes in bilayer membranes from oxidized cholesterol].

    PubMed

    Hianik, T; Miklovichova, J; Foltinova, O; Bajchi, A

    1985-01-01

    Elastic properties of oxidized cholesterol bilayers in n-octane and membrane solvent free were studied by measuring Young modulus E perpendicular in the direction perpendicular to the membrane plane as a function of concentration of calcium ions. Interaction between calcium ions and solvent free bilayers resulted in a significant increases of Young modulus E perpendicular in the concentration range 20-40 mmol/l Ca2+. It is suggested that the hardening of the membrane is caused by some structural changes in the hydrophobic region of the membrane.

  7. Mitochondrial calcium uniporter protein MCU is involved in oxidative stress-induced cell death.

    PubMed

    Liao, Yajin; Hao, Yumin; Chen, Hong; He, Qing; Yuan, Zengqiang; Cheng, Jinbo

    2015-06-01

    Mitochondrial calcium uniporter (MCU) is a conserved Ca(2+) transporter at mitochondrial in eukaryotic cells. However, the role of MCU protein in oxidative stress-induced cell death remains unclear. Here, we showed that ectopically expressed MCU is mitochondrial localized in both HeLa and primary cerebellar granule neurons (CGNs). Knockdown of endogenous MCU decreases mitochondrial Ca(2+) uptake following histamine stimulation and attenuates cell death induced by oxidative stress in both HeLa cells and CGNs. We also found MCU interacts with VDAC1 and mediates VDAC1 overexpression-induced cell death in CGNs. This finding demonstrates that MCU-VDAC1 complex regulates mitochondrial Ca(2+) uptake and oxidative stress-induced apoptosis, which might represent therapeutic targets for oxidative stress related diseases.

  8. Kinetics of calcium sulfoaluminate formation from tricalcium aluminate, calcium sulfate and calcium oxide

    SciTech Connect

    Li, Xuerun Zhang, Yu; Shen, Xiaodong Wang, Qianqian; Pan, Zhigang

    2014-01-15

    The formation kinetics of tricalcium aluminate (C{sub 3}A) and calcium sulfate yielding calcium sulfoaluminate (C{sub 4}A{sub 3}$) and the decomposition kinetics of calcium sulfoaluminate were investigated by sintering a mixture of synthetic C{sub 3}A and gypsum. The quantitative analysis of the phase composition was performed by X-ray powder diffraction analysis using the Rietveld method. The results showed that the formation reaction 3Ca{sub 3}Al{sub 2}O{sub 6} + CaSO{sub 4} → Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 6CaO was the primary reaction < 1350 °C with and activation energy of 231 ± 42 kJ/mol; while the decomposition reaction 2Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 10CaO → 6Ca{sub 3}Al{sub 2}O{sub 6} + 2SO{sub 2} ↑ + O{sub 2} ↑ primarily occurred beyond 1350 °C with an activation energy of 792 ± 64 kJ/mol. The optimal formation region for C{sub 4}A{sub 3}$ was from 1150 °C to 1350 °C and from 6 h to 1 h, which could provide useful information on the formation of C{sub 4}A{sub 3}$ containing clinkers. The Jander diffusion model was feasible for the formation and decomposition of calcium sulfoaluminate. Ca{sup 2+} and SO{sub 4}{sup 2−} were the diffusive species in both the formation and decomposition reactions. -- Highlights: •Formation and decomposition of calcium sulphoaluminate were studied. •Decomposition of calcium sulphoaluminate combined CaO and yielded C{sub 3}A. •Activation energy for formation was 231 ± 42 kJ/mol. •Activation energy for decomposition was 792 ± 64 kJ/mol. •Both the formation and decomposition were controlled by diffusion.

  9. Pentagastrin, calcium and whisky stimulated serum calcitonin in medullary carcinoma of the thyroid.

    PubMed

    Emmertsen, K K; Nielsen, H E; Mosekilde, L; Hansen, H H

    1980-01-01

    The efficiency of pentagastrin, calcium and whisky in raising serum immunoreactive calcitonin (S-iCT) concentrations was analysed in 6 patients with medullary carcinoma of the thyroid and in 8 healthy controls. All 6 patients responded to pentagastrin with a significant increase in S-iCT, 5 responded to calcium and only 3 to whisky. In the 8 controls no or only a modest increase in S-iCT occurred following pentagastrin, calcium and whisky with no difference between the three. It is concluded that pentagastrin is the most useful stimulative agent for ICT secretion in patients with C-cell neoplasms. In selected cases the additional use of calcium could be advantageous.

  10. Stimulation of root elongation and curvature by calcium.

    PubMed

    Takahashi, H; Scott, T K; Suge, H

    1992-01-01

    Ca2+ has been proposed to mediate inhibition of root elongation. However, exogenous Ca2+ at 10 or 20 millimolar, applied directly to the root cap, significantly stimulated root elongation in pea (Pisum sativum L.) and corn (Zea mays L.) seedlings. Furthermore, Ca2+ at 1 to 20 millimolar, applied unilaterally to the caps of Alaska pea roots, caused root curvature away from the Ca2+ source, which was caused by an acceleration of elongation growth on the convex side (Ca2+ side) of the roots. Roots of an agravitropic pea mutant, ageotropum, responded to a greater extent. Roots of Merit and Silver Queen corn also responded to Ca2+ in similar ways but required a higher Ca2+ concentration than that of pea roots. Roots of all other cultivars tested (additional four cultivars of pea and one of corn) curved away from the unilateral Ca2+ source as well. The Ca(2+)-stimulated curvature was substantially enhanced by light. A Ca2+ ionophore, A23187, at 20 micromolar or abscisic acid at 0.1 to 100 micromolar partially substituted for the light effect and enhanced the Ca(2+)-stimulated curvature in the dark. Unilateral application of Ca2+ to the elongation zone of intact roots or to the cut end of detipped roots caused either no curvature or very slight curvature toward the Ca2+. Thus, Ca2+ action on root elongation differs depending on its site of application. The stimulatory action of Ca2+ may involve an elevation of cytoplasmic Ca2+ in root cap cells and may partipate in root tropisms. PMID:11537880

  11. Stimulation of root elongation and curvature by calcium

    NASA Technical Reports Server (NTRS)

    Takahashi, H.; Scott, T. K.; Suge, H.

    1992-01-01

    Ca2+ has been proposed to mediate inhibition of root elongation. However, exogenous Ca2+ at 10 or 20 millimolar, applied directly to the root cap, significantly stimulated root elongation in pea (Pisum sativum L.) and corn (Zea mays L.) seedlings. Furthermore, Ca2+ at 1 to 20 millimolar, applied unilaterally to the caps of Alaska pea roots, caused root curvature away from the Ca2+ source, which was caused by an acceleration of elongation growth on the convex side (Ca2+ side) of the roots. Roots of an agravitropic pea mutant, ageotropum, responded to a greater extent. Roots of Merit and Silver Queen corn also responded to Ca2+ in similar ways but required a higher Ca2+ concentration than that of pea roots. Roots of all other cultivars tested (additional four cultivars of pea and one of corn) curved away from the unilateral Ca2+ source as well. The Ca(2+)-stimulated curvature was substantially enhanced by light. A Ca2+ ionophore, A23187, at 20 micromolar or abscisic acid at 0.1 to 100 micromolar partially substituted for the light effect and enhanced the Ca(2+)-stimulated curvature in the dark. Unilateral application of Ca2+ to the elongation zone of intact roots or to the cut end of detipped roots caused either no curvature or very slight curvature toward the Ca2+. Thus, Ca2+ action on root elongation differs depending on its site of application. The stimulatory action of Ca2+ may involve an elevation of cytoplasmic Ca2+ in root cap cells and may partipate in root tropisms.

  12. Glucose-Stimulated Calcium Dynamics in Islets of Langerhans in Acute Mouse Pancreas Tissue Slices

    PubMed Central

    Stožer, Andraž; Dolenšek, Jurij; Rupnik, Marjan Slak

    2013-01-01

    In endocrine cells within islets of Langerhans calcium ions couple cell stimulation to hormone secretion. Since the advent of modern fluorimetry, numerous in vitro studies employing primarily isolated mouse islets have investigated the effects of various secretagogues on cytoplasmic calcium, predominantly in insulin-secreting beta cells. Due to technical limitations, insights of these studies are inherently limited to a rather small subpopulation of outermost cells. The results also seem to depend on various factors, like culture conditions and duration, and are not always easily reconcilable with findings in vivo. The main controversies regard the types of calcium oscillations, presence of calcium waves, and the level of synchronized activity. Here, we set out to combine the in situ acute mouse pancreas tissue slice preparation with noninvasive fluorescent calcium labeling and subsequent confocal laser scanning microscopy to shed new light on the existing controversies utilizing an innovative approach enabling the characterization of responses in many cells from all layers of islets. Our experiments reproducibly showed stable fast calcium oscillations on a sustained plateau rather than slow oscillations as the predominant type of response in acute tissue slices, and that calcium waves are the mechanistic substrate for synchronization of oscillations. We also found indirect evidence that even a large amplitude calcium signal was not sufficient and that metabolic activation was necessary to ensure cell synchronization upon stimulation with glucose. Our novel method helped resolve existing controversies and showed the potential to help answer important physiological questions, making it one of the methods of choice for the foreseeable future. PMID:23358454

  13. Effect of inotropic stimulation on mitochondrial calcium in cardiac muscle.

    PubMed

    Moravec, C S; Bond, M

    1992-03-15

    Ca(2+)-dependent activation of citric acid cycle enzymes has been demonstrated in isolated cardiac mitochondria. These observations led to the hypothesis that Ca2+ is the signal coupling myofibrillar energy use to mitochondrial energy production in vivo. To test this hypothesis we have measured mitochondrial Ca2+ content during increased energy demand, using electron probe microanalysis. Mitochondrial Ca2+ was measured in hamster papillary muscles rapidly frozen at the peak rate of tension rise under control conditions and after stimulation with the beta-adrenergic agonist isoproterenol (10(-6) M). A third group of muscles was frozen after incubation in low (46.5 mM) Na+ solution to Ca2+ load the cells. Pyruvate dehydrogenase activity was measured in each of the muscles. Isoproterenol caused a 39% increase in force and a 43% increase in pyruvate dehydrogenase activity but no change in mitochondrial Ca2+ (0.46 +/- 0.19 (S.E.) mmol of Ca2+/kg, dry weight) compared with control (0.54 +/- 0.12). In contrast, low Na+ increased pyruvate dehydrogenase activity by 56% and also elevated mitochondrial Ca2+ to 1.28 +/- 0.31 (p less than 0.02). These results demonstrate that mitochondrial Ca2+ is not elevated after inotropic stimulation of cardiac muscle by beta-adrenergic agonists although pyruvate dehydrogenase activity is increased. We conclude that Ca2+ uptake by mitochondria is not a requirement for activation of mitochondrial respiration after increased energy demand. PMID:1544913

  14. Store-operated calcium entry in human oocytes and sensitivity to oxidative stress.

    PubMed

    Martín-Romero, Francisco Javier; Ortíz-de-Galisteo, Jose Ramón; Lara-Laranjeira, Javier; Domínguez-Arroyo, Jose Antonio; González-Carrera, Ernesto; Alvarez, Ignacio S

    2008-02-01

    Calcium signaling is a cellular event that plays a key role at many steps of fertilization and early development. However, little is known regarding the contribution of extracellular Ca(2+) influx into the cell to this signaling in gametes and early embryos. To better know the significance of calcium entry on oocyte physiology, we have evaluated the mechanism of store-operated calcium entry (SOCE) in human metaphase II (MII) oocytes and its sensitivity to oxidative stress, one of the major factors implicated in the outcome of in vitro fertilization (IVF) techniques. We show that depletion of intracellular Ca(2+) stores through inhibition of sarco(endo)plasmic Ca(2+)-ATPase with thapsigargin triggers Ca(2+) entry in resting human oocytes. Ba(2+) and Mn(2+) influx was also stimulated following inhibition, and Ca(2+) entry was sensitive to pharmacological inhibition because the SOCE blocker 2-aminoethoxydiphenylborate (2-APB) reduced calcium and barium entry. These results support the conclusion that there is a plasma membrane mechanism responsible for the capacitative divalent cation entry in human oocytes. Moreover, the Ca(2+) entry mechanism described in MII oocytes was found to be highly sensitive to oxidative stress. Hydrogen peroxide, at micromolar concentrations that could mimic culture conditions in IVF, elicited an increase of [Ca(2+)](i) that was dependent on the presence of extracellular Ca(2+). This rise was preventable by 2-APB, indicating that it was mainly due to the enhanced influx through store-operated calcium channels. In sum, our results demonstrate the occurrence of SOCE in human MII oocytes and the modification of this pathway due to oxidative stress, with possible consequences in IVF. PMID:18003943

  15. Cell stimulation and calcium mobilization by picosecond electric pulses

    PubMed Central

    Semenov, Iurii; Xiao, Shu; Kang, Dongkoo; Schoenbach, Karl H.; Pakhomov, Andrei G.

    2015-01-01

    We tested if picosecond electric pulses (psEP; 190 kV/cm, 500 ps at 50% height), which are much shorter than channel activation time, can activate voltage-gated (VG) channels. Cytosolic Ca2+ was monitored by Fura-2 ratiometric imaging in GH3 and NG108 cells (which express multiple types of VG calcium channels, VGCC), and in CHO cells (which express no VGCC). Trains of up to 100 psEP at 1 kHz elicited no response in CHO cells. However, even a single psEP significantly increased Ca2+ in both GH3 (by 114+/−48 nM) and NG108 cells (by 6 +/−1.1 nM). Trains of 100 psEP amplified the response to 379+/−33 nM and 719+/−315 nM, respectively. Ca2+ responses peaked within 2–15 s and recovered for over 100 s; they were 80–100% inhibited by verapamil and ω-conotoxin, but not by the substitution of Na+ with N-methyl-D-glucamine. There was no response to psEP in Ca2+-free medium, but adding external Ca2+ even 10 s later evoked Ca2+ response. We conclude that electrical stimuli as short as 500 ps can cause long-lasting opening of VGCC by a mechanism which does not involve conventional electroporation, heating (which was under 0.06 °K per psEP), or membrane depolarization by opening of VG Na+ channels. PMID:26011130

  16. Cell stimulation and calcium mobilization by picosecond electric pulses.

    PubMed

    Semenov, Iurii; Xiao, Shu; Kang, Dongkoo; Schoenbach, Karl H; Pakhomov, Andrei G

    2015-10-01

    We tested if picosecond electric pulses (psEP; 190 kV/cm, 500 ps at 50% height), which are much shorter than channel activation time, can activate voltage-gated (VG) channels. Cytosolic Ca(2+) was monitored by Fura-2 ratiometric imaging in GH3 and NG108 cells (which express multiple types of VG calcium channels, VGCC), and in CHO cells (which express no VGCC). Trains of up to 100 psEP at 1 kHz elicited no response in CHO cells. However, even a single psEP significantly increased Ca(2+) in both GH3 (by 114 ± 48 nM) and NG108 cells (by 6 ± 1.1 nM). Trains of 100 psEP amplified the response to 379 ± 33 nM and 719 ± 315 nM, respectively. Ca(2+) responses peaked within 2-15s and recovered for over 100 s; they were 80-100% inhibited by verapamil and ω-conotoxin, but not by the substitution of Na(+) with N-methyl-D-glucamine. There was no response to psEP in Ca(2+)-free medium, but adding external Ca(2+) even 10s later evoked Ca(2+) response. We conclude that electrical stimuli as short as 500 ps can cause long-lasting opening of VGCC by a mechanism which does not involve conventional electroporation, heating (which was under 0.06 K per psEP), or membrane depolarization by opening of VG Na(+) channels.

  17. Cellular texture of mixtures of calcium (magnesium) and yttrium oxides

    SciTech Connect

    Strelov, K.K.; Kamenskikh, V.A.; Gilev, Yu.P.; Udilova, E.Yu.

    1987-08-01

    In solid-phase sintering of calcium (magnesium) oxides with yttrium oxide, the sintered material acquires a cellular texture visible on x-ray photographs obtained in the characteristic yttrium radiation as shown in this paper. Formation of a cellular texture in materials obtained in the systems CaO-Y/sub 2/O/sub 3/ and MgO-Y/sub 2/O/sub 3/ is studied. The practical importance of formation of cellular texture lies in the shielding effect on the surface phase.

  18. Mechanisms for chelator stimulation of microbial Fe(III) -oxide reduction

    USGS Publications Warehouse

    Lovley, D.R.; Woodward, J.C.

    1996-01-01

    The mechanisms by which nitrilotriacetic acid (NTA) stimulated Fe(III) reduction in sediments from a petroleum-contaminated aquifer were investigated in order to gain insight into how added Fe(III) chelators stimulate the activity of hydrocarbon-degrading, Fe(III)-reducing microorganisms in these sediments, and how naturally occurring Fe(III) chelators might promote Fe(III) reduction in aquatic sediments. NTA solubilized Fe(III) from the aquifer sediments. NTA stimulation of microbial Fe(III) reduction did not appear to be the result of making calcium, magnesium, potassium, or trace metals more available to the microorganisms. Stimulation of Fe(III) reduction could not be attributed to NTA serving as a source of carbon or fixed nitrogen for Fe(III)-reducing bacteria as NTA was not degraded in the sediments. Studies with the Fe(III)-reducing microorganism, Geobacter metallireducens, and pure Fe(III)-oxide forms, demonstrated that NTA stimulated the reduction of a variety of Fe(III) forms, including highly crystalline Fe(III)-oxides such as goethite and hematite. The results suggest that NTA solubilization of insoluble Fe(III)-oxide is an important mechanism for the stimulation of Fe(III) reduction by NTA in aquifer sediments.

  19. 40 CFR 721.10600 - Calcium cobalt lead strontium titanium tungsten oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Calcium cobalt lead strontium titanium... Specific Chemical Substances § 721.10600 Calcium cobalt lead strontium titanium tungsten oxide. (a... calcium cobalt lead strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0) is subject...

  20. 40 CFR 721.10600 - Calcium cobalt lead strontium titanium tungsten oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Calcium cobalt lead strontium titanium... Specific Chemical Substances § 721.10600 Calcium cobalt lead strontium titanium tungsten oxide. (a... calcium cobalt lead strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0) is subject...

  1. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.

    PubMed

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

    2013-05-28

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

  2. Protein kinase C modulates cytosolic free calcium by stimulating calcium pump activity in Jurkat T cells.

    PubMed

    Balasubramanyam, M; Gardner, J P

    1995-12-01

    Although protein kinase C (PKC) activation has been shown to inhibit Ca2+ influx in T lymphocytes, the role of PKC on Ca2+ sequestration or extrusion processes has not been fully explored. We examined the effect of CD3 stimulation and PKC activators on cytosolic Ca2+ (Ca2+i) extrusion and 45Ca2+ efflux in human leukemic Jurkat T cells. Treatment of Fura-2 loaded cells with phorbol 12-myristate 13-acetate (PMA) or thymeleatoxin (THYM) resulted in a decrease in Ca2+i both in the presence and absence of extracellular Ca2+, whereas inactive phorbol esters had no effect. PKC activators added at the peak of a Ca2+i transient induced by anti-CD3 mAb, ionomycin or thapsigargin (TG) stimulated the rate and extent of return of Ca2+i to basal levels by 17-53%. PKC stimulation of the Ca2+i decline was not enhanced by the presence of Na+, indicating that PKC activators increase Ca2+ pump activity rather than a Na+/Ca2+ exchange mechanism. As CD3 receptor activation enhanced the Ca2+i decline in TG-treated cells, antigen-mediated activation of phospholipase C (PLC) signaling includes enhanced Ca2+ extrusion at the plasma membrane. The effect of PKC activators on parameters of Ca2+i extrusion were further explored. PMA significantly increased the rate of Ca2+ extrusion in TG-treated cells from 0.28 +/- 0.02 to 0.35 +/- 0.03 s-1 (mean +/- SEM) and stimulated the initial rate of 45Ca2+ efflux by 69% compared to inactive phorbol ester treated cells. The effects of PKC activation on the Ca2+i decline were eliminated by PKC inhibitors, PKC down regulation (24 h PMA pretreatment), ATP-depletion and conditions that inhibited the Ca2+ pump. In contrast, pretreatment of cells with okadaic acid enhanced the PMA-stimulated response. We suggest that Jurkat T cells contain a PKC-sensitive Ca2+ extrusion mechanism likely to be the Ca2+ pump. In lymphocytes, receptor/PLC-linked PKC activation modulates Ca2+i not only by inhibiting Ca2+ influx but also by stimulating plasma membrane Ca2+i

  3. Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels

    PubMed Central

    Hermann, Anton; Sitdikova, Guzel F.; Weiger, Thomas M.

    2015-01-01

    All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences. PMID:26287261

  4. An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation.

    PubMed

    Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Sarvi, Bahram; Haghighi, Behzad

    2015-09-14

    Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts.

  5. An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation.

    PubMed

    Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Sarvi, Bahram; Haghighi, Behzad

    2015-09-14

    Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts. PMID:26017548

  6. Water-oxidation catalysis by synthetic manganese oxides--systematic variations of the calcium birnessite theme.

    PubMed

    Frey, Carolin E; Wiechen, Mathias; Kurz, Philipp

    2014-03-21

    Layered manganese oxides from the birnessite mineral family have been identified as promising heterogeneous compounds for water-oxidation catalysis (WOC), a key reaction for the conversion of renewable energy into storable fuels. High catalytic rates were especially observed for birnessites which contain calcium as part of their structures. With the aim to systematically improve the catalytic performance of such oxide materials, we used a flexible synthetic route to prepare three series of calcium birnessites, where we varied the calcium concentrations, the ripening times of the original precipitates and the temperature of the heat treatment following the initial synthetic steps (tempering) during the preparation process. The products were carefully analysed by a number of analytical techniques and then probed for WOC activity using the Ce(4+)-system. We find that our set of twenty closely related manganese oxides shows large, but somewhat systematic alterations in catalytic rates, indicating the importance of synthesis parameters for maximum catalytic performance. The catalyst of the series for which the highest water-oxidation rate was found is a birnessite of medium calcium content (Ca : Mn ratio 0.2 : 1) that had been subjected to a tempering temperature of 400 °C. On the basis of the detailed analysis of the results, a WOC reaction scheme for birnessites is proposed to explain the observed trends in reactivity. PMID:24225769

  7. beta. -endorphin modulation of mitogen-stimulated calcium uptake by rat thymocytes

    SciTech Connect

    Hemmick, L.M.; Bidlack, J.M.

    1987-10-19

    Lymphocytes stimulated by mitogens or antigens exhibit an enhanced calcium uptake early in the proliferation or activation response. Modulation of this calcium uptake results in alterations of proliferation and immunocompetence. ..beta..-endorphin and other opioids affect several parameters of lymphocyte competence. Limited data are available concerning the mechanism(s) of these effects. This study examines whether a possible opioid mechanism is the modification of the early calcium influx into stimulated lymphocytes. The time course of both concanavalin A (Con A) and phytohemagglutinin (PHA)-stimulated /sup 45/Ca/sup 2 +/ uptake into thymocytes was characterized to determine the optimal time for testing the effects of opioids. BETA-Endorphin 1-31 significantly enhanced Con A-stimulated /sup 45/Ca/sup 2 +/ uptake into rat thymocytes. This peptide had no significant effect on PHA-simulated /sup 45/Ca/sup 2 +/ uptake or on basal thymocyte /sup 45/Ca/sup 2 +/ flux. The ..beta../sub h/-endorphin stimulatory effect was titratable in the range of 0.1 nM to 10 ..mu..M. Naloxone did not reverse the enhancement. Met-enkephalinamide and other opioid agonists did not duplicate the stimulatory effect. Thus, the ..beta../sub h/-endorphin 1-31 enhancement of Con A-stimulated /sup 45/Ca/sup 2 +/ uptake by rat thymocytes does not operate via classical opioid receptor mechanisms. ..beta../sub h/-endorphin 1-31 appears to be acting on a subset of T cells that are responsive to Con A but not to PHA. 30 references, 4 figures, 1 table.

  8. Effects of altered calcium intake on diurnal and calcium-stimulated plasma calcitonin in normal women.

    PubMed

    Tiegs, R D; Heath, H

    1989-06-01

    We sought to determine if any protective effect of dietary calcium (Ca) or Ca supplements on bone could be at least partially mediated by increased calcitonin (CT) secretion. First we studied 10 healthy premenopausal women (median age, 35.5 years) who were randomized to high or low dietary Ca intake (1752 versus 391 mg elemental Ca per day) for 2 weeks and then crossed over. At the end of each dietary period, blood was drawn on 1 day at 0800, 1200, 1700, and 2000 h to assess diurnal variation of plasma CT levels. CT secretory reserve was assessed on the next day by Ca infusion (2 mg Ca per kg body weight over 5 minutes). Next, we studied 10 healthy premenopausal women who took a low-Ca diet (approximately 400 mg Ca per day) for a 2 week control period. The women were then randomized to high- or low-Ca intake [400 mg dietary Ca +/- 1500 mg Ca per day (as supplemental CaCO3)] and then crossed over. At the end of each study period, the diurnal variation in CT was tested on day 1; the CT secretory reserve was assessed on day 3 by an oral Ca load (500 mg as CaCO3)] and on day 5 by Ca infusion. Plasma immunoreactive CT was measured in whole plasma (iCT) and after silica extraction (exCT), predominantly monomeric CT. Neither increased dietary Ca nor Ca supplements affected the diurnal levels of iCT or exCT or augmented plasma CT responses to an oral Ca load.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Iron Mediates N-Methyl-d-aspartate Receptor-dependent Stimulation of Calcium-induced Pathways and Hippocampal Synaptic Plasticity*

    PubMed Central

    Muñoz, Pablo; Humeres, Alexis; Elgueta, Claudio; Kirkwood, Alfredo; Hidalgo, Cecilia; Núñez, Marco T.

    2011-01-01

    Iron deficiency hinders hippocampus-dependent learning processes and impairs cognitive performance, but current knowledge on the molecular mechanisms underlying the unique role of iron in neuronal function is sparse. Here, we investigated the participation of iron on calcium signal generation and ERK1/2 stimulation induced by the glutamate agonist N-methyl-d-aspartate (NMDA), and the effects of iron addition/chelation on hippocampal basal synaptic transmission and long-term potentiation (LTP). Addition of NMDA to primary hippocampal cultures elicited persistent calcium signals that required functional NMDA receptors and were independent of calcium influx through L-type calcium channels or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors; NMDA also promoted ERK1/2 phosphorylation and nuclear translocation. Iron chelation with desferrioxamine or inhibition of ryanodine receptor (RyR)-mediated calcium release with ryanodine-reduced calcium signal duration and prevented NMDA-induced ERK1/2 activation. Iron addition to hippocampal neurons readily increased the intracellular labile iron pool and stimulated reactive oxygen species production; the antioxidant N-acetylcysteine or the hydroxyl radical trapper MCI-186 prevented these responses. Iron addition to primary hippocampal cultures kept in calcium-free medium elicited calcium signals and stimulated ERK1/2 phosphorylation; RyR inhibition abolished these effects. Iron chelation decreased basal synaptic transmission in hippocampal slices, inhibited iron-induced synaptic stimulation, and impaired sustained LTP in hippocampal CA1 neurons induced by strong stimulation. In contrast, iron addition facilitated sustained LTP induction after suboptimal tetanic stimulation. Together, these results suggest that hippocampal neurons require iron to generate RyR-mediated calcium signals after NMDA receptor stimulation, which in turn promotes ERK1/2 activation, an essential step of sustained LTP. PMID:21296883

  10. Mechanisms by which calcium receptor stimulation modifies electromechanical coupling in isolated ventricular cardiomyocytes.

    PubMed

    Schreckenberg, Rolf; Dyukova, Elena; Sitdikova, Guzel; Abdallah, Yaser; Schlüter, Klaus-Dieter

    2015-02-01

    The calcium-sensing receptor (CaR) is widely expressed throughout the entire cardiovascular system and is capable of activating signaling pathways in different cells. Alongside calcium, the CaR also responds to physiological polycations such as putrescine underlining a participation in physiological and pathophysiological processes. Here, we aimed to determine mechanisms as to how CaR activation affects the contractile responsiveness of ventricular cardiomyocytes under basal and stimulated conditions. For that purpose, cardiac myocytes from 3-month-old male Wistar rats were isolated, and the acute effects of an antagonist (NPS2390), agonists (putrescine and gadolinium), or of downregulation of the CaR by siRNA on cell shortening were recorded in a cell-edge-detection system. In addition, experiments were performed on muscle stripes and Langendorff preparations. Mechanistic insights were taken from calcium transients of beating fura-2 AM-loaded cardiomyocytes and western blots. Isolated ventricular cardiomyocytes constitutively express CaR. The expression in the atria is less pronounced. Acute inhibition of CaR reduced basal cell shortening of ventricular myocytes at nearly physiological levels of extracellular calcium. Inhibition of CaR strongly reduced contractility of ventricular muscle stripes but not of atria. Activation of CaR by putrescine and gadolinium influences the contractile responsiveness of isolated cardiomyocytes. Increased calcium mobilization from the sarcoplasmic reticulum via an IP3-dependent mechanism was responsible for amplified systolic calcium transients and a subsequent improvement in cell shortening. Alongside with these effects, activation of CaR increased relaxation velocity of the cells. In conclusion, ventricular CaR expression affects contractile parameters of ventricular heart muscle cells and modifies electromechanical coupling of cardiomyocytes.

  11. Cyanamide route to calcium-manganese oxide foams for water oxidation.

    PubMed

    Baktash, Elham; Zaharieva, Ivelina; Schröder, Marc; Goebel, Caren; Dau, Holger; Thomas, Arne

    2013-12-28

    In nature, photosynthetic water oxidation is efficiently catalysed at a protein-bound μ-oxido Mn4Ca cluster. This cluster consists of earth abundant, non-toxic elements and serves as a paragon for development of synthetic catalysts. In this study we developed porous calcium-manganese oxides with a unique foam-like nanostructure prepared via a facile and robust synthetic route using cyanamide as a porogen. A series of such oxide foams annealed at different temperatures was characterized by TEM, SEM, XRD, N2 physisorption, and X-ray absorption spectroscopy (XAS) in order to correlate crystallinity, atomic structure, surface area and oxidation state of the materials with catalytic activity. Some of the resulting Ca-Mn oxides show high activity as catalysts for water oxidation in the presence of cerium(iv) ammonium nitrate as a non-oxo transfer oxidant. An amorphous calcium-manganese-oxide foam with 130 m(2) g(-1) surface area and Mn oxidation state of +3.6 was identified to be most active; its activity is superior to previously reported Ca-Mn oxides. At the atomic level, this material shares structural motifs with the biological paragon as revealed by dual-edge XAS at the Mn and Ca K-edge. Rather than nanostructure and surface area, the atomic structure of the Ca-Mn oxide and the extent of structural order appear to be crucial determinants of catalytic activity. Fully disordered low-valent Mn materials as well as high-valent but crystalline Mn-Ca oxides are unreactive. Highly disordered variants of layered manganese oxide with Ca and water molecules interfacing layer fragments are most reactive. PMID:24091767

  12. The role of intracellular calcium in A-23187 stimulated and beta-adrenoceptor blocking drug treated blood platelets.

    PubMed

    Nosál, R; Jancinová, V; Petríková, M

    1994-06-15

    A significant concentration-dependent difference was found between beta-adrenoceptor blocking drugs in their ability to inhibit A23187-induced isolated platelet aggregation. In the absence of extracellular calcium ions the following rank order of potency to inhibit calcium ionophore stimulated platelet aggregation was shown: propranolol > bevantolol > alprenolol > metipranolol > oxprenolol > atenolol > pindolol > metoprolol approximately sotalol approximately practolol. The interruption of induced aggregation, as well as inhibition of aggregation, in the absence of extracellular calcium ions indicated interference of inhibitory beta-adrenoceptor blocking drugs with intramembrane or intraplatelet calcium pools activated with A23187. This suggestion was supported by the reversal of the inhibitory effect of beta-adrenoceptor blocking drugs in the presence of extracellular calcium ions. The effect was dose dependent and occurred within 30 sec after calcium administration. The results indicated that inhibitory beta-adrenoceptor blocking drugs, possessing a cationic amphiphilic structure, suppressed calcium mobilization in A23187-stimulated platelets, most probably after entering platelets. This explains why lipophilic drugs are more effective than hydrophilic ones in calcium ionophore A23187-stimulated platelets.

  13. MiR-25 protects cardiomyocytes against oxidative damage by targeting the mitochondrial calcium uniporter.

    PubMed

    Pan, Lei; Huang, Bi-Jun; Ma, Xiu-E; Wang, Shi-Yi; Feng, Jing; Lv, Fei; Liu, Yuan; Liu, Yi; Li, Chang-Ming; Liang, Dan-Dan; Li, Jun; Xu, Liang; Chen, Yi-Han

    2015-03-10

    MicroRNAs (miRNAs) are a class of small non-coding RNAs, whose expression levels vary in different cell types and tissues. Emerging evidence indicates that tissue-specific and -enriched miRNAs are closely associated with cellular development and stress responses in their tissues. MiR-25 has been documented to be abundant in cardiomyocytes, but its function in the heart remains unknown. Here, we report that miR-25 can protect cardiomyocytes against oxidative damage by down-regulating mitochondrial calcium uniporter (MCU). MiR-25 was markedly elevated in response to oxidative stimulation in cardiomyocytes. Further overexpression of miR-25 protected cardiomyocytes against oxidative damage by inactivating the mitochondrial apoptosis pathway. MCU was identified as a potential target of miR-25 by bioinformatical analysis. MCU mRNA level was reversely correlated with miR-25 under the exposure of H2O2, and MCU protein level was largely decreased by miR-25 overexpression. The luciferase reporter assay confirmed that miR-25 bound directly to the 3' untranslated region (UTR) of MCU mRNA. MiR-25 significantly decreased H2O2-induced elevation of mitochondrial Ca2+ concentration, which is likely to be the result of decreased activity of MCU. We conclude that miR-25 targets MCU to protect cardiomyocytes against oxidative damages. This finding provides novel insights into the involvement of miRNAs in oxidative stress in cardiomyocytes.

  14. Absorption of inorganic halides produced from Freon 12 by calcium carbonate containing iron(III) oxide

    SciTech Connect

    Imamura, Seiichiro; Matsuba, Yoichi; Yamada, Etsu; Takai, Kenji; Utani, Kazunori

    1997-09-01

    Inorganic halides produced by the catalytic decomposition of Freon 12 were fixed by calcium carbonate, which is the main component of limestone. Iron(III) oxide, which is present as a contaminant in limestone, promoted the absorption of the halides by calcium carbonate at low temperatures. The supposed action of iron(III) oxide was to first react with inorganic halides, forming iron halides, and, then, transfer them to calcium carbonate to replace carbonate ion in a catalytic way. Thus, calcium carbonate containing iron oxides (limestone) can be used as an effective absorbent for the inorganic halogens produced during the decomposition of Freons.

  15. First evidence on phloem transport of nanoscale calcium oxide in groundnut using solution culture technique

    NASA Astrophysics Data System (ADS)

    Deepa, Manchala; Sudhakar, Palagiri; Nagamadhuri, Kandula Venkata; Balakrishna Reddy, Kota; Giridhara Krishna, Thimmavajjula; Prasad, Tollamadugu Naga Venkata Krishna Vara

    2015-06-01

    Nanoscale materials, whose size typically falls below 100 nm, exhibit novel chemical, physical and biological properties which are different from their bulk counterparts. In the present investigation, we demonstrated that nanoscale calcium oxide particles (n-CaO) could transport through phloem tissue of groundnut unlike the corresponding bulk materials. n-CaO particles are prepared using sol-gel method. The size of the as prepared n-CaO measured (69.9 nm) using transmission electron microscopic technique (TEM). Results of the hydroponics experiment using solution culture technique revealed that foliar application of n-CaO at different concentrations (10, 50, 100, 500, 1,000 ppm) on groundnut plants confirmed the entry of calcium into leaves and stems through phloem compared to bulk source of calcium sprayed (CaO and CaNO3). After spraying of n-CaO, calcium content in roots, shoots and leaves significantly increased. Based on visual scoring of calcium deficiency correction and calcium content in plant parts, we may establish the fact that nanoscale calcium oxide particles (size 69.9 nm) could move through phloem tissue in groundnut. This is the first report on phloem transport of nanoscale calcium oxide particles in plants and this result points to the use of nanoscale calcium oxide particles as calcium source to the plants through foliar application, agricultural crops in particular, as bulk calcium application through foliar nutrition is restricted due to its non-mobility in phloem.

  16. 40 CFR 721.10599 - Calcium cobalt lead titanium tungsten oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Calcium cobalt lead titanium tungsten... Specific Chemical Substances § 721.10599 Calcium cobalt lead titanium tungsten oxide. (a) Chemical... cobalt lead titanium tungsten oxide (PMN P-11-271; CAS No. 1262279-31-1) is subject to reporting...

  17. 40 CFR 721.10599 - Calcium cobalt lead titanium tungsten oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Calcium cobalt lead titanium tungsten... Specific Chemical Substances § 721.10599 Calcium cobalt lead titanium tungsten oxide. (a) Chemical... cobalt lead titanium tungsten oxide (PMN P-11-271; CAS No. 1262279-31-1) is subject to reporting...

  18. Surface phonons and surface reconstruction in calcium doped magnesium oxide

    NASA Astrophysics Data System (ADS)

    Masri, P.; Tasker, P. W.

    1985-01-01

    Static lattice calculation of the structure and energy of calcium doped magnesium oxide have indicated that the surface will be heavily segregated with calcium in accordance with experimental measurement. At moderate temperatures the enthalpy of segregation is sufficient to produce a monolayer coverage of impurity at equilibrium. The phonons for the segregated surface reported here show an instability that was not found in the static calculation. A phonon of imaginary frequency over much of the Brillouin zone indicates that a lower energy structure of larger periodicity should exist. We propose a self-consistent static-dynamic procedure that uses the phonon results to suggest a restructuring that is calculated in a static calculation. The phonon calculation is then repeated. When a lowest energy static calculation gives surface phonons with no softening, we can be confident of the predicted structure. In this case we have predicted a segregation induced surface restructuring. The restructured cell is c(√2 × √2)R45° with half the oxygen ions pushed high out of the surface. The small long wavelength phonon anomaly which remains suggests that there may also be a longer range rumpling of surface cations.

  19. Basic calcium phosphate crystal-induced Egr-1 expression stimulates mitogenesis in human fibroblasts

    SciTech Connect

    Zeng, Xiao R.; Sun Yubo; Wenger, Leonor; Cheung, Herman S. . E-mail: hcheung@med.miami.edu

    2005-05-13

    Previously, we have reported that basic calcium phosphate (BCP) crystals stimulate mitogenesis and synthesis of matrix metalloproteinases in cultured human foreskin and synovial fibroblasts. However, the detailed mechanisms involved are still unclear. In the present study, using RT-PCR and Egr-1 promoter analysis we showed that BCP crystals could stimulate early growth response gene Egr-1 transcription through a PKC{alpha}-dependent p44/p42 MAPK pathway. Using a retrovirus gene expression system (Clontech) to overexpress Egr-1 in human fibroblast BJ-1 cells resulted in promotion of mitogenesis measured either by MTT cell proliferation analysis or by direct cell counting. The results demonstrate that Egr-1 may play a key role in mediating BCP crystal-induced synovial fibroblast mitogenesis.

  20. Oxidation products of calcium and strontium bis(diphenylphosphanide).

    PubMed

    Al-Shboul, Tareq M A; Volland, Gritt; Görls, Helmar; Krieck, Sven; Westerhausen, Matthias

    2012-07-16

    The tetrahydrofuran adducts [(thf)(4)M(PPh(2))(2)] (M = Ca, Sr) are air sensitive and can easily be oxidized by chalcogens. Metalation of diphenylphosphane oxide, diphenylphosphinic acid, and diphenyldithiophosphinic acid as well as salt metathetical approaches of the potassium salts with MI(2) allow the synthesis of [(thf)(4)Ca(OPPh(2))(2)] (1), [(dmso)(2)Ca(O(2)PPh(2))(2)] (2), [(thf)(3)Ca(O(2)PPh(2))I](2) (3), [(thf)(3)Ca(S(2)PPh(2))(2)] (4), [(thf)(2)Ca(Se(2)PPh(2))(2)] (5), [(thf)(3)Sr(S(2)PPh(2))(2)] (6), [(thf)(3)Sr(Se(2)PPh(2))(2)] (7), and [(thf)(2)Ca(O(2)PPh(2))(S(2)PPh(2))](2) (8), respectively. The diphenylphosphinite anion in 1 contains a phosphorus atom in a trigonal pyramidal environment and binds terminally via the oxygen atom to calcium. The diphenylphosphinate anions act as bridging ligands leading to polymeric structures of calcium bis(diphenylphosphinates). Therefore strong Lewis bases such as dimethylsulfoxide (dmso) are required to recrystallize this complex yielding chain-like 2. The chain structure can also be cut into smaller units by ligands which avoid bridging positions such as iodide and diphenyldithiophosphinate (3 and 8, respectively). In general, diphenyldithio- and -diselenophosphinate anions act as terminal ligands and allow the isolation of mononuclear complexes 4 to 7. In these molecules the alkaline earth metals show coordination numbers of six (5) and seven (4, 6, and 7).

  1. Glucose stimulates neurotensin secretion from the rat small intestine by mechanisms involving SGLT1 and GLUT2, leading to cell depolarization and calcium influx.

    PubMed

    Kuhre, Rune Ehrenreich; Bechmann, Louise Ellegaard; Wewer Albrechtsen, Nicolai Jacob; Hartmann, Bolette; Holst, Jens Juul

    2015-06-15

    Neurotensin (NT) is a neurohormone produced in the central nervous system and in the gut epithelium by the enteroendocrine N cell. NT may play a role in appetite regulation and may have potential in obesity treatment. Glucose ingestion stimulates NT secretion in healthy young humans, but the mechanisms involved are not well understood. Here, we show that rats express NT in the gut and that glucose gavage stimulates secretion similarly to oral glucose in humans. Therefore, we conducted experiments on isolated perfused rat small intestine with a view to characterize the cellular pathways of secretion. Luminal glucose (20% wt/vol) stimulated secretion but vascular glucose (5, 10, or 15 mmol/l) was without effect. The underlying mechanisms depend on membrane depolarization and calcium influx, since the voltage-gated calcium channel inhibitor nifedipine and the KATP channel opener diazoxide, which causes hyperpolarization, eliminated the response. Luminal inhibition of the sodium-glucose cotransporter 1 (SGLT1) (by phloridzin) eliminated glucose-stimulated release as well as secretion stimulated by luminal methyl-α-D-glucopyranoside (20% wt/vol), a metabolically inactive SGLT1 substrate, suggesting that glucose stimulates secretion by initial uptake by this transporter. However, secretion was also sensitive to GLUT2 inhibition (by phloretin) and blockage of oxidative phosphorylation (2-4-dinitrophenol). Direct KATP channel closure by sulfonylureas stimulated secretion. Therefore, glucose stimulates NT secretion by uptake through SGLT1 and GLUT2, both causing depolarization either as a consequence of sodium-coupled uptake (SGLT1) or by closure of KATP channels (GLUT2 and SGLT1) secondary to the ATP-generating metabolism of glucose.

  2. Effects of unipolar stimulation on voltage and calcium distributions in the isolated rabbit heart

    PubMed Central

    Sidorov, Veniamin Y.; Holcomb, Mark R.; Woods, Marcella C.; Gray, Richard A.; Wikswo, John P.

    2009-01-01

    Background The effect of electric stimulation on the polarization of cardiac tissue (virtual electrode effect) is well-known; the corresponding response of intracellular calcium concentration ([Ca2+]i) and its dependence on coupling interval between conditioning stimulus (S1) and test stimulus (S2) has yet to be elucidated. Objective Because uncovering the transmembrane potential (Vm) - [Ca2+]i relationship during an electric shock is imperative for understanding arrhythmia induction and defibrillation, we aimed to study simultaneous Vm and [Ca2+]i responses to strong unipolar stimulation. Methods We used a dual-camera optical system to image concurrently Vm and [Ca2+]i responses to unipolar stimulation (20 ms, ±20 mA) in Langendorff-perfused rabbit hearts. RH-237 and Rhod-2 fluorescent dyes were used to measure Vm and [Ca2+]i, respectively. The S1-S2 interval ranged from 10 to 170 ms to examine stimulation during the action potential. Results The [Ca2+]i deflections were less pronounced than changes in Vm for all S1-S2 intervals. For cathodal stimulation, [Ca2+]i at the central virtual cathode region increased with prolongation of S1-S2 interval. For anodal stimulation, [Ca2+]i at the central virtual anode area decreased with shortening of the S1-S2 interval. At very short S1-S2 intervals (10-20 ms), when S2 polarization was superimposed on the S1 action potential upstroke, the [Ca2+]i distribution did not follow Vm and produced a more complex pattern. After S2 termination [Ca2+]i exhibited three outcomes in a manner similar to Vm: non-propagating response, break stimulation, and make stimulation. Conclusions Changes in the [Ca2+]i distribution correlate with the behavior of the Vm distribution for S1-S2 coupling intervals longer than 20 ms; at shorter intervals S2 creates more heterogeneous [Ca2+]i distribution in comparison with Vm. Stimulation in diastole and at very short coupling intervals caused Vm - [Ca2+]i uncoupling at the regions of positive

  3. MERCURY CONTROL WITH CALCIUM-BASED SORBENTS AND OXIDIZING AGENTS

    SciTech Connect

    Thomas K. Gale

    2002-06-01

    The initial tasks of this DOE funded project to investigate mercury removal by calcium-based sorbents have been completed, and initial testing results have been obtained. Mercury monitoring capabilities have been obtained and validated. An approximately 1MW (3.4 Mbtu/hr) Combustion Research Facility at Southern Research Institute was used to perform pilot-scale investigations of mercury sorbents, under conditions representative of full-scale boilers. The initial results of ARCADIS G&M proprietary sorbents, showed ineffective removal of either elemental or oxidized mercury. Benchscale tests are currently underway to ascertain the importance of differences between benchscale and pilot-scale experiments. An investigation of mercury-capture temperature dependence using common sorbents has also begun. Ordinary hydrated lime removed 80 to 90% of the mercury from the flue gas, regardless of the temperature of injection. High temperature injection of hydrated lime simultaneously captured SO{sub 2} at high temperatures and Hg at low temperatures, without any deleterious effects on mercury speciation. Future work will explore alternative methods of oxidizing elemental mercury.

  4. Role of calcium in prolactin-stimulated c-myc gene expression and mitogenesis in Nb2 lymphoma cells

    SciTech Connect

    Murphy, P.R.; DiMattia, G.E.; Friesen, H.G.

    1988-06-01

    Receptor-activated transmembrane calcium flux has been implicated as a mediator of the actions of many growth factors and hormones. We examined the effects of PRL, calcium ionophores, and calcium antagonists on /sup 45/Ca2+ flux, c-myc gene expression, and DNA synthesis in the PRL-dependent rat Nb2 lymphoma cell line. PRL had no detectable effects on /sup 45/Ca2+ uptake or efflux, and the mitogenic effects of PRL could not be reproduced by the calcium ionophore A23187 alone or in combination with the tumor-promoting phorbol ester 12-O-tetra-decanoyl-phorbol-13 acetate (TPA). PRL, but not A23187 or TPA, stimulated c-myc gene expression in quiescent Nb2 cells. Exposure to PRL for brief periods (15 min to 4 h), followed by extensive washing, resulted in a time- and dose-dependent activation of DNA synthesis measured 16 h later. This activation was not blocked by addition of excess anti-PRL antiserum after the wash steps, indicating that the observed stimulation was not due to residual PRL. Despite the marked increase in DNA synthesis, removal of PRL after 4 h prevented mitosis, suggesting that PRL may be required throughout the cell cycle for Nb2 cell proliferation. Although continuous incubation with calcium antagonists resulted in a dose-dependent inhibition of PRL-stimulated DNA synthesis, activation of DNA synthesis by brief exposure to PRL was not inhibited by the presence of EGTA, calcium channel blockers (nifedipine, cobalt chloride), or calmodulin inhibitors (trifluoperazine, N-6-aminohexyl-5-chloronaphthalene sulfonamide). PRL-stimulated c-myc expression was attenuated, but not blocked, by the calcium channel antagonists. However, the putative intracellular calcium antagonist TMB-8 inhibited both c-myc expression and DNA synthesis in a dose-dependent manner (IC50 = 16 microM).

  5. Increased extracellular pressure stimulates tumor proliferation by a mechanosensitive calcium channel and PKC-β.

    PubMed

    Basson, Marc D; Zeng, Bixi; Downey, Christina; Sirivelu, Madhu P; Tepe, Jetze J

    2015-02-01

    Large tumors exhibit high interstitial pressure heightened by growth against the constraining stroma. Such pressures could stimulate tumor proliferation via a mechanosensitive ion channel. We studied the effects of 0-80 mmHg increased extracellular pressure for 24 h on proliferation of SW620, Caco-2, and CT-26 colon; MCF-7 breast; and MLL and PC3 prostate cancer cells, and delineated its mechanism in SW620 cells with specific inhibitors and siRNA. Finally, we compared NF-kB, phospho-IkB and cyclin D1 immunoreactivity in the high pressure centers and low pressure peripheries of human tumors. Pressure-stimulated proliferation in all cells. Pressure-driven SW620 proliferation required calcium influx via the T-type Ca(2+) channel Cav3.3, which stimulated PKC-β to invoke the IKK-IkB-NF-kB pathway to increase proliferation and S-phase fraction. The mitotic index and immunoreactivity of NF-kB, phospho-IkB, and cyclin D1 in the center of 28 large human colon, lung, and head and neck tumors exceeded that in tumor peripheries. Extracellular pressure increases [Ca(2+)]i via Cav3.3, driving a PKC-β- IKK- IkB-NF-kB pathway that stimulates cancer cell proliferation. Rapid proliferation in large stiff tumors may increase intratumoral pressure, activating this pathway to stimulate further proliferation in a feedback cycle that potentiates tumor growth. Targeting this pathway may inhibit proliferation in large unresectable tumors.

  6. Increased extracellular pressure stimulates tumor proliferation by a mechanosensitive calcium channel and PKC-β

    PubMed Central

    Basson, Marc D.; Zeng, Bixi; Downey, Christina; Siriveluprabhakar, Madhu; Tepe, Jetze J.

    2014-01-01

    Large tumors exhibit high interstitial pressure heightened by growth against the constraining stroma. Such pressures could stimulate tumor proliferation via a mechanosensitive ion channel. We studied the effects of 0–80 mm Hg increased extracellular pressure for 24 hours on proliferation of SW620, Caco-2, and CT-26 colon; MCF-7 breast; and MLL and PC3 prostate cancer cells, and delineated its mechanism in SW620 cells with specific inhibitors and siRNA. Finally, we compared NF-kB, phospho-IkB and cyclin D1 immunoreactivity in the high pressure centers and low pressure peripheries of human tumors. Pressure stimulated proliferation in all cells. Pressure-driven SW620 proliferation required calcium influx via the T-type Ca2+ channel Cav3.3, which stimulated PKC-β to invoke the IKK-IkB-NF-kB pathway to increase proliferation and S-phase fraction. The mitotic index and immunoreactivity of NF-kB, phospho-IkB, and cyclin D1 in the center of 28 large human colon, lung, and head and neck tumors exceeded that in tumor peripheries. Extracellular pressure increases [Ca2+]i via Cav3.3, driving a PKC-β-IKK-IkB-NF-kB pathway that stimulates cancer cell proliferation. Rapid proliferation in large stiff tumors may increase intratumoral pressure, activating this pathway to stimulate further proliferation in a feedback cycle that potentiates tumor growth. Targeting this pathway may inhibit proliferation in large unresectable tumors. PMID:25454347

  7. Dissociation of Calcium Transients and Force Development following a Change in Stimulation Frequency in Isolated Rabbit Myocardium

    PubMed Central

    Haizlip, Kaylan M.; Milani-Nejad, Nima; Varian, Kenneth D.; Slabaugh, Jessica L.; Walton, Shane D.; Gyorke, Sandor; Davis, Jonathan P.; Biesiadecki, Brandon J.; Janssen, Paul M. L.

    2015-01-01

    As the heart transitions from one exercise intensity to another, changes in cardiac output occur, which are modulated by alterations in force development and calcium handling. Although the steady-state force-calcium relationship at various heart rates is well investigated, regulation of these processes during transitions in heart rate is poorly understood. In isolated right ventricular muscle preparations from the rabbit, we investigated the beat-to-beat alterations in force and calcium during the transition from one stimulation frequency to another, using contractile assessments and confocal microscopy. We show that a change in steady-state conditions occurs in multiple phases: a rapid phase, which is characterized by a fast change in force production mirrored by a change in calcium transient amplitude, and a slow phase, which follows the rapid phase and occurs as the muscle proceeds to stabilize at the new frequency. This second/late phase is characterized by a quantitative dissociation between the calcium transient amplitude and developed force. Twitch timing kinetics, such as time to peak tension and 50% relaxation rate, reached steady-state well before force development and calcium transient amplitude. The dynamic relationship between force and calcium upon a switch in stimulation frequency unveils the dynamic involvement of myofilament-based properties in frequency-dependent activation. PMID:25961020

  8. Nacre-like calcium carbonate controlled by ionic liquid/graphene oxide composite template.

    PubMed

    Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying

    2015-06-01

    Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed.

  9. Nacre-like calcium carbonate controlled by ionic liquid/graphene oxide composite template.

    PubMed

    Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying

    2015-06-01

    Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed. PMID:25842135

  10. Bicarbonate absorption stimulates active calcium absorption in the rat proximal tubule.

    PubMed Central

    Bomsztyk, K; Calalb, M B

    1988-01-01

    To evaluate the effect of luminal bicarbonate on calcium reabsorption, rat proximal tubules were perfused in vivo. Perfusion solution contained mannitol to reduce water flux to zero. Total Ca concentration was measured by atomic absorption spectrometry, Ca ion concentration in the tubule lumen (CaL2+) and the peritubular capillary (CaP2+), and luminal pH (pHL) with ion-selective microelectrodes and transepithelial voltage (VTE) with conventional microelectrodes. When tubules were perfused with buffer-free Cl-containing solution, net Ca absorption (JCa) averaged 3.33 pmol/min. Even though VTE was 1.64 mV lumen-positive, CaL2+, 1.05 mM, did not fall below the concentration in the capillary blood, 1.07 mM. When 27 mM of Cl was replaced with HCO3, there was luminal fluid acidification. Despite a decrease in VTE and CaL2+, JCa increased to 7.13 pmol/min, indicating that the enhanced JCa could not be accounted for by the reduced electrochemical gradient, delta CCa. When acetazolamide or an analogue of amiloride was added to the HCO3 solution, JCa was not different from the buffer-free solution, suggesting that HCO3-stimulated JCa may be linked to acidification. To further test this hypothesis, we used 27 mM Hepes as the luminal buffer. With Hepes there was luminal fluid acidification and JCa was not different from the buffer-free solution but delta CCa was significantly reduced, indicating enhanced active calcium transport. We conclude from the results of the present study that HCO3 stimulates active Ca absorption, a process that may be linked to acidification-mediated HCO3 absorption. PMID:3366902

  11. Conductivity study of nitrogen-doped calcium zinc oxide prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Hsu, Yu-Ting; Lan, Wen-How; Huang, Kai-Feng; Lin, Jia-Ching; Chang, Kuo-Jen

    2016-01-01

    In this study, the spray pyrolysis method was used to prepare unintentionally doped and nitrogen-doped calcium zinc oxide films by using zinc acetate, calcium nitrate precursor, and ammonium acetate precursor. Morphological and structural analyses were conducted using scanning electron microscopy and X-ray diffraction. The results indicated that film grain size decreased as the nitrogen doping was increased. Both calcium oxide and zinc oxide structures were identified in the unintentionally doped calcium zinc oxide. When nitrogen doping was introduced, the film mainly exhibited a zinc oxide structure with preferred (002) and (101) orientations. The concentration and mobility were investigated using a Hall measurement system. P-type films with a mobility and concentration of 10.6 cm2 V-1 s-1 and 2.8×1017 cm-3, respectively, were obtained. Moreover, according to a temperature-dependent conductivity analysis, an acceptor state with activation energy 0.266 eV dominated the p-type conduction for the unintentionally doped calcium zinc oxide. By contrast, a grain boundary with a barrier height of 0.274-0.292 eV dominated the hole conduction for the nitrogen-doped calcium zinc oxide films.

  12. Deuterium oxide normalizes blood pressure and vascular calcium uptake in Dahl salt-sensitive hypertensive rats

    SciTech Connect

    Vasdev, S.; Prabhakaran, V.; Sampson, C.A. )

    1990-02-01

    This study examined the effect of 25% deuterium oxide in drinking water on systolic blood pressure, uptakes of calcium, and rubidium 86 by aortas of Dahl salt-sensitive rats on 0.4% (low) and 8% (high) sodium chloride (salt) diet. Twenty-four rats were divided into four groups. Groups I and II were on the low salt diet and groups III and IV on the high salt diet from 6 weeks of age. Additionally, at 10 weeks of age groups I and III were placed on 100% water and groups II and IV on 25% deuterium oxide. At 14 weeks, systolic blood pressure, uptakes of calcium, and rubidium 86 by aortas were significantly higher (p less than 0.01) in rats on the high salt diet as compared with those on the low salt diet. Deuterium oxide intake normalized systolic blood pressure and aortic calcium uptake but not aortic rubidium 86 uptake in hypertensive rats on the high salt diet. Deuterium oxide had no effect on blood pressure or aortic calcium uptake in rats on the low salt diet. The parallel increase in systolic blood pressure and vascular calcium uptake suggests that increased calcium uptake mechanisms are associated with hypertension in salt-sensitive Dahl rats. Furthermore, deuterium oxide appears to normalize elevated blood pressure in salt-sensitive hypertensive rats by normalizing elevated vascular (aortic) calcium uptake.

  13. Nanotubes from Oxide-Based Misfit Family: The Case of Calcium Cobalt Oxide.

    PubMed

    Panchakarla, Leela S; Lajaunie, Luc; Ramasubramaniam, Ashwin; Arenal, Raul; Tenne, Reshef

    2016-06-28

    Misfit layered compounds (MLCs) have generated significant interest in recent years as potential thermoelectric materials. MLC nanotubes could reveal behavior that is entirely different from the bulk material. Recently, new chemical strategies were exploited for the synthesis of nanotubular forms of chalcogenide-based MLCs, which are promising candidates for thermoelectric materials. However, analogous synthesis of oxide-based MLC nanotubes has not been demonstrated until now. Here, we report a chemical strategy for synthesis of cobalt-oxide-based misfit nanotubes. A combination of high-resolution (scanning) transmission electron microscopy (including image simulations), spatially resolved electron energy-loss spectroscopy, electron diffraction, and density functional theory (DFT) calculations is used to discover the formation of a phase within these nanotubes that differs significantly from bulk calcium cobaltite MLCs. Furthermore, DFT calculations show that this phase is semiconducting with a band gap in excess of 1 eV, unlike bulk calcium cobaltite MLCs, which are known to be metallic. Through systematic experiments, we propose a formation mechanism for these nanotubes that could also apply more generally to realizing other oxide-based MLC nanotubes. PMID:27215812

  14. Factor Xa stimulates fibroblast procollagen production, proliferation, and calcium signaling via PAR{sub 1} activation

    SciTech Connect

    Blanc-Brude, Olivier P. . E-mail: olivier.blanc-brude@larib.inserm.fr; Archer, Fabienne; Leoni, Patricia; Derian, Claudia; Bolsover, Steven; Laurent, Geoffrey J.; Chambers, Rachel C.

    2005-03-10

    Fibroblast proliferation and procollagen production are central features of tissue repair and fibrosis. In addition to its role in blood clotting, the coagulation cascade proteinase thrombin can contribute to tissue repair by stimulating fibroblasts via proteolytic activation of proteinase-activated receptor-1 (PAR{sub 1}). During hemostasis, the coagulation cascade proteinase factor X is converted into factor Xa. We have previously shown that factor Xa upregulates fibroblast proliferation via production of autocrine PDGF. In this study, we further examined the effects of factor Xa on fibroblast function and aimed to identify its signaling receptor. We showed that factor Xa stimulates procollagen promoter activity and protein production by human and mouse fibroblasts. This effect was independent of PDGF and thrombin production, but dependent on factor Xa proteolytic activity. We also showed that PAR{sub 1}-deficient mouse fibroblasts did not upregulate procollagen production, mobilize cytosolic calcium, or proliferate in response to factor Xa. Desensitization techniques and PAR{sub 1}-specific agonists and inhibitors were used to demonstrate that PAR{sub 1} mediates factor Xa signaling in human fibroblasts. This is the first report that factor Xa stimulates extracellular matrix production. In contrast with endothelial cells and vascular smooth muscle cells, fibroblasts appear to be the only cell type in which the effects of factor Xa are mediated mainly via PAR{sub 1} and not PAR{sub 2}. These findings are critical for our understanding of tissue repair and fibrotic mechanisms, and for the design of novel approaches to inhibit the profibrotic effects of the coagulation cascade without compromising blood hemostasis.

  15. Study on Treatment of acidic and highly concentrated fluoride waste water using calcium oxide-calcium chloride

    NASA Astrophysics Data System (ADS)

    Ren, T.; Gao, X. R.; Zheng, T.; Wang, P.

    2016-08-01

    There are problems with treating acidic waste water containing high concentration fluorine by chemical precipitation, including the low sludge setting velocity and the high difficulty of reaching the criterion. In Heilongjiang province, a graphite factory producing high-purity graphite generates acidic waste water with a high concentration of fluorine. In this paper, the effect of removals on the concentration of fluoride with the combined treatment of calcium oxide and calcium chloride were discussed with regard to acid waste water. The study improved the sludge characteristics by using polyacrylamide (PAM) and polymeric aluminum chloride (PAC). The effect of different coagulants on sludge was evaluated by the sludge settlement ratio (SV), sludge volume index (SVI) and sludge moisture content. The results showed that the optimal combination for 100 ml waste water was calcium oxide addition amount of 14 g, a calcium chloride addition amount of 2.5 g, a PAM addition amount of 350 mg/L, and the effluent fluoride concentration was below 6 mg/L. PAM significantly improved the sludge settling velocity. The sludge settlement ratio reduced from 87.6% to 60%. The process for wastewater treatment was easily operated and involved low expenditure.

  16. Hydrogen peroxide-mediated oxidative stress disrupts calcium binding on calmodulin: More evidence for oxidative stress in vitiligo

    SciTech Connect

    Schallreuter, K.U. . E-mail: k.schallreuter@bradford.ac.uk; Gibbons, N.C.J.; Zothner, C.; Abou Elloof, M.M.; Wood, J.M.

    2007-08-17

    Patients with acute vitiligo have low epidermal catalase expression/activities and accumulate 10{sup -3} M H{sub 2}O{sub 2}. One consequence of this severe oxidative stress is an altered calcium homeostasis in epidermal keratinocytes and melanocytes. Here, we show decreased epidermal calmodulin expression in acute vitiligo. Since 10{sup -3}M H{sub 2}O{sub 2} oxidises methionine and tryptophan residues in proteins, we examined calcium binding to calmodulin in the presence and absence of H{sub 2}O{sub 2} utilising {sup 45}calcium. The results showed that all four calcium atoms exchanged per molecule of calmodulin. Since oxidised calmodulin looses its ability to activate calcium ATPase, enzyme activities were followed in full skin biopsies from lesional skin of patients with acute vitiligo (n = 6) and healthy controls (n = 6). The results yielded a 4-fold decrease of ATPase activities in the patients. Computer simulation of native and oxidised calmodulin confirmed the loss of all four calcium ions from their specific EF-hand domains. Taken together H{sub 2}O{sub 2}-mediated oxidation affects calcium binding in calmodulin leading to perturbed calcium homeostasis and perturbed L-phenylalanine-uptake in the epidermis of acute vitiligo.

  17. Stimulation of sugar uptake and thymidine incorporation in mouse 3T3 cells by calcium phosphate and other extracellular particles.

    PubMed Central

    Barnes, D W; Colowick, S P

    1977-01-01

    Evidence is presented that the marked stimulation of sugar uptake and thymidine incorporation by addition of extra Ca2+ to stationary phase mouse 3T3 cells in culture is phosphate dependent and due to the action of the calcium phosphate precipitate formed in the medium. The cells are similarly stimulated by a variety of particulate materials, including calcium pyrophosphate, barium sulfate, kaolin, and polystrene beads. The precipitate effects on sugar uptake are of the same magnitude as those seen with certain hormones (insulin, epidermal growth factor) or with fresh 10% calf serum. The effect of barium sulfate on thymidine incorporation is also of the same magnitude as seen with these hormones, but much less than half that found with fresh calf serum. The stimulation by barium sulfate or hormones of thymidine incorporation is not phosphate dependent. PMID:202958

  18. Stimulation of sugar uptake and thymidine incorporation in mouse 3T3 cells by calcium phosphate and other extracellular particles.

    PubMed

    Barnes, D W; Colowick, S P

    1977-12-01

    Evidence is presented that the marked stimulation of sugar uptake and thymidine incorporation by addition of extra Ca2+ to stationary phase mouse 3T3 cells in culture is phosphate dependent and due to the action of the calcium phosphate precipitate formed in the medium. The cells are similarly stimulated by a variety of particulate materials, including calcium pyrophosphate, barium sulfate, kaolin, and polystrene beads. The precipitate effects on sugar uptake are of the same magnitude as those seen with certain hormones (insulin, epidermal growth factor) or with fresh 10% calf serum. The effect of barium sulfate on thymidine incorporation is also of the same magnitude as seen with these hormones, but much less than half that found with fresh calf serum. The stimulation by barium sulfate or hormones of thymidine incorporation is not phosphate dependent. PMID:202958

  19. The Role of Calcium in the Response of Osteoblasts to Mechanical Stimulation

    NASA Technical Reports Server (NTRS)

    Duncan, R. L.; Farach-Carson, M. C.; Pavalko, F. M.

    1999-01-01

    A major biomedical concern in the exploration and development of space is the rapid loss of bone associated with extended periods of spaceflight. Mineral content, bone formation, matrix protein production and total body calcium are all reduced during long-term periods of weightlessness. These effects of weightlessness appears to be due to decreases in the anabolic function of osteoblasts and osteocytes rather than changes in the resorptive activity of osteoclasts. Conversely, subjecting the skeleton to exogenous mechanical loading increases matrix protein synthesis and bone formation rate, a process which also appears mediated through osteogenic cells. Osteoblasts have been shown to respond to a number of types of mechanical stimulation. However recently we have demonstrated that osteoblasts respond to fluid shear, but not physiologic levels of mechanical strain, with increases in expression of the matrix protein, osteopontin. We have also shown similar responses in other markers for the anabolic response in bone. The expression of the early response gene, c-fos, and the inducible-isoform of the prostaglandin synthetic enzyme, cyclooygenase-2 (COX-2), both increase rapidly in response to fluid shear, but not strain. How osteoblasts and osteocytes perceive mechanical stimuli and convert this stimulus into a biochemical event within the cell is still unknown. However, examination of the cellular events following mechanical stimulation indicate that two of the earliest responses are a rapid increase in intracellular calcium ([Ca(2+)](sub i)) and a reorganization of the actin cytoskeleton. The increase in [Ca(2+)](sub i) is dependent on the presence of extracellular Ca(2+), suggesting the activation of membrane Ca(2+) channel. We have previously characterized a mechanosensitive, cation-selective channel (MSCC) in osteoblast-like clonal cells, which we postulate is important in this early response to mechanical loading. Using an antisense oligodeoxynucleotide strategy

  20. Calcium

    MedlinePlus

    ... milligrams) of calcium each day. Get it from: Dairy products. Low-fat milk, yogurt, cheese, and cottage ... lactase that helps digest the sugar (lactose) in dairy products, and may have gas, bloating, cramps, or ...

  1. Calcium

    MedlinePlus

    ... supplements and fortified foods include gluconate, lactate, and phosphate. Calcium absorption is best when a person consumes ... also interfere with the body's ability to absorb iron and zinc, but this effect is not well ...

  2. Arterial Calcium Stimulation with Hepatic Venous Sampling in the Localization Diagnosis of Endogenous Hyperinsulinism

    PubMed Central

    Moreno-Moreno, Paloma; Alhambra-Expósito, María Rosa; Palomares-Ortega, Rafel; Zurera-Tendero, Luis; Espejo Herrero, Juan José; Gálvez-Moreno, María Angeles

    2016-01-01

    Objective. The aim of this study was to assess the utility of arterial calcium stimulation with hepatic venous sampling (ASVS) in the localization diagnosis of endogenous hyperinsulinism. Patients and Methods. A retrospective descriptive study was performed including patients with endogenous hyperinsulinism who underwent ASVS. The histopathological diagnosis in patients who underwent a surgical procedure was used as the reference for the statistical study of the accuracy of this technique. Results. 30 patients were included with endogenous hyperinsulinism and nonconclusive imaging diagnosis was included. ASVS was performed in all cases. Surgery was performed in 20 cases. Insulinoma was removed in 19 patients; the location of all cases was detected in the ASVS. All cases of endogenous hyperinsulinism had a positive result for the ASVS, with this association being statistically significant (χ2 = 15.771; p < 0.001). A good and statistically significant agreement was obtained between histopathologic diagnosis and ASVS results (K = 0.518, p < 0.001). Conclusions. ASVS is a useful procedure in the localization diagnosis of endogenous hyperinsulinism undetected by other imaging tests. This technique allows the localization of intrapancreatic insulinomas and represents useful tool for the diagnosis and surgical management of these tumors. PMID:27795707

  3. Comparison of Calcium Phosphate and Zinc Oxide Nanoparticles as Dermal Penetration Enhancers for Albumin.

    PubMed

    Shokri, Narges; Javar, H A

    2015-01-01

    Dermal drug delivery is highly preferred by patients due to its several advantages. Protein therapeutics have attracted huge attention recently. Since dermal delivery of proteins encounter problems, in this investigation, zinc oxide nanoparticles and calcium phosphate nanoparticles were compared as enhancers for dermal permeation of albumin. Albumin was applied simultaneously with zinc oxide nanoparticles or calcium phosphate nanoparticles on pieces of mouse skin. Skin permeation of albumin over time was determined using a diffusion cell. Skin distribution of the nanoparticles and albumin over time was determined by optical and fluorescence microscopy. Zinc oxide nanoparticles and calcium phosphate nanoparticles acted as enhancers for skin permeation of albumin. Cumulative permeated albumin in presence of zinc oxide nanoparticles after 0, 0.5, 1, 1.5 and 2 h, were 0±0, 11.7±3.3, 21.1±3.5, 40.2±3.6 and 40.2±3.6 mg, respectively and in presence of calcium phosphate nanoparticles were 0±0, 20.9±7.4, 33.8±5.5, 33.8±3.7 and 33.8±3.7 mg, respectively. After 0.5 h, little amount of albumin was permeated in presence of every kind of the nanoparticles. After 0.5 or 1 h, the permeated albumin in presence of calcium phosphate nanoparticles was more than that in presence of zinc oxide nanoparticles and after 1.5 h the permeated albumin in presence of zinc oxide nanoparticles was more than that in presence of calcium phosphate nanoparticles. Images of skin distribution of the two nanoparticles over time, were somewhat different and distribution of albumin correlated with the distribution of the nanoparticles alone. The profiles of albumin permeation (in presence of each of the nanoparticles) versus time was delayed and linear for both nanoparticles while the slope for calcium phosphate nanoparticles was higher than zinc oxide nanoparticles. The enhancer effect of zinc oxide nanoparticles was stronger while the enhancer effect of calcium phosphate nanoparticles was

  4. Comparison of calcium hydroxide and zinc oxide and eugenol pulpectomies in primary teeth of dogs.

    PubMed

    Hendry, J A; Jeansonne, B G; Dummett, C O; Burrell, W

    1982-10-01

    The purpose of this investigation was to compare calcium hydroxide with zinc oxide and eugenol (ZOE) as root canal obturants in the pulpectomy procedure for irreversibly inflamed primary pulps of dogs. Clinical, radiographic, and histologic comparisons of calcium hydroxide and ZOE root canal filling materials were made in forty-two primary premolars of seven mongrel puppies. When the animals were 6 weeks of age, the pulps of all samples teeth were extirpated and the canals left open to the oral environment. The root canals were assigned to calcium hydroxide, ZOE, and control groups, instrumented, and filled 2 weeks later. The animals were killed 1 day, 1 week, 4 weeks, and 12 weeks after filling. Statistical analysis of all categories for comparison at 4 weeks indicated that calcium hydroxide gave significantly more favorable results than ZOE. Canals treated with calcium hydroxide exhibited less inflammation, less resorption, and more hard-tissue apposition than ZOE-treated and control groups.

  5. WETTING STIMULATES ATMOSPHERIC CH4 OXIDATION BY ALPINE SOIL (R823442)

    EPA Science Inventory

    Studies were done to assess the effects of soil moisture manipulations on CH4 oxidation in soils from a dry alpine tundra site. When water was added to these soils there was a stimulation of CH4 oxidation. This stimulation of CH4 oxidation took ti...

