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Sample records for calcium 48 target

  1. Proton bombarded reactions of Calcium target nuclei

    Directory of Open Access Journals (Sweden)

    Tel Eyyup

    2017-01-01

    Full Text Available In this study, proton bombarded nuclear reactions calculations of Calcium target nuclei have been investigated in the incident proton energy range of 1–50 MeV. The excitation functions for 40Ca target nuclei reactions have been calculated by using PCROSS nuclear reaction calculation code. Weisskopf-Ewing and the full exciton models were used for equilibrium and for pre-equilibrium calculations, respectively. The excitation functions for 40Ca target nuclei reactions (p,α, (p,n, (p,p have been calculated using the semi-empirical formula Tel et al. [5].

  2. 44gSc from metal calcium targets for PET

    DEFF Research Database (Denmark)

    Severin, Gregory; Gagnon, K.; Engle, J. W.

    2012-01-01

    A low-cost and efficient method for producing pre-clinical scale quantities of 44gSc is presented. Production involves proton irradiation of natural unenriched calcium metal followed by rapid separation of radioscandium from the target using hydroxmate functionalized resin.© 2012 American Institu...

  3. Low threshold T‐type calcium channels as targets for novel epilepsy treatments

    National Research Council Canada - National Science Library

    Powell, Kim L; Cain, Stuart M; Snutch, Terrance P; O'Brien, Terence J

    2014-01-01

    .... T ‐type calcium channels are expressed widely throughout the brain and peripheral tissues, and thus have been proposed as therapeutic targets for a variety of diseases such as epilepsy, insomnia, pain...

  4. Separation of calcium-48 isotope by crown ether chromatography using ethanol/hydrochloric acid mixed solvent.

    Science.gov (United States)

    Okumura, Shin; Umehara, Saori; Fujii, Yasuhiko; Nomura, Masao; Kaneshiki, Toshitaka; Ozawa, Masaki; Kishimoto, Tadafumi

    2015-10-09

    Benzo-18-crown-6 ether resin embedded in porous silica beads was synthesized and used as the packing material for chromatographic separation of (48)Ca isotope. The aim of the present work is to develop efficient isotope enrichment process for double β decay nuclide (48)Ca. To this end, ethanol/HCl mixed solvent was selected as the medium for the chromatographic separation. Adsorption of calcium on the resin was studied at different HCl concentrations and different ethanol mixing ratios in batch-wise experiments. A very interesting phenomenon was observed; Ca adsorption is controlled not by the overall HCl concentration of the mixed solvent, but by the initial concentration of added HCl solution. Calcium break-through chromatography experiments were conducted by using 75v/v% ethanol/25v/v% 8M HCl mixed solvent at different flow rates. The isotope separation coefficient between (48)Ca and (40)Ca was determined as 3.8×10(-3), which is larger than that of pure HCl solution system. Discussion is extended to the chromatographic HETP, height equivalent to a theoretical plate. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  6. Targeting Calcium Signaling Induces Epigenetic Reactivation of Tumor Suppressor Genes in Cancer.

    Science.gov (United States)

    Raynal, Noël J-M; Lee, Justin T; Wang, Youjun; Beaudry, Annie; Madireddi, Priyanka; Garriga, Judith; Malouf, Gabriel G; Dumont, Sarah; Dettman, Elisha J; Gharibyan, Vazganush; Ahmed, Saira; Chung, Woonbok; Childers, Wayne E; Abou-Gharbia, Magid; Henry, Ryan A; Andrews, Andrew J; Jelinek, Jaroslav; Cui, Ying; Baylin, Stephen B; Gill, Donald L; Issa, Jean-Pierre J

    2016-03-15

    Targeting epigenetic pathways is a promising approach for cancer therapy. Here, we report on the unexpected finding that targeting calcium signaling can reverse epigenetic silencing of tumor suppressor genes (TSG). In a screen for drugs that reactivate silenced gene expression in colon cancer cells, we found three classical epigenetic targeted drugs (DNA methylation and histone deacetylase inhibitors) and 11 other drugs that induced methylated and silenced CpG island promoters driving a reporter gene (GFP) as well as endogenous TSGs in multiple cancer cell lines. These newly identified drugs, most prominently cardiac glycosides, did not change DNA methylation locally or histone modifications globally. Instead, all 11 drugs altered calcium signaling and triggered calcium-calmodulin kinase (CamK) activity, leading to MeCP2 nuclear exclusion. Blocking CamK activity abolished gene reactivation and cancer cell killing by these drugs, showing that triggering calcium fluxes is an essential component of their epigenetic mechanism of action. Our data identify calcium signaling as a new pathway that can be targeted to reactivate TSGs in cancer. ©2015 American Association for Cancer Research.

  7. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  8. Subcellular targeting of nine calcium-dependent protein kinase isoforms from Arabidopsis

    Science.gov (United States)

    Dammann, Christian; Ichida, Audrey; Hong, Bimei; Romanowsky, Shawn M.; Hrabak, Estelle M.; Harmon, Alice C.; Pickard, Barbara G.; Harper, Jeffrey F.; Evans, M. L. (Principal Investigator)

    2003-01-01

    Calcium-dependent protein kinases (CDPKs) are specific to plants and some protists. Their activation by calcium makes them important switches for the transduction of intracellular calcium signals. Here, we identify the subcellular targeting potentials for nine CDPK isoforms from Arabidopsis, as determined by expression of green fluorescent protein (GFP) fusions in transgenic plants. Subcellular locations were determined by fluorescence microscopy in cells near the root tip. Isoforms AtCPK3-GFP and AtCPK4-GFP showed a nuclear and cytosolic distribution similar to that of free GFP. Membrane fractionation experiments confirmed that these isoforms were primarily soluble. A membrane association was observed for AtCPKs 1, 7, 8, 9, 16, 21, and 28, based on imaging and membrane fractionation experiments. This correlates with the presence of potential N-terminal acylation sites, consistent with acylation as an important factor in membrane association. All but one of the membrane-associated isoforms targeted exclusively to the plasma membrane. The exception was AtCPK1-GFP, which targeted to peroxisomes, as determined by covisualization with a peroxisome marker. Peroxisome targeting of AtCPK1-GFP was disrupted by a deletion of two potential N-terminal acylation sites. The observation of a peroxisome-located CDPK suggests a mechanism for calcium regulation of peroxisomal functions involved in oxidative stress and lipid metabolism.

  9. Low threshold T-type calcium channels as targets for novel epilepsy treatments.

    Science.gov (United States)

    Powell, Kim L; Cain, Stuart M; Snutch, Terrance P; O'Brien, Terence J

    2014-05-01

    Low voltage-activated T-type calcium channels were originally cloned in the 1990s and much research has since focused on identifying the physiological roles of these channels in health and disease states. T-type calcium channels are expressed widely throughout the brain and peripheral tissues, and thus have been proposed as therapeutic targets for a variety of diseases such as epilepsy, insomnia, pain, cancer and hypertension. This review discusses the literature concerning the role of T-type calcium channels in physiological and pathological processes related to epilepsy. T-type calcium channels have been implicated in pathology of both the genetic and acquired epilepsies and several anti-epileptic drugs (AEDs) in clinical use are known to suppress seizures via inhibition of T-type calcium channels. Despite the fact that more than 15 new AEDs have become clinically available over the past 20 years at least 30% of epilepsy patients still fail to achieve seizure control, and many patients experience unwanted side effects. Furthermore there are no treatments that prevent the development of epilepsy or mitigate the epileptic state once established. Therefore there is an urgent need for the development of new AEDs that are effective in patients with drug resistant epilepsy, are anti-epileptogenic and are better tolerated. We also review the mechanisms of action of the current AEDs with known effects on T-type calcium channels and discuss novel compounds that are being investigated as new treatments for epilepsy. © 2013 The British Pharmacological Society.

  10. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  11. Manufacturing of calcium, lithium and molybdenum targets for use in nuclear physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kheswa, N.Y., E-mail: kheswa@tlabs.ac.z [iThemba Laboratory for Accelerator Based Science, P.O. Box 722, Somerset West 7129, Western Cape (South Africa); Papka, P.; Buthelezi, E.Z.; Lieder, R.M.; Neveling, R.; Newman, R.T. [iThemba Laboratory for Accelerator Based Science, P.O. Box 722, Somerset West 7129, Western Cape (South Africa)

    2010-02-11

    This paper describes methods used in the manufacturing of chemically reactive targets such as calcium ({sup nat}Ca), lithium-6 ({sup 6}Li) and molybdenum-97 ({sup 97}Mo) for nuclear physics experiments at the iThemba LABS cyclotron facility (Faure, South Africa). Due to the chemical properties of these materials a suitable and controlled environment was established in order to minimize oxygen contamination of targets. Calcium was prepared by means of vacuum evaporation while lithium was cold rolled to a desired thickness. In the case of molybdenum, the metallic powder was melted under vacuum using an e-gun followed by cold rolling of the metal bead to a desired thickness. In addition, latest developments toward the establishment of a dedicated nuclear physics target laboratory are discussed.

  12. Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction of human progenitors.

    Science.gov (United States)

    Eyckmans, Jeroen; Roberts, Scott J; Bolander, Johanna; Schrooten, Jan; Chen, Christopher S; Luyten, Frank P

    2013-06-01

    Although calcium phosphate-containing biomaterials are promising scaffolds for bone regenerative strategies, the osteoinductive capacity of such materials is poorly understood. In this study, we investigated whether endogenous mechanisms of in vivo calcium phosphate-driven, ectopic bone formation could be identified and used to induce enhanced differentiation in vitro of the same progenitor population. To accomplish this, human periosteum derived cells (hPDCs) were seeded on hydroxyapatite/collagen scaffolds (calcium phosphate rich matrix or CPRM), or on decalcified scaffolds (calcium phosphate depleted matrix or CPDM), followed by subcutaneous implantation in nude mice to trigger ectopic bone formation. In this system, osteoblast differentiation occurred in CPRM scaffolds, but not in CPDM scaffolds. Gene expression was assessed by human full-genome microarray at 20 h after seeding, and 2, 8 and 18 days after implantation. In both matrices, implantation of the cell constructs triggered a similar gene expression cascade, however, gene expression dynamics progressed faster in CPRM scaffolds than in CPDM scaffolds. The difference in gene expression dynamics was associated with differential activation of hub genes and molecular signaling pathways related to calcium signaling (CREB), inflammation (TNFα, NFkB, and IL6) and bone development (TGFβ, β-catenin, BMP, EGF, and ERK signaling). Starting from this set of pathways, a growth factor cocktail was developed that robustly enhanced osteogenesis in vitro and in vivo. Taken together, our data demonstrate that through the identification and subsequent stimulation of genes, proteins and signaling pathways associated with calcium phosphate mediated osteoinduction, a focused approach to develop targeted differentiation protocols in adult progenitor cells can be achieved. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Target size of calcium pump protein from skeletal muscle sarcoplasmic reticulum.

    Science.gov (United States)

    Hymel, L; Maurer, A; Berenski, C; Jung, C Y; Fleischer, S

    1984-04-25

    The oligomeric size of calcium pump protein (CPP) in fast skeletal muscle sarcoplasmic reticulum membrane was determined using target theory analysis of radiation inactivation data. There was a parallel decrease of Ca2+-ATPase and calcium pumping activities with increasing radiation dose. The loss of staining intensity of the CPP band, observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, also correlated directly with the loss of activity. The target size molecular weight of the CPP in the normal sarcoplasmic reticulum membrane ranged between 210,000 and 250,000, which is consistent with a dimeric structure. Essentially the same size is obtained for the non-phosphorylated CPP or for the phosphoenzyme form generated from either ATP (E1 state) or inorganic phosphate (E2 state). Hence, the oligomeric state of the pump does not appear to change during the catalytic cycle. Similar results were obtained with reconstituted sarcoplasmic reticulum membrane vesicles with different lipid to protein ratios. We conclude that the CPP is a dimer in both native and reconstituted sarcoplasmic reticulum membranes. The target size of the calcium-binding protein (calsequestrin) was found to be 50,000 daltons, approximating a monomer.

  14. Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

    Energy Technology Data Exchange (ETDEWEB)

    Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore)

    2012-06-15

    Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

  15. Assessing potential targets of calcium action in light-modulated gravitropism

    Science.gov (United States)

    Roux, S. J.

    1995-01-01

    Light, through the mediation of the pigment phytochrome, modulates the gravitropic response of the shoots and roots of many plants. The transduction of both light and gravity stimuli appears to involve Ca(2+)-regulated steps, one or more of which may represent points of intersection between the two transduction chains. To be confident that Ca2+ plays a critical role in stimulus-response coupling for gravitropism, it will be important to identify specific targets of Ca2+ action whose function can be clearly linked to the regulation of growth. Calcium typically exerts its influence on cell metabolism through binding to and activating key regulatory proteins. The three best characterized of these proteins in plants are the calmodulins, calcium-dependent protein kinases, and annexins. In this review we summarize what is known about the structure and function of these proteins and speculate on how their activation by Ca2+ could influence the differential growth response of gravitropism.

  16. Characterization and subcellular targeting of GCaMP-type genetically-encoded calcium indicators.

    Directory of Open Access Journals (Sweden)

    Tianyi Mao

    2008-03-01

    Full Text Available Genetically-encoded calcium indicators (GECIs hold the promise of monitoring [Ca(2+] in selected populations of neurons and in specific cellular compartments. Relating GECI fluorescence to neuronal activity requires quantitative characterization. We have characterized a promising new genetically-encoded calcium indicator-GCaMP2-in mammalian pyramidal neurons. Fluorescence changes in response to single action potentials (17+/-10% DeltaF/F [mean+/-SD] could be detected in some, but not all, neurons. Trains of high-frequency action potentials yielded robust responses (302+/-50% for trains of 40 action potentials at 83 Hz. Responses were similar in acute brain slices from in utero electroporated mice, indicating that long-term expression did not interfere with GCaMP2 function. Membrane-targeted versions of GCaMP2 did not yield larger signals than their non-targeted counterparts. We further targeted GCaMP2 to dendritic spines to monitor Ca(2+ accumulations evoked by activation of synaptic NMDA receptors. We observed robust DeltaF/F responses (range: 37%-264% to single spine uncaging stimuli that were correlated with NMDA receptor currents measured through a somatic patch pipette. One major drawback of GCaMP2 was its low baseline fluorescence. Our results show that GCaMP2 is improved from the previous versions of GCaMP and may be suited to detect bursts of high-frequency action potentials and synaptic currents in vivo.

  17. Neospora caninum calcium-dependent protein kinase 1 is an effective drug target for neosporosis therapy.

    Science.gov (United States)

    Ojo, Kayode K; Reid, Molly C; Kallur Siddaramaiah, Latha; Müller, Joachim; Winzer, Pablo; Zhang, Zhongsheng; Keyloun, Katelyn R; Vidadala, Rama Subba Rao; Merritt, Ethan A; Hol, Wim G J; Maly, Dustin J; Fan, Erkang; Van Voorhis, Wesley C; Hemphill, Andrew

    2014-01-01

    Despite the enormous economic importance of Neospora caninum related veterinary diseases, the number of effective therapeutic agents is relatively small. Development of new therapeutic strategies to combat the economic impact of neosporosis remains an important scientific endeavor. This study demonstrates molecular, structural and phenotypic evidence that N. caninum calcium-dependent protein kinase 1 (NcCDPK1) is a promising molecular target for neosporosis drug development. Recombinant NcCDPK1 was expressed, purified and screened against a select group of bumped kinase inhibitors (BKIs) previously shown to have low IC50s against Toxoplasma gondii CDPK1 and T. gondii tachyzoites. NcCDPK1 was inhibited by low concentrations of BKIs. The three-dimensional structure of NcCDPK1 in complex with BKIs was studied crystallographically. The BKI-NcCDPK1 structures demonstrated the structural basis for potency and selectivity. Calcium-dependent conformational changes in solution as characterized by small-angle X-ray scattering are consistent with previous structures in low Calcium-state but different in the Calcium-bound active state than predicted by X-ray crystallography. BKIs effectively inhibited N. caninum tachyzoite proliferation in vitro. Electron microscopic analysis of N. caninum cells revealed ultra-structural changes in the presence of BKI compound 1294. BKI compound 1294 interfered with an early step in Neospora tachyzoite host cell invasion and egress. Prolonged incubation in the presence of 1294 interfered produced observable interference with viability and replication. Oral dosing of BKI compound 1294 at 50 mg/kg for 5 days in established murine neosporosis resulted in a 10-fold reduced cerebral parasite burden compared to untreated control. Further experiments are needed to determine the PK, optimal dosage, and duration for effective treatment in cattle and dogs, but these data demonstrate proof-of-concept for BKIs, and 1294 specifically, for therapy of bovine

  18. Neospora caninum calcium-dependent protein kinase 1 is an effective drug target for neosporosis therapy.

    Directory of Open Access Journals (Sweden)

    Kayode K Ojo

    Full Text Available Despite the enormous economic importance of Neospora caninum related veterinary diseases, the number of effective therapeutic agents is relatively small. Development of new therapeutic strategies to combat the economic impact of neosporosis remains an important scientific endeavor. This study demonstrates molecular, structural and phenotypic evidence that N. caninum calcium-dependent protein kinase 1 (NcCDPK1 is a promising molecular target for neosporosis drug development. Recombinant NcCDPK1 was expressed, purified and screened against a select group of bumped kinase inhibitors (BKIs previously shown to have low IC50s against Toxoplasma gondii CDPK1 and T. gondii tachyzoites. NcCDPK1 was inhibited by low concentrations of BKIs. The three-dimensional structure of NcCDPK1 in complex with BKIs was studied crystallographically. The BKI-NcCDPK1 structures demonstrated the structural basis for potency and selectivity. Calcium-dependent conformational changes in solution as characterized by small-angle X-ray scattering are consistent with previous structures in low Calcium-state but different in the Calcium-bound active state than predicted by X-ray crystallography. BKIs effectively inhibited N. caninum tachyzoite proliferation in vitro. Electron microscopic analysis of N. caninum cells revealed ultra-structural changes in the presence of BKI compound 1294. BKI compound 1294 interfered with an early step in Neospora tachyzoite host cell invasion and egress. Prolonged incubation in the presence of 1294 interfered produced observable interference with viability and replication. Oral dosing of BKI compound 1294 at 50 mg/kg for 5 days in established murine neosporosis resulted in a 10-fold reduced cerebral parasite burden compared to untreated control. Further experiments are needed to determine the PK, optimal dosage, and duration for effective treatment in cattle and dogs, but these data demonstrate proof-of-concept for BKIs, and 1294 specifically, for

  19. Why Basic Calcium Phosphate Crystals Should Be Targeted In the Treatment of Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Claire-Louise Murphy

    2014-07-01

    Full Text Available Osteoarthritis (OA is the most common form of arthritis and results in significant social, psychological, and economic costs. It is characterised by progressive cartilage loss, bone remodelling, osteophyte formation, and synovial inflammation with resultant joint pain and disability. Since OA affects the entire joint, it is not surprising that there has been difficulty developing an effective targeted treatment. Treatments available for structural disease modification are limited. Current options appear to mostly reduce symptoms. Basic calcium phosphate (BCP crystals represent a potential therapeutic target in OA; they have been found in 100% of knee and hip cartilages removed at joint replacement. Intra-articular BCP crystals are associated with large joint effusions and dissolution of intra-articular structures, synovial proliferation, and marked degeneration as assessed by diagnostic imaging. While BCP deposition has been considered by many to be simply a consequence of advanced OA, there is substantial evidence to support BCP crystal deposition as an active pathogenic mediator of OA. BCP crystals exhibit a multiplicity of biologic effects in vitro including the ability to stimulate mitogenesis and prostaglandin, cytokine, and matrix metalloproteinase (MMP synthesis in a number of cell types including macrophages, synovial fibroblasts, and chondrocytes. BCP crystals also contribute to inflammation in OA through direct interaction with the innate immune system. Intra-articular BCP crystals can elicit synovial inflammation and cartilage degradation in mice in vivo . Although intra-articular BCP crystals are difficult to detect at the bedside, advances in modern technology should allow improved identification and quantitation of BCP crystals. Our article focuses on why basic calcium crystals are important in the pathogenesis of OA. There is ample evidence that BCP crystals should be explored as a therapeutic target in OA.

  20. Calcium channels in the brain as targets for the calcium-channel modulators used in the treatment of neurological disorders

    NARCIS (Netherlands)

    Peters, Thies; WILFFERT, B; VANHOUTTE, PM; VANZWIETEN, PA

    1991-01-01

    Recent investigations of calcium channels in brain cells by voltage-clamp techniques have revealed that, in spite of electrophysiological similarities, the pharmacological properties of these channels differ considerably from channels in peripheral tissues, e.g., heart and smooth muscle. Therefore,

  1. L-type calcium channel targeting and local signalling in cardiac myocytes.

    Science.gov (United States)

    Shaw, Robin M; Colecraft, Henry M

    2013-05-01

    In the heart, Ca(2+) influx via Ca(V)1.2 L-type calcium channels (LTCCs) is a multi-functional signal that triggers muscle contraction, controls action potential duration, and regulates gene expression. The use of LTCC Ca(2+) as a multi-dimensional signalling molecule in the heart is complicated by several aspects of cardiac physiology. Cytosolic Ca(2+) continuously cycles between ~100 nM and ~1 μM with each heartbeat due to Ca(2+) linked signalling from LTCCs to ryanodine receptors. This rapid cycling raises the question as to how cardiac myocytes distinguish the Ca(2+) fluxes originating through L-type channels that are dedicated to contraction from Ca(2+) fluxes originating from other L-type channels that are used for non-contraction-related signalling. In general, disparate Ca(2+) sources in cardiac myocytes such as current through differently localized LTCCs as well as from IP3 receptors can signal selectively to Ca(2+)-dependent effectors in local microdomains that can be impervious to the cytoplasmic Ca(2+) transients that drive contraction. A particular challenge for diversified signalling via cardiac LTCCs is that they are voltage-gated and, therefore, open and presumably flood their microdomains with Ca(2+) with each action potential. Thus spatial localization of Cav1.2 channels to different types of microdomains of the ventricular cardiomyocyte membrane as well as the existence of particular macromolecular complexes in each Cav1.2 microdomain are important to effect different types of Cav1.2 signalling. In this review we examine aspects of Cav1.2 structure, targeting and signalling in two specialized membrane microdomains--transverse tubules and caveolae.

  2. The calcium-dependent protein kinase 1 from Toxoplasma gondii as target for structure-based drug design.

    Science.gov (United States)

    Cardew, Emily M; Verlinde, Christophe L M J; Pohl, Ehmke

    2018-02-01

    The apicomplexan protozoan parasites include the causative agents of animal and human diseases ranging from malaria (Plasmodium spp.) to toxoplasmosis (Toxoplasma gondii). The complex life cycle of T. gondii is regulated by a unique family of calcium-dependent protein kinases (CDPKs) that have become the target of intensive efforts to develop new therapeutics. In this review, we will summarize structure-based strategies, recent successes and future directions in the pursuit of specific and selective inhibitors of T. gondii CDPK1.

  3. Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction of human progenitors in vitro and in vivo

    Science.gov (United States)

    Eyckmans, J.; Roberts, S.J.; Bolander, J.; Schrooten, J.; Chen, C.S.; Luyten, F.P.

    2014-01-01

    Although calcium phosphate-containing biomaterials are promising scaffolds for bone regenerative strategies, the osteoinductive capacity of such materials is poorly understood. In this study, we investigated whether endogenous mechanisms of in vivo calcium phosphate-driven, ectopic bone formation could be identified and used to induce enhanced differentiation in vitro of the same progenitor population. To accomplish this, human periosteum derived cells (hPDCs) were seeded on hydroxyapatite/collagen scaffolds (calcium phosphate rich matrix or CPRM), or on decalcified scaffolds (calcium phosphate depleted matrix or CPDM), followed by subcutaneous implantation in nude mice to trigger ectopic bone formation. In this system, osteoblast differentiation occurred in CPRM scaffolds, but not in CPDM scaffolds. Gene expression was assessed by human full-genome microarray at 20 hours after seeding, and 2, 8 and 18 days after implantation. In both matrices, implantation of the cell constructs triggered a similar gene expression cascade, however, gene expression dynamics progressed faster in CPRM scaffolds than in CPDM scaffolds. The difference in gene expression dynamics was associated with differential activation of hub genes and molecular signaling pathways related to calcium signaling (CREB), inflammation (TNFα, NFkB, and IL6) and bone development (TGFβ, β-catenin, BMP, EGF, and ERK signaling). Starting from this set of pathways, a growth factor cocktail was developed that robustly enhanced osteogenesis in vitro and in vivo. Taken together, our data demonstrate that through the identification and subsequent stimulation of genes, proteins and signaling pathways associated with calcium phosphate mediated osteoinduction, a focused approach to develop targeted differentiation protocols in adult progenitor cells can be achieved. PMID:23537666

  4. A FluoPol-ABPP PAD2 high-throughput screen identifies the first calcium site inhibitor targeting the PADs.

    Science.gov (United States)

    Lewallen, Daniel M; Bicker, Kevin L; Madoux, Franck; Chase, Peter; Anguish, Lynne; Coonrod, Scott; Hodder, Peter; Thompson, Paul R

    2014-04-18

    The protein arginine deiminases (PADs) catalyze the post-translational hydrolysis of peptidyl-arginine to form peptidyl-citrulline in a process termed deimination or citrullination. PADs likely play a role in the progression of a range of disease states because dysregulated PAD activity is observed in a host of inflammatory diseases and cancer. For example, recent studies have shown that PAD2 activates ERα target gene expression in breast cancer cells by citrullinating histone H3 at ER target promoters. To date, all known PAD inhibitors bind directly to the enzyme active site. PADs, however, also require calcium ions to drive a conformational change between the inactive apo-state and the fully active calcium bound holoenzyme, suggesting that it would be possible to identify inhibitors that bind the apoenzyme and prevent this conformational change. As such, we set out to develop a screen that can identify PAD2 inhibitors that bind to either the apo or calcium bound form of PAD2. Herein, we provide definitive proof of concept for this approach and report the first PAD inhibitor, ruthenium red (Ki of 17 μM), to preferentially bind the apoenzyme.