  6. Calcium.

    PubMed

    Williams, Robert J P

    2002-01-01

    This chapter describes the chemical and biological value of the calcium ion. In calcium chemistry, our main interest is in equilibria within static, nonflowing systems. Hence, we examined the way calcium formed precipitates and complex ions in solution. We observed thereafter its uses by humankind in a vast number of materials such as minerals, e.g., marble, concrete, mortars, which parallel the biological use in shells and bones. In complex formation, we noted that many combinations were of anion interaction with calcium for example in the uses of detergents and medicines. The rates of exchange of calcium from bound states were noted but they had little application. Calcium ions do not act as catalysts of organic reactions. In biological systems, interest is in the above chemistry, but extends to the fact that Ca2+ ions can carry information by flowing in one solution or from one solution to another through membranes. Hence, we became interested in the details of rates of calcium exchange. The fast exchange of this divalent ion from most organic binding sites has allowed it to develop as the dominant second messenger. Now the flow can be examined in vitro as calcium binds particular isolated proteins, which it activates as seen in physical mechanical changes or chemical changes and this piece-by-piece study of cells is common. Here, however, we have chosen to stress the whole circuit of Ca2+ action indicating that the cell is organized both at a basal and an activated state kinetic level by the steady state flow of the ion (see Fig. 11). Different time constants of exchange utilizing very similar binding constants lead to: 1) fast responses as in the muscle of an animal; or 2) slower change as in differentiation of an egg or seed. Many other changes of state may relate to Ca2+ steady-state levels of flow in the circuitry and here we point to two: 1) dormancy in reptiles and animals; and 2) sporulation in both bacteria and lower plants. In the other chapters of

  7. Purinergic stimulation of rabbit ciliated airway epithelia: control by multiple calcium sources.

    PubMed Central

    Korngreen, A; Priel, Z

    1996-01-01

    1. Simultaneous measurements of average intracellular calcium concentration ([Ca2+]i) and ciliary beat frequency (CBF) were carried out on ciliated rabbit tracheal cells in order to determine quantitatively the role of calcium in the regulation of mucus-transporting cilia. 2. Extracellular ATP caused a rapid increase in both [Ca2+]i and CBF in the 0.1-1000 microM concentration range. The rise in [Ca2+]i levelled off to an elevated [Ca2+]i plateau while the cilia remained in a high activation state. The magnitude of the rise in [Ca2+]i and CBF as well as the value of the elevated [Ca2+]i plateau and the value of the sustained CBF were dependent on the concentration of ATP in the solution. 3. No correlation was found between the mean values of [Ca2+]i and CBF at rest but a sigmoidal relationship was found to exist between the maximal rises of these parameters following excitation with extracellular ATP. This sigmoidal correlation incorporated the experiments where [Ca2+]i rise was induced by depletion of internal calcium stores with thapsigargin or by entry of calcium induced by ionomycin. 4. Extracellular ATP caused both the release of calcium from internal stores and calcium influx from the extracellular solution. The release of calcium was identified as originating from a thapsigargin-sensitive and a thapsigargin-insensitive calcium store. It is suggested that the release of calcium from these stores induces the initial rise in CBF. 5. The sustained activation of the cilia and elevated calcium plateau were found to be the result of the extracellular ATP-induced calcium influx. This calcium influx was insensitive to the voltage-gated calcium channel inhibitors verapamil and diltiazem, but was completely eliminated by lowering the extracellular calcium concentration to 0.1 microM. 6. We propose that the initial jump in the CBF is mediated by the calcium released from a thapsigargin-insensitive calcium store adjacent to the cilia, while the later, and longer, rise in

  8. Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Cao, Huiliang; Qin, Hui; Zhao, Yaochao; Jin, Guodong; Lu, Tao; Meng, Fanhao; Zhang, Xianlong; Liu, Xuanyong

    2016-02-01

    Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices.

  9. Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus

    PubMed Central

    Cao, Huiliang; Qin, Hui; Zhao, Yaochao; Jin, Guodong; Lu, Tao; Meng, Fanhao; Zhang, Xianlong; Liu, Xuanyong

    2016-01-01

    Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices. PMID:26899567

  10. Calcium-dependent modulation by ethanol of mouse synaptosomal pyroglutamyl aminopeptidase activity under basal and K(+)-stimulated conditions.

    PubMed

    Mayas, M D; Ramírez-Expósito, M J; García, M J; Tsuboyama, G; Ramírez, M; Martínez-Martos, J M

    2000-11-01

    We studied the in vitro effects of ethanol (25, 50 and 100 mM) on pyroglutamyl aminopeptidase activity (pGluAP), which has been reported as thyrotrophin-releasing-hormone-degrading activity. pGluAP was measured in presence or absence of calcium, under basal and K(+)-stimulated conditions, in synaptosomes and their incubation supernatant, using pyroglutamyl-beta-naphthylamide as substrate. In basal conditions, in synaptosomes, pGluAP was inhibited by ethanol in a calcium-independent way. In the supernatant, the response differed depending on the concentration of ethanol. Depolarization with K(+) modified pGluAP in synaptosomes and supernatant depending on the presence or not of calcium. In synaptosomes, in absence of calcium, the activity was inhibited at the highest concentrations of ethanol. In contrast, in the supernatant, under depolarizing conditions, ethanol increases pGluAP in absence of calcium. These changes may be in part responsible of the behavioural changes associated to alcohol intake.

  11. Rapid and Localized Mechanical Stimulation and Adhesion Assay: TRPM7 Involvement in Calcium Signaling and Cell Adhesion.

    PubMed

    Nishitani, Wagner Shin; Alencar, Adriano Mesquita; Wang, Yingxiao

    2015-01-01

    A cell mechanical stimulation equipment, based on cell substrate deformation, and a more sensitive method for measuring adhesion of cells were developed. A probe, precisely positioned close to the cell, was capable of a vertical localized mechanical stimulation with a temporal frequency of 207 Hz, and strain magnitude of 50%. This setup was characterized and used to probe the response of Human Umbilical Endothelial Vein Cells (HUVECs) in terms of calcium signaling. The intracellular calcium ion concentration was measured by the genetically encoded Cameleon biosensor, with the Transient Receptor Potential cation channel, subfamily M, member 7 (TRPM7) expression inhibited. As TRPM7 expression also regulates adhesion, a relatively simple method for measuring adhesion of cells was also developed, tested and used to study the effect of adhesion alone. Three adhesion conditions of HUVECs on polyacrylamide gel dishes were compared. In the first condition, the substrate is fully treated with Sulfo-SANPAH crosslinking and fibronectin. The other two conditions had increasingly reduced adhesion: partially treated (only coated with fibronectin, with no use of Sulfo-SANPAH, at 5% of the normal amount) and non-treated polyacrylamide gels. The cells showed adhesion and calcium response to the mechanical stimulation correlated to the degree of gel treatment: highest for fully treated gels and lowest for non-treated ones. TRPM7 inhibition by siRNA on HUVECs caused an increase in adhesion relative to control (no siRNA treatment) and non-targeting siRNA, but a decrease to 80% of calcium response relative to non-targeting siRNA which confirms the important role of TRPM7 in mechanotransduction despite the increase in adhesion.

  12. Aldosterone increases kidney tubule cell oxidants through calcium-mediated activation of NADPH oxidase and nitric oxide synthase.

    PubMed

    Queisser, Nina; Schupp, Nicole; Stopper, Helga; Schinzel, Reinhard; Oteiza, Patricia I

    2011-12-01

    Chronic hyperaldosteronism has been associated with an increased cancer risk. We recently showed that aldosterone causes an increase in cell oxidants, DNA damage, and NF-κB activation. This study investigated the mechanisms underlying aldosterone-induced increase in cell oxidants in kidney tubule cells. Aldosterone caused an increase in both reactive oxygen and reactive nitrogen (RNS) species. The involvement of the activation of NADPH oxidase in the increase in cellular oxidants was demonstrated by the inhibitory action of the NADPH oxidase inhibitors DPI, apocynin, and VAS2870 and by the migration of the p47 subunit to the membrane. NADPH oxidase activation occurred as a consequence of an increase in cellular calcium levels and was mediated by protein kinase C. The prevention of RNS increase by BAPTA-AM, W-7, and L-NAME indicates a calcium-calmodulin activation of NOS. A similar pattern of effects of the NADPH oxidase and NOS inhibitors was observed for aldosterone-induced DNA damage and NF-κB activation, both central to the pathogenesis of chronic aldosteronism. In summary, this paper demonstrates that aldosterone, via the mineralocorticoid receptor, causes an increase in kidney cell oxidants, DNA damage, and NF-κB activation through a calcium-mediated activation of NADPH oxidase and NOS. Therapies targeting calcium, NOS, and NADPH oxidase could prevent the adverse effects of hyperaldosteronism on kidney function as well as its potential oncogenic action.

  13. Long-term prolactin exposure differentially stimulated the transcellular and solvent drag-induced calcium transport in the duodenum of ovariectomized rats.

    PubMed

    Tudpor, Kukiat; Charoenphandhu, Narattaphol; Saengamnart, Wasana; Krishnamra, Nateetip

    2005-12-01

    Prolactin, having been shown to stimulate transcellular active and solvent drag-induced calcium transport in the duodenum of female rats, was postulated to improve duodenal calcium transport in estrogen-deficient rats. The aim of the present study was, therefore, to demonstrate the effects of long-term prolactin exposure produced by anterior pituitary (AP) transplantation on the duodenal calcium transport in young (9-week-old) and adult (22-week-old) ovariectomized rats. We found that ovariectomy did not alter the transcellular active duodenal calcium transport in young and adult rats fed normal calcium diet (1.0% w/w Ca) but decreased the solvent drag-induced duodenal calcium transport from 75.50 +/- 10.12 to 55.75 +/- 4.77 nmol.hr(-1).cm(-2) (P < 0.05) only in adult rats. Long-term prolactin exposure stimulated the transcellular active calcium transport in young and adult AP-grafted ovariectomized rats fed with normal calcium diet by more than 2-fold from 7.56 +/- 0.79 to 16.54 +/- 2.05 (P < 0.001) and 9.78 +/- 0.72 to 15.99 +/- 1.75 (P < 0.001) nmol.hr(-1).cm(-2), respectively. However, only the solvent drag-induced duodenal calcium transport in young rats was enhanced by prolactin from 95.51 +/- 10.64 to 163.20 +/- 18.03 nmol.hr(-1).cm(-2) (P < 0.001) whereas that in adult rats still showed a decreased flux from 75.50 +/- 10.12 to 47.77 +/- 5.42 nmol.hr(-1).cm(-2) (P < 0.05). Because oral calcium supplement has been widely used to improve calcium balance in estrogen-deficient animals, the effect of a high-calcium diet (2.0% w/w Ca) was also investigated. The results showed that stimulatory action of long-term prolactin on the transcellular active duodenal calcium transport in both young and adult rats was diminished after being fed a high-calcium diet. The same diet also abolished prolactin-enhanced solvent drag-induced duodenal calcium transport in young and further decreased that in adult AP-grafted ovariectomized rats. We concluded that the solvent drag

  14. Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

    SciTech Connect

    Zhang, Buhao; Xu, Xuhui; Li, Qianyue; Wu, Yumei; Qiu, Jianbei; Yu, Xue

    2014-09-15

    Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R{sup 3+} ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}. The greatly improved LPL performance was observed in Nd{sup 3+} co-doped samples, which indicates that the incorporation of Nd{sup 3+} creates suitable traps for LPL. While co-doping Tm{sup 3+} ions, the intensity of high temperature of thermoluminescence band in CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphors is enhanced for the formation of the most suitable traps which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R{sup 3+} ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} exhibits different read-in/read-out performance as well. - Graphical abstract: OSL emission spectra of Ca{sub 0.995}Al{sub 2}O{sub 4}:0.0025Eu{sup 2+}, 0.0025R{sup 3+} (R=Nd, Dy, Tm) taken under varying stimulation time (0, 25, 50, 75, 100 s). Inset: Blue emission pictures under varying stimulation time. - Highlights: • The LPL and OSL properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} were investigated. • An alternative approach to control the trap depth of CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphor was proposed. • A new oxide ETM phosphor exhibiting intense and stable OSL was explored.

  15. Plasmonic activation of gold nanorods for remote stimulation of calcium signaling and protein expression in HEK 293T cells.

    PubMed

    Sanchez-Rodriguez, Sandra P; Sauer, Jeremy P; Stanley, Sarah A; Qian, Xi; Gottesdiener, Andrew; Friedman, Jeffrey M; Dordick, Jonathan S

    2016-10-01

    Remote activation of specific cells of a heterogeneous population can provide a useful research tool for clinical and therapeutic applications. Here, we demonstrate that photostimulation of gold nanorods (AuNRs) using a tunable near-infrared (NIR) laser at specific longitudinal surface plasmon resonance wavelengths can induce the selective and temporal internalization of calcium in HEK 293T cells. Biotin-PEG-Au nanorods coated with streptavidin Alexa Fluor-633 and biotinylated anti-His antibodies were used to decorate cells genetically modified with His-tagged TRPV1 temperature-sensitive ion channel and AuNRs conjugated to biotinylated RGD peptide were used to decorate integrins in unmodified cells. Plasmonic activation can be stimulated at weak laser power (0.7-4.0 W/cm(2) ) without causing cell damage. Selective activation of TRPV1 channels could be controlled by laser power between 1.0 and 1.5 W/cm(2) . Integrin targeting robustly stimulated calcium signaling due to a dense cellular distribution of nanoparticles. Such an approach represents a functional tool for combinatorial activation of cell signaling in heterogeneous cell populations. Our results suggest that it is possible to induce cell activation via NIR-induced gold nanorod heating through the selective targeting of membrane proteins in unmodified cells to produce calcium signaling and downstream expression of specific genes with significant relevance for both in vitro and therapeutic applications. Biotechnol. Bioeng. 2016;113: 2228-2240. © 2016 Wiley Periodicals, Inc. PMID:27563853

  16. Plasmonic activation of gold nanorods for remote stimulation of calcium signaling and protein expression in HEK 293T cells.

    PubMed

    Sanchez-Rodriguez, Sandra P; Sauer, Jeremy P; Stanley, Sarah A; Qian, Xi; Gottesdiener, Andrew; Friedman, Jeffrey M; Dordick, Jonathan S

    2016-10-01

    Remote activation of specific cells of a heterogeneous population can provide a useful research tool for clinical and therapeutic applications. Here, we demonstrate that photostimulation of gold nanorods (AuNRs) using a tunable near-infrared (NIR) laser at specific longitudinal surface plasmon resonance wavelengths can induce the selective and temporal internalization of calcium in HEK 293T cells. Biotin-PEG-Au nanorods coated with streptavidin Alexa Fluor-633 and biotinylated anti-His antibodies were used to decorate cells genetically modified with His-tagged TRPV1 temperature-sensitive ion channel and AuNRs conjugated to biotinylated RGD peptide were used to decorate integrins in unmodified cells. Plasmonic activation can be stimulated at weak laser power (0.7-4.0 W/cm(2) ) without causing cell damage. Selective activation of TRPV1 channels could be controlled by laser power between 1.0 and 1.5 W/cm(2) . Integrin targeting robustly stimulated calcium signaling due to a dense cellular distribution of nanoparticles. Such an approach represents a functional tool for combinatorial activation of cell signaling in heterogeneous cell populations. Our results suggest that it is possible to induce cell activation via NIR-induced gold nanorod heating through the selective targeting of membrane proteins in unmodified cells to produce calcium signaling and downstream expression of specific genes with significant relevance for both in vitro and therapeutic applications. Biotechnol. Bioeng. 2016;113: 2228-2240. © 2016 Wiley Periodicals, Inc.

  17. Genipin stimulates glucose transport in C2C12 myotubes via an IRS-1 and calcium-dependent mechanism.

    PubMed

    Ma, Chan-Juan; Nie, Ai-Fang; Zhang, Zhi-Jian; Zhang, Zhi-Guo; Du, Li; Li, Xiao-Ying; Ning, Guang

    2013-03-01

    Genipin, a compound derived from Gardenia jasminoides Ellis fruits, has been used over the years in traditional Chinese medicine to treat symptoms of type 2 diabetes. However, the molecular basis for its antidiabetic effect has not been fully revealed. In this study, we investigated the effects of genipin on glucose uptake and signaling pathways in C(2)C(12) myotubes. Our study demonstrates that genipin stimulated glucose uptake in a time- and dose-dependent manner. The maximal effect was achieved at 2 h with a concentration of 10 μM. In myotubes, genipin promoted glucose transporter 4 (GLUT4) translocation to the cell surface, which was observed by analyzing their distribution in subcellular membrane fraction, and increased the phosphorylation of insulin receptor substrate-1 (IRS-1), AKT, and GSK3β. Meanwhile, genipin increased ATP levels, closed K(ATP) channels, and then increased the concentration of calcium in the cytoplasm in C(2)C(12) myotubes. Genipin-stimulated glucose uptake could be blocked by both the PI3-K inhibitor wortmannin and calcium chelator EGTA. Moreover, genipin increases the level of reactive oxygen species and ATP in C(2)C(12) myotubes. These results suggest that genipin activates IRS-1, PI3-K, and downstream signaling pathway and increases concentrations of calcium, resulting in GLUT4 translocation and glucose uptake increase in C(2)C(12) myotubes. PMID:23257267

  18. Mechanics regulates ATP-stimulated collective calcium response in fibroblast cells

    PubMed Central

    Lembong, Josephine; Sabass, Benedikt; Sun, Bo; Rogers, Matthew E.; Stone, Howard A.

    2015-01-01

    Cells constantly sense their chemical and mechanical environments. We study the effect of mechanics on the ATP-induced collective calcium response of fibroblast cells in experiments that mimic various tissue environments. We find that closely packed two-dimensional cell cultures on a soft polyacrylamide gel (Young's modulus E = 690 Pa) contain more cells exhibiting calcium oscillations than cultures on a rigid substrate (E = 36 000 Pa). Calcium responses of cells on soft substrates show a slower decay of calcium level relative to those on rigid substrates. Actin enhancement and disruption experiments for the cell cultures allow us to conclude that actin filaments determine the collective Ca2+ oscillatory behaviour in the culture. Inhibition of gap junctions results in a decrease of the oscillation period and reduced correlation of calcium responses, which suggests additional complexity of signalling upon cell–cell contact. Moreover, the frequency of calcium oscillations is independent of the rigidity of the substrate but depends on ATP concentration. We compare our results with those from similar experiments on individual cells. Overall, our observations show that collective chemical signalling in cell cultures via calcium depends critically on the mechanical environment. PMID:26063818

  19. SIMULTANEOUS CONTROL OF HGO, SO2, AND NOX BY NOVEL OXIDIZED CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of an investigation of two classes of calcium (Ca)-based sorbents (hydrated limes and silicate compounds). (NOTE: Efforts to develop multipollutant control strategies have demonstrated that adding certain oxidants to different classes of Ca-based sorbents...

  20. SIMULTANEOUS CONTROL OF HG(0), SO2, AND NOX BY NOVEL OXIDIZED CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of an investigation of two classes of calcium (Ca)-based sorbents (hydrated limes and silicate compounds). {NOTE: Efforts to develop multipollutant control strategies have demonstrated that adding certain oxidants to different classes of Ca-based sorbents ...

  1. Growth Inhibition and Stimulation of Shewanella oneidensis MR-1 by Surfactants and Calcium Polysulfide

    SciTech Connect

    Bailey, Kathryn L.; Tilton, Fred A.; Jansik, Danielle P.; Ergas, Sarina J.; Marshall, Matthew J.; Miracle, Ann L.; Wellman, Dawn M.

    2012-06-14

    Foam delivery technology (FDT) uses surfactant based foam to immobilize subsurface contaminants in situ. Where traditional approaches are impractical, FDT has the potential to overcome many of the technical challenges facing the remediation of contaminated deep vadose zone environments. However, little is known about the effects these reactive chemicals may have on microorganisms inhabiting the contaminated subsurface. In addition, there are currently no standard assays to assess microbial responses to subsurface remedial treatments while these agents are under development. The objective of this study was to develop a rapid laboratory assay to assess the potential growth inhibition and/or stimulation of microorganisms following exposure to candidate FDT components. Calcium polysulfide (CPS) and several surfactants (i.e. sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), cocamidopropyl betaine (CAPB) and NINOL40-CO) have diverse chemistries and are candidate components of FDT. Shewanella oneidensis MR-1 cultures were exposed to a range of concentrations of these chemicals to determine the minimum bactericidal concentration (MBC) and the growth and viability potential of these components. Concentrations of SDS higher than 700 {micro}M were toxic to S. oneidensis MR-1 growth over the course of four days of exposure. The relative acute toxicity order for these compounds was SDS>>CPS>>NINOL40-CO>SLES-CAPB. Dose dependent growth decreases (20 to 100 mM) were observed in the CAPB and SLES treated cultures and both CPS and NINOL 40-CO were toxic at all concentrations tested (1.45 to 7.25 mM CPS). Both SLES (20 to 100 mM) and SDS at lower concentrations (20 to 500 {micro}M) were stimulatory to S. oneidensis MR-1 indicating a capacity to be used as a carbon source. These studies also identified potentially key component characteristics, such as precipitate formation and oxygen availability, which may prove valuable in assessing the response of subsurface

  2. Reduced graphene oxide-coated hydroxyapatite composites stimulate spontaneous osteogenic differentiation of human mesenchymal stem cells

    NASA Astrophysics Data System (ADS)

    Lee, Jong Ho; Shin, Yong Cheol; Jin, Oh Seong; Kang, Seok Hee; Hwang, Yu-Shik; Park, Jong-Chul; Hong, Suck Won; Han, Dong-Wook

    2015-07-01

    Human mesenchymal stem cells (hMSCs) have great potential as cell sources for bone tissue engineering and regeneration, but the control and induction of their specific differentiation into bone cells remain challenging. Graphene-based nanomaterials are considered attractive candidates for biomedical applications such as scaffolds in tissue engineering, substrates for SC differentiation and components of implantable devices, due to their biocompatible and bioactive properties. Despite the potential biomedical applications of graphene and its derivatives, only limited information is available regarding their osteogenic activity. This study concentrates upon the effects of reduced graphene oxide (rGO)-coated hydroxyapatite (HAp) composites on osteogenic differentiation of hMSCs. The average particle sizes of HAp and rGO were 1270 +/- 476 nm and 438 +/- 180 nm, respectively. When coated on HAp particulates, rGO synergistically enhanced spontaneous osteogenic differentiation of hMSCs, without hampering their proliferation. This result was confirmed by determining alkaline phosphatase activity and mineralization of calcium and phosphate as early and late stage markers of osteogenic differentiation. It is suggested that rGO-coated HAp composites can be effectively utilized as dental and orthopedic bone fillers since these graphene-based particulate materials have potent effects on stimulating the spontaneous differentiation of MSCs and show superior bioactivity and osteoinductive potential.Human mesenchymal stem cells (hMSCs) have great potential as cell sources for bone tissue engineering and regeneration, but the control and induction of their specific differentiation into bone cells remain challenging. Graphene-based nanomaterials are considered attractive candidates for biomedical applications such as scaffolds in tissue engineering, substrates for SC differentiation and components of implantable devices, due to their biocompatible and bioactive properties. Despite

  3. Biological water-oxidizing complex: a nano-sized manganese-calcium oxide in a protein environment.

    PubMed

    Najafpour, Mohammad Mahdi; Moghaddam, Atefeh Nemati; Yang, Young Nam; Aro, Eva-Mari; Carpentier, Robert; Eaton-Rye, Julian J; Lee, Choon-Hwan; Allakhverdiev, Suleyman I

    2012-10-01

    The resolution of Photosystem II (PS II) crystals has been improved using isolated PS II from the thermophilic cyanobacterium Thermosynechococcus vulcanus. The new 1.9 Å resolution data have provided detailed information on the structure of the water-oxidizing complex (Umena et al. Nature 473: 55-61, 2011). The atomic level structure of the manganese-calcium cluster is important for understanding the mechanism of water oxidation and to design an efficient catalyst for water oxidation in artificial photosynthetic systems. Here, we have briefly reviewed our knowledge of the structure and function of the cluster.

  4. Stimulation-dependent recruitment of cytosolic phospholipase A2-alpha to EA.hy.926 endothelial cell membranes leads to calcium-independent association.

    PubMed

    Grewal, Seema; Smith, Jennifer; Ponnambalam, Sreenivasan; Walker, John

    2004-01-01

    Cytosolic phospholipase A2-alpha (cPLA2-alpha) is a calcium-activated enzyme involved in agonist-induced arachidonic acid release. In endothelial cells, free arachidonic acid is predominantly converted into prostacyclin, a potent vasodilator and inhibitor of platelet activation. As the rate-limiting step in prostacyclin production is the generation of free arachidonic acid by cPLA2-alpha, this enzyme has become an attractive pharmacological target and the focus of many studies. Following stimulation with calcium-mobilizing agonists, cPLA2-alpha translocates to intracellular phospholipid membranes via its C2 domain. In this study, the calcium-induced association of cPLA2-alpha with EA.hy.926 endothelial cell membranes was investigated. Subcellular fractionation and immunofluorescence studies showed that following stimulation with histamine, thrombin or the calcium ionophore A23187, cPLA2-alpha relocated to intracellular membranes. Treatment of A23187-stimulated cells with EGTA or BAPTA-AM demonstrated that a substantial pool of cPLA2-alpha remained associated with membrane fractions in a calcium-independent manner. Furthermore, immunofluorescence microscopy studies revealed that cells stimulated for periods of greater than 10 min showed a high proportion of calcium-independent membrane-associated cPLA2-alpha. Calcium-independent membrane association of cPLA2-alpha was not due to hydrophobic or cytoskeletal interactions. Finally, the recombinant C2 domain of cPLA2-alpha exhibited calcium-independent membrane binding to membranes isolated from A23187-stimulated cells but not those isolated from nonstimulated cells. These findings suggest that novel mechanisms involving accessory proteins at the target membrane play a role in the regulation of cPLA2-alpha. Such regulatory associations could enable the cell to discriminate between the varying levels of cytosolic calcium induced by different stimuli.

  5. Cytoplasmic calcium mediates oxidative damage in an excitotoxic /energetic deficit synergic model in rats.

    PubMed

    Pérez-De La Cruz, Verónica; Konigsberg, Mina; Pedraza-Chaverri, José; Herrera-Mundo, Nieves; Díaz-Muñoz, Mauricio; Morán, Julio; Fortoul-van der Goes, Teresa; Rondán-Zárate, Adrián; Maldonado, Perla D; Ali, Syed F; Santamaría, Abel

    2008-03-01

    Excessive calcium is responsible for triggering different potentially fatal metabolic pathways during neurodegeneration. In this study, we evaluated the role of calcium on the oxidative damage produced in an in vitro combined model of excitotoxicity/energy deficit produced by the co-administration of quinolinate and 3-nitropropionate to brain synaptosomal membranes. Synaptosomal fractions were incubated in the presence of subtoxic concentrations of these agents (21 and 166 microm, respectively). In order further to characterize possible toxic mechanisms involved in oxidative damage in this experimental paradigm, agents with different properties - dizocilpine, acetyl L-carnitine, iron porphyrinate and S-allylcysteine - were tested at increasing concentrations (10-1000 microm). Lipid peroxidation was assessed by the formation of thiobarbituric acid-reactive substances. For confirmatory purposes, additional fractions were incubated in parallel in the presence of the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM). Under physiological conditions of extracellular calcium availability, synaptomes exposed to both toxins displayed an increased lipoperoxidation (76% above controls), and this effect was partially attenuated by the tested agents as follows: dizocilpine = iron porphyrinate > acetyl L-carnitine > S-allylcysteine. When the incubation medium was deprived of calcium, the lipoperoxidative effect achieved in this experimental paradigm was still high (49% above the control), and the order of attenuation was: iron porphyrinate > S-allylcysteine > acetyl L-carnitine > dizocilpine. BAPTA-AM was effective in preventing the pro-oxidant action of both toxins, promoting even lower peroxidative levels than those quantified under basal conditions. Our results suggest that the lipid peroxidation induced in synaptosomal fractions by quinolinate plus 3-nitropropionate is largely dependent on the cytoplasmic

  6. Formation of calcium in the products of iron oxide-aluminum thermite combustion in air

    NASA Astrophysics Data System (ADS)

    Gromov, A. A.; Gromov, A. M.; Popenko, E. M.; Sergienko, A. V.; Sabinskaya, O. G.; Raab, B.; Teipel, U.

    2016-10-01

    The composition of condensed products resulting from the combustion of thermite mixtures (Al + Fe2O3) in air is studied by precise methods. It is shown that during combustion, calcium is formed and stabilized in amounts of maximal 0.55 wt %, while is missing from reactants of 99.7 wt % purity. To explain this, it is hypothesized that a low-energy nuclear reaction takes place alongside the reactions of aluminum oxidation and nitridation, resulting in the formation of calcium (Kervran-Bolotov reaction).

  7. Reference values of serum calcitonin with calcium stimulation tests by electrochemiluminescence immunoassay before/after total thyroidectomy in Japanese patients with thyroid diseases other than medullary thyroid carcinoma.

    PubMed

    Kihara, Minoru; Miyauchi, Akira; Kudo, Takumi; Hirokawa, Mitsuyoshi; Miya, Akihiro

    2016-07-30

    Calcitonin is a very sensitive tumor marker of medullary thyroid carcinoma (MTC). MTC patients usually have very high values of serum calcitonin that can be used to diagnose the disease. To improve the diagnostic sensitivity in family members with small MTCs and to evaluate the postoperative biochemical cure status, a calcium stimulation test is widely used. Serum calcitonin has been measured using several methods, but in Japan, only an electrochemiluminescence immunoassay (ECLIA) is currently performed to determine serum calcitonin. Reference values for the calcium stimulation test using an ECLIA have not been reported. Here we conducted a calcium stimulation tests in 26 patients without MTC before and after total thyroidectomy. Preoperatively, the basal calcitonin values of all patients were within normal limits and increased to a mean of 14.4 pg/mL after calcium stimulation. We transformed the peak values before total thyroidectomy to a logarithmic distribution and calculated the normalized mean ± 1.96× standard deviation; the reference upper limit was thus expressed. In the female patients with non-MTC, the reference upper limit was 67.6 pg/mL. In all patients, the calcium stimulation test results after total thyroidectomy showed undetectable basal and stimulated calcitonin values (<0.5 pg/mL). This is the first study to determine reference values to be used for the calcium stimulation test along with an ECLIA in non-MTC patients. We propose that female patients are regarded as biochemically cured or normal when the stimulated calcitonin values by ECLIA are <67.6 pg/mL before surgery and <0.5 pg/mL after total thyroidectomy. PMID:27097651

  8. Bimatoprost and prostaglandin F(2 alpha) selectively stimulate intracellular calcium signaling in different cat iris sphincter cells.

    PubMed

    Spada, Clayton S; Krauss, Achim H-P; Woodward, David F; Chen, June; Protzman, Charles E; Nieves, Amelia L; Wheeler, Larry A; Scott, David F; Sachs, George

    2005-01-01

    Bimatoprost is a synthetic analog of prostaglandin F(2 alpha) ethanolamide (prostamide F(2 alpha)), and shares a pharmacological profile consistent with that of the prostamides. Like prostaglandin F(2 alpha) carboxylic acid, bimatoprost potently lowers intraocular pressure in dogs, primates and humans. In order to distinguish its mechanism of action from prostaglandin F(2 alpha), fluorescence confocal microscopy was used to examine the effects of bimatoprost, prostaglandin F(2 alpha) and 17-phenyl prostaglandin F(2 alpha) on calcium signaling in resident cells of digested cat iris sphincter, a tissue which exhibits contractile responses to both agonists. Constant superfusion conditions obviated effective conversion of bimatoprost. Serial challenge with 100 nM bimatoprost and prostaglandin F(2 alpha) consistently evoked responses in different cells within the same tissue preparation, whereas prostaglandin F(2 alpha) and 17-phenyl prostaglandin F(2 alpha) elicited signaling responses in the same cells. Bimatoprost-sensitive cells were consistently re-stimulated with bimatoprost only, and prostaglandin F(2 alpha) sensitive cells could only be re-stimulated with prostaglandin F(2 alpha). The selective stimulation of different cells in the same cat iris sphincter preparation by bimatoprost and prostaglandin F(2 alpha), along with the complete absence of observed instances in which the same cells respond to both agonists, strongly suggests the involvement of distinct receptors for prostaglandin F(2 alpha) and bimatoprost. Further, prostaglandin F(2 alpha) but not bimatoprost potently stimulated calcium signaling in isolated human embryonic kidney cells stably transfected with the feline- and human-prostaglandin F(2 alpha) FP-receptor and in human dermal fibroblast cells, and only prostaglandin F(2 alpha) competed with radioligand binding in HEK-feFP cells. These studies provide further evidence for the existence of a bimatoprost-sensitive receptor that is distinct from

  9. Stimulants

    MedlinePlus

    Stimulants are drugs that increase your heart rate, breathing rate, and brain function. Some stimulants affect only a specific organ, such as the heart, lungs, brain, or nervous system. Epinephrine is a stimulant. It ...

  10. Mechanisms of pyrethroid insecticide-induced stimulation of calcium influx in neocortical neurons

    EPA Science Inventory

    Pyrethroid insecticides bind to voltage-gated sodium channels (VGSCs) and modify their gating kinetics, thereby disrupting neuronal function. Pyrethroids have also been reported to alter the function of other channel types, including activation of voltage-gated Ca2+ calcium chann...

  11. Construction and use of a zebrafish heart voltage and calcium optical mapping system, with integrated electrocardiogram and programmable electrical stimulation.

    PubMed

    Lin, Eric; Craig, Calvin; Lamothe, Marcel; Sarunic, Marinko V; Beg, Mirza Faisal; Tibbits, Glen F

    2015-05-01

    Zebrafish are increasingly being used as a model of vertebrate cardiology due to mammalian-like cardiac properties in many respects. The size and fecundity of zebrafish make them suitable for large-scale genetic and pharmacological screening. In larger mammalian hearts, optical mapping is often used to investigate the interplay between voltage and calcium dynamics and to investigate their respective roles in arrhythmogenesis. This report outlines the construction of an optical mapping system for use with zebrafish hearts, using the voltage-sensitive dye RH 237 and the calcium indicator dye Rhod-2 using two industrial-level CCD cameras. With the use of economical cameras and a common 532-nm diode laser for excitation, the rate dependence of voltage and calcium dynamics within the atrial and ventricular compartments can be simultaneously determined. At 140 beats/min, the atrial action potential duration was 36 ms and the transient duration was 53 ms. With the use of a programmable electrical stimulator, a shallow rate dependence of 3 and 4 ms per 100 beats/min was observed, respectively. In the ventricle the action potential duration was 109 ms and the transient duration was 124 ms, with a steeper rate dependence of 12 and 16 ms per 100 beats/min. Synchronous electrocardiograms and optical mapping recordings were recorded, in which the P-wave aligns with the atrial voltage peak and R-wave aligns with the ventricular peak. A simple optical pathway and imaging chamber are detailed along with schematics for the in-house construction of the electrocardiogram amplifier and electrical stimulator. Laboratory procedures necessary for zebrafish heart isolation, cannulation, and loading are also presented.

  12. Construction and use of a zebrafish heart voltage and calcium optical mapping system, with integrated electrocardiogram and programmable electrical stimulation

    PubMed Central

    Lin, Eric; Craig, Calvin; Lamothe, Marcel; Sarunic, Marinko V.; Beg, Mirza Faisal

    2015-01-01

    Zebrafish are increasingly being used as a model of vertebrate cardiology due to mammalian-like cardiac properties in many respects. The size and fecundity of zebrafish make them suitable for large-scale genetic and pharmacological screening. In larger mammalian hearts, optical mapping is often used to investigate the interplay between voltage and calcium dynamics and to investigate their respective roles in arrhythmogenesis. This report outlines the construction of an optical mapping system for use with zebrafish hearts, using the voltage-sensitive dye RH 237 and the calcium indicator dye Rhod-2 using two industrial-level CCD cameras. With the use of economical cameras and a common 532-nm diode laser for excitation, the rate dependence of voltage and calcium dynamics within the atrial and ventricular compartments can be simultaneously determined. At 140 beats/min, the atrial action potential duration was 36 ms and the transient duration was 53 ms. With the use of a programmable electrical stimulator, a shallow rate dependence of 3 and 4 ms per 100 beats/min was observed, respectively. In the ventricle the action potential duration was 109 ms and the transient duration was 124 ms, with a steeper rate dependence of 12 and 16 ms per 100 beats/min. Synchronous electrocardiograms and optical mapping recordings were recorded, in which the P-wave aligns with the atrial voltage peak and R-wave aligns with the ventricular peak. A simple optical pathway and imaging chamber are detailed along with schematics for the in-house construction of the electrocardiogram amplifier and electrical stimulator. Laboratory procedures necessary for zebrafish heart isolation, cannulation, and loading are also presented. PMID:25740339

  13. Calcium-sensitive MRI contrast agents based on superparamagnetic iron oxide nanoparticles and calmodulin.

    PubMed

    Atanasijevic, Tatjana; Shusteff, Maxim; Fam, Peter; Jasanoff, Alan

    2006-10-01

    We describe a family of calcium indicators for magnetic resonance imaging (MRI), formed by combining a powerful iron oxide nanoparticle-based contrast mechanism with the versatile calcium-sensing protein calmodulin and its targets. Calcium-dependent protein-protein interactions drive particle clustering and produce up to 5-fold changes in T2 relaxivity, an indication of the sensors' potency. A variant based on conjugates of wild-type calmodulin and the peptide M13 reports concentration changes near 1 microM Ca(2+), suitable for detection of elevated intracellular calcium levels. The midpoint and cooperativity of the response can be tuned by mutating the protein domains that actuate the sensor. Robust MRI signal changes are achieved even at nanomolar particle concentrations (<1 microM in calmodulin) that are unlikely to buffer calcium levels. When combined with technologies for cellular delivery of nanoparticulate agents, these sensors and their derivatives may be useful for functional molecular imaging of biological signaling networks in live, opaque specimens.

  14. Calcium-sensitive MRI contrast agents based on superparamagnetic iron oxide nanoparticles and calmodulin

    PubMed Central

    Atanasijevic, Tatjana; Shusteff, Maxim; Fam, Peter; Jasanoff, Alan

    2006-01-01

    We describe a family of calcium indicators for magnetic resonance imaging (MRI), formed by combining a powerful iron oxide nanoparticle-based contrast mechanism with the versatile calcium-sensing protein calmodulin and its targets. Calcium-dependent protein–protein interactions drive particle clustering and produce up to 5-fold changes in T2 relaxivity, an indication of the sensors' potency. A variant based on conjugates of wild-type calmodulin and the peptide M13 reports concentration changes near 1 μM Ca2+, suitable for detection of elevated intracellular calcium levels. The midpoint and cooperativity of the response can be tuned by mutating the protein domains that actuate the sensor. Robust MRI signal changes are achieved even at nanomolar particle concentrations (<1 μM in calmodulin) that are unlikely to buffer calcium levels. When combined with technologies for cellular delivery of nanoparticulate agents, these sensors and their derivatives may be useful for functional molecular imaging of biological signaling networks in live, opaque specimens. PMID:17003117

  15. Characterization of calcium containing plasma electrolytic oxidation coatings on AM50 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Srinivasan, P. Bala; Liang, J.; Blawert, C.; Störmer, M.; Dietzel, W.

    2010-04-01

    An attempt was made to produce calcium containing plasma electrolytic oxidation (PEO) coatings on AM50 magnesium alloy using an alkaline electrolyte. This study was performed in three alkaline electrolytes containing calcium hydroxide and sodium phosphate with three different mass ratios viz., 1:2.5, 1:5 and 1:7.5. All the three coatings produced were found to contain Ca and P in appreciable amounts. The concentration of P was found to be higher in the coatings obtained in the electrolytes with higher concentration of phosphate ions. Even though all the three coatings were found to be constituted with magnesium oxide and magnesium phosphate phases, X-ray diffraction analyses revealed that the phase composition was influenced by the phosphate ion concentration/conductivity of the electrolyte. Further, the PEO coating obtained in the 1:7.5 ratio electrolyte was found to contain di-calcium phosphate (monetite) and calcium peroxide phases, which were absent in the other two coatings. Potentiodynamic polarization studies performed in 0.1 M NaCl solution showed that the coatings obtained from the 1:5 ratio electrolyte possessed a superior corrosion resistance, which is attributed to the combined effect of thickness, compactness and phase/chemical composition of this coating.

  16. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

    NASA Astrophysics Data System (ADS)

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V.; Marlow, Jeffrey J.; Orphan, Victoria J.

    2014-10-01

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate-methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling.

  17. Histamine stimulates calcium-mediated protein phosphorylation in a colonic epithelial cell line.

    PubMed

    Cohn, J A; Dougherty, N C; King, W F

    1989-12-15

    Protein phosphorylation responses in intact enterocytes were examined by stimulating 32Pi-labeled T84 cell monolayers with histamine and resolving proteins by two-dimensional gel electrophoresis. Histamine increases 32P-incorporation into two acidic proteins of Mr 83,000 and of Mr 29,000, designated p83 and p29. Labeling of p83 and p29 is also increased in cells exposed to ionomycin, but not in cells exposed to vasoactive intestinal peptide under conditions resulting in cAMP-mediated secretion and cAMP-stimulated protein phosphorylation. When T84 cell fractions are incubated with [gamma-32P]ATP, labeling of p83 is stimulated by Ca++, but not by cAMP. Thus, histamine stimulates Ca++-mediated protein phosphorylation during the regulation of Cl- secretion.

  18. High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor.

    PubMed

    Dou, Binlin; Song, Yongchen; Liu, Yingguang; Feng, Cong

    2010-11-15

    The gas-solid reaction and breakthrough curve of CO(2) capture using calcium oxide sorbent at high temperature in a fixed-bed reactor are of great importance, and being influenced by a number of factors makes the characterization and prediction of these a difficult problem. In this study, the operating parameters on reaction between solid sorbent and CO(2) gas at high temperature were investigated. The results of the breakthrough curves showed that calcium oxide sorbent in the fixed-bed reactor was capable of reducing the CO(2) level to near zero level with the steam of 10 vol%, and the sorbent in CaO mixed with MgO of 40 wt% had extremely low capacity for CO(2) capture at 550°C. Calcium oxide sorbent after reaction can be easily regenerated at 900°C by pure N(2) flow. The experimental data were analyzed by shrinking core model, and the results showed reaction rates of both fresh and regeneration sorbents with CO(2) were controlled by a combination of the surface chemical reaction and diffusion of product layer.

  19. Intestinal calcium absorption in rats is stimulated by dietary lactulose and other resistant sugars.

    PubMed

    Brommage, R; Binacua, C; Antille, S; Carrié, A L

    1993-12-01

    Lactulose is a disaccharide analogue of lactose that is resistant to metabolism in the small intestine but not in the large intestine. The effects of lactulose and other sugars on intestinal Ca absorption were determined from the decrease in the 47Ca:47 Sc ratio between diet and feces after feeding male rats diets containing these sugars during a single night. Dietary lactulose was more potent than lactose in stimulating Ca absorption and was effective between 5 and 38 wk of age. The component sugars of lactulose, galactose and fructose, did not influence Ca absorption when provided together at concentrations equimolar to that of lactulose. The stimulation of Ca absorption by dietary lactulose increased as dietary Ca concentration was raised and was not influenced by prior injections of calcitriol. Lactulose must be present in the same meal as Ca to stimulate Ca absorption, but this stimulation was lost if the rats were fed lactulose continuously for 2 or 7 d prior to the test diet. Other sugars thought to be poorly absorbed in the small intestine (xylitol, lactobionate, arabinose, raffinose, pyroglutamate, sorbitol, gluconate and raftilose) stimulated Ca absorption to an identical extent as lactulose. Cecectomy did not influence the enhancement of Ca absorption by lactulose. These results indicate that sugars resistant to metabolism and absorption in the small intestine but not the large intestine stimulate Ca absorption in the small intestine.

  20. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    NASA Astrophysics Data System (ADS)

    Rastsvetaeva, R. K.; Aksenov, S. M.; Verin, I. A.

    2010-07-01

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) Å, b = 17.1823(4) Å, c = 23.5718(5) Å, β = 90°, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with | F| > 7σ( F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula ( Z = 4) is Ca2Mg{2/IV}Fe{2/(2+)IV}[Al{14/VI}O31(OH)][Al{2/IV}O][AlIV]ALIV(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe2+ tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  1. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    SciTech Connect

    Rastsvetaeva, R. K. Aksenov, S. M.; Verin, I. A.

    2010-07-15

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) A, b = 17.1823(4) A, c = 23.5718(5) A, {beta} = 90{sup o}, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with vertical bar F vertical bar > 7{sigma}(F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula (Z = 4) is Ca{sub 2}Mg{sub 2}{sup IV}Fe{sub 2}{sup (2+)IV}[Al{sub 14}{sup VI}O{sub 31}(OH)][Al{sub 2}{sup IV}O][Al{sup IV}]AL{sup IV}(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe{sup 2+} tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  2. Staphylococcal exotoxins stimulate nitric oxide-dependent murine macrophage tumoricidal activity.

    PubMed Central

    Fast, D J; Shannon, B J; Herriott, M J; Kennedy, M J; Rummage, J A; Leu, R W

    1991-01-01

    The staphylococcal exotoxins toxic shock syndrome toxin 1 (TSST-1) and enterotoxin B were tested for their ability to stimulate murine peritoneal macrophages (PM) for tumoricidal activity. Both toxins were found to stimulate oil-elicited, gamma interferon-primed PM monolayers to kill nonadherent P815 tumor targets. The mechanism of killing of toxin-stimulated tumoricidal activity involved the production of nitric oxide, as nitrite could be demonstrated in culture fluids, and NG-monomethyl-L-arginine, an inhibitor of nitric oxide production, abrogated toxin-stimulated tumoricidal activity. TSST-1 stimulated the secretion of tumor necrosis factor by PM monolayers in the presence and absence of gamma interferon. The mechanism of toxin-stimulated tumoricidal activity was also determined to be independent of the production of reactive oxygen intermediates in that TSST-1 failed to stimulate H2O2 production by PM. These results demonstrate that the staphylococcal exotoxins are capable of stimulating macrophage production of nitric oxide for tumor cytotoxicity and suggest that the nitric oxide thus produced may subsequently play a role in the pathogenesis of the diseases caused by these toxins. PMID:1908828

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

    SciTech Connect

    Wenling Hsieh; Sze, Heven )

    1991-05-01

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

  4. Calcium puffs are generic InsP(3)-activated elementary calcium signals and are downregulated by prolonged hormonal stimulation to inhibit cellular calcium responses.

    PubMed

    Tovey, S C; de Smet, P; Lipp, P; Thomas, D; Young, K W; Missiaen, L; De Smedt, H; Parys, J B; Berridge, M J; Thuring, J; Holmes, A; Bootman, M D

    2001-11-01

    Elementary Ca(2+) signals, such as "Ca(2+) puffs", which arise from the activation of inositol 1,4,5-trisphosphate receptors, are building blocks for local and global Ca(2+) signalling. We characterized Ca(2+) puffs in six cell types that expressed differing ratios of the three inositol 1,4,5-trisphosphate receptor isoforms. The amplitudes, spatial spreads and kinetics of the events were similar in each of the cell types. The resemblance of Ca(2+) puffs in these cell types suggests that they are a generic elementary Ca(2+) signal and, furthermore, that the different inositol 1,4,5-trisphosphate isoforms are functionally redundant at the level of subcellular Ca(2+) signalling. Hormonal stimulation of SH-SY5Y neuroblastoma cells and HeLa cells for several hours downregulated inositol 1,4,5-trisphosphate expression and concomitantly altered the properties of the Ca(2+) puffs. The amplitude and duration of Ca(2+) puffs were substantially reduced. In addition, the number of Ca(2+) puff sites active during the onset of a Ca(2+) wave declined. The consequence of the changes in Ca(2+) puff properties was that cells displayed a lower propensity to trigger regenerative Ca(2+) waves. Therefore, Ca(2+) puffs underlie inositol 1,4,5-trisphosphate signalling in diverse cell types and are focal points for regulation of cellular responses.

  5. Purifications of calcium carbonate and molybdenum oxide powders for neutrinoless double beta decay experiment, AMoRE

    SciTech Connect

    Park, HyangKyu

    2015-08-17

    The AMoRE (Advanced Mo based Rare process Experiment) collaboration is going to use calcium molybdate crystals to search for neutrinoless double beta decay of {sup 100}Mo isotope. In order to make the crystal, we use calcium carbonate and molybdenum oxide powders as raw materials. Therefore it is highly necessary to reduce potential sources for radioactive backgrounds such as U and Th in the powders. In this talk, we will present our studies for purification of calcium carbonate and molybdenum oxide powders.

  6. Collagen Stimulators: Poly-L-Lactic Acid and Calcium Hydroxyl Apatite.

    PubMed

    Breithaupt, Andrew; Fitzgerald, Rebecca

    2015-11-01

    Over the last decade, many studies of the structural changes observed in the aging face (in bone, fat pads, facial ligaments, muscle, skin) have increased our understanding that facial rejuvenation is more complex and nuanced than simply filling lines and folds or cutting and lifting soft tissue and skin. This, in addition to the many new products introduced to the marketplace over the same period, has fueled the evolution of panfacial rejuvenation and restoration using fillers. This article discusses current techniques used with calcium hydroxylapatite and poly-l-lactic acid to safely and effectively address changes observed in the aging face. PMID:26505542

  7. Collagen Stimulators: Poly-L-Lactic Acid and Calcium Hydroxyl Apatite.

    PubMed

    Breithaupt, Andrew; Fitzgerald, Rebecca

    2015-11-01

    Over the last decade, many studies of the structural changes observed in the aging face (in bone, fat pads, facial ligaments, muscle, skin) have increased our understanding that facial rejuvenation is more complex and nuanced than simply filling lines and folds or cutting and lifting soft tissue and skin. This, in addition to the many new products introduced to the marketplace over the same period, has fueled the evolution of panfacial rejuvenation and restoration using fillers. This article discusses current techniques used with calcium hydroxylapatite and poly-l-lactic acid to safely and effectively address changes observed in the aging face.

  8. Activation of TRPV2 and BKCa channels by the LL-37 enantiomers stimulates calcium entry and migration of cancer cells

    PubMed Central

    Guéguinou, Maxime; Chourpa, Igor; Fromont, Gaëlle; Bouchet, Ana Maria; Burlaud-Gaillard, Julien; Potier-Cartereau, Marie; Roger, Sébastien; Aucagne, Vincent; Chevalier, Stéphan; Vandier, Christophe

    2016-01-01

    Expression of the antimicrobial peptide hCAP18/LL-37 is associated to malignancy in various cancer forms, stimulating cell migration and metastasis. We report that LL-37 induces migration of three cancer cell lines by activating the TRPV2 calcium-permeable channel and recruiting it to pseudopodia through activation of the PI3K/AKT pathway. Ca2+ entry through TRPV2 cooperated with a K+ efflux through the BKCa channel. In a panel of human breast tumors, the expression of TRPV2 and LL-37 was found to be positively correlated. The D-enantiomer of LL-37 showed identical effects as the L-peptide, suggesting that no binding to a specific receptor was involved. LL-37 attached to caveolae and pseudopodia membranes and decreased membrane fluidity, suggesting that a modification of the physical properties of the lipid membrane bilayer was the underlying mechanism of its effects. PMID:26993604

  9. Biocompatibility of Portland Cement Modified with Titanium Oxide and Calcium Chloride in a Rat Model

    PubMed Central

    Hoshyari, Narjes; Labbaf, Hossein; Jalayer Naderi, Nooshin; Kazemi, Ali; Bastami, Farshid; Koopaei, Maryam

    2016-01-01

    Introduction: The aim of the present study was to evaluate the biocompatibility of two modified formulations of Portland cement (PC) mixed with either titanium oxide or both titanium oxide and calcium chloride. Methods and Materials: Polyethylene tubes were filled with modified PCs or Angelus MTA as the control; the tubes were then implanted in 28 Wistar rats subcutaneously. One tube was left empty as a negative control in each rat. Histologic samples were taken after 7, 15, 30 and 60 days. Sections were assessed histologically for inflammatory responses and presence of fibrous capsule and granulation tissue formation. Data were analyzed using the Fisher’s exact and Kruskal-Wallis tests. Result: PC mixed with titanium oxide showed the highest mean scores of inflammation compared with others. There was no statistically significant difference in the mean inflammatory grades between all groups in each of the understudy time intervals. Conclusion: The results showed favorable biocompatibility of these modified PC mixed with calcium chloride and titanium oxide. PMID:27141221

  10. Stimulation of Odontogenesis and Angiogenesis via Bioactive Nanocomposite Calcium Phosphate Cements Through Integrin and VEGF Signaling Pathways.

    PubMed

    Lee, Sang-Im; Lee, Eui-Suk; El-Fiqi, Ahmed; Lee, So-Youn; Eun-Cheol Kim; Kim, Hae-Won

    2016-05-01

    Formulating self-setting calcium phosphate cements (CPCs) with secondary phases particularly in the nanoscale order holds great promise to improve biological properties. Here, we focus on the effect that bioactive glass nanoparticles (BGN) incorporated in CPC compositions can have on the proliferation, odontogenic differentiation, and angiogenic stimulation of stem cells derived from human dental pulp (HDPSCs). These odontogenic and angiogenic events are of special importance in the dentin-pulp regeneration processes. In comparison to pure CPCs, nanocomposite cements exhibit a significantly improved proliferation of HDPSCs, and the improvement is more significant as the BGN content increases. The nanocomposite cements substantially enhance the adhesion of cells, and significantly up-regulate odontogenic differentiation, including alkaline phosphatase (ALP) activity and the expressions of odontogenic genes (sialophosphoprotein, dentin matrix protein I, ALP, osteopontin and osteocalcin). Furthermore, the use of nanocomposite cements result in stimulation of angiogenic gene expression (VEGF, FGF-2, VEGFRs, PECAM-1, and VE-cadherin) and protein production (VEGF, VEGFR-1). The angiogenic stimulation by the HDPSCs significantly affects the endothelial cell behaviors, that is, the endothelial cell migration and the tubular network formation are substantially improved when treated with HDPSC-conditioned medium, particularly with the help of nanocomposite cements. The integrin and VEGF signaling pathways are reasoned for the stimulation of the odontogenesis and angiogenesis of cells, where the nanocomposite cements up-regulate the integrin subsets α1, α2, α3, and β1, and activate the integrin downstream signal pathways, such as p-FAK, p-Akt, p-paxillin, JNK, EK, and NF-κB, as well as other nuclear transcriptional factors, including CREB, STAT-3, and ELK-1. The current results indicate that the new formulation of the nanocomposite self-setting cements might provide some

  11. Stimulation of Odontogenesis and Angiogenesis via Bioactive Nanocomposite Calcium Phosphate Cements Through Integrin and VEGF Signaling Pathways.

    PubMed

    Lee, Sang-Im; Lee, Eui-Suk; El-Fiqi, Ahmed; Lee, So-Youn; Eun-Cheol Kim; Kim, Hae-Won

    2016-05-01

    Formulating self-setting calcium phosphate cements (CPCs) with secondary phases particularly in the nanoscale order holds great promise to improve biological properties. Here, we focus on the effect that bioactive glass nanoparticles (BGN) incorporated in CPC compositions can have on the proliferation, odontogenic differentiation, and angiogenic stimulation of stem cells derived from human dental pulp (HDPSCs). These odontogenic and angiogenic events are of special importance in the dentin-pulp regeneration processes. In comparison to pure CPCs, nanocomposite cements exhibit a significantly improved proliferation of HDPSCs, and the improvement is more significant as the BGN content increases. The nanocomposite cements substantially enhance the adhesion of cells, and significantly up-regulate odontogenic differentiation, including alkaline phosphatase (ALP) activity and the expressions of odontogenic genes (sialophosphoprotein, dentin matrix protein I, ALP, osteopontin and osteocalcin). Furthermore, the use of nanocomposite cements result in stimulation of angiogenic gene expression (VEGF, FGF-2, VEGFRs, PECAM-1, and VE-cadherin) and protein production (VEGF, VEGFR-1). The angiogenic stimulation by the HDPSCs significantly affects the endothelial cell behaviors, that is, the endothelial cell migration and the tubular network formation are substantially improved when treated with HDPSC-conditioned medium, particularly with the help of nanocomposite cements. The integrin and VEGF signaling pathways are reasoned for the stimulation of the odontogenesis and angiogenesis of cells, where the nanocomposite cements up-regulate the integrin subsets α1, α2, α3, and β1, and activate the integrin downstream signal pathways, such as p-FAK, p-Akt, p-paxillin, JNK, EK, and NF-κB, as well as other nuclear transcriptional factors, including CREB, STAT-3, and ELK-1. The current results indicate that the new formulation of the nanocomposite self-setting cements might provide some

  12. Manganese redistribution by calcium-stimulated vesicle trafficking bypasses the need for P-type ATPase function.

    PubMed

    García-Rodríguez, Néstor; Manzano-López, Javier; Muñoz-Bravo, Miguel; Fernández-García, Elisabet; Muñiz, Manuel; Wellinger, Ralf Erik

    2015-04-10

    Regulation of intracellular ion homeostasis is essential for eukaryotic cell physiology. An example is provided by loss of ATP2C1 function, which leads to skin ulceration, improper keratinocyte adhesion, and cancer formation in Hailey-Hailey patients. The yeast ATP2C1 orthologue PMR1 codes for a Mn(2+)/Ca(2+) transporter that is crucial for cis-Golgi manganese supply. Here, we present evidence that calcium overcomes the lack of Pmr1 through vesicle trafficking-stimulated manganese delivery and requires the endoplasmic reticulum Mn(2+) transporter Spf1 and the late endosome/trans-Golgi Nramp metal transporter Smf2. Smf2 co-localizes with the putative Mn(2+) transporter Atx2, and ATX2 overexpression counteracts the beneficial impact of calcium treatment. Our findings suggest that vesicle trafficking promotes organelle-specific ion interchange and cytoplasmic metal detoxification independent of calcineurin signaling or metal transporter re-localization. Our study identifies an alternative mode for cis-Golgi manganese supply in yeast and provides new perspectives for Hailey-Hailey disease treatment.

  13. Strontium-calcium coadministration stimulates bone matrix osteogenic factor expression and new bone formation in a large animal model.

    PubMed

    Li, Zhaoyang; Lu, William W; Chiu, Peter K Y; Lam, Raymond W M; Xu, Bing; Cheung, Kenneth M C; Leong, John C Y; Luk, Keith D K

    2009-06-01

    Strontium (Sr) has become increasingly attractive for use in the prevention and treatment of osteoporosis by concomitantly inhibiting bone resorption and enhancing bone formation. Strontium shares similar chemical, physical, and biological characteristics with calcium (Ca), which has been widely used as a dietary supplement in osteoporosis. However, the effects of Sr-Ca coadministration on bone growth and remodeling are yet to be extensively reported. In this study, 18 ovariectomized goats were divided into four groups: three groups of five goats each treated with 100 mg/kg/day Ca, Ca plus 24 mg/kg/day Sr (Ca + 24Sr), or Ca plus 40 mg/kg/day Sr (Ca + 40Sr), and three untreated goats fed low calcium feed. Serum Sr levels increased 6- and 10-fold in the Ca + 24Sr and Ca + 40Sr groups, respectively. Similarly, Sr in the bone increased four- and sixfold in these two groups. Sr-Ca coadministration considerably increased bone mineral apposition rate (MAR). The expression of insulin-like growth factor (IGF)-1 and runt-related transcription factor 2 (Runx2) was significantly upregulated within the Ca + 40Sr treatment group; tumor necrosis factor (TNF)-agr; expression was significantly downregulated in the Ca and Ca + 40Sr groups. The results indicate that Sr-Ca coadministration increases osteogenic gene expression and stimulates new bone formation. PMID:19025756

  14. Calcium Stimulates Self-Assembly of Protein Kinase C α In Vitro

    PubMed Central

    Sommese, Ruth F.; Petersen, Karl J.; Ritt, Michael; Karslake, Joshua; Thomas, David D.; Sivaramakrishnan, Sivaraj

    2016-01-01

    Protein kinase C α (PKCα) is a nodal regulator in several intracellular signaling networks. PKCα is composed of modular domains that interact with each other to dynamically regulate spatial-temporal function. We find that PKCα specifically, rapidly and reversibly self-assembles in the presence of calcium in vitro. This phenomenon is dependent on, and can be modulated by an intramolecular interaction between the C1a and C2 protein domains of PKCα. Next, we monitor self-assembly of PKC—mCitrine fusion proteins using time-resolved and steady-state homoFRET. HomoFRET between full-length PKCα molecules is observed when in solution with both calcium and liposomes containing either diacylglycerol (DAG) or phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). Surprisingly, the C2 domain is sufficient to cluster on liposomes containing PI(4,5)P2, indicating the C1a domain is not required for self-assembly in this context. We conclude that three distinct clustered states of PKCα can be formed depending on what combination of cofactors are bound, but Ca2+ is minimally required and sufficient for clustering. PMID:27706148

  15. ELECTROSTATIC CHARGE STIMULATES OXIDATIVE STRESS IN CNS MICROGLIA.

    EPA Science Inventory

    Nanometer size particles carry free radical activity on their surface and can create oxidative stress (OS)-mediated inflammatory changes upon impact. The oxidative burst signals the activation of phage-lineage cells such as peripheral macrophages, Kupffer cells and CNS microgl...

  16. Amorphous Manganese-Calcium Oxides as a Possible Evolutionary Origin for the CaMn4 Cluster in Photosystem II

    NASA Astrophysics Data System (ADS)

    Najafpour, Mohammad Mahdi

    2011-06-01

    In this paper a few calcium-manganese oxides and calcium-manganese minerals are studied as catalysts for water oxidation. The natural mineral marokite is also studied as a catalyst for water oxidation for the first time. Marokite is made up of edge-sharing Mn3+ in a distorted octahedral environment and eight-coordinate Ca2+ centered polyhedral layers. The structure is similar to recent models of the oxygen evolving complex in photosystem II. Thus, the oxygen evolving complex in photosystem II does not have an unusual structure and could be synthesized hydrothermally. Also in this paper, oxygen evolution is studied with marokite (CaMn2O4), pyrolusite (MnO2) and compared with hollandite (Ba0.2Ca0.15K0.3Mn6.9Al0.2Si0.3O16), hausmannite (Mn3O4), Mn2O3.H2O, CaMn3O6.H2O, CaMn4O8.H2O, CaMn2O4.H2O and synthetic marokite (CaMn2O4). I propose that the origin of the oxygen evolving complex in photosystem II resulted from absorption of calcium and manganese ions that were precipitated together in the archean oceans by protocyanobacteria because of changing pH from ~5 to ~8-10. As reported in this paper, amorphous calcium-manganese oxides with different ratios of manganese and calcium are effective catalysts for water oxidation. The bond types and lengths of the calcium and manganese ions in the calcium-manganese oxides are directly comparable to those in the OEC. This primitive structure of these amorphous calcium-manganese compounds could be changed and modified by environmental groups (amino acids) to form the oxygen evolving complex in photosystem II.

  17. Stimulation of polyunsaturated fatty acid oxidation in myocytes by regulating its cellular uptake

    SciTech Connect

    Abdel-aleem, S.; Frangakis, C. ); Badr, M. )

    1991-01-01

    In order to investigate the regulation of polyunsaturated fatty acid oxidation in the heart, the effect of the phosphodiesterase inhibitor enoximone on the oxidation of (1-{sup 14}C) arachidonic acid, and (1-{sup 14}C) arachidonyl-CoA, were studied in adult rat myocytes, and isolated rat heart mitochondria. Enoximone stimulated arachidonate oxidation by 94%, at a concentration of 0.25 mM. The apparent Vmax value of archidonate oxidation in the presence of enoximone was approximately 75% higher than the value observed with the control in isolated myocytes. Also, enoximone stimulated arachidonate uptake by 27% at a concentration of 0.25 mM. On the other hand, enoximone had no effect on the oxidation of (1-{sup 14}C) arachidonyl-CoA in isolated rat heart mitochondria. These results suggest that the oxidation of polyunsaturated fatty acids in myocytes is regulated by the rate of uptake of these acids across sarcolemmal membranes.

  18. Effect of calcium oxide on the efficiency of ferrous ion oxidation and total iron precipitation during ferrous ion oxidation in simulated acid mine drainage treatment with inoculation of Acidithiobacillus ferrooxidans.

    PubMed

    Liu, Fenwu; Zhou, Jun; Jin, Tongjun; Zhang, Shasha; Liu, Lanlan

    2016-01-01

    Calcium oxide was added into ferrous ion oxidation system in the presence of Acidithiobacillus ferrooxidans at concentrations of 0-4.00 g/L. The pH, ferrous ion oxidation efficiency, total iron precipitation efficiency, and phase of the solid minerals harvested from different treatments were investigated during the ferrous ion oxidation process. In control check (CK) system, pH of the solution decreased from 2.81 to 2.25 when ferrous ions achieved complete oxidation after 72 h of Acidithiobacillus ferrooxidans incubation without the addition of calcium oxide, and total iron precipitation efficiency reached 20.2%. Efficiency of ferrous ion oxidation and total iron precipitation was significantly improved when the amount of calcium oxide added was ≤1.33 g/L, and the minerals harvested from systems were mainly a mixture of jarosite and schwertmannite. For example, the ferrous ion oxidation efficiency reached 100% at 60 h and total iron precipitation efficiency was increased to 32.1% at 72 h when 1.33 g/L of calcium oxide was added. However, ferrous ion oxidation and total iron precipitation for jarosite and schwertmannite formation were inhibited if the amount of calcium oxide added was above 2.67 g/L, and large amounts of calcium sulfate dihydrate were generated in systems.

  19. Calcium-Oxidant Signaling Network Regulates AMP-activated Protein Kinase (AMPK) Activation upon Matrix Deprivation*

    PubMed Central

    Sundararaman, Ananthalakshmy; Amirtham, Usha; Rangarajan, Annapoorni

    2016-01-01

    The AMP-activated protein kinase (AMPK) has recently been implicated in anoikis resistance. However, the molecular mechanisms that activate AMPK upon matrix detachment remain unexplored. In this study, we show that AMPK activation is a rapid and sustained phenomenon upon matrix deprivation, whereas re-attachment to the matrix leads to its dephosphorylation and inactivation. Because matrix detachment leads to loss of integrin signaling, we investigated whether integrin signaling negatively regulates AMPK activation. However, modulation of focal adhesion kinase or Src, the major downstream components of integrin signaling, failed to cause a corresponding change in AMPK signaling. Further investigations revealed that the upstream AMPK kinases liver kinase B1 (LKB1) and Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) contribute to AMPK activation upon detachment. In LKB1-deficient cells, we found AMPK activation to be predominantly dependent on CaMKKβ. We observed no change in ATP levels under detached conditions at early time points suggesting that rapid AMPK activation upon detachment was not triggered by energy stress. We demonstrate that matrix deprivation leads to a spike in intracellular calcium as well as oxidant signaling, and both these intracellular messengers contribute to rapid AMPK activation upon detachment. We further show that endoplasmic reticulum calcium release-induced store-operated calcium entry contributes to intracellular calcium increase, leading to reactive oxygen species production, and AMPK activation. We additionally show that the LKB1/CaMKK-AMPK axis and intracellular calcium levels play a critical role in anchorage-independent cancer sphere formation. Thus, the Ca2+/reactive oxygen species-triggered LKB1/CaMKK-AMPK signaling cascade may provide a quick, adaptable switch to promote survival of metastasizing cancer cells. PMID:27226623

  20. Stimulated oxidation of metals (laser, electric field, etc.): Comparative studies

    NASA Astrophysics Data System (ADS)

    Nánai, László; Füle, Miklós

    2014-11-01

    In this report we demonstrate the importance of metal oxides, e.g. thin films and nanostructures, in modern science and technology. The basic laws of oxide thickness on base of diffusion of specimens versus time in different circumstances (Cabrera-Mott and Wagner laws) under the influence of external fields, e.g. electromagnetic field, static electric and magnetic field, are demonstrated. We give experimental results for various metal oxide layers over a wide range of different metals. Theoretical explanations are provided as well for the most reliable circumstances.

  1. Calcium Imaging of Living Astrocytes in the Mouse Spinal Cord following Sensory Stimulation

    PubMed Central

    Cirillo, Giovanni; De Luca, Daniele; Papa, Michele

    2012-01-01

    Astrocytic Ca2+ dynamics have been extensively studied in ex vivo models; however, the recent development of two-photon microscopy and astrocyte-specific labeling has allowed the study of Ca2+ signaling in living central nervous system. Ca2+ waves in astrocytes have been described in cultured cells and slice preparations, but evidence for astrocytic activation during sensory activity is lacking. There are currently few methods to image living spinal cord: breathing and heart-beating artifacts have impeded the widespread application of this technique. We here imaged the living spinal cord by two-photon microscopy in C57BL6/J mice. Through pressurized injection, we specifically loaded spinal astrocytes using the red fluorescent dye sulforhodamine 101 (SR101) and imaged astrocytic Ca2+ levels with Oregon-Green BAPTA-1 (OGB). Then, we studied astrocytic Ca2+ levels at rest and after right electrical hind paw stimulation. Sensory stimulation significantly increased astrocytic Ca2+ levels within the superficial dorsal horn of the spinal cord compared to rest. In conclusion, in vivo morphofunctional imaging of living astrocytes in spinal cord revealed that astrocytes actively participate to sensory stimulation. PMID:23091738

  2. Experimental Calcium Silicate-Based Cement with and without Zirconium Oxide Modulates Fibroblasts Viability.

    PubMed

    Slompo, Camila; Peres-Buzalaf, Camila; Gasque, Kellen Cristina da Silva; Damante, Carla Andreotti; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro; de Oliveira, Rodrigo Cardoso

    2015-01-01

    The aim of this study was to verify whether the use of zirconium oxide as a radiopacifier of an experimental calcium silicate-based cement (WPCZO) leads to cytotoxicity. Fibroblasts were treated with different concentrations (10 mg/mL, 1 mg/mL, and 0.1 mg/mL) of the cements diluted in Dulbecco's modified Eagle's medium (DMEM) for periods of 12, 24, and 48 h. Groups tested were white Portland cement (WPC), white Portland cement with zirconium oxide (WPCZO), and white mineral trioxide aggregate Angelus (MTA). Control group cells were not treated. The cytotoxicity was evaluated through mitochondrial-activity (MTT) and cell-density (crystal violet) assays. All cements showed low cytotoxicity. In general, at the concentration of 10 mg/mL there was an increase in viability of those groups treated with WPC and WPCZO when compared to the control group (p<0.05). A similar profile for the absorbance values was noted among the groups: 10 mg/mL presented an increase in viability compared to the control group. On the other hand, smaller concentrations presented a similar or lower viability compared to the control group, in general. A new dental material composed of calcium silicate-based cement with 20% zirconium oxide as the radiopacifier showed low cytotoxicity as a promising material to be exploited for root-end filling.

  3. Slide fastener reduction of graphene-oxide edges by calcium: insight from ab initio molecular dynamics.

    PubMed

    Xie, Sheng-Yi; Li, Xian-Bin; Tian, Wei Quan; Wang, Dan; Chen, Nian-Ke; Han, Dong; Sun, Hong-Bo

    2014-09-15

    The reduction of graphene oxide can be used as a simple way to produce graphene on a large scale. However, the numerous edges produced by the oxidation of graphite seriously degrade the quality of the graphene and its carrier transport property. In this work, the reduction of oxygen-passivated graphene edges and the subsequent linking of separated graphene sheets by calcium are investigated by using first-principles calculations. The calculations show that calcium can effectively remove the oxygen groups from two adjacent edges. The joining point of the edges serves as the starting point of the reduction and facilitates the reaction. Once the oxygen groups are removed, the crack is sutured. If the joining point is lacking, it becomes difficult to zip the separated fragments. A general electron-reduction model and a random atom-reduction model are suggested for these two situations. The present study sheds light on the reduction of graphene-oxide edges by using reactive metals to give large-sized graphene through a simple chemical reaction.