  5. Structural Insights into Membrane Targeting by the Flagellar Calcium-binding Protein (FCaBP) a Myristoylated and Palmitoylated Calcium Sensor in Trypanosoma cruzi

    Energy Technology Data Exchange (ETDEWEB)

    J Wingard; J Ladner; M Vanarotti; A Fisher; H Robinson; K Buchanan; D Engman; J Ames

    2011-12-31

    The flagellar calcium-binding protein (FCaBP) of the protozoan Trypanosoma cruzi is targeted to the flagellar membrane where it regulates flagellar function and assembly. As a first step toward understanding the Ca{sup 2+}-induced conformational changes important for membrane-targeting, we report here the x-ray crystal structure of FCaBP in the Ca{sup 2+}-free state determined at 2.2{angstrom} resolution. The first 17 residues from the N terminus appear unstructured and solvent-exposed. Residues implicated in membrane targeting (Lys-19, Lys-22, and Lys-25) are flanked by an exposed N-terminal helix (residues 26-37), forming a patch of positive charge on the protein surface that may interact electrostatically with flagellar membrane targets. The four EF-hands in FCaBP each adopt a 'closed conformation' similar to that seen in Ca{sup 2+}-free calmodulin. The overall fold of FCaBP is closest to that of grancalcin and other members of the penta EF-hand superfamily. Unlike the dimeric penta EF-hand proteins, FCaBP lacks a fifth EF-hand and is monomeric. The unstructured N-terminal region of FCaBP suggests that its covalently attached myristoyl group at the N terminus may be solvent-exposed, in contrast to the highly sequestered myristoyl group seen in recoverin and GCAP1. NMR analysis demonstrates that the myristoyl group attached to FCaBP is indeed solvent-exposed in both the Ca{sup 2+}-free and Ca{sup 2+}-bound states, and myristoylation has no effect on protein structure and folding stability. We propose that exposed acyl groups at the N terminus may anchor FCaBP to the flagellar membrane and that Ca{sup 2+}-induced conformational changes may control its binding to membrane-bound protein targets..

  6. Calcium channel TRPV6 as a potential therapeutic target in estrogen receptor-negative breast cancer.

    Science.gov (United States)

    Peters, Amelia A; Simpson, Peter T; Bassett, Johnathon J; Lee, Jane M; Da Silva, Leonard; Reid, Lynne E; Song, Sarah; Parat, Marie-Odile; Lakhani, Sunil R; Kenny, Paraic A; Roberts-Thomson, Sarah J; Monteith, Gregory R

    2012-10-01

    Calcium signaling is a critical regulator of cell proliferation. Elevated expression of calcium channels and pumps is a characteristic of some cancers, including breast cancer. We show that the plasma membrane calcium channel TRPV6, which is highly selective for Ca(2+), is overexpressed in some breast cancer cell lines. Silencing of TRPV6 expression in a breast cancer cell line with increased endogenous TRPV6 expression leads to a reduction in basal calcium influx and cellular proliferation associated with a reduction in DNA synthesis. TRPV6 gene amplification was identified as one mechanism of TRPV6 overexpression in a subset of breast cancer cell lines and breast tumor samples. Analysis of two independent microarray expression datasets from breast tumor samples showed that increased TRPV6 expression is a feature of estrogen receptor (ER)-negative breast tumors encompassing the basal-like molecular subtype, as well as HER2-positive tumors. Breast cancer patients with high TRPV6 levels had decreased survival compared with patients with low or intermediate TRPV6 expression. Our findings suggest that inhibitors of TRPV6 may offer a novel therapeutic strategy for the treatment of ER-negative breast cancers.

  7. Development and Validation of A 48-Target Analytical Method for High-throughput Monitoring of Genetically Modified Organisms

    Science.gov (United States)

    Li, Xiaofei; Wu, Yuhua; Li, Jun; Li, Yunjing; Long, Likun; Li, Feiwu; Wu, Gang

    2015-01-01

    The rapid increase in the number of genetically modified (GM) varieties has led to a demand for high-throughput methods to detect genetically modified organisms (GMOs). We describe a new dynamic array-based high throughput method to simultaneously detect 48 targets in 48 samples on a Fludigm system. The test targets included species-specific genes, common screening elements, most of the Chinese-approved GM events, and several unapproved events. The 48 TaqMan assays successfully amplified products from both single-event samples and complex samples with a GMO DNA amount of 0.05 ng, and displayed high specificity. To improve the sensitivity of detection, a preamplification step for 48 pooled targets was added to enrich the amount of template before performing dynamic chip assays. This dynamic chip-based method allowed the synchronous high-throughput detection of multiple targets in multiple samples. Thus, it represents an efficient, qualitative method for GMO multi-detection. PMID:25556930

  8. New Conotoxin SO-3 Targeting N-type Voltage-Sensitive Calcium Channels

    Directory of Open Access Journals (Sweden)

    Lei Wen

    2006-04-01

    Full Text Available Selective blockers of the N-type voltage-sensitive calcium (CaV channels are useful in the management of severe chronic pain. Here, the structure and function characteristics of a novel N-type CaV channel blocker, SO-3, are reviewed. SO-3 is a 25-amino acid conopeptide originally derived from the venom of Conus striatus, and contains the same 4-loop, 6-cysteine framework (C-C-CC-C-C as O-superfamily conotoxins. The synthetic SO-3 has high analgesic activity similar to ω-conotoxin MVIIA (MVIIA, a selective N-type CaV channel blocker approved in the USA and Europe for the alleviation of persistent pain states. In electrophysiological studies, SO-3 shows more selectivity towards the N-type CaV channels than MVIIA. The dissimilarity between SO-3 and MVIIA in the primary and tertiary structures is further discussed in an attempt to illustrate the difference in selectivity of SO-3 and MVIIA towards N-type CaV channels.

  9. Mitochondria and calcium flux as targets of neuroprotection caused by minocycline in cerebellar granule cells

    OpenAIRE

    Garcia-Martinez, Eva Maria; Sanz-Blasco, Sara; Karachitos, Andonis; Bandez, Miguel J.; Fernandez-Gomez, Francisco J; Perez-Alvarez, Sergio; Mera, Raquel Maria Melero Fernandez De; Jordan, Maria J.; Aguirre, Norberto; Galindo, Maria F.; Villalobos, Carlos; Navarro, Ana; Kmita, Hanna; Jordán, Joaquín

    2009-01-01

    Abstract Minocycline, an antibiotic of the tetracycline family, has attracted considerable interest for its theoretical therapeutic applications in neurodegenerative diseases. However, the mechanism of action underlying its effect remains elusive. Here we have studied the effect of minocycline under excitotoxic conditions. Fluorescence and bioluminescence imaging studies in rat cerebellar granular neuron cultures using fura-2/AM and mitochondria-targeted aequorin revealed that mino...

  10. 48 CFR 52.216-17 - Incentive Price Revision-Successive Targets.

    Science.gov (United States)

    2010-10-01

    ... this contract, using the statement of costs incurred plus an estimate of costs to complete performance... of the total initial target cost. (3) If the total firm target cost plus the total firm target profit... total firm target cost, the adjustment is the total firm target profit, plus _ percent of the amount by...

  11. Efficiency of calcium phosphate composite nanoparticles in targeting Ehrlich carcinoma cells transplanted in mice

    Directory of Open Access Journals (Sweden)

    Eman I. Abdel-Gawad

    2016-01-01

    Full Text Available The present study aimed to investigate the mode of action of nano-CaPs in vivo as a therapy for solid tumor in mice. To achieve this goal, Ehrlich Ascites Carcinoma (EAC was transplanted into 85 Swiss male albino mice. After nine days, the mice were divided into 9 groups. Groups 1 and 2 were allocated as the EAC control. Groups 3 and 4 were injected once intratumorally (IT by nano-calcium phosphate (nano-CaP. Groups 5 and 6 received once intraperitoneal injection (IP of nano-CaP. Groups 7, 8, and 9 received nano-CaP (IP weekly. Blood samples and thigh skeletal muscle were collected after three weeks from groups 1, 3, 5, and 7 and after four weeks from groups 2, 4, 6, and 8. On the other hand, group 9 received nano-CaP (IP for four weeks and lasted for three months to follow up the recurrence of tumor and to ensure the safety of muscle by histopathological analysis. Tumor growth was monitored twice a week throughout the experiment. DNA fragmentation of tumor cells was evaluated. In thigh tissue, noradrenaline, dopamine, serotonin (5HT, and gamma-aminobutyric acid (GABA were measured. In serum, 8-Hydroxy-deoxyguanosine (8-OHDG, adenosine triphosphate (ATP, and vascular endothelial growth factor (VEGF were analyzed. Histopathological and biochemical results showed a significant therapeutic effect of nano-CaP on implanted solid tumor and this effect was more pronounced in the animals treated IP for four weeks. This improvement was evident from the repair of fragmented DNA, the significant decrease of caspase-3, 8-OHDG, myosin, and VEGF, and the significant increase of neurotransmitters (NA, DA, 5HT, and GABA. Additionally, histopathological examination showed complete recovery of cancer cells in the thigh muscle after three months.

  12. Targeting voltage-gated calcium channels: developments in peptide and small-molecule inhibitors for the treatment of neuropathic pain

    Science.gov (United States)

    Vink, S; Alewood, PF

    2012-01-01

    Chronic pain affects approximately 20% of people worldwide and places a large economic and social burden on society. Despite the availability of a range of analgesics, this condition is inadequately treated, with complete alleviation of symptoms rarely occurring. In the past 30 years, the voltage-gated calcium channels (VGCCs) have been recognized as potential targets for analgesic development. Although the majority of the research has been focused on Cav2.2 in particular, other VGCC subtypes such as Cav3.2 have recently come to the forefront of analgesic research. Venom peptides from marine cone snails have been proven to be a valuable tool in neuroscience, playing a major role in the identification and characterization of VGCC subtypes and producing the first conotoxin-based drug on the market, the ω-conotoxin, ziconotide. This peptide potently and selectively inhibits Cav2.2, resulting in analgesia in chronic pain states. However, this drug is only available via intrathecal administration, and adverse effects and a narrow therapeutic window have limited its use in the clinic. Other Cav2.2 inhibitors are currently in development and offer the promise of an improved route of administration and safety profile. This review assesses the potential of targeting VGCCs for analgesic development, with a main focus on conotoxins that block Cav2.2 and the developments made to transform them into therapeutics. PMID:22725651

  13. Changes in Intracellular Calcium Concentration and pH of Target Cells During the Cytotoxic Process: A Quantitative Study at the Single Cell Level

    NARCIS (Netherlands)

    de Grooth, B.G.; Radosevic, Katarina; Greve, Jan; Radosevic, K.

    1995-01-01

    This study reports on the changes in intracellular calcium concentration ([Ca2+]in) and intracellular pH ([pH]in) that occur in K562 target cells during interaction with human Natural Killer (NK) cells. The data were obtained using a quantitative fluorescence microscope and fluorescent ratio probes

  14. 48 CFR 16.403-2 - Fixed-price incentive (successive targets) contracts.

    Science.gov (United States)

    2010-10-01

    ... target cost plus the firm target profit as a guide. (ii) If negotiation of a firm fixed price is... pricing information is not sufficient to permit the negotiation of a realistic firm target cost and profit...; and (2) Cost or pricing information adequate for establishing a reasonable firm target cost is...