  4. Cardiac responses to β-adrenoceptor stimulation is partly dependent on mitochondrial calcium uniporter activity

    PubMed Central

    Fernández-Sada, E; Silva-Platas, C; Villegas, C A; Rivero, S L; Willis, B C; García, N; Garza, J R; Oropeza-Almazán, Y; Valverde, C A; Mazzocchi, G; Zazueta, C; Torre-Amione, G; García-Rivas, G

    2014-01-01

    Background and Purpose Despite the importance of mitochondrial Ca2+ to metabolic regulation and cell physiology, little is known about the mechanisms that regulate Ca2+ entry into the mitochondria. Accordingly, we established a system to determine the role of the mitochondrial Ca2+ uniporter in an isolated heart model, at baseline and during increased workload following β-adrenoceptor stimulation. Experimental Approach Cardiac contractility, oxygen consumption and intracellular Ca2+ transients were measured in ex vivo perfused murine hearts. Ru360 and spermine were used to modify mitochondrial Ca2+ uniporter activity. Changes in mitochondrial Ca2+ content and energetic phosphate metabolite levels were determined. Key Results The addition of Ru360, a selective inhibitor of the mitochondrial Ca2+ uniporter, induced progressively and sustained negative inotropic effects that were dose-dependent with an EC50 of 7 μM. Treatment with spermine, a uniporter agonist, showed a positive inotropic effect that was blocked by Ru360. Inotropic stimulation with isoprenaline elevated oxygen consumption (2.7-fold), Ca2+-dependent activation of pyruvate dehydrogenase (5-fold) and mitochondrial Ca2+ content (2.5-fold). However, in Ru360-treated hearts, this parameter was attenuated. In addition, β-adrenoceptor stimulation in the presence of Ru360 did not affect intracellular Ca2+ handling, PKA or Ca2+/calmodulin-dependent PK signalling. Conclusions and Implications Inhibition of the mitochondrial Ca2+ uniporter decreases β-adrenoceptor response, uncoupling between workload and production of energetic metabolites. Our results support the hypothesis that the coupling of workload and energy supply is partly dependent on mitochondrial Ca2+ uniporter activity. PMID:24628066

  5. Calcium released by photolysis of DM-nitrophen stimulates transmitter release at squid giant synapse.

    PubMed Central

    Delaney, K R; Zucker, R S

    1990-01-01

    1. Transmitter release at the squid giant synapse was stimulated by photolytic release of Ca2+ from the 'caged' Ca2+ compound DM-nitrophen (Kaplan & Ellis-Davies, 1988) inserted into presynaptic terminals. 2. Competing binding reactions cause the amount of Ca2+ released by DM-nitrophen photolysis to depend on the concentrations of DM-nitrophen, total Ca2+, Mg+, ATP and native cytoplasmic Ca2+ buffer. Measurements of presynaptic [Ca2+] changes by co-injection of the fluorescent indicator dye Fura-2 show that DM-nitrophen photolysis causes a transient rise in Ca2+ followed by decay within about 150 ms to an increased steady-state level. 3. Rapid photolysis of Ca2(+)-loaded nitrophen within the presynaptic terminal was followed in less than a millisecond by depolarization of the postsynaptic membrane. As with action potential-evoked excitatory postsynaptic potentials (EPSPs), the light-evoked response was partially and reversibly blocked by 1-3 mM-kainic acid which desensitizes postsynaptic glutamate receptors. 4. Release was similar in magnitude and rate to normal action potential-mediated EPSPs. 5. The release of transmitter by photolysis of Ca2(+)-loaded DM-nitrophen was not affected by removal of Ca2+ from the saline or addition of tetrodotoxin. Photolysis of DM-nitrophen injected into presynaptic terminals without added Ca2+ did not stimulate release of transmitter nor did it interfere with normal action potential-mediated release. 6. Stimulation of presynaptic action potentials in Ca2(+)-free saline during the light-evoked response did not elicit increased release of transmitter if the ganglion was bathed in Ca2(+)-free saline, i.e. in the absence of Ca2+ influx. Increasing the intensity of the light or stimulating presynaptic action potentials in Ca2(+)-containing saline increased the release of transmitter. Therefore the failure of presynaptic voltage change to increase transmitter release resulting from release of caged Ca2+ was not due to saturation or

  6. Insulin-like growth factor I stimulates lipid oxidation, reduces protein oxidation, and enhances insulin sensitivity in humans.

    PubMed Central

    Hussain, M A; Schmitz, O; Mengel, A; Keller, A; Christiansen, J S; Zapf, J; Froesch, E R

    1993-01-01

    To elucidate the effects of insulin-like growth factor I (IGF-I) on fuel oxidation and insulin sensitivity, eight healthy subjects were treated with saline and recombinant human (IGF-I (10 micrograms/kg.h) during 5 d in a crossover, randomized fashion, while receiving an isocaloric diet (30 kcal/kg.d) throughout the study period. On the third and fourth treatment days, respectively, an L-arginine stimulation test and an intravenous glucose tolerance test were performed. A euglycemic, hyperinsulinemic clamp combined with indirect calorimetry and a glucose tracer infusion were performed on the fifth treatment day. IGF-I treatment led to reduced fasting and stimulated (glucose and/or L-arginine) insulin and growth hormone secretion. Basal and stimulated glucagon secretion remained unchanged. Intravenous glucose tolerance was unaltered despite reduced insulin secretion. Resting energy expenditure and lipid oxidation were both elevated, while protein oxidation was reduced, and glucose turnover rates were unaltered on the fifth treatment day with IGF-I as compared to the control period. Enhanced lipolysis was reflected by elevated circulating free fatty acids. Moreover, insulin-stimulated oxidative and nonoxidative glucose disposal (i.e., insulin sensitivity) were enhanced during IGF-I treatment. Thus, IGF-I treatment leads to marked changes in lipid and protein oxidation, whereas, at the dose used, carbohydrate metabolism remains unaltered in the face of reduced insulin levels and enhanced insulin sensitivity. Images PMID:8227340

  7. QSAR analysis for nano-sized layered manganese-calcium oxide in water oxidation: An application of chemometric methods in artificial photosynthesis.

    PubMed

    Shahbazy, Mohammad; Kompany-Zareh, Mohsen; Najafpour, Mohammad Mahdi

    2015-11-01

    Water oxidation is among the most important reactions in artificial photosynthesis, and nano-sized layered manganese-calcium oxides are efficient catalysts toward this reaction. Herein, a quantitative structure-activity relationship (QSAR) model was constructed to predict the catalytic activities of twenty manganese-calcium oxides toward water oxidation using multiple linear regression (MLR) and genetic algorithm (GA) for multivariate calibration and feature selection, respectively. Although there are eight controlled parameters during synthesizing of the desired catalysts including ripening time, temperature, manganese content, calcium content, potassium content, the ratio of calcium:manganese, the average manganese oxidation state and the surface of catalyst, by using GA only three of them (potassium content, the ratio of calcium:manganese and the average manganese oxidation state) were selected as the most effective parameters on catalytic activities of these compounds. The model's accuracy criteria such as R(2)test and Q(2)test in order to predict catalytic rate for external test set experiments; were equal to 0.941 and 0.906, respectively. Therefore, model reveals acceptable capability to anticipate the catalytic activity.

  8. QSAR analysis for nano-sized layered manganese-calcium oxide in water oxidation: An application of chemometric methods in artificial photosynthesis.

    PubMed

    Shahbazy, Mohammad; Kompany-Zareh, Mohsen; Najafpour, Mohammad Mahdi

    2015-11-01

    Water oxidation is among the most important reactions in artificial photosynthesis, and nano-sized layered manganese-calcium oxides are efficient catalysts toward this reaction. Herein, a quantitative structure-activity relationship (QSAR) model was constructed to predict the catalytic activities of twenty manganese-calcium oxides toward water oxidation using multiple linear regression (MLR) and genetic algorithm (GA) for multivariate calibration and feature selection, respectively. Although there are eight controlled parameters during synthesizing of the desired catalysts including ripening time, temperature, manganese content, calcium content, potassium content, the ratio of calcium:manganese, the average manganese oxidation state and the surface of catalyst, by using GA only three of them (potassium content, the ratio of calcium:manganese and the average manganese oxidation state) were selected as the most effective parameters on catalytic activities of these compounds. The model's accuracy criteria such as R(2)test and Q(2)test in order to predict catalytic rate for external test set experiments; were equal to 0.941 and 0.906, respectively. Therefore, model reveals acceptable capability to anticipate the catalytic activity. PMID:25591399

  9. Intracellular calcium mobilization and phospholipid degradation in sphingosylphosphorylcholine-stimulated human airway epithelial cells.

    PubMed Central

    Orlati, S; Porcelli, A M; Hrelia, S; Lorenzini, A; Rugolo, M

    1998-01-01

    Extracellular sphingosylphosphorylcholine (SPC) caused a remarkable elevation in the intracellular Ca2+ concentration ([Ca2+]i) in immortalized human airway epithelial cells (CFNP9o-). An increase in total inositol phosphates formation was determined; however, the dose responses for [Ca2+]i elevation and inositol phosphates production were slightly different and, furthermore, PMA and pertussis toxin almost completely inhibited [Ca2+]i mobilization by SPC, whereas inositol phosphates production was only partially reduced. The possible direct interaction of SPC with Ca2+ channels of intracellular stores was determined by experiments with permeabilized cells, where SPC failed to evoke Ca2+ release, whereas lysophosphatidic acid was shown to be effective. The level of phosphatidic acid was increased by SPC only in the presence of AACOCF3, a specific inhibitor of phospholipase A2 (PLA2) and blocked by both pertussis toxin and R59022, an inhibitor of diacylglycerol kinase. R59022 enhanced diacylglycerol production by SPC and also significantly reduced [Ca2+]i mobilization. Only polyunsaturated diacylglycerol and phosphatidic acid were generated by SPC. Lastly, SPC caused stimulation of arachidonic acid release, indicating the involvement of PLA2. Taken together, these data suggest that, after SPC stimulation, phospholipase C-derived diacylglycerol is phosphorylated by a diacylglycerol kinase to phosphatidic acid, which is further hydrolysed by PLA2 activity to arachidonic and lysophosphatidic acids. We propose that lysophosphatidic acid might be the intracellular messenger able to release Ca2+ from internal stores. PMID:9729473

  10. Nitric oxide directly activates calcium-dependent potassium channels in vascular smooth muscle.

    PubMed

    Bolotina, V M; Najibi, S; Palacino, J J; Pagano, P J; Cohen, R A

    1994-04-28

    Nitric oxide is the major endothelium-derived relaxing factor (EDRF), and it is thought to relax smooth muscle cells by stimulation of guanylate cyclase, accumulation of its product cyclic GMP, and cGMP-dependent modification of several intracellular processes, including activation of potassium channels through cGMP-dependent protein kinase. Here we present evidence that both exogenous nitric oxide and native EDRF can directly activate single Ca(2+)-dependent K+ channels (K+Ca) in cell-free membrane patches without requiring cGMP. Under conditions when guanylate cyclase was inhibited by methylene blue, considerable relaxation of rabbit aorta to nitric oxide persisted which was blocked by charybdotoxin, a specific inhibitor of K+Ca channels. These studies demonstrate a novel direct action of nitric oxide on K+Ca channels. PMID:7512692

  11. Ca2+ stimulates COX-2 expression through calcium-sensing receptor in fibroblasts.

    PubMed

    Ogata, Sachie; Kubota, Yasutaka; Satoh, Shinji; Ito, Shinich; Takeuchi, Hiroshi; Ashizuka, Megumi; Shirasuna, Kanemitsu

    2006-12-29

    Fibroblasts isolated from jaw cysts expressed calcium-sensing receptor (CasR). In the fibroblasts elevated extracellular Ca(2+) ([Ca(2+)](o)) increased fluo-3 fluorescence intensity, and the production of inositol(1,4,5)trisphosphate and active protein kinase C. Phospholipase C inhibitor U-73122 attenuated the Ca(2+)-induced increase in fluo-3 fluorescence intensity. Elevated [Ca(2+)](o) enhanced the expression of cyclooxygenase-2 (COX-2) mRNA and protein, and the secretion of prostaglandin E(2) in the fibroblasts. CasR activator neomycin also increased the expression of COX-2 mRNA, and U-73122 attenuated the Ca(2+)-induced expression of COX-2 mRNA. Elevated [Ca(2+)](o)-induced phosphorylation of extracellular signal-regulated protein kinase-1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK), and U-73122 inhibited the Ca(2+)-induced phosphorylation. The inhibitors for each kinase, PD98059, SB203580, and SP600125, attenuated the Ca(2+)-induced expression of COX-2 mRNA. These results suggest that in jaw cyst fibroblasts elevated extracellular Ca(2+) may enhance COX-2 expression via the activation of ERK1/2, p38 MAPK, and JNK through CasR.

  12. Absorption of calcium ions on oxidized graphene sheets and study its dynamic behavior by kinetic and isothermal models

    NASA Astrophysics Data System (ADS)

    Fathy, Mahmoud; Abdel Moghny, Th.; Mousa, Mahmoud Ahmed; El-Bellihi, Abdel-Hameed A.-A.; Awadallah, Ahmed E.

    2016-07-01

    Sorption of calcium ion from the hard underground water using novel oxidized graphene (GO) sheets was studied in this paper. Physicochemical properties and microstructure of graphene sheets were investigated using Raman spectrometer, thermogravimetry analyzer, transmission electron microscope, scanning electron microscope. The kinetics adsorption of calcium on graphene oxide sheets was examined using Lagergren first and second orders. The results show that the Lagergren second-order was the best-fit model that suggests the conception process of calcium ion adsorption on the Go sheets. For isothermal studies, the Langmuir and Freundlich isotherm models were used at temperatures ranging between 283 and 313 K. Thermodynamic parameters resolved at 283, 298 and 313 K indicating that the GO adsorption was exothermic spontaneous process. Finally, the graphene sheets show high partiality toward calcium particles and it will be useful in softening and treatment of hard water.

  13. Coal-gasification and tar-conversion reactions over calcium oxide. Annual progress report, August 1, 1981-October 31, 1982

    SciTech Connect

    Longwell, J.P.; Chang, C.S.; Peters, W.A.

    1983-01-01

    This research focusses on low temperature (723-1123 K) effects of calcium oxide on coal gasification and coal pyrolysis. The general objective of the present research is to investigate the chemistry and global kinetics of thermal reactions of freshly-formed tars in the presence of calcium oxide, and thereby assess the potential application for achieving improved overall gas yields and product quality in practical processes. Construction and debugging of the experimental system, designed to achieve this goal, have been completed. Preliminary runs showed that the system can be operated satisfactorily according to the design specifications. The extent of fresh tar cracking can be controlled by independently adjusting the major operating variables, such as reactor temperature, contact time (with active calcium oxide), and system pressure. The collection systems and the analytical techniques employed for characterizing the pyrolysis products have been identified. A standard procedure for reproducibly generating packed beds of active calcium oxide that exhibited minimal variation in stone surface area along their axis is under development. A 2-step calcination protocol shows promise for achieving this goal for well-defined experiments. Preliminary results of coal volatile generation and cracking experiments indicate that calcium oxide can drastically reduce the absolute yield of tars and significantly increase the production and yields of methane and ethylene gases. Overall material balances also appear to be satisfactory.

  14. Reactive oxygen species and nitric oxide mediate plasticity of neuronal calcium signaling

    NASA Astrophysics Data System (ADS)

    Yermolaieva, Olena; Brot, Nathan; Weissbach, Herbert; Heinemann, Stefan H.; Hoshi, Toshinori

    2000-01-01

    Reactive oxygen species (ROS) and nitric oxide (NO) are important participants in signal transduction that could provide the cellular basis for activity-dependent regulation of neuronal excitability. In young rat cortical brain slices and undifferentiated PC12 cells, paired application of depolarization/agonist stimulation and oxidation induces long-lasting potentiation of subsequent Ca2+ signaling that is reversed by hypoxia. This potentiation critically depends on NO production and involves cellular ROS utilization. The ability to develop the Ca2+ signal potentiation is regulated by the developmental stage of nerve tissue, decreasing markedly in adult rat cortical neurons and differentiated PC12 cells.

  15. Electrical stimulation modulates Wnt signaling and regulates genes for the motor endplate and calcium binding in muscle of rats with spinal cord transection

    PubMed Central

    2013-01-01

    Background Spinal cord injury (SCI) results in muscle atrophy and a shift of slow oxidative to fast glycolytic fibers. Electrical stimulation (ES) at least partially restores muscle mass and fiber type distribution. The objective of this study was to was to characterize the early molecular adaptations that occur in rat soleus muscle after initiating isometric resistance exercise by ES for one hour per day for 1, 3 or 7 days when ES was begun 16 weeks after SCI. Additionally, changes in mRNA levels after ES were compared with those induced in soleus at the same time points after gastrocnemius tenotomy (GA). Results ES increased expression of Hey1 and Pitx2 suggesting increased Notch and Wnt signaling, respectively, but did not normalize RCAN1.4, a measure of calcineurin/NFAT signaling, or PGC-1ß mRNA levels. ES increased PGC-1α expression but not that of slow myofibrillar genes. Microarray analysis showed that after ES, genes coding for calcium binding proteins and nicotinic acetylcholine receptors were increased, and the expression of genes involved in blood vessel formation and morphogenesis was altered. Of the 165 genes altered by ES only 16 were also differentially expressed after GA, of which 12 were altered in the same direction by ES and GA. In contrast to ES, GA induced expression of genes related to oxidative phosphorylation. Conclusions Notch and Wnt signaling may be involved in ES-induced increases in the mass of paralyzed muscle. Molecular adaptations of paralyzed soleus to resistance exercise are delayed or defective compared to normally innervated muscle. PMID:23914941

  16. Calcium imaging reveals glial involvement in transcranial direct current stimulation-induced plasticity in mouse brain

    PubMed Central

    Monai, Hiromu; Ohkura, Masamichi; Tanaka, Mika; Oe, Yuki; Konno, Ayumu; Hirai, Hirokazu; Mikoshiba, Katsuhiko; Itohara, Shigeyoshi; Nakai, Junichi; Iwai, Youichi; Hirase, Hajime

    2016-01-01

    Transcranical direct current stimulation (tDCS) is a treatment known to ameliorate various neurological conditions and enhance memory and cognition in humans. tDCS has gained traction for its potential therapeutic value; however, little is known about its mechanism of action. Using a transgenic mouse expressing G-CaMP7 in astrocytes and a subpopulation of excitatory neurons, we find that tDCS induces large-amplitude astrocytic Ca2+ surges across the entire cortex with no obvious changes in the local field potential. Moreover, sensory evoked cortical responses are enhanced after tDCS. These enhancements are dependent on the alpha-1 adrenergic receptor and are not observed in IP3R2 (inositol trisphosphate receptor type 2) knockout mice, in which astrocytic Ca2+ surges are absent. Together, we propose that tDCS changes the metaplasticity of the cortex through astrocytic Ca2+/IP3 signalling. PMID:27000523

  17. Computational modeling of neurons: intensity-duration relationship of extracellular electrical stimulation for changes in intracellular calcium.

    PubMed

    Adams, Robert D; Willits, Rebecca K; Harkins, Amy B

    2016-01-01

    In many instances of extensive nerve damage, the injured nerve never adequately heals, leaving lack of nerve function. Electrical stimulation (ES) has been shown to increase the rate and orient the direction of neurite growth, and is a promising therapy. However, the mechanism in which ES affects neuronal growth is not understood, making it difficult to compare existing ES protocols or to design and optimize new protocols. We hypothesize that ES acts by elevating intracellular calcium concentration ([Ca(2+)]i) via opening voltage-dependent Ca(2+) channels (VDCCs). In this work, we have created a computer model to estimate the ES Ca(2+) relationship. Using COMSOL Multiphysics, we modeled a small dorsal root ganglion (DRG) neuron that includes one Na(+) channel, two K(+) channels, and three VDCCs to estimate [Ca(2+)]i in the soma and growth cone. As expected, the results show that an ES that generates action potentials (APs) can efficiently raise the [Ca(2+)]i of neurons. More interestingly, our simulation results show that sub-AP ES can efficiently raise neuronal [Ca(2+)]i and that specific high-voltage ES can preferentially raise [Ca(2+)]i in the growth cone. The intensities and durations of ES on modeled growth cone calcium rise are consistent with directionality and orientation of growth cones experimentally shown by others. Finally, this model provides a basis to design experimental ES pulse parameters, including duration, intensity, pulse-train frequency, and pulse-train duration to efficiently raise [Ca(2+)]i in neuronal somas or growth cones. PMID:26510759

  18. Combinatorial incorporation of fluoride and cobalt ions into calcium phosphates to stimulate osteogenesis and angiogenesis.

    PubMed

    Birgani, Zeinab Tahmasebi; Gharraee, Nazli; Malhotra, Angad; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-02-29

    Bone healing requires two critical mechanisms, angiogenesis and osteogenesis. In order to improve bone graft substitutes, both mechanisms should be addressed simultaneously. While the individual effects of various bioinorganics have been studied, an understanding of the combinatorial effects is lacking. Cobalt and fluoride ions, in appropriate concentrations, are known to individually favor the vascularization and mineralization processes, respectively. This study investigated the potential of using a combination of fluoride and cobalt ions to simultaneously promote osteogenesis and angiogenesis in human mesenchymal stromal cells (hMSCs). Using a two-step biomimetic method, wells of tissue culture plates were coated with a calcium phosphate (CaP) layer without or with the incorporation of cobalt, fluoride, or both. In parallel, hMSCs were cultured on uncoated well plates, and cultured with cobalt and/or fluoride ions within the media. The results revealed that cobalt ions increased the expression of angiogenic markers, with the effects being stronger when the ions were added as a dissolved salt in cell medium as compared to incorporation into CaP. Cobalt ions generally suppressed the ALP activity, the expression of osteogenic genes, and the level of mineralization, regardless of delivery method. Fluoride ions, individually or in combination with cobalt, significantly increased the expression of many of the selected osteogenic markers, as well as mineral deposition. This study demonstrates an approach to simultaneously target the two essential mechanisms in bone healing: angiogenesis and osteogenesis. The incorporation of cobalt and fluoride into CaPs is a promising method to improve the biological performance of fully synthetic bone graft substitutes.

  19. Combinatorial incorporation of fluoride and cobalt ions into calcium phosphates to stimulate osteogenesis and angiogenesis.

    PubMed

    Birgani, Zeinab Tahmasebi; Gharraee, Nazli; Malhotra, Angad; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-02-01

    Bone healing requires two critical mechanisms, angiogenesis and osteogenesis. In order to improve bone graft substitutes, both mechanisms should be addressed simultaneously. While the individual effects of various bioinorganics have been studied, an understanding of the combinatorial effects is lacking. Cobalt and fluoride ions, in appropriate concentrations, are known to individually favor the vascularization and mineralization processes, respectively. This study investigated the potential of using a combination of fluoride and cobalt ions to simultaneously promote osteogenesis and angiogenesis in human mesenchymal stromal cells (hMSCs). Using a two-step biomimetic method, wells of tissue culture plates were coated with a calcium phosphate (CaP) layer without or with the incorporation of cobalt, fluoride, or both. In parallel, hMSCs were cultured on uncoated well plates, and cultured with cobalt and/or fluoride ions within the media. The results revealed that cobalt ions increased the expression of angiogenic markers, with the effects being stronger when the ions were added as a dissolved salt in cell medium as compared to incorporation into CaP. Cobalt ions generally suppressed the ALP activity, the expression of osteogenic genes, and the level of mineralization, regardless of delivery method. Fluoride ions, individually or in combination with cobalt, significantly increased the expression of many of the selected osteogenic markers, as well as mineral deposition. This study demonstrates an approach to simultaneously target the two essential mechanisms in bone healing: angiogenesis and osteogenesis. The incorporation of cobalt and fluoride into CaPs is a promising method to improve the biological performance of fully synthetic bone graft substitutes. PMID:26929187

  20. Characterization of a calcium phospho-silicated apatite with iron oxide inclusions

    NASA Astrophysics Data System (ADS)

    Desport, Barthélémy; Carpena, Joëlle; Lacout, Jean-Louis; Borschneck, Daniel; Gattacceca, Jérôme

    2011-02-01

    An iron oxide containing calcium phosphate-silicate hydroxyapatite was synthesized by calcination at 900 °C of a sample obtained by precipitation in basic aqueous solution of Ca, P, Si, Fe and Mg containing acidic solution made from dissolution of natural minerals. XRD and FTIR were used for crystallographic characterization of the main apatitic phase. Its composition was determined using ICP-AES. EDX coupled with SEM and TEM evidenced the heterogeneity of this compound and the existence of iron-magnesium oxide. Magnetic analyses highlighted that this phase was non-stoichiometric magnesioferrite (Mg 1.2Fe 1.8O 3.9) spherical nanoparticles. Those analyses also put into evidence the role of calcination in synthesis. Carbonates detected by FTIR and estimated by SEM-EDX in non-calcinated sample were removed from apatitic structure, and crystallization of apatite was enhanced during heating. Moreover, there was phase segregation that led to magnesioferrite formation.

  1. Reactions of calcium orthosilicate and barium zirconate with oxides and sulfates of various elements

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1979-01-01

    Calcium orthosilicate and barium zirconate were evaluated as the insulation layer of thermal barrier coatings for air cooled gas turbine components. Their reactions with various oxides and sulfates were studied at 1100 C and 1300 C for times ranging up to 400 and 200 hours, respectively. These oxides and sulfates represent potential impurities or additives in gas turbine fuels and in turbine combustion air, as well as elements of potential bond coat alloys. The phase compositions of the reaction products were determined by X-ray diffraction analysis. BaZrO3 and 2CaO-SiO2 both reacted with P2O5, V2O5, Cr2O3, Al2O3, and SiO2. In addition, 2CaO-SiO2 reacted with Na2O, BaO, MgO, and CoO and BaZrO3 reacted with Fe2O3.

  2. Calcium-sensing receptor activation contributed to apoptosis stimulates TRPC6 channel in rat neonatal ventricular myocytes

    SciTech Connect

    Sun, Yi-hua; Li, Yong-quan; Feng, Shan-li; Li, Bao-xin; Pan, Zhen-wei; Xu, Chang-qing; Li, Ting-ting; Yang, Bao-feng

    2010-04-16

    Capacitative calcium entry (CCE) refers to the influx of calcium through plasma membrane channels activated on depletion of endoplasmic sarcoplasmic/reticulum (ER/SR) Ca{sup 2+} stores, which is performed mainly by the transient receptor potential (TRP) channels. TRP channels are expressed in cardiomyocytes. Calcium-sensing receptor (CaR) is also expressed in rat cardiac tissue and plays an important role in mediating cardiomyocyte apoptosis. However, there are no data regarding the link between CaR and TRP channels in rat heart. In this study, in rat neonatal myocytes, by Ca{sup 2+} imaging, we found that the depletion of ER/SR Ca{sup 2+} stores by thapsigargin (TG) elicited a transient rise in cytoplasmic Ca{sup 2+} ([Ca{sup 2+}]{sub i}), followed by sustained increase depending on extracellular Ca{sup 2+}. But, TRP channels inhibitor (SKF96365), not L-type channels or the Na{sup +}/Ca{sup 2+} exchanger inhibitors, inhibited [Ca{sup 2+}]{sub i} relatively high. Then, we found that the stimulation of CaR with its activator gadolinium chloride (GdCl{sub 3}) or by an increased extracellular Ca{sup 2+}([Ca{sup 2+}]{sub o}) increased the concentration of intracelluar Ca{sup 2+}, whereas, the sustained elevation of [Ca{sup 2+}]{sub i} was reduced in the presence of SKF96365. Similarly, the duration of [Ca{sup 2+}]{sub i} increase was also shortened in the absence of extracellular Ca{sup 2+}. Western blot analysis showed that GdCl{sub 3} increased the expression of TRPC6, which was reversed by SKF96365. Additionally, SKF96365 reduced cardiomyocyte apoptosis induced by GdCl{sub 3}. Our results suggested that CCE exhibited in rat neonatal myocytes and CaR activation induced Ca{sup 2+}-permeable cationic channels TRPCs to gate the CCE, for which TRPC6 was one of the most likely candidates. TRPC6 channel was functionally coupled with CaR to enhance the cardiomyocyte apoptosis.

  3. High Sodium-Induced Oxidative Stress and Poor Anticrystallization Defense Aggravate Calcium Oxalate Crystal Formation in Rat Hyperoxaluric Kidneys

    PubMed Central

    Huang, Ho-Shiang; Ma, Ming-Chieh

    2015-01-01

    Enhanced sodium excretion is associated with intrarenal oxidative stress. The present study evaluated whether oxidative stress caused by high sodium (HS) may be involved in calcium oxalate crystal formation. Male rats were fed a sodium-depleted diet. Normal-sodium and HS diets were achieved by providing drinking water containing 0.3% and 3% NaCl, respectively. Rats were fed a sodium-depleted diet with 5% hydroxyl-L-proline (HP) for 7 and 42 days to induce hyperoxaluria and/or calcium oxalate deposition. Compared to normal sodium, HS slightly increased calcium excretion despite diuresis; however, the result did not reach statistical significance. HS did not affect the hyperoxaluria, hypocalciuria or supersaturation caused by HP; however, it increased calcium oxalate crystal deposition soon after 7 days of co-treatment. Massive calcium oxalate formation and calcium crystal excretion in HS+HP rats were seen after 42 days of treatment. HP-mediated hypocitraturia was further exacerbated by HS. Moreover, HS aggravated HP-induced renal injury and tubular damage via increased apoptosis and oxidative stress. Increased urinary malondialdehyde excretion, in situ superoxide production, NAD(P)H oxidase and xanthine oxidase expression and activity, and decreased antioxidant enzyme expression or activity in the HS+HP kidney indicated exaggerated oxidative stress. Interestingly, this redox imbalance was associated with reduced renal osteopontin and Tamm-Horsfall protein expression (via increased excretion) and sodium-dependent dicarboxylate cotransporter NaDC-1 upregulation. Collectively, our results demonstrate that a HS diet induces massive crystal formation in the hyperoxaluric kidney; this is not due to increased urinary calcium excretion but is related to oxidative injury and loss of anticrystallization defense. PMID:26241473

  4. High Sodium-Induced Oxidative Stress and Poor Anticrystallization Defense Aggravate Calcium Oxalate Crystal Formation in Rat Hyperoxaluric Kidneys.

    PubMed

    Huang, Ho-Shiang; Ma, Ming-Chieh

    2015-01-01

    Enhanced sodium excretion is associated with intrarenal oxidative stress. The present study evaluated whether oxidative stress caused by high sodium (HS) may be involved in calcium oxalate crystal formation. Male rats were fed a sodium-depleted diet. Normal-sodium and HS diets were achieved by providing drinking water containing 0.3% and 3% NaCl, respectively. Rats were fed a sodium-depleted diet with 5% hydroxyl-L-proline (HP) for 7 and 42 days to induce hyperoxaluria and/or calcium oxalate deposition. Compared to normal sodium, HS slightly increased calcium excretion despite diuresis; however, the result did not reach statistical significance. HS did not affect the hyperoxaluria, hypocalciuria or supersaturation caused by HP; however, it increased calcium oxalate crystal deposition soon after 7 days of co-treatment. Massive calcium oxalate formation and calcium crystal excretion in HS+HP rats were seen after 42 days of treatment. HP-mediated hypocitraturia was further exacerbated by HS. Moreover, HS aggravated HP-induced renal injury and tubular damage via increased apoptosis and oxidative stress. Increased urinary malondialdehyde excretion, in situ superoxide production, NAD(P)H oxidase and xanthine oxidase expression and activity, and decreased antioxidant enzyme expression or activity in the HS+HP kidney indicated exaggerated oxidative stress. Interestingly, this redox imbalance was associated with reduced renal osteopontin and Tamm-Horsfall protein expression (via increased excretion) and sodium-dependent dicarboxylate cotransporter NaDC-1 upregulation. Collectively, our results demonstrate that a HS diet induces massive crystal formation in the hyperoxaluric kidney; this is not due to increased urinary calcium excretion but is related to oxidative injury and loss of anticrystallization defense.

  5. Microparticulated and nanoparticulated zirconium oxide added to calcium silicate cement: Evaluation of physicochemical and biological properties.

    PubMed

    Silva, Guilherme F; Bosso, Roberta; Ferino, Rafael V; Tanomaru-Filho, Mário; Bernardi, Maria I B; Guerreiro-Tanomaru, Juliane M; Cerri, Paulo S

    2014-12-01

    The physicochemical and biological properties of calcium silicate-based cement (CS) associated to microparticulated (micro) or nanoparticulated (nano) zirconium oxide (ZrO2 ) were compared with CS and bismuth oxide (BO) with CS. The pH, release of calcium ions, radiopacity, setting time, and compression strength of the materials were evaluated. The tissue reaction promoted by these materials in the subcutaneous was also investigated by morphological, immunohistochemical, and quantitative analyses. For this purpose, polyethylene tubes filled with materials were implanted into rat subcutaneous. After 7, 15, 30, and 60 days, the tubes surrounded by capsules were fixed and embedded in paraffin. In the H&E-stained sections, the number of inflammatory cells (ICs) in the capsule was obtained. Moreover, detection of interleukin-6 (IL-6) by immunohistochemistry and number of IL-6 immunolabeled cells were carried out. von Kossa method was also performed. The differences among the groups were subjected to Tukey test (p ≤ 0.05). The solutions containing the materials presented an alkaline pH and released calcium ions. The addition of radiopacifiers increased setting time and radiopacity of CS. A higher compressive strength in the CS + ZrO2 (micro and nano) was found compared with CS + BO. The number of IC and IL-6 positive cells in the materials with ZrO2 was significantly reduced in comparison with CS + BO. von Kossa-positive structures were observed adjacent to implanted materials. The ZrO2 associated to the CS provides satisfactory physicochemical properties and better biological response than BO. Thus, ZrO2 may be a good alternative for use as radiopacifying agent in substitution to BO.

  6. Immune stimulation following dermal exposure to unsintered indium tin oxide.

    PubMed

    Brock, Kristie; Anderson, Stacey E; Lukomska, Ewa; Long, Carrie; Anderson, Katie; Marshall, Nikki; Meade, B Jean

    2014-01-01

    In recent years, several types of pulmonary pathology, including alveolar proteinosis, fibrosis, and emphysema, have been reported in workers in the indium industry. To date, there remains no clear understanding of the underlying mechanism(s). Pulmonary toxicity studies in rats and mice have demonstrated the development of mediastinal lymph node hyperplasia and granulomas of mediastinal lymph nodes and bronchus-associated lymphoid tissues following exposure to indium tin oxide. Given the association between exposure to other metals and the development of immune-mediated diseases, these studies were undertaken to begin to investigate the immuno-modulatory potential of unsintered indium tin oxide (uITO) in a mouse model. Using modifications of the local lymph node assay, BALB/c mice (five animals/group) were exposed topically via intact or breached skin or injected intradermally at the base of the ear pinnae with either vehicle or increasing concentrations 2.5-10% uITO (90:10 indium oxide/tin oxide, particle size <50 nm). Dose-responsive increases in lymphocyte proliferation were observed with a calculated EC3 of 4.7% for the intact skin study. Phenotypic analysis of draining lymph node cells following intradermal injection with 5% uITO yielded a profile consistent with a T-cell-mediated response. These studies demonstrate the potential for uITO to induce sensitization and using lymphocyte proliferation as a biomarker of exposure, and demonstrate the potential for uITO to penetrate both intact and breached skin.

  7. Oxidative damage increases intracellular free calcium [Ca2+]i concentration in human erythrocytes incubated with lead.

    PubMed

    Quintanar-Escorza, M A; González-Martínez, M T; del Pilar, Intriago-Ortega Ma; Calderón-Salinas, J V

    2010-08-01

    One important effect of lead toxicity in erythrocytes consists of increasing [Ca(2+)](i) which in turn may cause alterations in cell shape and volume and it is associated with cellular rigidity, hemolysis, senescence and apoptosis. In this work, we proposed the use of erythrocytes incubated with Pb(2+) to assess association of the mechanisms of lead erythrocyte oxidative damage and calcium homeostasis. Lead incubation produced an increase in [Ca(2+)](i) dose- and time-dependent, which mainly involved Ca(2+) entry mechanism. Additionally, in this in vitro model alterations similar to erythrocytes of lead-exposed workers were produced: Increase in Ca(2+) influx, decrease in (Ca(2+)-Mg(2+))-ATPase activity and GSH/GSGG ratio; increase in lipoperoxidation, protein carbonylation and osmotic fragility accompanied of dramatic morphological changes. Co-incubation with trolox, a soluble vitamin-E analog is able to prevent these alterations indicating that lead damage mechanism is strongly associated with oxidative damage with an intermediate toxic effect via [Ca(2+)](i) increase. Furthermore, erythrocytes oxidation induced with a free radical generator (APPH) showed effects in [Ca(2+)](i) and oxidative damage similar to those found in erythrocytes incubated with lead. Co-incubation with trolox prevents the oxidative effects induced by AAPH in erythrocytes. These results suggest that increase of [Ca(2+)](i) depends on the oxidative status of the erythrocytes incubated with lead. We consider that this model contributes in the understanding of the relation between oxidative damage induced by lead exposure and Ca(2+) homeostasis, the consequences related to these phenomena and the molecular basis of lead toxicity in no excitable cells.

  8. Effect of Plant Growth Regulators on Calcium-stimulated Serine Transport into Tobacco Cells

    PubMed Central

    Smith, Ivan K.

    1978-01-01

    The transport of serine into tobacco cells (Nicotiana tabacum L.) cultured in liquid medium was examined. Transport was inhibited approximately 50% by 2,4-dichlorophenoxyacetic acid, indoleacetic acid, α-naphthalene acetic acid, and kinetin at a concentration of 10 micrograms per milliliter. Transport was not inhibited by 2,6-dichlorophenoxyacetic acid and inhibited less than 25% by p-chlorophenoxyacetic acid at this concentration. Removal of 2,4-dichlorophenoxyacetic acid from the transport medium resulted in an alleviation of inhibition. Gibberellic acid at concentrations from 2 to 20 micrograms per milliliter stimulated transport. It was previously shown that inhibition of transport by La3+ was due to removal of Ca2+ from surface sites and inhibition of Ca2+ uptake by cells. None of the growth regulators tested had any significant effect on Ca2+ binding and/or transport. A contributing factor to the low transport rates in the absence of Ca2+ is the increased rate of serine efflux. None of the growth regulators tested had any significant effect on the rate of serine efflux. PMID:16660646

  9. Allergens stimulate store-operated calcium entry and cytokine production in airway epithelial cells

    PubMed Central

    Jairaman, Amit; Maguire, Chelsea H.; Schleimer, Robert P.; Prakriya, Murali

    2016-01-01

    Aberrant immune responses to environmental allergens including insect allergens from house dust mites and cockroaches contribute to allergic inflammatory diseases such as asthma in susceptible individuals. Airway epithelial cells (AECs) play a critical role in this process by sensing the proteolytic activity of allergens via protease-activated receptors (PAR2) to initiate inflammatory and immune responses in the airway. Elevation of cytosolic Ca2+ is an important signaling event in this process, yet the fundamental mechanism by which allergens induce Ca2+ elevations in AECs remains poorly understood. Here we find that extracts from dust mite and cockroach induce sustained Ca2+ elevations in AECs through the activation of Ca2+ release-activated Ca2+ (CRAC) channels encoded by Orai1 and STIM1. CRAC channel activation occurs, at least in part, through allergen mediated stimulation of PAR2 receptors. The ensuing Ca2+ entry then activates NFAT/calcineurin signaling to induce transcriptional production of the proinflammatory cytokines IL-6 and IL-8. These findings highlight a key role for CRAC channels as regulators of allergen induced inflammatory responses in the airway. PMID:27604412

  10. Allergens stimulate store-operated calcium entry and cytokine production in airway epithelial cells.

    PubMed

    Jairaman, Amit; Maguire, Chelsea H; Schleimer, Robert P; Prakriya, Murali

    2016-09-08

    Aberrant immune responses to environmental allergens including insect allergens from house dust mites and cockroaches contribute to allergic inflammatory diseases such as asthma in susceptible individuals. Airway epithelial cells (AECs) play a critical role in this process by sensing the proteolytic activity of allergens via protease-activated receptors (PAR2) to initiate inflammatory and immune responses in the airway. Elevation of cytosolic Ca(2+) is an important signaling event in this process, yet the fundamental mechanism by which allergens induce Ca(2+) elevations in AECs remains poorly understood. Here we find that extracts from dust mite and cockroach induce sustained Ca(2+) elevations in AECs through the activation of Ca(2+) release-activated Ca(2+) (CRAC) channels encoded by Orai1 and STIM1. CRAC channel activation occurs, at least in part, through allergen mediated stimulation of PAR2 receptors. The ensuing Ca(2+) entry then activates NFAT/calcineurin signaling to induce transcriptional production of the proinflammatory cytokines IL-6 and IL-8. These findings highlight a key role for CRAC channels as regulators of allergen induced inflammatory responses in the airway.

  11. Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

    NASA Astrophysics Data System (ADS)

    Zhang, Buhao; Xu, Xuhui; Li, Qianyue; Wu, Yumei; Qiu, Jianbei; Yu, Xue

    2014-09-01

    Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl2O4:Eu2+, R3+ (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R3+ ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl2O4:Eu2+. The greatly improved LPL performance was observed in Nd3+ co-doped samples, which indicates that the incorporation of Nd3+ creates suitable traps for LPL. While co-doping Tm3+ ions, the intensity of high temperature of thermoluminescence band in CaAl2O4:Eu2+ phosphors is enhanced for the formation of the most suitable traps which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R3+ ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl2O4:Eu2+, R3+ exhibits different read-in/read-out performance as well.

  12. Allergens stimulate store-operated calcium entry and cytokine production in airway epithelial cells.

    PubMed

    Jairaman, Amit; Maguire, Chelsea H; Schleimer, Robert P; Prakriya, Murali

    2016-01-01

    Aberrant immune responses to environmental allergens including insect allergens from house dust mites and cockroaches contribute to allergic inflammatory diseases such as asthma in susceptible individuals. Airway epithelial cells (AECs) play a critical role in this process by sensing the proteolytic activity of allergens via protease-activated receptors (PAR2) to initiate inflammatory and immune responses in the airway. Elevation of cytosolic Ca(2+) is an important signaling event in this process, yet the fundamental mechanism by which allergens induce Ca(2+) elevations in AECs remains poorly understood. Here we find that extracts from dust mite and cockroach induce sustained Ca(2+) elevations in AECs through the activation of Ca(2+) release-activated Ca(2+) (CRAC) channels encoded by Orai1 and STIM1. CRAC channel activation occurs, at least in part, through allergen mediated stimulation of PAR2 receptors. The ensuing Ca(2+) entry then activates NFAT/calcineurin signaling to induce transcriptional production of the proinflammatory cytokines IL-6 and IL-8. These findings highlight a key role for CRAC channels as regulators of allergen induced inflammatory responses in the airway. PMID:27604412

  13. Simultaneous control of Hg0, SO2, and NOx by novel oxidized calcium-based sorbents.

    PubMed

    Ghorishi, S Behrooz; Singer, Carl F; Jozewicz, Wojciech S; Sedman, Charles B; Srivastava, Ravi K

    2002-03-01

    Efforts to develop multipollutant control strategies have demonstrated that adding certain oxidants to different classes of Ca-based sorbents leads to a significant improvement in elemental Hg vapor (Hg0), SO2, and NOx removal from simulated flue gases. In the study presented here, two classes of Ca-based sorbents (hydrated limes and silicate compounds) were investigated. A number of oxidizing additives at different concentrations were used in the Ca-based sorbent production process. The Hg0, SO2, and NOx capture capacities of these oxidant-enriched sorbents were evaluated and compared to those of a commercially available activated carbon in bench-scale, fixed-bed, and fluid-bed systems. Calcium-based sorbents prepared with two oxidants, designated C and M, exhibited Hg0 sorption capacities (approximately 100 microg/g) comparable to that of the activated carbon; they showed far superior SO2 and NOx sorption capacities. Preliminary cost estimates for the process utilizing these novel sorbents indicate potential for substantial lowering of control costs, as compared with other processes currently used or considered for control of Hg0, SO2, and NOx emissions from coal-fired boilers. The implications of these findings toward development of multipollutant control technologies and planned pilot and field evaluations of more promising multipollutant sorbents are summarily discussed.

  14. Pharmacological analysis of signal transduction pathways required for oxidative burst in chicken heterophils stimulated by a Toll-like receptor 2 agonist.

    PubMed

    Farnell, Morgan B; He, Haiqi; Genovese, Kenneth; Kogut, Michael H

    2003-11-01

    Toll-like receptors (TLRs) play an important role in the innate immune response of avian heterophils. We previously used the pharmacological inhibitors genistein, verapamil, chelerythrine, and pertussis toxin to investigate the upstream signaling events involved in TLR2-mediated oxidative burst in chicken heterophils. Only chelerythrine, a protein kinase C inhibitor, was found to significantly inhibit oxidative burst stimulated by the TLR2 agonist lipoteichoic acid (LTA). In the present study, we used selective pharmacological inhibitors to investigate the roles of phosphatidylinositol-3'-kinase (PI3-K), phospholipase C (PLC), calcium-dependent protein kinase C (PKC), extra-cellular signal regulated kinase (ERK), and nuclear translocation factor kappa B (NF-kappaB) on TLR2-mediated oxidative burst. U-73122 (a PLC inhibitor), wortmannin (a PI3-K inhibitor), PD 98059 (an ERK inhibitor), Gö 6976 (a PKC inhibitor) and Bay 11-7082 (a NF-kappaB inhibitor) significantly decreased LTA-stimulated oxidative burst in heterophils by 77%, 30%, 36%, 78%, and 61%, respectively. Activated TLR2 utilizes PI3-K, PLC, PKC, ERK, and NF-kappaB as signaling factors that mediate the oxidative burst of chicken heterophils.

  15. Amplified RLR signaling activation through an interferon-stimulated gene-endoplasmic reticulum stress-mitochondrial calcium uniporter protein loop.

    PubMed

    Cheng, Jinbo; Liao, Yajin; Zhou, Lujun; Peng, Shengyi; Chen, Hong; Yuan, Zengqiang

    2016-01-01

    Type I interferon (IFN-I) is critical for a host against viral and bacterial infections via induction of hundreds of interferon-stimulated genes (ISGs), but the mechanism underlying the regulation of IFN-I remains largely unknown. In this study, we first demonstrate that ISG expression is required for optimal IFN-β levels, an effect that is further enhanced by endoplasmic reticulum (ER) stress. Furthermore, we identify mitochondrial calcium uniporter protein (MCU) as a mitochondrial antiviral signaling protein (MAVS)-interacting protein that is important for ER stress induction and amplified MAVS signaling activation. In addition, by performing an ectopic expression assay to screen a library of 117 human ISGs for effects on IFN-β levels, we found that tumor necrosis factor receptor 1 (TNFR1) significantly increases IFN-β levels independent of ER stress. Altogether, our findings suggest that MCU and TNFR1 are involved in the regulation of RIG-I-like receptors (RLR) signaling. PMID:26892273

  16. Silicate-substituted calcium phosphate with enhanced strut porosity stimulates osteogenic differentiation of human mesenchymal stem cells.

    PubMed

    De Godoy, Roberta Ferro; Hutchens, Stacy; Campion, Charlie; Blunn, Gordon

    2015-01-01

    While many synthetic ceramic bone graft substitutes (BGSs) have osteoconductive properties (e.g. provide a physical scaffold for osteointegration of surrounding bone tissue), certain BGSs are osteostimulative in that they actively upregulate mesenchymal stem cell proliferation and stimulate differentiation into osteoblast-like cells. The osteostimulative properties of silicate-substituted calcium phosphate with enhanced porosity (SiCaP EP) were evaluated in vitro with STRO-1+ immunoselected human bone marrow derived mesenchymal stem cells (HBMSCs). Osteostimulative materials (SiCaP) and Bioglass 45S5 (Bioglass) were also assessed as positive controls along with non-silicate substituted hydroxyapatite as a negative control. HBMSCs were also assessed on Thermanox discs cultured in basal and osteogenic media to determine when osteogenic differentiation could be significantly detected with this in vitro cell system. HBMSC viability and necrosis, total DNA content, alkaline phosphatase (ALP) expression, and osteocalcin expression were evaluated after 7, 14, 21, and 28 days. It was demonstrated that SiCaP EP is osteostimulative based on its propensity to support STRO-1+ HBMSC proliferation and ability to promote the differentiation of HBMSCs down the osteoblastic lineage from ALP-expressing, matrix-producing osteoblasts to Osteocalcin-producing pre-osteocytes without the presence of external osteogenic factors. SiCaP EP permitted greater HBMSC attachment as well as ALP and Osteocalcin expression than Bioglass which may be attributed to its microstructure and chemistry.

  17. In vitro electrical properties for iridium oxide versus titanium nitride stimulating electrodes.

    PubMed

    Weiland, James D; Anderson, David J; Humayun, Mark S

    2002-12-01

    Stimulating electrode materials must be capable of supplying high-density electrical charge to effectively activate neural tissue. Platinum is the most commonly used material for neural stimulation. Two other materials have been considered: iridium oxide and titanium nitride. This study directly compared the electrical characteristics of iridium oxide and titanium nitride by fabricating silicon substrate probes that differed only in the material used to form the electrode. Electrochemical measurements indicated that iridium oxide had lower impedance and a higher charge storage capacity than titanium nitride, suggesting better performance as a stimulating electrode. Direct measurement of the electrode potential in response to a biphasic current pulse confirmed that iridium oxide uses less voltage to transfer the same amount of charge, therefore using less power. The charge injection limit for titanium nitride was 0.87 mC/cm2, contradicting other reports estimating that titanium nitride was capable of injecting 22 mC/cm2. Iridium oxide charge storage was 4 mC/cm2, which is comparable to other published values for iridium oxide. Electrode efficiency will lead to an overall more efficient and effective device.

  18. Influence of addition of calcium oxide on physicochemical properties of Portland cement with zirconium or niobium oxide

    PubMed Central

    Tanomaru-Filho, Mario; Garcia, André Cresto; Bosso-Martelo, Roberta; Berbert, Fabio Luis Camargo V.; Nunes Reis, José Mauricio Santos; Guerreiro-Tanomaru, Juliane Maria

    2015-01-01

    Context: Calcium oxide (CaO) may be added to mineral trioxide aggregate (MTA) or Portland cement (PC) to improve physicochemical and biological properties. Aims: To evaluate the physicochemical properties of PC associated with radiopacifiers and CaO. Materials and Methods: MTA Angelus, PC + 30% zirconium oxide (Zr), or 30% niobium oxide (Nb) associated with 10 or 20% of CaO were evaluated. Gilmore needles were used to evaluate initial and final setting time. Compressive strength was evaluated after the periods of 24 hours and 21 days. pH was analyzed after 3, 12, 24 hours, 7, 14, 21 days. Solubility and flow tests were performed based on the ISO 6876. The data obtained were submitted to analysis of variance and Tukey tests (P ≤ 0.05). Results: The associations with 10% CaO showed greater strength that the associations with 20% CaO. The shortest initial setting time was observed for the association PC + Zr + 20% CaO and MTA. All the cements presented alkaline pH. The flow of all cements was similar. The highest solubility was found in the associations with 20% CaO. Conclusion: The addition of CaO to PC favored the alkaline property and the PC + Zr + 20% CaO presented setting time similar to MTA. PMID:25829686

  19. Calcium ion requirement for acetylcholine-stimulated breakdown of triphosphoinositide in rabbit iris smooth muscle.

    PubMed

    Akhtar, R A; Abdel-Latif, A A

    1978-03-01

    Previous studies from this laboratory have established that addition of acetylcholine (ACh) or norepinephrine to 32P-labeled rabbit iris smooth muscle increases significantly the breakdown of triphosphoinositide (TPI) and that these stimulatory effects are blocked by atropine and phentolamine, respectively. The present studies were undertaken in order to show the effect of Ca++ on the ACh-stimulated breakdown of TPI ("TPI effect") in this tissue. Paired iris smooth muscles were prelabeled with 32Pi for 30 minutes at 37 degrees C in Ca++-free iso-osmotic salt medium. The prelabeled irises were then washed and incubated for 10 minutes in nonradioactive Ca++-free medium which contained 10 mM 2-deoxyglucose under various conditions. The phospholipids were isolated by means of two-dimensional thin-layer chromatography and their radioactivities were determined. In the absence of Ca++, 50 micrometer ACh increased TPI breakdown and phosphatidic acid (PA) labeling by 16 and 38%, respectively. In the absence of ACh, 0.75 micrometer Ca++ increased TPI breakdown and PA labeling by 11 and 20%, respectively. When both ACh and Ca++ were added, the increase in TPI breakdown and PA labeling rose to 32 and 74%, respectively. The labeling of phosphatidylinositol was found to be insensitive to the presence of Ca++. Ca++ was determined in the iris smooth muscle and it was found to contain 3.13 mumol of Ca++ per g of tissue. This was reduced by 80% after the muscle was washed and incubated in a medium which contained 0.25 micrometer ethyleneglycol bis (beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA). The TPI effect was abolished by 0.25 micrometer EGTA and restored when excess Ca++ (1.25 micrometer) was added. Concentrations of Ca++ as low as 50 micrometer provoked a TPI effect. Sr++ (2 micrometer), but not Ba++ or Mn++, was found to substitute partially for Ca++. Ionophore A-23187 (20 micrometer) was found to increase the breakdown of TPI and labeling of PA by 11 and 24

  20. Stimulated arachidonate metabolism during foam cell transformation of mouse peritoneal macrophages with oxidized low density lipoprotein.

    PubMed Central

    Yokode, M; Kita, T; Kikawa, Y; Ogorochi, T; Narumiya, S; Kawai, C

    1988-01-01

    Changes in arachidonate metabolism were examined in mouse peritoneal macrophages incubated with various types of lipoproteins. Oxidized low density lipoprotein (LDL) was incorporated by macrophages and stimulated macrophage prostaglandin E2 (PGE2) and leukotriene C4 syntheses, respectively, 10.8- and 10.7-fold higher than by the control. Production of 6-keto-PGF1 alpha, a stable metabolite of prostacyclin, was also stimulated. No stimulation was found with native LDL, which was minimally incorporated by the cells. Acetylated LDL and beta-migrating very low density lipoprotein (beta-VLDL), though incorporated more efficiently than oxidized LDL, also had no stimulatory effect. When oxidized LDL was separated into the lipoprotein-lipid peroxide complex and free lipid peroxides, most of the stimulatory activity was found in the former fraction, indicating that stimulation of arachidonate metabolism in the cell is associated with uptake of the lipoprotein-lipid peroxide complex. These results suggest that peroxidative modification of LDL could contribute to the progression of atheroma by stimulating arachidonate metabolism during incorporation into macrophages. Images PMID:3125226

  1. Calcium, iron and neuronal function.

    PubMed

    Hidalgo, Cecilia; Núñez, Marco T

    2007-01-01

    Calcium and iron play dual roles in neuronal function: they are both essential but when present in excess they cause neuronal damage and may even induce neuronal death. Calcium signals are required for synaptic plasticity, a neuronal process that entails gene expression and which is presumably the cellular counterpart of cognitive brain functions such as learning and memory. Neuronal activity generates cytoplasmic and nuclear calcium signals that in turn stimulate pathways that promote the transcription of genes known to participate in synaptic plasticity. In addition, evidence discussed in this article shows that iron deficiency causes learning and memory impairments that persist following iron repletion, indicating that iron is necessary for normal development of cognitive functions. Recent results from our group indicate that iron is required for long-term potentiation in hippocampal CA1 neurons and that iron stimulates ryanodine receptor-mediated calcium release through ROS produced via the Fenton reaction leading to stimulation of the ERK signaling pathway. These combined results support a coordinated action between iron and calcium in synaptic plasticity and raise the possibility that elevated iron levels may contribute to neuronal degeneration through excessive intracellular calcium increase caused by iron-induced oxidative stress. PMID:17505966

  2. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No. 13169...(OH)2O2(Si2O5)3). 721.10018 Section 721.10018 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate...

  3. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No. 13169...(OH)2O2(Si2O5)3). 721.10018 Section 721.10018 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate...

  4. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No. 13169...(OH)2O2(Si2O5)3). 721.10018 Section 721.10018 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate...

  5. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No. 13169...(OH)2O2(Si2O5)3). 721.10018 Section 721.10018 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate...

  6. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No. 13169...(OH)2O2(Si2O5)3). 721.10018 Section 721.10018 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate...

  7. Magnesium supplementation through seaweed calcium extract rather than synthetic magnesium oxide improves femur bone mineral density and strength in ovariectomized rats.

    PubMed

    Bae, Yun Jung; Bu, So Young; Kim, Jae Young; Yeon, Jee-Young; Sohn, Eun-Wha; Jang, Ki-Hyo; Lee, Jae-Cheol; Kim, Mi-Hyun

    2011-12-01

    Commercially available seaweed calcium extract can supply high amounts of calcium as well as significant amounts of magnesium and other microminerals. The purpose of this study was to investigate the degree to which the high levels of magnesium in seaweed calcium extract affects the calcium balance and the bone status in ovariectomized rats in comparison to rats supplemented with calcium carbonate and magnesium oxide. A total of 40 Sprague-Dawley female rats (7 weeks) were divided into four groups and bred for 12 weeks: sham-operated group (Sham), ovariectomized group (OVX), ovariectomized with inorganic calcium and magnesium supplementation group (OVX-Mg), and ovariectomized with seaweed calcium and magnesium supplementation group (OVX-SCa). All experimental diets contained 0.5% calcium. The magnesium content in the experimental diet was 0.05% of the diet in the Sham and OVX groups and 0.1% of the diet in the OVX-Mg and OVX-SCa groups. In the calcium balance study, the OVX-Mg and OVX-SCa groups were not significantly different in calcium absorption compared to the OVX group. However, the femoral bone mineral density and strength of the OVX-SCa group were higher than those of the OVX-Mg and OVX groups. Seaweed calcium with magnesium supplementation or magnesium supplementation alone did not affect the serum ALP and CTx levels in ovariectomized rats. In summary, consumption of seaweed calcium extract or inorganic calcium carbonate with magnesium oxide demonstrated the same degree of intestinal calcium absorption, but only the consumption of seaweed calcium extract resulted in increased femoral bone mineral density and strength in ovariectomized rats. Our results suggest that seaweed calcium extract is an effective calcium and magnesium source for improving bone health compared to synthetic calcium and magnesium supplementation.

  8. Adsorption of superparamagnetic iron oxide nanoparticles on silica and calcium carbonate sand.

    PubMed

    Park, Yoonjee C; Paulsen, Jeffrey; Nap, Rikkert J; Whitaker, Ragnhild D; Mathiyazhagan, Vidhya; Song, Yi-Qiao; Hürlimann, Martin; Szleifer, Igal; Wong, Joyce Y

    2014-01-28

    Superparamagnetic iron oxide (SPIO) nanoparticles have the potential to be used in the characterization of porous rock formations in oil fields as a contrast agent for NMR logging because they are small enough to traverse through nanopores and enhance contrast by shortening NMR T2 relaxation time. However, successful development and application require detailed knowledge of particle stability and mobility in reservoir rocks. Because nanoparticle adsorption to sand (SiO2) and rock (often CaCO3) affects their mobility, we investigated the thermodynamic equilibrium adsorption behavior of citric acid-coated SPIO nanoparticles (CA SPIO NPs) and poly(ethylene glycol)-grafted SPIO nanoparticles (PEG SPIO NPs) on SiO2 (silica) and CaCO3 (calcium carbonate). Adsorption behavior was determined at various pH and salt conditions via chemical analysis and NMR, and the results were compared with molecular theory predictions. Most of the NPs were recovered from silica, whereas far fewer NPs were recovered from calcium carbonate because of differences in the mineral surface properties. NP adsorption increased with increasing salt concentration: this trend was qualitatively explained by molecular theory, as was the role of the PEG grafting in preventing NPs adsorption. Quantitative disagreement between the theoretical predictions and the data was due to NP aggregation, especially at high salt concentration and in the presence of calcium carbonate. Upon aggregation, NP concentrations as determined by NMR T2 were initially overestimated and subsequently corrected using the relaxation rate 1/T2, which is a function of aggregate size and fractal dimension of the aggregate. Our experimental validation of the theoretical predictions of NP adsorption to minerals in the absence of aggregation at various pH and salt conditions demonstrates that molecular theory can be used to determine interactions between NPs and relevant reservoir surfaces. Importantly, this integrated experimental and

  9. Mechanochemically Activated, Calcium Oxide-Based, Magnesium Oxide-Stabilized Carbon Dioxide Sorbents.

    PubMed

    Kurlov, Alexey; Broda, Marcin; Hosseini, Davood; Mitchell, Sharon J; Pérez-Ramírez, Javier; Müller, Christoph R

    2016-09-01

    Carbon dioxide capture and storage (CCS) is a promising approach to reduce anthropogenic CO2 emissions and mitigate climate change. However, the costs associated with the capture of CO2 using the currently available technology, that is, amine scrubbing, are considered prohibitive. In this context, the so-called calcium looping process, which relies on the reversible carbonation of CaO, is an attractive alternative. The main disadvantage of naturally occurring CaO-based CO2 sorbents, such as limestone, is their rapid deactivation caused by thermal sintering. Here, we report a scalable route based on wet mechanochemical activation to prepare MgO-stabilized, CaO-based CO2 sorbents. We optimized the synthesis conditions through a fundamental understanding of the underlying stabilization mechanism, and the quantity of MgO required to stabilize CaO could be reduced to as little as 15 wt %. This allowed the preparation of CO2 sorbents that exceed the CO2 uptake of the reference limestone by 200 %. PMID:27529608

  10. Mechanochemically Activated, Calcium Oxide-Based, Magnesium Oxide-Stabilized Carbon Dioxide Sorbents.

    PubMed

    Kurlov, Alexey; Broda, Marcin; Hosseini, Davood; Mitchell, Sharon J; Pérez-Ramírez, Javier; Müller, Christoph R

    2016-09-01

    Carbon dioxide capture and storage (CCS) is a promising approach to reduce anthropogenic CO2 emissions and mitigate climate change. However, the costs associated with the capture of CO2 using the currently available technology, that is, amine scrubbing, are considered prohibitive. In this context, the so-called calcium looping process, which relies on the reversible carbonation of CaO, is an attractive alternative. The main disadvantage of naturally occurring CaO-based CO2 sorbents, such as limestone, is their rapid deactivation caused by thermal sintering. Here, we report a scalable route based on wet mechanochemical activation to prepare MgO-stabilized, CaO-based CO2 sorbents. We optimized the synthesis conditions through a fundamental understanding of the underlying stabilization mechanism, and the quantity of MgO required to stabilize CaO could be reduced to as little as 15 wt %. This allowed the preparation of CO2 sorbents that exceed the CO2 uptake of the reference limestone by 200 %.

  11. Glutathione depletion exacerbates impairment by oxidative stress of phosphoinositide hydrolysis, AP-1, and NF-kappaB activation by cholinergic stimulation.

    PubMed

    Li, X; Song, L; Jope, R S

    1998-01-01

    Oxidative stress appears to contribute to neuronal dysfunction associated with Alzheimer's disease and other CNS neurodegenerative disorders. This investigation examined if oxidative stress might contribute to impairments in cholinergic receptor-linked signaling systems and if intracellular glutathione levels modulated responses to oxidative stress. To do this the activation of the AP-1 and NF-kappaB transcription factors and of the phosphoinositide second-messenger system was measured in human neuroblastoma SH-SY5Y cells after exposure to the oxidants H2O2 or diamide, with or without prior depletion of cellular glutathione. H2O2 concentration-dependently inhibited carbachol-stimulated AP-1 activation and this inhibition was potentiated in glutathione-depleted cells. Carbachol-stimulated NF-kappaB activation was unaffected by H2O2 unless glutathione was depleted, in which case there was a H2O2 concentration-dependent inhibition. Glutathione depletion also potentiated the inhibition by H2O2 of carbachol- or G-protein (NaF)-stimulated phosphoinositide hydrolysis, whereas phospholipase C activated by the calcium ionophore ionomycin was not inhibited. The thiol-oxidizing agent diamide also inhibited phosphoinositide hydrolysis stimulated by carbachol or NaF, and glutathione depletion potentiated the diamide concentration-dependent inhibition. Unlike H2O2, diamide also inhibited ionomycin-stimulated phosphoinositide hydrolysis. Activation of both AP-1 and NF-kappaB stimulated by carbachol was inhibited by diamide, and glutathione depletion potentiated the inhibitory effects of diamide. Thus, diamide inhibited a wider range of signaling processes than did H2O2, but glutathione depletion increased the susceptibility of phosphoinositide hydrolysis and of transcription factor activation to inhibition by both H2O2 and diamide. These results demonstrate that the vulnerability of signaling systems to oxidative stress is influenced by intracellular glutathione levels

  12. Influence of calcium sources on microbially induced calcium carbonate precipitation by Bacillus sp. CR2.

    PubMed

    Achal, Varenyam; Pan, Xiangliang

    2014-05-01

    Stimulation of microbially induced calcium carbonate precipitation (MICCP) is likely to be influenced by calcium sources. In order to study such influences, we performed MICCP using Bacillus sp. CR2 in nutrient broth containing urea, supplemented with different calcium sources (calcium chloride, calcium oxide, calcium acetate and calcium nitrate). The experiment lasted 7 days, during which bacterial growth, urease activity, calcite production and pH were measured. Our results showed that calcium chloride is the better calcium source for MICCP process, since it provides higher urease activity and more calcite production. The influences of calcium sources on MICCP were further studied using Fourier transform-infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. These analyses confirmed that the precipitate formed was CaCO3 and composed of predominantly calcite crystals with a little amount of aragonite and vaterite crystals. The maximum yield of calcite precipitation was achievable with calcium chloride followed by calcium nitrate as a calcium source. The results of present study may be applicable to media preparation during efficient MICCP process.

  13. Calcium-activated potassium channels mask vascular dysfunction associated with oxidized LDL exposure in rabbit aorta.

    PubMed

    Bocker, J M; Miller, F J; Oltman, C L; Chappell, D A; Gutterman, D D

    2001-05-01

    Endothelium-dependent vasodilation is impaired in atherosclerosis. Oxidized low density lipoprotein (ox-LDL) plays an important role, possibly through alterations in G-protein activation. We examined the effect of acute exposure to ox-LDL on the dilator responses of isolated rabbit aorta segments. We sought also to evaluate the specificity of this dysfunction for dilator stimuli that traditionally operate through a Gi-protein mechanism. Aortic segments were prepared for measurement of isometric tension. After contraction with prostaglandin F2alpha, relaxation to thrombin, adenosine diphosphate (ADP), or the endothelium-independent agonists, sodium nitroprusside (SNP) or papaverine was examined. Maximal relaxation to thrombin was impaired in the presence of ox-LDL (17.7+/-3.7% p<0.05) compared to control (no LDL) (52.6+/-4.0%). Ox-LDL did not affect maximal relaxation to ADP or SNP. However, in the presence of charybdotoxin (CHTX: calcium-activated potassium channel inhibitor) ox-LDL impaired relaxation to ADP (17.4+/-3.2%). CHTX did not affect control (no LDL) responses to ADP (69.6+/-5.0%) or relaxation to thrombin or papaverine. In conclusion, ox-LDL impairs relaxation to thrombin, but in the case of ADP, calcium-activated potassium channels compensate to maintain this relaxation. PMID:11605770

  14. Noscapine protects OLN-93 oligodendrocytes from ischemia-reperfusion damage: Calcium and nitric oxide involvement.

    PubMed

    Nadjafi, S; Ebrahimi, S-A; Rahbar-Roshandel, N

    2015-12-01

    This study was carried out to evaluate the effects of noscapine, a benzylisoquinoline alkaloid from opium poppy, on oligodendrocyte during ischemia/reperfusion-induced excitotoxic injury. Changes in intracellular calcium levels due to chemical ischemia and nitric oxide (NO) production during ischemia/reperfusion were evaluated as the hallmarks of ischemia-derived excitotoxic event. OLN-93 cell line (a permanent immature rat oligodendrocyte) was used as a model of oligodendrocyte. 30- or 60-minute-oxygen-glucose deprivation/24 hours reperfusion were used to induce excitotoxicity. MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay was used to evaluate cell viability. Ratiometric fluorescence microscopy using Ca(2+)-sensitive indicator Fura-2/AM was utilized to assess intracellular calcium levels. NO production was evaluated by Griess method. Noscapine (4 μM) significantly attenuated intracellular Ca(2+) elevation (P < 0.001). Also, noscapine significantly decreased NO production during a 30-minute oxygen-glucose deprivation/reperfusion (P < 0.01). The inhibitory effect of noscapine (4 μM) on intracellular Ca(2+) was greater than ionotropic glutamate receptors antagonists. Noscapine is protective against ischemia/reperfusion-induced excitotoxic injury in OLN-93 oligodendrocyte. This protective effect seems to be related to attenuation of intracellular Ca(2+) overload and NO production. PMID:26690027

  15. Characterization of calcium phosphate deposited on valve metal by anodic oxidation with polarity inversion.

    PubMed

    Okawa, Seigo; Homma, Kikuo; Kanatani, Mitsugu; Watanabe, Kouichi

    2009-07-01

    Electrochemical deposition of calcium phosphate (CAP) on valve metals such as Ta, Nb, and Zr, was performed by anodic oxidation with alternate polarity inversion at an applied 20 VDC. A saturated hydroxyapatite(HAP)-phosphoric acid solution (pH 3) was used as the electrolyte. FTIR, XRD, and XPS were employed to investigate the detailed characteristics of the deposition. HAP was precipitated on Ta; HAP including brushite and monetite on Nb; and HAP and monetite on Zr. The Ca/P atomic ratios were 1.3-1.5 by XPS, and HPO(4)(2- )bands were detected on Ta by FTIR. Therefore, the HAP precipitated on Ta was a Ca-deficient HAP. In addition, the XPS spectra of the specimens showed that phosphate ions were incorporated into the anodic oxide film. Deposits with nano-grain size were observed by AFM. The results confirmed that CAP with nano-grain size was deposited on valve metals by the anodic oxidation with polarity inversion. PMID:19721291

  16. Polyaniline-graphene oxide nanocomposite sensor for quantification of calcium channel blocker levamlodipine.

    PubMed

    Jain, Rajeev; Sinha, Ankita; Khan, Ab Lateef

    2016-08-01

    A novel polyaniline-graphene oxide nanocomposite (PANI/GO/GCE) sensor has been fabricated for quantification of a calcium channel blocker drug levamlodipine (LAMP). Fabricated sensor has been characterized by electrochemical impedance spectroscopy, square wave and cyclic voltammetry, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The developed PANI/GO/GCE sensor has excellent analytical performance towards electrocatalytic oxidation as compared to PANI/GCE, GO/GCE and bare GCE. Under optimized experimental conditions, the fabricated sensor exhibits a linear response for LAMP for its oxidation over a concentration range from 1.25μgmL(-1) to 13.25μgmL(-1) with correlation coefficient of 0.9950 (r(2)), detection limit of 1.07ngmL(-1) and quantification limit of 3.57ngmL(-1). The sensor shows an excellent performance for detecting LAMP with reproducibility of 2.78% relative standard deviation (RSD). The proposed method has been successfully applied for LAMP determination in pharmaceutical formulation with a recovery from 99.88% to 101.75%.

  17. Xiaokening stimulates endothelial nitric oxide release in diabetic rats

    PubMed Central

    Liu, Hong; Liu, Lei; Wei, Qunli; Cui, Jie; Yan, Changdong; Wang, Xin; Wu, Yongping

    2015-01-01

    INTRODUCTION Diabetes mellitus induces microangiopathic changes that lead to endothelial dysfunction. This study investigated the effect of Xiaokening, a type of Chinese compound medicine, on the mesenteric arteriolar endothelial cell function of diabetic rats and its underlying mechanism. METHODS Diabetes mellitus was induced in rat models via intraperitoneal injection of 60 mg/kg streptozotocin and observed over three weeks. Mesenteric arterioles, which were isolated in a cannulated and pressurised state, were incubated with intravascular injections of 1, 3 or 5 g/L Xiaokening for 24, 48 or 72 hours. The effects of Xiaokening on the release of nitric oxide (NO) on the mesenteric arterioles were detected under shear stress of 1, 10 and 20 dyn/cm2. Biochemical methods were used to determine the activities of superoxide dismutase (SOD) and xanthine oxidase (XO). The expressions of endothelial NO synthase (eNOS), SOD and XO in the mesenteric arterioles were assessed using Western blot. RESULTS Compared to normal rat arterioles, less NO was released in the mesenteric arterioles of diabetic rats. Xiaokening was found to have a concentration- and time-dependent effect on NO release; when the shear stress was increased, there was a gradual increase in the release of NO. Compared to normal arterioles, the expression of eNOS in the mesenteric arterioles of diabetic rats was lower. Incubation with Xiaokening increased SOD activity and expression, and decreased XO activity and expression in the mesenteric arterioles of the diabetic rats. CONCLUSION Xiaokening was able to significantly increase NO release and improve the endothelial function of mesenteric arterioles through antioxidative mechanisms. PMID:26243977

  18. Corrosion behavior of silicon nitride, magnesium oxide, and several metals in molten calcium chloride with chlorine

    SciTech Connect

    McLaughlin, D. . Research and Development Center); Sesions, C.E.; Marra, J.E. )

    1992-08-01

    In this paper corrosion studies are described in a molten calcium chloride environment sparged with chlorine gas at 850{degrees}C, both in the melt and in the gas phase above the salt, in support of efforts at Westinghouse Savannah River Company to develop more resistant materials of construction for molten salt processing of plutonium. Corrosion rates and electron microscope analyses are reported for Inconel alloys 601 and 617, tantalum, tungsten, magnesium oxide, and silicon nitride. Silicon nitride exhibited the greatest resistance, showing {lt}0.1 mg/cm{sup 2} {center dot} h loss in both melt and vapor None of the metallic coupons withstood the chlorine vapor environment, although Inconel indicated resistance immersed in the melt if protected from chlorine gas.