  15. Calcium-activated potassium channels - a therapeutic target for modulating nitric oxide in cardiovascular disease?

    DEFF Research Database (Denmark)

    Dalsgaard, Thomas; Kroigaard, Christel; Simonsen, Ulf

    2010-01-01

    IMPORTANCE OF THE FIELD: Cardiovascular risk factors are often associated with endothelial dysfunction, which is also prognostic for occurrence of cardiovascular events. Endothelial dysfunction is reflected by blunted vasodilatation and reduced nitric oxide (NO) bioavailability. Endothelium......-dependent vasodilatation is mediated by NO, prostacyclin, and an endothelium-derived hyperpolarising factor (EDHF), and involves small (SK) and intermediate (IK) conductance Ca(2+)-activated K(+) channels. Therefore, SK and IK channels may be drug targets for the treatment of endothelial dysfunction in cardiovascular...... disease. AREAS COVERED IN THIS REVIEW: SK and IK channels are involved in EDHF-type vasodilatation, but recent studies suggest that these channels are also involved in the regulation of NO bioavailability. Here we review how SK and IK channels may regulate NO bioavailability. WHAT THE READER WILL GAIN...

  16. Targeted Temperature Management for 48 vs 24 Hours and Neurologic Outcome After Out-of-Hospital Cardiac Arrest

    DEFF Research Database (Denmark)

    Kirkegaard, Hans; Søreide, Eldar; de Haas, Inge

    2017-01-01

    hours results in better neurologic outcomes compared with currently recommended, standard, 24-hour TTM. Design, Setting, and Participants: This was an international, investigator-initiated, blinded-outcome-assessor, parallel, pragmatic, multicenter, randomized clinical superiority trial in 10 intensive...... (33 ± 1°C) for 48 hours (n = 176) or 24 hours (n = 179), followed by gradual rewarming of 0.5°C per hour until reaching 37°C. Main Outcomes and Measures: The primary outcome was 6-month neurologic outcome, with a Cerebral Performance Categories (CPC) score of 1 or 2 used to define favorable outcome......: In unconscious survivors from out-of-hospital cardiac arrest admitted to the ICU, targeted temperature management at 33°C for 48 hours did not significantly improve 6-month neurologic outcome compared with targeted temperature management at 33°C for 24 hours. However, the study may have had limited power...

  17. Comparison of Calcium Dynamics and Specific Features for G Protein-Coupled Receptor-Targeting Drugs Using Live Cell Imaging and Automated Analysis.

    Science.gov (United States)

    Gupta, Rishikesh Kumar; Swain, Sarpras; Kankanamge, Dinesh; Priyanka, Pantula Devi; Singh, Ranjana; Mitra, Kishalay; Karunarathne, Ajith; Giri, Lopamudra

    2017-08-01

    G protein-coupled receptors (GPCRs) are targets for designing a large fraction of the drugs in the pharmaceutical industry. For GPCR-targeting drug screening using cell-based assays, measurement of cytosolic calcium has been widely used to obtain dose-response profiles. However, it remains challenging to obtain drug-specific features due to cell-to-cell heterogeneity in drug-cell responses obtained from live cell imaging. Here, we present a framework combining live cell imaging of a cell population and a feature extraction method for classification of responses of drugs targeting GPCRs CXCR4 and α2AR. We measured the calcium dynamics using confocal microscopy and compared the responses for SDF-1α and norepinephrine. The results clearly show that the clustering patterns of responses for the two GPCRs are significantly different. Additionally, we show that different drugs targeting the same GPCR induce different calcium response signatures. We also implemented principal component analysis and k means for feature extraction and used nondominated (ND) sorting for ranking a group of drugs at various doses. The presented approach can be used to model a cell population as a mixture of subpopulations. It also offers specific advantages, such as higher spatial resolution, classification of responses, and ranking of drugs, potentially providing a platform for high-content drug screening.

  18. 48 CFR 952.226-71 - Utilization of Energy Policy Act target entities.

    Science.gov (United States)

    2010-10-01

    ... the following clause: Utilization of Energy Policy Act Target Entities (JUN 1996) (a) Definition. Energy Policy Act target groups, as used in this provision means: (1) An institution of higher education..., Eskimos, Aleuts, and Native Hawaiians, or any combination thereof; (2) Institutions of higher learning...

  19. The Cry48Aa-Cry49Aa binary toxin from Bacillus sphaericus exhibits highly restricted target specificity.

    Science.gov (United States)

    Jones, Gareth W; Wirth, Margaret C; Monnerat, Rose G; Berry, Colin

    2008-09-01

    The Cry48Aa/Cry49Aa binary toxin of Bacillus sphaericus was recently discovered by its ability to kill Culex quinquefasciatus mosquito larvae through a novel interaction between its two components. We have investigated the target specificity of this toxin and show it to be non-toxic to coleopteran, lepidopteran and other dipteran insects, including closely related Aedes and Anopheles mosquitoes. This represents an unusually restricted target range for crystal toxins from either B. sphaericus or Bacillus thuringiensis. Gut extracts from Culex and Aedes larvae show differential processing of the Cry48Aa protein, with the location of cleavage sites in Culex reflecting those previously shown for the activation of Cry4 toxins in mosquitoes. Pre-activation of Cry48Aa/Cry49Aa with Culex extracts, however, fails to induce toxicity to Aedes larvae. Co-administration of Cry49Aa with Cry4Aa gives higher than predicted toxicity, perhaps suggesting weak synergism against Culex larvae between Cry49Aa and other three-domain Cry toxins.

  20. Development and implementation of a high-throughput compound screening assay for targeting disrupted ER calcium homeostasis in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Kamran Honarnejad

    Full Text Available Disrupted intracellular calcium homeostasis is believed to occur early in the cascade of events leading to Alzheimer's disease (AD pathology. Particularly familial AD mutations linked to Presenilins result in exaggerated agonist-evoked calcium release from endoplasmic reticulum (ER. Here we report the development of a fully automated high-throughput calcium imaging assay utilizing a genetically-encoded FRET-based calcium indicator at single cell resolution for compound screening. The established high-throughput screening assay offers several advantages over conventional high-throughput calcium imaging technologies. We employed this assay for drug discovery in AD by screening compound libraries consisting of over 20,000 small molecules followed by structure-activity-relationship analysis. This led to the identification of Bepridil, a calcium channel antagonist drug in addition to four further lead structures capable of normalizing the potentiated FAD-PS1-induced calcium release from ER. Interestingly, it has recently been reported that Bepridil can reduce Aβ production by lowering BACE1 activity. Indeed, we also detected lowered Aβ, increased sAPPα and decreased sAPPβ fragment levels upon Bepridil treatment. The latter findings suggest that Bepridil may provide a multifactorial therapeutic modality for AD by simultaneously addressing multiple aspects of the disease.

  1. Congenital heart block maternal sera autoantibodies target an extracellular epitope on the α1G T-type calcium channel in human fetal hearts.

    Directory of Open Access Journals (Sweden)

    Linn S Strandberg

    Full Text Available BACKGROUND: Congenital heart block (CHB is a transplacentally acquired autoimmune disease associated with anti-Ro/SSA and anti-La/SSB maternal autoantibodies and is characterized primarily by atrioventricular (AV block of the fetal heart. This study aims to investigate whether the T-type calcium channel subunit α1G may be a fetal target of maternal sera autoantibodies in CHB. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate differential mRNA expression of the T-type calcium channel CACNA1G (α1G gene in the AV junction of human fetal hearts compared to the apex (18-22.6 weeks gestation. Using human fetal hearts (20-22 wks gestation, our immunoprecipitation (IP, Western blot analysis and immunofluorescence (IF staining results, taken together, demonstrate accessibility of the α1G epitope on the surfaces of cardiomyocytes as well as reactivity of maternal serum from CHB affected pregnancies to the α1G protein. By ELISA we demonstrated maternal sera reactivity to α1G was significantly higher in CHB maternal sera compared to controls, and reactivity was epitope mapped to a peptide designated as p305 (corresponding to aa305-319 of the extracellular loop linking transmembrane segments S5-S6 in α1G repeat I. Maternal sera from CHB affected pregnancies also reacted more weakly to the homologous region (7/15 amino acids conserved of the α1H channel. Electrophysiology experiments with single-cell patch-clamp also demonstrated effects of CHB maternal sera on T-type current in mouse sinoatrial node (SAN cells. CONCLUSIONS/SIGNIFICANCE: Taken together, these results indicate that CHB maternal sera antibodies readily target an extracellular epitope of α1G T-type calcium channels in human fetal cardiomyocytes. CHB maternal sera also show reactivity for α1H suggesting that autoantibodies can target multiple fetal targets.

  2. 20-O-β-d-glucopyranosyl-20(S)-protopanaxadiol, a metabolite of ginseng, inhibits colon cancer growth by targeting TRPC channel-mediated calcium influx.

    Science.gov (United States)

    Hwang, Jeong Ah; Hwang, Mun Kyung; Jang, Yongwoo; Lee, Eun Jung; Kim, Jong-Eun; Oh, Mi Hyun; Shin, Dong Joo; Lim, Semi; Ji, Geun og; Oh, Uhtaek; Bode, Ann M; Dong, Zigang; Lee, Ki Won; Lee, Hyong Joo

    2013-06-01

    Abnormal regulation of Ca(2+) mediates tumorigenesis and Ca(2+) channels are reportedly deregulated in cancers, indicating that regulating Ca(2+) signaling in cancer cells is considered as a promising strategy to treat cancer. However, little is known regarding the mechanism by which Ca(2+) affects cancer cell death. Here, we show that 20-O-β-d-glucopyranosyl-20(S)-protopanaxadiol (20-GPPD), a metabolite of ginseng saponin, causes apoptosis of colon cancer cells through the induction of cytoplasmic Ca(2+). 20-GPPD decreased cell viability, increased annexin V-positive early apoptosis and induced sub-G1 accumulation and nuclear condensation of CT-26 murine colon cancer cells. Although 20-GPPD-induced activation of AMP-activated protein kinase (AMPK) played a key role in the apoptotic death of CT-26 cells, LKB1, a well-known upstream kinase of AMPK, was not involved in this activation. To identify the upstream target of 20-GPPD for activating AMPK, we examined the effect of Ca(2+) on apoptosis of CT-26 cells. A calcium chelator recovered 20-GPPD-induced AMPK phosphorylation and CT-26 cell death. Confocal microscopy showed that 20-GPPD increased Ca(2+) entry into CT-26 cells, whereas a transient receptor potential canonical (TRPC) blocker suppressed Ca(2+) entry. When cells were treated with a TRPC blocker plus an endoplasmic reticulum (ER) calcium blocker, 20-GPPD-induced calcium influx was completely inhibited, suggesting that the ER calcium store, as well as TRPC, was involved. In vivo mouse CT-26 allografts showed that 20-GPPD significantly suppressed tumor growth, volume and weight in a dose-dependent manner. Collectively, 20-GPPD exerts potent anticarcinogenic effects on colon carcinogenesis by increasing Ca(2+) influx, mainly through TRPC channels, and by targeting AMPK. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

  4. Fe-bLf nanoformulation targets survivin to kill colon cancer stem cells and maintains absorption of iron, calcium and zinc.

    Science.gov (United States)

    Kanwar, Jagat R; Mahidhara, Ganesh; Roy, Kislay; Sasidharan, Sreenivasan; Krishnakumar, Subramanian; Prasad, Neerati; Sehgal, Rakesh; Kanwar, Rupinder K

    2015-01-01

    To validate the anticancer efficacy of alginate-enclosed, chitosan-conjugated, calcium phosphate, iron-saturated bovine lactoferrin (Fe-bLf) nanocarriers/nanocapsules (NCs) with improved sustained release and ability to induce apoptosis by downregulating survivin, as well as cancer stem cells. The stability, nanotoxicity of the modified nanoformulation was evaluated and their anticancer efficacy was re-examined. Their mechanism of internalization was studied and we identified the role of various miRNAs in absorption of these NCs/iron in various body parts of mice. We determined the effect of these NCs on survivin, stem cell markers, red blood cell count, iron, calcium and zinc concentration in mice, determined the antiangiogenic properties of these NCs and studied their effect on cancer stem-like cells. Spherical NCs (396.1 ± 27.2 nm) exceedingly reduced viability of Caco-2 cells (32 ± 2.83%). The NCs also showed effective internalization and reduction of cancer stem cell markers in triple-positive CD133, survivin and CD44 cancer stem-like cells. Mice treated with the NCs showed no nanotoxicity and did not develop any tumors in xenograft colon cancer models. We found that the serum iron, zinc and calcium absorption were increased. DMT1, LRP, transferrin and lactoferrin receptors were responsible for internalization of the NCs. Different miRNAs were responsible for iron regulation in different organs. Interestingly, NCs inhibited survivin and its different isoforms. Our results confirmed that NCs internalized and changed the expression of selected miRNAs that further enhanced their uptake. The NCs activated both extrinsic, as well as intrinsic apoptotic pathways to induce apoptosis by targeting survivin in cancer cells and cancer stem cells, without inducing any nonspecific nanotoxicity. Apart from inhibiting angiogenesis and stem cell markers, NCs also maintained iron and calcium levels.

  5. Effect of insecticidal fusion proteins containing spider toxins targeting sodium and calcium ion channels on pyrethroid-resistant strains of peach-potato aphid (Myzus persicae).

    Science.gov (United States)

    Yang, Sheng; Fitches, Elaine; Pyati, Prashant; Gatehouse, John A

    2015-07-01

    The recombinant fusion proteins Pl1a/GNA and Hv1a/GNA contain the spider venom peptides δ-amaurobitoxin-PI1a or ω-hexatoxin-Hv1a respectively, linked to snowdrop lectin (GNA). Pl1a targets receptor site 4 of insect voltage-gated sodium channels (NaCh), while Hv1a targets voltage-gated calcium channels. Insecticide-resistant strains of peach-potato aphid (Myzus persicae) contain mutations in NaCh. The pyrethroid-resistant kdr (794J) and super-kdr (UKO) strains contain mutations at residues L1014 and M918 in the channel α-subunit respectively, while the kdr + super-kdr strain (4824J), insensitive to pyrethroids, contains mutations at both L1014 and M918. Pl1a/GNA and Hv1a/GNA fusion proteins have estimated LC50 values of 0.35 and 0.19 mg mL(-1) when fed to wild-type M. persicae. For insecticide-resistant aphids, LC50 for the Pl1a/GNA fusion protein increased by 2-6-fold, correlating with pyrethroid resistance (wild type < kdr < super-kdr < kdr + super-kdr strains). In contrast, LC50 for the Hv1a/GNA fusion protein showed limited correlation with pyrethroid resistance. Mutations in the sodium channel in pyrethroid-resistant aphids also protect against a fusion protein containing a sodium-channel-specific toxin, in spite of differences in ligand-channel interactions, but do not confer resistance to a fusion protein targeting calcium channels. The use of fusion proteins with differing targets could play a role in managing pesticide resistance. © 2014 Society of Chemical Industry.

  6. Targeting Intracellular Calcium Signaling ([Ca2+]i to Overcome Acquired Multidrug Resistance of Cancer Cells: A Mini-Overview

    Directory of Open Access Journals (Sweden)

    Dietrich Büsselberg

    2017-05-01

    Full Text Available Cancer is a main public health problem all over the world. It affects millions of humans no matter their age, gender, education, or social status. Although chemotherapy is the main strategy for the treatment of cancer, a major problem limiting its success is the intrinsic or acquired drug resistance. Therefore, cancer drug resistance is a major impediment in medical oncology resulting in a failure of a successful cancer treatment. This mini-overview focuses on the interdependent relationship between intracellular calcium ([Ca2+]i signaling and multidrug resistance of cancer cells, acquired upon treatment of tumors with anticancer drugs. We propose that [Ca2+]i signaling modulates gene expression of multidrug resistant (MDR genes which in turn can be modulated by epigenetic factors which in turn leads to modified protein expression in drug resistant tumor cells. A precise knowledge of these mechanisms will help to develop new therapeutic strategies for drug resistant tumors and will improve current chemotherapy.

  7. Calcium Carbonate

    Science.gov (United States)

    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 ...

  8. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  9. Rice calcium-dependent protein kinase OsCPK17 targets plasma membrane intrinsic protein and sucrose phosphate synthase and is required for a proper cold stress response

    KAUST Repository

    Almadanim, M. Cecília

    2017-01-19

    Calcium-dependent protein kinases (CDPKs) are involved in plant tolerance mechanisms to abiotic stresses. Although CDPKs are recognized as key messengers in signal transduction, the specific role of most members of this family remains unknown. Here we test the hypothesis that OsCPK17 plays a role in rice cold stress response by analyzing OsCPK17 knockout, silencing, and overexpressing rice lines under low temperature. Altered OsCPK17 gene expression compromises cold tolerance performance, without affecting the expression of key cold stress-inducible genes. A comparative phosphoproteomic approach led to the identification of six potential in vivo OsCPK17 targets, which are associated with sugar and nitrogen metabolism, and with osmotic regulation. To test direct interaction, in vitro kinase assays were performed, showing that the sucrose phosphate synthase OsSPS4, and the aquaporin OsPIP2;1/OsPIP2;6 are phosphorylated by OsCPK17 in a calcium-dependent manner. Altogether, our data indicates that OsCPK17 is required for a proper cold stress response in rice, likely affecting the activity of membrane channels and sugar metabolism.

  10. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  11. Vinculin but not alpha-actinin is a target of PKC phosphorylation during junctional assembly induced by calcium

    DEFF Research Database (Denmark)

    Perez-Moreno, M; Avila, A; Islas, S

    1998-01-01

    proteins ZO1, ZO2 and ZO3, in a previous work we specifically explored these molecules but found no alteration in their phosphorylation pattern. To continue the search for the target of protein kinase C, in the present work we have studied the subcellular distribution and phosphorylation of vinculin...

  12. Bcl-2 regulation of the inositol 1,4,5-trisphosphate receptor and calcium signaling in normal and malignant lymphocytes: potential new target for cancer treatment.

    Science.gov (United States)

    Greenberg, Edward F; Lavik, Andrew R; Distelhorst, Clark W

    2014-10-01

    The anti-apoptotic protein Bcl-2 is a versatile regulator of cell survival. Its interactions with its own pro-apoptotic family members are widely recognized for their role in promoting the survival of cancer cells. These interactions are thus being targeted for cancer treatment. Less widely recognized is the interaction of Bcl-2 with the inositol 1,4,5-trisphosphate receptor (InsP3R), an InsP3-gated Ca(2+) channel located on the endoplasmic reticulum. The nature of this interaction, the mechanism by which it controls Ca(2+) release from the ER, its role in T-cell development and survival, and the possibility of targeting it as a novel cancer treatment strategy are summarized in this review. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Antimicrobial peptaibols, novel suppressors of tumor cells, targeted calcium-mediated apoptosis and autophagy in human hepatocellular carcinoma cells

    Directory of Open Access Journals (Sweden)

    Chen Xiu-Lan

    2010-02-01

    Full Text Available Abstract Background Hepatocellular carcinoma (HCC is one of the most common cancers in the world which is highly chemoresistant to currently available chemotherapeutic agents. Thus, novel therapeutic targets are needed to be sought for the successful treatment of HCC. Peptaibols, a family of peptides synthesized non-ribosomally by the Trichoderma species and other fungi, exhibit antibiotic activities against bacteria and fungi. Few studies recently showed that peptaibols exerted cytotoxicity toward human lung epithelial and breast carcinoma cells. However, the mechanism involved in peptaibol-induced cell death remains poorly understood. Results Here, we showed that Trichokonin VI (TK VI, a peptaibol from Trichoderma pseudokoningii SMF2, induced growth inhibition of HCC cells in a dose-dependent manner. It did not obviously impair the viability of normal liver cells at lower concentration. Moreover, the suppression of cell viability resulted from the programmed cell death (PCD with characteristics of apoptosis and autophagy. An influx of Ca2+ triggered the activation of μ-calpain and proceeded to the translocation of Bax to mitochondria and subsequent promotion of apoptosis. On the other hand, typically morphological characteristics consistent with autophagy were also observed by punctate distribution of MDC staining and the induction of LC3-II, including extensive autophagic vacuolization and enclosure of cell organelles by these autophagosomes. More significantly, specific depletion of Bak expression by small RNA interfering (siRNA could partly attenuate TK VI-induced autophagy. However, siRNA against Bax led to increased autophagy. Conclusion Taken together, these findings showed for the first time that peptaibols were novel regulators involved in both apoptosis and autophagy, suggesting that the class of peptaibols might serve as potential suppressors of tumor cells.

  14. Gene-Targeted Mice with the Human Troponin T R141W Mutation Develop Dilated Cardiomyopathy with Calcium Desensitization.

    Directory of Open Access Journals (Sweden)

    Mohun Ramratnam

    Full Text Available Most studies of the mechanisms leading to hereditary dilated cardiomyopathy (DCM have been performed in reconstituted in vitro systems. Genetically engineered murine models offer the opportunity to dissect these mechanisms in vivo. We generated a gene-targeted knock-in murine model of the autosomal dominant Arg141Trp (R141W mutation in Tnnt2, which was first described in a human family with DCM. Mice heterozygous for the mutation (Tnnt2R141W/+ recapitulated the human phenotype, developing left ventricular dilation and reduced contractility. There was a gene dosage effect, so that the phenotype in Tnnt2R141W/+mice was attenuated by transgenic overexpression of wildtype Tnnt2 mRNA transcript. Male mice exhibited poorer survival than females. Biomechanical studies on skinned fibers from Tnnt2R141W/+ hearts showed a significant decrease in pCa50 (-log[Ca2+] required for generation of 50% of maximal force relative to wildtype hearts, indicating Ca2+ desensitization. Optical mapping studies of Langendorff-perfused Tnnt2R141W/+ hearts showed marked increases in diastolic and peak systolic intracellular Ca2+ ([Ca2+]i, and prolonged systolic rise and diastolic fall of [Ca2+]i. Perfused Tnnt2R141W/+ hearts had slower intrinsic rates in sinus rhythm and reduced peak heart rates in response to isoproterenol. Tnnt2R141W/+ hearts exhibited a reduction in phosphorylated phospholamban relative to wildtype mice. However, crossing Tnnt2R141W/+ mice with phospholamban knockout (Pln-/- mice, which exhibit increased Ca2+ transients and contractility, had no effect on the DCM phenotype. We conclude that the Tnnt2 R141W mutation causes a Ca2+ desensitization and mice adapt by increasing Ca2+-transient amplitudes, which impairs Ca2+ handling dynamics, metabolism and responses to β-adrenergic activation.

  15. On the quest of production of superheavy nuclei in reactions of {sup 48}Ca with the heaviest actinide targets

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P.

    1999-10-01

    The sequence of radioactive decays of an unknown isotope produced in a rare fusion reaction to known lighter isotopes is used to identify mass and atomic number of the mother isotope, which has been separated before from the bulk of other reaction products by an in-flight recoil separator. By this technique the elements 107 to 112 were produced by single atom decay-chain analysis. Such a correlation technique reaches its limit by the occurrence of accidental sequences and it collapses beyond a maximum possible correlation time, at which a true event cannot be distinguished anymore from a random event. {sup 48}Ca-induced fusion reactions with actinides are discussed. In 1983 at GSI, Darmstadt and LBL, Berkeley, {sup 48}Ca/{sup 248}Cm-experiments (II) were performed, which are compared to recent {sup 48}Ca-experiments at FLNR-Dubna (I) irradiating {sup 244}Pu, {sup 242}Pu, and {sup 238}U. In these experiments production of isotopes of superheavy elements 112 and 114 is claimed. Our analysis of accidental sequences in {sup 48}Ca-induced reactions is presented, which is at variance with the published analysis from FLNR-Dubna. We find that the maximum correlation time using continuous beams at today existing separation systems is not in the one-hour regime, but in the few-minute regime. The five spontaneous fission events observed in the FLNR experiments are preceded by signals in the (1-16)-minute range. These times are shown to be longer than the maximum possible correlation times. The preceding signals are decoupled from the spontaneous fission signal and carry no information on the spontaneous fission events observed. Moreover, random probabilities of 0.2 to 0.6 for the signals preceding the fission events indicate that the correlations are of random origin. The evidence to have discovered element 114 in the reported experiments is classified ''very weak''. (orig.)

  16. Cyclotron Produced 44gSc from Natural Calcium

    Science.gov (United States)

    Severin, G.W.; Engle, J.W.; Valdovinos, H.F.; Barnhart, T.E.; Nickles, R.J.

    2012-01-01

    44gSc was produced by 16 MeV proton irradiation of unenriched calcium metal with radionuclidic purity greater than 95%. The thick target yield at saturation for 44gSc was 213 MBq/μA, dwarfing the yields of contaminants 43Sc,44mSc, 47Sc and 48Sc for practical bombardment times of 1–2 h. Scandium was isolated from the dissolved calcium target by filtration, and reconstituted in small volumes of dilute HCl. Reactions with the chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) indicated a reactivity of 54±14 Gbq/μmol at end-of-bombardment. PMID:22728844

  17. Gualou Guizhi decoction reverses brain damage with cerebral ischemic stroke, multi-component directed multi-target to screen calcium-overload inhibitors using combination of molecular docking and protein-protein docking.