  19. Soybean beta 51-63 peptide stimulates cholecystokinin secretion via a calcium-sensing receptor in enteroendocrine STC-1 cells.

    PubMed

    Nakajima, Shingo; Hira, Tohru; Eto, Yuzuru; Asano, Kozo; Hara, Hiroshi

    2010-01-01

    We previously demonstrated that intraduodenal administration of an arginine-rich beta 51-63 peptide in soybean beta-conglycinin suppresses food intake via cholecystokinin (CCK) secretion in rats. However, the cellular mechanisms by which the beta 51-63 peptide induces CCK secretion remain to be clarified. In the present study, we examined whether the extracellular calcium-sensing receptor (CaR) mediates beta 51-63-induced CCK secretion in murine CCK-producing enteroendocrine cell line STC-1. CCK secretion and changes in intracellular Ca(2+) concentration in response to beta 51-63 peptide were measured in STC-1 cells under various extracellular Ca(2+) concentrations and after treatment with a CaR antagonist. Intracellular Ca(2+) concentrations in response to beta 51-63 peptide and extracellular Ca(2+) were also measured in CaR-expressing human embryonic kidney (HEK-293) cells. The beta 51-63 peptide induced CCK secretion and intracellular Ca(2+) mobilization in STC-1 cells under normal (1.2mM) extracellular Ca(2+) conditions in a dose-dependent manner. These responses to beta 51-63 peptide were reduced by the removal of intra- or extracellular Ca(2+) but enhanced by increasing extracellular Ca(2+) concentrations. Intracellular Ca(2+) mobilization induced by extracellular Ca(2+) was also increased by the pretreatment with beta 51-63 peptide. Treatment with a specific CaR antagonist (NPS2143) inhibited beta 51-63-induced CCK secretion and intracellular Ca(2+) mobilization. In addition, HEK-293 cells transfected with CaR acquired sensitivity to the beta 51-63 peptide. From these results, we conclude that CaR is the beta 51-63 peptide sensor responsible for the stimulation of CCK secretion in enteroendocrine STC-1 cells.

  20. Bile acids stimulate chloride secretion through CFTR and calcium-activated Cl- channels in Calu-3 airway epithelial cells.

    PubMed

    Hendrick, Siobhán M; Mroz, Magdalena S; Greene, Catherine M; Keely, Stephen J; Harvey, Brian J

    2014-09-01

    Bile acids resulting from the aspiration of gastroesophageal refluxate are often present in the lower airways of people with cystic fibrosis and other respiratory distress diseases. Surprisingly, there is little or no information on the modulation of airway epithelial ion transport by bile acids. The secretory effect of a variety of conjugated and unconjugated secondary bile acids was investigated in Calu-3 airway epithelial cells grown under an air-liquid interface and mounted in Ussing chambers. Electrogenic transepithelial ion transport was measured as short-circuit current (Isc). The taurine-conjugated secondary bile acid, taurodeoxycholic acid (TDCA), was found to be the most potent modulator of basal ion transport. Acute treatment (5 min) of Calu-3 cells with TDCA (25 μM) on the basolateral side caused a stimulation of Isc, and removal of extracellular Cl(-) abolished this response. TDCA produced an increase in the cystic fibrosis transmembrane conductance regulator (CFTR)-dependent current that was abolished by pretreatment with the CFTR inhibitor CFTRinh172. TDCA treatment also increased Cl(-) secretion through calcium-activated chloride (CaCC) channels and increased the Na(+)/K(+) pump current. Acute treatment with TDCA resulted in a rapid cellular influx of Ca(2+) and increased cAMP levels in Calu-3 cells. Bile acid receptor-selective activation with INT-777 revealed TGR5 localized at the basolateral membrane as the receptor involved in TDCA-induced Cl(-) secretion. In summary, we demonstrate for the first time that low concentrations of bile acids can modulate Cl(-) secretion in airway epithelial cells, and this effect is dependent on both the duration and sidedness of exposure to the bile acid.

  1. Nitric oxide donors, sodium nitroprusside and S-nitroso-N-acetylpencillamine, stimulate myoblast proliferation in vitro

    NASA Technical Reports Server (NTRS)

    Ulibarri, J. A.; Mozdziak, P. E.; Schultz, E.; Cook, C.; Best, T. M.

    1999-01-01

    Nitric oxide (NO) is an inter- and intracellular messenger involved in a variety of physiologic and pathophysiologic conditions. The effect of two NO donors, sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) and their effect on myoblast proliferation was examined. Both donors stimulated an increase in myoblast cell number over a range (1-10 microM) of donor concentrations. However, 50 microM SNAP inhibited myoblast proliferation. Cell numbers from cultures treated with degraded 10 microM SNAP were equivalent to the control. Therefore, it appears NO can stimulate as well as inhibit myoblast proliferation.

  2. Role of skeletal muscle mitochondrial density on exercise-stimulated lipid oxidation.

    PubMed

    Galgani, Jose E; Johannsen, Neil M; Bajpeyi, Sudip; Costford, Sheila R; Zhang, Zhengyu; Gupta, Alok K; Ravussin, Eric

    2012-07-01

    Reduced skeletal muscle mitochondrial density is proposed to lead to impaired muscle lipid oxidation and increased lipid accumulation in sedentary individuals. We assessed exercise-stimulated lipid oxidation by imposing a prolonged moderate-intensity exercise in men with variable skeletal muscle mitochondrial density as measured by citrate synthase (CS) activity. After a 2-day isoenergetic high-fat diet, lipid oxidation was measured before and during exercise (650 kcal at 50% VO(2)max) in 20 healthy men with either high (HI-CS = 24 ± 1; mean ± s.e.) or low (LO-CS = 17 ± 1 nmol/min/mg protein) muscle CS activity. Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Respiratory exchange data and blood samples were collected at rest and throughout the exercise. HI-CS subjects had higher VO(2)max (50 ± 1 vs. 44 ± 2 ml/kg fat free mass/min; P = 0.01), lower fasting respiratory quotient (RQ) (0.81 ± 0.01 vs. 0.85 ± 0.01; P = 0.04) and higher ex vivo muscle palmitate oxidation (866 ± 168 vs. 482 ± 78 nmol/h/mg muscle; P = 0.05) compared to LO-CS individuals. However, whole-body exercise-stimulated lipid oxidation (20 ± 2 g vs. 19 ± 1 g; P = 0.65) and plasma glucose, lactate, insulin, and catecholamine responses were similar between the two groups. In conclusion, in response to the same energy demand during a moderate prolonged exercise bout, reliance on lipid oxidation was similar in individuals with high and low skeletal muscle mitochondrial density. This data suggests that decreased muscle mitochondrial density may not necessarily impair reliance on lipid oxidation over the course of the day since it was normal under a high-lipid oxidative demand condition. Twenty-four-hour lipid oxidation and its relationship with mitochondrial density need to be assessed. PMID:21681225

  3. Electrocatalytic Properties of Nanocrystalline Calcium-Doped Lanthanum Cobalt Oxide for Bifunctional Oxygen Electrodes

    SciTech Connect

    Malkhandi, S; Yang, B; Manohar, AK; Manivannan, A; Prakash, GKS; Narayanan, SR

    2012-04-19

    Calcium-doped lanthanum cobalt oxide is a promising electrocatalyst for oxygen evolution and oxygen reduction in rechargeable metal air batteries and water electrolyzers operating with alkaline electrolyte. Nanocrystalline perovskite of composition La0.6Ca0.4CoO3 with a unique cellular internal structure was prepared at 350 degrees C and then annealed in air at progressively higher temperatures in the range of 600-750 degrees C. The samples were characterized by electrochemical techniques and X-ray photoelectron spectroscopy. The area-specific electrocatalytic activity for oxygen evolution/oxygen reduction, the oxidation state of cobalt, and the crystallite size increased with annealing temperature, while the Tafel slope remained constant. These trends provide new insights into the role of the cobalt center in oxygen evolution and oxygen reduction, and how preparation conditions can be altered to tune the activity of the cobalt center for electrocatalysis. We expect these findings to guide the design of electrocatalysts for bifunctional oxygen electrodes, in general.

  4. Odontogenic effects of a fast-setting calcium-silicate cement containing zirconium oxide.

    PubMed

    Kim, Kyoung-A; Yang, Yeon-Mi; Kwon, Young-Sun; Hwang, Yun-Chan; Yu, Mi-Kyung; Min, Kyung-San

    2015-01-01

    A fast-setting calcium-silicate cement (Endocem) was introduced in the field of dentistry for use in vital pulp therapy. Similar to mineral trioxide aggregate (MTA), it contains bismuth oxide to provide radiopacity. Recently, another product, EndocemZr, which contains zirconium oxide (ZrO2) as a radiopacifier, was developed by the same company. In this study, the biological/odontogenic effects of EndocemZr were investigated in human primary dental pulp cells (hpDPCs) in vitro and on capped rat teeth in vivo. The biocompatibility of EndocemZr was similar to that of ProRoot and Endocem on the basis of cell viability tests and cell morphological analysis. The mineralization nodule formation, expression of odontogenic-related markers, and reparative dentin formation of EndocemZr group was similar to those of other material groups. Our results suggest that EndocemZr has the potential to be used as an effective material for vital pulp therapy, similar to ProRoot and Endocem.

  5. [Effect of calcium cations on acid-base properties and free radical oxidation of dopamine and pyrocatechol].

    PubMed

    Lebedev, A V; Ivanova, M V; Timoshin, A A; Ruuge, E K

    2008-01-01

    Ca2+-induced increase in the rate of pyrocatechol and dopamine oxidation by dioxygen and Ca2+-dependent acid-base properties of the catechols were studied by potentiometric titration, UV/Vis-spectrophotometry, EPR-spectroscopy, and by measurement of oxygen consumption. The effect of Ca2+ on the chain reactions of oxidation can be explained by additional deprotonation (decrease in pKai) of the catechols that accelerates one electron transport to dioxygen and formation of calcium semiquinonate, undergoing further oxidation. The described Ca2+-dependent redox-conversion of ortho-phenols proposes that an additional function of calcium in the cell can be its involvement in free radical oxidoreductive reactions at pH > pKai.

  6. Chitosan-modified cobalt oxide nanoparticles stimulate TNF-α-mediated apoptosis in human leukemic cells.

    PubMed

    Chattopadhyay, Sourav; Dash, Sandeep Kumar; Kar Mahapatra, Santanu; Tripathy, Satyajit; Ghosh, Totan; Das, Balaram; Das, Debasis; Pramanik, Panchanan; Roy, Somenath

    2014-03-01

    The objective of this study was to develop chitosan-based delivery of cobalt oxide nanoparticles to human leukemic cells and investigate their specific induction of apoptosis. The physicochemical properties of the chitosan-coated cobalt oxide nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, X-ray diffraction, and Fourier transform infrared spectroscopy. The solubility of chitosan-coated cobalt oxide nanoparticles was higher at acidic pH, which helps to release more cobalt ions into the medium. Chitosan-coated cobalt oxide nanoparticles showed good compatibility with normal cells. However, our results showed that exposure of leukemic cells (Jurkat cells) to chitosan-coated cobalt oxide nanoparticles caused an increase in reactive oxygen species generation that was abolished by pretreatment of cells with the reactive oxygen species scavenger N-acetyl-L-cysteine. The apoptosis of Jurkat cells was confirmed by flow-cytometric analysis. Induction of TNF-α secretion was observed from stimulation of Jurkat cells with chitosan-coated cobalt oxide nanoparticles. We also tested the role of TNF-α in the induction of Jurkat cell death in the presence of TNF-α and caspase inhibitors. Treatment of leukemic cells with a blocker had a greater effect on cancer cell viability. From our findings, oxidative stress and caspase activation are involved in cancer cell death induced by chitosan-coated cobalt oxide nanoparticles.

  7. CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

    PubMed

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-09-01

    A specialized culture medium termed ciliary neurotrophic factor-treated astrocyte-conditioned medium (CNTF-ACM) allows investigators to assess the peripheral effects of CNTF-induced activated astrocytes upon cultured neurons. CNTF-ACM has been shown to upregulate neuronal L-type calcium channel current activity, which has been previously linked to changes in mitochondrial respiration and oxidative stress. Therefore, the aim of this study was to evaluate CNTF-ACM's effects upon mitochondrial respiration and oxidative stress in rat cortical neurons. Cortical neurons, CNTF-ACM, and untreated control astrocyte-conditioned medium (UC-ACM) were prepared from neonatal Sprague-Dawley rat cortical tissue. Neurons were cultured in either CNTF-ACM or UC-ACM for a 48-h period. Changes in the following parameters before and after treatment with the L-type calcium channel blocker isradipine were assessed: (i) intracellular calcium levels, (ii) mitochondrial membrane potential (ΔΨm), (iii) oxygen consumption rate (OCR) and adenosine triphosphate (ATP) formation, (iv) intracellular nitric oxide (NO) levels, (v) mitochondrial reactive oxygen species (ROS) production, and (vi) susceptibility to the mitochondrial complex I toxin rotenone. CNTF-ACM neurons displayed the following significant changes relative to UC-ACM neurons: (i) increased intracellular calcium levels (p < 0.05), (ii) elevation in ΔΨm (p < 0.05), (iii) increased OCR and ATP formation (p < 0.05), (iv) increased intracellular NO levels (p < 0.05), (v) increased mitochondrial ROS production (p < 0.05), and (vi) increased susceptibility to rotenone (p < 0.05). Treatment with isradipine was able to partially rescue these negative effects of CNTF-ACM (p < 0.05). CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity. PMID:27514537

  8. Improved sugar cane juice clarification by understanding calcium oxide-phosphate-sucrose systems.

    PubMed

    Doherty, William O S

    2011-03-01

    It is accepted that the efficiency of sugar cane clarification is closely linked with sugar juice composition (including suspended or insoluble impurities), the inorganic phosphate content, the liming condition and type, and the interactions between the juice components. These interactions are not well understood, particularly those between calcium, phosphate, and sucrose in sugar cane juice. Studies have been conducted on calcium oxide (CaO)/phosphate/sucrose systems in both synthetic and factory juices to provide further information on the defecation process (i.e., simple liming to effect impurity removal) and to identify an effective clarification process that would result in reduced scaling of sugar factory evaporators, pans, and centrifugals. Results have shown that a two-stage process involving the addition of lime saccharate to a set juice pH followed by the addition of sodium hydroxide to a final juice pH or a similar two-stage process where the order of addition of the alkalis is reversed prior to clarification reduces the impurity loading of the clarified juice compared to that of the clarified juice obtained by the conventional defecation process. The treatment process showed reductions in CaO (27% to 50%) and MgO (up to 20%) in clarified juices with no apparent loss in juice clarity or increase in residence time of the mud particles compared to those in the conventional process. There was also a reduction in the SiO2 content. However, the disadvantage of this process is the significant increase in the Na2O content.

  9. Electron-Stimulated Oxidation of Thin Water Films Adsorbed on TiO2(110)

    SciTech Connect

    Lane, Christopher D.; Petrik, Nikolay G.; Orlando, Thomas M.; Kimmel, Greg A.

    2007-11-08

    Electron-stimulated reactions in thin (< 3 monolayer, ML) water films adsorbed on TiO2(110) are investigated. For electron fluences less than ~1×1016 e-/cm2, irradiation with 100 eV electrons results in electron-stimulated desorption (ESD) of atomic and molecular hydrogen, but no measurable O2. The ESD leaves adsorbed hydroxyls which oxidize the TiO2(110) surface and change the post-irradiation TPD spectra of the remaining water in characteristic ways. The species remaining on the TiO2(110) after irradiation of adsorbed water films are apparently similar to those produced without irradiation by co-dosing water and O2. Annealing above ~600 K reduces the oxidized surfaces, and water TPD spectra characteristic of ion sputtered and annealed TiO2(110) are recovered. The rate of electron-stimulated “oxidation” of the water films is proportional to the coverage of water in the first layer for coverages less than 1 ML. However, higher coverages suppress this reaction. When thin water films are irradiated, the rate of electron-stimulated oxidation is independent of the initial oxygen vacancy concentration, as is the final oxidized state achieved at high electron fluences. To explain the results, we propose that electron excitation of water molecules adsorbed on Ti4+ sites leads to desorption of hydrogen atoms and leaves an OH adsorbed at the site. If hydroxyls are present in the bridging oxygen rows, these react with the OH’s on the Ti4+ sites to reform water and heal the oxygen vacancy associated with the bridging OH. Once the bridge bonded hydroxyls have been eliminated, further irradiation increases the concentration of OH’s in the Ti4+ rows leading to the creation of species which block sites in the Ti4+ rows, perhaps H2O2 and/or HO2.

  10. Dipterinyl Calcium Pentahydrate Inhibits Intracellular Mycobacterial Growth in Human Monocytes via the C-C Chemokine MIP-1β and Nitric Oxide

    PubMed Central

    Sakala, Isaac G.; Eickhoff, Christopher S.; Blazevic, Azra; Moheno, Phillip; Silver, Richard F.

    2013-01-01

    Tuberculosis remains one of the top three leading causes of morbidity and mortality worldwide, complicated by the emergence of drug-resistant Mycobacterium tuberculosis strains and high rates of HIV coinfection. It is important to develop new antimycobacterial drugs and immunomodulatory therapeutics and compounds that enhance antituberculous immunity. Dipterinyl calcium pentahydrate (DCP), a calcium-complexed pterin compound, has previously been shown to inhibit human breast cancer cells and hepatitis B virus (HBV). DCP inhibitory effects were attributed to induction of apoptosis and/or increased production of interleukin 12 (IL-12) and granulocyte-macrophage colony-stimulating factor (GM-CSF). In this study, we tested the ability of DCP to mediate inhibition of intracellular mycobacteria within human monocytes. DCP treatment of infected monocytes resulted in a significant reduction in viability of intracellular but not extracellular Mycobacterium bovis BCG. The antimicrobial activity of DCP was comparable to that of pyrazinamide (PZA), one of the first-line antituberculosis drugs currently used. DCP potentiated monocyte antimycobacterial activity by induction of the cysteine-cysteine (C-C) chemokine macrophage inflammatory protein 1β (MIP-1β) and inducible nitric oxide synthase 2. Addition of human anti-MIP-1β neutralizing antibody or a specific inhibitor of the l-arginase-nitric oxide pathway (NG-monomethyl l-arginine [l-NMMA] monoacetate) reversed the inhibitory effects of DCP on intracellular mycobacterial growth. These findings indicate that DCP induced mycobacterial killing via MIP-1β- and nitric oxide-dependent effects. Hence, DCP acts as an immunoregulatory compound enhancing the antimycobacterial activity of human monocytes. PMID:23509148

  11. Asymmetric Dimethylarginine Blocks Nitric Oxide-Mediated Alcohol-Stimulated Cilia Beating

    PubMed Central

    Wyatt, T. A.; Wells, S. M.; Alsaidi, Z. A.; DeVasure, J. M.; Klein, E. B.; Bailey, K. L.; Sisson, J. H.

    2013-01-01

    The airway epithelium is exposed to alcohol during drinking through direct exhalation of volatized ethanol from the bronchial circulation. Alcohol exposure leads to a rapid increase in the cilia beat frequency (CBF) of bronchial epithelial cells followed by a chronic desensitization of cilia stimulatory responses. This effect is governed in part by the nitric oxide regulation of cyclic guanosine and adenosine monophosphate-dependent protein kinases (PKG and PKA) and is not fully understood. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is implicated in the pathogenesis of several pulmonary disorders. We hypothesized that the inhibition of nitric oxide synthase by ADMA blocks alcohol-stimulated increases in CBF. To test this hypothesis, ciliated primary bovine bronchial epithelial cells (BBEC) were preincubated with ADMA (100 µM) and stimulated with 100 mM ethanol. CBF was measured and PKA assayed. By 1 hr, ethanol activated PKA, resulting in elevated CBF. Both alcohol-induced PKA activation and CBF were inhibited in the presence of ADMA. ADMA alone had no effect on PKA activity or CBF. Using a mouse model overexpressing the ADMA-degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH), we examined PKA and CBF in precision-cut mouse lung slices. Alcohol-stimulated increases in lung slice PKA and CBF were temporally enhanced in the DDAH mice versus control mice. PMID:24307761

  12. Magnetically stimulated ciprofloxacin release from polymeric microspheres entrapping iron oxide nanoparticles

    PubMed Central

    Sirivisoot, Sirinrath; Harrison, Benjamin S

    2015-01-01

    To extend the external control capability of drug release, iron oxide nanoparticles (NPs) encapsulated into polymeric microspheres were used as magnetic media to stimulate drug release using an alternating magnetic field. Chemically synthesized iron oxide NPs, maghemite or hematite, and the antibiotic ciprofloxacin were encapsulated together within polycaprolactone microspheres. The polycaprolactone microspheres entrapping ciprofloxacin and magnetic NPs could be triggered for immediate drug release by magnetic stimulation at a maximum value of 40%. Moreover, the microspheres were cytocompatible with fibroblasts in vitro with a cell viability percentage of more than 100% relative to a nontreated control after 24 hours of culture. Macrophage cell cultures showed no signs of increased inflammatory responses after in vitro incubation for 56 hours. Treatment of Staphylococcus aureus with the magnetic microspheres under an alternating (isolating) magnetic field increased bacterial inhibition further after 2 days and 5 days in a broth inhibition assay. The findings of the present study indicate that iron oxide NPs, maghemite and hematite, can be used as media for stimulation by an external magnetic energy to activate immediate drug release. PMID:26185446

  13. Cross-linking of IgG receptors inhibits membrane immunoglobulin-stimulated calcium influx in B lymphocytes.

    PubMed

    Choquet, D; Partiseti, M; Amigorena, S; Bonnerot, C; Fridman, W H; Korn, H

    1993-04-01

    By cross-linking membrane immunoglobulins (mIg), the antigenic stimulation of B lymphocytes induces an increase in intracellular free calcium levels ([Ca2+]i) because of a combination of release from intracellular stores and transmembrane influx. It has been suggested that both events are linked, as in a number of other cases of receptor-induced increase in [Ca2+]i. Conversely, in B lymphocytes, type II receptors for the Fc fragment of IgG (Fc gamma RII) inhibit mIg-mediated signaling. Thus, we have investigated at the level of single cells if these receptors could act on specific phases of mIg Ca2+ signaling. Lipopolysaccharide-activated murine B splenocytes and B lymphoma cells transfected with intact or truncated Fc gamma RII-cDNA were used to determine the domains of Fc gamma RII implicated in the inhibition of the Ca2+ signal. [Ca2+]i was measured in single fura-2-loaded cells by microfluorometry. The phases of release from intracellular stores and of transmembrane influx were discriminated by using manganese, which quenches fura-2, in the external medium as a tracer for bivalent cation entry. The role of membrane potential was studied by recording [Ca2+]i in cells voltage-clamped using the perforated patch-clamp method. Cross-linking of mIgM or mIgG with F(ab')2 fragments of anti-Ig antibodies induced a sustained rise in [Ca2+]i due to an extremely fast and transitory release of Ca2+ from intracellular stores and a long lasting transmembrane Ca2+ influx. The phase of influx, but not that of release, was inhibited by membrane depolarization. The increase in [Ca2+]i occurred after a delay inversely related to the dose of ligand. Co-cross-linking mIgs and Fc gamma RII with intact anti-Ig antibodies only triggered transitory release of Ca2+ from intracellular stores but no Ca2+ influx, even when the cell was voltage-clamped at negative membrane potentials. These transitory Ca2+ rises had similar amplitudes and delays to those induced by cross-linking mIgs alone

  14. Nitric oxide stimulates insulin gene transcription in pancreatic {beta}-cells

    SciTech Connect

    Campbell, S.C. . E-mail: s.c.campbell@ncl.ac.uk; Richardson, H.; Ferris, W.F.; Butler, C.S.; Macfarlane, W.M.

    2007-02-23

    Recent studies have identified a positive role for nitric oxide (NO) in the regulation of pancreatic {beta}-cell function. The aim of this study was to determine the effects of short-term exposure to NO on {beta}-cell gene expression and the activity of the transcription factor PDX-1. NO stimulated the activity of the insulin gene promoter in Min6 {beta}-cells and endogenous insulin mRNA levels in both Min6 and isolated islets of Langerhans. Addition of wortmannin prior to NO stimulation blocked the observed increases in insulin gene promoter activity. Although NO addition stimulated the phosphorylation of p38, inhibition by SB203580 did not block the effect of NO on the insulin gene promoter. NO addition also stimulated both the nuclear accumulation and the DNA binding activity of PDX-1. This study has shown that over 24 h, NO stimulates insulin gene expression, PI-3-kinase activity and the activity of the critical {beta}-cell transcription factor PDX-1.

  15. Inactivation of enzymes and oxidative modification of proteins by stimulated neutrophils.

    PubMed

    Oliver, C N

    1987-02-15

    Differentiated, stimulated HL-60 cells and freshly isolated, stimulated neutrophils inactivate glutamine synthetase (L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2) either inside or outside of Escherichia coli. Stimulated neutrophils also inactivate at least four endogenous enzymes which are inactivated by mixed-function oxidation (MFO) systems in vitro (L. Fucci, C.N. Oliver, M.J. Coon, and E.R. Stadtman (1983) Proc. Natl. Acad. Sci. USA 80, 1521-1525). The inactivation of glutamine synthetase by stimulated neutrophils exhibits characteristics similar to those previously described using both enzymic and nonenzymic MFO systems (R.L. Levine, C.N. Oliver, R.M. Fulks, and E.R. Stadtman (1981) Proc. Natl. Acad. Sci. USA 78, 2120-2124). Although the reaction occurs in the absence of Fe(III), it is stimulated by added Fe (III). Inactivation required molecular oxygen and is partially inhibited by Mn(II), catalase, superoxide dismutase, and metal chelators, ethylenediaminetetraacetic acid and o-phenanthroline. Both the kinetics and the extent of glutamine synthetase inactivation differ when neutrophils are stimulated with phorbol esters compared with formylated peptides. Glutamine synthetase inactivation catalyzed by MFO systems is accompanied by the formation of protein carbonyl derivatives which form stable hydrazones when treated with 2,4-dinitrophenylhydrazine. Multiple carbonyl derivatives are formed in the soluble protein fraction of stimulated neutrophils and these derivatives collectively exhibit an absorbance spectrum similar to that of glutamine synthetase inactivated by liver microsomal cytochrome P-450 MFO system (K. Nakamura, C.N. Oliver, and E.R. Stadtman (1985) Arch. Biochem. Biophys. 240, 319-329).

  16. Oxidative stress of vanadium-mediated oxygen free radical generation stimulated by aluminium on human erythrocytes.

    PubMed

    Abou-Seif, M A

    1998-03-01

    It has been suggested that aluminium stimulates vanadium-mediated superoxide radical generation. The oxidative stress of generated superoxide radicals on antioxidant enzyme activity, oxidation of NADH and NADPH, membrane lipid peroxidation and osmotic fragility in human red blood cells (RBC) was investigated. RBC were incubated with varying concentrations of vanadium and aluminium ions at 37 degrees C for 2 h. RBC incubated with vanadium ions showed significantly increased superoxide dismutase and catalase activities, and oxidized NADH and NADPH concentrations compared with control RBC preparations. Erythrocyte lipid peroxidation was assessed by measuring thiobarbituric acid reactivity. RBC incubated with elevated levels of vanadium showed significantly increased membrane lipid peroxidation when compared with control RBC; it increased further on addition of aluminium. A significant positive correlation was observed between the extent of vanadium induced membrane lipid peroxidation and the osmotic fragility of treated RBC. In the presence of vanadium, aluminium stimulates superoxide dismutase and catalase activities. NADH and NADPH oxidation and membrane lipid peroxidation, as well as increasing osmotic fragility of human erythrocytes. The stimulatory effect of aluminium was dependent on concentration. These results may have implications for the mechanism of toxicity of aluminium and vanadium in haemodialysis patients. PMID:9547897

  17. Alterations of rat liver mitochondrial oxidative phosphorylation and calcium uptake by benzo[a]pyrene.

    PubMed

    Salazar, Inés; Pavani, Mario; Aranda, Waldo; Maya, Juan Diego; Morello, Antonio; Ferreira, Jorge

    2004-07-01

    We report that oxidative phosphorylation and Ca2+ uptake processes are enhanced in liver mitochondria isolated from benzo[a]pyrene (B[a]P)-treated rats. The carcinogen did not affect either the respiratory control index or the Ca2+ control ratio. B[a]P treatment increased the oxidation rate of several substrates that donate electrons at the level of all three coupling sites, either the ADP- or Ca2+-stimulated rates or those observed after ADP or Ca2+ exhaustion. However, the efficiency of energy coupling was maintained because both ADP/O and Ca2+/site ratios remained unchanged. The electron flow through NADH-oxidase, NADH-duroquinone reductase, NADH-juglone reductase, NADH-cytochrome c reductase, succinate-cytochrome c reductase, and cytochrome c oxidase was enhanced by B[a]P; however, succinate dehydrogenase activity was not affected. All these effects depended on the time post B[a]P administration, with a greater increase close to 48 h after administration of the carcinogen. The contents of cytochromes b, c1, and a + a3 from liver mitochondria, especially those isolated 48 h after B[a]P, were also significantly increased, although cytochrome c levels was just lightly increased 24 h after B[a]P treatment. These results suggest that B[a]P treatment stimulates mitochondrial respiration by increasing the level of several components of the mitochondrial respiratory chain. This may reflect mitochondrial adaptation to the cellular energy requirements of cell division in the neoplastic transformation process.

  18. Influence of soil pH and application rate on the oxidation of calcium sulfite derived from flue gas desulfurization

    SciTech Connect

    Lee, Y.B.; Bigham, J.M.; Dick, W.A.; Jones, E.S.; Ramsier, C.

    2007-01-15

    Calcium sulfite hemihydrate (CaSO{sub 3} {center_dot} 0.5H{sub 2}O), a common byproduct of coal-fired utilities, is fairly insoluble and can decompose to release toxic SO{sub 2} under highly acidic soil conditions; however, it can also oxidize to form gypsum. The objective of this study was to examine the effects of application rate and soil pH on the oxidation of calcium sulfite under laboratory conditions. Oxidation rates measured by release of SO{sub 4}-S to solution decreased with increasing application rate. Leachate SO{sub 4}-S from soils amended with 1.0 to 3.0 g kg{sup -1} CaSO{sub 3} increased over a 21 to 28 d period before reaching a plateau. At 4 g kg{sup -1}, maximum SO{sub 4}-S release was delayed until Week 7. Oxidation and release of SO{sub 4}-S from soil amended with 3.0 g kg{sup -1} calcium sulfite increased markedly with decreasing soil pH. After only 3 d incubation, the concentrations of SO{sub 4}-S in aqueous leachates were 77, 122, 1709 220, and 229 mg L{sup -1} for initial soil pH values of 7.8, 6.5, 5.5, 5.1, and 4.0, respectively. At an initial soil pH value of 4.0, oxidation/dissolution did not increase much after 3 d. At higher pH values, oxidation was maximized after 21 d. These results suggest that autumn surface applications of calcium sulfite in no-till systems should permit ample time for oxidation/dissolution reactions to occur without introducing biocidal effects related to oxygen scavenging. Soil and annual crops can thus benefit from additions of soluble Ca and SO{sub 4} if calcium sulfite is applied in advance of spring planting.

  19. Laboratory Synthesized Calcium Oxide and Calcium Hydroxide Grains: A Candidate to Explain the 6.8 Micron Band

    NASA Technical Reports Server (NTRS)

    Kimura, Yuki; Nuth, Joseph A., III

    2005-01-01

    We will demonstrate that CaO and Ca(OH)2 are excellent candidates to explain the 6.8 microns feature, which is one of the most obscure features in young stellar objects. We discuss the condensation of CaO grains and the potential formation of a Ca(OH)2 surface layer. The infrared spectra of these grains are compared with the spectra of fifteen young stellar objects. We note that CaO-rich grains are seen in all meteoritic CAIs (calcium-aluminum-rich inclusions) and the 6.8 micron feature has only been observed in young stellar objects. Therefore, we consider CaO grains to be a plausible candidate to explain the 6.8 microns feature and hypothesize that they are produced in the hot interiors of young stellar environments.

  20. Formate oxidation-driven calcium carbonate precipitation by Methylocystis parvus OBBP.

    PubMed

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert; Boon, Nico

    2014-08-01

    Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such asammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2(-1) calcium carbonate precipitate yield was obtained when a culture of 10(9) cells ml(-1) and 5 g of calcium formate liter(-)1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry.

  1. Formate Oxidation-Driven Calcium Carbonate Precipitation by Methylocystis parvus OBBP

    PubMed Central

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert

    2014-01-01

    Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such as ammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2−1 calcium carbonate precipitate yield was obtained when a culture of 109 cells ml−1 and 5 g of calcium formate liter−1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry. PMID:24837386

  2. Ultrafiltered pig leukocyte extract (IMUNOR) decreases nitric oxide formation and hematopoiesis-stimulating cytokine production in lipopolysaccharide-stimulated RAW 264.7 macrophages.

    PubMed

    Hofer, Michal; Vacek, Antonín; Lojek, Antonín; Holá, Jirina; Streitová, Denisa

    2007-10-01

    A low-molecular-weight (<12 kDa) ultrafiltered pig leukocyte extract, IMUNOR, was tested in experiments in vitro on non-stimulated and lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages in order to assess modulation of nitric oxide (NO) production (measured indirectly as the concentration of nitrites), hematopoiesis-stimulating activity of the supernatant of the macrophage cells (ascertained by counting cell colonies growing from progenitor cells for granulocytes and macrophages (GM-CFC) in vitro), and the release of hematopoiesis-stimulating cytokines. No hematopoiesis-stimulating activity and cytokine or NO production were found in the supernatant of non-stimulated macrophages. It was found that IMUNOR does not influence this status. Supernatant of LPS-stimulated macrophages was characterized by hematopoiesis-stimulating activity, as well as by the presence of nitrites, interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF). A key role in the hematopoiesis-stimulating activity of the supernatant of LPS-stimulated macrophages could be ascribed to G-CSF since the formation of the colonies could be abrogated nearly completely by monoclonal antibodies against G-CSF. IMUNOR was found to suppress all the mentioned manifestations of the LPS-activated macrophages. When considering these results together with those from our previous in vivo study revealing stimulatory effects of IMUNOR on radiation-suppressed hematopoiesis, a hypothesis may be formulated which postulates a homeostatic role of IMUNOR, consisting in stimulation of impaired immune and hematopoietic systems but also in cutting back the production of proinflammatory mediators in cases of overstimulation which threats with undesirable consequences.

  3. Calcium- and Cobalt-doped Yttrium Chromites as an Interconnect Material for Solid Oxide Fuel Cells

    SciTech Connect

    Yoon, Kyung J.; Cramer, Carolyn N.; Thomsen, Edwin C.; Coyle, Christopher A.; Coffey, Greg W.; Marina, Olga A.

    2010-04-23

    The structural, thermal and electrical characteristics of calcium- and cobalt-doped yttrium chromites were studied for a potential use as the interconnect material in high temperature solid oxide fuel cells (SOFCs) as well as other high temperature electrochemical and thermoelectric devices. The Y0.8Ca0.2Cr1-xCoxO3±δ (x=0, 0.1, 0.2, 0.3) compositions had single phase orthorhombic perovskite structures in the wide range of oxygen pressures. Sintering behavior was remarkably enhanced upon cobalt doping and densities 95% and 97% of theoretical density were obtained after sintering at 1300oC in air, when x was 0.2 and 0.3, respectively. The electrical conductivity in both oxidizing and reducing atmospheres was significantly improved with cobalt content, and values of 49 and 10 S/cm at 850oC and 55 and 14 S/cm at 950oC in air and forming gas, respectively, were reported for x=0.2. The conductivity increase was attributed to the charge carrier density increase upon cobalt substitution for chromium confirmed with Seebeck measurements. The thermal expansion coefficient (TEC) was increased with cobalt content and closely matched to that of an 8 mol% yttria-stabilized zirconia (YSZ) electrolyte for 0.1 ≤ x ≤ 0.2. The chemical compatibility between Y0.8Ca0.2Cr1-xCoxO3±δ and YSZ was evaluated firing the two at 1400oC and no reaction products were found if x value was kept lower than 0.2.

  4. Calcium ions rescue human lung epithelial cells from the toxicity of zinc oxide nanoparticles.

    PubMed

    Hanagata, Nobutaka; Morita, Hiromi

    2015-01-01

    Contradictory results have been reported for in vitro evaluations of whether zinc oxide nanoparticles (ZnO NPs) are cytotoxic. Though there have been reports of ZnO NPs cytotoxicity due to Zn ions released from the nanoparticles, there have also been reports concluding that Zn ions are not cytotoxic. This inconsistency is mostly attributed to the types of cells used. In this research, we investigated the difference in the level of ZnO NPs cytotoxicity due to culturing conditions. The sensitivity of human lung epithelial cells to ZnO NPs cytotoxicity differed depending on the dispersing medium, physiological state of the cells resulting from their growth stage, and composition of the medium. Further, with regard to the toxicity of ZnO NPs, NPs internalized into cells had a greater cytotoxic effect than Zn ions released from ZnO NPs. Instead of inducing cell death, ZnO NPs internalized into cells slowed the rate of cell proliferation. Furthermore, the cytotoxicity of ZnO NPs depended greatly on the concentration of calcium ions (Ca2+) in the medium. When the concentration of Ca2+ was low, the cytotoxicity of ZnO NPs increased markedly. However, the toxicity of ZnO NPs was mitigated by the addition of CaCl2 to the medium. Global gene expression analysis revealed that Ca2+ -induced upregulation of cell cycle functions could be attributable to the mitigation of ZnO NP toxicity by Ca2+.

  5. Chemical Interactions of Barium-Calcium-Aluminosilicate Based Sealing Glasses with Oxidation Resistant Alloys

    SciTech Connect

    Yang, Z Gary ); Stevenson, Jeffry W. ); Meinhardt, Kerry D. )

    2003-04-04

    In most planar SOFC stack designs, the interconnect, which is typically made from an oxidation resistant alloy, potentially including austenitic chromia-forming, ferritic chromia-forming, and alumina-forming alloys, has to be hermitically sealed to its adjacent components, usually by a sealing glass. To maintain the structural stability and minimize the degradation of stack performance, the sealing glass must be chemically compatible with the alloy used for the interconnect. In this work, Nicrofer6025, AISI446 and a Fecralloy were selected as examples of austenitic chromia-forming, ferritic chromia-forming, and alumina-forming alloys, respectively. Their chemical compatibility with a barium-calcium-aluminosilicate (BCAS) based glass, specifically developed as a sealant in SOFC stacks, was evaluated. It was found that the BCAS sealing glass interacted chemically with both the chromia-forming alloys and the alumina-forming alloys. The extent and nature of the interactions and their final products depended on the matrix alloy compositions, the exposure conditions and/or proximity of the glass/alloy interface to the ambient air. These interactions and their mechanisms will be discussed with the assistance of thermodynamic modeling.

  6. Hydrogen Peroxide Signaling in Plant Development and Abiotic Responses: Crosstalk with Nitric Oxide and Calcium

    PubMed Central

    Niu, Lijuan; Liao, Weibiao

    2016-01-01

    Hydrogen peroxide (H2O2), as a reactive oxygen species, is widely generated in many biological systems. It has been considered as an important signaling molecule that mediates various physiological and biochemical processes in plants. Normal metabolism in plant cells results in H2O2 generation, from a variety of sources. Also, it is now clear that nitric oxide (NO) and calcium (Ca2+) function as signaling molecules in plants. Both H2O2 and NO are involved in plant development and abiotic responses. A wide range of evidences suggest that NO could be generated under similar stress conditions and with similar kinetics as H2O2. The interplay between H2O2 and NO has important functional implications to modulate transduction processes in plants. Moreover, close interaction also exists between H2O2 and Ca2+ in response to development and abiotic stresses in plants. Cellular responses to H2O2 and Ca2+ signaling systems are complex. There is quite a bit of interaction between H2O2 and Ca2+ signaling in responses to several stimuli. This review aims to introduce these evidences in our understanding of the crosstalk among H2O2, NO, and Ca2+ signaling which regulates plant growth and development, and other cellular and physiological responses to abiotic stresses. PMID:26973673

  7. Lattice-mismatch Strain Effects in Electron-Doped Calcium Manganese Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Hart, Cacie; Yong, Grace; Warecki, Zoey; Chaudhry, Adeel; Sharma, Prakash; Johnson, Anthony; Schaefer, David; Kolagani, Rajeswari

    2015-03-01

    Electron-doped Calcium Manganese Oxide (CaMnO3-δ) thin films are of interest for use as photocatalysts and fuel cell electrodes in renewable energy applications. Oxygen stoichiometry of the films is a key parameter for the functionality in these applications. Currently, we are investigating the properties of (CaMnO3-δ) films grown by pulsed laser deposition. The thin films are epitaxially grown on LaAlO3 and SrTiO3 substrates. Both of these substrates have larger in-plane lattice parameters than CaMnO3-δ, which leads to bi-axial tensile strain in the thin films. We have characterized the thickness dependence of structural, electrical, and morphological properties of these films using high resolution x-ray diffraction, temperature dependent electrical resistivity measurements, and atomic force microscopy. The thickness dependence is characteristically different from what has been preciously observed in thin films of hole-doped manganites. Our results suggest that coupling between tensile strain and oxygen deficiency affect the electrical and structural properties of the material. NSF Grant ECCS1128586.

  8. Interactive role of nitric oxide and calcium chloride in enhancing tolerance to salt stress.

    PubMed

    Khan, M Nasir; Siddiqui, Manzer H; Mohammad, Firoz; Naeem, M

    2012-12-01

    Nitric oxide (NO), a small diffusible, ubiquitous bioactive molecule, acts as prooxidant as well as antioxidant, and also regulates remarkable spectrum of plant cellular mechanisms. The present work was undertaken to investigate the role of nitric oxide donor sodium nitroprusside (SNP) and/or calcium chloride (CaCl(2)) in the tolerance of excised mustard leaves to salt stress. After 24h, salt stressed leaves treated with SNP and/or CaCl(2), showed an improvement in the activities of carbonic anhydrase (CA) and nitrate reductase (NR), and leaf chlorophyll (Chl) content, leaf relative water content (LRWC) and leaf ion concentration as compared with the leaves treated with NaCl only. Salinity stress caused a significant increase in H(2)O(2) content and membrane damage which is witnessed by enhanced levels of thiobarbituric acid reactive substances (TBARS) and electrolyte leakage. By contrast, such increases were blocked by the application of 0.2mM SNP and 10mM CaCl(2) to salt stressed leaves. Application of SNP and/or CaCl(2) alleviated NaCl stress by enhancing the activities of antioxidative enzymes viz. superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) and by enhancing proline (Pro) and glycinebetaine (GB) accumulation with a concomitant decrease in H(2)O(2) content, TBARS and electrolyte leakage, which is manifested in the tolerance of plants to salinity stress. Moreover, application of SNP with CaCl(2) was more effective to reduce the detrimental effects of NaCl stress on excised mustard leaves. In addition to this, ameliorating effect of SNP was not effective in presence of NO scavenger cPTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide]. To put all these in a nut shell, the results advocate that SNP in association with CaCl(2) plays a role in enhancing the tolerance of plants to salt stress by improving antioxidative defence system, osmolyte accumulation and ionic

  9. Oxidant stress stimulates mucin secretion and PLC in airway epithelium via a nitric oxide-dependent mechanism.

    PubMed

    Wright, D T; Fischer, B M; Li, C; Rochelle, L G; Akley, N J; Adler, K B

    1996-11-01

    Reactive oxygen species (ROS) have been implicated in the pathogenesis of a wide variety of respiratory diseases. We investigated mechanisms of ROS-induced mucin secretion by guinea pig tracheal epithelial (GPTE) cells in primary culture, and ROS-induced activation of the second messenger-producing enzyme phospholipase C (PLC), in GPTE cells and in a virally transformed cell line (BEAS-2B) derived from human bronchial epithelium. Mucin secretion was measured by a monoclonal antibody-based enzyme-linked immunosorbent assay, and PLC activation was assessed by anion exchange chromatography. ROS generated enzymatically by xanthine oxidase (XO, 500 microM) in the presence of purine (500 microM) enhanced release of mucin by GPTE cells and activated PLC in GPTE and BEAS cells. Hypersecretion of mucin and activation of PLC in response to purine + XO appeared to occur via an intracellular pathway(s) dependent on endogenously produced nitric oxide and possibly intracellularly generated oxidants. Both responses could be blocked or attenuated by preincubation of the cells with NG-monomethyl-L-arginine, an inhibitor of the enzyme nitric oxide synthase, or with dimethylthiourea, a compound that can react with a variety of intracellular oxidant species. Reactive nitrogen species generated chemically also stimulated secretion of mucin and activated PLC via a mechanism dependent (at least in part) on intracellular oxidant-mediated process(es). The results suggest that intracellularly generated radical species of nitrogen and oxygen may be important modulators of the response of airway epithelial cells to external oxidant stress.

  10. Glucose stimulates voltage- and calcium-dependent inositol trisphosphate production and intracellular calcium mobilization in insulin-secreting beta TC3 cells.

    PubMed Central

    Gromada, J; Frøkjaer-Jensen, J; Dissing, S

    1996-01-01

    The cellular processes leading to a rise in the intracellular free Ca2+ concentration ([Ca2+]i) after glucose stimulation and K+ depolarization were investigated in insulin-secreting beta TC-3 cells. Stimulation with 11.2mM glucose causes inositol 1,4,5-trisphosphate production and release of Ca2+ from intracellular stores. A strong correlation was observed between the changes in Ins(1,4,5)P3 concentration and the rise in [Ca2+]i, consistent with the former compound being responsible for release of Ca2+ from intracellular stores. The increase in Ins(1,4,5)P3 production was reduced by 68 +/- 4% when [Ca2+]i was kept low on glucose stimulation by loading cells with the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-NNN'N'-tetra-acetic acid (BAPTA). The Ins(1,4,5)P3 production was prevented in cells hyperpolarized with diazoxide, an opener of ATP-sensitive K+-channels, consistent with the membrane potential controlling the rate of Ins(1,4,5)P3 synthesis. Depolarizing K+ concentrations evoked changes in [Ca2+]i and Ins(1,4,5)P3 production in both the presence and the absence of extracellular Ca2+, and from the relation between the extracellular K+ concentration and membrane potential we found a half-maximal Ins(1,4,5)P3 production by a 28mV depolarization from a resting potential of -56mV and by a rise in [Ca2+]i of 390nM. We conclude that stimulation-induced changes in membrane potential and [Ca2+]i are important in controlling Ins(1,4,5)P3 production in beta TC-3 cells and that glucose-stimulated Ca2+ mobilization from intracellular stores is due to voltage-dependent Ins(1,45)P3 production and depends on the concurrent increase in [Ca2+]i. PMID:8660305

  11. A novel strontium(II)-modified calcium phosphate bone cement stimulates human-bone-marrow-derived mesenchymal stem cell proliferation and osteogenic differentiation in vitro.

    PubMed

    Schumacher, M; Lode, A; Helth, A; Gelinsky, M

    2013-12-01

    In the present study, the in vitro effects of novel strontium-modified calcium phosphate bone cements (SrCPCs), prepared using two different approaches on human-bone-marrow-derived mesenchymal stem cells (hMSCs), were evaluated. Strontium ions, known to stimulate bone formation and therefore already used in systemic osteoporosis therapy, were incorporated into a hydroxyapatite-forming calcium phosphate bone cement via two simple approaches: incorporation of strontium carbonate crystals and substitution of Ca(2+) by Sr(2+) ions during cement setting. All modified cements released 0.03-0.07 mM Sr(2+) under in vitro conditions, concentrations that were shown not to impair the proliferation or osteogenic differentiation of hMSCs. Furthermore, strontium modification led to a reduced medium acidification and Ca(2+) depletion in comparison to the standard calcium phosphate cement. In indirect and direct cell culture experiments with the novel SrCPCs significantly enhanced cell proliferation and differentiation were observed. In conclusion, the SrCPCs described here could be beneficial for the local treatment of defects, especially in the osteoporotic bone.

  12. A novel strontium(II)-modified calcium phosphate bone cement stimulates human-bone-marrow-derived mesenchymal stem cell proliferation and osteogenic differentiation in vitro.

    PubMed

    Schumacher, M; Lode, A; Helth, A; Gelinsky, M

    2013-12-01

    In the present study, the in vitro effects of novel strontium-modified calcium phosphate bone cements (SrCPCs), prepared using two different approaches on human-bone-marrow-derived mesenchymal stem cells (hMSCs), were evaluated. Strontium ions, known to stimulate bone formation and therefore already used in systemic osteoporosis therapy, were incorporated into a hydroxyapatite-forming calcium phosphate bone cement via two simple approaches: incorporation of strontium carbonate crystals and substitution of Ca(2+) by Sr(2+) ions during cement setting. All modified cements released 0.03-0.07 mM Sr(2+) under in vitro conditions, concentrations that were shown not to impair the proliferation or osteogenic differentiation of hMSCs. Furthermore, strontium modification led to a reduced medium acidification and Ca(2+) depletion in comparison to the standard calcium phosphate cement. In indirect and direct cell culture experiments with the novel SrCPCs significantly enhanced cell proliferation and differentiation were observed. In conclusion, the SrCPCs described here could be beneficial for the local treatment of defects, especially in the osteoporotic bone. PMID:23917042

  13. The role of calcium ions in the photocatalytic oxidation of humic acid at neutral pH.

    PubMed

    Mariquit, Eden G; Salim, Chris; Hinode, Hirofumi

    2008-10-01

    Humic acids (HAs) are natural organic matter derived from the decomposition of plant, algal, and microbial materials. They belong to the group of the most predominant type of natural organic matter present in ground and surface waters. HAs affect the mobility and bioavailability of aquatic contaminants. However, if they are left unremoved from the water before water treatment processes, they can form carcinogenic disinfection by-products, such as trihalomethanes, haloacetic acids, and other halogenated disinfection by-products, that can pose a threat to human beings. An advanced oxidation process using UV light and a commercially available titanium dioxide was used to oxidize HA at a pH that is similar to that of natural water. The effect of adding calcium ions to the adsorption and the photocatalytic oxidation of HAs was studied. The effect of varying the TiO(2) load was also investigated. The experiment was done using a photochemical batch reactor equipped with a mercury lamp emitting light with wavelengths of 310-580 nm. The absorbances by the samples were determined at wavelengths of 254 nm and 436 nm, which represent the aromatic-compound content of and the color of the solution, respectively. Results indicated calcium ions have an effect on both the adsorption and the photocatalytic oxidation of HA at a pH within 8.0 +/- 0.5. Calcium ions facilitated adsorption of HA onto the surface of TiO(2) and resulted to faster photocatalytic oxidation. The data were plotted with respect to the normalized absorbances and irradiation time. PMID:18991939

  14. Chronic ethanol intake modifies pyrrolidon carboxypeptidase activity in mouse frontal cortex synaptosomes under resting and K+ -stimulated conditions: role of calcium.

    PubMed

    Mayas, María Dolores; Ramírez-Expósito, María Jesús; García-López, María Jesús; Carrera, María Pilar; Martínez-Martos, José Manuel

    2008-07-01

    Pyrrolidon carboxypeptidase (Pcp) is an omega peptidase that removes pyroglutamyl N-terminal residues of peptides such as thyrotrophin-releasing hormone (TRH), which is one of the neuropeptides that has been localized into many areas of the brain and acts as an endogenous neuromodulator of several parameters related to ethanol (EtOH) consumption. In this study, we analysed the effects of chronic EtOH intake on Pcp activity on mouse frontal cortex synaptosomes and their corresponding supernatant under basal and K+ -stimulated conditions, in presence and absence of calcium (Ca2+) to know the regulation of Pcp on TRH. In basal conditions, chronic EtOH intake significantly decreased synaptosomes Pcp activity but only in absence of Ca2+. However, supernatant Pcp activity is also decreased in presence and absence of calcium. Under K+-stimulated conditions, chronic EtOH intake decreased synaptosomes Pcp activity but only in absence of Ca2+, whereas supernatant Pcp activity was significantly decreased only in presence of Ca2+. The general inhibitory effect of chronic EtOH intake on Pcp activity suggests an inhibition of TRH metabolism and an enhancement of TRH neurotransmitter/neuromodulator functions, which could be related to putative processes of tolerance to EtOH in which TRH has been involved. Our data may also indicate that active peptides and their degrading peptidases are released together to the synaptic cleft to regulate the neurotransmitter/neuromodulator functions of these peptides, through a Ca2+ -dependent mechanism.

  15. Screen-printed calcium-birnessite electrodes for water oxidation at neutral pH and an "electrochemical harriman series".

    PubMed

    Lee, Seung Y; González-Flores, Diego; Ohms, Jonas; Trost, Tim; Dau, Holger; Zaharieva, Ivelina; Kurz, Philipp

    2014-12-01

    A mild screen-printing method was developed to coat conductive oxide surfaces (here: fluorine-doped tin oxide) with micrometer-thick layers of presynthesized calcium manganese oxide (Ca-birnessite) particles. After optimization steps concerning the printing process and layer thickness, electrodes were obtained that could be used as corrosion-stable water-oxidizing anodes at pH 7 to yield current densities of 1 mA cm(-2) at an overpotential of less than 500 mV. Analyses of the electrode coatings of optimal thickness (≈10 μm) indicated that composition, oxide phase, and morphology of the synthetic Ca-birnessite particles were hardly affected by the screen-printing procedure. However, a more detailed analysis by X-ray absorption spectroscopy revealed small modifications of both the Mn redox state and the structure at the atomic level, which could affect functional properties such as proton conductivity. Furthermore, the versatile new screen-printing method was used for a comparative study of various transition-metal oxides concerning electrochemical water oxidation under "artificial leaf conditions" (neutral pH, fairly low overpotential and current density), for which a general activity ranking of RuO2 >Co3 O4 ≈(Ca)MnOx ≈NiO was observed. Within the group of screened manganese oxides, Ca-birnessite performed better than "Mn-only materials" such as Mn2 O3 and MnO2 .

  16. Screen-printed calcium-birnessite electrodes for water oxidation at neutral pH and an "electrochemical harriman series".

    PubMed

    Lee, Seung Y; González-Flores, Diego; Ohms, Jonas; Trost, Tim; Dau, Holger; Zaharieva, Ivelina; Kurz, Philipp

    2014-12-01

    A mild screen-printing method was developed to coat conductive oxide surfaces (here: fluorine-doped tin oxide) with micrometer-thick layers of presynthesized calcium manganese oxide (Ca-birnessite) particles. After optimization steps concerning the printing process and layer thickness, electrodes were obtained that could be used as corrosion-stable water-oxidizing anodes at pH 7 to yield current densities of 1 mA cm(-2) at an overpotential of less than 500 mV. Analyses of the electrode coatings of optimal thickness (≈10 μm) indicated that composition, oxide phase, and morphology of the synthetic Ca-birnessite particles were hardly affected by the screen-printing procedure. However, a more detailed analysis by X-ray absorption spectroscopy revealed small modifications of both the Mn redox state and the structure at the atomic level, which could affect functional properties such as proton conductivity. Furthermore, the versatile new screen-printing method was used for a comparative study of various transition-metal oxides concerning electrochemical water oxidation under "artificial leaf conditions" (neutral pH, fairly low overpotential and current density), for which a general activity ranking of RuO2 >Co3 O4 ≈(Ca)MnOx ≈NiO was observed. Within the group of screened manganese oxides, Ca-birnessite performed better than "Mn-only materials" such as Mn2 O3 and MnO2 . PMID:25346273

  17. Flexible, high-density microphotodiode array with integrated sputtered iridium oxide electrodes for retinal stimulation

    NASA Astrophysics Data System (ADS)

    Yang, Frank; Chang, Mao-Yen; Yang, Chung-Hua; Teng, Chih-Ciao; Fan, Long-Sheng

    2016-01-01

    To assess the charge-injection capacity of the sputtered iridium oxide film (SIROF) electrode on the retinal CMOS image sensor (CIS) chip, a polyimide-based flex device was designed and fabricated to package the retinal CIS chip. The polyimide-flex-based packaging process keeps the surface of photosensors clean, and the measured connection resistance meets the packaging requirement of the low-power retinal CIS chip. The in vitro experimental results show that the small SIROF electrodes can provide a biphasic charge injection per phase of 3.9 nC/ph to achieve the stimulation threshold at a polarization potential of -0.44 V.

  18. Pinoresinol-4,4'-di-O-beta-D-glucoside from Valeriana officinalis root stimulates calcium mobilization and chemotactic migration of mouse embryo fibroblasts.

    PubMed

    Do, Kee Hun; Choi, Young Whan; Kim, Eun Kyoung; Yun, Sung Ji; Kim, Min Sung; Lee, Sun Young; Ha, Jung Min; Kim, Jae Ho; Kim, Chi Dae; Son, Beung Gu; Kang, Jum Soon; Khan, Ikhlas A; Bae, Sun Sik

    2009-06-01

    Lignans are major constituents of plant extracts and have important pharmacological effects on mammalian cells. Here we showed that pinoresinol-4,4'-di-O-beta-D-glucoside (PDG) from Valeriana officinalis induced calcium mobilization and cell migration through the activation of lysophosphatidic acid (LPA) receptor subtypes. Stimulation of mouse embryo fibroblast (MEF) cells with 10 microM PDG resulted in strong stimulation of MEF cell migration and the EC(50) was about 2 microM. Pretreatment with pertussis toxin (PTX), an inhibitor of G(i) protein, completely blocked PDG-induced cell migration demonstrating that PDG evokes MEF cell migration through the activation of the G(i)-coupled receptor. Furthermore, pretreatment of MEF cells with Ki16425 (10 microM), which is a selective antagonist for LPA(1) and LPA(3) receptors, completely blocked PDG-induced cell migration. Likewise, PDG strongly induced calcium mobilization, which was also blocked by Ki16425 in a dose-dependent manner. Prior occupation of the LPA receptor with LPA itself completely blocked PDG-induced calcium mobilization. Finally, PDG-induced MEF cell migration was attenuated by pretreatment with a phosphatidylinositol 3-kinase (PI3K) inhibitor such as LY294002. Cells lacking downstream mediator of PI3K such as Akt1 and Akt2 (DKO cells) showed loss of PDG-induced migration. Re-expression of Akt1 (but not Akt2) completely restored PDG-induced DKO cell migration. Given these results, we conclude that PDG is a strong inducer of cell migration. We suggest that the pharmacological action of PDG may occur through the activation of an LPA receptor whereby activation of PI3K/Akt signaling pathway mediates PDG-induced MEF cell migration.

  19. Effects of deuterium oxide and galvanic vestibular stimulation on visual cortical cell function

    SciTech Connect

    Reinis, S.; Landolt, J.P.; Weiss, D.S.; Money, K.E.

    1984-03-01

    The spontaneous and evoked unit activities of complex visual cortical cells were recorded from Brodmann's area 18 in immobilized, unanesthetized cats before, during, and after stimulation of the vestibular system. The vestibular system was stimulated by intravenous injection of deuterium oxide (D2O)--a noted nystagmogenic agent--or by direct galvanic stimulation of the labyrinth. Measures of the receptive-field areas, poststimulus time histograms, directional preferences, and the optimal speed of the light bar stimulating the cell were obtained before and after the application of D2O. Directional preferences were determined in a novel manner, using a method derived from a hierarchical clustering technique. Data were collected and analyzed from a) visual cortical cells in cats with intact labyrinths, b) visual cortical cells in cats following bilateral labrinthectomies, and c) nonvisual cortical cells in cats with intact labyrinths. The other cellular characteristics were also altered by the D2O. Galvanic stimulation of the labyrinth resembles, in its effects, the injection of D2O. In labyrinth-intact cats, the time course of area 18 spontaneous activity dramatically increased 30 min or more after D2O was administered. It peaked 2-3 h later and still had not returned to preinjection levels even 7 h after the D2O administration. In bilaterally labyrinthectomized cats, the spontaneous activity of the visual cells did not change following D2O administration. In nonvisual cells from labyrinth-intact cats, the spontaneous activity demonstrated a slight but significant decrease over time after D2O injection. In pilot studies, the cats were injected with D2O. Within 8-10 min afterward, signs of positional nystagmus commenced; and within 30 min, problems in maintaining balance were noted. This continued for 7-8 h before disappearing. In the labyrinthectomized animals, such effects were not observed.

  20. HAp granules encapsulated oxidized alginate-gelatin-biphasic calcium phosphate hydrogel for bone regeneration.

    PubMed

    Sarker, Avik; Amirian, Jhaleh; Min, Young Ki; Lee, Byong Taek

    2015-11-01

    Bone repair in the critical size defect zone using 3D hydrogel scaffold is still a challenge in tissue engineering field. A novel type of hydrogel scaffold combining ceramic and polymer materials, therefore, was fabricated to meet this challenge. In this study, oxidized alginate-gelatin-biphasic calcium phosphate (OxAlg-Gel-BCP) and spherical hydroxyapatite (HAp) granules encapsulated OxAlg-Gel-BCP hydrogel complex were fabricated using freeze-drying method. Detailed morphological and material characterizations of OxAlg-Gel-BCP hydrogel (OGB00), 25wt% and 35wt% granules encapsulated hydrogel (OGB25 and OGB35) were carried out for micro-structure, porosity, chemical constituents, and compressive stress analysis. Cell viability, cell attachment, proliferation and differentiation behavior of rat bone marrow-derived stem cell (BMSC) on OGB00, OGB25 and OGB35 scaffolds were confirmed by MTT assay, Live-Dead assay, and confocal imaging in vitro experiments. Finally, OGB00 and OGB25 hydrogel scaffolds were implanted in the critical size defect of rabbit femoral chondyle for 4 and 8 weeks. The micro-CT analysis and histological studies conducted by H&E and Masson's trichrome demonstrated that a significantly higher (***p<0.001) and earlier bone formation happened in case of 25% HAp granules encapsulated OxAlg-Gel-BCP hydrogel than in OxAlg-Gel-BCP complex alone. All results taken together, HAp granules encapsulated OxAlg-Gel-BCP system can be a promising 3D hydrogel scaffold for the healing of a critical bone defect.

  1. Optimization of transesterification of rubber seed oil using heterogeneous catalyst calcium oxide

    NASA Astrophysics Data System (ADS)

    Inggrid, Maria; Kristanto, Aldi; Santoso, Herry

    2015-12-01

    Biodiesel is an alternative fuel manufactured with the help of alkali hydroxide catalyst through transesterification reaction of vegetable oil. This study aims to examine methods and the most suitable conditions for transesterification reaction producing biodiesel from crude rubber seed oil by varying process parameters such as the molar ratio of alcohol, CaO amount as the alkaline catalyst, and reaction time. The rubber seed oil has a high level of free fatty acid content, which means the use of homogenous alkaline catalyst gives some technological problems such as soap formation which leaded in difficulty in the separation and purification of the product. Calcium oxide (CaO) is one of the most favorable heterogeneous base catalysts because it's reusable, noncorrosive, and low cost. Pre-treatment was performed by acid esterification with H2SO4 as the catalyst to decrease the content of free fatty acid in the rubber seed oil, in this pretreatment process the 12% FFA of crude oil could be reduced to below 3% FFA. The product after esterification process was then transesterified by alkaline transesterification by varying process parameters to convert triglyceride into biodiesel. The study found that maximum curvature for biodiesel yield occurred at 9:1 molar ratio of alcohol, 5%w catalyst loading, and 3 hours reaction time. Design expert software is used to determine the optimum point from experimental data. The result showed that the optimum yield of methyl ester from transesterification was 73.5 % by mass with 0.69 degree of desirability. The yielded methyl ester was tested for its density, viscosity, acid number, and solubility to meet SNI requirement standards.

  2. Diets Based on Sugar Cane Treated with Calcium Oxide for Lambs

    PubMed Central

    Carvalho, G. G. P.; Garcia, R.; Pires, A. J. V.; Silva, R. R.; Detmann, E.; Filho, A. Eustaquio; Ribeiro, L. S. O.; Carvalho, L. M.

    2013-01-01

    This experiment was conducted to evaluate the intake, nutrient apparent digestibility and the effect of total collection days (two and four days) on apparent digestibility estimates for lambs fed diets containing sugar cane treated with calcium oxide (CaO). Eight Santa Inês castrated male lambs with a 16.6±1.8 kg body weight were used. The lambs were distributed in two 4×4 Latin squares, with four experimental periods of 14 d each. The animals were kept in 1.2 m2 individual pens, and the intake and digestibility evaluations were performed during the last four days of each period. The diets were formulated to be isonitrogenous, containing 14% crude protein (CP), and presenting 70% sugar cane treated with 0, 0.75, 1.5 or 2.25% of CaO (as-fed basis), corrected with 1% urea, and 30% concentrate. The sugar cane with added CaO was chopped, treated, and offered to the animals after 24 h of storage. The sugar cane with CaO increased the DM, OM, CP, NDF, NDFap, TC, NFCap and TDN intake (kg/d), when compared to natural sugar cane, and produced the same intake expressed as a percentage of body weight (% BW). The NFCap digestibility of the CaO-treated sugar cane was inferior to the NFCap digestibility in natural sugar cane. There was a linear increase in the DM intake with the CaO-added sugar cane, but the DM and NDF digestibility and the TDN content decreased linearly. The chemical treatment of sugar cane with CaO increases the intake but does not improve the nutrient digestibility. Two days of total fecal collection were found to be sufficient to estimate the total apparent digestibility in lambs. PMID:25049779

  3. The relative contribution of calcium, zinc and oxidation-based cross-links to the stiffness of Arion subfuscus glue.

    PubMed

    Braun, M; Menges, M; Opoku, F; Smith, A M

    2013-04-15

    Metal ions are present in many different biological materials, and are capable of forming strong cross-links in aqueous environments. The relative contribution of different metal-based cross-links was measured in the defensive glue produced by the terrestrial slug Arion subfuscus. This glue contains calcium, magnesium, zinc, manganese, iron and copper. These metals are essential to the integrity of the glue and to gel stiffening. Removal of all metals caused at least a 15-fold decrease in the storage modulus of the glue. Selectively disrupting cross-links involving hard Lewis acids such as calcium reduced the stiffness of the glue, while disrupting cross-links involving borderline Lewis acids such as zinc did not. Calcium is the most common cation bound to the glue (40 mmol l(-1)), and its charge is balanced primarily by sulphate at 82-84 mmol l(-1). Thus these ions probably play a primary role in bringing polymers together directly. Imine bonds formed as a result of protein oxidation also contribute substantially to the stiffness of the glue. Disrupting these bonds with hydroxylamine caused a 33% decrease in storage modulus of the glue, while stabilizing them by reduction with sodium borohydride increased the storage modulus by 40%. Thus a combination of metal-based bonds operates in this glue. Most likely, cross-links directly involving calcium play a primary role in bringing together and stabilizing the polymer network, followed by imine bond formation and possible iron coordination.

  4. A specific sequence of stimulation is required to induce synthesis of the antimicrobial molecule nitric oxide by mouse macrophages.

    PubMed Central

    Lorsbach, R B; Russell, S W

    1992-01-01

    Nitric oxide production by macrophages required either simultaneous or sequential exposure to gamma interferon and lipopolysaccharide; exposure to lipopolysaccharide followed by exposure to gamma interferon gave little response. The apparently evanescent nature of the lipopolysaccharide signal, necessitating persistent stimulation, could be essential to down-regulating nitric oxide production after bacteria are cleared in vivo. PMID:1563802

  5. Metallic oxide nanoparticles stimulate blood coagulation independent of their surface charge.

    PubMed

    Steuer, Heiko; Krastev, Rumen; Lembert, Nicolas

    2014-07-01

    Positively charged metallic oxides prevent blood coagulation whereas negatively charged metallic oxides are thrombogenic. This study was performed to examine whether this effect extends to metallic oxide nanoparticles. Oscillation shear rheometry was used to study the effect of zinc oxide and silicon dioxide nanoparticles on thrombus formation in human whole blood. Our data show that oscillation shear rheometry is a sensitive and robust technique to analyze thrombogenicity induced by nanoparticles. Blood without previous contact with nanoparticles had a clotting time (CT) of 16.7 ± 1.0 min reaching a maximal clot strength (CS) of 16 ± 14 Pa (G') after 30 min. ZnO nanoparticles (diameter 70 nm, +37 mV zeta-potential) at a concentration of 1 mg/mL prolonged CT to 20.8 ± 3.6 min and provoked a weak clot (CS 1.5 ± 1.0 Pa). However, at a lower concentration of 100 µg/mL the ZnO particles dramatically reduced CT to 6.0 ± 0.5 min and increased CS to 171 ± 63 Pa. This procoagulant effect decreased at lower concentrations reaching the detection limit at 10 ng/mL. SiO2 nanoparticles (diameter 232 nm, -28 mV zeta-potential) at high concentrations (1 mg/mL) reduced CT (2.1 ± 0.2 min) and stimulated CS (249 ± 59 Pa). Similar to ZnO particles, this procoagulant effect reached a detection limit at 10 ng/mL. Nanoparticles in high concentrations reproduce the surface charge effects on blood coagulation previously observed with large particles or solid metal oxides. However, nanoparticles with different surface charges equally well stimulate coagulation at lower concentrations. This stimulation may be an effect which is not directly related to the surface charge.

  6. Auger electron spectroscopy analysis of the first stages of thermally stimulated oxidation of GaAs(100)

    NASA Astrophysics Data System (ADS)

    Passeggi, M. C. G.; Vaquila, I.; Ferrón, J.

    1998-05-01

    The first stages (exposures <10 4 L) of thermally stimulated oxidation of GaAs(100) have been studied using Auger electron spectroscopy and principal component analysis. We compare the GaAs oxidation processes taking place at high (700 K) and room temperatures, and during simultaneous electron bombardment and oxygen exposure. We found that while at room temperature, GaAs oxidizes via a one-phase process involving the simultaneous oxidation of Ga and As, the high temperature process is characterized by the presence of two different GaAs oxide phases. The first phase involves the simultaneous oxidation of Ga and As while in the second, only Ga oxides are formed. On the other hand, under simultaneous oxygen exposure and electron irradiation, two different oxide phases appear, both of them exhibiting the same features of the room temperature process, i.e., the simultaneous oxidation of Ga and As.

  7. High-performance calcium-doped zinc oxide thin-film transistors fabricated on glass at low temperature

    NASA Astrophysics Data System (ADS)

    Yu, Wen; Han, Dedong; Cui, Guodong; Cong, Yingying; Dong, Junchen; Zhang, Xiaomi; Zhang, Xing; Wang, Yi; Zhang, Shengdong

    2016-04-01

    High-performance calcium-doped zinc oxide thin-film transistors (Ca-ZnO TFTs) have been successfully fabricated on transparent glass at low temperature by RF magnetron sputtering. To study the effects of calcium doping on zinc oxide thin-film transistors, the characteristics of Ca-ZnO TFTs and ZnO TFTs are compared and analyzed in detail from different perspectives, including electrical performance, surface morphology, and crystal structure of the material. The results suggest that the incorporation of calcium element can decrease the root-mean-square roughness of the material, suppress growth of a columnar structure, and improve device performance. The TFTs with Ca-ZnO active layer exhibit excellent electrical properties with the saturation mobility (μsat) of 147.1 cm2 V-1 s-1, threshold voltage (V t) of 2.91 V, subthreshold slope (SS) of 0.271 V/dec, and I on/I off ratio of 2.34 × 108. In addition, we also study the uniformity of the devices. The experimental results show that the Ca-ZnO TFTs possess good uniformity, which is important for large-area application.