    Science.gov (United States)

    Hu, Juan; Pang, Wen-Sheng; Han, Jing; Zhang, Kuan; Zhang, Ji-Zhou; Chen, Li-Dian

    2018-12-01

    Stroke is a disease of the leading causes of mortality and disability across the world, but the benefits of drugs curative effects look less compelling, intracellular calcium overload is considered to be a key pathologic factor for ischemic stroke. Gualou Guizhi decoction (GLGZD), a classical Chinese medicine compound prescription, it has been used to human clinical therapy of sequela of cerebral ischemia stroke for 10 years. This work investigated the GLGZD improved prescription against intracellular calcium overload could decreased the concentration of [Ca2+]i in cortex and striatum neurone of MCAO rats. GLGZD contains Trichosanthin and various small molecular that they are the potential active ingredients directed against NR2A, NR2B, FKBP12 and Calnodulin target proteins/enzyme have been screened by computer simulation. "Multicomponent systems" is capable to create pharmacological superposition effects. The Chinese medicine compound prescriptions could be considered as promising sources of candidates for discovery new agents.

  18. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  19. Paclitaxel induces apoptosis in breast cancer cells through different calcium--regulating mechanisms depending on external calcium conditions.

    Science.gov (United States)

    Pan, Zhi; Avila, Andrew; Gollahon, Lauren

    2014-02-17

    Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and/or was necessary for paclitaxel-induced apoptosis. Our results demonstrated that paclitaxel induced extracellular calcium influx. This mobilization of extracellular calcium contributed to subsequent cytosolic calcium elevation differently, depending on dosage. Under normal extracellular calcium conditions, high dose paclitaxel induced apoptosis-promoting calcium influx, which did not occur in calcium-free conditions. In the absence of extracellular calcium an "Enhanced Calcium Efflux" mechanism in which high dose paclitaxel stimulated calcium efflux immediately, leading to dramatic cytosolic calcium decrease, was observed. In the absence of extracellular calcium, high dose paclitaxel's stimulatory effects on capacitative calcium entry and apoptosis could not be completely restored. Thus, normal extracellular calcium concentrations are critical for high dose paclitaxel-induced apoptosis. In contrast, low dose paclitaxel mirrored controls, indicating that it occurs independent of extracellular calcium. Thus, extracellular calcium conditions only affect efficacy of high dose paclitaxel-induced apoptosis.

  20. X-ray emission analysis of a plasma source using an yttrium and a mylar target for the generation of 2.48 nm wavelength microbeam

    Energy Technology Data Exchange (ETDEWEB)

    Palladino, Libero; Lorenzo, Ramon Gimenez De; Emilio, Maurizio Di Paolo [Dipartimento di Fisica, Universita’ de L’Aquila (Italy); INFN, Laboratorio Nazionale del Gran Sasso, Assergi (AQ) (Italy); Limongi, Tania, E-mail: tania.limongi@gmail.com [Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy)

    2013-05-01

    In this work, the characteristics of X-ray beam generated from a plasma produced by focusing a Nd-Yag/glass laser beam on mylar or yttrium target were presented. For each target material, the conversion efficiencies of the soft X-ray emission in two different energy ranges, (i) 300–510 eV (almost coincident with the Water Window), (ii) 450–850 eV were measured. The experimental results of the conversion efficiencies will be utilized at the PLASMA-X laboratory of L’Aquila University for the realization of an intense monochromatic X-ray microbeam to be used in radiobiological and in transmission X-ray microscopy applications. In the presented experimental set-up, at the wavelength of 2.48 nm, a monochromatic soft X-rays beam was collected by multilayer spherical mirrors reflecting at an incidence angle close to the normal of the surface. The optical system geometry, the monochromatic beam intensity and the measures of efficiency of conversion of X-ray were described in this paper [5].

  1. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  2. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  3. Production cross sections of elements near the N=126 shell in Ca48-induced reactions with Gd154,Tb159,Dy162, and Ho165 targets

    Science.gov (United States)

    Mayorov, D. A.; Werke, T. A.; Alfonso, M. C.; Bennett, M. E.; Folden, C. M.

    2014-08-01

    Excitation functions for shell-stabilized evaporation residues produced in Ca48-induced reactions with Gd154,Tb159,Dy162, and Ho165 targets have been measured in experiments performed at the Cyclotron Institute at Texas A&M University. The examined energy range predominantly covers the 3n and 4n evaporation channels with higher cross sections measured for the 4n products. The σ4n are nearly invariant within experimental uncertainty in reactions with Tb159,Dy162, and Ho165 with the maxima at 12.6 ± 1.9, 12.6 ± 1.7, and 9.4 ± 1.3 mb, respectively. For the reaction with Gd154, the maximum is slightly lower at 4.0 ± 0.6 mb. A simple model to describe the measured production cross sections was employed. Capture was estimated by using the "diffused barrier formula" from the "fusion by diffusion" model proposed by Świątecki et al. [Phys. Rev. C 71, 014602 (2005)]., 10.1103/PhysRevC.71.014602 The fusion probability was estimated by using a phenomenological expression presented by Siwek-Wilczyńska et al. [Int. J. Mod. Phys. E 17, 12 (2008)]., 10.1142/S0218301308009501 The survival probability was calculated according to the formula of Vandenbosch and Huizenga [Nuclear Fission (Academic, New York, 1973)], derived from transition-state theory. The best agreement is reached between calculation and experiment upon inclusion of collective effects in the calculation of the survival probability, shown previously to be important for production of weakly deformed nuclei. This, in turn, challenges the expectation that strong shell stabilization benefits the production cross section. The present data are compared with earlier studies on production of neutron-deficient nuclei in Ca-induced reactions with lanthanide targets.

  4. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  5. Rice calcium-dependent protein kinase OsCPK17 targets plasma membrane intrinsic protein and sucrose-phosphate synthase and is required for a proper cold stress response.

    Science.gov (United States)

    Almadanim, M Cecília; Alexandre, Bruno M; Rosa, Margarida T G; Sapeta, Helena; Leitão, António E; Ramalho, José C; Lam, TuKiet T; Negrão, Sónia; Abreu, Isabel A; Oliveira, M Margarida

    2017-07-01

    Calcium-dependent protein kinases (CDPKs) are involved in plant tolerance mechanisms to abiotic stresses. Although CDPKs are recognized as key messengers in signal transduction, the specific role of most members of this family remains unknown. Here, we test the hypothesis that OsCPK17 plays a role in rice cold stress response by analysing OsCPK17 knockout, silencing and overexpressing rice lines under low temperature. Altered OsCPK17 gene expression compromises cold tolerance performance, without affecting the expression of key cold stress-inducible genes. A comparative phosphoproteomic approach led to the identification of six potential in vivo OsCPK17 targets, which are associated with sugar and nitrogen metabolism, and with osmotic regulation. To test direct interaction, in vitro kinase assays were performed, showing that the sucrose-phosphate synthase OsSPS4 and the aquaporin OsPIP2;1/OsPIP2;6 are phosphorylated by OsCPK17 in a calcium-dependent manner. Altogether, our data indicates that OsCPK17 is required for a proper cold stress response in rice, likely affecting the activity of membrane channels and sugar metabolism. © 2017 John Wiley & Sons Ltd.

  6. Separation of no-carrier-added {sup 203}Pb, a surrogate radioisotope, from proton irradiated {sup nat}Tl{sub 2}CO{sub 3} target using calcium alginate hydrogel beads

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Kangkana; Sen, Kamalika [Univ. of Calcutta, Kolkata (India). Dept. of Chemistry; Lahiri, Susanta [Saha Institute of Nuclear Physics, Kolkata (India)

    2016-07-01

    {sup 203}Pb is a promising radioisotope in the field of medical science as an imaging surrogate of {sup 212}Pb. In the present investigation {sup 203}Pb was produced by proton irradiation of natural Tl{sub 2}CO{sub 3} target and was separated from the bulk Tl target using calcium alginate (CA) hydrogel beads with a high separation factor (3.8 x 10{sup 4} at 10{sup -3} M HNO{sub 3}). During the separation process {sup 203}Pb was encapsulated in CA beads and desorption of the radioisotope could only be achieved in 1M HNO{sub 3}. Possibility of Tl uptake was also checked in Fe doped CA (Fe-CA) beads after oxidation of Tl(I) to Tl(III) by sodium bismuthate. No significant uptake of Tl(III) was noticed in the Fe-CA beads. The matrix is therefore suitable for isolation of {sup 203}Pb from the target as well as its storage in the bead for therapeutic as well as diagnostic purpose.

  7. Temperature-Sensitive Cav1.2 Calcium Channels Support Intrinsic Firing of Pyramidal Neurons and Provide a Target for the Treatment of Febrile Seizures

    Science.gov (United States)

    Radzicki, Daniel; Yau, Hau-Jie; Pollema-Mays, Sarah L.; Mlsna, Lauren; Cho, Kangho; Koh, Sookyong

    2013-01-01

    Febrile seizures are associated with increased brain temperature and are often resistant to treatments with antiepileptic drugs, such as carbamazepine and phenytoin, which are sodium channel blockers. Although they are clearly correlated with the hyperthermic condition, the precise cellular mechanisms of febrile seizures remain unclear. We performed patch-clamp recordings from pyramidal cells in acute rat brain slices at temperatures up to 40°C and found that, at ≥37°C, L-type calcium channels are active at unexpectedly hyperpolarized potentials and drive intrinsic firing, which is also supported by a temperature-dependent, gadolinium-sensitive sodium conductance. Pharmacological data, RT-PCR, and the current persistence in Cav1.3 knock-out mice suggested a critical contribution of Cav1.2 subunits to the temperature-dependent intrinsic firing, which was blocked by nimodipine. Because intrinsic firing may play a critical role in febrile seizures, we tested the effect of nimodipine in an in vivo model of febrile seizures and found that this drug dramatically reduces both the incidence and duration of febrile seizures in rat pups, suggesting new possibilities of intervention for this important pathological condition. PMID:23761887

  8. Coronary Calcium Scan

    Science.gov (United States)

    ... Back To Health Topics / Coronary Calcium Scan Coronary Calcium Scan Also known as Calcium Scan Test A coronary calcium scan is a CT scan of your heart that detects and measures the amount of calcium in the walls of your coronary arteries. Overview ...

  9. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  10. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  11. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  12. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  13. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  14. Enhanced expression of a calcium-dependent protein kinase from ...

    Indian Academy of Sciences (India)

    Among the downstream targets of calcium in plants, calcium-dependent protein kinases (CDPKs) form an interesting class of kinases which are activated by calcium binding. They have been implicated in a diverse array of responses to hormonal and environmental stimuli. In order to dissect the role of CDPKs in the moss ...

  15. Altered calcium signaling in cancer cells.

    Science.gov (United States)

    Stewart, Teneale A; Yapa, Kunsala T D S; Monteith, Gregory R

    2015-10-01

    It is the nature of the calcium signal, as determined by the coordinated activity of a suite of calcium channels, pumps, exchangers and binding proteins that ultimately guides a cell's fate. Deregulation of the calcium signal is often deleterious and has been linked to each of the 'cancer hallmarks'. Despite this, we do not yet have a full understanding of the remodeling of the calcium signal associated with cancer. Such an understanding could aid in guiding the development of therapies specifically targeting altered calcium signaling in cancer cells during tumorigenic progression. Findings from some of the studies that have assessed the remodeling of the calcium signal associated with tumorigenesis and/or processes important in invasion and metastasis are presented in this review. The potential of new methodologies is also discussed. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Diagnostic Phase of Calcium Scoring Scan Applied as the Center of Acquisition Window of Coronary Computed Tomography Angiography Improves Image Quality in Minimal Acquisition Window Scan (Target CTA Mode Using the Second Generation 320-Row CT

    Directory of Open Access Journals (Sweden)

    Eriko Maeda

    2016-01-01

    Full Text Available Objective. To compare the image quality of coronary computed tomography angiography (CCTA acquired under two conditions: 75% fixed as the acquisition window center (Group 75% and the diagnostic phase for calcium scoring scan as the center (CS; Group CS. Methods. 320-row cardiac CT with a minimal acquisition window (scanned using “Target CTA” mode was performed on 81 patients. In Group 75% (n = 40, CS was obtained and reconstructed at 75% and the center of the CCTA acquisition window was set at 75%. In Group CS (n = 41, CS was obtained at 75% and the diagnostic phase showing minimal artifacts was applied as the center of the CCTA acquisition window. Image quality was evaluated using a four-point scale (4-excellent and the mean scores were compared between groups. Results. The CCTA scan diagnostic phase occurred significantly earlier in CS (75.7 ± 3.2% vs. 73.6 ± 4.5% for Groups 75% and CS, resp., p = 0.013. The mean Group CS image quality score (3.58 ± 0.63 was also higher than that for Group 75% (3.19 ± 0.66, p < 0.0001. Conclusions. The image quality of CCTA in Target CTA mode was significantly better when the center of acquisition window is adjusted using CS.