  8. Homer1a attenuates glutamate-induced oxidative injury in HT-22 cells through regulation of store-operated calcium entry

    PubMed Central

    Rao, Wei; Peng, Cheng; Zhang, Lei; Su, Ning; Wang, Kai; Hui, Hao; Dai, Shu-hui; Yang, Yue-fan; Luo, Peng; Fei, Zhou

    2016-01-01

    Calcium disequilibrium is extensively involved in oxidative stress-induced neuronal injury. Although Homer1a is known to regulate several neuronal calcium pathways, its effects on, or its exact relationship with, oxidative stress-induced neuronal injury has not yet been fully elucidated. We found that Homer1a protected HT-22 cells from glutamate-induced oxidative stress injury by inhibiting final-phase intracellular calcium overload and mitochondrial oxidative stress. In these cells, stromal interactive molecule 1 (STIM1) puncta, but not the protein level, was significantly increased after glutamate treatment. Store-operated calcium entry (SOCE) inhibitors and cells in which a key component of SOCE (STIM1) was knocked out were used as glutamate-induced oxidative stress injury models. Both models demonstrated significant improvement of HT-22 cell survival after glutamate treatment. Additionally, increased Homer1a protein levels significantly inhibited SOCE and decreased the association of STIM1-Orai1 triggered by glutamate. These results suggest that up-regulation of Homer1a can protect HT-22 cells from glutamate-induced oxidative injury by disrupting the STIM1-Oria1 association, and then by inhibiting the SOCE-mediated final-phrase calcium overload. Thus, regulation of Homer1a, either alone or in conjunction with SOCE inhibition, may serve as key therapeutic interventional targets for neurological diseases in which oxidative stress is involved in the etiology or progression of the disease. PMID:27681296

  9. Puerarin activates endothelial nitric oxide synthase through estrogen receptor-dependent PI3-kinase and calcium-dependent AMP-activated protein kinase

    SciTech Connect

    Hwang, Yong Pil; Kim, Hyung Gyun; Hien, Tran Thi; Jeong, Myung Ho; Jeong, Tae Cheon; Jeong, Hye Gwang

    2011-11-15

    The cardioprotective properties of puerarin, a natural product, have been attributed to the endothelial nitric oxide synthase (eNOS)-mediated production of nitric oxide (NO) in EA.hy926 endothelial cells. However, the mechanism by which puerarin activates eNOS remains unclear. In this study, we sought to identify the intracellular pathways underlying eNOS activation by puerarin. Puerarin induced the activating phosphorylation of eNOS on Ser1177 and the production of NO in EA.hy926 cells. Puerarin-induced eNOS phosphorylation required estrogen receptor (ER)-mediated phosphatidylinositol 3-kinase (PI3K)/Akt signaling and was reversed by AMP-activated protein kinase (AMPK) and calcium/calmodulin-dependent kinase II (CaMKII) inhibition. Importantly, puerarin inhibited the adhesion of tumor necrosis factor (TNF)-{alpha}-stimulated monocytes to endothelial cells and suppressed the TNF-{alpha} induced expression of intercellular cell adhesion molecule-1. Puerarin also inhibited the TNF-{alpha}-induced nuclear factor-{kappa}B activation, which was attenuated by pretreatment with N{sup G}-nitro-L-arginine methyl ester, a NOS inhibitor. These results indicate that puerarin stimulates eNOS phosphorylation and NO production via activation of an estrogen receptor-mediated PI3K/Akt- and CaMKII/AMPK-dependent pathway. Puerarin may be useful for the treatment or prevention of endothelial dysfunction associated with diabetes and cardiovascular disease. -- Highlights: Black-Right-Pointing-Pointer Puerarin induced the phosphorylation of eNOS and the production of NO. Black-Right-Pointing-Pointer Puerarin activated eNOS through ER-dependent PI3-kinase and Ca{sup 2+}-dependent AMPK. Black-Right-Pointing-Pointer Puerarin-induced NO was involved in the inhibition of NF-kB activation. Black-Right-Pointing-Pointer Puerarin may help for prevention of vascular dysfunction and diabetes.

  10. Tyrosine administration decreases glutathione and stimulates lipid and protein oxidation in rat cerebral cortex.

    PubMed

    Sgaravatti, Angela M; Magnusson, Alessandra S; de Oliveira, Amanda S; Rosa, Andréa P; Mescka, Caroline Paula; Zanin, Fernanda R; Pederzolli, Carolina D; Wyse, Angela T S; Wannmacher, Clóvis M D; Wajner, Moacir; Dutra-Filho, Carlos Severo

    2009-09-01

    Tyrosine levels are abnormally elevated in tissues and physiological fluids of patients with inborn errors of tyrosine catabolism especially in tyrosinemia type II which is caused by deficiency of tyrosine aminotransferase (TAT) and provokes eyes, skin and central nervous system disturbances. We have recently reported that tyrosine promoted oxidative stress in vitro but the exact mechanisms of brain damage in these disorder are poorly known. In the present study, we investigated the in vivo effect of L-tyrosine (500 mg/Kg) on oxidative stress indices in cerebral cortex homogenates of 14-day-old Wistar rats. A single injection of L-tyrosine decreased glutathione (GSH) and thiol-disulfide redox state (SH/SS ratio) while thiobarbituric acid-reactive substances, protein carbonyl content and glucose-6-phosphate dehydrogenase activity were enhanced. In contrast, the treatment did not affect ascorbic acid content, and the activities of superoxide dismutase, catalase and glutathione peroxidase. These results indicate that acute administration of L-tyrosine may impair antioxidant defenses and stimulate oxidative damage to lipids and proteins in cerebral cortex of young rats in vivo. This suggests that oxidative stress may represent a pathophysiological mechanism in hypetyrosinemic patients.

  11. Neuropeptide Y stimulates retinal neural cell proliferation--involvement of nitric oxide.

    PubMed

    Alvaro, Ana Rita; Martins, João; Araújo, Inês M; Rosmaninho-Salgado, Joana; Ambrósio, António F; Cavadas, Cláudia

    2008-06-01

    Neuropeptide Y (NPY) is a 36 amino acid peptide widely present in the CNS, including the retina. Previous studies have demonstrated that NPY promotes cell proliferation of rat post-natal hippocampal and olfactory epithelium precursor cells. The aim of this work was to investigate the role of NPY on cell proliferation of rat retinal neural cells. For this purpose, primary retinal cell cultures expressing NPY, and NPY Y(1), Y(2), Y(4) and Y(5) receptors [Alvaro et al., (2007) Neurochem. Int., 50, 757] were used. NPY (10-1000 nM) stimulated cell proliferation through the activation of NPY Y(1), Y(2) and Y(5) receptors. NPY also increased the number of proliferating neuronal progenitor cells (BrdU(+)/nestin(+) cells). The intracellular mechanisms coupled to NPY receptors activation that mediate the increase in cell proliferation were also investigated. The stimulatory effect of NPY on cell proliferation was reduced by L-nitroarginine-methyl-esther (L-NAME; 500 microM), a nitric oxide synthase inhibitor, 1H-[1,2,4]oxadiazolo-[4, 3-a]quinoxalin-1-one (ODQ; 20 microM), a soluble guanylyl cyclase inhibitor or U0126 (1 microM), an inhibitor of the extracellular signal-regulated kinase 1/2 (ERK 1/2). In conclusion, NPY stimulates retinal neural cell proliferation, and this effect is mediated through nitric oxide-cyclic GMP and ERK 1/2 pathways.

  12. Carboxyethylpyrrole oxidative protein modifications stimulate neovascularization: Implications for age-related macular degeneration

    PubMed Central

    Ebrahem, Quteba; Renganathan, Kutralanathan; Sears, Jonathan; Vasanji, Amit; Gu, Xiaorong; Lu, Liang; Salomon, Robert G.; Crabb, John W.; Anand-Apte, Bela

    2006-01-01

    Choroidal neovascularization (CNV), the advanced stage of age-related macular degeneration (AMD), accounts for >80% of vision loss in AMD. Carboxyethylpyrrole (CEP) protein modifications, uniquely generated from oxidation of docosahexaenoate-containing lipids, are more abundant in Bruch’s membrane from AMD eyes. We tested the hypothesis that CEP protein adducts stimulate angiogenesis and possibly contribute to CNV in AMD. Human serum albumin (HSA) or acetyl-Gly-Lys-O-methyl ester (dipeptide) were chemically modified to yield CEP-modified HSA (CEP-HSA) or CEP-dipeptide. The in vivo angiogenic properties of CEP-HSA and CEP-dipeptide were demonstrated by using the chick chorioallantoic membrane and rat corneal micropocket assays. Low picomole amounts of CEP-HSA and CEP-dipeptide stimulated neovascularization. Monoclonal anti-CEP antibody neutralized limbal vessel growth stimulated by CEP-HSA, whereas anti-VEGF antibody was found to only partially neutralize vessel growth. Subretinal injections of CEP-modified mouse serum albumin exacerbated laser-induced CNV in mice. In vitro treatments of human retinal pigment epithelial cells with CEP-dipeptide or CEP-HSA did not induce increased VEGF secretion. Overall, these results suggest that CEP-induced angiogenesis utilizes VEGF-independent pathways and that anti-CEP therapeutic modalities might be of value in limiting CNV in AMD. PMID:16938854

  13. Chloroquine stimulates nitric oxide synthesis in murine, porcine, and human endothelial cells.

    PubMed Central

    Ghigo, D; Aldieri, E; Todde, R; Costamagna, C; Garbarino, G; Pescarmona, G; Bosia, A

    1998-01-01

    Nitric oxide (NO) is a free radical involved in the regulation of many cell functions and in the expression of several diseases. We have found that the antimalarial and antiinflammatory drug, chloroquine, is able to stimulate NO synthase (NOS) activity in murine, porcine, and human endothelial cells in vitro: the increase of enzyme activity is dependent on a de novo synthesis of some regulatory protein, as it is inhibited by cycloheximide but is not accompanied by an increased expression of inducible or constitutive NOS isoforms. Increased NO synthesis is, at least partly, responsible for chloroquine-induced inhibition of cell proliferation: indeed, NOS inhibitors revert the drug-evoked blockage of mitogenesis and ornithine decarboxylase activity in murine and porcine endothelial cells. The NOS-activating effect of chloroquine is dependent on its weak base properties, as it is exerted also by ammonium chloride, another lysosomotropic agent. Both compounds activate NOS by limiting the availability of iron: their stimulating effects on NO synthesis and inhibiting action on cell proliferation are reverted by iron supplementation with ferric nitrilotriacetate, and are mimicked by incubation with desferrioxamine. Our results suggest that NO synthesis can be stimulated in endothelial cells by chloroquine via an impairment of iron metabolism. PMID:9691096

  14. Localized Plasmon-Stimulated Nanochemistry of Graphene Oxide on a SERS Substrate.

    PubMed

    Ramanauskaite, Lina; Xu, Huizhong; Snitka, Valentinas

    2016-03-16

    In recent years, there has been remarkable progress in the reduction and functionalization of graphene oxide (GO) using nanoparticles and high-energy optical photons. Most of these reactions are carried out in solutions, whereas the local modification of GO on solid substrates still remains a challenge. In this work, we demonstrate the local reduction of GO and its further destruction, leading to the synthesis of polyaromatic hydrocarbons (PAHs) stimulated by localized surface plasmons (LSPs). The reduction of GO and the synthesis of PAHs have been carried out on a substrate designed for surface-enhanced Raman spectroscopy (SERS). We found that LSPs initiate the destruction of water molecules entrapped in the nanogaps between silver nanoparticles after the deposition of GO from the aqueous suspension. It was demonstrated that OH radicals, as a result of water decomposition, initiate the reduction of GO, leading to the synthesis of PAHs. The reactions have been observed in real time by using SERS. The measurement of current-voltage (I-V) characteristics through conductive atomic force microscopy (AFM), recorded in an LSP-stimulated area, have shown the increased electrical conductivity (more than ten times) compared with the conductivity of GO. The synthesis of new compounds in the LSP-stimulated area has been confirmed by the appearance of new peaks in the Raman spectra and nonlinear I-V characteristics typical for PAHs. We show that the used method allows the local modification of electrical properties of GO and controlled nanopattering of organic compounds on the surface.

  15. B1-b2 transition in calcium oxide from shock-wave and diamond-cell experiments.

    PubMed

    Jeanloz, R; Ahrens, T J; Mao, H K; Bell, P M

    1979-11-16

    Volume and structural data obtained by shock-wave and diamond-cell techniques demonstrate that calcium oxide transforms from the B1 (sodium chloride type) to the B2 (cesium chloride type) structure at 60 to 70 gigapascals (0.6 to 0.7 megabar) with a volume decrease of 11 percent. The agreement between the shockwave and diamond-cell results independently confirms the ruby-fluorescence pressure scale to about 65 gigapascals. The shock-wave data agree closely with ultrasonic measurements on the B1 phase and also agree satisfactorily with equations of state derived from ab initio calculations. The discovery of this B1-B2 transition is significant in that it allows considerable enrichment of calcium components in the earth's lower mantle, which is consistent with inhomogeneous accretion theories.

  16. Effect of co-existing copper and calcium on the removal of As(V) by reused aluminum oxides.

    PubMed

    Yang, J K; Park, Y J; Kim, K H; Lee, H Y; Min, K C; Lee, S M

    2013-01-01

    Among the various heavy metals, arsenic is frequently found in abandoned mine drainage and the environmental fate of arsenic in real aqueous solutions can be highly dependent on the presence of co-existing ions. In this study, removal of arsenate through adsorption on the reused aluminum oxide or through precipitation was investigated in a single and in a binary system as a function of pH and concentration. Different removal behaviors of arsenate were observed in the presence of different cations as well as a variation of the molar ratios of arsenate to cations. Co-operative effects on arsenate removal by precipitation in solution occurred with an increase of copper concentration, while a decrease of arsenate removal resulted in increasing calcium concentration. It was observed that the arsenate removal in the presence of calcium would be highly dependent on the molar ratios of both elements. PMID:23128638

  17. Effect of strontium ions on calcification of preosteoblasts cultured on porous calcium- and phosphate-containing titanium oxide layers formed by micro-arc oxidation.

    PubMed

    Sato, Mizuki; Chen, Peng; Tsutsumi, Yusuke; Shiota, Makoto; Hanawa, Takao; Kasugai, Shohei

    2016-01-01

    Strontium (Sr) ions were added to calcium- and phosphate-containing porous titanium oxide layers formed by micro-arc oxidation (MAO) of titanium (Ti) substrates to improve their osseointegration. An MC3T3-E1 preosteoblast was used to evaluate the effect of the incorporated Sr species on cell calcification. Similar surface microporous morphologies of the oxide layers were observed for all specimens produced by MAO, while the contents of the incorporated Sr ions increased with increasing Sr concentrations in MAO electrolytes. The calcium- and phosphate-containing porous layers promoted the cell alkaline phosphatase (ALP) activity, while cell calcification was promoted by the Sr addition. In particular, the ALP activity significantly increased after 10 days of culture, and larger areas of calcified deposits were observed for the specimens treated with MAO electrolytes containing 0.15 mol L(-1) of Sr species. The effect of Sr addition on the calcification of the MAO-treated Ti oxide layers was established in this study. PMID:27477229

  18. JTT-305, an orally active calcium-sensing receptor antagonist, stimulates transient parathyroid hormone release and bone formation in ovariectomized rats.

    PubMed

    Kimura, Shuichi; Nakagawa, Takashi; Matsuo, Yushi; Ishida, Yuji; Okamoto, Yoshihisa; Hayashi, Mikio

    2011-10-01

    Intermittent administration of parathyroid hormone (PTH) has a potent anabolic effect on bone in humans and animals. Calcium-sensing receptor (CaSR) antagonists stimulate endogenous PTH secretion through CaSR on the surface of parathyroid cells and thereby may be anabolic agents for osteoporosis. JTT-305 is a potent oral short-acting CaSR antagonist and transiently stimulates endogenous PTH secretion. The objective of the present study was to investigate the effects of JTT-305 on PTH secretion and bone in ovariectomized rats. Female rats, immediately after ovariectomy (OVX), were orally administered vehicle or JTT-305 (0.3, 1, or 3 mg/kg) for 12 weeks. The serum PTH concentrations were transiently elevated with increasing doses of JTT-305. In the proximal tibia, JTT-305 prevented OVX-induced decreases in both the cancellous and total bone mineral density (BMD) except for the 0.3mg/kg dose. At the 3mg/kg dose, JTT-305 increased the mineralizing surface and bone formation rate in histomorphometry. The efficacy of JTT-305 at the 3mg/kg dose on the BMD corresponded to that of exogenous rat PTH1-84 injection at doses between 3 and 10 μg/kg. In conclusion, JTT-305 stimulated endogenous transient PTH secretion and bone formation, and consequently prevented bone loss in OVX rats. These results suggest that JTT-305 is orally active and has the potential to be an anabolic agent for the treatment of osteoporosis.

  19. Stimulation of hERG1 channel activity promotes a calcium-dependent degradation of cyclin E2, but not cyclin E1, in breast cancer cells.

    PubMed

    Perez-Neut, Mathew; Shum, Andrew; Cuevas, Bruce D; Miller, Richard; Gentile, Saverio

    2015-01-30

    Cyclin E2 gene amplification, but not cyclin E1, has been recently defined as marker for poor prognosis in breast cancer, and appears to play a major role in proliferation and therapeutic resistance in several breast cancer cells. Our laboratory has previously reported that stimulation of the hERG1 potassium channel with selective activators led to down-regulation of cyclin E2 in breast cancer cells. In this work, we demonstrate that stimulation of hERG1 promotes an ubiquitin-proteasome-dependent degradation of cyclin E2 in multiple breast cancer cell lines representing Luminal A, HER2+ and Trastuzumab-resistant breast cancer cells. In addition we have also reveal that hERG1 stimulation induces an increase in intracellular calcium that is required for cyclin E2 degradation. This novel function for hERG1 activity was specific for cyclin E2, as cyclins A, B, D E1 were unaltered by the treatment. Our results reveal a novel mechanism by which hERG1 activation impacts the tumor marker cyclin E2 that is independent of cyclin E1, and suggest a potential therapeutic use for hERG1 channel activators.

  20. Stimulated stromal cells induce gamma-globin gene expression in erythroid cells via nitric oxide production

    PubMed Central

    Čokić, Vladan P.; Beleslin-Čokić, Bojana B.; Smith, Reginald D.; Economou, Antaeus P.; Wahl, Larry M.; Noguchi, Constance T.; Schechter, Alan N.

    2009-01-01

    Objective We have previously shown that nitric oxide (NO) is involved in the hydroxyurea-induced increase of gamma-globin gene expression in cultured human erythroid progenitor cells and that hydroxyurea increases NO production in endothelial cells via endothelial NO synthase (NOS). We have now expanded those studies to demonstrate that the stimulation of gamma-globin gene expression is also mediated by NOS induction in stromal cells within the bone marrow microenvironment. Materials and Methods Using NO analyzer, we measured NO production in endothelial and macrophage cell cultures. In co-culture studies of erythroid and stromal cells we measured globin gene expression during stimulation by NO inducers. Results Hydroxyurea (30–100 μM) induced NOS-dependent production of NO in human macrophages (up to 1.2 μM). Co-culture studies of human macrophages with erythroid progenitor cells also resulted in induction of gamma-globin mRNA expression (up to 3 fold) in the presence of hydroxyurea. NOS-dependent stimulation of NO by lipopolysaccharide (up to 0.6 μM) has been observed in human macrophages. We found that lipopolysaccharide and interferon-gamma together increased gamma-globin gene expression (up to 2 fold) in human macrophage/erythroid cell co-cultures. Co-culture of human bone marrow endothelial cells with erythroid progenitor cells also induced gamma-globin mRNA expression (2.4 fold) in the presence of hydroxyurea (40 μM). Conclusion These results demonstrate an arrangement by which NO and fetal hemoglobin inducers may stimulate globin genes in erythroid cells via the common paracrine effect of bone marrow stromal cells. PMID:19576950

  1. Nitric oxide and hypoxia stimulate erythropoietin receptor via MAPK kinase in endothelial cells.

    PubMed

    Cokic, Bojana B Beleslin; Cokic, Vladan P; Suresh, Sukanya; Wirt, Stacey; Noguchi, Constance Tom

    2014-03-01

    Erythropoietin receptor (EPOR) expression level determines the extent of erythropoietin (EPO) response. Previously we showed that EPOR expression in endothelial cells is increased at low oxygen tension and that EPO stimulation of endothelial cells during hypoxia can increase endothelial nitric oxide (NO) synthase (eNOS) expression and activation as well as NO production. We now observe that while EPO can stimulate NO production, NO in turn can regulate EPOR expression. Human umbilical vein endothelial cells (HUVEC) treated with 10-50 μM of NO donor diethylenetriamine NONOate (DETANO) for 24h showed significant induction of EPOR gene expression at 5% and 2% of oxygen. Also human bone marrow microvascular endothelial cell line (TrHBMEC) cultured at 21 and 2% oxygen with 50 μM DETANO demonstrated a time and oxygen dependent induction of EPOR mRNA expression after 24 and 48 h, particularly at low oxygen tension. EPOR protein was also induced by DETANO at 2% oxygen in TrHBMEC and HUVEC. The activation of signaling pathways by NO donor stimulation appeared to be distinct from EPO stimulation. In reporter gene assays, DETANO treatment of HeLa cells at 2% oxygen increased EPOR promoter activity indicated by a 48% increase in luciferase activity with a 2 kb EPOR promoter fragment and a 71% increase in activity with a minimal EPOR promoter fragment containing 0.2 kb 5'. We found that DETANO activated MAPK kinase in TrHBMEC both in normoxia and hypoxia, while MAPK kinase inhibition showed significant reduction of EPOR mRNA gene expression at low oxygen tension, suggesting MAPK involvement in NO mediated induction of EPOR. Furthermore, DETANO stimulated Akt anti-apoptotic activity after 30 min in normoxia, whereas it inhibited Akt phosphorylation in hypoxia. In contrast, EPO did not significantly increase MAPK activity while EPO stimulated Akt phosphorylation in TrHBMEC in normoxia and hypoxia. These observations provide a new effect of NO on EPOR expression to enhance EPO

  2. Effects of deuterium oxide and galvanic vestibular stimulation on visual cortical cell function.

    PubMed

    Reinis, S; Landolt, J P; Weiss, D S; Money, K E

    1984-03-01

    /he spontaneous and evoked unit activities of complex visual cortical cells were recorded from Brodmann's area 18 in immobilized, unanesthetized cats before, during, and after stimulation of the vestibular system. The vestibular system was stimulated by intravenous injection of deuterium oxide (D2O)--a noted nystagmogenic agent (14)--or by direct galvanic stimulation of the labyrinth. Measures of the receptive-field areas, poststimulus time histograms, directional preferences, and the optimal speed of the light bar stimulating the cell were obtained before and after the application of D2O. Directional preferences were determined in a novel manner, using a method derived from a hierarchical clustering technique (19). Data were collected and analyzed from a) visual cortical cells in cats with intact labyrinths, b) visual cortical cells in cats following bilateral labrinthectomies, and c) nonvisual cortical cells in cats with intact labyrinths. In cats with intact labyrinths, D2O changed the optimal length of the light bar that was able to stimulate the cortical cell as well as the path on which it evoked the response of the cell. Both values, which constitute the receptive field of the cell, changed approximately proportionately. This effect usually lasts for less than 4.5 h. The other cellular characteristics were also altered by the D2O. Galvanic stimulation of the labyrinth resembles, in its effects, the injection of D2O. In labyrinth-intact cats, the time course of area 18 spontaneous activity dramatically increased 30 min or more after D2O was administered. It peaked 2-3 h later and still had not returned to preinjection levels even 7 h after the D2O administration. In bilaterally labyrinthectomized cats, the spontaneous activity of the visual cells (and the other cellular characteristics studied) did not change following D2O administration. In nonvisual cells from labyrinth-intact cats, the spontaneous activity demonstrated a slight but significant decrease

  3. Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation.

    PubMed

    Chen, Zhan; Zhang, Weijun; Wang, Dongsheng; Ma, Teng; Bai, Runying; Yu, Dezhong

    2016-10-15

    The effects of combined calcium peroxide (CaO2) oxidation with chemical re-flocculation on dewatering performance and physicochemical properties of waste activated sludge was investigated in this study. The evolutions of extracellular polymeric substances (EPS) distribution, composition and morphological properties were analyzed to unravel the sludge conditioning mechanism. It was found that sludge filtration performance was enhanced by calcium peroxide oxidation with the optimal dosage of 20 mg/gTSS. However, this enhancement was not observed at lower dosages due to the absence of oxidation and the performance deteriorated at higher dosages because of the release of excess EPS, mainly as protein-like substances. The variation in soluble EPS (SEPS) component can be fitted well with pseudo-zero-order kinetic model under CaO2 treatment. At the same time, extractable EPS content (SEPS and loosely bound EPS (LB-EPS)) were dramatically increased, indicating sludge flocs were effectively broken and their structure became looser after CaO2 addition. The sludge floc structure was reconstructed and sludge dewaterability was significantly enhanced using chemical re-flocculation (polyaluminium chloride (PACl), ferric iron (FeCl3) and polyacrylamide (PAM)). The inorganic coagulants performed better in improving sludge filtration dewatering performance and reducing cake moisture content than organic polymer, since they could act as skeleton builders and decrease the sludge compressibility. PMID:27450355

  4. Calcium-activated potassium channels in cultured human endothelial cells are not directly modulated by nitric oxide.

    PubMed

    Haburcák, M; Wei, L; Viana, F; Prenen, J; Droogmans, G; Nilius, B

    1997-04-01

    Nitric oxide has been proposed to directly activated large conductance Ca(2+)-dependent K+ channels (BKCa) [Bolotina V.M., Najibi S., Palacino J.J., Pagano P.J., Cohen R.A. Nitric oxide directly activates calcium-dependent potassium channels in vascular smooth muscle. Nature 1994; 368: 850-853]. The nitric oxide (NO) donor S-nitrosocysteine (SNOC) was used to evaluate a possible direct modulation of BKCa by NO in EAhy926 (EA cells), a cultured human umbilical vein derived endothelial cell line, using the whole-cell, cell-attached and inside-out configuration of the patch-clamp technique, together with simultaneous amperometric measurement of NO and the concentration of free intracellular calcium [Ca2+]i. BKCa channels with a large conductance of approximately 190 pS, voltage-dependent activation and a reversal potential close to -80 mV have been identified in EA cells. Exposure of EA cells in the experimental chamber to 1 mM SNOC delivered approximately 5 microM NO, as recorded by an amperometric probe in situ. SNOC produced a modest increases in [Ca2+]i that was insufficient to activate BKCa channels. NO alone neither activated BKCa channels directly nor modulated preactivated BKCa channels in EA cells. These results do not support a direct modulatory effect of NO on large conductance BKCa channels in cultured endothelial cells. PMID:9160165

  5. Apnea stimulates the adaptive response to oxidative stress in elephant seal pups.

    PubMed

    Vázquez-Medina, José Pablo; Zenteno-Savín, Tania; Tift, Michael S; Forman, Henry Jay; Crocker, Daniel E; Ortiz, Rudy M

    2011-12-15

    Extended breath-hold (apnea) bouts are routine during diving and sleeping in seals. These apneas result in oxygen store depletion and blood flow redistribution towards obligatory oxygen-dependent tissues, exposing seals to critical levels of ischemia and hypoxemia. The subsequent reperfusion/reoxygenation has the potential to increase oxidant production and thus oxidative stress. The contributions of extended apnea to oxidative stress in adapted mammals are not well defined. To address the hypothesis that apnea in seals is not associated with increased oxidative damage, blood samples were collected from northern elephant seal pups (N=6) during eupnea, rest- and voluntary submersion-associated apneas, and post-apnea (recovery). Plasma 4-hydroxynonenal (HNE), 8-isoprostanes (8-isoPGF(2α)), nitrotyrosine (NT), protein carbonyls, xanthine and hypoxanthine (HX) levels, along with xanthine oxidase (XO) activity, were measured. Protein content of XO, superoxide dismutase 1 (Cu,ZnSOD), catalase and myoglobin (Mb), as well as the nuclear content of hypoxia inducible factor 1α (HIF-1α) and NF-E2-related factor 2 (Nrf2), were measured in muscle biopsies collected before and after the breath-hold trials. HNE, 8-iso PGF(2α), NT and protein carbonyl levels did not change among eupnea, apnea or recovery. XO activity and HX and xanthine concentrations were increased at the end of the apneas and during recovery. Muscle protein content of XO, CuZnSOD, catalase, Mb, HIF-1α and Nrf2 increased 25-70% after apnea. Results suggest that rather than inducing the damaging effects of hypoxemia and ischemia/reperfusion that have been reported in non-diving mammals, apnea in seals stimulates the oxidative stress and hypoxic hormetic responses, allowing these mammals to cope with the potentially detrimental effects associated with this condition.

  6. Protection against ventricular fibrillation via cholinergic receptor stimulation and the generation of nitric oxide

    PubMed Central

    Kalla, Manish; Chotalia, Minesh; Coughlan, Charles; Hao, Guoliang; Crabtree, Mark J.; Tomek, Jakub; Bub, Gil; Paterson, David J.

    2016-01-01

    Key points Animal studies suggest an anti‐fibrillatory action of the vagus nerve on the ventricle, although the exact mechanism is controversial.Using a Langendorff perfused rat heart, we show that the acetylcholine analogue carbamylcholine raises ventricular fibrillation threshold (VFT) and flattens the electrical restitution curve.The anti‐fibrillatory action of carbamylcholine was prevented by the nicotinic receptor antagonist mecamylamine, inhibitors of neuronal nitric oxide synthase (nNOS) and soluble guanylyl cyclase (sGC), and can be mimicked by the nitric oxide (NO) donor sodium nitroprusside.Carbamylcholine increased NO metabolite content in the coronary effluent and this was prevented by mecamylamine.The anti‐fibrillatory action of both carbamylcholine and sodium nitroprusside was ultimately dependent on muscarinic receptor stimulation as all effects were blocked by atropine.These data demonstrate a protective effect of carbamylcholine on VFT that depends upon both muscarinic and nicotinic receptor stimulation, where the generation of NO is likely to be via a neuronal nNOS–sGC dependent pathway. Abstract Implantable cardiac vagal nerve stimulators are a promising treatment for ventricular arrhythmia in patients with heart failure. Animal studies suggest the anti‐fibrillatory effect may be nitric oxide (NO) dependent, although the exact site of action is controversial. We investigated whether a stable analogue of acetylcholine could raise ventricular fibrillation threshold (VFT), and whether this was dependent on NO generation and/or muscarinic/nicotinic receptor stimulation. VFT was determined in Langendorff perfused rat hearts by burst pacing until sustained VF was induced. Carbamylcholine (CCh, 200 nmol l–1, n = 9) significantly (P < 0.05) reduced heart rate from 292 ± 8 to 224 ± 6 b.p.m. Independent of this heart rate change, CCh caused a significant increase in VFT (control 1.5 ± 0.3 mA, CCh 2.4 ± 0.4 mA, wash 1.1

  7. Evidence that cytosolic calcium increases are not sufficient to stimulate phospholipid scrambling in human T-lymphocytes.

    PubMed Central

    Wurth, Georjeana A; Zweifach, Adam

    2002-01-01

    Phospholipid scrambling, the disruption of normal plasma-membrane asymmetry, occurs during apoptotic and necrotic cell death and during the activation of platelets and neutrophils. It is currently believed that phospholipid scrambling is triggered simply by increases in bulk cytosolic [Ca(2+)]. We have presented evidence previously that the styryl dye FM1-43 is sensitive to phospholipid scrambling in Jurkat human leukaemic T-lymphocytes. Here we have used FM1-43, in combination with fura 2 and the Ca(2+)-elevating agents ionomycin and thapsigargin, in imaging experiments to test the idea that increases in bulk cytosolic [Ca(2+)] stimulate scrambling. Intracellular Ca(2+) increases of approximately 2 microM accompanied ionomycin-stimulated scrambling in approximately 50% of cells, and scrambling occurred in >99% of cells in which intracellular Ca(2+) rose to 4 microM. Chelating intracellular Ca(2+) with bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid or EGTA suppressed both ionomycin-stimulated intra cellular Ca(2+) increases and scrambling, demonstrating that intracellular Ca(2+) increases are necessary for ionomycin-stimulated scrambling. However, elevating intracellular Ca(2+) to 2-4 microM with thapsigargin, a drug that depletes intracellular Ca(2+) stores and triggers Ca(2+) entry via Ca(2+)-release-activated Ca(2+) channels, did not trigger scrambling, as assessed with either FM1-43 or FITC-labelled annexin V. These results suggest that increases in intracellular [Ca(2+)] are necessary but not sufficient to stimulate scrambling in lymphoyctes, and indicate that ionomycin has an additional effect that is required to stimulate scrambling. PMID:11879198

  8. Developmental axon stretch stimulates neuron growth while maintaining normal electrical activity, intracellular calcium flux, and somatic morphology

    PubMed Central

    Loverde, Joseph R.; Pfister, Bryan J.

    2015-01-01

    Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18% applied over 5 min. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25% strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury. PMID:26379492

  9. The active metabolite of prasugrel inhibits ADP-stimulated thrombo-inflammatory markers of platelet activation: Influence of other blood cells, calcium, and aspirin.

    PubMed

    Frelinger, Andrew L; Jakubowski, Joseph A; Li, Youfu; Barnard, Marc R; Fox, Marsha L; Linden, Matthew D; Sugidachi, Atsuhiro; Winters, Kenneth J; Furman, Mark I; Michelson, Alan D

    2007-07-01

    The novel thienopyridine prodrug prasugrel, a platelet P2Y(12) ADP receptor antagonist, requires in vivo metabolism for activity. Although pharmacological data have been collected on the effects of prasugrel on platelet aggregation, there are few data on the direct effects of the prasugrel's active metabolite, R-138727, on other aspects of platelet function. Here we examined the effects of R-138727 on thrombo-inflammatory markers of platelet activation, and the possible modulatory effects of other blood cells, calcium, and aspirin. Blood (PPACK or citrate anticoagulated) from healthy donors pre- and post-aspirin was incubated with R-138727 and the response to ADP assessed in whole blood or platelet-rich plasma (PRP) by aggregometry and flow cytometric analysis of leukocyte-platelet aggregates, platelet surface P-selectin, and GPIIb-IIIa activation. Low-micromolar concentrations of R-138727 resulted in a rapid and consistent inhibition of these ADP-stimulated thrombo-inflammatory markers. These rapid kinetics required physiological calcium levels, but were largely unaffected by aspirin. Lower IC(50) values in whole blood relative to PRP suggested that other blood cells affect ADP-induced platelet activation and hence the net inhibition by R-138727. R-138727 did not inhibit P2Y(12)-mediated ADP-induced shape change, even at concentrations that completely inhibited platelet aggregation, confirming the specificity of R-138727 for P2Y(12). In conclusion, R-138727, the active metabolite of prasugrel, results in rapid, potent, consistent, and selective inhibition of P2Y(12)-mediated up-regulation of thrombo-inflammatory markers of platelet activation. This inhibition is enhanced in the presence other blood cells and calcium, but not aspirin. PMID:17598013

  10. Coordinate High-Frequency Pattern of Stimulation and Calcium Levels Control the Induction of LTP in Striatal Cholinergic Interneurons

    ERIC Educational Resources Information Center

    Bonsi, Paola; De Persis, Cristiano; Calabresi, Paolo; Bernardi, Giorgio; Pisani, Antonio

    2004-01-01

    Current evidence appoints a central role to cholinergic interneurons in modulating striatal function. Recently, a long-term potentiation (LTP) of synaptic transmission has been reported to occur in these neurons. The relationship between the pattern of cortico/thalamostriatal fibers stimulation, the consequent changes in the intracellular calcium…

  11. Calcium-calmodulin-dependent kinase II (CaMKII) mediates insulin-stimulated proliferation and glucose uptake.

    PubMed

    Illario, Maddalena; Monaco, Sara; Cavallo, Anna Lina; Esposito, Iolanda; Formisano, Pietro; D'Andrea, Luca; Cipolletta, Ersilia; Trimarco, Bruno; Fenzi, Gianfranco; Rossi, Guido; Vitale, Mario

    2009-05-01

    Cellular growth and glucose uptake are regulated by multiple signals generated by the insulin receptor. The mechanisms of individual modulation of these signals remain somewhat elusive. We investigated the role of CaMKII in insulin signalling in a rat skeletal muscle cell line, demonstrating that CaMKII modulates the insulin action on DNA synthesis and the negative feedback that down regulates glucose uptake. Insulin stimulation generated partly independent signals leading to the rapid activation of Akt, Erk-1/2 and CaMKII. Akt activation was followed by Glut-4 translocation to the plasma membrane and increase of glucose uptake. Then, IRS-1 was phosphorylated at S612, the IRS-1/p85PI3K complex was disrupted, Akt was no more phosphorylated and both Glut-4 translocation and glucose uptake were reduced. Inhibition of CaMKII abrogated the insulin-induced Erk-1/2 activation, DNA synthesis and phosphorylation of IRS-1 at S612. Inhibition of CaMKII also abrogated the down-regulation of insulin-stimulated Akt phosphorylation, Glut-4 membrane translocation and glucose uptake. These results demonstrate that: 1 - CaMKII modulates the insulin-induced Erk-1/2 activation and cell proliferation; 2 - after the initial stimulation of the IRS-1/Akt pathway, CaMKII mediates the down-regulation of stimulated glucose uptake. This represents a novel mechanism in the selective control of insulin signals, and a possible site for pharmacological intervention.

  12. Lipoxin A4 Stimulates Calcium-Activated Chloride Currents and Increases Airway Surface Liquid Height in Normal and Cystic Fibrosis Airway Epithelia

    PubMed Central

    Al-Alawi, Mazen; Costello, Richard W.; McNally, Paul; Chiron, Raphaël; Harvey, Brian J.; Urbach, Valérie

    2012-01-01

    Cystic Fibrosis (CF) is a genetic disease characterised by a deficit in epithelial Cl− secretion which in the lung leads to airway dehydration and a reduced Airway Surface Liquid (ASL) height. The endogenous lipoxin LXA4 is a member of the newly identified eicosanoids playing a key role in ending the inflammatory process. Levels of LXA4 are reported to be decreased in the airways of patients with CF. We have previously shown that in normal human bronchial epithelial cells, LXA4 produced a rapid and transient increase in intracellular Ca2+. We have investigated, the effect of LXA4 on Cl− secretion and the functional consequences on ASL generation in bronchial epithelial cells obtained from CF and non-CF patient biopsies and in bronchial epithelial cell lines. We found that LXA4 stimulated a rapid intracellular Ca2+ increase in all of the different CF bronchial epithelial cells tested. In non-CF and CF bronchial epithelia, LXA4 stimulated whole-cell Cl− currents which were inhibited by NPPB (calcium-activated Cl− channel inhibitor), BAPTA-AM (chelator of intracellular Ca2+) but not by CFTRinh-172 (CFTR inhibitor). We found, using confocal imaging, that LXA4 increased the ASL height in non-CF and in CF airway bronchial epithelia. The LXA4 effect on ASL height was sensitive to bumetanide, an inhibitor of transepithelial Cl− secretion. The LXA4 stimulation of intracellular Ca2+, whole-cell Cl− currents, conductances and ASL height were inhibited by Boc-2, a specific antagonist of the ALX/FPR2 receptor. Our results provide, for the first time, evidence for a novel role of LXA4 in the stimulation of intracellular Ca2+ signalling leading to Ca2+-activated Cl− secretion and enhanced ASL height in non-CF and CF bronchial epithelia. PMID:22662206

  13. Orexin/hypocretin activates mTOR complex 1 (mTORC1) via an Erk/Akt-independent and calcium-stimulated lysosome v-ATPase pathway.

    PubMed

    Wang, Zhiqiang; Liu, Shimeng; Kakizaki, Miyo; Hirose, Yuuki; Ishikawa, Yukiko; Funato, Hiromasa; Yanagisawa, Masashi; Yu, Yonghao; Liu, Qinghua

    2014-11-14

    The lack of the neuropeptide orexin, also known as hypocretin, results in narcolepsy, a chronic sleep disorder characterized by frequent sleep/cataplexy attacks and rapid eye movement sleep abnormalities. However, the downstream pathways of orexin signaling are not clearly understood. Here, we show that orexin activates the mTOR pathway, a central regulator of cell growth and metabolism, in the mouse brain and multiple recombinant cell lines that express the G protein-coupled receptors (GPCRs), orexin 1 receptor (OX1R) or orexin 2 receptor (OX2R). This orexin/GPCR-stimulated mTOR activation is sensitive to rapamycin, an inhibitor of mTOR complex 1 (mTORC1) but is independent of two well known mTORC1 activators, Erk and Akt. Rather, our studies indicate that orexin activates mTORC1 via extracellular calcium influx and the lysosome pathway involving v-ATPase and Rag GTPases. Moreover, a cytoplasmic calcium transient is sufficient to mimic orexin/GPCR signaling to mTORC1 activation in a v-ATPase-dependent manner. Together, our studies suggest that the mTORC1 pathway functions downstream of orexin/GPCR signaling, which plays a crucial role in many physiological and metabolic processes.

  14. 65-kilodalton protein phosphorylated by interleukin 2 stimulation bears two putative actin-binding sites and two calcium-binding sites

    SciTech Connect

    Zu, Youli; Shigesada, Katsuya; Hanaoka, Masao; Namba, Yuziro ); Nishida, Eisuke ); Kubota, Ichiro ); Kohno, Michiaki )

    1990-09-11

    The authors have previously characterized a 65-kilodalton protein (p65) as an interleukin 2 stimulated phosphoprotein in human T cells and showed that three endopeptide sequences of p65 are present in the sequence of l-plastin. In this paper, they present the complete primary structure of p65 based on the cDNA isolated from a human T lymphocyte (KUT-2) cDNA library. Analysis of p65 sequences and the amino acid composition of cleaved p65 N-terminal peptide indicated that the deduced p65 amino acid sequence exactly coincides with that of l-plastin over the C-terminal 580 residues and has a 57-residue extension at the N-terminus to l-plastin. Computer-assisted structural analysis revealed that p65 is a multidomain molecule involving at least three intriguing functional domains: two putative calcium-binding sites along the N-terminal 80 amino acid residues; a putative calmodulin-binding site following the calcium-binding region; and two tandem repeats of putative actin-binding domains in its middle and C-terminal parts, each containing approximately 240 amino acid residues. These results suggest that p65 belongs to actin-binding proteins.

  15. The Effects of Vitamin D-K-Calcium Co-Supplementation on Endocrine, Inflammation, and Oxidative Stress Biomarkers in Vitamin D-Deficient Women with Polycystic Ovary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial.

    PubMed

    Razavi, M; Jamilian, M; Karamali, M; Bahmani, F; Aghadavod, E; Asemi, Z

    2016-07-01

    The current study was conducted to assess the effects of vitamin D-K-calcium co-supplementation on endocrine, inflammation, and oxidative stress biomarkers in vitamin D-deficient women with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was performed on 60 vitamin D-deficient women diagnosed with PCOS aged 18-40 years old. Participants were randomly allocated into 2 groups to intake either 200 IU vitamin D, 90 μg vitamin K plus, 500 mg calcium supplements (n=30), or placebo (n=30) twice a day for 8 weeks. Endocrine, inflammation, and oxidative stress biomarkers were quantified at the beginning and the end of the study. After 8 weeks of intervention, compared with the placebo, vitamin D-K-calcium co-supplementation resulted in a significant reduction in serum-free testosterone (- 2.1±1.6 vs.+0.1±1.0 pg/ml, p<0.001) and dehydroepiandrosterone sulfate (DHEAS) levels (- 0.8±1.0 vs.-0.1±0.5 μg/ml, p=0.006). In addition, a significant increase in plasma total antioxidant capacity (TAC) (+ 75.7±126.1 vs.-80.4±242.8 mmol/l, p=0.005) and a significant difference in plasma malondialdehyde (MDA) concentrations (+ 0.03±0.6 vs.+1.4±2.4 μmol/l, p=0.005) was observed following the supplementation with vitamin D-K-calcium compared with the placebo. A trend toward a greater decrease in luteinizing hormone was observed in vitamin D-K-calcium co-supplement group compared to placebo group (- 7.0 vs.-1.2 IU/l, p=0.09). We did not find any significant effect of vitamin D-K-calcium co-supplementation on prolactin, follicle-stimulating hormone, 17-OH progesterone, inflammatory markers, and glutathione levels. Overall, vitamin D-K-calcium co-supplementation for 8 weeks among vitamin D-deficient women with PCOS had beneficial effects on serum DHEAS, free testosterone, plasma TAC, and MDA levels.

  16. Angiotensin II stimulates superoxide production by nitric oxide synthase in thick ascending limbs.

    PubMed

    Gonzalez-Vicente, Agustin; Saikumar, Jagannath H; Massey, Katherine J; Hong, Nancy J; Dominici, Fernando P; Carretero, Oscar A; Garvin, Jeffrey L

    2016-02-01

    Angiotensin II (Ang II) causes nitric oxide synthase (NOS) to become a source of superoxide (O2 (-)) via a protein kinase C (PKC)-dependent process in endothelial cells. Ang II stimulates both NO and O2 (-) production in thick ascending limbs. We hypothesized that Ang II causes O2 (-) production by NOS in thick ascending limbs via a PKC-dependent mechanism. NO production was measured in isolated rat thick ascending limbs using DAF-FM, whereas O2 (-) was measured in thick ascending limb suspensions using the lucigenin assay. Consistent stimulation of NO was observed with 1 nmol/L Ang II (P < 0.001; n = 9). This concentration of Ang II-stimulated O2 (-) production by 50% (1.77 ± 0.26 vs. 2.62 ± 0.36 relative lights units (RLU)/s/μg protein; P < 0.04; n = 5). In the presence of the NOS inhibitor L-NAME, Ang II-stimulated O2 (-) decreased from 2.02 ± 0.29 to 1.10 ± 0.11 RLU/s/μg protein (P < 0.01; n = 8). L-arginine alone did not change Ang II-stimulated O2 (-) (2.34 ± 0.22 vs. 2.29 ± 0.29 RLU/s/μg protein; n = 5). In the presence of Ang II plus the PKC α/β1 inhibitor Gö 6976, L-NAME had no effect on O2 (-) production (0.78 ± 0.23 vs. 0.62 ± 0.11 RLU/s/μg protein; n = 7). In the presence of Ang II plus apocynin, a NADPH oxidase inhibitor, L-NAME did not change O2 (-) (0.59 ± 0.04 vs. 0.61 ± ×0.08 RLU/s/μg protein; n = 5). We conclude that: (1) Ang II causes NOS to produce O2 (-) in thick ascending limbs via a PKC- and NADPH oxidase-dependent process; and (2) the effect of Ang II is not due to limited substrate.

  17. The BRCA1 Tumor Suppressor Binds to Inositol 1,4,5-Trisphosphate Receptors to Stimulate Apoptotic Calcium Release*

    PubMed Central

    Hedgepeth, Serena C.; Garcia, M. Iveth; Wagner, Larry E.; Rodriguez, Ana M.; Chintapalli, Sree V.; Snyder, Russell R.; Hankins, Gary D. V.; Henderson, Beric R.; Brodie, Kirsty M.; Yule, David I.; van Rossum, Damian B.; Boehning, Darren

    2015-01-01

    The inositol 1,4,5-trisphosphate receptor (IP3R) is a ubiquitously expressed endoplasmic reticulum (ER)-resident calcium channel. Calcium release mediated by IP3Rs influences many signaling pathways, including those regulating apoptosis. IP3R activity is regulated by protein-protein interactions, including binding to proto-oncogenes and tumor suppressors to regulate cell death. Here we show that the IP3R binds to the tumor suppressor BRCA1. BRCA1 binding directly sensitizes the IP3R to its ligand, IP3. BRCA1 is recruited to the ER during apoptosis in an IP3R-dependent manner, and, in addition, a pool of BRCA1 protein is constitutively associated with the ER under non-apoptotic conditions. This is likely mediated by a novel lipid binding activity of the first BRCA1 C terminus domain of BRCA1. These findings provide a mechanistic explanation by which BRCA1 can act as a proapoptotic protein. PMID:25645916

  18. Resveratrol inhibits collagen-induced platelet stimulation through suppressing NADPH oxidase and oxidative inactivation of SH2 domain-containing protein tyrosine phosphatase-2.

    PubMed

    Jang, Ji Yong; Min, Ji Hyun; Wang, Su Bin; Chae, Yun Hee; Baek, Jin Young; Kim, Myunghee; Ryu, Jae-Sang; Chang, Tong-Shin

    2015-12-01

    Reactive oxygen species (ROS) produced upon collagen stimulation are implicated in propagating various platelet-activating pathways. Among ROS-producing enzymes, NADPH oxidase (NOX) is largely responsible for collagen receptor-dependent ROS production. Therefore, NOX has been proposed as a novel target for the development of antiplatelet agent. We here investigate whether resveratrol inhibits collagen-induced NOX activation and further examine the effects of resveratrol on ROS-dependent signaling pathways in collagen-stimulated platelets. Collagen-induced superoxide anion production in platelets was inhibited by resveratrol. Resveratrol suppressed collagen-induced phosphorylation of p47(phox), a major regulatory subunit of NOX. Correlated with the inhibitory effects on NOX, resveratrol protected SH2 domain-containing protein tyrosine phosphatase-2 (SHP-2) from ROS-mediated inactivation and subsequently attenuated the specific tyrosine phosphorylation of key components (spleen tyrosine kinase, Vav1, Bruton's tyrosine kinase, and phospholipase Cγ2) for collagen receptor signaling cascades. Resveratrol also inhibited downstream responses such as cytosolic calcium elevation, P-selectin surface exposure, and integrin-αIIbβ3 activation. Furthermore, resveratrol inhibited platelet aggregation and adhesion in response to collagen. The antiplatelet effects of resveratrol through the inhibition of NOX-derived ROS production and subsequent oxidative inactivation of SHP-2 suggest that resveratrol is a potential compound for prevention and treatment of thrombovascular diseases.

  19. Oxidative stress and altered steroidogenesis in the ovary by cholinergic stimulation of coeliac ganglion in the first proestrous in rats. Implication of nitric oxide.

    PubMed

    Delsouc, María B; Della Vedova, María C; Ramírez, Darío; Anzulovich, Ana C; Delgado, Silvia M; Casais, Marilina

    2016-02-29

    An ex-vivo Coeliac Ganglion-Superior Ovarian Nerve-Ovary (CG-SON-O) system from virgin rats in the first proestrous was used to test whether cholinergic stimulation of CG affects oxidative status and steroidogenesis in the ovary. The CG and the O were placed in separate buffered-compartments, connected by the SON, and the CG was stimulated by acetylcholine (Ach). To test a possible role of nitric oxide (NO) in the ovarian response to cholinergic stimulation of CG, aminoguanidine (AG) - an inhibitor of inducible-NO synthase was added to the O compartment. After 180 min incubation, the oxidative status was assessed in O whereas nitrite and steroidogenesis were assessed at 30, 120 and 180 min. Ach in CG decreased the total antioxidant capacity, but increased NO production and protein carbonization in O. Ach stimulation of CG increased estradiol, but decreased progesterone release in O by reducing the mRNAs related to their synthesis and degradation. The addition of AG to the O compartment caused an opposite effect, which was more pronounced in the presence of Ach in the CG compartment than in its absence. These results show that the stimulation of the extrinsic-cholinergic innervation of the O increases the concentration of NO, causes oxidative stress and modulates steroidogenesis in the first rat proestrous.

  20. Stimulation of artemisinin synthesis by combined cerebroside and nitric oxide elicitation in Artemisia annua hairy roots.

    PubMed

    Wang, Jian Wen; Zheng, Li Ping; Zhang, Ben; Zou, Ting

    2009-11-01

    This work examined the accumulation of artemisinin and related secondary metabolism pathways in hairy root cultures of Artemisia annua L. induced by a fungal-derived cerebroside (2S,2'R,3R,3'E,4E,8E)-1-O-beta-D-glucopyranosyl-2-N-(2'-hydroxy-3'-octadecenoyl)-3-hydroxy-9-methyl-4,8-sphingadienine. The presence of the cerebroside induced nitric oxide (NO) burst and artemisinin biosynthesis in the hairy roots. The endogenous NO generation was examined to be involved in the cerebroside-induced biosynthesis of artemisinin by using NO inhibitors, N (omega)-nitro-L-arginine methyl ester and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The gene expression and activity of 3-hydroxy-3-methylglutaryl CoA reductase and 1-deoxy-D-xylulose 5-phosphate synthase were stimulated by the cerebroside, but more strongly by the potentiation of NO. While the mevalonate pathway inhibitor, mevinolin, only partially inhibited the induced artemisinin accumulation, the plastidic 2-C-methyl-D-erythritol 4-phosphate pathway inhibitor, fosmidomycin, nearly arrested artemisinin accumulation induced by cerebroside and the combination elicitation with an NO donor, sodium nitroprusside (SNP). With the potentiation by SNP at 10 microM, the cerebroside elicitor stimulated artemisinin production in 20-day-old hairy root cultures up to 22.4 mg/l, a 2.3-fold increase over the control. These results suggest that cerebroside plays as a novel elicitor and the involvement of NO in the signaling pathway of the elicitor activity for artemisinin biosynthesis.

  1. Localized Plasmon-Stimulated Nanochemistry of Graphene Oxide on a SERS Substrate.

    PubMed

    Ramanauskaite, Lina; Xu, Huizhong; Snitka, Valentinas

    2016-03-16

    In recent years, there has been remarkable progress in the reduction and functionalization of graphene oxide (GO) using nanoparticles and high-energy optical photons. Most of these reactions are carried out in solutions, whereas the local modification of GO on solid substrates still remains a challenge. In this work, we demonstrate the local reduction of GO and its further destruction, leading to the synthesis of polyaromatic hydrocarbons (PAHs) stimulated by localized surface plasmons (LSPs). The reduction of GO and the synthesis of PAHs have been carried out on a substrate designed for surface-enhanced Raman spectroscopy (SERS). We found that LSPs initiate the destruction of water molecules entrapped in the nanogaps between silver nanoparticles after the deposition of GO from the aqueous suspension. It was demonstrated that OH radicals, as a result of water decomposition, initiate the reduction of GO, leading to the synthesis of PAHs. The reactions have been observed in real time by using SERS. The measurement of current-voltage (I-V) characteristics through conductive atomic force microscopy (AFM), recorded in an LSP-stimulated area, have shown the increased electrical conductivity (more than ten times) compared with the conductivity of GO. The synthesis of new compounds in the LSP-stimulated area has been confirmed by the appearance of new peaks in the Raman spectra and nonlinear I-V characteristics typical for PAHs. We show that the used method allows the local modification of electrical properties of GO and controlled nanopattering of organic compounds on the surface. PMID:26728625

  2. The Nitric Oxide Donor SNAP-Induced Amino Acid Neurotransmitter Release in Cortical Neurons. Effects of Blockers of Voltage-Dependent Sodium and Calcium Channels

    PubMed Central

    Merino, José Joaquín; Arce, Carmen; Naddaf, Ahmad; Bellver-Landete, Victor; Oset-Gasque, Maria Jesús; González, María Pilar

    2014-01-01

    Background The discovery that nitric oxide (NO) functions as a signalling molecule in the nervous system has radically changed the concept of neuronal communication. NO induces the release of amino acid neurotransmitters but the underlying mechanisms remain to be elucidated. Findings The aim of this work was to study the effect of NO on amino acid neurotransmitter release (Asp, Glu, Gly and GABA) in cortical neurons as well as the mechanism underlying the release of these neurotransmitters. Cortical neurons were stimulated with SNAP, a NO donor, and the release of different amino acid neurotransmitters was measured by HPLC. The involvement of voltage dependent Na+ and Ca2+ channels as well as cGMP in its mechanism of action was evaluated. Conclusions Our results indicate that NO induces release of aspartate, glutamate, glycine and GABA in cortical neurons and that this release is inhibited by ODQ, an inhibitor of soluble guanylate cyclase. Thus, the NO effect on amino acid neurotransmission could be mediated by cGMP formation in cortical neurons. Our data also demonstrate that the Na+ and Ca2+ voltage- dependent calcium channels are involved in the NO effects on cortical neurons. PMID:24598811

  3. Luminol-dependent photoemission from single neutrophil stimulated by phorbol ester and calcium ionophore--role of degranulation and myeloperoxidase

    SciTech Connect

    Suematsu, M.; Oshio, C.; Miura, S.; Suzuki, M.; Houzawa, S.; Tsuchiya, M.

    1988-08-30

    Luminol-dependent photonic burst from phorbol ester-treated single neutrophil was visually investigated by using an ultrasensitive photonic image intensifier microscope. Neutrophils stimulated by phorbol myristate acetate (0.1 microgram/ml) alone produced a negligible level of photonic activities in the presence of luminol (10 micrograms/ml). The additional application of 0.1 microM Ca2+ ionophore A23187 induced explosive changes of photonic burst corresponding to the distribution of neutrophils, and these photonic activities were gradually spread to extracellular space. Sodium azide, which prevents myeloperoxidase activity, inhibited Ca2+ ionophore-induced photonic burst from phorbol ester-treated neutrophil. These findings suggest a prerequisite role of degranulation and myeloperoxidase release in luminol-dependent photoemission from stimulated neutrophils.

  4. Electrical stimulation induces calcium-dependent up-regulation of neuregulin-1β in dystrophic skeletal muscle cell lines.

    PubMed

    Juretić, Nevenka; Jorquera, Gonzalo; Caviedes, Pablo; Jaimovich, Enrique; Riveros, Nora

    2012-01-01

    Duchenne muscular dystrophy (DMD) is a neuromuscular disease originated by reduced or no expression of dystrophin, a cytoskeletal protein that provides structural integrity to muscle fibres. A promising pharmacological treatment for DMD aims to increase the level of a structural dystrophin homolog called utrophin. Neuregulin-1 (NRG-1), a growth factor that potentiates myogenesis, induces utrophin expression in skeletal muscle cells. Microarray analysis of total gene expression allowed us to determine that neuregulin-1β (NRG-1β) is one of 150 differentially expressed genes in electrically stimulated (400 pulses, 1 ms, 45 Hz) dystrophic human skeletal muscle cells (RCDMD). We investigated the effect of depolarization, and the involvement of intracellular Ca(2+) and PKC isoforms on NRG-1β expression in dystrophic myotubes. Electrical stimulation of RCDMD increased NRG-1β mRNA and protein levels, and mRNA enhancement was abolished by actinomycin D. NRG-1β transcription was inhibited by BAPTA-AM, an intracellular Ca(2+) chelator, and by inhibitors of IP(3)-dependent slow Ca(2+) transients, like 2-APB, Ly 294002 and Xestospongin B. Ryanodine, a fast Ca(2+) signal inhibitor, had no effect on electrical stimulation-induced expression. BIM VI (general inhibitor of PKC isoforms) and Gö 6976 (specific inhibitor of Ca(2+)-dependent PKC isoforms) abolished NRG-1β mRNA induction. Our results suggest that depolarization induced slow Ca(2+) signals stimulate NRG-1β transcription in RCDMD cells, and that Ca(2+)-dependent PKC isoforms are involved in this process. Based on utrophin's ability to partially compensate dystrophin disfunction, knowledge on the mechanism involved on NRG-1 up-regulation could be important for new therapeutic strategies design. PMID:22613991

  5. Surface properties of calcium and magnesium oxide nanopowders grafted with unsaturated carboxylic acids studied with inverse gas chromatography.

    PubMed

    Maciejewska, Magdalena; Krzywania-Kaliszewska, Alicja; Zaborski, Marian

    2012-09-28

    Inverse gas chromatography (IGC) was applied at infinite dilution to evaluate the surface properties of calcium and magnesium oxide nanoparticles and the effect of surface grafted unsaturated carboxylic acid on the nanopowder donor-acceptor characteristics. The dispersive components (γ(s)(D)) of the free energy of the nanopowders were determined by Gray's method, whereas their tendency to undergo specific interactions was estimated based on the electron donor-acceptor approach presented by Papirer. The calcium and magnesium oxide nanoparticles exhibited high surface energies (79 mJ/m² and 74 mJ/m², respectively). Modification of nanopowders with unsaturated carboxylic acids decreased their specific adsorption energy. The lowest value of γ(s)(D) was determined for nanopowders grafted with undecylenic acid, approximately 55 mJ/m². The specific interactions were characterised by the molar free energy (ΔG(A)(SP)) and molar enthalpy (ΔH(A)(SP)) of adsorption as well as the donor and acceptor interaction parameters (K(A), K(D)). PMID:22907042

  6. Effect of endogenous and exogenous nitric oxide on calcium sparks as targets for vasodilation in rat cerebral artery.

    PubMed

    Mandalà, Maurizio; Heppner, Thomas J; Bonev, Adrian D; Nelson, Mark T

    2007-02-01

    The potent vasodilator nitric oxide (NO), produced mainly by the endothelium, acts through a BK(Ca)-dependent mechanism to increase the frequency of calcium sparks (Ca(2+) sparks) in myocyte isolated from rat cerebral arteries. Our present aim has been to assess the role of endogenous and exogenous NO on the Ca(2+) sparks through ryanodine-sensitive channels in the sarcoplasmic reticulum of an intact artery. Calcium sparks, detected with fluo-4 and laser scanning confocal microscopy, were examined in isolated pressurized rat posterior cerebral arteries with (intact) and without endothelium (denuded). Addition of the NO donor, DEA-NONOate (N-(2-aminoethyl)-N-(2-hydroxy-2-nitrosohydrazino)-1,2-ethylenediamine), did not change the amplitude and frequency of Ca(2+) sparks in the intact artery. However, inhibition of nitric oxide synthase with N-omega-nitro-L-arginine or removal of endothelium reduced Ca(2+) sparks frequency by about 50%. Under these conditions (i.e., absence of endogenous NO production), DEA-NONOate, increased Ca(2+) spark frequency 3- to 4-fold. These results suggest that endothelial NO modulates local Ca(2+) release events in the arterial smooth muscle and that this mechanism may contribute to the actions of nitrovasodilators.

  7. Calcium-borosilicate glass-ceramics wasteforms to immobilize rare-earth oxide wastes from pyro-processing

    NASA Astrophysics Data System (ADS)

    Kim, Miae; Heo, Jong

    2015-12-01

    Glass-ceramics containing calcium neodymium(cerium) oxide silicate [Ca2Nd8-xCex(SiO4)6O2] crystals were fabricated for the immobilization of radioactive wastes that contain large portions of rare-earth ions. Controlled crystallization of alkali borosilicate glasses by heating at T ≥ 750 °C for 3 h formed hexagonal Ca-silicate crystals. Maximum lanthanide oxide waste loading was >26.8 wt.%. Ce and Nd ions were highly partitioned inside Ca-silicate crystals compared to the glass matrix; the rare-earth wastes are efficiently immobilized inside the crystalline phases. The concentrations of Ce and Nd ions released in a material characterization center-type 1 test were below the detection limit (0.1 ppb) of inductively coupled plasma mass spectroscopy. Normalized release values performed by a product consistency test were 2.64·10-6 g m-2 for Ce ion and 2.19·10-6 g m-2 for Nd ion. Results suggest that glass-ceramics containing calcium neodymium(cerium) silicate crystals are good candidate wasteforms for immobilization of lanthanide wastes generated by pyro-processing.

  8. Potentiation by nitric oxide synthase inhibitor and calcium channel blocker of aspartame-induced antinociception in the mouse formalin test.

    PubMed

    Abdollahi, M; Nikfar, S; Abdoli, N

    2001-04-01

    By applying a 12 day regimen of the non-calorific sweetener, aspartame, in combination with representative compounds of the calcium channel blocker and nitric oxide synthase inhibitor, we tried to investigate using a formalin-test in mice the relative role of aspartame on pain and its mechanism of action. Verapamil (2, 3.5, 5, 7.5 mg/kg) induced significant (P < 0.01) antinociception in both phases of the formalin test. L-Nitro-arginine-methyl-ester (L-NAME) at the doses used, induced significant (P < 0.01) antinociception in early phase (1, 2, 5, 10 mg/kg) and late phase (5, 10 mg/kg). Twelve days of treatment in animals by aspartame (0.16% w/v) significantly induced antinociception in both phases of the formalin test. Both verapamil (5 mg/kg) and L-NAME (10 mg/kg) significantly (P < 0.01) potentiated aspartame-induced antinociception in both phases of formalin test. The present findings support the hypothesis that the activation of NMDA receptors by aspartame modulates pain-related behaviour via a nitric oxide/cGMP/glutamate release cascade. It is concluded that aspartame would be a good analgesic agent if it would be used in combination with a calcium channel blocker or NOS inhibitor.

  9. Alternaric acid stimulates phosphorylation of His-tagged RiCDPK2, a calcium-dependent protein kinase in potato plants.

    PubMed

    Hassan, A; Okuta, T; Kato, M; Hatsugai, N; Sano, Y; Ishimori, T; Okazaki, K; Doullah, M A; Shah, M M

    2012-08-16

    Calcium-dependent protein kinases (CDPK) are an essential component of plant defense mechanisms against pathogens. We investigated the effect of alternaric acid, a host-specific toxin produced by the plant fungal pathogen Alternaria solani (Pleosporaceae), on a putative plasma membrane and cytosolic kinase RiCDPK2 of potato (Solanum tuberosum) and on hypersensitive cell death of host potato cells. Alternaric acid, in the presence of Ca²⁺ and Mg²⁺, stimulated in vitro phosphorylation of His-tagged RiCDPK2, a Ca²⁺-dependent protein kinase found in potato plants. We concluded that Ca²⁺ and Mg²⁺ play an important role in the interaction between alternaric acid and RiCDPK2. Based on our observations, alternaric acid regulates RiCDPK2 kinase during the infection process in an interaction between host and A. solani, leading to the inhibition of hypersensitive cell death in the host. We suggest that alternaric acid is a primary determinant by which A. solani stimulates CDPK activity in the host, suppressing hypersensitive cell death.

  10. Impact of free calcium oxide content of fly ash on dust and sulfur dioxide emissions in a lignite-fired power plant

    SciTech Connect

    Dimitrios Sotiropoulos; Andreas Georgakopoulos; Nestoras Kolovos

    2005-07-01

    Emitted pollutants from the Agios Dimitrios lignite-fired power plant in northern Greece show a very strong linear correlation with the free calcium oxide content of the lignite ash. Dust (fly ash) emissions are positively correlated to free calcium oxide content, whereas sulfur dioxide (SO{sub 2}) emissions are negatively correlated. As a result, at present, the Agios Dimitrios Power Plant operates very strictly within the legislative limits on atmospheric particulate emission. In the study reported, the factors to be considered in assessing the impact of lignite combustion on the environment are presented and evaluated statistically. The ash appears to have a remarkable SO{sub 2} natural dry scrubbing capability when the free calcium oxide content ranges between 4 and 7%. Precipitator operating problems attributable to high ash resistivity can be overcome by injecting sulfur trioxide to reduce the ash resistivity, with, of course, a probable increase in operating costs. 27 refs., 7 figs., 1 tab.

  11. Expression of inducible nitric oxide synthase by stimulated macrophages correlates with their antihistoplasma activity.

    PubMed Central

    Lane, T E; Otero, G C; Wu-Hsieh, B A; Howard, D H

    1994-01-01

    The antihistoplasma activity of recombinant murine gamma interferon (rMuIFN-gamma)-treated macrophages of the RAW 264.7 cell line depends on the generation of nitric oxide (NO.) from L-arginine. Macrophages of the P388D1 cell line treated with rMuIFN-gamma do not produce NO. or inhibit the intracellular growth of Histoplasma capsulatum. NO. is generated by the inducible enzyme nitric oxide synthase (iNOS) formed by stimulated macrophages. Northern (RNA) blot analysis of RAW 264.7 cells revealed the expression of iNOS mRNA after exposure to rMuIFN-gamma. In contrast, rMuIFN-gamma-treated P388D1 cells did not produce detectable levels of iNOS. These data suggest that the failure of P388D1 cells to generate NO. and to restrict the intracellular growth of H. capsulatum is due to a lack of expression of iNOS following treatment with rMuIFN-gamma. Images PMID:7510670

  12. Nutrient input influences fungal community composition and size and can stimulate manganese (II) oxidation in caves.

    PubMed

    Carmichael, Sarah K; Zorn, Bryan T; Santelli, Cara M; Roble, Leigh A; Carmichael, Mary J; Bräuer, Suzanna L

    2015-08-01

    Little is known about the fungal role in biogeochemical cycling in oligotrophic ecosystems. This study compared fungal communities and assessed the role of exogenous carbon on microbial community structure and function in two southern Appalachian caves: an anthropogenically impacted cave and a near-pristine cave. Due to carbon input from shallow soils, the anthropogenically impacted cave had an order of magnitude greater fungal and bacterial quantitative-polymerase chain reaction (qPCR) gene copy numbers, had significantly greater community diversity, and was dominated by ascomycotal phylotypes common in early phase, labile organic matter decomposition. Fungal assemblages in the near-pristine cave samples were dominated by Basidiomycota typically found in deeper soils (and/or in late phase, recalcitrant organic matter decomposition), suggesting more oligotrophic conditions. In situ carbon and manganese (II) [Mn(II)] addition over 10 weeks resulted in growth of fungal mycelia followed by increased Mn(II) oxidation. A before/after comparison of the fungal communities indicated that this enrichment increased the quantity of fungal and bacterial cells, yet decreased overall fungal diversity. Anthropogenic carbon sources can therefore dramatically influence the diversity and quantity of fungi, impact microbial community function, and stimulate Mn(II) oxidation, resulting in a cascade of changes that can strongly influence nutrient and trace element biogeochemical cycles in karst aquifers.

  13. Bile acid induced colonic irritation stimulates intracolonic nitric oxide release in humans.

    PubMed Central

    Casellas, F; Mourelle, M; Papo, M; Guarner, F; Antolin, M; Armengol, J R; Malagelada, J R

    1996-01-01

    AIM--To measure the intracolonic release of nitric oxide end products (nitrates plus nitrites) and eicosanoids in response to intraluminal irritation with deoxycholic acid (DCA). PATIENTS--Seven patients with irritable bowel syndrome. METHODS--The left colon was perfused with a solution with or without 3 mM deoxycholic acid. Aspirates were assayed for eicosanoids by specific radioimmuno-assay, and for nitrates plus nitrites by the Griess reaction. To confirm that stimulated colonic mucosa can produce nitric oxide (NO), ancillary studies were performed in vitro using samples of normal mucosa obtained from five surgically resected colons. Samples were incubated for 30 minutes in Kreb's solution, 3 mM DCA or DCA with 1 mM L-nitro-arginine-methyl-ester (L-NAME) to inhibit the NO synthase. Finally, NO synthase activity was measured in five samples of human colonic mucosa. RESULTS--Intracolonic release of nitrates plus nitrites was basally undetectable in six of seven patients. Bile acid considerably increased the release of prostaglandin E2 and nitrates plus nitrites (p < 0.01). By contrast, no increase in thromboxane and leukotriene was seen. In vitro mucosal incubation with DCA increased the production of NO synthase products, which was blocked by L-NAME. Activity of Ca+2 independent NO synthase was detectable in four of five samples of human colonic mucosa. CONCLUSION--The human colonic mucosa responds to bile acid induced irritation by a surge in NO generation via NO synthase. PMID:8707118

  14. Breaking the apple embryo dormancy by nitric oxide involves the stimulation of ethylene production.

    PubMed

    Gniazdowska, Agnieszka; Dobrzyńska, Urszula; Babańczyk, Tomasz; Bogatek, Renata

    2007-03-01

    Mature seeds of apple (Mallus domestica Borb. cv. Antonówka) are dormant and do not germinate unless their dormancy is removed by several weeks of moist-cold treatment. We investigated the effect of short-term (3 h) nitric oxide (NO) pretreatment on breaking of apple embryonic dormancy expressed as inhibition of germination and morphological abnormalities of young seedlings. Imbibition of embryos isolated from dormant apple seeds with sodium nitroprusside (SNP) or S-nitroso,N-acetyl penicillamine (SNAP) as NO donors resulted in enhanced germination. Moreover, NO treatment removed morphological abnormalities of seedlings developing from dormant embryo. The NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-teramethylimidazoline-1-oxyl-3 oxide (cPTIO) removed the above effects. NO-mediated breaking of embryonic dormancy correlated well with enhanced ethylene production. Inhibitor of ethylene synthesis (AOA) reversed the stimulatory effect of NO donors on embryo germination. Additionally SNP reduced embryo sensitivity to exogenously applied ABA ensuing dormancy breakage. We can conclude that NO acts as a regulatory factor included in the control of apple embryonic dormancy breakage by stimulation of ethylene biosynthesis.

  15. Sequential reductive and oxidative biodegradation of chloroethenes stimulated in a coupled bioelectro-process.

    PubMed

    Lohner, Svenja T; Becker, Dirk; Mangold, Klaus-Michael; Tiehm, Andreas

    2011-08-01

    This article for the first time demonstrates successful application of electrochemical processes to stimulate sequential reductive/oxidative microbial degradation of perchloroethene (PCE) in mineral medium and in contaminated groundwater. In a flow-through column system, hydrogen generation at the cathode supported reductive dechlorination of PCE to cis-dichloroethene (cDCE), vinyl chloride (VC), and ethene (ETH). Electrolytically generated oxygen at the anode allowed subsequent oxidative degradation of the lower chlorinated metabolites. Aerobic cometabolic degradation of cDCE proved to be the bottleneck for complete metabolite elimination. Total removal of chloroethenes was demonstrated for a PCE load of approximately 1.5 μmol/d. In mineral medium, long-term operation with stainless steel electrodes was demonstrated for more than 300 days. In contaminated groundwater, corrosion of the stainless steel anode occurred, whereas DSA (dimensionally stable anodes) proved to be stable. Precipitation of calcareous deposits was observed at the cathode, resulting in a higher voltage demand and reduced dechlorination activity. With DSA and groundwater from a contaminated site, complete degradation of chloroethenes in groundwater was obtained for two months thus demonstrating the feasibility of the sequential bioelectro-approach for field application.