  17. Intracellular calcium is a target of modulation of apoptosis in MCF-7 cells in the presence of IgA adsorbed to polyethylene glycol

    Directory of Open Access Journals (Sweden)

    Honorio-França AC

    2016-02-01

    Full Text Available Adenilda Cristina Honorio-França,1 Gabriel Triches Nunes,1 Danny Laura Gomes Fagundes,1 Patrícia Gelli Feres de Marchi,1 Rubian Trindade da Silva Fernandes,1 Juliana Luzia França,1,2 Aline do Carmo França-Botelho,2 Lucélia Campelo Albuquerque Moraes,1 Fernando de Pilla Varotti,3 Eduardo Luzía França1,3 1Institute of Biological and Health Science, Federal University of Mato Grosso, Barra do Garças, Mato Grosso, Brazil; 2Institute of Health Sciences, University Center of Planalto de Araxá, Araxá, Minas Gerais, Brazil; 3Campus Centro Oeste Dona Lindu – Federal University of São João Del Rei, Divinópolis, Minas Gerais, Brazil Purpose: Clinical and epidemiological studies have indicated that breastfeeding has a protective effect on breast cancer risk. Protein-based drugs, including antibodies, are being developed to attain better forms of cancer therapy. Secretory IgA (SIgA is the antibody class in human breast milk, and its activity can be linked to the protective effect of breastfeeding. The aim of this study was to investigate the effect of polyethylene glycol (PEG microspheres with adsorbed SIgA on MCF-7 human breast cancer cells.  Methods: The PEG microspheres were characterized by flow cytometry and fluorescence microscopy. The MCF-7 cells were obtained from American Type Culture Collection. MCF-7 cells were pre-incubated for 24 hours with or without SIgA (100 ng/mL, PEG microspheres or SIgA adsorbed in PEG microspheres (100 ng/mL. Viability, intracellular calcium release, and apoptosis in MCF-7 cells were determined by flow cytometry.  Results: Fluorescence microscopy and flow cytometry analyses revealed that SIgA was able to adsorb to the PEG microspheres. The MCF-7 cells that were incubated with PEG microspheres with adsorbed SIgA showed decreased viability. MCF-7 cells that were incubated with SIgA or PEG microspheres with adsorbed SIgA had increased intracellular Ca2+ levels. In the presence of SIgA, an increase in the

  18. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    salts. The perturbation of calcium equilibria by these factors will affect the final properties of acid, calcium and rennet milk gels. By decreasing the pH from 6.0 to 5.2 (acid gels), the calcium equilibrium was significantly affected by temperature (4, 20, 30, 40 oC), and different combinations...... of temperature and pH may result in different final structure properties in dairy products such as cheese. A significant amount of calcium remained in the micelles between pH 4.8 and 4.6, this can contribute to the final strength of acid milk gels, such as in yogurt or in cream cheeses. After the gelation point......, a sudden solubilization of micellar calcium was observed at 50 oC and 60 oC, which revealed an interesting role of calcium during acidification at elevated temperatures. After enrichment of milk with calcium D-lactobionate, the added calcium was distributed between the micellar and serum milk phase at pH 6...

  19. Targeting of CaV3.2 T-type calcium channels in peripheral sensory neurons for the treatment of painful diabetic neuropathy.

    Science.gov (United States)

    Todorovic, Slobodan M; Jevtovic-Todorovic, Vesna

    2014-04-01

    Pain-sensing sensory neurons (nociceptors) of the dorsal root ganglion (DRG) can become sensitized (hyperexcitable) in response to pathological conditions such as diabetes, which in turn may lead to the development of painful peripheral diabetic neuropathy (PDN). Because of insufficient knowledge about the mechanisms for this hypersensitization, current treatment for painful PDN has been limited to somewhat nonspecific systemic drugs having significant side effects or potential for abuse. Recent studies have established that the CaV3.2 isoform of T-channels makes a previously unrecognized contribution to sensitization of pain responses by enhancing excitability of nociceptors in animal models of type 1 and type 2 PDN. Furthermore, it has been reported that the glycosylation inhibitor neuraminidase can inhibit the native and recombinant CaV3.2 T-currents in vitro and completely reverse mechanical and thermal hyperalgesia in diabetic animals with PDN in vivo. Understanding details of posttranslational regulation of nociceptive channel activity via glycosylation may facilitate development of novel therapies for treatment of painful PDN. Pharmacological targeting the specific pathogenic mechanism rather than the channel per se may cause fewer side effects and reduce the potential for drug abuse in patients with diabetes.

  20. Targeting of SUMO substrates to a Cdc48-Ufd1-Npl4 segregase and STUbL pathway in fission yeast

    DEFF Research Database (Denmark)

    Køhler, Julie Bonne; Tammsalu, Triin; Jørgensen, Maria Louise Mønster

    2015-01-01

    In eukaryotes, the conjugation of proteins to the small ubiquitin-like modifier (SUMO) regulates numerous cellular functions. A proportion of SUMO conjugates are targeted for degradation by SUMO-targeted ubiquitin ligases (STUbLs) and it has been proposed that the ubiquitin-selective chaperone Cdc...

  1. Plant Calcium Content: Ready to Remodel

    Directory of Open Access Journals (Sweden)

    Mary Lou Guerinot

    2012-08-01

    Full Text Available By identifying the relationship between calcium location in the plant cell and nutrient bioavailability, the plant characteristics leading to maximal calcium absorption by humans can be identified. Knowledge of plant cellular and molecular targets controlling calcium location in plants is emerging. These insights should allow for better strategies for increasing the nutritional content of foods. In particular, the use of preparation-free elemental imaging technologies such as synchrotron X-ray fluorescence (SXRF microscopy in plant biology may allow researchers to understand the relationship between subcellular location and nutrient bioavailability. These approaches may lead to better strategies for altering the location of calcium within the plant to maximize its absorption from fruits and vegetables. These modified foods could be part of a diet for children and adults identified as at-risk for low calcium intake or absorption with the ultimate goal of decreasing the incidence and severity of inadequate bone mineralization.

  2. Plant Calcium Content: Ready to Remodel

    Science.gov (United States)

    Yang, Jian; Punshon, Tracy; Guerinot, Mary Lou; Hirschi, Kendal D.

    2012-01-01

    By identifying the relationship between calcium location in the plant cell and nutrient bioavailability, the plant characteristics leading to maximal calcium absorption by humans can be identified. Knowledge of plant cellular and molecular targets controlling calcium location in plants is emerging. These insights should allow for better strategies for increasing the nutritional content of foods. In particular, the use of preparation-free elemental imaging technologies such as synchrotron X-ray fluorescence (SXRF) microscopy in plant biology may allow researchers to understand the relationship between subcellular location and nutrient bioavailability. These approaches may lead to better strategies for altering the location of calcium within the plant to maximize its absorption from fruits and vegetables. These modified foods could be part of a diet for children and adults identified as at-risk for low calcium intake or absorption with the ultimate goal of decreasing the incidence and severity of inadequate bone mineralization. PMID:23016135

  3. Substitutions in Calcium Aluminates and Calcium Aluminoferrites.

    Science.gov (United States)

    ALUMINUM COMPOUNDS, *CEMENTS, * CALCIUM COMPOUNDS, * FERRITES , *SCIENTIFIC RESEARCH, INFRARED SPECTROSCOPY, X RAY DIFFRACTION, CHEMICAL COMPOSITION, SUBSTITUTES, CHEMICAL ANALYSIS, ALKALI METAL COMPOUNDS.

  4. Calcium channel blocker overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used to ...

  5. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  6. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  7. Analysis of pH and release of calcium of association between melaleuca alternifolia oil and calcium hydroxide

    Directory of Open Access Journals (Sweden)

    Maiara GIONGO

    2017-03-01

    Full Text Available Abstract Introduction The use of intracanal medications with antimicrobial properties is essential for decontaminating root canals during endodontic treatment. Calcium hydroxide is used for this because of its excellent properties. Melaleuca alternifolia oil has shown medicinal importance by demonstrating antifungal and bactericidal action against proven human pathogens. Objective To evaluate the physical and chemical aspects such as pH and calcium release, of Melaleuca alternifolia oil associated with calcium hydroxide, during different time intervals. Material and method Calcium hydroxide powder was added to vehicles to reach a concentration of 72mg / 0.1mL. Three groups were formed: Group I: Calcium Hydroxide + Distilled Water; Group II: Calcium hydroxide + Propylene Glycol; Group III: Calcium hydroxide + Melaleuca oil. The pH of each group was measured after time intervals of 10 minutes; 24 and 48 hours; 7, 15 and 30 days after tooling by a pH meter. Calcium release was analyzed by atomic absorption spectrometry equipped with a calcium hollow cathode lamp. Data were statistically analyzed by using the Kruskall-Wallis and Dunn test. Result Group II showed high pH, similar to group III that remained uniform at 15 and 30 days. Calcium release that began after 24 hours, was similar in Groups II and III, and showed a peak release in 48 hours. Conclusion The association of Melaleuca oil with calcium hydroxide showed good results in the pH and calcium release analyses, and showed action similar to that of propylene glycol + calcium hydroxide.

  8. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

  9. Calcium-induced calcium release supports recruitment of synaptic vesicles in auditory hair cells.

    Science.gov (United States)

    Castellano-Muñoz, Manuel; Schnee, Michael E; Ricci, Anthony J

    2016-01-01

    Hair cells from auditory and vestibular systems transmit continuous sound and balance information to the central nervous system through the release of synaptic vesicles at ribbon synapses. The high activity experienced by hair cells requires a unique mechanism to sustain recruitment and replenishment of synaptic vesicles for continuous release. Using pre- and postsynaptic electrophysiological recordings, we explored the potential contribution of calcium-induced calcium release (CICR) in modulating the recruitment of vesicles to auditory hair cell ribbon synapses. Pharmacological manipulation of CICR with agents targeting endoplasmic reticulum calcium stores reduced both spontaneous postsynaptic multiunit activity and the frequency of excitatory postsynaptic currents (EPSCs). Pharmacological treatments had no effect on hair cell resting potential or activation curves for calcium and potassium channels. However, these drugs exerted a reduction in vesicle release measured by dual-sine capacitance methods. In addition, calcium substitution by barium reduced release efficacy by delaying release onset and diminishing vesicle recruitment. Together these results demonstrate a role for calcium stores in hair cell ribbon synaptic transmission and suggest a novel contribution of CICR in hair cell vesicle recruitment. We hypothesize that calcium entry via calcium channels is tightly regulated to control timing of vesicle fusion at the synapse, whereas CICR is used to maintain a tonic calcium signal to modulate vesicle trafficking. Copyright © 2016 the American Physiological Society.

  10. The Function of the Mitochondrial Calcium Uniporter in Neurodegenerative Disorders

    Directory of Open Access Journals (Sweden)

    Yajin Liao

    2017-02-01

    Full Text Available The mitochondrial calcium uniporter (MCU—a calcium uniporter on the inner membrane of mitochondria—controls the mitochondrial calcium uptake in normal and abnormal situations. Mitochondrial calcium is essential for the production of adenosine triphosphate (ATP; however, excessive calcium will induce mitochondrial dysfunction. Calcium homeostasis disruption and mitochondrial dysfunction is observed in many neurodegenerative disorders. However, the role and regulatory mechanism of the MCU in the development of these diseases are obscure. In this review, we summarize the role of the MCU in controlling oxidative stress-elevated mitochondrial calcium and its function in neurodegenerative disorders. Inhibition of the MCU signaling pathway might be a new target for the treatment of neurodegenerative disorders.