  16. Nutrient input influences fungal community composition and size and can stimulate manganese (II) oxidation in caves.

    PubMed

    Carmichael, Sarah K; Zorn, Bryan T; Santelli, Cara M; Roble, Leigh A; Carmichael, Mary J; Bräuer, Suzanna L

    2015-08-01

    Little is known about the fungal role in biogeochemical cycling in oligotrophic ecosystems. This study compared fungal communities and assessed the role of exogenous carbon on microbial community structure and function in two southern Appalachian caves: an anthropogenically impacted cave and a near-pristine cave. Due to carbon input from shallow soils, the anthropogenically impacted cave had an order of magnitude greater fungal and bacterial quantitative-polymerase chain reaction (qPCR) gene copy numbers, had significantly greater community diversity, and was dominated by ascomycotal phylotypes common in early phase, labile organic matter decomposition. Fungal assemblages in the near-pristine cave samples were dominated by Basidiomycota typically found in deeper soils (and/or in late phase, recalcitrant organic matter decomposition), suggesting more oligotrophic conditions. In situ carbon and manganese (II) [Mn(II)] addition over 10 weeks resulted in growth of fungal mycelia followed by increased Mn(II) oxidation. A before/after comparison of the fungal communities indicated that this enrichment increased the quantity of fungal and bacterial cells, yet decreased overall fungal diversity. Anthropogenic carbon sources can therefore dramatically influence the diversity and quantity of fungi, impact microbial community function, and stimulate Mn(II) oxidation, resulting in a cascade of changes that can strongly influence nutrient and trace element biogeochemical cycles in karst aquifers. PMID:25865809

  17. Theta-Burst Stimulation of Hippocampal Slices Induces Network-Level Calcium Oscillations and Activates Analogous Gene Transcription to Spatial Learning

    PubMed Central

    O'Connor, John J.; Murphy, Keith J.

    2014-01-01

    Over four decades ago, it was discovered that high-frequency stimulation of the dentate gyrus induces long-term potentiation (LTP) of synaptic transmission. LTP is believed to underlie how we process and code external stimuli before converting it to salient information that we store as 'memories'. It has been shown that rats performing spatial learning tasks display theta-frequency (3–12 Hz) hippocampal neural activity. Moreover, administering theta-burst stimulation (TBS) to hippocampal slices can induce LTP. TBS triggers a sustained rise in intracellular calcium [Ca2+]i in neurons leading to new protein synthesis important for LTP maintenance. In this study, we measured TBS-induced [Ca2+]i oscillations in thousands of cells at increasing distances from the source of stimulation. Following TBS, a calcium wave propagates radially with an average speed of 5.2 µm/s and triggers multiple and regular [Ca2+]i oscillations in the hippocampus. Interestingly, the number and frequency of [Ca2+]i fluctuations post-TBS increased with respect to distance from the electrode. During the post-tetanic phase, 18% of cells exhibited 3 peaks in [Ca2+]i with a frequency of 17 mHz, whereas 2.3% of cells distributed further from the electrode displayed 8 [Ca2+]i oscillations at 33 mHz. We suggest that these observed [Ca2+]i oscillations could lead to activation of transcription factors involved in synaptic plasticity. In particular, the transcription factor, NF-κB, has been implicated in memory formation and is up-regulated after LTP induction. We measured increased activation of NF-κB 30 min post-TBS in CA1 pyramidal cells and also observed similar temporal up-regulation of NF-κB levels in CA1 neurons following water maze training in rats. Therefore, TBS of hippocampal slice cultures in vitro can mimic the cell type-specific up-regulations in activated NF-κB following spatial learning in vivo. This indicates that TBS may induce similar transcriptional changes to spatial learning

  18. Stimulation and oxidative catalytic inactivation of thermolysin by copper.Cys-Gly-His-Lys.

    PubMed

    Gokhale, Nikhil H; Bradford, Seth; Cowan, J A

    2007-09-01

    [Cu(2+).Cys-Gly-His-Lys] stimulates thermolysin (TLN) activity at low concentration (below 10 microM) and inhibits the enzyme at higher concentration, with binding affinities of 2.0 and 4.9 microM, respectively. The metal-free Cys-Gly-His-Lys peptide also stimulates TLN activity, with an apparent binding affinity of 2.2 microM. Coordination of copper through deprotonated imine nitrogens, the histidyl nitrogen, and the free N-terminal amino group is consistent with the characteristic absorption spectrum of a Cu(2+)-amino-terminal copper and nickel binding motif (lambda (max) approximately 525 nm). The lack of thiol coordination is suggested by both the absence of a thiol to Cu(2+) charge transfer band and electrochemical studies, since the electrode potential (vs. Ag/AgCl) 0.84 V (DeltaE = 92 mV) for the Cu(3+/2+) redox couple obtained for [Cu(2+).Cys-Gly-His-Lys] was found to be in close agreement with that of a related complex [Cu(2+).Lys-Gly-His-Lys](+) (0.84 V, DeltaE = 114 mV). The N-terminal cysteine appears to be available as a zinc-anchoring residue and plays a critical functional role since the [Cu(2+).Lys-Gly-His-Lys](+) homologue exhibits neither stimulation nor inhibition of TLN. Under oxidizing conditions (ascorbate/O(2)) the catalyst is shown to mediate the complete irreversible inactivation of TLN at concentrations where enzyme activity would otherwise be stimulated. The observed rate constant for inactivation of TLN activity was determined as k (obs) = 7.7 x 10(-2) min(-1), yielding a second-order rate constant of (7.7 +/- 0.9) x 10(4) M(-1) min(-1). Copper peptide mediated generation of reactive oxygen species that subsequently modify active-site residues is the most likely pathway for inactivation of TLN rather than cleavage of the peptide backbone. PMID:17618468

  19. Heat stress stimulates nitric oxide production in Symbiodinium microadriaticum: a possible linkage between nitric oxide and the coral bleaching phenomenon.

    PubMed

    Bouchard, Josée Nina; Yamasaki, Hideo

    2008-04-01

    Nitric oxide (NO) is a gas displaying multiple physiological functions in plants, animals and bacteria. The enzymes nitrate reductase and NO synthase have been suggested to be involved in the production of NO in plants and algae, but the implication of those enzymes in NO production under physiological conditions remains obscure. Symbiodinium microadriaticum, commonly referred to as zooxanthellae, is a marine microalga commonly found in symbiotic association with a cnidarian host including reef-building corals. Here we demonstrate NO production in zooxanthellae upon supplementation of either sodium nitrite or L-arginine as a substrate. The nitrite-dependent NO production was detected electrochemically and confirmed by the application of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a specific NO scavenger. Cells stained with the diaminofluorescein, DAF-2 DA, an NO fluorescent probe, showed an increase in fluorescence intensity upon supplementation of both sodium nitrite and L-arginine. Microscopic observations of DAF-stained cells verified that NO was produced inside the cells. NO production in S. microadriaticum was found to increase upon exposure of cells to an acute heat stress which also caused a decline in the photosynthetic efficiency of PSII (F(v)/F(m)). This study provides substantial evidence to confirm that zooxanthellae can synthesize NO even when they are not in a symbiotic association with a coral host. The increase in NO production at high temperatures suggests that heat stress stimulates the microalgal NO production in a temperature-dependent manner. The implications of these findings are discussed in the light of the coral bleaching phenomenon which is associated with elevated sea surface temperature due to global warming.

  20. Stimulation of colonic mucosal growth associated with oxidized redox status in rats.

    PubMed

    Tian, Junqiang; Washizawa, Naohiro; Gu, Li H; Levin, Marc S; Wang, Lihua; Rubin, Deborah C; Mwangi, Simon; Srinivasan, Shanthi; Gao, Yuhao; Jones, Dean P; Ziegler, Thomas R

    2007-03-01

    Limited data in animal models suggest that colonic mucosa undergoes adaptive growth following massive small bowel resection (SBR). In vitro data suggest that intestinal cell growth is regulated by reactive oxygen species and redox couples [e.g., glutathione (GSH)/glutathione disulfide (GSSG) and cysteine (Cys)/cystine (CySS) redox]. We investigated the effects of SBR and alterations in redox on colonic growth indexes in rats after either small bowel transection (TX) or 80% midjejunoileal resection (RX). Rats were pair fed +/- blockade of endogenous GSH synthesis with buthionine sulfoximine (BSO). Indexes of colonic growth, proliferation, and apoptosis and GSH/GSSG and Cys/CySS redox potentials (E(h)) were determined. RX significantly increased colonic crypt depth, number of cells per crypt, and epithelial cell proliferation [crypt cell bromodeoxyuridine (BrdU) incorporation]. Administration of BSO markedly decreased colonic mucosal GSH, GSSG, and Cys concentrations in both TX and RX groups, with a resultant oxidation of GSH/GSSG and Cys/CySS E(h). BSO did not alter colonic crypt cell apoptosis but significantly increased all colonic mucosal growth indexes (crypt depth, cells/crypt, and BrdU incorporation) in both TX and RX groups in a time- and dose-dependent manner. BSO significantly decreased plasma GSH and GSSG, oxidized GSH/GSSG E(h), and increased plasma Cys and CySS concentrations. Collectively, these data provide in vivo evidence indicating that oxidized colonic mucosal redox status stimulates colonic mucosal growth in rats. The data also suggest that GSH is required to maintain normal colonic and plasma Cys/CySS homeostasis in these animal models.

  1. Role of calcium in insulin-stimulated NaC1 transport in medullary thick ascending limb.

    PubMed

    Ito, O; Kondo, Y; Takahashi, N; Omata, K; Abe, K

    1995-08-01

    It has been reported that insulin stimulates directly NaCl transport in the rabbit medullary thick ascending limb (MTAL) [O. Ito, Y. Kondo, N. Takahashi, K. Kudo, Y. Imai, K. Omata, and K. Abe. Am. J. Physiol. 267 (Renal Fluid Electrolyte Physiol. 36): F265-F270, 1994]. In the present investigation, we evaluated the role of Ca2+ in insulin-stimulated NaCl transport in rabbit MTAL by in vitro microperfusion methods. In control experiments, insulin increases transepithelial voltage (Vte) and net lumen-to-bath Cl-flux (JCl). The effects of insulin on Vte and JCl in a Ca2+ -free solution containing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N' -tetraacetic acid did not differ from those in a Ca2+ -containing control solution. Direct measurements of cytosolic free Ca2+ ([Ca2+]i) with fura 2 fluorescence showed that insulin caused no detectable change in [Ca2+]i in MTAL cells. Chelation of intracellular Ca2+ with the acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid inhibited the actions of insulin in Vte and JCl without affecting basal values. We examined further whether calmodulin is also involved in insulin-stimulated NaCl transport in MTAL using two dissimilar inhibitors of calmodulin, trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7). TFP and W-7 inhibited the action of insulin in a dose-dependent manner, with maximal inhibition of both agents of > 90%. The half-maximal inhibition by TFP and W-7 was approximately 50 and 100 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Calcium-sensing receptor stimulates Cl(-)- and SCFA-dependent but inhibits cAMP-dependent HCO3(-) secretion in colon.

    PubMed

    Tang, Lieqi; Peng, Minzhi; Liu, Li; Chang, Wenhan; Binder, Henry J; Cheng, Sam X

    2015-05-15

    Colonic bicarbonate (HCO3(-)) secretion is a well-established physiological process that is closely linked to overall fluid and electrolyte movement in the mammalian colon. These present studies show that extracellular calcium-sensing receptor (CaSR), a fundamental mechanism for sensing and regulating ionic and nutrient compositions of extracellular milieu in the small and large intestine, regulates HCO3(-) secretion. Basal and induced HCO3(-) secretory responses to CaSR agonists were determined by pH stat techniques used in conjunction with short-circuit current measurements in mucosa from rat distal colon mounted in Ussing chambers. R568, a specific CaSR activator, stimulated lumen Cl(-)- and short-chain fatty acid (SCFA)-dependent HCO3(-) secretion but inhibited cyclic nucleotide-activated HCO3(-) secretion. Consequently, at physiological conditions (either at basal or during lumen acid challenge) when electroneutral Cl(-)/HCO3(-) and SCFA/HCO3(-) exchangers dominate, CaSR stimulates HCO3(-) secretion; in contrast, in experimental conditions that stimulate fluid and HCO3(-) secretion, e.g., when forskolin activates electrogenic cystic fibrosis transmembrane conductance regulator-mediated HCO3(-) conductance, CaSR activation inhibits HCO3(-) secretion. Corresponding changes in JHCO3 (μeq·h(-1)·cm(-2), absence vs. presence of R568) were 0.18 ± 0.03 vs. 0.31 ± 0.08 under basal nonstimulated conditions and 1.85 ± 0.23 vs. 0.45 ± 0.06 under forskolin-stimulated conditions. Similarly, activation of CaSR by R568 stimulated Cl(-)- and SCFA-dependent HCO3(-) secretion and inhibited cAMP-dependent HCO3(-) secretion in colon mucosa of wild-type mice; such effects were abolished in CaSR-null mice. These results suggest a new paradigm for regulation of intestinal ion transport in which HCO3(-) secretion may be fine-tuned by CaSR in accordance with nutrient availability and state of digestion and absorption. The ability of CaSR agonists to inhibit secretagogue

  3. Transient hypoxia stimulates mitochondrial biogenesis in brain subcortex by a neuronal nitric oxide synthase-dependent mechanism

    EPA Science Inventory

    The adaptive mechanisms that protect brain metabolism during and after hypoxia, for instance, during hypoxic preconditioning, are coordinated in part by nitric oxide (NO). We tested the hypothesis that acute transient hypoxia stimulates NO synthase (NOS)-activated mechanisms of m...

  4. Rac-mediated Stimulation of Phospholipase Cγ2 Amplifies B Cell Receptor-induced Calcium Signaling*♦

    PubMed Central

    Walliser, Claudia; Tron, Kyrylo; Clauss, Karen; Gutman, Orit; Kobitski, Andrei Yu.; Retlich, Michael; Schade, Anja; Röcker, Carlheinz; Henis, Yoav I.; Nienhaus, G. Ulrich; Gierschik, Peter

    2015-01-01

    The Rho GTPase Rac is crucially involved in controlling multiple B cell functions, including those regulated by the B cell receptor (BCR) through increased cytosolic Ca2+. The underlying molecular mechanisms and their relevance to the functions of intact B cells have thus far remained unknown. We have previously shown that the activity of phospholipase Cγ2 (PLCγ2), a key constituent of the BCR signalosome, is stimulated by activated Rac through direct protein-protein interaction. Here, we use a Rac-resistant mutant of PLCγ2 to functionally reconstitute cultured PLCγ2-deficient DT40 B cells and to examine the effects of the Rac-PLCγ2 interaction on BCR-mediated changes of intracellular Ca2+ and regulation of Ca2+-regulated and nuclear-factor-of-activated-T-cell-regulated gene transcription at the level of single, intact B cells. The results show that the functional Rac-PLCγ2 interaction causes marked increases in the following: (i) sensitivity of B cells to BCR ligation; (ii) BCR-mediated Ca2+ release from intracellular stores; (iii) Ca2+ entry from the extracellular compartment; and (iv) nuclear translocation of the Ca2+-regulated nuclear factor of activated T cells. Hence, Rac-mediated stimulation of PLCγ2 activity serves to amplify B cell receptor-induced Ca2+ signaling. PMID:25903139

  5. The reduced state of the plastoquinone pool is required for chloroplast-mediated stomatal closure in response to calcium stimulation.

    PubMed

    Wang, Wen-Hua; He, En-Ming; Chen, Juan; Guo, Ying; Chen, Juan; Liu, Xiang; Zheng, Hai-Lei

    2016-04-01

    Besides their participation in photosynthesis, leaf chloroplasts function in plant responses to stimuli, yet how they direct stimulus-induced stomatal movement remains elusive. Here, we showed that over-reduction of the plastoquinone (PQ) pool by dibromothymoquinone (DBMIB) was closely associated with stomatal closure in plants which required chloroplastic H2O2 generation in the mesophyll. External application of H2 O2 reduced the PQ pool, whereas the cell-permeable reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) reversed the DBMIB-induced over-reduction of the PQ pool and stomatal closure. Mesophyll chloroplasts are key players of extracellular Ca(2+) (Ca(2+)o)-induced stomatal closure, but when treated with either 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) or NAC they failed to facilitate Ca(2+)o-induced stomatal closure due to the inhibition of chloroplastic H2 O2 synthesis in mesophyll. Similarly, the Arabidopsis electron transfer chain-related mutants npq4-1, stn7 and cas-1 exhibited diverse responses to Ca(2+)o or DBMIB. Transcriptome analysis also demonstrated that the PQ pool signaling pathway shared common responsive genes with the H2 O2 signaling pathway. These results implicated a mechanism for chloroplast-mediated stomatal closure involving the generation of mesophyll chloroplastic H2O2 based on the reduced state of the PQ pool, which is calcium-sensing receptor (CAS) and LHCII phosphorylation dependent.

  6. Micro-arc oxidation as a tool to develop multifunctional calcium-rich surfaces for dental implant applications.

    PubMed

    Ribeiro, A R; Oliveira, F; Boldrini, L C; Leite, P E; Falagan-Lotsch, P; Linhares, A B R; Zambuzzi, W F; Fragneaud, B; Campos, A P C; Gouvêa, C P; Archanjo, B S; Achete, C A; Marcantonio, E; Rocha, L A; Granjeiro, J M

    2015-09-01

    Titanium (Ti) is commonly used in dental implant applications. Surface modification strategies are being followed in last years in order to build Ti oxide-based surfaces that can fulfill, simultaneously, the following requirements: induced cell attachment and adhesion, while providing a superior corrosion and tribocorrosion performance. In this work micro-arc oxidation (MAO) was used as a tool for the growth of a nanostructured bioactive titanium oxide layer aimed to enhance cell attachment and adhesion for dental implant applications. Characterization of the surfaces was performed, in terms of morphology, topography, chemical composition and crystalline structure. Primary human osteoblast adhesion on the developed surfaces was investigated in detail by electronic and atomic force microscopy as well as immunocytochemistry. Also an investigation on the early cytokine production was performed. Results show that a relatively thick hybrid and graded oxide layer was produced on the Ti surface, being constituted by a mixture of anatase, rutile and amorphous phases where calcium (Ca) and phosphorous (P) were incorporated. An outermost nanometric-thick amorphous oxide layer rich in Ca was present in the film. This amorphous layer, rich in Ca, improved fibroblast viability and metabolic activity as well as osteoblast adhesion. High-resolution techniques allowed to understand that osteoblasts adhered less in the crystalline-rich regions while they preferentially adhere and spread over in the Ca-rich amorphous oxide layer. Also, these surfaces induce higher amounts of IFN-γ cytokine secretion, which is known to regulate inflammatory responses, bone microarchitecture as well as cytoskeleton reorganization and cellular spreading. These surfaces are promising in the context of dental implants, since they might lead to faster osseointegration. PMID:26046283

  7. Low-vitamin E diet exacerbates calcium oxalate crystal formation via enhanced oxidative stress in rat hyperoxaluric kidney.

    PubMed

    Huang, Ho-Shiang; Ma, Ming-Chieh; Chen, Jun

    2009-01-01

    Vitamin E was previously reported to reduce calcium oxalate (CaOx) crystal formation. This study explored whether vitamin E deficiency affects intrarenal oxidative stress and accelerates crystal deposition in hyperoxaluria. The control (C) group of rats received a standard diet and drinking water, while the experimental groups received 0.75% ethylene glycol (EG) in drinking water for 42 days. Of the latter, one group received a standard diet (EG group), one received a low-vitamin E (LE) diet (EG+LE group), and the last received an LE diet with vitamin E supplement (4 mg) (EG+LE+E group). The C+LE and C+LE+E groups were the specific controls for the last two experimental groups, respectively. In a separate experiment, EG and EG+LE rats were studied on days 3-42 to examine the temporal relationship between oxidative change and crystal formation. Urinary biochemistry and activity/levels of antioxidative and oxidative enzymes in glomeruli and tubulointerstitial specimens (TIS) were examined. In EG rats, CaOx crystal accumulation was associated with low antioxidative enzyme activity in TIS and with increased oxidative enzyme expression in glomeruli. In the EG+LE group, marked changes in antioxidative and oxidative enzyme levels were seen and correlated with massive CaOx deposition and tubular damage. The increased oxidative stress seen with EG+LE treatment was largely reversed by vitamin E supplementation. A temporal study showed that decrease in antioxidative defense and increased free radical formation in the EG+LE group occurred before crystal deposition. This study shows that low vitamin E disrupts the redox balance and causes cell death, thereby favoring crystal formation.

  8. Trolox-Sensitive Reactive Oxygen Species Regulate Mitochondrial Morphology, Oxidative Phosphorylation and Cytosolic Calcium Handling in Healthy Cells

    PubMed Central

    Distelmaier, Felix; Valsecchi, Federica; Forkink, Marleen; van Emst-de Vries, Sjenet; Swarts, Herman G.; Rodenburg, Richard J.T.; Verwiel, Eugène T.P.; Smeitink, Jan A.M.; Willems, Peter H.G.M.

    2012-01-01

    Abstract Aims: Cell regulation by signaling reactive oxygen species (sROS) is often incorrectly studied through extracellular oxidant addition. Here, we used the membrane-permeable antioxidant Trolox to examine the role of sROS in mitochondrial morphology, oxidative phosphorylation (OXPHOS), and cytosolic calcium (Ca2+) handling in healthy human skin fibroblasts. Results and Innovation: Trolox treatment reduced the levels of 5-(and-6)-chloromethyl-2′,7′-dichlorodihydro-fluorescein (CM-H2DCF) oxidizing ROS, lowered cellular lipid peroxidation, and induced a less oxidized mitochondrial thiol redox state. This was paralleled by increased glutathione- and mitofusin-dependent mitochondrial filamentation, increased expression of fully assembled mitochondrial complex I, elevated activity of citrate synthase and OXPHOS enzymes, and a higher cellular O2 consumption. In contrast, Trolox did not alter hydroethidium oxidation, cytosolic thiol redox state, mitochondrial NAD(P)H levels, or mitochondrial membrane potential. Whole genome expression profiling revealed that Trolox did not trigger significant changes in gene expression, suggesting that Trolox acts downstream of this process. Cytosolic Ca2+ transients, induced by the hormone bradykinin, were of a higher amplitude and decayed faster in Trolox-treated cells. These effects were dose-dependently antagonized by hydrogen peroxide. Conclusions: Our findings suggest that Trolox-sensitive sROS are upstream regulators of mitochondrial mitofusin levels, morphology, and function in healthy human skin fibroblasts. This information not only facilitates the interpretation of antioxidant effects in cell models (of oxidative-stress), but also contributes to a better understanding of ROS-related human pathologies, including mitochondrial disorders. Antioxid. Redox Signal. 17, 1657–1669. PMID:22559215

  9. A calcium oxide sorbent process for bulk separation of carbon dioxide

    SciTech Connect

    Harrison, D.P.

    1990-09-01

    This research effort is designed to investigate the technical feasibility of a high-temperature, high-pressure process for the bulk separation of CO{sub 2} from coal-derived gases. The two-year contract was awarded in September 1989. This report describes the research effort and results obtained during the first year of the effort. The overall project consists of 6 tasks, four of which were active during year 01. Tasks 1 and 2 were completed during the year while activity in Tasks 3 and 6 will carry over into year 02. Tasks 4 and 5 will be initiated during year 02. Three primary objectives were met in Task 1. A literature search on the calcination-carbonation reactions of CO{sub 2} with calcium-based sorbents was completed. A high temperature, high pressure (HTHP) electrobalance reactor suitable for studying the calcination and carbonation reactions was constructed. This reactor system is now fully operable and we are routinely collecting kinetics data at temperatures in the range of 550-900{degree}C and pressures of 1 to 15 atm. Samples of nine candidate calcium-based sorbents were acquired and tested. These samples were subjected to reaction screening tests as part of Task 2. As a result of these screening tests, chemically pure calcium carbonate, chemically pure calcium acetate, and the commercial dolomite were selected for more detailed kinetic testing. In Task 3, the HTHP electrobalance reactor is being used to study the calcination-carbonation behavior of the three base sorbents as a function of calcination temperature, carbonation temperature, carbonation pressure, and CO{sub 2} concentration.

  10. Proinflammatory cytokine and nitric oxide production by human macrophages stimulated with Trichomonas vaginalis.

    PubMed

    Han, Ik-Hwan; Goo, Sung Young; Park, Soon-Jung; Hwang, Se-Jin; Kim, Yong-Seok; Yang, Michael Sungwoo; Ahn, Myoung-Hee; Ryu, Jae-Sook

    2009-09-01

    Trichomonas vaginalis commonly causes vaginitis and perhaps cervicitis in women and urethritis in men and women. Macrophages are important immune cells in response to T. vaginalis infection. In this study, we investigated whether human macrophages could be involved in inflammation induced by T. vaginalis. Human monocyte-derived macrophages (HMDM) were co-cultured with T. vaginalis. Live, opsonized-live trichomonads, and T. vaginalis lysates increased proinflammatory cytokines, such as TNF-alpha, IL-1beta, and IL-6 by HMDM. The involvement of nuclear factor (NF)-kappaB signaling pathway in cytokine production induced by T. vaginalis was confirmed by phosphorylation and nuclear translocation of p65 NF-kappaB. In addition, stimulation with live T. vaginalis induced marked augmentation of nitric oxide (NO) production and expression of inducible NO synthase (iNOS) levels in HMDM. However, trichomonad-induced NF-kappaB activation and TNF-alpha production in macrophages were significantly inhibited by inhibition of iNOS levels with L-NMMA (NO synthase inhibitor). Moreover, pretreatment with NF-kappaB inhibitors (PDTC or Bay11-7082) caused human macrophages to produce less TNF-alpha. These results suggest that T. vaginalis stimulates human macrophages to produce proinflammatory cytokines, such as IL-1, IL-6, and TNF-alpha, and NO. In particular, we showed that T. vaginalis induced TNF-alpha production in macrophages through NO-dependent activation of NF-kappaB, which might be closely involved in inflammation caused by T. vaginalis. PMID:19724692

  11. Hyposensitivity to nerve stimulation in portal hypertensive rats: role of nitric oxide.

    PubMed

    Sieber, C C; Sumanovski, L T; Moll-Kaufmann, C; Stalder, G A

    1997-11-01

    Portal hypertension goes along with vascular hyporeactivity, partly mediated by nitric oxide (NO). Interactions between the adrenergic nervous system and NO in portal hypertension are undetermined. We tested (1) whether superior mesenteric arterial beds of portal hypertensive rats have an altered sensitivity to periarterial nerve stimulation (PNS) and (2) the role of NO in modulating nerve-stimulated responses. Vasopressor responses to PNS (Hz, 2-32) were similar in preparations of partial portal vein-ligated (PVL, n = 12) and control (CON, n = 12) rats (60.0 +/- 6.7 and 47.8 +/- 6.1 CmH2O respectively) for 24 Hz (NS), but sensitivity of vessels of portal hypertensive animals displayed a significant rightward shift [Hz needed for 50% of maximal response (HZ50) being 15.5 +/- 0.4 and 12.9 +/- 0.6 for PVL and CON respectively, P < 0.001]. NO formation inhibition by N omega-nitro-L-arginine (10(-4) mol L-1) significantly increased responses to PNS (P < 0.05), the absolute values for 24 Hz being 101.4 +/- 11.7 cmH2O for PVL (n = 8) and 86.4 +/- 11.4 cmH2O for CON (n = 7) (NS). NO formation inhibition reversed the hyposensitivity in preparations of PVL, Hz50 being 13.9 +/- 0.5 and 13.2 +/- 0.2 for PVL and CON respectively (NS). Adrenergic receptor antagonism with prazosin (10(-7) mol L-1) and yohimbine (10(-6) mol L-1) inhibited PNS-mediated vasopressor reactivity (n = 6 per group, P < 0.001), confirming the nervous origin of vasoconstrictor responses. It is concluded that (1) portal hypertension goes along with a significant hyposensitivity to PNS and (2) this hyposensitivity is reversed by NO-formation inhibition PMID:9395785

  12. Hyposensitivity to nerve stimulation in portal hypertensive rats: role of nitric oxide.

    PubMed

    Sieber, C C; Sumanovski, L T; Moll-Kaufmann, C; Stalder, G A

    1997-11-01

    Portal hypertension goes along with vascular hyporeactivity, partly mediated by nitric oxide (NO). Interactions between the adrenergic nervous system and NO in portal hypertension are undetermined. We tested (1) whether superior mesenteric arterial beds of portal hypertensive rats have an altered sensitivity to periarterial nerve stimulation (PNS) and (2) the role of NO in modulating nerve-stimulated responses. Vasopressor responses to PNS (Hz, 2-32) were similar in preparations of partial portal vein-ligated (PVL, n = 12) and control (CON, n = 12) rats (60.0 +/- 6.7 and 47.8 +/- 6.1 CmH2O respectively) for 24 Hz (NS), but sensitivity of vessels of portal hypertensive animals displayed a significant rightward shift [Hz needed for 50% of maximal response (HZ50) being 15.5 +/- 0.4 and 12.9 +/- 0.6 for PVL and CON respectively, P < 0.001]. NO formation inhibition by N omega-nitro-L-arginine (10(-4) mol L-1) significantly increased responses to PNS (P < 0.05), the absolute values for 24 Hz being 101.4 +/- 11.7 cmH2O for PVL (n = 8) and 86.4 +/- 11.4 cmH2O for CON (n = 7) (NS). NO formation inhibition reversed the hyposensitivity in preparations of PVL, Hz50 being 13.9 +/- 0.5 and 13.2 +/- 0.2 for PVL and CON respectively (NS). Adrenergic receptor antagonism with prazosin (10(-7) mol L-1) and yohimbine (10(-6) mol L-1) inhibited PNS-mediated vasopressor reactivity (n = 6 per group, P < 0.001), confirming the nervous origin of vasoconstrictor responses. It is concluded that (1) portal hypertension goes along with a significant hyposensitivity to PNS and (2) this hyposensitivity is reversed by NO-formation inhibition

  13. An uncertain role for Cu(II) in stimulating Mn(II) oxidation by Leptothrix discophora SS-1.

    PubMed

    El Gheriany, Iman A; Bocioaga, Daniela; Hay, Anthony G; Ghiorse, William C; Shuler, Michael L; Lion, Leonard W

    2011-02-01

    In an effort to improve understanding of the role of Cu(II) in bacterial Mn(II) oxidation, a model Mn(II)-oxidizing bacterium, Leptothrix discophora SS-1, was grown in presence of toxic and non-toxic concentrations of Cu(II), Cd(II) and Mn(II). Mn(II)-oxidizing activity increased by 40% when cells were grown in the presence of 0.05 microM of Cu(II) and increased twofold at 0.18 microM Cu(II). Toxic levels of Cd(II) did not stimulate Mn(II) oxidizing activity, indicating that Mn(II) oxidation is not a response to metal toxicity. Stimulation by Cu(II) confirms the specific role of Cu(II) in Mn(II) oxidation. Comparison of transcript levels of the multicopper oxidase mofA gene in the presence and absence of added Cu(II) do not indicate a statistically significant change in mofA transcript levels in cultures supplemented with Cu(II). Thus, the exact role of Cu(II) in Mn(II) oxidation and its affect on mofA gene expression remain uncertain. PMID:21063867

  14. The calcium-stimulated lipid A 3-O deacylase from Rhizobium etli is not essential for plant nodulation.

    PubMed

    Sohlenkamp, Christian; Raetz, Christian R H; Ingram, Brian O

    2013-07-01

    The lipid A component of lipopolysaccharide from the nitrogen-fixing plant endosymbiont, Rhizobium etli, is structurally very different from that found in most enteric bacteria. The lipid A from free-living R. etli is structurally heterogeneous and exists as a mixture of species which are either pentaacylated or tetraacylated. In contrast, the lipid A from R. etli bacteroids is reported to consist exclusively of tetraacylated lipid A species. The tetraacylated lipid A species in both cases lack a beta-hydroxymyristoyl chain at the 3-position of lipid A. Here, we show that the lipid A modification enzyme responsible for 3-O deacylation in R. etli is a homolog of the PagL protein originally described in Salmonella enterica sv. typhimurium. In contrast to the PagL proteins described from other species, R. etli PagL displays a calcium dependency. To determine the importance of the lipid A modification catalyzed by PagL, we isolated and characterized a R. etli mutant deficient in the pagL gene. Mass spectrometric analysis confirmed that the mutant strain was exclusively tetraacylated and radiochemical analysis revealed that 3-O deacylase activity was absent in membranes prepared from the mutant. The R. etli mutant was not impaired in its ability to form nitrogen-fixing nodules on Phaseolus vulgaris but it displayed slower nodulation kinetics relative to the wild-type strain. The lipid A modification catalyzed by R. etli PagL, therefore, is not required for nodulation but may play other roles such as protecting bacterial endosymbionts from plant immune responses during infection. PMID:24046865

  15. The calcium-stimulated lipid A 3-O deacylase from Rhizobium etli is not essential for plant nodulation.

    PubMed

    Sohlenkamp, Christian; Raetz, Christian R H; Ingram, Brian O

    2012-07-01

    The lipid A component of lipopolysaccharide from the nitrogen-fixing plant endosymbiont, Rhizobium etli, is structurally very different from that found in most enteric bacteria. The lipid A from free-living R. etli is structurally heterogeneous and exists as a mixture of species which are either pentaacylated or tetraacylated. In contrast, the lipid A from R. etli bacteroids is reported to consist exclusively of tetraacylated lipid A species. The tetraacylated lipid A species in both cases lack a β-hydroxymyristoyl chain at the 3-position of lipid A. Here, we show that the lipid A modification enzyme responsible for 3-O deacylation in R. etli is a homolog of the PagL protein originally described in Salmonella enterica sv. typhimurium. In contrast to the PagL proteins described from other species, R. etli PagL displays a calcium dependency. To determine the importance of the lipid A modification catalyzed by PagL, we isolated and characterized a R. etli mutant deficient in the pagL gene. Mass spectrometric analysis confirmed that the mutant strain was exclusively tetraacylated and radiochemical analysis revealed that 3-O deacylase activity was absent in membranes prepared from the mutant. The R. etli mutant was not impaired in its ability to form nitrogen-fixing nodules on Phaseolus vulgaris but it displayed slower nodulation kinetics relative to the wild-type strain. The lipid A modification catalyzed by R. etli PagL, therefore, is not required for nodulation but may play other roles such as protecting bacterial endosymbionts from plant immune responses during infection. PMID:23583844

  16. Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation

    NASA Astrophysics Data System (ADS)

    He, Fengping; Xu, Xin; Yuan, Shuguo; Tan, Liangqiu; Gao, Lingjun; Ma, Shaochun; Zhang, Shebin; Ma, Zhanzhong; Jiang, Wei; Liu, Fenglian; Chen, Baofeng; Zhang, Beibei; Pang, Jungang; Huang, Xiuyan; Weng, Jiaqiang

    2016-08-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia causing high morbidity and mortality. While changing of the cellular calcium homeostasis plays a critical role in AF, the L-type calcium channel α1c protein has suggested as an important regulator of reentrant spiral dynamics and is a major component of AF-related electrical remodeling. Our computational modeling predicted that miRNA-223 may regulate the CACNA1C gene which encodes the cardiac L-type calcium channel α1c subunit. We found that oxidized low-density lipoprotein (ox-LDL) cholesterol significantly up-regulates both the expression of miRNA-223 and L-type calcium channel protein. In contrast, knockdown of miRNA-223 reduced L-type calcium channel protein expression, while genetic knockdown of endogenous miRNA-223 dampened AF vulnerability. Transfection of miRNA-223 by adenovirus-mediated expression enhanced L-type calcium currents and promoted AF in mice while co-injection of a CACNA1C-specific miR-mimic counteracted the effect. Taken together, ox-LDL, as a known factor in AF-associated remodeling, positively regulates miRNA-223 transcription and L-type calcium channel protein expression. Our results implicate a new molecular mechanism for AF in which miRNA-223 can be used as an biomarker of AF rheumatic heart disease.

  17. Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation.

    PubMed

    He, Fengping; Xu, Xin; Yuan, Shuguo; Tan, Liangqiu; Gao, Lingjun; Ma, Shaochun; Zhang, Shebin; Ma, Zhanzhong; Jiang, Wei; Liu, Fenglian; Chen, Baofeng; Zhang, Beibei; Pang, Jungang; Huang, Xiuyan; Weng, Jiaqiang

    2016-01-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia causing high morbidity and mortality. While changing of the cellular calcium homeostasis plays a critical role in AF, the L-type calcium channel α1c protein has suggested as an important regulator of reentrant spiral dynamics and is a major component of AF-related electrical remodeling. Our computational modeling predicted that miRNA-223 may regulate the CACNA1C gene which encodes the cardiac L-type calcium channel α1c subunit. We found that oxidized low-density lipoprotein (ox-LDL) cholesterol significantly up-regulates both the expression of miRNA-223 and L-type calcium channel protein. In contrast, knockdown of miRNA-223 reduced L-type calcium channel protein expression, while genetic knockdown of endogenous miRNA-223 dampened AF vulnerability. Transfection of miRNA-223 by adenovirus-mediated expression enhanced L-type calcium currents and promoted AF in mice while co-injection of a CACNA1C-specific miR-mimic counteracted the effect. Taken together, ox-LDL, as a known factor in AF-associated remodeling, positively regulates miRNA-223 transcription and L-type calcium channel protein expression. Our results implicate a new molecular mechanism for AF in which miRNA-223 can be used as an biomarker of AF rheumatic heart disease. PMID:27488468

  18. Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation.

    PubMed

    He, Fengping; Xu, Xin; Yuan, Shuguo; Tan, Liangqiu; Gao, Lingjun; Ma, Shaochun; Zhang, Shebin; Ma, Zhanzhong; Jiang, Wei; Liu, Fenglian; Chen, Baofeng; Zhang, Beibei; Pang, Jungang; Huang, Xiuyan; Weng, Jiaqiang

    2016-08-04

    Atrial fibrillation (AF) is the most common sustained arrhythmia causing high morbidity and mortality. While changing of the cellular calcium homeostasis plays a critical role in AF, the L-type calcium channel α1c protein has suggested as an important regulator of reentrant spiral dynamics and is a major component of AF-related electrical remodeling. Our computational modeling predicted that miRNA-223 may regulate the CACNA1C gene which encodes the cardiac L-type calcium channel α1c subunit. We found that oxidized low-density lipoprotein (ox-LDL) cholesterol significantly up-regulates both the expression of miRNA-223 and L-type calcium channel protein. In contrast, knockdown of miRNA-223 reduced L-type calcium channel protein expression, while genetic knockdown of endogenous miRNA-223 dampened AF vulnerability. Transfection of miRNA-223 by adenovirus-mediated expression enhanced L-type calcium currents and promoted AF in mice while co-injection of a CACNA1C-specific miR-mimic counteracted the effect. Taken together, ox-LDL, as a known factor in AF-associated remodeling, positively regulates miRNA-223 transcription and L-type calcium channel protein expression. Our results implicate a new molecular mechanism for AF in which miRNA-223 can be used as an biomarker of AF rheumatic heart disease.

  19. Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation

    PubMed Central

    He, Fengping; Xu, Xin; Yuan, Shuguo; Tan, Liangqiu; Gao, Lingjun; Ma, Shaochun; Zhang, Shebin; Ma, Zhanzhong; Jiang, Wei; Liu, Fenglian; Chen, Baofeng; Zhang, Beibei; Pang, Jungang; Huang, Xiuyan; Weng, Jiaqiang

    2016-01-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia causing high morbidity and mortality. While changing of the cellular calcium homeostasis plays a critical role in AF, the L-type calcium channel α1c protein has suggested as an important regulator of reentrant spiral dynamics and is a major component of AF-related electrical remodeling. Our computational modeling predicted that miRNA-223 may regulate the CACNA1C gene which encodes the cardiac L-type calcium channel α1c subunit. We found that oxidized low-density lipoprotein (ox-LDL) cholesterol significantly up-regulates both the expression of miRNA-223 and L-type calcium channel protein. In contrast, knockdown of miRNA-223 reduced L-type calcium channel protein expression, while genetic knockdown of endogenous miRNA-223 dampened AF vulnerability. Transfection of miRNA-223 by adenovirus-mediated expression enhanced L-type calcium currents and promoted AF in mice while co-injection of a CACNA1C-specific miR-mimic counteracted the effect. Taken together, ox-LDL, as a known factor in AF-associated remodeling, positively regulates miRNA-223 transcription and L-type calcium channel protein expression. Our results implicate a new molecular mechanism for AF in which miRNA-223 can be used as an biomarker of AF rheumatic heart disease. PMID:27488468

  20. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate.

    PubMed

    Pilo, Raphael; Harel, Noga; Nissan, Joseph; Levartovsky, Shifra

    2016-01-01

    The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP) crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC) or Self Adhesive Resin Cement (SARC)). Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa) were significantly higher than those for SARC (2.28 ± 0.58 MPa). The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns. PMID:27023532

  1. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate.

    PubMed

    Pilo, Raphael; Harel, Noga; Nissan, Joseph; Levartovsky, Shifra

    2016-03-25

    The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP) crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC) or Self Adhesive Resin Cement (SARC)). Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa) were significantly higher than those for SARC (2.28 ± 0.58 MPa). The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns.

  2. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate

    PubMed Central

    Pilo, Raphael; Harel, Noga; Nissan, Joseph; Levartovsky, Shifra

    2016-01-01

    The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP) crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC) or Self Adhesive Resin Cement (SARC)). Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa) were significantly higher than those for SARC (2.28 ± 0.58 MPa). The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns. PMID:27023532

  3. Role of calcium oxide in sludge granulation and methanogenesis for the treatment of palm oil mill effluent using UASB reactor.

    PubMed

    Ahmad, Anwar; Ghufran, Rumana; Abd Wahid, Zularisam

    2011-12-30

    The granulation process in palm oil mill effluent using calcium oxide-cement kiln dust (CaO-CKD) provides an attractive and cost effective treatment option. In this study the efficiency of CaO-CKD at doses of 1.5-20 g/l was tested in batch experiments and found that 10 g of CaO/l caused the greatest degradation of VFA, butyrate and acetate. An upflow anaerobic sludge blanket (UASB) reactor was operated continuously at 35°C for 150 days to investigate the effect of CaO-CKD on sludge granulation and methanogenesis during start-up. The treatment of POME emphasized the influence of varying organic loading rates (OLR). Up to 94.9% of COD was removed when the reactor was fed with the 15.5-65.5 g-CODg/l at an OLR of 4.5-12.5 kg-COD/m(3)d, suggesting the feasibility of using CaO in an UASB process to treat POME. The ratio of volatile solids/total solids (VS/TS) and volatile fatty acids in the anaerobic sludge in the UASB reactor decreased significantly after long-term operation due to the precipitation of calcium carbonate in the granules. Granulation and methanogenesis decreased with an increase in the influent CaO-CKD concentration. PMID:22047724

  4. Calcium oxide derived from waste shells of mussel, cockle, and scallop as the heterogeneous catalyst for biodiesel production.

    PubMed

    Buasri, Achanai; Chaiyut, Nattawut; Loryuenyong, Vorrada; Worawanitchaphong, Phatsakon; Trongyong, Sarinthip

    2013-01-01

    The waste shell was utilized as a bioresource of calcium oxide (CaO) in catalyzing a transesterification to produce biodiesel (methyl ester). The economic and environmen-friendly catalysts were prepared by a calcination method at 700-1,000°C for 4 h. The heterogeneous catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET) method. The effects of reaction variables such as reaction time, reaction temperature, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the CaO catalysts derived from waste shell showed good reusability and had high potential to be used as biodiesel production catalysts in transesterification of palm oil with methanol.

  5. Overcoming the problem of loss-in-capacity of calcium oxide in CO{sub 2} capture

    SciTech Connect

    Bo Feng; Wenqiang Liu; Xiang Li; Hui An

    2006-12-15

    Calcium oxide has been identified to be one of the best candidates for CO{sub 2} capture in zero-emission power-generation systems. However, it suffers a well-known problem of loss-in-capacity (i.e., its capacity of CO{sub 2} capture decreases after it undergoes cycles of carbonation/decarbonation). This problem is a potential obstacle to the adoption of the new technologies. This paper proposes a method of fabricating a CaO-based adsorbent without the problem of loss-in-capacity. An adsorbent was fabricated using the method and tested on a thermogravimetric analyzer. It was shown that the sorbent attained a utilization efficiency of more than 90% after 9 cycles of carbonation/decarbonation. 19 refs., 3 figs.

  6. Calcium oxide derived from waste shells of mussel, cockle, and scallop as the heterogeneous catalyst for biodiesel production.

    PubMed

    Buasri, Achanai; Chaiyut, Nattawut; Loryuenyong, Vorrada; Worawanitchaphong, Phatsakon; Trongyong, Sarinthip

    2013-01-01

    The waste shell was utilized as a bioresource of calcium oxide (CaO) in catalyzing a transesterification to produce biodiesel (methyl ester). The economic and environmen-friendly catalysts were prepared by a calcination method at 700-1,000°C for 4 h. The heterogeneous catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET) method. The effects of reaction variables such as reaction time, reaction temperature, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the CaO catalysts derived from waste shell showed good reusability and had high potential to be used as biodiesel production catalysts in transesterification of palm oil with methanol. PMID:24453854

  7. Expression of the calcium-independent cytokine-inducible (iNOS) isoform of nitric oxide synthase in rat placenta.

    PubMed Central

    Casado, M; D-iaz-Guerra, M J; Rodrigo, J; Fernández, A P; Boscá, L; Martín-Sanz, P

    1997-01-01

    The presence of the calcium-independent cytokine-inducible nitric oxide synthase (iNOS) has been investigated in rat placenta from day 19 of gestation till delivery. iNOS has been detected at the mRNA, enzyme activity and protein levels in complete placenta. Immunocytochemical detection of iNOS was heterogeneously distributed in control placenta. Intraperitoneal injection of pregnant rats at 21 days of gestation with lipopolysaccharide (LPS) increased the iNOS immunoreactivity in the decidua basalis of the placenta, and, when the mRNA levels and enzyme activity were measured in total tissue, a moderate increase (approx. 160%) was observed. A constitutive nuclear factor kappaB activity was observed in placenta from both control and LPS-treated animals. These results indicate constitutive expression of iNOS in rat placenta. PMID:9164857

  8. Dry mechanochemical synthesis of hydroxyapatites from dicalcium phosphate dihydrate and calcium oxide: a kinetic study.

    PubMed

    El Briak-BenAbdeslam, Hassane; Mochales, Carolina; Ginebra, Maria Pau; Nurit, Josiane; Planell, Josep A; Boudeville, Philippe

    2003-12-01

    Calcium phosphate ceramics have been used successfully as synthetic bone substitutes in orthopedics, dentistry, and maxillofacial surgery. One way of preparing these ceramics is the sintering of a calcium-deficient hydroxyapatite (CDHA), which can be obtained in different ways. Mechanochemistry is one possible means of synthesizing CDHA, with an expected molar calcium-to-phosphate (Ca/P) ratio +/- 0.005. The grinding can be carried out under dry or wet conditions. To optimize the experimental conditions of CDHA preparation by dry mechanosynthesis and for a better understanding of the DCPD/CaO mechanochemical reaction, we performed a kinetic study in which some of the experimental parameters were varied. Carried out with two different vertical rotating ball mills, this kinetic study showed that (1) experiments are reproducible and give as a final product a hydroxyapatite powder, formed of nano-sized crystals of around 20 nm, with a controlled Ca/P ratio; (2) the time for complete disappearance of DCPD and the time for complete reaction are in direct proportion to the mass of the ground powder; but (3) the time for complete disappearance of DCPD is independent of the Ca/P ratio while the time for complete reaction increases exponentially with the Ca/P ratio; and (4) the time for complete disappearance of DCPD corresponds to the time for complete reaction solely for Ca/P = 1.5. These observations suggest a reaction mechanism in two well differentiated stages: (First stage) CaO reacts with DCPD to give first an amorphous calcium phosphate (ACP) with a low Ca/P ratio that transforms into CDHA when its Ca/P ratio reaches 1.5. At the same time, CaO is hydrated into Ca(OH)(2) by the water produced by the reaction. (Second stage) If the Ca/P > 1.5 in the initial mixture, the excess Ca(OH)(2) is added to CDHA 1.5 by reacting with the HPO(4) group of CDHA until its Ca/P ratio reaches the expected value. The slower the reaction, the higher the Ca/P in the initial mixture.

  9. Dry mechanochemical synthesis of hydroxyapatites from dicalcium phosphate dihydrate and calcium oxide: a kinetic study.

    PubMed

    El Briak-BenAbdeslam, Hassane; Mochales, Carolina; Ginebra, Maria Pau; Nurit, Josiane; Planell, Josep A; Boudeville, Philippe

    2003-12-01

    Calcium phosphate ceramics have been used successfully as synthetic bone substitutes in orthopedics, dentistry, and maxillofacial surgery. One way of preparing these ceramics is the sintering of a calcium-deficient hydroxyapatite (CDHA), which can be obtained in different ways. Mechanochemistry is one possible means of synthesizing CDHA, with an expected molar calcium-to-phosphate (Ca/P) ratio +/- 0.005. The grinding can be carried out under dry or wet conditions. To optimize the experimental conditions of CDHA preparation by dry mechanosynthesis and for a better understanding of the DCPD/CaO mechanochemical reaction, we performed a kinetic study in which some of the experimental parameters were varied. Carried out with two different vertical rotating ball mills, this kinetic study showed that (1) experiments are reproducible and give as a final product a hydroxyapatite powder, formed of nano-sized crystals of around 20 nm, with a controlled Ca/P ratio; (2) the time for complete disappearance of DCPD and the time for complete reaction are in direct proportion to the mass of the ground powder; but (3) the time for complete disappearance of DCPD is independent of the Ca/P ratio while the time for complete reaction increases exponentially with the Ca/P ratio; and (4) the time for complete disappearance of DCPD corresponds to the time for complete reaction solely for Ca/P = 1.5. These observations suggest a reaction mechanism in two well differentiated stages: (First stage) CaO reacts with DCPD to give first an amorphous calcium phosphate (ACP) with a low Ca/P ratio that transforms into CDHA when its Ca/P ratio reaches 1.5. At the same time, CaO is hydrated into Ca(OH)(2) by the water produced by the reaction. (Second stage) If the Ca/P > 1.5 in the initial mixture, the excess Ca(OH)(2) is added to CDHA 1.5 by reacting with the HPO(4) group of CDHA until its Ca/P ratio reaches the expected value. The slower the reaction, the higher the Ca/P in the initial mixture. PMID

  10. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    SciTech Connect

    Lee, Ha Young; Kim, Sang Doo; Baek, Suk-Hwan; Choi, Joon Hyuk; Cho, Kyung-Hyun; Zabel, Brian A.; Bae, Yoe-Sik

    2013-03-29

    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  11. Fluid flow stimulates rapid and continuous release of nitric oxide in osteoblasts

    NASA Technical Reports Server (NTRS)

    Johnson, D. L.; McAllister, T. N.; Frangos, J. A.

    1996-01-01

    Interstitial fluid flow may mediate skeletal remodeling in response to mechanical loading. Because nitric oxide (NO) has been shown to be an osteoblast mitogen and inhibitor of osteoclastic resorption, we investigated and characterized the role of fluid shear on the release of NO in osteoblasts. Rat calvarial cells in a stationary culture produced undetectable levels of NO. Fluid shear stress (6 dyn/cm2) rapidly increased NO release rate to 9.8 nmol.h-1.mg protein-1 and sustained this production for 12 h of exposure to flow. Cytokine treatment also induced NO synthesis after a 12-h lag phase of zero production, followed by a production rate of 0.6 nmol.h-1.mg protein-1. Flow-induced NO production was blocked by the NO synthase (NOS) inhibitor NG-amino-L-arginine, but not by dexamethasone, which suggests that the flow stimulated a constitutive NOS isoform. This is the first time that a functional constitutively present NOS isoform has been identified in osteoblasts. Moreover, fluid flow represents the most potent stimulus of NO release in osteoblasts reported to date. Fluid flow-induced NO production may therefore play a primary role in bone maintenance and remodeling.

  12. Investigation of the radiation stimulated oxidation of sulfite by molecular oxygen in aqueous solutions

    SciTech Connect

    Muratbekov, M.B.; Koroleva, G.Y.

    1986-09-01

    The principles of the radiation-stimulated oxidation of sulfite by molecular oxygen in the range of pH 11.0-14.6 were investigated. It was established that with increasing sulfite concentration, the kinetic order of the reaction with respect to sulfite falls from 1 to 0, and with respect to oxygen it increases from 0 to 1. This is explained by the fact that at low sulfite concentrations the rate-determining step of the process is the reaction SO/sub 5//sup -/ (HSO/sub 5/) + SO/sub 3//sup 2 -/ ..-->.. SO/sub 4//sup -/ (HSO/sub 4/) + SO/sub 4//sup 2 -/, while at high concentrations it is the reaction SO/sub 3/ + O/sub 2/ ..-->.. SO/sub 5//sup -/. The influence of the pH is explained on the assumption of the existence of two forms of the peroxomonosulfate radical, the more reactive of which is the acid. A number of ratios of reaction rate constants were determined.

  13. Involvement of purinergic signaling on nitric oxide production by neutrophils stimulated with Trichomonas vaginalis.

    PubMed

    Frasson, Amanda Piccoli; De Carli, Geraldo Attilio; Bonan, Carla Denise; Tasca, Tiana

    2012-03-01

    Trichomonas vaginalis is a parasite from the human urogenital tract that causes trichomonosis, the most prevalent non-viral sexually transmitted disease. The neutrophil infiltration has been considered to be primarily responsible for cytological changes observed at infection site, and the chemoattractants can play an important role in this leukocytic recruitment. Nitric oxide (NO) is one of the most widespread mediator compounds, and it is implicated in modulation of immunological mechanisms. Extracellular nucleotides and nucleosides are signaling molecules involved in several processes, including immune responses and control of leukocyte trafficking. Ectonucleoside triphosphate diphosphohydrolase members, ecto-5'-nucleotidase, and adenosine deaminase (ectoADA) have been characterized in T. vaginalis. Herein, we investigated the effects of purinergic system on NO production by neutrophils stimulated with T. vaginalis. The trophozoites were able to induce a high NO synthesis by neutrophils through iNOS pathway. The extracellular nucleotides ATP, ADP, and ATPγS (a non-hydrolyzable ATP analog) showed no significant change in NO secretion. In contrast, adenosine and its degradation product, inosine, promoted a low production of the compound. The immunosuppressive effect of adenosine upon NO release by neutrophils occurred due to adenosine A(2A) receptor activation. The ecto-5'-nucleotidase activity displayed by T. vaginalis was shown to be important in adenosine generation, indicating the efficiency of purinergic cascade. Our data suggest the influence of purinergic signaling, specifically adenosinergic system, on NO production by neutrophils in T. vaginalis infection, contributing to the immunological aspects of disease.

  14. Anthropogenic pollution stimulates oxidative stress in soft tissues of mussel Crenomytilus grayanus (Dunker1853)

    NASA Astrophysics Data System (ADS)

    Belcheva, Nina N.; Zakhartsev, Maxim V.; Dovzhenko, Nadezhda V.; Zhukovskaya, Avianna F.; Kavun, Victor Ya.; Chelomin, Victor P.

    2011-06-01

    The digestive gland and gills of the mussel Crenomytilus grayanus extracted from three locations — (i) sampled from a clean and (ii) polluted site and (iii) transplanted from the nonpolluted to polluted site - were analysed for antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase), total oxyradical scavenging capacity and levels of lipid peroxidation products (malondialdehyde, conjugated dienes and lipofuscin). Perturbation of redox status was found in both digestive gland and gill tissues of mussels living in the polluted area. As the activities of superoxide dismutase and catalase were 1.2-3 times higher, the total oxyradical scavenging capacity was lower by 20-35% and the levels of lipid peroxidation products were 2-7 times higher compared to mussels from the reference site. In transplanted mussels, the lipid peroxidation process in both tissues was significantly stimulated (the level of conjugated dienes was increased 1.7-2.5-fold; malondialdehyde and lipofuscin contents were increased 3.5-5-fold) and the total oxyradical scavenging capacity fell by 50-70%. In addition, the transplantation generally resulted in transient and variable responses of antioxidant enzymes for both tissues. Complex response-behaviour of the antioxidant enzymes strongly points to the necessity of employing a combined approach that takes into account activities of antioxidant enzymes and the total oxyradical scavenging capacity, as well as measurement of oxidative damage (e.g., lipid peroxidation) to evaluate the physiological health of molluscs.

  15. Stimulation by ammonium-based fertilizers of methane oxidation in soil around rice roots.

    PubMed

    Bodelier, P L; Roslev, P; Henckel, T; Frenzel, P

    2000-01-27

    Methane is involved in a number of chemical and physical processes in the Earth's atmosphere, including global warming. Atmospheric methane originates mainly from biogenic sources, such as rice paddies and natural wetlands; the former account for at least 30% of the global annual emission of methane to the atmosphere. As an increase of rice production by 60% is the most appropriate way to sustain the estimated increase of the human population during the next three decades, intensified global fertilizer application will be necessary: but it is known that an increase of the commonly used ammonium-based fertilizers can enhance methane emission from rice agriculture. Approximately 10-30% of the methane produced by methanogens in rice paddies is consumed by methane-oxidizing bacteria associated with the roots of rice; these bacteria are generally thought to be inhibited by ammonium-based fertilizers, as was demonstrated for soils and sediments. In contrast, we show here that the activity and growth of such bacteria in the root zone of rice plants are stimulated after fertilization. Using a combination of radioactive fingerprinting and molecular biology techniques, we identify the bacteria responsible for this effect. We expect that our results will make necessary a re-evaluation of the link between fertilizer use and methane emissions, with effects on global warming studies.

  16. Nitric oxide fumigation stimulates flavonoid and phenolic accumulation and enhances antioxidant activity of mushroom.

    PubMed

    Dong, Jufang; Zhang, Ming; Lu, Li; Sun, Lina; Xu, Maojun

    2012-12-01

    The effects of nitric oxide (NO) on antioxidant activity and contents of phenolics and flavonoids in mushroom Russula griseocarnosa were investigated. Freshly harvested mushrooms were fumigated with 0, 10, 20 and 30μLL(-1) NO at 20°C for 2h and then taken to examine the antioxidant activities using assays of reducing power, chelating effect on ferrous ions, scavenging effect on hydroxyl free radicals, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. The results showed that the antioxidant activities of the mushrooms fumigated with NO were significantly increased when compared to the controls. Moreover, NO fumigation significantly enhanced phenolic and flavonoid contents and stimulated the activities of phenylalanine ammonia-lyase and chalcone synthase. The results indicated that NO fumigation might have potential application for enhancing the bioactive compounds and improving antioxidant activities in the mushrooms. Furthermore, the data suggested that the NO-induced phenolic and flavonoid accumulation was due to the activation of the biosynthetic pathways in the mushrooms.

  17. Glucose deprivation causes oxidative stress and stimulates aggresome formation and autophagy in cultured cardiac myocytes.

    PubMed

    Marambio, Paola; Toro, Barbra; Sanhueza, Carlos; Troncoso, Rodrigo; Parra, Valentina; Verdejo, Hugo; García, Lorena; Quiroga, Clara; Munafo, Daniela; Díaz-Elizondo, Jessica; Bravo, Roberto; González, María-Julieta; Diaz-Araya, Guilermo; Pedrozo, Zully; Chiong, Mario; Colombo, María Isabel; Lavandero, Sergio

    2010-06-01

    Aggresomes are dynamic structures formed when the ubiquitin-proteasome system is overwhelmed with aggregation-prone proteins. In this process, small protein aggregates are actively transported towards the microtubule-organizing center. A functional role for autophagy in the clearance of aggresomes has also been proposed. In the present work we investigated the molecular mechanisms involved on aggresome formation in cultured rat cardiac myocytes exposed to glucose deprivation. Confocal microscopy showed that small aggregates of polyubiquitinated proteins were formed in cells exposed to glucose deprivation for 6 h. However, at longer times (18 h), aggregates formed large perinuclear inclusions (aggresomes) which colocalized with gamma-tubulin (a microtubule-organizing center marker) and Hsp70. The microtubule disrupting agent vinblastine prevented the formation of these inclusions. Both small aggregates and aggresomes colocalized with autophagy markers such as GFP-LC3 and Rab24. Glucose deprivation stimulates reactive oxygen species (ROS) production and decreases intracellular glutathione levels. ROS inhibition by N-acetylcysteine or by the adenoviral overexpression of catalase or superoxide dismutase disrupted aggresome formation and autophagy induced by glucose deprivation. In conclusion, glucose deprivation induces oxidative stress which is associated with aggresome formation and activation of autophagy in cultured cardiac myocytes. PMID:20176105

  18. Neuronal nitric oxide synthase is phosphorylated in response to insulin stimulation in skeletal muscle

    PubMed Central

    Hinchee-Rodriguez, Kathryn; Garg, Neha; Venkatakrishnan, Priya; Roman, Madeline G.; Adamo, Martin L.; Masters, Bettie Sue; Roman, Linda J.

    2013-01-01

    Type 2 Diabetes (T2DM) is the seventh leading cause of death in the United States, and is quickly becoming a global pandemic. T2DM results from reduced insulin sensitivity coupled with a relative failure of insulin secretion. Reduced insulin sensitivity has been associated with reduced nitric oxide synthase (NOS) activity and impaired glucose uptake in T2DM skeletal muscle. Upon insulin stimulation, NO synthesis increases in normal adult skeletal muscle, whereas no such increase is observed in T2DM adults. Endothelial NOS is activated by phosphorylation in the C-terminal tail in response to insulin. Neuronal NOS (nNOS), the primary NOS isoform in skeletal muscle, contains a homologous phosphorylation site, raising the possibility that nNOS, too, may undergo an activating phosphorylation event upon insulin treatment. Yet it remains unknown if or how nNOS is regulated by insulin in skeletal muscle. Data shown herein indicate that nNOS is phosphorylated in response to insulin in skeletal muscle and that this phosphorylation event occurs rapidly in C2C12 myotubes, resulting in increased NO production. In vivo phosphorylation of nNOS was also observed in response to insulin in mouse skeletal muscle. These results indicate, for the first time, that nNOS is phosphorylated in skeletal muscle in response to insulin and in association with increased NO production. PMID:23680665

  19. Neuronal nitric oxide synthase is phosphorylated in response to insulin stimulation in skeletal muscle.

    PubMed

    Hinchee-Rodriguez, Kathryn; Garg, Neha; Venkatakrishnan, Priya; Roman, Madeline G; Adamo, Martin L; Masters, Bettie Sue; Roman, Linda J

    2013-06-01

    Type 2 Diabetes (T2DM) is the seventh leading cause of death in the United States, and is quickly becoming a global pandemic. T2DM results from reduced insulin sensitivity coupled with a relative failure of insulin secretion. Reduced insulin sensitivity has been associated with reduced nitric oxide synthase (NOS) activity and impaired glucose uptake in T2DM skeletal muscle. Upon insulin stimulation, NO synthesis increases in normal adult skeletal muscle, whereas no such increase is observed in T2DM adults. Endothelial NOS is activated by phosphorylation in the C-terminal tail in response to insulin. Neuronal NOS (nNOS), the primary NOS isoform in skeletal muscle, contains a homologous phosphorylation site, raising the possibility that nNOS, too, may undergo an activating phosphorylation event upon insulin treatment. Yet it remains unknown if or how nNOS is regulated by insulin in skeletal muscle. Data shown herein indicate that nNOS is phosphorylated in response to insulin in skeletal muscle and that this phosphorylation event occurs rapidly in C2C12 myotubes, resulting in increased NO production. In vivo phosphorylation of nNOS was also observed in response to insulin in mouse skeletal muscle. These results indicate, for the first time, that nNOS is phosphorylated in skeletal muscle in response to insulin and in association with increased NO production. PMID:23680665

  20. Inducible Nitric Oxide Inhibitors Block NMDA Antagonist-Stimulated Motoric Behaviors and Medial Prefrontal Cortical Glutamate Efflux

    PubMed Central

    Bergstrom, Hadley C.; Darvesh, Altaf S.; Berger, S. P.

    2015-01-01

    Nitric oxide (NO) plays a critical role in the motoric and glutamate releasing action of N-methyl-D-aspartate (NMDA)-antagonist stimulants. Earlier studies utilized neuronal nitric oxide synthase inhibitors (nNOS) for studying the neurobehavioral effects of non-competitive NMDA-antagonist stimulants such as dizocilpine (MK-801) and phencyclidine (PCP). This study explores the role of the inducible nitric oxide synthase inhibitors (iNOS) aminoguanidine (AG) and (-)-epigallocatechin-3-gallate (EGCG) in NMDA-antagonist induced motoric behavior and prefrontal cortical glutamate efflux. Adult male rats were administered a dose range of AG, EGCG, or vehicle prior to receiving NMDA antagonists MK-801, PCP, or a conventional psychostimulant (cocaine) and tested for motoric behavior in an open arena. Glutamate in the medial prefrontal cortex (mPFC) was measured using in vivo microdialysis after a combination of AG or EGCG prior to MK-801. Acute administration of AG or EGCG dose-dependently attenuated the locomotor and ataxic properties of MK-801 and PCP. Both AG and EGCG were unable to block the motoric effects of cocaine, indicating the acute pharmacologic action of AG and EGCG is specific to NMDA antagonism and not generalizable to all stimulant class drugs. AG and EGCG normalized MK-801-stimulated mPFC glutamate efflux. These data demonstrate that AG and EGCG attenuates NMDA antagonist-stimulated motoric behavior and cortical glutamate efflux. Our results suggest that EGCG-like polyphenol nutraceuticals (contained in “green tea” and chocolate) may be clinically useful in protecting against the adverse behavioral dissociative and cortical glutamate stimulating effects of NMDA antagonists. Medications that interfere with NMDA antagonists such as MK-801 and PCP have been proposed as treatments for schizophrenia. PMID:26696891

  1. Inducible Nitric Oxide Inhibitors Block NMDA Antagonist-Stimulated Motoric Behaviors and Medial Prefrontal Cortical Glutamate Efflux.

    PubMed

    Bergstrom, Hadley C; Darvesh, Altaf S; Berger, S P

    2015-01-01

    Nitric oxide (NO) plays a critical role in the motoric and glutamate releasing action of N-methyl-D-aspartate (NMDA)-antagonist stimulants. Earlier studies utilized neuronal nitric oxide synthase inhibitors (nNOS) for studying the neurobehavioral effects of non-competitive NMDA-antagonist stimulants such as dizocilpine (MK-801) and phencyclidine (PCP). This study explores the role of the inducible nitric oxide synthase inhibitors (iNOS) aminoguanidine (AG) and (-)-epigallocatechin-3-gallate (EGCG) in NMDA-antagonist induced motoric behavior and prefrontal cortical glutamate efflux. Adult male rats were administered a dose range of AG, EGCG, or vehicle prior to receiving NMDA antagonists MK-801, PCP, or a conventional psychostimulant (cocaine) and tested for motoric behavior in an open arena. Glutamate in the medial prefrontal cortex (mPFC) was measured using in vivo microdialysis after a combination of AG or EGCG prior to MK-801. Acute administration of AG or EGCG dose-dependently attenuated the locomotor and ataxic properties of MK-801 and PCP. Both AG and EGCG were unable to block the motoric effects of cocaine, indicating the acute pharmacologic action of AG and EGCG is specific to NMDA antagonism and not generalizable to all stimulant class drugs. AG and EGCG normalized MK-801-stimulated mPFC glutamate efflux. These data demonstrate that AG and EGCG attenuates NMDA antagonist-stimulated motoric behavior and cortical glutamate efflux. Our results suggest that EGCG-like polyphenol nutraceuticals (contained in "green tea" and chocolate) may be clinically useful in protecting against the adverse behavioral dissociative and cortical glutamate stimulating effects of NMDA antagonists. Medications that interfere with NMDA antagonists such as MK-801 and PCP have been proposed as treatments for schizophrenia.

  2. Mistletoe (Viscum album) infestation in the Scots pine stimulates drought-dependent oxidative damage in summer.

    PubMed

    Mutlu, Salih; Ilhan, Veli; Turkoglu, Halil Ibrahim

    2016-04-01

    This study sought to contribute to the understanding of the detrimental effect of the mistletoe (Viscum albumL.), a hemiparasitic plant, on the mortality of the Scots pine (Pinus sylvestrisL.). Fieldwork was conducted in the town of Kelkit (Gumushane province, Turkey) from April to October in 2013. Pine needles of similar ages were removed from the branches of mistletoe-infested and noninfested Scots pine plants, then transported to the laboratory and used as research materials. The effects of the mistletoe on the Scots pine during infestation were evaluated by determining the levels of water, electrolyte leakage (EL), malondialdehyde (MDA, being a product of lipid peroxidation) and reactive oxygen species (ROS) such as superoxide anion (O2 (-•)), hydrogen peroxide (H2O2) and hydroxyl radical ((•)OH). In addition, the activities of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were measured in the same samples. The highest level of drought stress was found in summer (especially in August) as a result of the lowest water content in the soil and the highest average temperature occurring in these months. The drought stress induced by mistletoe infestation caused a regular decrease in water content, while it increased the levels of EL, MDA and ROS (H2O2, O2 (-•)and(•)OH). The infestation also stimulated the activities of CAT and POX, with the exception of SOD. On the other hand, in August, when the drought conditions were the harshest, the levels of EL and MDA, which are two of the most important indicator parameters for oxidative stress, as well as the levels of H2O2and(•)OH, which are two of the ROS leading to oxidative stress, reached the highest values in both infested and noninfested needles, whereas the O2 (-•)level decreased. For the same period and needles, CAT activity increased, while SOD activity decreased. Peroxidase activity, however, did not exhibit a significant change. Our findings indicate

  3. Mistletoe (Viscum album) infestation in the Scots pine stimulates drought-dependent oxidative damage in summer.

    PubMed

    Mutlu, Salih; Ilhan, Veli; Turkoglu, Halil Ibrahim

    2016-04-01

    This study sought to contribute to the understanding of the detrimental effect of the mistletoe (Viscum albumL.), a hemiparasitic plant, on the mortality of the Scots pine (Pinus sylvestrisL.). Fieldwork was conducted in the town of Kelkit (Gumushane province, Turkey) from April to October in 2013. Pine needles of similar ages were removed from the branches of mistletoe-infested and noninfested Scots pine plants, then transported to the laboratory and used as research materials. The effects of the mistletoe on the Scots pine during infestation were evaluated by determining the levels of water, electrolyte leakage (EL), malondialdehyde (MDA, being a product of lipid peroxidation) and reactive oxygen species (ROS) such as superoxide anion (O2 (-•)), hydrogen peroxide (H2O2) and hydroxyl radical ((•)OH). In addition, the activities of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were measured in the same samples. The highest level of drought stress was found in summer (especially in August) as a result of the lowest water content in the soil and the highest average temperature occurring in these months. The drought stress induced by mistletoe infestation caused a regular decrease in water content, while it increased the levels of EL, MDA and ROS (H2O2, O2 (-•)and(•)OH). The infestation also stimulated the activities of CAT and POX, with the exception of SOD. On the other hand, in August, when the drought conditions were the harshest, the levels of EL and MDA, which are two of the most important indicator parameters for oxidative stress, as well as the levels of H2O2and(•)OH, which are two of the ROS leading to oxidative stress, reached the highest values in both infested and noninfested needles, whereas the O2 (-•)level decreased. For the same period and needles, CAT activity increased, while SOD activity decreased. Peroxidase activity, however, did not exhibit a significant change. Our findings indicate

  4. Role of compost, bentonite and calcium oxide in restricting the effect of soil contamination with petrol and diesel oil on plants.

    PubMed

    Wyszkowski, Mirosław; Ziólkowska, Agnieszka

    2009-02-01

    The studies have been initiated to find a way to use compost, bentonite and calcium oxide in order to reduce the effect of contaminated soil with a small amount of petrol or diesel oil on the yield and nitrogen content in crop plants--spring rape and oats cultivated as the main and aftercrop. Petrol and diesel oil had a toxic effect on the growth of the plants and modified nitrogen content, with the intensity of the effect depending upon their type and dose and on the type of applied substance reducing the effect of oil derivatives. Spring rape (main crop), was more sensitive, and oats (aftercrop) was less so. Petroleum-derived substances reduced the yield of spring rape by a maximum of 73% for petrol and by as much as 99% for diesel oil. Nitrogen content was higher for spring rape than for oats and larger for petrol than for diesel oil. Adding bentonite, calcium oxide or compost to the soil contaminated with oil derivatives usually reduced the negative effect of petrol and diesel oil on plant growth and reduced the protein nitrogen content and increased the total nitrogen content in plants. Bentonite proved to be the most effective, with calcium oxide and compost slightly less so. The most positive results were obtained for spring rape as the main crop. An addition of compost, bentonite and calcium oxide to soil had a stronger modifying effect on nitrogen content in plants on soils contaminated by diesel oil than petrol.

  5. Role of compost, bentonite and calcium oxide in restricting the effect of soil contamination with petrol and diesel oil on plants.

    PubMed

    Wyszkowski, Mirosław; Ziólkowska, Agnieszka

    2009-02-01

    The studies have been initiated to find a way to use compost, bentonite and calcium oxide in order to reduce the effect of contaminated soil with a small amount of petrol or diesel oil on the yield and nitrogen content in crop plants--spring rape and oats cultivated as the main and aftercrop. Petrol and diesel oil had a toxic effect on the growth of the plants and modified nitrogen content, with the intensity of the effect depending upon their type and dose and on the type of applied substance reducing the effect of oil derivatives. Spring rape (main crop), was more sensitive, and oats (aftercrop) was less so. Petroleum-derived substances reduced the yield of spring rape by a maximum of 73% for petrol and by as much as 99% for diesel oil. Nitrogen content was higher for spring rape than for oats and larger for petrol than for diesel oil. Adding bentonite, calcium oxide or compost to the soil contaminated with oil derivatives usually reduced the negative effect of petrol and diesel oil on plant growth and reduced the protein nitrogen content and increased the total nitrogen content in plants. Bentonite proved to be the most effective, with calcium oxide and compost slightly less so. The most positive results were obtained for spring rape as the main crop. An addition of compost, bentonite and calcium oxide to soil had a stronger modifying effect on nitrogen content in plants on soils contaminated by diesel oil than petrol. PMID:19081125

  6. The influence of N-acetyl-L-cysteine on oxidative stress and nitric oxide synthesis in stimulated macrophages treated with a mustard gas analogue

    PubMed Central

    Paromov, Victor; Qui, Min; Yang, Hongsong; Smith, Milton; Stone, William L

    2008-01-01

    Background Sulphur mustard gas, 2, 2'-dichlorodiethyl sulphide (HD), is a chemical warfare agent. Both mustard gas and its monofunctional analogue, 2-chloroethyl ethyl sulphide (CEES), are alkylating agents that react with and diminish cellular thiols and are highly toxic. Previously, we reported that lipopolysaccharide (LPS) significantly enhances the cytotoxicity of CEES in murine RAW 264.7 macrophages and that CEES transiently inhibits nitric oxide (NO) production via suppression of inducible NO synthase (iNOS) protein expression. NO generation is an important factor in wound healing. In this paper, we explored the hypotheses that LPS increases CEES toxicity by increasing oxidative stress and that treatment with N-acetyl-L-cysteine (NAC) would block LPS induced oxidative stress and protect against loss of NO production. NAC stimulates glutathione (GSH) synthesis and also acts directly as a free radical scavenger. The potential therapeutic use of the antibiotic, polymyxin B, was also evaluated since it binds to LPS and could thereby block the enhancement of CEES toxicity by LPS and also inhibit the secondary infections characteristic of HD/CEES wounds. Results We found that 10 mM NAC, when administered simultaneously or prior to treatment with 500 μM CEES, increased the viability of LPS stimulated macrophages. Surprisingly, NAC failed to protect LPS stimulated macrophages from CEES induced loss of NO production. Macrophages treated with both LPS and CEES show increased oxidative stress parameters (cellular thiol depletion and increased protein carbonyl levels). NAC effectively protected RAW 264.7 cells simultaneously treated with CEES and LPS from GSH loss and oxidative stress. Polymyxin B was found to partially block nitric oxide production and diminish CEES toxicity in LPS-treated macrophages. Conclusion The present study shows that oxidative stress is an important mechanism contributing to CEES toxicity in LPS stimulated macrophages and supports the notion

  7. The roles of stored calcium in contractions of cat tracheal smooth muscle produced by electrical stimulation, acetylcholine and high K+.

    PubMed

    Ito, Y; Itoh, T

    1984-11-01

    Effects of direct or indirect (nerve-mediated) muscle stimulation, acetylcholine (ACh), caffeine and procaine on the membrane and mechanical properties of smooth muscle cells of the cat trachea were investigated by means of double sucrose-gap and isometric tension recording methods. Outward current pulses (2 s in duration) applied to the muscle tissue in the presence of tetrodotoxin (10(-7)M), atropine (10(-6)M) and propranolol (10(-6)M) evoked no action potential (spike); however, when the depolarization exceeded 9 mV, a contraction was evoked. The spike and contraction evoked by outward current pulses in the presence of tetraethylammonium (TEA, 10 mM) were suppressed by treatment of the tissue with either Ca2+-free EGTA (2 mM) containing solution or Mn2+ (5 mM). In the presence of procaine (10 mM), outward current pulses evoked an action potential but no contraction. Field stimulation of short duration (50 microseconds) applied to the whole tissue produced an excitation of the intrinsic nerves and evoked excitatory junction potentials (e.j.ps), and when the amplitude of e.j.ps exceeded 4 mV, a twitch contraction occurred. E.j.p. was more effective in producing a contraction than was the membrane depolarization evoked by outward current pulses. Amplitudes of contractions evoked by exogenous ACh (10(-5)M) were much larger than those evoked by 128 mM-[K]0 or caffeine (10 mM), in normal Krebs solution. When the amplitudes of the contractions produced by 128 mM [K]0 were defined as a relative amplitude of 1.0, the mean amplitudes of contraction produced by ACh (10(-5)M) or caffeine were 2.5 +/- 0.20 or 1.2 +/- 0.26, respectively. In Ca2+-free EGTA (2 mM)-containing solution, the contraction induced by 128 mM-[K]0 was rapidly abolished, whereas the contractions evoked by caffeine (10 mM) or the initial phasic contraction produced by ACh (10(-5)M) were largely unaffected. When the amount of Ca2+ stored in the muscle cell was estimated from the amplitude of caffeine

  8. Phosphorylation of calcium/calmodulin-stimulated protein kinase II at T286 enhances invasion and migration of human breast cancer cells

    PubMed Central

    Chi, Mengna; Evans, Hamish; Gilchrist, Jackson; Mayhew, Jack; Hoffman, Alexander; Pearsall, Elizabeth Ann; Jankowski, Helen; Brzozowski, Joshua Stephen; Skelding, Kathryn Anne

    2016-01-01

    Calcium/calmodulin-stimulated protein kinase II (CaMKII) is a multi-functional kinase that controls a range of cellular functions, including proliferation, differentiation and apoptosis. The biological properties of CaMKII are regulated by multi-site phosphorylation. However, the role that CaMKII phosphorylation plays in cancer cell metastasis has not been examined. We demonstrate herein that CaMKII expression and phosphorylation at T286 is increased in breast cancer when compared to normal breast tissue, and that increased CAMK2 mRNA is associated with poor breast cancer patient prognosis (worse overall and distant metastasis free survival). Additionally, we show that overexpression of WT, T286D and T286V forms of CaMKII in MDA-MB-231 and MCF-7 breast cancer cells increases invasion, migration and anchorage independent growth, and that overexpression of the T286D phosphomimic leads to a further increase in the invasive, migratory and anchorage independent growth capacity of these cells. Pharmacological inhibition of CaMKII decreases MDA-MB-231 migration and invasion. Furthermore, we demonstrate that overexpression of T286D, but not WT or T286V-CaMKII, leads to phosphorylation of FAK, STAT5a, and Akt. These results demonstrate a novel function for phosphorylation of CaMKII at T286 in the control of breast cancer metastasis, offering a promising target for the development of therapeutics to prevent breast cancer metastasis. PMID:27605043

  9. Improvement of spatial learning by facilitating large-conductance calcium-activated potassium channel with transcranial magnetic stimulation in Alzheimer's disease model mice.

    PubMed

    Wang, Furong; Zhang, Yu; Wang, Li; Sun, Peng; Luo, Xianwen; Ishigaki, Yasuhito; Sugai, Tokio; Yamamoto, Ryo; Kato, Nobuo

    2015-10-01

    Transcranial magnetic stimulation (TMS) is fragmentarily reported to be beneficial to Alzheimer's patients. Its underlying mechanism was investigated. TMS was applied at 1, 10 or 15 Hz daily for 4 weeks to young Alzheimer's disease model mice (3xTg), in which intracellular soluble amyloid-β is notably accumulated. Hippocampal long-term potentiation (LTP) was tested after behavior. TMS ameliorated spatial learning deficits and enhanced LTP in the same frequency-dependent manner. Activity of the large conductance calcium-activated potassium (Big-K; BK) channels was suppressed in 3xTg mice and recovered by TMS frequency-dependently. These suppression and recovery were accompanied by increase and decrease in cortical excitability, respectively. TMS frequency-dependently enhanced the expression of the activity-dependently expressed scaffold protein Homer1a, which turned out to enhance BK channel activity. Isopimaric acid, an activator of the BK channel, magnified LTP. Amyloid-β lowering was detected after TMS in 3xTg mice. In 3xTg mice with Homer1a knocked out, amyloid-β lowering was not detected, though the TMS effects on BK channel and LTP remained. We concluded that TMS facilitates BK channels both Homer1a-dependently and -independently, thereby enhancing hippocampal LTP and decreasing cortical excitability. Reduced excitability contributed to amyloid-β lowering. A cascade of these correlated processes, triggered by TMS, was likely to improve learning in 3xTg mice.

  10. The Relationship between Membrane Potential and Calcium Dynamics in Glucose-Stimulated Beta Cell Syncytium in Acute Mouse Pancreas Tissue Slices

    PubMed Central

    Miller, Evan W.; Slak Rupnik, Marjan

    2013-01-01

    Oscillatory electrical activity is regarded as a hallmark of the pancreatic beta cell glucose-dependent excitability pattern. Electrophysiologically recorded membrane potential oscillations in beta cells are associated with in-phase oscillatory cytosolic calcium activity ([Ca2+]i) measured with fluorescent probes. Recent high spatial and temporal resolution confocal imaging revealed that glucose stimulation of beta cells in intact islets within acute tissue slices produces a [Ca2+]i change with initial transient phase followed by a plateau phase with highly synchronized [Ca2+]i oscillations. Here, we aimed to correlate the plateau [Ca2+]i oscillations with the oscillations of membrane potential using patch-clamp and for the first time high resolution voltage-sensitive dye based confocal imaging. Our results demonstrated that the glucose-evoked membrane potential oscillations spread over the islet in a wave-like manner, their durations and wave velocities being comparable to the ones for [Ca2+]i oscillations and waves. High temporal resolution simultaneous records of membrane potential and [Ca2+]i confirmed tight but nevertheless limited coupling of the two processes, with membrane depolarization preceding the [Ca2+]i increase. The potassium channel blocker tetraethylammonium increased the velocity at which oscillations advanced over the islet by several-fold while, at the same time, emphasized differences in kinetics of the membrane potential and the [Ca2+]i. The combination of both imaging techniques provides a powerful tool that will help us attain deeper knowledge of the beta cell network. PMID:24324777

  11. Phosphorylation of calcium/calmodulin-stimulated protein kinase II at T286 enhances invasion and migration of human breast cancer cells.

    PubMed

    Chi, Mengna; Evans, Hamish; Gilchrist, Jackson; Mayhew, Jack; Hoffman, Alexander; Pearsall, Elizabeth Ann; Jankowski, Helen; Brzozowski, Joshua Stephen; Skelding, Kathryn Anne

    2016-01-01

    Calcium/calmodulin-stimulated protein kinase II (CaMKII) is a multi-functional kinase that controls a range of cellular functions, including proliferation, differentiation and apoptosis. The biological properties of CaMKII are regulated by multi-site phosphorylation. However, the role that CaMKII phosphorylation plays in cancer cell metastasis has not been examined. We demonstrate herein that CaMKII expression and phosphorylation at T286 is increased in breast cancer when compared to normal breast tissue, and that increased CAMK2 mRNA is associated with poor breast cancer patient prognosis (worse overall and distant metastasis free survival). Additionally, we show that overexpression of WT, T286D and T286V forms of CaMKII in MDA-MB-231 and MCF-7 breast cancer cells increases invasion, migration and anchorage independent growth, and that overexpression of the T286D phosphomimic leads to a further increase in the invasive, migratory and anchorage independent growth capacity of these cells. Pharmacological inhibition of CaMKII decreases MDA-MB-231 migration and invasion. Furthermore, we demonstrate that overexpression of T286D, but not WT or T286V-CaMKII, leads to phosphorylation of FAK, STAT5a, and Akt. These results demonstrate a novel function for phosphorylation of CaMKII at T286 in the control of breast cancer metastasis, offering a promising target for the development of therapeutics to prevent breast cancer metastasis. PMID:27605043

  12. Calcium supplements

    MedlinePlus

    ... TYPES OF CALCIUM SUPPLEMENTS Forms of calcium include: Calcium carbonate: Over-the-counter (OTC) antacid products, such as Tums and Rolaids, contain calcium carbonate. These sources of calcium do not cost much. ...

  13. Stimulation of human neutrophils by soluble and insoluble immunoglobulin aggregates. Secretion of granule constituents and increased oxidation of glucose.

    PubMed Central

    Henson, P M; Oades, Z G

    1975-01-01

    Reaction of human neutrophils with aggregated immunoglobulin on nonphagocytosable surfaces results in secretion of granule enzymes (exocytosis of granules) and stimulation of glucose oxidation by the nexose monophosphate pathway (HMP). The role of HMP stimulation in the enzyme secretion and some requirements for the two neutrophil activities have been examined. It was found that (a) HMP stimulation could be selectively inhibited under conditions where release of granule enzymes remained unchanged or was enhanced, for example, by reduced glucose concentration or by 2-deoxyglucose. (b) Removal of Ca++ and addition of agents which increased the intracellular levels of cyclic AMP (cAMP), however, prevented both activities, while colchicine had greater inhibitory activity on HMP stimulation than upon secretion. (c) Neutrophils incubated in suspension with particulate aggregated gamma-globulin phagocytosed the particles and exhibited a stimulated HMP and released granule enzymes. In contrast, incubation in suspension with soluble aggregated gamma-globulin resulted in the stimulated HMP only. Granule evzymes were not liberated. 300-fold less soluble aggregates bound to a surface, however readily induced exocytosis of granules from adherent neutrophils. This demonstrates the importance of surface effects in the induction of secretion from neutrophils. Aggregated immunoglobulin reacting with neutrophil Fc receptors thus induces both degranulation (exocytosis) and increased HMP activity. The pathways leading to these events are separable although apparently sharing some common steps, including the initiating events. Images PMID:51031

  14. Acceleration of segmental bone regeneration in a rabbit model by strontium-doped calcium polyphosphate scaffold through stimulating VEGF and bFGF secretion from osteoblasts.

    PubMed

    Gu, Zhipeng; Zhang, Xu; Li, Li; Wang, Qiguang; Yu, Xixun; Feng, Ting

    2013-01-01

    The development of suitable bioactive three-dimensional scaffold for the promotion of bone regeneration is critical in bone tissue engineering. The purpose of this study was to investigate in vivo osteogenesis of the porous strontium-doped calcium polyphosphate (SCPP) scaffolds for bone repair, as well as the relationship between osteogenic properties of SCPP scaffolds and the secretion of bFGF and VEGF from osteoblasts stimulated by SCPP. Besides, the advantages of scaffolds seeded with mesenchymal stem cells (MSCs) for bone repair were also studied. Firstly, the bone repair evaluation of scaffolds was performed on a rabbit segmental bony defects model over a period of 16 weeks by histology combined with X-ray microradiography. And then, in order to avoid the influence from the other factors such as hypoxia which emerge in vivo study and affect the secretion of VEGF and bFGF from host cells, human osteoblast-like cells (MG63) were seeded to SCPP, CPP and HA scaffolds in vitro to determine the ability of these scaffolds to stimulate the secretion of angiogenic growth factors (VEGF and bFGF) from MG63 and further explore the reason for the better osteogenic properties of SCPP scaffolds. The histological and X-ray microradiographic results showed that the SCPP scaffolds presented better osteogenic potential than CPP and HA scaffolds, when combined with MSCs, the SCPP scaffolds could further accelerate the bone repair. And the amounts of VEGF measured by ELISA assay in SCPP, CPP and HA groups after cultured for 7 days were about 364.989 pg/mL, 244.035 pg/mL and 232.785 pg/mL, respectively. Accordingly, the amounts of bFGF were about 27.085 pg/mL, 15.727 pg/mL and 8.326 pg/mL. The results revealed that the SCPP scaffolds significantly enhanced the bFGF and VEGF secretion compared with other scaffolds. The results presented in vivo and in vitro study demonstrated that the SCPP could accelerate bone formation through stimulating the secretion of VEGF and bFGF from

  15. Functional Impact of Ryanodine Receptor Oxidation on Intracellular Calcium Regulation in the Heart

    PubMed Central

    Mazurek, Stefan R.

    2016-01-01

    Type 2 ryanodine receptor (RyR2) serves as the major intracellular Ca2+ release channel that drives heart contraction. RyR2 is activated by cytosolic Ca2+ via the process of Ca2+-induced Ca2+ release (CICR). To ensure stability of Ca2+ dynamics, the self-reinforcing CICR must be tightly controlled. Defects in this control cause sarcoplasmic reticulum (SR) Ca2+ mishandling, which manifests in a variety of cardiac pathologies that include myocardial infarction and heart failure. These pathologies are also associated with oxidative stress. Given that RyR2 contains a large number of cysteine residues, it is no surprise that RyR2 plays a key role in the cellular response to oxidative stress. RyR’s many cysteine residues pose an experimental limitation in defining a specific target or mechanism of action for oxidative stress. As a result, the current understanding of redox-mediated RyR2 dysfunction remains incomplete. Several oxidative modifications, including S-glutathionylation and S-nitrosylation, have been suggested playing an important role in the regulation of RyR2 activity. Moreover, oxidative stress can increase RyR2 activity by forming disulfide bonds between two neighboring subunits (intersubunit cross-linking). Since intersubunit interactions within the RyR2 homotetramer complex dictate the channel gating, such posttranslational modification of RyR2 would have a significant impact on RyR2 function and Ca2+ regulation. This review summarizes recent findings on oxidative modifications of RyR2 and discusses contributions of these RyR2 modifications to SR Ca2+ mishandling during cardiac pathologies. PMID:27251471

  16. Complementary Metal Oxide Semiconductor Based Multimodal Sensor for In vivo Brain Function Imaging with a Function for Simultaneous Cell Stimulation

    NASA Astrophysics Data System (ADS)

    Tagawa, Ayato; Mitani, Masahiro; Minami, Hiroki; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Ohta, Jun

    2010-04-01

    We have developed a multimodal complementary metal oxide semiconductor (CMOS) sensor device embedded with Au electrodes for fluorescent imaging and cell stimulation in the deep brain of mice. The Au electrodes were placed on the pixel array of the image sensor. Windows over the photodiodes were opened in the electrode area for simultaneous fluorescent imaging and cell stimulation in the same area of the brain tissue. The sensor chip was shaped like a shank and was packaged by two packaging methods for high strength or minimal invasion. The experimental results showed that the 90 ×90 µm2 Au electrodes with windows were capable of injecting theta burst stimulation (TBS)-like current pulses at 0.2-1 mA in a saline solution. We successfully demonstrated that fluorescent imaging and TBS-like current injection can be simultaneously performed in the electrode area of a brain phantom.

  17. Complementary Metal Oxide Semiconductor Based Multimodal Sensor for In vivo Brain Function Imaging with a Function for Simultaneous Cell Stimulation

    NASA Astrophysics Data System (ADS)

    Ayato Tagawa,; Masahiro Mitani,; Hiroki Minami,; Toshihiko Noda,; Kiyotaka Sasagawa,; Takashi Tokuda,; Jun Ohta,

    2010-04-01

    We have developed a multimodal complementary metal oxide semiconductor (CMOS) sensor device embedded with Au electrodes for fluorescent imaging and cell stimulation in the deep brain of mice. The Au electrodes were placed on the pixel array of the image sensor. Windows over the photodiodes were opened in the electrode area for simultaneous fluorescent imaging and cell stimulation in the same area of the brain tissue. The sensor chip was shaped like a shank and was packaged by two packaging methods for high strength or minimal invasion. The experimental results showed that the 90 × 90 μm2 Au electrodes with windows were capable of injecting theta burst stimulation (TBS)-like current pulses at 0.2-1 mA in a saline solution. We successfully demonstrated that fluorescent imaging and TBS-like current injection can be simultaneously performed in the electrode area of a brain phantom.

  18. On the preparation of TiAl alloy by direct reduction of the oxide mixtures in calcium chloride melt

    SciTech Connect

    Prabhat K. Tripathy; Derek J. Fray

    2011-11-01

    electrode in a pool of molten calcium chloride at a temperature of 9000C. The dominant mechanism of the oxygen removal was the ionization of oxygen followed by its subsequent discharge, as CO2/CO, at the anode surface. The removal of oxygen from the oxide mixture helped form the alloy in situ. The presentation shall cover the detailed experimental results pertaining to the preparation, evaluation and characterization of Ti-47Al-2Nb-2Cr (atom%) alloy.

  19. Chronic stimulation of farnesoid X receptor impairs nitric oxide sensitivity of vascular smooth muscle.

    PubMed

    Kida, Taiki; Murata, Takahisa; Hori, Masatoshi; Ozaki, Hiroshi

    2009-01-01

    Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily that is highly expressed in enterohepatic tissue, is implicated in bile acid, lipid, and glucose metabolisms. Although recent studies showed that FXR is also expressed in vascular endothelial cells and smooth muscle cells, its physiological and/or pathological roles in vasculature tissue remain unknown. The aim of this study is to examine the chronic effect of synthetic FXR agonist GW4064 on vascular contraction and endothelium-dependent relaxation using tissue culture procedure. In cultured rabbit mesenteric arteries, the treatment with 0.1-10 microM GW4064 for 7 days did not influence vascular contractility induced by high K(+) (15-65 mM), norepinephrine (0.1-100 microM), and endothelin-1 (0.1-100 nM). However, the chronic treatment with GW4064 (1-10 microM for 7 days) dose dependently impaired endothelium-dependent relaxation induced by substance P (0.1-30 nM). In hematoxylin-eosin cross sectioning and en face immunostaining, GW4064 had no effects on the morphology of endothelial and smooth muscle cells. In endothelium-denuded arteries treated with GW4064 (1-10 microM) for 7 days, 3 nM-100 microM sodium nitroprusside-induced vasorelaxation, but not membrane-permeable cGMP analog 8-bromoguanosine-cGMP (8-Br-cGMP; 1-100 microM)-induced vasorelaxation, was significantly impaired. In these GW4064-treated arteries, 1 muM sodium nitroprusside-induced intracellular cGMP elevations were impaired. In RT-PCR, any changes were detected in mRNA expression level of alpha(1)- and beta(1)-subunit of soluble guanylyl cyclase. These results suggest that chronic stimulation of FXR impairs endothelium-dependent relaxation, which is due to decreased sensitivity of smooth muscle cells to nitric oxide.

  20. Effects of β-Glucan on the Release of Nitric Oxide by Macrophages Stimulated with Lipopolysaccharide

    PubMed Central

    Choi, E. Y.; Lee, S. S.; Hyeon, J. Y.; Choe, S. H.; Keum, B. R.; Lim, J. M.; Park, D. C.; Choi, I. S.; Cho, K. K.

    2016-01-01

    This research analyzed the effect of β-glucan that is expected to alleviate the production of the inflammatory mediator in macrophagocytes, which are processed by the lipopolysaccharide (LPS) of Escherichia. The incubated layer was used for a nitric oxide (NO) analysis. The DNA-binding activation of the small unit of nuclear factor-κB was measured using the enzyme-linked immunosorbent assay-based kit. In the RAW264.7 cells that were vitalized by Escherichia coli (E. coli) LPS, the β-glucan inhibited both the combatant and rendering phases of the inducible NO synthase (iNOS)-derived NO. β-Glucan increased the expression of the heme oxygenase-1 (HO-1) in the cells that were stimulated by E. coli LPS, and the HO-1 activation was inhibited by the tin protoporphyrin IX (SnPP). This shows that the NO production induced by LPS is related to the inhibition effect of β-glucan. The phosphorylation of c-Jun N-terminal kinases (JNK) and the p38 induced by the LPS were not influenced by the β-glucan, and the inhibitory κB-α (IκB-α) decomposition was not influenced either. Instead, β-glucan remarkably inhibited the phosphorylation of the signal transducer and activator of transcription-1 (STAT1) that was induced by the E. coli LPS. Overall, the β-glucan inhibited the production of NO in macrophagocytes that was vitalized by the E .coli LPS through the HO-1 induction and the STAT1 pathways inhibition in this research. As the host immune response control by β-glucan weakens the progress of the inflammatory disease, β-glucan can be used as an effective immunomodulator. PMID:27488844

  1. Melatonin decreases muscular oxidative stress and inflammation induced by strenuous exercise and stimulates growth factor synthesis.

    PubMed

    Borges, Leandro da Silva; Dermargos, Alexandre; da Silva Junior, Edenilson Pinto; Weimann, Eleine; Lambertucci, Rafael Herling; Hatanaka, Elaine

    2015-03-01

    Strenuous exercise is detrimental to athletes because of the overproduction of reactive oxygen species. Melatonin, a classic antioxidant, has been shown to exhibit beneficial effects regarding intense exercise and tissue repair. In this study, we evaluated the onset and resolution of inflammation in melatonin-treated and nontreated rats subjected to a strenuous exercise session. We also analyzed the formation of thiobarbituric acid reactive substances (TBARS) and the activities of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD). Control and treated rats were subjected to exhaustive exercise after a period of 10 days of melatonin treatment (20 mg/dL). Plasma and muscle levels of tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), cytokine-induced neutrophil chemoattractant-2-alpha/beta (CINC-2α/β), l-selectin, macrophage inflammatory protein-3-alpha (MIP-3α), and vascular endothelial growth factor (VEGF) were measured prior to, immediately after, and 2 hr after exercise. Our data revealed decreases in the muscle concentrations of IL-1β (35%), TNF-α (13%), IL-6 (48%), and TBARS (40%) in the melatonin-treated group compared with the control group. We also observed decreases in the plasma concentrations of IL-1β (17%) in the melatonin-treated group. VEGF-α concentrations and SOD activity increased by 179% and 22%, respectively, in the melatonin-treated group compared with the control group. We concluded that muscle inflammation and oxidative stress resulting from exhaustive exercise were less severe in the muscles of melatonin-treated animals than in the muscles of control animals. Thus, melatonin treatment may reverse exercise-induced skeletal muscle inflammation and stimulate growth factor synthesis.

  2. Mutant Huntingtin and Elusive Defects in Oxidative Metabolism and Mitochondrial Calcium Handling.

    PubMed

    Brustovetsky, Nickolay

    2016-07-01

    Elongation of a polyglutamine (polyQ) stretch in huntingtin protein (Htt) is linked to Huntington's disease (HD) pathogenesis. The mutation in Htt correlates with neuronal dysfunction in the striatum and cerebral cortex and eventually leads to neuronal cell death. The exact mechanisms of the injurious effect of mutant Htt (mHtt) on neurons are not completely understood but might include aberrant gene transcription, defective autophagy, abnormal mitochondrial biogenesis, anomalous mitochondrial dynamics, and trafficking. In addition, deficiency in oxidative metabolism and defects in mitochondrial Ca(2+) handling are considered essential contributing factors to neuronal dysfunction in HD and, consequently, in HD pathogenesis. Since the discovery of the mutation in Htt, the questions whether mHtt affects oxidative metabolism and mitochondrial Ca(2+) handling and, if it does, what mechanisms could be involved were in focus of numerous investigations. However, despite significant research efforts, the detrimental effect of mHtt and the mechanisms by which mHtt might impair oxidative metabolism and mitochondrial Ca(2+) handling remain elusive. In this paper, I will briefly review studies aimed at clarifying the consequences of mHtt interaction with mitochondria and discuss experimental results supporting or arguing against the mHtt effects on oxidative metabolism and mitochondrial Ca(2+) handling.

  3. Reducing nitrous oxide emissions by changing N fertiliser use from calcium ammonium nitrate (CAN) to urea based formulations.

    PubMed

    Harty, M A; Forrestal, P J; Watson, C J; McGeough, K L; Carolan, R; Elliot, C; Krol, D; Laughlin, R J; Richards, K G; Lanigan, G J

    2016-09-01

    The accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food demand, is the primary driver for increased atmospheric concentrations of nitrous oxide (N2O). The IPCC default emission factor (EF) for N2O from soils is 1% of the N applied, irrespective of its form. However, N2O emissions tend to be higher from nitrate-containing fertilisers e.g. calcium ammonium nitrate (CAN) compared to urea, particularly in regions, which have mild, wet climates and high organic matter soils. Urea can be an inefficient N source due to NH3 volatilisation, but nitrogen stabilisers (urease and nitrification inhibitors) can improve its efficacy. This study evaluated the impact of switching fertiliser formulation from calcium ammonium nitrate (CAN) to urea-based products, as a potential mitigation strategy to reduce N2O emissions at six temperate grassland sites on the island of Ireland. The surface applied formulations included CAN, urea and urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N2O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N2O emission factor (EF) from CAN averaged 1.49% overall sites, but was highly variable, ranging from 0.58% to 3.81. Amending urea with NBPT, to reduce ammonia volatilisation, resulted in an average EF of 0.40% (ranging from 0.21 to 0.69%)-compared to an average EF of 0.25% for urea (ranging from 0.1 to 0.49%), with both fertilisers significantly lower and less variable than CAN. Cumulative N2O emissions from urea amended with both NBPT and DCD were not significantly different from background levels. Switching from CAN to stabilised urea formulations was found to be an effective strategy to reduce N2O emissions, particularly in wet, temperate grassland.

  4. Reducing nitrous oxide emissions by changing N fertiliser use from calcium ammonium nitrate (CAN) to urea based formulations.

    PubMed

    Harty, M A; Forrestal, P J; Watson, C J; McGeough, K L; Carolan, R; Elliot, C; Krol, D; Laughlin, R J; Richards, K G; Lanigan, G J

    2016-09-01

    The accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food demand, is the primary driver for increased atmospheric concentrations of nitrous oxide (N2O). The IPCC default emission factor (EF) for N2O from soils is 1% of the N applied, irrespective of its form. However, N2O emissions tend to be higher from nitrate-containing fertilisers e.g. calcium ammonium nitrate (CAN) compared to urea, particularly in regions, which have mild, wet climates and high organic matter soils. Urea can be an inefficient N source due to NH3 volatilisation, but nitrogen stabilisers (urease and nitrification inhibitors) can improve its efficacy. This study evaluated the impact of switching fertiliser formulation from calcium ammonium nitrate (CAN) to urea-based products, as a potential mitigation strategy to reduce N2O emissions at six temperate grassland sites on the island of Ireland. The surface applied formulations included CAN, urea and urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N2O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N2O emission factor (EF) from CAN averaged 1.49% overall sites, but was highly variable, ranging from 0.58% to 3.81. Amending urea with NBPT, to reduce ammonia volatilisation, resulted in an average EF of 0.40% (ranging from 0.21 to 0.69%)-compared to an average EF of 0.25% for urea (ranging from 0.1 to 0.49%), with both fertilisers significantly lower and less variable than CAN. Cumulative N2O emissions from urea amended with both NBPT and DCD were not significantly different from background levels. Switching from CAN to stabilised urea formulations was found to be an effective strategy to reduce N2O emissions, particularly in wet, temperate grassland. PMID:27155080

  5. Evidence that additional mechanisms to cyclic GMP mediate the decrease in intracellular calcium and relaxation of rabbit aortic smooth muscle to nitric oxide

    PubMed Central

    Weisbrod, Robert M; Griswold, Mark C; Yaghoubi, Mohammad; Komalavilas, Padmini; Lincoln, Thomas M; Cohen, Richard A

    1998-01-01

    The role of cyclic GMP in the ability of nitric oxide (NO) to decrease intracellular free calcium concentration [Ca2+]i and divalent cation influx was studied in rabbit aortic smooth muscle cells in primary culture. In cells stimulated with angiotensin II (AII, 10−7 M), NO (10−10–10−6 M) increased cyclic GMP levels measured by radioimmunoassay and decreased [Ca2+]i and cation influx as indicated by fura-2 fluorimetry.Zaprinast (10−4 M), increased NO-stimulated levels of cyclic GMP by 3–20 fold. Although the phosphodiesterase inhibitor lowered the level of [Ca2+]i reached after administration of NO, the initial decreases in [Ca2+]i initiated by NO were not significantly different in magnitude or duration from those that occurred in the absence of zaprinast.The guanylyl cyclase inhibitor, H-(1,2,4) oxadiazolo(4,3-a) quinoxallin-1-one (ODQ, 10−5 M), blocked cyclic GMP accumulation and activation of protein kinase G, as measured by back phosphorylation of the inositol trisphosphate receptor. ODQ and Rp-8-Br-cyclic GMPS, a protein kinase G inhibitor, decreased the effects of NO, 10−10–10−8 M, but the decrease in [Ca2+]i or cation influx caused by higher concentrations of NO (10−7–10−6 M) were unaffected. Relaxation of intact rabbit aorta rings to NO (10−7–10−5 M) also persisted in the presence of ODQ without a significant increase in cyclic GMP. Rp-8-Br-cyclic GMPS blocked the decreases in cation influx caused by a cell permeable cyclic GMP analog, but ODQ and/or the protein kinase G inhibitor had no significant effect on the decrease caused by NO.Although inhibitors of cyclic GMP, protein kinase G and phosphodiesterase can be shown to affect the decrease in [Ca2+]i and cation influx via protein kinase G, these studies indicate that when these mechanisms are blocked, cyclic GMP-independent mechanisms also contribute significantly to the decrease in [Ca2+]i and smooth muscle relaxation to NO. PMID:9886761

  6. Iron isotope fractionation during microbially stimulated Fe(II) oxidation and Fe(III) precipitation

    USGS Publications Warehouse

    Balci, N.; Bullen, T.D.; Witte-Lien, K.; Shanks, Wayne C.; Motelica, M.; Mandernack, K.W.

    2006-01-01

    Interpretation of the origins of iron-bearing minerals preserved in modern and ancient rocks based on measured iron isotope ratios depends on our ability to distinguish between biological and non-biological iron isotope fractionation processes. In this study, we compared 56Fe/54Fe ratios of coexisting aqueous iron (Fe(II)aq, Fe(III)aq) and iron oxyhydroxide precipitates (Fe(III)ppt) resulting from the oxidation of ferrous iron under experimental conditions at low pH (<3). Experiments were carried out using both pure cultures of Acidothiobacillus ferrooxidans and sterile controls to assess possible biological overprinting of non-biological fractionation, and both SO42- and Cl- salts as Fe(II) sources to determine possible ionic/speciation effects that may be associated with oxidation/precipitation reactions. In addition, a series of ferric iron precipitation experiments were performed at pH ranging from 1.9 to 3.5 to determine if different precipitation rates cause differences in the isotopic composition of the iron oxyhydroxides. During microbially stimulated Fe(II) oxidation in both the sulfate and chloride systems, 56Fe/54Fe ratios of residual Fe(II)aq sampled in a time series evolved along an apparent Rayleigh trend characterized by a fractionation factor ??Fe(III)aq-Fe(II)aq???1.0022. This fractionation factor was significantly less than that measured in our sterile control experiments (???1.0034) and that predicted for isotopic equilibrium between Fe(II)aq and Fe(III)aq (???1.0029), and thus might be interpreted to reflect a biological isotope effect. However, in our biological experiments the measured difference in 56Fe/54Fe ratios between Fe(III)aq, isolated as a solid by the addition of NaOH to the final solution at each time point under N2-atmosphere, and Fe(II)aq was in most cases and on average close to 2.9??? (??Fe(III)aq-Fe(II)aq ???1.0029), consistent with isotopic equilibrium between Fe(II)aq and Fe(III)aq. The ferric iron precipitation experiments

  7. Nitric oxide inhibited the melanophore aggregation induced by extracellular calcium concentration in snakehead fish, Channa punctatus.

    PubMed

    Biswas, Saikat P; Palande, Nikhil V; Jadhao, Arun G

    2011-12-01

    We studied the role of nitric oxide (NO) and extra-cellular Ca(2+) on the melanophores in Indian snakehead teleost, Channa punctatus. Increase of Ca(2+) level in the external medium causes pigment aggregation in melanophores. This pigment-aggregating effect was found to be inhibited when the external medium contained spontaneous NO donor, sodium nitro prusside (SNP) at all the levels of concentration tested. Furthermore, it has been observed that SNP keeps the pigment in dispersed state even after increasing the amount of Ca(2+). In order to test whether NO donor SNP causes dispersion of pigments or not is checked by adding the inhibitor of nitric oxide synthase, N-omega-Nitro-L-arginine (L-NNA) in the medium. It has been noted that the inhibitor L-NNA blocked the effect of NO donor SNP causing aggregation of pigments. In that way NO is inhibiting the effect of extracellular Ca(2+), keeping the pigment dispersed.

  8. Changes in Stomatal Behavior and Guard Cell Cytosolic Free Calcium in Response to Oxidative Stress.

    PubMed Central

    McAinsh, M. R.; Clayton, H.; Mansfield, T. A.; Hetherington, A. M.

    1996-01-01

    We have investigated the cellular basis for the effects of oxidative stress on stomatal behavior using stomatal bioassay and ratio photometric techniques. Two oxidative treatments were employed in this study: (a) methyl viologen, which generates superoxide radicals, and (b) H2O2. Both methyl viologen and H2O2 inhibited stomatal opening and promoted stomatal closure. At concentrations [less than or equal to]10-5 M, the effects of methyl viologen and H2O2 on stomatal behavior were reversible and were abolished by 2 mM EGTA or 10 [mu]M verapamil. In addition, at 10-5 M, i.e. the maximum concentration at which the effects of the treatments were prevented by EGTA or verapamil, methyl viologen and H2O2 caused an increase in guard cell cytosolic free Ca2+ ([Ca2+]i), which was abolished in the presence of EGTA. Therefore, at low concentrations of methyl viologen and H2O2, removal of extracellular Ca2+ prevented both the oxidative stress-induced changes in stomatal aperture and the associated increases in [Ca2+]i. This suggests that in this concentration range the effects of the treatments are Ca2+-dependent and are mediated by changes in [Ca2+]i. In contrast, at concentrations of methyl viologan and H2O2 > 10-5 M, EGTA and verapamil had no effect. However, in this concentration range the effects of the treatments were irreversible and correlated with a marked reduction in membrane integrity and guard cell viability. This suggests that at high concentrations the effects of methyl viologen and H2O2 may be due to changes in membrane integrity. The implications of oxidative stress-induced increases in [Ca2+]i and the possible disruption of guard-cell Ca2+ homeostasis are discussed in relation to the processes of Ca2+-based signal transduction in stomatal guard cells and the control of stomatal aperture. PMID:12226345

  9. Dichlorodifluoromethane decomposition to CO2 with simultaneous halogen fixation by calcium oxide based materials.

    PubMed

    Tamai, Tsukasa; Inazu, Koji; Aika, Ken-ichi

    2006-02-01

    The decomposition of CCl2F2 to CO2 and accompanying halogen fixation by a CaO based material was studied. To improve the low reactivity of CaO, a consequence of its low surface acidity, transition metal oxides were added. Impregnation of metal acetylacetonate followed by removal of the ligand under vacuum was found to be an effective method. This method resulted in the formation of carbonaceous species and the reduction of metal oxide to metal, both of which were thought to initiate the decomposition reaction. The reactivity of these materials (MOx(a)/CaO-vac) was found to be in the following order: M = Ni > Cu > V = Fe > Mn > Co > Ca. In particular, nickel supported on CaO was most effective for the decomposition of CCl2F2. During the preparation, nickel oxide was reduced to the metal phase. CCl2F2 was decomposed to CO2 with a small amount of CO, and halogens were fixed as CaFCl, without significant deactivation at 723 K.

  10. The isolation of nuclear envelopes. Effects of thiol-group oxidation and of calcium ions.

    PubMed

    Comerford, S A; McLuckie, I F; Gorman, M; Scott, K A; Agutter, P S

    1985-02-15

    The effects of (a) oxidative cross-linking of protein thiol groups and (b) the presence or absence of Ca2+ ions on rat liver nuclear-envelope isolation were studied. Two envelope-isolation procedures were compared: a well characterized low-ionic-strength method and a recently developed high-ionic-strength method. The latter method seems preferable to the former in respect of lower intranuclear contamination of the envelopes, suppression of endogenous serine proteinase, and maintenance of high specific activities of envelope-associated enzymes. In both procedures, however, the presence of Ca2+ gave rise to a rapid, apparently irreversible, contamination of the envelopes by intranuclear material. This effect was half-maximal at 20 microM-Ca2+. In addition, the envelopes became contaminated with intranuclear material by a Ca2+-independent mechanism, apparently resulting from N-ethylmaleimide-sensitive intermolecular disulphide-bond formation. This oxidative process seemed to have two major kinetic components (half-life, t1/2, approx. 2 min and 10 min). In view of these findings, it is recommended that (i) for most purposes, nuclear envelopes be isolated by the newly developed high-ionic-strength procedure, (ii) irrespective of the method used, Ca2+-chelators be included in all the buffers, (iii) thiol-group oxidation be prevented or reversed during the procedure.

  11. The isolation of nuclear envelopes. Effects of thiol-group oxidation and of calcium ions.

    PubMed Central

    Comerford, S A; McLuckie, I F; Gorman, M; Scott, K A; Agutter, P S

    1985-01-01

    The effects of (a) oxidative cross-linking of protein thiol groups and (b) the presence or absence of Ca2+ ions on rat liver nuclear-envelope isolation were studied. Two envelope-isolation procedures were compared: a well characterized low-ionic-strength method and a recently developed high-ionic-strength method. The latter method seems preferable to the former in respect of lower intranuclear contamination of the envelopes, suppression of endogenous serine proteinase, and maintenance of high specific activities of envelope-associated enzymes. In both procedures, however, the presence of Ca2+ gave rise to a rapid, apparently irreversible, contamination of the envelopes by intranuclear material. This effect was half-maximal at 20 microM-Ca2+. In addition, the envelopes became contaminated with intranuclear material by a Ca2+-independent mechanism, apparently resulting from N-ethylmaleimide-sensitive intermolecular disulphide-bond formation. This oxidative process seemed to have two major kinetic components (half-life, t1/2, approx. 2 min and 10 min). In view of these findings, it is recommended that (i) for most purposes, nuclear envelopes be isolated by the newly developed high-ionic-strength procedure, (ii) irrespective of the method used, Ca2+-chelators be included in all the buffers, (iii) thiol-group oxidation be prevented or reversed during the procedure. PMID:2983687

  12. Mitochondria: the calcium connection.

    PubMed

    Contreras, Laura; Drago, Ilaria; Zampese, Enrico; Pozzan, Tullio

    2010-01-01

    Calcium handling by mitochondria is a key feature in cell life. It is involved in energy production for cell activity, in buffering and shaping cytosolic calcium rises and also in determining cell fate by triggering or preventing apoptosis. Both mitochondria and the mechanisms involved in the control of calcium homeostasis have been extensively studied, but they still provide researchers with long-standing or even new challenges. Technical improvements in the tools employed for the investigation of calcium dynamics have been-and are still-opening new perspectives in this field, and more prominently for mitochondria. In this review we present a state-of-the-art toolkit for calcium measurements, with major emphasis on the advantages of genetically encoded indicators. These indicators can be efficiently and selectively targeted to specific cellular sub-compartments, allowing previously unavailable high-definition calcium dynamic studies. We also summarize the main features of cellular and, in more detail, mitochondrial calcium handling, especially focusing on the latest breakthroughs in the field, such as the recent direct characterization of the calcium microdomains that occur on the mitochondrial surface upon cellular stimulation. Additionally, we provide a major example of the key role played by calcium in patho-physiology by briefly describing the extensively reported-albeit highly controversial-alterations of calcium homeostasis in Alzheimer's disease, casting lights on the possible alterations in mitochondrial calcium handling in this pathology.

  13. Long-term use of angiotensin II receptor antagonists and calcium-channel antagonists in Algerian hypertensive patients: effects on metabolic and oxidative parameters.

    PubMed

    El Hassar, Chafika; Merzouk, Hafida; Merzouk, Sid Ahmed; Malti, Nassima; Meziane, Abderrahim; Narce, Michel

    2015-02-01

    The effects of calcium antagonists (amlodipine) and angiotensin II receptor antagonists (telmisartan) on lipid profile and oxidative markers were investigated in Algerian hypertensive patients. At the beginning and after 1 year of antihypertensive therapy, blood samples are collected for determination of biochemical parameters (glucose, cholesterol, triglycerides, urea, creatinine) and oxidative markers (malondialdehyde, carbonyl proteins, nitric oxide, superoxide anion, vitamin C, glutathione, catalase, superoxide dismutase). The results of this study indicate that telmisartan and amlodipine are effective antihypertensive agents in the treatment of hypertension because a significant reduction in systolic and diastolic blood pressure was observed in all hypertensive patients after 1 year of treatment. Our results show also that telmisartan and amlodipine treatments counteracted hypertension-dependent lipid abnormalities and oxidative stress. Telmisartan treatment appears to be more efficient than amlodipine treatment. In addition, telmisartan, which reversed all lipid and redox changes associated with hypertension, should be prescribed, especially in hypertensive patients with hypertriglyceridemia and with severe oxidative stress. PMID:25499852

  14. Nitric oxide signals are interlinked with calcium signals in normal pancreatic stellate cells upon oxidative stress and inflammation

    PubMed Central

    2016-01-01

    The mammalian diffuse stellate cell system comprises retinoid-storing cells capable of remarkable transformations from a quiescent to an activated myofibroblast-like phenotype. Activated pancreatic stellate cells (PSCs) attract attention owing to the pivotal role they play in development of tissue fibrosis in chronic pancreatitis and pancreatic cancer. However, little is known about the actual role of PSCs in the normal pancreas. These enigmatic cells have recently been shown to respond to physiological stimuli in a manner that is markedly different from their neighbouring pancreatic acinar cells (PACs). Here, we demonstrate the capacity of PSCs to generate nitric oxide (NO), a free radical messenger mediating, for example, inflammation and vasodilatation. We show that production of cytosolic NO in PSCs is unambiguously related to cytosolic Ca2+ signals. Only stimuli that evoke Ca2+ signals in the PSCs elicit consequent NO generation. We provide fresh evidence for the striking difference between signalling pathways in PSCs and adjacent PACs, because PSCs, in contrast to PACs, generate substantial Ca2+-mediated and NOS-dependent NO signals. We also show that inhibition of NO generation protects both PSCs and PACs from necrosis. Our results highlight the interplay between Ca2+ and NO signalling pathways in cell–cell communication, and also identify a potential therapeutic target for anti-inflammatory therapies. PMID:27488376

  15. Gaseous nitrogen oxides stimulate cell cycle progression by retinoblastoma phosphorylation via activation of cyclins/Cdks [correction].

    PubMed

    Chen, Jing-Hsien; Tseng, Tsui-Hwa; Ho, Yung-Chyan; Lin, Hui-Hsuan; Lin, Wea-Lung; Wang, Chau-Jong

    2003-11-01

    Nitrogen oxides (NOx) are important indoor and outdoor air pollutants. Many studies have indicated that NOx gas causes lung tissue damage by its oxidation properties and its free radicals. In a previous study we demonstrated that NOx gas induced proliferation of human lung fibroblast MRC-5 cells. In this study we show that NOx gas stimulates MRC-5 cell proliferation by retinoblastoma (Rb) phosphorylation via activation of cyclin-cell division protein kinase (cdk) complexes [correction]. Western blot and immunoprecipitation data showed that NOx gas increased the expressions of cyclinA/cdk2, cyclinD1/cdk4, and cyclinE/cdk2 complexes in the cells at 9 h after treatment. The levels of phospho-Rb were also increased and cdk inhibitors (CKIs) p27 and p16 were apparently decreased. These data suggested that NOx gas stimulates cell-cycle progression by Rb phosphorylation via activation of cyclin-cdk complexes and inhibition of CKIs. In conclusion, the NOx-gas that induced lung fibroblast cell proliferation by stimulation of cell-cycle progression may contribute to lung fibrosis by NOx pollutants.

  16. The nitric oxide donor sodium nitroprusside stimulates the Na+-K+ pump in isolated rabbit cardiac myocytes.

    PubMed

    William, Maged; Vien, Jimmy; Hamilton, Elisha; Garcia, Alvaro; Bundgaard, Henning; Clarke, Ronald J; Rasmussen, Helge H

    2005-06-15

    Nitric oxide (NO) affects the membrane Na(+)-K(+) pump in a tissue-dependent manner. Stimulation of intrinsic pump activity, stimulation secondary to NO-induced Na(+) influx into cells or inhibition has been reported. We used the whole-cell patch clamp technique to measure electrogenic Na(+)-K(+) pump current (I(p)) in rabbit ventricular myocytes. Myocytes were voltage clamped with wide-tipped patch pipettes to achieve optimal perfusion of the intracellular compartment, and I(p) was identified as the shift in holding current induced by 100 microm ouabain. The NO donor sodium nitroprusside (SNP) in concentrations of 1, 10, 50 or 100 microm induced a significant increase in I(p) when the intracellular compartment was perfused with pipette solutions containing 10 mm Na(+), a concentration near physiological levels. SNP had no effect when the pump was near-maximally activated by 80 mm Na(+) in pipette solutions. Stimulation persisted in the absence of extracellular Na(+), indicating its independence of transmembrane Na(+) influx. The SNP-induced pump stimulation was abolished by inhibition of soluble guanylyl cyclase (sGC) with 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one, by inhibition of protein kinase G (PKG) with KT-5823 or by inhibition of protein phosphatase with okadaic acid. Inclusion of the non-hydrolysable cGMP analogue 8pCPT-cGMP, activated recombinant PKG or the sGC-activator YC-1 in patch pipette filling solutions reproduced the SNP-induced pump stimulation. Pump stimulation induced by YC-1 was dependent on the Na(+) concentration but not the K(+) concentration in pipette filling solutions, suggesting an altered sensitivity of the Na(+)-K(+) pump to intracellular Na(+). PMID:15817632

  17. Nitric Oxide Synthase 1 Modulates Basal and β-Adrenergic-Stimulated Contractility by Rapid and Reversible Redox-Dependent S-Nitrosylation of the Heart

    PubMed Central

    Vielma, Alejandra Z.; León, Luisa; Fernández, Ignacio C.; González, Daniel R.

    2016-01-01

    S-nitrosylation of several Ca2+ regulating proteins in response to β-adrenergic stimulation was recently described in the heart; however the specific nitric oxide synthase (NOS) isoform and signaling pathways responsible for this modification have not been elucidated. NOS-1 activity increases inotropism, therefore, we tested whether β-adrenergic stimulation induces NOS-1-dependent S-nitrosylation of total proteins, the ryanodine receptor (RyR2), SERCA2 and the L-Type Ca2+ channel (LTCC). In the isolated rat heart, isoproterenol (10 nM, 3-min) increased S-nitrosylation of total cardiac proteins (+46±14%) and RyR2 (+146±77%), without affecting S-nitrosylation of SERCA2 and LTCC. Selective NOS-1 blockade with S-methyl-L-thiocitrulline (SMTC) and Nω-propyl-l-arginine decreased basal contractility and relaxation (−25–30%) and basal S-nitrosylation of total proteins (−25–60%), RyR2, SERCA2 and LTCC (−60–75%). NOS-1 inhibition reduced (−25–40%) the inotropic response and protein S-nitrosylation induced by isoproterenol, particularly that of RyR2 (−85±7%). Tempol, a superoxide scavenger, mimicked the effects of NOS-1 inhibition on inotropism and protein S-nitrosylation; whereas selective NOS-3 inhibitor L-N5-(1-Iminoethyl)ornithine had no effect. Inhibition of NOS-1 did not affect phospholamban phosphorylation, but reduced its oligomerization. Attenuation of contractility was abolished by PKA blockade and unaffected by guanylate cyclase inhibition. Additionally, in isolated mouse cardiomyocytes, NOS-1 inhibition or removal reduced the Ca2+-transient amplitude and sarcomere shortening induced by isoproterenol or by direct PKA activation. We conclude that 1) normal cardiac performance requires basal NOS-1 activity and S-nitrosylation of the calcium-cycling machinery; 2) β-adrenergic stimulation induces rapid and reversible NOS-1 dependent, PKA and ROS-dependent, S-nitrosylation of RyR2 and other proteins, accounting for about one third of its

  18. Nitric Oxide Synthase 1 Modulates Basal and β-Adrenergic-Stimulated Contractility by Rapid and Reversible Redox-Dependent S-Nitrosylation of the Heart.

    PubMed

    Vielma, Alejandra Z; León, Luisa; Fernández, Ignacio C; González, Daniel R; Boric, Mauricio P

    2016-01-01

    S-nitrosylation of several Ca2+ regulating proteins in response to β-adrenergic stimulation was recently described in the heart; however the specific nitric oxide synthase (NOS) isoform and signaling pathways responsible for this modification have not been elucidated. NOS-1 activity increases inotropism, therefore, we tested whether β-adrenergic stimulation induces NOS-1-dependent S-nitrosylation of total proteins, the ryanodine receptor (RyR2), SERCA2 and the L-Type Ca2+ channel (LTCC). In the isolated rat heart, isoproterenol (10 nM, 3-min) increased S-nitrosylation of total cardiac proteins (+46±14%) and RyR2 (+146±77%), without affecting S-nitrosylation of SERCA2 and LTCC. Selective NOS-1 blockade with S-methyl-L-thiocitrulline (SMTC) and Nω-propyl-l-arginine decreased basal contractility and relaxation (-25-30%) and basal S-nitrosylation of total proteins (-25-60%), RyR2, SERCA2 and LTCC (-60-75%). NOS-1 inhibition reduced (-25-40%) the inotropic response and protein S-nitrosylation induced by isoproterenol, particularly that of RyR2 (-85±7%). Tempol, a superoxide scavenger, mimicked the effects of NOS-1 inhibition on inotropism and protein S-nitrosylation; whereas selective NOS-3 inhibitor L-N5-(1-Iminoethyl)ornithine had no effect. Inhibition of NOS-1 did not affect phospholamban phosphorylation, but reduced its oligomerization. Attenuation of contractility was abolished by PKA blockade and unaffected by guanylate cyclase inhibition. Additionally, in isolated mouse cardiomyocytes, NOS-1 inhibition or removal reduced the Ca2+-transient amplitude and sarcomere shortening induced by isoproterenol or by direct PKA activation. We conclude that 1) normal cardiac performance requires basal NOS-1 activity and S-nitrosylation of the calcium-cycling machinery; 2) β-adrenergic stimulation induces rapid and reversible NOS-1 dependent, PKA and ROS-dependent, S-nitrosylation of RyR2 and other proteins, accounting for about one third of its inotropic effect.

  19. Poly(ethylene oxide)-b-poly(3-sulfopropyl methacrylate) block copolymers for calcium phosphate mineralization and biofilm inhibition.

    PubMed

    Mai, Tobias; Rakhmatullina, Ekaterina; Bleek, Katrin; Boye, Susanne; Yuan, Jiayin; Völkel, Antje; Gräwert, Marlies; Cheaib, Zeinab; Eick, Sigrun; Günter, Christina; Lederer, Albena; Lussi, Adrian; Taubert, Andreas

    2014-11-10

    Poly(ethylene oxide) (PEO) has long been used as an additive in toothpaste, partly because it reduces biofilm formation on teeth. It does not, however, reduce the formation of dental calculus or support the remineralization of dental enamel or dentine. The present article describes the synthesis of new block copolymers on the basis of PEO and poly(3-sulfopropyl methacrylate) blocks using atom transfer radical polymerization. The polymers have very large molecular weights (over 10(6) g/mol) and are highly water-soluble. They delay the precipitation of calcium phosphate from aqueous solution but, upon precipitation, lead to relatively monodisperse hydroxyapatite (HAP) spheres. Moreover, the polymers inhibit the bacterial colonization of human enamel by Streptococcus gordonii, a pioneer bacterium in oral biofilm formation, in vitro. The formation of well-defined HAP spheres suggests that a polymer-induced liquid precursor phase could be involved in the precipitation process. Moreover, the inhibition of bacterial adhesion suggests that the polymers could be utilized in caries prevention.

  20. Water oxidation energy diagrams for photosystem II for different protonation states, and the effect of removing calcium.

    PubMed

    Siegbahn, Per E M

    2014-06-28

    The main parts of the water oxidation mechanism in photosystem II have now been established both from theory and experiments. Still, there are minor questions remaining. One of them concerns the charge and the protonation state of the oxygen evolving complex (OEC). Previously, theory and experiments have agreed that the two water derived ligands on the outer manganese should be one hydroxide and one water. In the present study it is investigated whether both of them could be water. This question is addressed by a detailed study of energy diagrams, but in this context it is more conclusive to compare the redox potential of the OEC to the one of TyrZ. Both procedures lead to the conclusion that one of the ligands is a hydroxide. Another question concerns the protonation of the second shell His337, where the results are more ambiguous. The final part of the present study describes results when calcium is removed from the OEC. Even though protons enter to compensate the charge of the missing Ca(2+), the redox potential and the pKa value of the OEC change dramatically and prevent the progress after S2.

  1. Indole-3-acetic acid-induced oxidative burst and an increase in cytosolic calcium ion concentration in rice suspension culture.

    PubMed

    Nguyen, Hieu T H; Umemura, Kenji; Kawano, Tomonori

    2016-08-01

    Indole-3-acetic acid (IAA) is the major natural auxin involved in the regulation of a variety of growth and developmental processes such as division, elongation, and polarity determination in growing plant cells. It has been shown that dividing and/or elongating plant cells accompanies the generation of reactive oxygen species (ROS) and a number of reports have suggested that hormonal actions can be mediated by ROS through ROS-mediated opening of ion channels. Here, we surveyed the link between the action of IAA, oxidative burst, and calcium channel activation in a transgenic cells of rice expressing aequorin in the cytosol. Application of IAA to the cells induced a rapid and transient generation of superoxide which was followed by a transient increase in cytosolic Ca(2+) concentration ([Ca(2+)]c). The IAA-induced [Ca(2+)]c elevation was inhibited by Ca(2+) channel blockers and a Ca(2+) chelator. Furthermore, ROS scavengers effectively blocked the action of IAA on [Ca(2+)]c elevation.

  2. One pot synthesis, structural and spectral analysis of some symmetrical curcumin analogues catalyzed by calcium oxide under microwave irradiation

    NASA Astrophysics Data System (ADS)

    Elavarasan, S.; Bhakiaraj, D.; Chellakili, B.; Elavarasan, T.; Gopalakrishnan, M.

    2012-11-01

    A series of sixteen number of curcumin analogues have been synthesized under microwave irradiation using calcium oxide as a catalyst. The synthesized compounds have been characterized using FT-IR, MS, elemental analysis, 1H and 13C NMR spectroscopic techniques. The UV-Vis absorption studies for these compounds have been studied in order to provide the electronic transitions taking place in the molecule. When compared to the curcumin ((1E,4Z,6E)-5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,4,6-trien-3-one), the absorption maxima, λmax for all the synthesized curcumin analogues with a variety of substituents gets blue shifted i.e., hypsochromic shift was observed. This shift may be assigned to the change of dipole moment within the solvated molecule. Theoretical calculations regarding the optimization of the synthesized molecules, electronic properties like highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and mapped electron density surface diagrams were done. The geometrical energy, dipole moments and heat of formation values have also been calculated using the ArgusLab package by AM1 semi-empirical method.

  3. Magnesia-stabilized calcium oxide absorbents with improved durability for high temperature CO{sub 2} capture

    SciTech Connect

    Li, L.Y.; King, D.L.; Nie, Z.M.; Howard, C.

    2009-12-15

    Calcium oxide based materials are attractive regenerable absorbents for separating CO{sub 2} from hot gas streams because of their high reactivity, high CO{sub 2} capacity, and low material cost. Their high carbonation temperature makes it possible to recover and use high quality heat released during CO{sub 2} capture, which increases overall process efficiency. However, the performance of all reported CaO-based absorbents deteriorates as the number of carbonation-decarbonation cycles increases. This is caused by absorbent sintering during the highly exothermic carbonation process. We have found that sintering can be effectively mitigated by properly mixing with a modest amount of MgO. A class of CaO-based absorbents with improved durability and CO{sub 2} reactivity were prepared by physical mixing of Ca(CH{sub 3}COO){sub 2} with small MgO particles followed by high temperature calcination. With 26 wt % MgO content, a CaO-MgO mixture prepared by this method gives as high as 53 wt % CO{sub 2} capacity after 50 carbonation-decarbonation cycles at 758{sup o}C. Without MgO addition, the CO{sub 2} capacity of pure CaO obtained from the same source decreases from 66 wt % for the first cycle to 26 wt % for the 50th cycle under the same test conditions.

  4. Water oxidation energy diagrams for photosystem II for different protonation states, and the effect of removing calcium.

    PubMed

    Siegbahn, Per E M

    2014-06-28

    The main parts of the water oxidation mechanism in photosystem II have now been established both from theory and experiments. Still, there are minor questions remaining. One of them concerns the charge and the protonation state of the oxygen evolving complex (OEC). Previously, theory and experiments have agreed that the two water derived ligands on the outer manganese should be one hydroxide and one water. In the present study it is investigated whether both of them could be water. This question is addressed by a detailed study of energy diagrams, but in this context it is more conclusive to compare the redox potential of the OEC to the one of TyrZ. Both procedures lead to the conclusion that one of the ligands is a hydroxide. Another question concerns the protonation of the second shell His337, where the results are more ambiguous. The final part of the present study describes results when calcium is removed from the OEC. Even though protons enter to compensate the charge of the missing Ca(2+), the redox potential and the pKa value of the OEC change dramatically and prevent the progress after S2. PMID:24618784

  5. Indole-3-acetic acid-induced oxidative burst and an increase in cytosolic calcium ion concentration in rice suspension culture.

    PubMed

    Nguyen, Hieu T H; Umemura, Kenji; Kawano, Tomonori

    2016-08-01

    Indole-3-acetic acid (IAA) is the major natural auxin involved in the regulation of a variety of growth and developmental processes such as division, elongation, and polarity determination in growing plant cells. It has been shown that dividing and/or elongating plant cells accompanies the generation of reactive oxygen species (ROS) and a number of reports have suggested that hormonal actions can be mediated by ROS through ROS-mediated opening of ion channels. Here, we surveyed the link between the action of IAA, oxidative burst, and calcium channel activation in a transgenic cells of rice expressing aequorin in the cytosol. Application of IAA to the cells induced a rapid and transient generation of superoxide which was followed by a transient increase in cytosolic Ca(2+) concentration ([Ca(2+)]c). The IAA-induced [Ca(2+)]c elevation was inhibited by Ca(2+) channel blockers and a Ca(2+) chelator. Furthermore, ROS scavengers effectively blocked the action of IAA on [Ca(2+)]c elevation. PMID:27149194

  6. A Raman Spectroscopic Study of the Structural Modifications Associated with the Addition of Calcium Oxide and Boron Oxide to Silica

    NASA Astrophysics Data System (ADS)

    Kline, Jeff; Tangstad, Merete; Tranell, Gabriella

    2015-02-01

    Raman spectroscopy as an instrumental technique for the determination of silicate structure is widely accepted. This method was utilized for analysis of structural modifications associated with the addition of network modifying species. Silicate melts are described by the extent of oxygen bridging. Therefore, understanding the effect different oxides have on modifying the silicate structure will provide valuable information regarding the removal of boron from silicon in slag refining processes. Samples in the range CaO/SiO2 = 0.56 to 1.2 were evaluated with and without varying concentrations of B2O3. As expected, increasing the CaO content resulted in an increase in the Q 0 and Q 1 species and a decrease in the Q 3 species indicating a depolymerization of the silicate network. The addition of B2O3 to the 36 wt pct CaO-64 wt pct SiO2 system resulted in a decrease in ring-typed structures associated with the vibrational mode near 600 cm-1, an increase in the Q 3 species and a decrease in the Q 2 species. Adding B2O3 to the 54.5 wt pct CaO-45.5 wt pct SiO2 system resulted in decrease in the Q 0 and Q 2 species and an increase in the Q 3 species. Thus, both systems indicate the introduction of B2O3 to the more polymerized structural units in the silicate network. The increase in the peak near 630 cm-1 signifies some formation of ring-type metaborate groups or ring-type danburite groups. A correlation between the experimentally determined Q n distribution and optical basicity is proposed. Viscosity and optical basicity are correlated for the CaO-SiO2 system as well as viscosity and.

  7. A Raman Spectroscopic Study of the Structural Modifications Associated with the Addition of Calcium Oxide and Boron Oxide to Silica

    NASA Astrophysics Data System (ADS)

    Kline, Jeff; Tangstad, Merete; Tranell, Gabriella

    2014-09-01

    Raman spectroscopy as an instrumental technique for the determination of silicate structure is widely accepted. This method was utilized for analysis of structural modifications associated with the addition of network modifying species. Silicate melts are described by the extent of oxygen bridging. Therefore, understanding the effect different oxides have on modifying the silicate structure will provide valuable information regarding the removal of boron from silicon in slag refining processes. Samples in the range CaO/SiO2 = 0.56 to 1.2 were evaluated with and without varying concentrations of B2O3. As expected, increasing the CaO content resulted in an increase in the Q 0 and Q 1 species and a decrease in the Q 3 species indicating a depolymerization of the silicate network. The addition of B2O3 to the 36 wt pct CaO-64 wt pct SiO2 system resulted in a decrease in ring-typed structures associated with the vibrational mode near 600 cm-1, an increase in the Q 3 species and a decrease in the Q 2 species. Adding B2O3 to the 54.5 wt pct CaO-45.5 wt pct SiO2 system resulted in decrease in the Q 0 and Q 2 species and an increase in the Q 3 species. Thus, both systems indicate the introduction of B2O3 to the more polymerized structural units in the silicate network. The increase in the peak near 630 cm-1 signifies some formation of ring-type metaborate groups or ring-type danburite groups. A correlation between the experimentally determined Q n distribution and optical basicity is proposed. Viscosity and optical basicity are correlated for the CaO-SiO2 system as well as viscosity and Q_{{exp}}^n.

  8. Corrosion resistance and calcium-phosphorus precipitation of micro-arc oxidized magnesium for biomedical applications

    NASA Astrophysics Data System (ADS)

    Zhao, Lichen; Cui, Chunxiang; Wang, Xin; Liu, Shuangjin; Bu, Shaojing; Wang, Qingzhou; Qi, Yumin

    2015-03-01

    To improve the corrosion resistance of magnesium, micro-arc oxidation (MAO) coatings were prepared on magnesium substrates in an aqueous solution with and without hydroxyapatite (HA) powders addition. The micrographs of scanning electron microscopy (SEM), the energy dispersive spectrometer (EDS) spectra, and X-ray diffraction (XRD) analysis show that the HA powders added into the electrolyte have participated in the formation reactions of MAO coating and the growth efficiency of MAO coating is greatly enhanced. Potentiodynamic polarization tests and immersion tests in simulated body fluid (SBF) confirm that the specimen anodized in the HA-containing electrolyte has a better corrosion resistance than the specimen anodized in the HA-free electrolyte. Immersion tests also indicate that the specimen anodized in the HA-containing electrolyte can more efficiently induce Ca-P precipitation compared with the specimen anodized in the HA-free electrolyte.

  9. [INDICES OF THE OXIDATIVE STATUS IN CHRONIC ADMINISTRATION OF COLLOID CARBONATE CALCIUM PRAPARATION WITH FAUCET AND LOW-MINERALIZED DRINKING WATER IN RATS].

    PubMed

    Khripach, L V; Mikhaylova, R I; Koganova, Z I; Knyazeva, T D; Alekseeva, A V; Savostikova, O N; Ryzhova, I N; Kruglova, E V; Revzova, T L

    2015-01-01

    There are discussed the changes of an array of indices of the oxidative status in chronic administration of colloidal calcium carbonate preparation with faucet and low-mineralized drinking water to rats. Slight differences between significant effects of administration of 3 and 30 mg/L of preparation permit to suggest that the process of its incoming delivery into organism of rats has a bottleneck in the nature of total capacity of macrophages of intestinal lymphoid tissue to absorption of particles. PMID:26856141

  10. DEGRADATION OF SM2ZR2O7 THERMAL BARRIER COATING CAUSED BY CALCIUM-MAGNESIUM-ALUMINUM-SILICON OXIDE (CMAS) DEPOSITION

    SciTech Connect

    Wang, Honglong; Sheng, Zhizhi; Tarwater, Emily; Zhang, Xingxing; Dasgupta, Sudip; Fergus, Jeffrey

    2015-03-16

    Rare earth zirconates are promising materials for use as thermal barrier coatings in gas turbine engines. Among the lanthanide zirconate materials, Sm2Zr2O7 with the pyrochlore structure has lower thermal conductivity and better corrosion resistance against calcium-magnesium-aluminum-silicon oxide (CMAS). In this work, after reaction with CMAS, the pyrochlore structure transforms to the cubic fluorite structure and Ca2Sm8(SiO4)6O2 forms in elongated grain.

  11. [INDICES OF THE OXIDATIVE STATUS IN CHRONIC ADMINISTRATION OF COLLOID CARBONATE CALCIUM PRAPARATION WITH FAUCET AND LOW-MINERALIZED DRINKING WATER IN RATS].

    PubMed

    Khripach, L V; Mikhaylova, R I; Koganova, Z I; Knyazeva, T D; Alekseeva, A V; Savostikova, O N; Ryzhova, I N; Kruglova, E V; Revzova, T L

    2015-01-01

    There are discussed the changes of an array of indices of the oxidative status in chronic administration of colloidal calcium carbonate preparation with faucet and low-mineralized drinking water to rats. Slight differences between significant effects of administration of 3 and 30 mg/L of preparation permit to suggest that the process of its incoming delivery into organism of rats has a bottleneck in the nature of total capacity of macrophages of intestinal lymphoid tissue to absorption of particles.

  12. Voltage-gated calcium channel currents in human coronary myocytes. Regulation by cyclic GMP and nitric oxide.

    PubMed Central

    Quignard, J F; Frapier, J M; Harricane, M C; Albat, B; Nargeot, J; Richard, S

    1997-01-01

    Voltage-gated Ca2+ channels contribute to the maintenance of contractile tone in vascular myocytes and are potential targets for vasodilating agents. There is no information available about their nature and regulation in human coronary arteries. We used the whole-cell voltage-clamp technique to characterize Ca2+-channel currents immediately after enzymatic dissociation and after primary culture of coronary myocytes taken from heart transplant patients. We recorded a dihydropyridine-sensitive L-type current in both freshly isolated and primary cultured cells. A T-type current was recorded only in culture. The L- (but not the T-) type current was inhibited by permeable analogues of cGMP in a dose-dependent manner. This effect was mimicked by the nitric oxide-generating agents S-nitroso-N-acetylpenicillamine (SNAP) and 3-morpholinosydnonimine which increased intracellular cGMP. Methylene blue, known to inhibit guanylate cyclase, antagonized the effect of SNAP. Inhibitions by SNAP and cGMP were not additive and seemed to occur through a common pathway. We conclude that (a) L-type Ca2+ channels are the major pathway for voltage-gated Ca2+ entry in human coronary myocytes; (b) their inhibition by agents stimulating nitric oxide and/or intracellular cGMP production is expected to contribute to vasorelaxation and may be involved in the therapeutic effect of nitrovasodilators; and (c) the expression of T-type Ca2+ channels in culture may be triggered by cell proliferation. PMID:9005986

  13. Particulate air pollution induces arrhythmia via oxidative stress and calcium calmodulin kinase II activation

    SciTech Connect

    Kim, Jin-Bae; Kim, Changsoo; Choi, Eunmi; Park, Sanghoon; Park, Hyelim; Pak, Hui-Nam; Lee, Moon-Hyoung; Shin, Dong Chun; Hwang, Ki-Chul; Joung, Boyoung

    2012-02-15

    Ambient particulate matter (PM) can increase the incidence of arrhythmia. However, the arrhythmogenic mechanism of PM is poorly understood. This study investigated the arrhythmogenic mechanism of PM. In Sprague–Dawley rats, QT interval was increased from 115.0 ± 14.0 to 142.1 ± 18.4 ms (p = 0.02) after endotracheal exposure of DEP (200 μg/ml for 30 min, n = 5). Ventricular premature contractions were more frequently observed after DEP exposure (100%) than baseline (20%, p = 0.04). These effects were prevented by pretreatment of N-acetylcysteine (NAC, 5 mmol/L, n = 3). In 12 Langendorff-perfused rat hearts, DEP infusion of 12.5 μg/ml for 20 min prolonged action potential duration (APD) at only left ventricular base increasing apicobasal repolarization gradients. Spontaneous early afterdepolarization (EAD) and ventricular tachycardia (VT) were observed in 8 (67%) and 6 (50%) hearts, respectively, versus no spontaneous triggered activity or VT in any hearts before DEP infusion. DEP-induced APD prolongation, EAD and VT were successfully prevented with NAC (5 mmol/L, n = 5), nifedipine (10 μmol/L, n = 5), and active Ca{sup 2+}/calmodulin-dependent protein kinase II (CaMKII) blockade, KN 93 (1 μmol/L, n = 5), but not by thapsigargin (200 nmol/L) plus ryanodine (10 μmol/L, n = 5) and inactive CaMKII blockade, KN 92 (1 μmol/L, n = 5). In neonatal rat cardiomyocytes, DEP provoked ROS generation in dose dependant manner. DEP (12.5 μg/ml) induced apoptosis, and this effect was prevented by NAC and KN 93. Thus, this study shows that in vivo and vitro exposure of PM induced APD prolongation, EAD and ventricular arrhythmia. These effects might be caused by oxidative stress and CaMKII activation. -- Highlights: ► The ambient PM consistently prolonged repolarization. ► The ambient PM induced triggered activity and ventricular arrhythmia. ► These effects were prevented by antioxidants, I{sub CaL} blockade and CaMKII blockade. ► The ambient PM can induce

  14. Biocorrosion resistance of coated magnesium alloy by microarc oxidation in electrolyte containing zirconium and calcium salts

    NASA Astrophysics Data System (ADS)

    Wang, Ya-Ming; Guo, Jun-Wei; Wu, Yun-Feng; Liu, Yan; Cao, Jian-Yun; Zhou, Yu; Jia, De-Chang

    2014-09-01

    The key to use magnesium alloys as suitable biodegradable implants is how to adjust their degradation rates. We report a strategy to prepare biocompatible ceramic coating with improved biocorrosion resistance property on AZ91D alloy by microarc oxidation (MAO) in a silicate-K2ZrF6 solution with and without Ca(H2PO4)2 additives. The microstructure and biocorrosion of coatings were characterized by XRD and SEM, as well as electrochemical and immersion tests in simulated body fluid (SBF). The results show that the coatings are mainly composed of MgO, Mg2SiO4, m-ZrO2 phases, further Ca containing compounds involve the coating by Ca(H2PO4)2 addition in the silicate-K2ZrF6 solution. The corrosion resistance of coated AZ91D alloy is significantly improved compared with the bare one. After immersing in SBF for 28 d, the Si-Zr5-Ca0 coating indicates a best corrosion resistance performance.

  15. Nitric oxide lowers the calcium sensitivity of tension in the rat tail artery

    PubMed Central

    Tran, Nguyen N P; Spitzbarth, Esther; Robert, Alain; Giummelly, Philippe; Atkinson, Jeffrey; Capdeville-Atkinson, Christine

    1998-01-01

    Controversy exists as to whether a fall in the intracellular Ca2+ concentration ([Ca2+]i) is a requisite element of the vasodilatory response to nitric oxide (NO). We studied the effect of NO on the coupling between [Ca2+]i and vasoconstriction in arterial segments loaded with the [Ca2+]i-sensitive, intracellular dye fura-2. As data interpretation is equivocal when fura-2 is loaded into both endothelial and smooth muscle cells, we compared results from in vitro experiments on segments of the rat tail artery in which fura-2 and noradrenaline were applied on the luminal or adventitial side, and endothelium was removed ‘physically’ (rubbing or air) or ‘functionally’ (Nω-nitro-l-arginine methyl ester). The use of air perfusion to remove endothelium is of considerable benefit since it allows paired observations in a single tissue. Fura-2 loaded into endothelial cells but endothelial ‘contamination’ of the smooth muscle cell [Ca2+]i signal was minimal. Endogenous NO decreased vasoconstrictor responses to noradrenaline but had no effect on [Ca2+]i. Nitroglycerine decreased vasoconstrictor responses in a concentration-dependent fashion but had no effect on [Ca2+]i. In conclusion, NO causes vasodilatation via a mechanism which is downstream of [Ca2+]i mobilization. PMID:9490833

  16. Surface Potential Control on Thin Oxide Films with Respect to Electron Stimulated Desorption Studies

    NASA Astrophysics Data System (ADS)

    Bernheim, Marc; Rousse, Gilles

    1995-09-01

    These experiments deal with the study of desorption of negative ions stimulated by low energy electron collisions on insulating surfaces covered with various adsorbates. For such investigation a careful control of the sample surface potential is required to set the incident electron energy accurately as well as to identify the desorbed species by mass spectrometry. Most of the reported experiments concern this surface potential control. We show that, for very thin SiO2 films thermally grown on silicon substrates, a tunnel conduction might set the surface potential accurately. This assertion mainly relies on recording the intensity of electrons transmitted through thin oxides as well as the intensity of backscattered and secondary electrons re-emitted from the surface. A direct comparison of the O^- ion energy distributions confirms the correct control of the surface potential for a large range of incident electron energies. In such condition we noticed that the O^- desorption yields just swiftly varied with incident electron energy. In particular no modification could be detected as the incident electron energy passed the various Auger excitation levels. The discrepancy between this last result and the published data is discussed in the last part of this paper. Des collisions électroniques sur des surfaces peuvent provoquer une éjection d'ions négatifs formés à partir des molécules adsorbées suivant un processus résonnant à très basse énergie. Pour étendre ces études expérimentales aux surfaces isolantes, un contrôle précis du potentiel superficiel devient indispensable tant pour fixer l'énergie finale des électrons sur la surface que pour effectuer la spectrométrie des ions désorbés. L'examen de surfaces de silice en couche mince montre comment une conduction tunnel intervient pour fixer le potentiel des surfaces examinées. Ces travaux expérimentaux effectués dans une configuration de miroir électrostatique reposent principalement sur l

  17. Mitoprotective antioxidant EUK-134 stimulates fatty acid oxidation and prevents hypertrophy in H9C2 cells.

    PubMed

    Purushothaman, Sreeja; Nair, R Renuka

    2016-09-01

    Oxidative stress is an important contributory factor for the development of cardiovascular diseases like hypertension-induced hypertrophy. Mitochondrion is the major source of reactive oxygen species. Hence, protecting mitochondria from oxidative damage can be an effective therapeutic strategy for the prevention of hypertensive heart disease. Conventional antioxidants are not likely to be cardioprotective, as they cannot protect mitochondria from oxidative damage. EUK-134 is a salen-manganese complex with superoxide dismutase and catalase activity. The possible role of EUK-134, a mitoprotective antioxidant, in the prevention of hypertrophy of H9C2 cells was examined. The cells were stimulated with phenylephrine (50 μM), and hypertrophy was assessed based on cell volume and expression of brain natriuretic peptide and calcineurin. Enhanced myocardial lipid peroxidation and protein carbonyl content, accompanied by nuclear factor-kappa B gene expression, confirmed the presence of oxidative stress in hypertrophic cells. Metabolic shift was evident from reduction in the expression of medium-chain acyl-CoA dehydrogenase. Mitochondrial oxidative stress was confirmed by the reduced expression of mitochondria-specific antioxidant peroxiredoxin-3 and enhanced mitochondrial superoxide production. Compromised mitochondrial function was apparent from reduced mitochondrial membrane potential. Pretreatment with EUK-134 (10 μM) was effective in the prevention of hypertrophic changes in H9C2 cells, reduction of oxidative stress, and prevention of metabolic shift. EUK-134 treatment improved the oxidative status of mitochondria and reversed hypertrophy-induced reduction of mitochondrial membrane potential. Supplementation with EUK-134 is therefore identified as a novel approach to attenuate cardiac hypertrophy and lends scope for the development of EUK-134 as a therapeutic agent in the management of human cardiovascular disease. PMID:27514538

  18. Palmitate induces ER calcium depletion and apoptosis in mouse podocytes subsequent to mitochondrial oxidative stress

    PubMed Central

    Xu, S; Nam, S M; Kim, J-H; Das, R; Choi, S-K; Nguyen, T T; Quan, X; Choi, S J; Chung, C H; Lee, E Y; Lee, I-K; Wiederkehr, A; Wollheim, C B; Cha, S-K; Park, K-S

    2015-01-01

    Pathologic alterations in podocytes lead to failure of an essential component of the glomerular filtration barrier and proteinuria in chronic kidney diseases. Elevated levels of saturated free fatty acid (FFA) are harmful to various tissues, implemented in the progression of diabetes and its complications such as proteinuria in diabetic nephropathy. Here, we investigated the molecular mechanism of palmitate cytotoxicity in cultured mouse podocytes. Incubation with palmitate dose-dependently increased cytosolic and mitochondrial reactive oxygen species, depolarized the mitochondrial membrane potential, impaired ATP synthesis and elicited apoptotic cell death. Palmitate not only evoked mitochondrial fragmentation but also caused marked dilation of the endoplasmic reticulum (ER). Consistently, palmitate upregulated ER stress proteins, oligomerized stromal interaction molecule 1 (STIM1) in the subplasmalemmal ER membrane, abolished the cyclopiazonic acid-induced cytosolic Ca2+ increase due to depletion of luminal ER Ca2+. Palmitate-induced ER Ca2+ depletion and cytotoxicity were blocked by a selective inhibitor of the fatty-acid transporter FAT/CD36. Loss of the ER Ca2+ pool induced by palmitate was reverted by the phospholipase C (PLC) inhibitor edelfosine. Palmitate-dependent activation of PLC was further demonstrated by following cytosolic translocation of the pleckstrin homology domain of PLC in palmitate-treated podocytes. An inhibitor of diacylglycerol (DAG) kinase, which elevates cytosolic DAG, strongly promoted ER Ca2+ depletion by low-dose palmitate. GF109203X, a PKC inhibitor, partially prevented palmitate-induced ER Ca2+ loss. Remarkably, the mitochondrial antioxidant mitoTEMPO inhibited palmitate-induced PLC activation, ER Ca2+ depletion and cytotoxicity. Palmitate elicited cytoskeletal changes in podocytes and increased albumin permeability, which was also blocked by mitoTEMPO. These data suggest that oxidative stress caused by saturated FFA leads to

  19. Hypergravity differentially modulates cGMP efflux in human melanocytic cells stimulated by nitric oxide and natriuretic peptides

    NASA Astrophysics Data System (ADS)

    Ivanova, K.; Stieber, C.; Lambers, B.; Block, I.; Krieg, R.; Wellmann, A.; Gerzer, R.

    Nitric oxide NO plays a key role in many patho physiologic processes including inflammation and skin cancer The diverse cellular effects of NO are mainly mediated by activation of the soluble guanylyl cyclase sGC isoform that leads to increases in intracellular cGMP levels whereas the membrane-bound isoforms serve as receptors for natriuretic peptides e g ANP In human skin epidermal melanocytes represent the principal cells for skin pigmentation by synthesizing the pigment melanin Melanin acts as a scavenger for free radicals that may arise during metabolic stress as a result of potentially harmful effects of the environment In previous studies we found that long-term exposure to hypergravity stimulated cGMP efflux in normal human melanocytes NHMs and non-metastatic melanoma cells at least partly by an enhanced expression of the multidrug resistance proteins MRP and cGMP transporters MRP4 5 The present study investigated whether hypergravity generated by centrifugal acceleration may modulate the cGMP efflux in NO-stimulated NHMs and melanoma cells MCs with different metastatic potential The NONOates PAPA-NO and DETA-NO were used as direct NO donors for cell stimulation In the presence of 0 1 mM DETA-NO t 1 2 sim 20 h long-term application of hypergravity up to 5 g for 24 h reduced intracellular cGMP levels by stimulating cGMP efflux in NHMs and non-metastatic MCs in comparison to 1 g whereas exposure to 5 g for 6 h in the presence of 0 1 mM PAPA-NO t 1 2 sim 30 min was not effective The hypergravity-stimulated

  20. Arginase inhibition reduces interleukin-1β-stimulated vascular smooth muscle cell proliferation by increasing nitric oxide synthase-dependent nitric oxide production

    SciTech Connect

    Yoon, Jeongyeon; Ryoo, Sungwoo

    2013-06-07

    Highlights: •Arginase inhibition suppressed proliferation of IL-1β-stimulated VSMCs in dose-dependent manner. •NO production from IL-1β-induced iNOS expression was augmented by arginase inhibition, reducing VSMC proliferation. •Incubation with cGMP analogues abolished IL-1β-dependent proliferation of VSMCs. -- Abstract: We investigated whether arginase inhibition suppressed interleukin (IL)-1β-stimulated proliferation in vascular smooth muscle cells (VSMCs) and the possible mechanisms involved. IL-1β stimulation increased VSMC proliferation, while the arginase inhibitor BEC and transfection of the antisense (AS) oligonucleotide against arginase I decreased VSMC proliferation and was associated with increased protein content of the cell cycle regulator p21Waf1/Cip1. IL-1β incubation induced inducible nitric oxide synthase (iNOS) mRNA expression and protein levels in a dose-dependent manner, but did not affect arginase I and II expression. Consistent with this data, IL-1β stimulation resulted in increase in NO production that was significantly augmented by arginase inhibition. The specific iNOS inhibitor 1400W abolished IL-1β-mediated NO production and further accentuated IL-1β-stimulated cell proliferation. Incubation with NO donors GSNO and DETA/NO in the presence of IL-1β abolished VSMCs proliferation and increased p21Waf1/Cip1 protein content. Furthermore, incubation with the cGMP analogue 8-Br-cGMP prevented IL-1β-induced VSMCs proliferation. In conclusion, arginase inhibition augmented iNOS-dependent NO production that resulted in suppression of IL-1β-induced VSMCs proliferation in a cGMP-dependent manner.

  1. Neuromuscular electrical stimulation and dietary interventions to reduce oxidative stress in a secondary progressive multiple sclerosis patient leads to marked gains in function: a case report.

    PubMed

    Reese, David; Shivapour, Ezzatolah T; Wahls, Terry L; Dudley-Javoroski, Shauna D; Shields, Richard

    2009-01-01

    Neuromuscular electrical stimulation has been used to aid musculoskeletal recovery. Excessive oxidative stress and excitoxicity are implicated in secondary progressive multiple sclerosis. A 52-year-old white female with SPMS had been scooter- and cane-dependent for 4 years. She requested and received a trial of neuromuscular electrical stimulation. Two months after initiating NMES the patient adopted several nutritional interventions to lower oxidative stress and excito-toxicity. During the first 2 months of neuromuscular electrical stimulation, the therapist observed modest gait improvements. Following the addition of nutritional interventions, more rapids gains in strength and endurance, including muscle groups not receiving neuromuscular electrical stimulation were observed by both the therapist and the patient. After 8 months of neuromuscular electrical stimulation (6 months of nutritional intervention) the patient's function had improved sufficiently that she no longer used a scooter or cane and rode her bicycle routinely 8 miles, including hills. PMID:19918474

  2. Neuromuscular electrical stimulation and dietary interventions to reduce oxidative stress in a secondary progressive multiple sclerosis patient leads to marked gains in function: a case report

    PubMed Central

    Reese, David; Shivapour, Ezzatolah T; Dudley-Javoroski, Shauna D; Shields, Richard

    2009-01-01

    Neuromuscular electrical stimulation has been used to aid musculoskeletal recovery. Excessive oxidative stress and excitoxicity are implicated in secondary progressive multiple sclerosis. A 52-year-old white female with SPMS had been scooter- and cane-dependent for 4 years. She requested and received a trial of neuromuscular electrical stimulation. Two months after initiating NMES the patient adopted several nutritional interventions to lower oxidative stress and excito-toxicity. During the first 2 months of neuromuscular electrical stimulation, the therapist observed modest gait improvements. Following the addition of nutritional interventions, more rapids gains in strength and endurance, including muscle groups not receiving neuromuscular electrical stimulation were observed by both the therapist and the patient. After 8 months of neuromuscular electrical stimulation (6 months of nutritional intervention) the patient’s function had improved sufficiently that she no longer used a scooter or cane and rode her bicycle routinely 8 miles, including hills. PMID:19918474

  3. Cardiac neuronal nitric oxide synthase isoform regulates myocardial contraction and calcium handling.

    PubMed

    Sears, Claire E; Bryant, Simon M; Ashley, Euan A; Lygate, Craig A; Rakovic, Stevan; Wallis, Helen L; Neubauer, Stefan; Terrar, Derek A; Casadei, B

    2003-03-21

    A neuronal isoform of nitric oxide synthase (nNOS) has recently been located to the cardiac sarcoplasmic reticulum (SR). Subcellular localization of a constitutive NOS in the proximity of an activating source of Ca2+ suggests that cardiac nNOS-derived NO may regulate contraction by exerting a highly specific and localized action on ion channels/transporters involved in Ca2+ cycling. To test this hypothesis, we have investigated myocardial Ca2+ handling and contractility in nNOS knockout mice (nNOS-/-) and in control mice (C) after acute nNOS inhibition with 100 micromol/L L-VNIO. nNOS gene disruption or L-VNIO increased basal contraction both in left ventricular (LV) myocytes (steady-state cell shortening 10.3+/-0.6% in nNOS-/- versus 8.1+/-0.5% in C; P<0.05) and in vivo (LV ejection fraction 53.5+/-2.7 in nNOS-/- versus 44.9+/-1.5% in C; P<0.05). nNOS disruption increased ICa density (in pA/pF, at 0 mV, -11.4+/-0.5 in nNOS-/- versus -9.1+/-0.5 in C; P<0.05) and prolonged the slow time constant of inactivation of ICa by 38% (P<0.05), leading to an increased Ca2+ influx and a greater SR load in nNOS-/- myocytes (in pC/pF, 0.78+/-0.04 in nNOS-/- versus 0.64+/-0.03 in C; P<0.05). Consistent with these data, [Ca2+]i transient (indo-1) peak amplitude was greater in nNOS-/- myocytes (410/495 ratio 0.34+/-0.01 in nNOS-/- versus 0.31+/-0.01 in C; P<0.05). These findings have uncovered a novel mechanism by which intracellular Ca2+ is regulated in LV myocytes and indicate that nNOS is an important determinant of basal contractility in the mammalian myocardium. The full text of this article is available at http://www.circresaha.org.

  4. Impact of oxidative stress on human cytomegalovirus replication and on cytokine-mediated stimulation of endothelial cells.

    PubMed

    Scholz, M; Cinatl, J; Gross, V; Vogel, J U; Blaheta, R A; Freisleben, H J; Markus, B H; Doerr, H W

    1996-06-27

    Transplantation-related pathogenic factors such as ischemia or allograft-directed inflammation are associated with oxidative changes that might lead to cellular oxidative stress. The aim of this study was to investigate the impact of oxidative stress on: (1) CMV replication in cultured human endothelial cells and (2) the stimulation of endothelial cells by proinfiammatory cytokines. Both pathomechanisms are known to contribute to graft rejection crises in vivo. Oxidative stress was induced in endothelial cell cultures with 10-200 microM buthionine sulfoximine. Western blotting showed a significant increase in the production of CMV-specific immediate early and late proteins in buthionine sulfoximine-treated cultures. Immunocytochemical staining suggested that this effect was caused by increased numbers of CMV antigen expressing cells (66% immediate early; 78%, late). Quantitative polymerase chain reaction for CMV-specific DNA and virus titration revealed that enhanced viral replication levels correlated with increased virion production. As a measure for the endothelial cell activation status, the surface expression of HLA-ABC and HLA-DR and adhesion molecules (ICAM-1, ELAM-1, VCAM-1) was quantified by fluorometric methods. Whereas oxidative stress alone did not modulate any surface molecule expression, the IFN-gamma-mediated expression of HLA-ABC and HLA-DR and the IL-1-mediated expression of ICAM-1, but not of ELAM-1 and VCAM-1 (IL-1 + TNF-alpha), was amplified. Interestingly, the amplification of HLA molecule expression was even higher in CMV-infected endothelial cells. This study provides evidence that oxidative stress contributes to the regulation of CMV replication, virus shedding, and the activation of endothelial cells by proinflammatory cytokines as it is observed in transplant recipients.

  5. AMBIENT PARTICULATE MATTER STIMULATES OXIDATIVE STRESS IN BRAIN MICROGLIA AND DAMAGES NEURONS IN CULTURE.

    EPA Science Inventory

    Ambient particulate matter (PM) damages biological targets through oxidative stress (OS) pathways. Several reports indicate that the brain is one of those targets. Since microglia (brain macrophage) are critical to OS-mediated neurodegeneration, their response to concentrated amb...

  6. Oxidized lipids activate autophagy in a JNK-dependent manner by stimulating the endoplasmic reticulum stress response.

    PubMed

    Haberzettl, Petra; Hill, Bradford G

    2013-01-01

    Excessive production of unsaturated aldehydes from oxidized lipoproteins and membrane lipids is a characteristic feature of cardiovascular disease. Our previous studies show that unsaturated lipid peroxidation-derived aldehydes such as 4-hydroxy-trans-2-nonenal (HNE) promote autophagy in rat aortic smooth muscle cells (RASMC). In this study, we examined the mechanism by which HNE induces autophagy. Exposure of RASMC to HNE led to the modification of several proteins, most of which were identified by mass spectrometry and confocal microscopy to be localized to the endoplasmic reticulum (ER). HNE stimulated the phosphorylation of PKR-like ER kinase and eukaryotic initiation factor 2α and increased heme oxygenase-1 (HO-1) abundance. HNE treatment also increased LC3-II formation and the phosphorylation of JNK and p38. Pharmacological inhibition of JNK, but not p38, prevented HNE-induced HO-1 expression and LC3-II formation. Inhibition of JNK increased cell death in HNE-treated cells. Pretreatment with the chemical chaperone phenylbutryic acid prevented LC3-II formation as well as JNK phosphorylation and HO-1 induction. Taken together, these data suggest that autophagic responses triggered by unsaturated aldehydes could be attributed, in part, to ER stress, which stimulates autophagy by a JNK-dependent mechanism and promotes cell survival during oxidative stress.

  7. Investigation of the effects of distance from sources on apoptosis, oxidative stress and cytosolic calcium accumulation via TRPV1 channels induced by mobile phones and Wi-Fi in breast cancer cells.

    PubMed

    Çiğ, Bilal; Nazıroğlu, Mustafa

    2015-10-01

    TRPV1 is a Ca2+ permeable channel and gated by noxious heat, oxidative stress and capsaicin (CAP). Some reports have indicated that non-ionized electromagnetic radiation (EMR)-induces heat and oxidative stress effects. We aimed to investigate the effects of distance from sources on calcium signaling, cytosolic ROS production, cell viability, apoptosis, plus caspase-3 and -9 values induced by mobile phones and Wi-Fi in breast cancer cells MCF-7 human breast cancer cell lines were divided into A, B, C and D groups as control, 900, 1800 and 2450 MHz groups, respectively. Cells in Group A were used as control and were kept in cell culture conditions without EMR exposure. Groups B, C and D were exposed to the EMR frequencies at different distances (0 cm, 1 cm, 5 cm, 10 cm, 20 cm and 25 cm) for 1h before CAP stimulation. The cytosolic ROS production, Ca2+ concentrations, apoptosis, caspase-3 and caspase-9 values were higher in groups B, C and D than in A group at 0 cm, 1 cm and 5 cm distances although cell viability (MTT) values were increased by the distances. There was no statistically significant difference in the values between control, 20 and 25 cm. Wi-Fi and mobile phone EMR placed within 10 cm of the cells induced excessive oxidative responses and apoptosis via TRPV1-induced cytosolic Ca2+ accumulation in the cancer cells. Using cell phones and Wi-Fi sources which are farther away than 10 cm may provide useful protection against oxidative stress, apoptosis and overload of intracellular Ca2+. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  8. Investigation of the effects of distance from sources on apoptosis, oxidative stress and cytosolic calcium accumulation via TRPV1 channels induced by mobile phones and Wi-Fi in breast cancer cells.

    PubMed

    Çiğ, Bilal; Nazıroğlu, Mustafa

    2015-10-01

    TRPV1 is a Ca2+ permeable channel and gated by noxious heat, oxidative stress and capsaicin (CAP). Some reports have indicated that non-ionized electromagnetic radiation (EMR)-induces heat and oxidative stress effects. We aimed to investigate the effects of distance from sources on calcium signaling, cytosolic ROS production, cell viability, apoptosis, plus caspase-3 and -9 values induced by mobile phones and Wi-Fi in breast cancer cells MCF-7 human breast cancer cell lines were divided into A, B, C and D groups as control, 900, 1800 and 2450 MHz groups, respectively. Cells in Group A were used as control and were kept in cell culture conditions without EMR exposure. Groups B, C and D were exposed to the EMR frequencies at different distances (0 cm, 1 cm, 5 cm, 10 cm, 20 cm and 25 cm) for 1h before CAP stimulation. The cytosolic ROS production, Ca2+ concentrations, apoptosis, caspase-3 and caspase-9 values were higher in groups B, C and D than in A group at 0 cm, 1 cm and 5 cm distances although cell viability (MTT) values were increased by the distances. There was no statistically significant difference in the values between control, 20 and 25 cm. Wi-Fi and mobile phone EMR placed within 10 cm of the cells induced excessive oxidative responses and apoptosis via TRPV1-induced cytosolic Ca2+ accumulation in the cancer cells. Using cell phones and Wi-Fi sources which are farther away than 10 cm may provide useful protection against oxidative stress, apoptosis and overload of intracellular Ca2+. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers. PMID:25703814

  9. Characterization of sputtered iridium oxide thin films on planar and laser micro-structured platinum thin film surfaces for neural stimulation applications

    NASA Astrophysics Data System (ADS)

    Thanawala, Sachin

    Electrical stimulation of neurons provides promising results for treatment of a number of diseases and for restoration of lost function. Clinical examples include retinal stimulation for treatment of blindness and cochlear implants for deafness and deep brain stimulation for treatment of Parkinsons disease. A wide variety of materials have been tested for fabrication of electrodes for neural stimulation applications, some of which are platinum and its alloys, titanium nitride, and iridium oxide. In this study iridium oxide thin films were sputtered onto laser micro-structured platinum thin films by pulsed-DC reactive sputtering of iridium metal in oxygen-containing atmosphere, to obtain high charge capacity coatings for neural stimulation applications. The micro-structuring of platinum films was achieved by a pulsed-laser-based technique (KrF excimer laser emitting at lambda=248nm). The surface morphology of the micro-structured films was studied using different surface characterization techniques. In-vitro biocompatibility of these laser micro-structured films coated with iridium oxide thin films was evaluated using cortical neurons isolated from rat embryo brain. Characterization of these laser micro-structured films coated with iridium oxide, by cyclic voltammetry and impedance spectroscopy has revealed a considerable decrease in impedance and increase in charge capacity. A comparison between amorphous and crystalline iridium oxide thin films as electrode materials indicated that amorphous iridium oxide has significantly higher charge capacity and lower impedance making it preferable material for neural stimulation application. Our biocompatibility studies show that neural cells can grow and differentiate successfully on our laser micro-structured films coated with iridium oxide. This indicates that reactively sputtered iridium oxide (SIROF) is biocompatible.

  10. Exposure to nitrous oxide stimulates a nitric oxide-dependent neuronal release of beta-endorphin in ventricular-cisternally-perfused rats.

    PubMed

    Zelinski, Lisa M; Ohgami, Yusuke; Quock, Raymond M

    2009-12-01

    We have previously shown that the antinociceptive effect of nitrous oxide (N(2)O) in the rat hot plate test is sensitive to antagonism by antisera against the endogenous opioid peptide beta-endorphin. Moreover, N(2)O-induced antinociception is reduced by inhibition of nitric oxide (NO) production in the brain. To test the hypothesis that N(2)O might stimulate an NO-dependent neuronal release of beta-endorphin, we conducted a ventricular-cisternal perfusion with artificial cerebrospinal fluid (aCSF) in urethane-anesthetized Sprague-Dawley rats. Ten-minute fractions of aCSF perfusate were collected from separate groups of room air-exposed rats, N(2)O-exposed rats, and L-NAME-pretreated, N(2)O-exposed rats; they were then analyzed for their content of NO metabolites and beta-endorphin. Compared to room air control, exposure to 70% N(2)O increased perfusate levels of the NO metabolites nitrite and nitrate as well as beta-endorphin. Pretreatment of rats with L-N(G)-nitro arginine methyl ester, an inhibitor of NO synthase, prevented the N(2)O-induced increases in nitrite, nitrate and beta-endorphin. These findings demonstrate in an in vivo rat model that N(2)O may stimulate an NO-dependent neuronal release of beta-endorphin. PMID:19747467

  11. Pterostilbene, an Active Constituent of Blueberries, Stimulates Nitric Oxide Production via Activation of Endothelial Nitric Oxide Synthase in Human Umbilical Vein Endothelial Cells.

    PubMed

    Park, Seong Hoon; Jeong, Sun-Oh; Chung, Hun-Teag; Pae, Hyun-Ock

    2015-09-01

    Endothelial dysfunction, a key process in development of cardiovascular diseases, is largely due to reduced nitric oxide (NO) derived from endothelial NO synthase (eNOS). Resveratrol has been reported to stimulate NO production via estrogen receptor α (ERα) activation in endothelial cells. Here, we investigated whether two natural methylated analogs of resveratrol, pterostilbene (Pts) and trans-3,5,4'-trimethoxystilbene (TMS), similarly to resveratrol, could influence endothelial NO release in human umbilical vein endothelial cells (HUVECs). In HUVECs exposed to Pts or TMS, NO production and phosphorylation of eNOS, protein kinase B (Akt), and ERα were measured by using a fluorimetric NO assay kit and Western blot analysis, respectively. Dimethylated Pts, but not trimethylated TMS, stimulated dose-dependent NO production via eNOS phosphorylation. Pts also stimulated dose-dependent phosphorylation of Akt, but not of ERα. NO production and eNOS phosphorylation in response to Pts were significantly abolished by the phosphoinositide 3-kinase (PI3K)/Akt inhibitor LY294002, but not by the ERα antagonist ICI182780. Our results suggest that Pts, but not TMS, is capable of inducing eNOS phosphorylation and the subsequent NO release, presumably, by activating PI3K/Akt pathway. The potential efficacy of Pts, an active constituent of blueberries, may aid in the prevention of cardiovascular diseases characterized by endothelial dysfunction.

  12. Myeloperoxidase Stimulates Neutrophil Degranulation.

    PubMed

    Grigorieva, D V; Gorudko, I V; Sokolov, A V; Kostevich, V A; Vasilyev, V B; Cherenkevich, S N; Panasenko, O M

    2016-08-01

    Myeloperoxidase, heme enzyme of azurophilic granules in neutrophils, is released into the extracellular space in the inflammation foci. In neutrophils, it stimulates a dose-dependent release of lactoferrin (a protein of specific granules), lysozyme (a protein of specific and azurophilic granules), and elastase (a protein of azurophilic granules). 4-Aminobenzoic acid hydrazide, a potent inhibitor of peroxidase activity of myeloperoxidase, produced no effect on neutrophil degranulation. Using signal transduction inhibitors (genistein, methoxyverapamil, wortmannin, and NiCl2), we demonstrated that myeloperoxidase-induced degranulation of neutrophils resulted from enzyme interaction with the plasma membrane and depends on activation of tyrosine kinases, phosphatidylinositol 3-kinases (PI3K), and calcium signaling. Myeloperoxidase modified by oxidative/halogenation stress (chlorinated and monomeric forms of the enzyme) lost the potency to activate neutrophil degranulation. PMID:27597056

  13. Differential role of nitric oxide in regional sympathetic responses to stimulation of NTS A2a adenosine receptors.

    PubMed

    Scislo, Tadeusz J; Tan, Nobusuke; O'Leary, Donal S

    2005-02-01

    Our previous studies showed that preganglionic adrenal (pre-ASNA), renal (RSNA), lumbar, and postganglionic adrenal sympathetic nerve activities (post-ASNA) are inhibited after stimulation of arterial baroreceptors, nucleus of the solitary tract (NTS), and glutamatergic and P2x receptors and are activated after stimulation of adenosine A1 receptors. However, stimulation of adenosine A2a receptors inhibited RSNA and post-ASNA, whereas it activated pre-ASNA. Because the effects evoked by NTS A2a receptors may be mediated via activation of nitric oxide (NO) mechanisms in NTS neurons, we tested the hypothesis that NO synthase (NOS) inhibitors would attenuate regional sympathetic responses to NTS A2a receptor stimulation, whereas NO donors would evoke contrasting responses from pre-ASNA versus RSNA and post-ASNA. Therefore, in chloralose/urethane-anesthetized rats, we compared hemodynamic and regional sympathetic responses to microinjections of selective A2a receptor agonist (CGS-21680, 20 pmol/50 nl) after pretreatment with NOS inhibitors Nomega-nitro-L-arginine methyl ester (10 nmol/100 nl) and 1-[2-(trifluoromethyl)phenyl]imidazole (100 pmol/100 nl) versus pretreatment with vehicle (100 nl). In addition, responses to microinjections into the NTS of different NO donors [40 and 400 pmol/50 nl sodium nitroprusside (SNP); 0.5 and 5 nmol/50 nl 3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene (DETA NONOate, also known as NOC-18), and 2 nmol/50 nl 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (PAPA NONOate, also known as NOC-15)], the NO precursor L-arginine (10-50 nmol/50 nl), and sodium glutamate (500 pmol/50 nl) were evaluated. SNP, DETA NONOate, and PAPA NONOate activated pre-ASNA and inhibited RSNA and post-ASNA, whereas l-arginine and glutamate microinjected into the same site of the NTS inhibited all these sympathetic outputs. Decreases in heart rate and depressor or biphasic responses accompanied the neural responses. Pretreatment with NOS inhibitors

  14. Nickel-Cobalt Oxide Decorated Three-Dimensional Graphene as an Enzyme Mimic for Glucose and Calcium Detection.

    PubMed

    Wu, Meiyan; Meng, Shangjun; Wang, Qian; Si, Weili; Huang, Wei; Dong, Xiaochen

    2015-09-30

    Glucose and calcium ion play key roles in human bodies. The needlelike NiCo2O4 nanostructures are in situ deposited on three-dimensional graphene foam (3DGF) by a facile hydrothermal procedure. The structure and morphology of the hierarchical NiCo2O4/3DGF are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. With the self-standing NiCo2O4/3DGF as electrochemical electrode, it can realize the high-sensitivity detections for glucose and calcium ion. The limit of detection can reach 0.38 and 4.45 μM, respectively. In addition, the electrochemical electrode presents excellent selectivity for glucose and calcium ion. This study demonstrates that NiCo2O4/3DGF is a unique and promising material for practical application in both glucose and calcium ion sensing. PMID:26329273

  15. Nickel-Cobalt Oxide Decorated Three-Dimensional Graphene as an Enzyme Mimic for Glucose and Calcium Detection.

    PubMed

    Wu, Meiyan; Meng, Shangjun; Wang, Qian; Si, Weili; Huang, Wei; Dong, Xiaochen

    2015-09-30

    Glucose and calcium ion play key roles in human bodies. The needlelike NiCo2O4 nanostructures are in situ deposited on three-dimensional graphene foam (3DGF) by a facile hydrothermal procedure. The structure and morphology of the hierarchical NiCo2O4/3DGF are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. With the self-standing NiCo2O4/3DGF as electrochemical electrode, it can realize the high-sensitivity detections for glucose and calcium ion. The limit of detection can reach 0.38 and 4.45 μM, respectively. In addition, the electrochemical electrode presents excellent selectivity for glucose and calcium ion. This study demonstrates that NiCo2O4/3DGF is a unique and promising material for practical application in both glucose and calcium ion sensing.

  16. Generation of oxidant response to copper and iron nanoparticles and salts: Stimulation by ascorbate

    PubMed Central

    Rice, Robert H.; Vidrio, Edgar A.; Kumfer, Benjamin M.; Qin, Qin; Willits, Neil H.; Kennedy, Ian M.; Anastasio, Cort

    2009-01-01

    The present work describes a two-stage approach to analyzing combustion-generated samples for their potential to produce oxidant stress. This approach is illustrated with the two commonly encountered transition metals, copper and iron. First, their abilities to generate hydroxyl radical were measured in a cell-free, phosphate-buffered saline solution containing ascorbate and/or citrate. Second, their abilities to induce heme oxygenase-1 in cultured human epidermal keratinocytes were assessed in cell culture. Combustion-generated copper oxide nanoparticles were active in both assays and were found to be soluble in culture medium. Depletion of glutathione in the cells or loading the cells with ascorbate greatly increased heme oxygenase-1 induction in the presence of copper. By contrast, iron oxide nanoparticles were active in the phosphate buffered saline but not in cell culture, and they aggregated in culture medium. Soluble salts of copper and iron exhibited the same contrast in activities as the respective combustion-generated particles. The results suggest that the capability of combustion-generated environmental samples to produce oxidant stress can be screened effectively in a two step process, first in phosphate buffered saline with ascorbate and subsequently in epithelial cell culture for those exhibiting activity initially. The results also point to an unanticipated interaction in cells of oxidant stress-generating metals with an anti-oxidant (ascorbate) that is usually missing in culture medium formulations. Thus, ascorbate supplementation of cultured human cells is likely to improve their ability to model the in vivo effects of particulate matter containing copper and other redox-active metals. PMID:19683516

  17. Calcium Carbonate

    MedlinePlus

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  18. Calcium - urine

    MedlinePlus

    High levels of urine calcium (above 300 mg/day) may be due to: Chronic kidney disease High vitamin D levels Leaking of calcium from the kidneys into the urine, which causes calcium kidney stones Sarcoidosis Taking ...

  19. Bicyclic monoterpene diols stimulate release of nitric oxide from skin cells, increase microcirculation, and elevate skin temperature.

    PubMed

    Brown, David A; Canning, Matthew T; Nay, Stephanie L; Pena, Arely V; Yarosh, Daniel B

    2006-08-01

    Bicyclic monoterpene diols (BMTd) stimulate nitric oxide synthesis in melanoma and neuronal cells, representing cell types arising from embryonic neural crest tissue. This study shows that an equimolar mixture of the BMTd's 2,3-cis/exo-pinanediol and 2,3-cis/exo-camphanediol stimulates nitric oxide synthesis in epithelial cells of the skin, specifically normal human epidermal keratinocytes (NHEK) and normal human microvascular endothelial cells (HMVEC). A 1 mM mixture increased nitric oxide 3-fold in HMVEC in the first 24 h after treatment, and a 2 mM mixture produced an equivalent increase in NHEK. We hypothesized that an increase in nitric oxide in skin would lead to an increase in microcirculation, thereby increasing skin temperature. We found that twice daily application of 1mM BMTd lotion significantly increased arm skin temperature by 0.5 degrees C in 14 days compared to placebo, while a 2 mM mixture significantly increased skin temperature by 0.3 degrees C in 7 days (P < or = 0.05; ANOVA). A single application of a 2 mM BMTd mixture applied 30 min before a 30 min cold challenge (6 degrees C), maintained facial skin temperature 1.4 degrees C above untreated control sites (P < or = 0.05; ANOVA). We also tested whether BMTd treatment would benefit people with dark circles under their eyes. Twenty-six panelists with dark undereye circles completed 2-week, twice daily application of a lotion containing the 1mM mixture to one eye while the other eye was untreated. Seven of 26 subjects showed a reduction of darkness of undereye circles (P < or = 0.05; paired t test). Application of 2 mM BMTd lotion to lips resulted in a significant increase in their redness, as measured by the erythema index (P < or = 0.05; ANOVA). These results show that a mixture of BMTd's increases nitric oxide, and application to skin increases microcirculation and skin temperature.

  20. Comparison of soluble guanylate cyclase stimulators and activators in models of cardiovascular disease associated with oxidative stress.

    PubMed

    Costell, Melissa H; Ancellin, Nicolas; Bernard, Roberta E; Zhao, Shufang; Upson, John J; Morgan, Lisa A; Maniscalco, Kristeen; Olzinski, Alan R; Ballard, Victoria L T; Herry, Kenny; Grondin, Pascal; Dodic, Nerina; Mirguet, Olivier; Bouillot, Anne; Gellibert, Francoise; Coatney, Robert W; Lepore, John J; Jucker, Beat M; Jolivette, Larry J; Willette, Robert N; Schnackenberg, Christine G; Behm, David J

    2012-01-01

    Soluble guanylate cyclase (sGC), the primary mediator of nitric oxide (NO) bioactivity, exists as reduced (NO-sensitive) and oxidized (NO-insensitive) forms. We tested the hypothesis that the cardiovascular protective effects of NO-insensitive sGC activation would be potentiated under conditions of oxidative stress compared to those of NO-sensitive sGC stimulation. The cardiovascular effects of the NO-insensitive sGC activator GSK2181236A [a low, non-depressor dose, and a high dose which lowered mean arterial pressure (MAP) by 5-10 mmHg] and those of equi-efficacious doses of the NO-sensitive sGC stimulator BAY 60-4552 were assessed in (1) Sprague Dawley rats during coronary artery ischemia/reperfusion (I/R) and (2) spontaneously hypertensive stroke prone rats (SHR-SP) on a high salt/fat diet (HSFD). In I/R, neither compound reduced infarct size 24 h after reperfusion. In SHR-SP, HSFD increased MAP, urine output, microalbuminuria, and mortality, caused left ventricular hypertrophy with preserved ejection fraction, and impaired endothelium-dependent vasorelaxation. The low dose of BAY 60-4552, but not that of GSK2181236A, decreased urine output, and improved survival. Conversely, the low dose of GSK2181236A, but not that of BAY 60-4552, attenuated the development of cardiac hypertrophy. The high doses of both compounds similarly attenuated cardiac hypertrophy and improved survival. In addition to these effects, the high dose of BAY 60-4552 reduced urine output and microalbuminuria and attenuated the increase in MAP to a greater extent than did GSK2181236A. Neither compound improved endothelium-dependent vasorelaxation. In SHR-SP isolated aorta, the vasodilatory responses to the NO-dependent compounds carbachol and sodium nitroprusside were attenuated by HSFD. In contrast, the vasodilatory responses to both GSK2181236A and BAY 60-4552 were unaltered by HSFD, indicating that reduced NO-bioavailability and not changes in the oxidative state of sGC is responsible

  1. Comparison of Soluble Guanylate Cyclase Stimulators and Activators in Models of Cardiovascular Disease Associated with Oxidative Stress

    PubMed Central

    Costell, Melissa H.; Ancellin, Nicolas; Bernard, Roberta E.; Zhao, Shufang; Upson, John J.; Morgan, Lisa A.; Maniscalco, Kristeen; Olzinski, Alan R.; Ballard, Victoria L. T.; Herry, Kenny; Grondin, Pascal; Dodic, Nerina; Mirguet, Olivier; Bouillot, Anne; Gellibert, Francoise; Coatney, Robert W.; Lepore, John J.; Jucker, Beat M.; Jolivette, Larry J.; Willette, Robert N.; Schnackenberg, Christine G.; Behm, David J.

    2012-01-01

    Soluble guanylate cyclase (sGC), the primary mediator of nitric oxide (NO) bioactivity, exists as reduced (NO-sensitive) and oxidized (NO-insensitive) forms. We tested the hypothesis that the cardiovascular protective effects of NO-insensitive sGC activation would be potentiated under conditions of oxidative stress compared to those of NO-sensitive sGC stimulation. The cardiovascular effects of the NO-insensitive sGC activator GSK2181236A [a low, non-depressor dose, and a high dose which lowered mean arterial pressure (MAP) by 5–10 mmHg] and those of equi-efficacious doses of the NO-sensitive sGC stimulator BAY 60-4552 were assessed in (1) Sprague Dawley rats during coronary artery ischemia/reperfusion (I/R) and (2) spontaneously hypertensive stroke prone rats (SHR-SP) on a high salt/fat diet (HSFD). In I/R, neither compound reduced infarct size 24 h after reperfusion. In SHR-SP, HSFD increased MAP, urine output, microalbuminuria, and mortality, caused left ventricular hypertrophy with preserved ejection fraction, and impaired endothelium-dependent vasorelaxation. The low dose of BAY 60-4552, but not that of GSK2181236A, decreased urine output, and improved survival. Conversely, the low dose of GSK2181236A, but not that of BAY 60-4552, attenuated the development of cardiac hypertrophy. The high doses of both compounds similarly attenuated cardiac hypertrophy and improved survival. In addition to these effects, the high dose of BAY 60-4552 reduced urine output and microalbuminuria and attenuated the increase in MAP to a greater extent than did GSK2181236A. Neither compound improved endothelium-dependent vasorelaxation. In SHR-SP isolated aorta, the vasodilatory responses to the NO-dependent compounds carbachol and sodium nitroprusside were attenuated by HSFD. In contrast, the vasodilatory responses to both GSK2181236A and BAY 60-4552 were unaltered by HSFD, indicating that reduced NO-bioavailability and not changes in the oxidative state of sGC is responsible

  2. Eriobotrya japonica counteracts reactive oxygen species and nitric oxide stimulated by chloramphenicol.

    PubMed

    Eraso, Alberto Jorge; Albesa, Inés

    2007-01-01

    Chloramphenicol is a toxic antibiotic used for certain infections, though aplastic anaemia is one of its side-effects. The results of our experiments showed that blood cells suffered oxidative stress in the presence of chloramphenicol, with a significant increase in reactive oxygen species (ROS) detected by luminol-chemiluminescence (CL). The extract of fruits of Eriobotrya japonica markedly decreased ROS in leukocytes and erythrocytes, the oxidative stress caused by this antibiotic. Nitro Blue Tetrazolium (NBT) assay with purified leukocytes demonstrated that the antioxidant action of E. japonica caused an intracellular reduction in ROS, and that the extracts decreased these promoters of oxidative stress to normal levels in the cytoplasm. Determinations of nitric oxide (NO) generation indicated that E. japonica extracts also inhibited the stimuli of NO provoked by chloramphenicol. This study showed that the immediate antioxidant effect of E. japonica could be associated with the action of vitamin A. The protective action of this fruit was seen on mature leukocytes and erythrocytes, beneficial effect on blood cells suggest that its extract could be used as an antioxidant agent complementing the administration of chloramphenicol, as a modern-day extension to its traditional use in Chinese medicine.

  3. Environmental stimulation influence the cognition of developing mice by inducing changes in oxidative and apoptosis status.

    PubMed

    Cheng, Liang; Wang, Shao-Hui; Jia, Nan; Xie, Min; Liao, Xiao-Mei

    2014-01-01

    Environment condition has been shown to play an important role in brain development. The present study examined the effects of enriched and impoverished environment on both spatial and emotional learning and memory of young mice and explored the underlying mechanisms. 3-week-old mice were housed in enriched environment (n=10, 10 mice in a large cage with toys and a running wheel), or standard environment (n=10, 10 mice in a large cage without objects), or impoverished environment (n=10, single mice in a small cage without objects) for 6weeks. Then, the spatial and emotional cognition of mice were evaluated by the water maze and step-down inhibitory avoidance test, respectively. To explore the underlying mechanisms, oxidation measurement in hippocampus and medial-temporal lobe cortex (MTLC) and apoptosis examination in hippocampus were performed. Results showed that compared with standard environment group, enriched and impoverished mice exhibited high and low performance levels in behavior tests, respectively. The oxidative status of hippocampus and MTLC were decreased in enriched group but increased in impoverished group. Moreover, changes in apoptosis of hippocampus in these two groups showed the same tendency with oxidative status. These results suggest that environment condition can simultaneously influence spatial and emotional learning and memory, which may result from inducing changes in the oxidative and apoptosis status in associated brain regions. Here, we firstly report using young mice to examine the oxidative status as a primary and direct factor to explore the mechanism of effects of different environment on both spatial and emotional cognition. PMID:23273784

  4. Antinociceptive Effect of Vardenafil on Carrageenan-Induced Hyperalgesia in Rat: involvement of Nitric Oxide/Cyclic Guanosine Monophosphate/Calcium Channels Pathway

    PubMed Central

    Gediz, Ezgi İkiz; Nacitarhan, Cahit; Minareci, Edibe; Sadan, Gulay

    2015-01-01

    In this study, we aimed to investigate the peripheral antinociception effects of specific phosphodiesterase 5 (PDE-5) inhibitor vardenafil on carrageenan-induced nociception in rats, and the role of calcium besides the L-arginine- nitric oxide (NO)- cyclic guanosine monophophate (cGMP) pathway in these effects. Hyperalgesia was induced by the intraplantar injection of 0.1 mL fresh carrageenan solution to right hind-paw whereas, saline as a vehicle of carrageenan was injected to the left paw. This procedure was used for measuring mechanic nociception pressure via an analgesimeter. Pressure which produced nociception was measured before (0 minute) and after(15, 30, 60 and 120 minutes) carrageenan injection. Local administration of vardenafil produced a dose-dependent antinociceptive effect. Pretreatment with NW-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor), oxadiazolo (4, 3, a) quinoxalin -1-one (ODQ, inhibitor of guanylyl cyclase) or A23187 (calcium ionophore) decreased the effect of vardenafil. In contrast, L-arginine (nitric oxide donor) seemed to potentiate the vardenafil-induced antinociception. Our results suggest that phosphodiesterase type-5 inhibitor vardenafil may offer a new therapeutic tool to treat pain. It’s effect was probably result from L-arginine/NO-cGMP pathway activation and Ca + 2 channels are also involved. PMID:26664380

  5. Antinociceptive Effect of Vardenafil on Carrageenan-Induced Hyperalgesia in Rat: involvement of Nitric Oxide/Cyclic Guanosine Monophosphate/Calcium Channels Pathway.

    PubMed

    Gediz, Ezgi İkiz; Nacitarhan, Cahit; Minareci, Edibe; Sadan, Gulay

    2015-01-01

    In this study, we aimed to investigate the peripheral antinociception effects of specific phosphodiesterase 5 (PDE-5) inhibitor vardenafil on carrageenan-induced nociception in rats, and the role of calcium besides the L-arginine- nitric oxide (NO)- cyclic guanosine monophophate (cGMP) pathway in these effects. Hyperalgesia was induced by the intraplantar injection of 0.1 mL fresh carrageenan solution to right hind-paw whereas, saline as a vehicle of carrageenan was injected to the left paw. This procedure was used for measuring mechanic nociception pressure via an analgesimeter. Pressure which produced nociception was measured before (0 minute) and after(15, 30, 60 and 120 minutes) carrageenan injection. Local administration of vardenafil produced a dose-dependent antinociceptive effect. Pretreatment with N(W)-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor), oxadiazolo (4, 3, a) quinoxalin -1-one (ODQ, inhibitor of guanylyl cyclase) or A23187 (calcium ionophore) decreased the effect of vardenafil. In contrast, L-arginine (nitric oxide donor) seemed to potentiate the vardenafil-induced antinociception. Our results suggest that phosphodiesterase type-5 inhibitor vardenafil may offer a new therapeutic tool to treat pain. It's effect was probably result from L-arginine/NO-cGMP pathway activation and Ca + 2 channels are also involved. PMID:26664380

  6. The bulk composition and leaching properties of electroplating sludge prior/following the solidification/stabilization by calcium oxide.

    PubMed

    Orescanin, Visnja; Mikulic, Nenad; Mikelic, Ivanka Lovrencic; Posedi, Mario; Kampic, Stefica; Medunic, Gordana

    2009-10-01

    Eighteen samples of electroplating sludge were taken from three vertical profiles of waste storage pond of the zinc plating facility. Dry matter and organic matter content, pH value, bulk concentrations and leachate composition were determined. A sludge sample with the highest zinc value in the leachate was treated with calcium oxide (10% to 70%) and the obtained solidificate was repeatedly tested. There were found significant variations of all measured parameters among the profiles of untreated waste. Dry matter content varied from 125 to 455 mgg(-1), organic matter varied from 94.3 to 293.9 mgg(-1), and pH value varied from 3.42 to 5.90 (mean 4.34). Iron content ranged from 38.4 to 191.4 mgg(-1) (mean 136 mgg(-1); RSD 0.25), while zinc ranged from 10.9 to 58.2 mgg(-1) (mean 33.4 mgg(-1); RSD 0.38). According to its DIN38414-S4 leachate composition, this material was not suitable for landfilling of inert waste since zinc and nickel mean values were 10 and 1.5 times higher, respectively, and maximum values 27 and 2.5 times higher, respectively, compared to the upper permissible limit. Maximum values of Cr(VI), Fe, Ni, Cu, and Zn in the DIN38414-S4 leachate were 0.183 mgL(-1), 34.085 mgL(-1), 1.052 mgL(-1), 0.829 mgL(-1) and 107.475 mgL(-1)L, respectively. Following the solidification/stabilization procedure with CaO (sample/CaO = 90/10), concentrations of Cr(VI), Fe, Cu and Zn were reduced 92, 44, 66 and 57 times, respectively, compared to the untreated sample. The addition of 50% of CaO into the sludge reduced zinc and nickel concentrations 79 and 45 times, respectively, in the DIN38414-S4 leachate of the solidified waste compared to the original sludge, thereby converting an hazardous waste into the inert material suitable for landfilling or reuse in the construction processes.

  7. Focal physiological uncoupling of cerebral blood flow and oxidative metabolism during somatosensory stimulation in human subjects

    SciTech Connect

    Fox, P.T.; Raichle, M.E.

    1986-02-01

    Coupling between cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) was studied using multiple sequential administrations of VO-labeled radiotracers and positron emission tomography. In the resting state an excellent correlation between CBF and CMRO2 was found when paired measurements of CBF and CMRO2 from multiple (30-48) brain regions were tested in each of 33 normal subjects. Regional uncoupling of CBF and CMRO2 was found, however, during neuronal activation induced by somatosensory stimulation. Stimulus-induced focal augmentation of cerebral blood flow (29% mean) far exceeded the concomitant local increase in tissue metabolic rate (mean, 5%), when resting-state and stimulated-state measurements were obtained in each of 9 subjects. Stimulus duration had no significant effect on response magnitude or on the degree of CBF-CMRO2 uncoupling observed. Dynamic, physiological regulation of CBF by a mechanism (neuronal or biochemical) dependent on neuronal firing per se, but independent of the cerebral metabolic rate of oxygen, is hypothesized.

  8. Oxidative stress impairs multiple regulatory events to drive persistent cytokine-stimulated STAT3 phosphorylation.

    PubMed

    Ng, Ivan H W; Yeap, Yvonne Y C; Ong, Lynette S R; Jans, David A; Bogoyevitch, Marie A

    2014-03-01

    Although cytokine-driven STAT3 phosphorylation and activation are often transient, persistent activation of STAT3 is a hallmark of a range of pathologies and underpins altered transcriptional responses. As triggers in disease frequently include combined increases in inflammatory cytokine and reactive oxygen species levels, we report here how oxidative stress impacts on cytokine-driven STAT3 signal transduction events. In the model system of murine embryonic fibroblasts (MEFs), combined treatment with the interleukin-6 family cytokine Leukemia Inhibitory Factor (LIF) and hydrogen peroxide (H2O2) drove persistent STAT3 phosphorylation whereas STAT3 phosphorylation increased only transiently in response to LIF alone and was not increased by H2O2 alone. Surprisingly, increases in transcript levels of the direct STAT3 gene target SOCS3 were delayed during the combined LIF + H2O2 treatment, leading us to probe the impact of oxidative stress on STAT3 regulatory events. Indeed, LIF + H2O2 prolonged JAK activation, delayed STAT3 nuclear localisation, and caused relocalisation of nuclear STAT3 phosphatase TC-PTP (TC45) to the cytoplasm. In exploring the nuclear import/ export pathways, we observed disruption of nuclear/cytoplasmic distributions of Ran and importin-alpha3 in cells exposed to H2O2 and the resultant reduced nuclear trafficking of Classical importin-alpha/3-dependent protein cargoes. CRM1-mediated nuclear export persisted despite the oxidative stress insult, with sustained STAT3 Y705 phosphorylation enhancing STAT3 nuclear residency. Our studies thus reveal for the first time the striking impact of oxidative stress to sustain STAT3 phosphorylation and nuclear retention following disruption of multiple regulatory events, with significant implications for STAT3 function.

  9. Nifedipine treatment reduces resting calcium concentration, oxidative and apoptotic gene expression, and improves muscle function in dystrophic mdx mice.

    PubMed

    Altamirano, Francisco; Valladares, Denisse; Henríquez-Olguín, Carlos; Casas, Mariana; López, Jose R; Allen, Paul D; Jaimovich, Enrique

    2013-01-01

    Duchenne Muscular Dystrophy (DMD) is a recessive X-linked genetic disease, caused by mutations in the gene encoding dystrophin. DMD is characterized in humans and in mdx mice by a severe and progressive destruction of muscle fibers, inflammation, oxidative/nitrosative stress, and cell death. In mdx muscle fibers, we have shown that basal ATP release is increased and that extracellular ATP stimulation is pro-apoptotic. In normal fibers, depolarization-induced ATP release is blocked by nifedipine, leading us to study the potential therapeutic effect of nifedipine in mdx muscles and its relation with extracellular ATP signaling. Acute exposure to nifedipine (10 µM) decreased [Ca(2+)]r, NF-κB activity and iNOS expression in mdx myotubes. In addition, 6-week-old mdx mice were treated with daily intraperitoneal injections of nifedipine, 1 mg/Kg for 1 week. This treatment lowered the [Ca(2+)]r measured in vivo in the mdx vastus lateralis. We demonstrated that extracellular ATP levels were higher in adult mdx flexor digitorum brevis (FDB) fibers and can be significantly reduced after 1 week of treatment with nifedipine. Interestingly, acute treatment of mdx FDB fibers with apyrase, an enzyme that completely degrades extracellular ATP to AMP, reduced [Ca(2+)]r to a similar extent as was seen in FDB fibers after 1-week of nifedipine treatment. Moreover, we demonstrated that nifedipine treatment reduced mRNA levels of pro-oxidative/nitrosative (iNOS and gp91(phox)/p47(phox) NOX2 subunits) and pro-apoptotic (Bax) genes in mdx diaphragm muscles and lowered serum creatine kinase (CK) levels. In addition, nifedipine treatment increased muscle strength assessed by the inverted grip-hanging test and exercise tolerance measured with forced swimming test in mdx mice. We hypothesize that nifedipine reduces basal ATP release, thereby decreasing purinergic receptor activation, which in turn reduces [Ca(2+)]r in mdx skeletal muscle cells. The results in this work open new perspectives

  10. Nifedipine Treatment Reduces Resting Calcium Concentration, Oxidative and Apoptotic Gene Expression, and Improves Muscle Function in Dystrophic mdx Mice

    PubMed Central

    Henríquez-Olguín, Carlos; Casas, Mariana; López, Jose R.; Allen, Paul D.; Jaimovich, Enrique

    2013-01-01

    Duchenne Muscular Dystrophy (DMD) is a recessive X-linked genetic disease, caused by mutations in the gene encoding dystrophin. DMD is characterized in humans and in mdx mice by a severe and progressive destruction of muscle fibers, inflammation, oxidative/nitrosative stress, and cell death. In mdx muscle fibers, we have shown that basal ATP release is increased and that extracellular ATP stimulation is pro-apoptotic. In normal fibers, depolarization-induced ATP release is blocked by nifedipine, leading us to study the potential therapeutic effect of nifedipine in mdx muscles and its relation with extracellular ATP signaling. Acute exposure to nifedipine (10 µM) decreased [Ca2+]r, NF-κB activity and iNOS expression in mdx myotubes. In addition, 6-week-old mdx mice were treated with daily intraperitoneal injections of nifedipine, 1 mg/Kg for 1 week. This treatment lowered the [Ca2+]r measured in vivo in the mdx vastus lateralis. We demonstrated that extracellular ATP levels were higher in adult mdx flexor digitorum brevis (FDB) fibers and can be significantly reduced after 1 week of treatment with nifedipine. Interestingly, acute treatment of mdx FDB fibers with apyrase, an enzyme that completely degrades extracellular ATP to AMP, reduced [Ca2+]r to a similar extent as was seen in FDB fibers after 1-week of nifedipine treatment. Moreover, we demonstrated that nifedipine treatment reduced mRNA levels of pro-oxidative/nitrosative (iNOS and gp91phox/p47phox NOX2 subunits) and pro-apoptotic (Bax) genes in mdx diaphragm muscles and lowered serum creatine kinase (CK) levels. In addition, nifedipine treatment increased muscle strength assessed by the inverted grip-hanging test and exercise tolerance measured with forced swimming test in mdx mice. We hypothesize that nifedipine reduces basal ATP release, thereby decreasing purinergic receptor activation, which in turn reduces [Ca2+]r in mdx skeletal muscle cells. The results in this work open new perspectives towards

  11. Nifedipine treatment reduces resting calcium concentration, oxidative and apoptotic gene expression, and improves muscle function in dystrophic mdx mice.

    PubMed

    Altamirano, Francisco; Valladares, Denisse; Henríquez-Olguín, Carlos; Casas, Mariana; López, Jose R; Allen, Paul D; Jaimovich, Enrique

    2013-01-01

    Duchenne Muscular Dystrophy (DMD) is a recessive X-linked genetic disease, caused by mutations in the gene encoding dystrophin. DMD is characterized in humans and in mdx mice by a severe and progressive destruction of muscle fibers, inflammation, oxidative/nitrosative stress, and cell death. In mdx muscle fibers, we have shown that basal ATP release is increased and that extracellular ATP stimulation is pro-apoptotic. In normal fibers, depolarization-induced ATP release is blocked by nifedipine, leading us to study the potential therapeutic effect of nifedipine in mdx muscles and its relation with extracellular ATP signaling. Acute exposure to nifedipine (10 µM) decreased [Ca(2+)]r, NF-κB activity and iNOS expression in mdx myotubes. In addition, 6-week-old mdx mice were treated with daily intraperitoneal injections of nifedipine, 1 mg/Kg for 1 week. This treatment lowered the [Ca(2+)]r measured in vivo in the mdx vastus lateralis. We demonstrated that extracellular ATP levels were higher in adult mdx flexor digitorum brevis (FDB) fibers and can be significantly reduced after 1 week of treatment with nifedipine. Interestingly, acute treatment of mdx FDB fibers with apyrase, an enzyme that completely degrades extracellular ATP to AMP, reduced [Ca(2+)]r to a similar extent as was seen in FDB fibers after 1-week of nifedipine treatment. Moreover, we demonstrated that nifedipine treatment reduced mRNA levels of pro-oxidative/nitrosative (iNOS and gp91(phox)/p47(phox) NOX2 subunits) and pro-apoptotic (Bax) genes in mdx diaphragm muscles and lowered serum creatine kinase (CK) levels. In addition, nifedipine treatment increased muscle strength assessed by the inverted grip-hanging test and exercise tolerance measured with forced swimming test in mdx mice. We hypothesize that nifedipine reduces basal ATP release, thereby decreasing purinergic receptor activation, which in turn reduces [Ca(2+)]r in mdx skeletal muscle cells. The results in this work open new perspectives

  12. Silicon dioxide nanoparticles increase macrophage atherogenicity: Stimulation of cellular cytotoxicity, oxidative stress, and triglycerides accumulation.

    PubMed

    Petrick, Lauren; Rosenblat, Mira; Paland, Nicole; Aviram, Michael

    2016-06-01

    Nanoparticle research has focused on their toxicity in general, while increasing evidence points to additional specific adverse effects on atherosclerosis development. Arterial macrophage cholesterol and triglyceride (TG) accumulation and foam cell formation are the hallmark of early atherogenesis, leading to cardiovascular events. To investigate the in vitro atherogenic effects of silicon dioxide (SiO2 ), J774.1 cultured macrophages (murine cell line) were incubated with SiO2 nanoparticle (SP, d = 12 nm, 0-20 µg/mL), followed by cellular cytotoxicity, oxidative stress, TG and cholesterol metabolism analyses. A significant dose-dependent increase in oxidative stress (up to 164%), in cytotoxicity (up to 390% measured by lactate dehydrogenase (LDH) release), and in TG content (up to 63%) was observed in SiO2 exposed macrophages compared with control cells. A smaller increase in macrophage cholesterol mass (up to 22%) was noted. TG accumulation in macrophages was not due to a decrease in TG cell secretion or to an increased TG biosynthesis rate, but was the result of attenuated TG hydrolysis secondary to decreased lipase activity and both adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) protein expression (by 42 and 25%, respectively). Overall, SPs showed pro-atherogenic effects on macrophages as observed by cytotoxicity, increased oxidative stress and TG accumulation. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 713-723, 2016.

  13. Relationship between nitric oxide- and calcium-dependent signal transduction pathways in growth hormone release from dispersed goldfish pituitary cells.

    PubMed

    Chang, John P; Sawisky, Grant R; Davis, Philip J; Pemberton, Joshua G; Rieger, Aja M; Barreda, Daniel R

    2014-09-15

    Nitric oxide (NO) and Ca(2+) are two of the many intracellular signal transduction pathways mediating the control of growth hormone (GH) secretion from somatotropes by neuroendocrine factors. We have previously shown that the NO donor sodium nitroprusside (SNP) elicits Ca(2+) signals in identified goldfish somatotropes. In this study, we examined the relationships between NO- and Ca(2+)-dependent signal transduction mechanisms in GH secretion from primary cultures of dispersed goldfish pituitary cells. Morphologically identified goldfish somatotropes stained positively for an NO-sensitive dye indicating they may be a source of NO production. In 2h static incubation experiments, GH release responses to the NO donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP) were attenuated by CoCl2, nifedipine, verapamil, TMB-8, BHQ, and KN62. In column perifusion experiments, the ability of SNP to induce GH release was impaired in the presence of TMB-8, BHQ, caffeine, and thapsigargin, but not ryanodine. Caffeine-elicited GH secretion was not affected by the NO scavenger PTIO. These results suggest that NO-stimulated GH release is dependent on extracellular Ca(2+) availability and voltage-sensitive Ca(2+) channels, as well as intracellular Ca(2+) store(s) that possess BHQ- and/or thapsigargin-inhibited sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases, as well as TMB-8- and/or caffeine-sensitive, but not ryanodine-sensitive, Ca(2+)-release channels. Calmodulin kinase-II also likely participates in NO-elicited GH secretion but caffeine-induced GH release is not upstream of NO production. These findings provide insights into how NO actions many integrate with Ca(2+)-dependent signalling mechanisms in goldfish somatotropes and how such interactions may participate in the GH-releasing actions of regulators that utilize both NO- and Ca(2+)-dependent transduction pathways. PMID:25038498

  14. Relationship between nitric oxide- and calcium-dependent signal transduction pathways in growth hormone release from dispersed goldfish pituitary cells.

    PubMed

    Chang, John P; Sawisky, Grant R; Davis, Philip J; Pemberton, Joshua G; Rieger, Aja M; Barreda, Daniel R

    2014-09-15

    Nitric oxide (NO) and Ca(2+) are two of the many intracellular signal transduction pathways mediating the control of growth hormone (GH) secretion from somatotropes by neuroendocrine factors. We have previously shown that the NO donor sodium nitroprusside (SNP) elicits Ca(2+) signals in identified goldfish somatotropes. In this study, we examined the relationships between NO- and Ca(2+)-dependent signal transduction mechanisms in GH secretion from primary cultures of dispersed goldfish pituitary cells. Morphologically identified goldfish somatotropes stained positively for an NO-sensitive dye indicating they may be a source of NO production. In 2h static incubation experiments, GH release responses to the NO donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP) were attenuated by CoCl2, nifedipine, verapamil, TMB-8, BHQ, and KN62. In column perifusion experiments, the ability of SNP to induce GH release was impaired in the presence of TMB-8, BHQ, caffeine, and thapsigargin, but not ryanodine. Caffeine-elicited GH secretion was not affected by the NO scavenger PTIO. These results suggest that NO-stimulated GH release is dependent on extracellular Ca(2+) availability and voltage-sensitive Ca(2+) channels, as well as intracellular Ca(2+) store(s) that possess BHQ- and/or thapsigargin-inhibited sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases, as well as TMB-8- and/or caffeine-sensitive, but not ryanodine-sensitive, Ca(2+)-release channels. Calmodulin kinase-II also likely participates in NO-elicited GH secretion but caffeine-induced GH release is not upstream of NO production. These findings provide insights into how NO actions many integrate with Ca(2+)-dependent signalling mechanisms in goldfish somatotropes and how such interactions may participate in the GH-releasing actions of regulators that utilize both NO- and Ca(2+)-dependent transduction pathways.

  15. Effects of phosphates on microstructure and bioactivity of micro-arc oxidized calcium phosphate coatings on Mg-Zn-Zr magnesium alloy.

    PubMed

    Pan, Y K; Chen, C Z; Wang, D G; Zhao, T G

    2013-09-01

    Calcium phosphate (CaP) coatings were prepared on Mg-Zn-Zr magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH3COO)2Ca·H2O) and different phosphates (i.e. disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O), sodium phosphate (Na3PO4·H2O) and sodium hexametaphosphate((NaPO3)6)). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings. Simulated body fluid (SBF) immersion test was used to evaluate the coating bioactivity and degradability. Systemic toxicity test was used to evaluate the coating biocompatibility. Fluoride ion selective electrode (ISE) was used to measure F(-) ions concentration during 30 days SBF immersion. The CaP coatings effectively reduced the corrosion rate and the surfaces of CaP coatings were covered by a new layer formed of numerous needle-like and scale-like apatites. The formation of these calcium phosphate apatites indicates that the coatings have excellent bioactivity. The coatings formed in (NaPO3)6-containging electrolyte exhibit thicker thickness, higher adhesive strength, slower degradation rate, better apatite-inducing ability and biocompatibility.

  16. Effects of calcium carbonate, magnesium oxide and sodium citrate bicarbonate health supplements on the urinary risk factors for kidney stone formation.

    PubMed

    Allie, Shameez; Rodgers, Allen

    2003-01-01

    We describe a model to illustrate different chemical interactions that can occur in urine following ingestion of individual and combined health supplements. Two types of interactions are defined: synergism and addition. The model was applied to eight healthy males who participated in a study to investigate the chemical interactions between calcium carbonate, magnesium oxide and sodium citrate-bicarbonate health supplements on calcium oxalate urinary stone risk factors. Subjects ingested these components individually and in combination for 7 days. Twenty-four-hour urines were collected at baseline and during the final day of supplementation. These were analysed using standard laboratory techniques. Three different chemical interactions, all involving citrate, were identified: magnesium and citrate exerted a synergistic effect on lowering the relative superaturation (RS) of brushite; the same two components produced a synergistic effect on raising pH; finally, calcium and citrate exerted an additive effect on lowering the RS of uric acid. We propose that the novel approach described in this paper allows for the evaluation of individual, additive and synergistic interactions in the assessment of the efficacy of stone-risk reducing preparations.

  17. Steady and transient fluid shear stress stimulate NO release in osteoblasts through distinct biochemical pathways

    NASA Technical Reports Server (NTRS)

    McAllister, T. N.; Frangos, J. A.

    1999-01-01

    Fluid flow has been shown to be a potent stimulus in osteoblasts and osteocytes and may therefore play an important role in load-induced bone remodeling. The objective of this study was to investigate the characteristics of flow-activated pathways. Previously we reported that fluid flow stimulates rapid and continuous release of nitric oxide (NO) in primary rat calvarial osteoblasts. Here we demonstrate that flow-induced NO release is mediated by shear stress and that this response is distinctly biphasic. Transients in shear stress associated with the onset of flow stimulated a burst in NO production (8.2 nmol/mg of protein/h), while steady flow stimulated sustained NO production (2.2 nmol/mg of protein/h). Both G-protein inhibition and calcium chelation abolished the burst phase but had no effect on sustained production. Activation of G-proteins stimulated dose-dependent NO release in static cultures of both calvarial osteoblasts and UMR-106 osteoblast-like cells. Pertussis toxin had no effect on NO release. Calcium ionophore stimulated low levels of NO production within 15 minutes but had no effect on sustained production. Taken together, these data suggest that fluid shear stress stimulates NO release by two distinct pathways: a G-protein and calcium-dependent phase sensitive to flow transients, and a G-protein and calcium-independent pathway stimulated by sustained flow.

  18. Oxidative stability of a heme iron-fortified bakery product: Effectiveness of ascorbyl palmitate and co-spray-drying of heme iron with calcium caseinate.

    PubMed

    Alemán, Mercedes; Bou, Ricard; Tres, Alba; Polo, Javier; Codony, Rafael; Guardiola, Francesc

    2016-04-01

    Fortification of food products with iron is a common strategy to prevent or overcome iron deficiency. However, any form of iron is a pro-oxidant and its addition will cause off-flavours and reduce a product's shelf life. A highly bioavailable heme iron ingredient was selected to fortify a chocolate cream used to fill sandwich-type cookies. Two different strategies were assessed for avoiding the heme iron catalytic effect on lipid oxidation: ascorbyl palmitate addition and co-spray-drying of heme iron with calcium caseinate. Oxidation development and sensory acceptability were monitored in the cookies over one-year of storage at room temperature in the dark. The addition of ascorbyl palmitate provided protection against oxidation and loss of tocopherols and tocotrienols during the preparation of cookies. In general, ascorbyl palmitate, either alone or in combination with the co-spray-dried heme iron, prevented primary oxidation and hexanal formation during storage. The combination of both strategies resulted in cookies that were acceptable from a sensory point of view after 1year of storage.

  19. Iron oxide nanoparticle-mediated hyperthermia stimulates dispersal in bacterial biofilms and enhances antibiotic efficacy

    PubMed Central

    Nguyen, Thuy-Khanh; Duong, Hien T. T.; Selvanayagam, Ramona; Boyer, Cyrille; Barraud, Nicolas

    2015-01-01

    The dispersal phase that completes the biofilm lifecycle is of particular interest for its potential to remove recalcitrant, antimicrobial tolerant biofilm infections. Here we found that temperature is a cue for biofilm dispersal and a rise by 5 °C or more can induce the detachment of Pseudomonas aeruginosa biofilms. Temperature upshifts were found to decrease biofilm biomass and increase the number of viable freely suspended cells. The dispersal response appeared to involve the secondary messenger cyclic di-GMP, which is central to a genetic network governing motile to sessile transitions in bacteria. Furthermore, we used poly((oligo(ethylene glycol) methyl ether acrylate)-block-poly(monoacryloxy ethyl phosphate)-stabilized iron oxide nanoparticles (POEGA-b-PMAEP@IONPs) to induce local hyperthermia in established biofilms upon exposure to a magnetic field. POEGA-b-PMAEP@IONPs were non-toxic to bacteria and when heated induced the detachment of biof