  11. Transgenic plants with increased calcium stores

    Science.gov (United States)

    Wyatt, Sarah (Inventor); Tsou, Pei-Lan (Inventor); Robertson, Dominique (Inventor); Boss, Wendy (Inventor)

    2004-01-01

    The present invention provides transgenic plants over-expressing a transgene encoding a calcium-binding protein or peptide (CaBP). Preferably, the CaBP is a calcium storage protein and over-expression thereof does not have undue adverse effects on calcium homeostasis or biochemical pathways that are regulated by calcium. In preferred embodiments, the CaBP is calreticulin (CRT) or calsequestrin. In more preferred embodiments, the CaBP is the C-domain of CRT, a fragment of the C-domain, or multimers of the foregoing. In other preferred embodiments, the CaBP is localized to the endoplasmic reticulum by operatively associating the transgene encoding the CaBP with an endoplasmic reticulum localization peptide. Alternatively, the CaBP is targeted to any other sub-cellular compartment that permits the calcium to be stored in a form that is biologically available to the plant. Also provided are methods of producing plants with desirable phenotypic traits by transformation of the plant with a transgene encoding a CaBP. Such phenotypic traits include increased calcium storage, enhanced resistance to calcium-limiting conditions, enhanced growth and viability, increased disease and stress resistance, enhanced flower and fruit production, reduced senescence, and a decreased need for fertilizer production. Further provided are plants with enhanced nutritional value as human food or animal feed.

  12. Paclitaxel Induces Apoptosis in Breast Cancer Cells through Different Calcium—Regulating Mechanisms Depending on External Calcium Conditions

    Directory of Open Access Journals (Sweden)

    Zhi Pan

    2014-02-01

    Full Text Available Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and/or was necessary for paclitaxel-induced apoptosis. Our results demonstrated that paclitaxel induced extracellular calcium influx. This mobilization of extracellular calcium contributed to subsequent cytosolic calcium elevation differently, depending on dosage. Under normal extracellular calcium conditions, high dose paclitaxel induced apoptosis-promoting calcium influx, which did not occur in calcium-free conditions. In the absence of extracellular calcium an “Enhanced Calcium Efflux” mechanism in which high dose paclitaxel stimulated calcium efflux immediately, leading to dramatic cytosolic calcium decrease, was observed. In the absence of extracellular calcium, high dose paclitaxel’s stimulatory effects on capacitative calcium entry and apoptosis could not be completely restored. Thus, normal extracellular calcium concentrations are critical for high dose paclitaxel-induced apoptosis. In contrast, low dose paclitaxel mirrored controls, indicating that it occurs independent of extracellular calcium. Thus, extracellular calcium conditions only affect efficacy of high dose paclitaxel-induced apoptosis.

  13. Paclitaxel Induces Apoptosis in Breast Cancer Cells through Different Calcium—Regulating Mechanisms Depending on External Calcium Conditions

    Science.gov (United States)

    Pan, Zhi; Avila, Andrew; Gollahon, Lauren

    2014-01-01

    Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and/or was necessary for paclitaxel-induced apoptosis. Our results demonstrated that paclitaxel induced extracellular calcium influx. This mobilization of extracellular calcium contributed to subsequent cytosolic calcium elevation differently, depending on dosage. Under normal extracellular calcium conditions, high dose paclitaxel induced apoptosis-promoting calcium influx, which did not occur in calcium-free conditions. In the absence of extracellular calcium an “Enhanced Calcium Efflux” mechanism in which high dose paclitaxel stimulated calcium efflux immediately, leading to dramatic cytosolic calcium decrease, was observed. In the absence of extracellular calcium, high dose paclitaxel’s stimulatory effects on capacitative calcium entry and apoptosis could not be completely restored. Thus, normal extracellular calcium concentrations are critical for high dose paclitaxel-induced apoptosis. In contrast, low dose paclitaxel mirrored controls, indicating that it occurs independent of extracellular calcium. Thus, extracellular calcium conditions only affect efficacy of high dose paclitaxel-induced apoptosis. PMID:24549172

  14. Study of the break reaction of Be{sup 11} on Ti{sup 48} target; the towing mode: a spectroscopic tool for the study of nuclei; Etude de la reaction de cassure du {sup 11}Be sur cible de {sup 48}Ti; le towing mode, un outil spectroscopique pour l'etude des noyaux

    Energy Technology Data Exchange (ETDEWEB)

    Lima, V

    2004-10-01

    In a towing mode reaction the projectile picks up a nucleon from the target and then breaks up by emitting one nucleon. The velocity of the emitted nucleon is boosted by the projectile velocity, leading to the emission of the nucleon in a narrow cone around the direction of the scattered projectile. This work is dedicated to the towing mode in halo nuclei such as Be{sup 11}. The experiment was performed at Ganil facility by bombarding a Ti{sup 48} target with a 41 MeV per nucleon Be{sup 11} beam, the reaction studied is: Ti{sup 48}(Be{sup 11}, Be{sup 10} + n + {gamma}). The first chapter reviews the various nuclear processes that take place when 2 nuclei collide with a particular attention for the towing mode. The second chapter is dedicated to solving the time dependant Schroedinger equation (TDSE) in order to assess the impact of various parameters such as incident energy, target charge or the linking energy of the nucleon, on the towing mode reaction. The third chapter deals with the experimental equipment and set-up including detectors and the data acquisition system. Computerized simulations have been performed in order to assess the efficiency of the detecting system, they are presented in the fourth chapter. A comparison between experimental data and the results from TDSE solving, concerning the energy spectra of the emitted particles, has enabled the author to deduce the spectroscopic factors for the different contributions of the fundamental state of Be{sup 11}, they are presented in the last chapter. The cross-sections of the towing mode are of the magnitude of several tens of milli-barns in the case of weakly bound nuclei like Be{sup 11} which make it an efficient tool to study intern structure of nuclei. (A.C.)

  15. Nuclear Calcium Buffering Capacity Shapes Neuronal Architecture*

    Science.gov (United States)

    Mauceri, Daniela; Hagenston, Anna M.; Schramm, Kathrin; Weiss, Ursula; Bading, Hilmar

    2015-01-01

    Calcium-binding proteins (CaBPs) such as parvalbumin are part of the cellular calcium buffering system that determines intracellular calcium diffusion and influences the spatiotemporal dynamics of calcium signals. In neurons, CaBPs are primarily localized to the cytosol and function, for example, in nerve terminals in short-term synaptic plasticity. However, CaBPs are also expressed in the cell nucleus, suggesting that they modulate nuclear calcium signals, which are key regulators of neuronal gene expression. Here we show that the calcium buffering capacity of the cell nucleus in mouse hippocampal neurons regulates neuronal architecture by modulating the expression levels of VEGFD and the complement factor C1q-c, two nuclear calcium-regulated genes that control dendrite geometry and spine density, respectively. Increasing the levels of nuclear calcium buffers by means of expression of a nuclearly targeted form of parvalbumin fused to mCherry (PV.NLS-mC) led to a reduction in VEGFD expression and, as a result, to a decrease in total dendritic length and complexity. In contrast, mRNA levels of the synapse pruning factor C1q-c were increased in neurons expressing PV.NLS-mC, causing a reduction in the density and size of dendritic spines. Our results establish a close link between nuclear calcium buffering capacity and the transcription of genes that determine neuronal structure. They suggest that the development of cognitive deficits observed in neurological conditions associated with CaBP deregulation may reflect the loss of necessary structural features of dendrites and spines. PMID:26231212

  16. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  17. Regulation of calcium homeostasis in activated human neutrophils ...

    African Journals Online (AJOL)

    Objectives. The objectives of the current study were to: (i) present an integrated model for the restoration of calcium homeostasis in activated human neutrophils based on current knowledge and recent research; and (ii) identify potential targets for the modulation of calcium fluxes in activated neutrophils based on this model ...

  18. Calcium acetate or calcium carbonate for hyperphosphatemia of hemodialysis patients: a meta-analysis.

    Science.gov (United States)

    Wang, Yong; Xie, Guoqiang; Huang, Yuanhang; Zhang, Han; Yang, Bo; Mao, Zhiguo

    2015-01-01

    High levels of serum phosphorus both at baseline and during follow-up are associated with increased mortality in dialysis patients, and administration of phosphate binders was independently associated with improved survival among hemodialysis population. Calcium-based phosphate binders are the most commonly used phosphate binders in developing countries for their relatively low costs. To compare the efficacy and safety between calcium carbonate and calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients. PubMed, EMBASE, Cochrane Library, Google scholar and Chinese databases (Wanfang, Weipu, National Knowledge Infrastructure of China) were searched for relevant studies published before March 2014. Reference lists of nephrology textbooks and review articles were checked. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of calcium acetate and calcium carbonate in adult patients with MHD was performed using Review Manager 5.0. A total of ten studies (625 participants) were included in this meta-analysis. There was insufficient data in all-cause mortality and cardiovascular events for meta-analysis. Compared with calcium carbonate group, the serum phosphorus was significantly lower in calcium acetate group after4 weeks' administration (MD -0.15 mmol/L, 95% CI -0.28 to -0.01) and after 8 weeks' administration (MD -0.25 mmol/L, 95% CI -0.40 to -0.11). There was no difference in serum calcium levels or the incidence of hypercalcemia between two groups at 4 weeks and 8 weeks. No statistical difference was found in parathyroid hormone (PTH) levels or serum calcium by phosphorus (Ca x P) product. There was significantly higher risk of intolerance with calcium acetate treatment (RR 3.46, 95% CI 1.48 to 8.26). For hyperphosphatemia treatment, calcium acetate showed better efficacy and with a higher incidence of intolerance compared with calcium carbonate. There are insufficient data to

  19. The microRNA mir-71 inhibits calcium signaling by targeting the TIR-1/Sarm1 adaptor protein to control stochastic L/R neuronal asymmetry in C. elegans.

    Directory of Open Access Journals (Sweden)

    Yi-Wen Hsieh

    Full Text Available The Caenorhabditis elegans left and right AWC olfactory neurons communicate to establish stochastic asymmetric identities, AWC(ON and AWC(OFF, by inhibiting a calcium-mediated signaling pathway in the future AWC(ON cell. NSY-4/claudin-like protein and NSY-5/innexin gap junction protein are the two parallel signals that antagonize the calcium signaling pathway to induce the AWC(ON fate. However, it is not known how the calcium signaling pathway is downregulated by nsy-4 and nsy-5 in the AWC(ON cell. Here we identify a microRNA, mir-71, that represses the TIR-1/Sarm1 adaptor protein in the calcium signaling pathway to promote the AWC(ON identity. Similar to tir-1 loss-of-function mutants, overexpression of mir-71 generates two AWC(ON neurons. tir-1 expression is downregulated through its 3' UTR in AWC(ON, in which mir-71 is expressed at a higher level than in AWC(OFF. In addition, mir-71 is sufficient to inhibit tir-1 expression in AWC through the mir-71 complementary site in the tir-1 3' UTR. Our genetic studies suggest that mir-71 acts downstream of nsy-4 and nsy-5 to promote the AWC(ON identity in a cell autonomous manner. Furthermore, the stability of mature mir-71 is dependent on nsy-4 and nsy-5. Together, these results provide insight into the mechanism by which nsy-4 and nsy-5 inhibit calcium signaling to establish stochastic asymmetric AWC differentiation.

  20. 76 FR 71459 - Prohexadione Calcium; Pesticide Tolerances

    Science.gov (United States)

    2011-11-18

    ... requested that 40 CFR 180.547 be amended by establishing tolerances for residues of the plant growth... subgroups of consumers, including infants and children. Prohexadione calcium is not acutely toxic by the..., and kidneys were the target organ for toxicity in the dogs. Following repeated dermal exposures for 28...

  1. Phase transitions in biogenic amorphous calcium carbonate

    Science.gov (United States)

    Gong, Yutao

    Geological calcium carbonate exists in both crystalline phases and amorphous phases. Compared with crystalline calcium carbonate, such as calcite, aragonite and vaterite, the amorphous calcium carbonate (ACC) is unstable. Unlike geological calcium carbonate crystals, crystalline sea urchin spicules (99.9 wt % calcium carbonate and 0.1 wt % proteins) do not present facets. To explain this property, crystal formation via amorphous precursors was proposed in theory. And previous research reported experimental evidence of ACC on the surface of forming sea urchin spicules. By using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), we studied cross-sections of fresh sea urchin spicules at different stages (36h, 48h and 72h after fertilization) and observed the transition sequence of three mineral phases: hydrated ACC → dehydrated ACC → biogenic calcite. In addition, we unexpectedly found hydrated ACC nanoparticles that are surrounded by biogenic calcite. This observation indicates the dehydration from hydrated ACC to dehydrated ACC is inhibited, resulting in stabilization of hydrated ACC nanoparticles. We thought that the dehydration was inhibited by protein matrix components occluded within the biomineral, and we designed an in vitro assay to test the hypothesis. By utilizing XANES-PEEM, we found that SM50, the most abundant occluded matrix protein in sea urchin spicules, has the function to stabilize hydrated ACC in vitro.

  2. Quantification of Dialytic Removal and Extracellular Calcium Mass Balance during a Weekly Cycle of Hemodialysis.

    Directory of Open Access Journals (Sweden)

    Jacek Waniewski

    Full Text Available The removal of calcium during hemodialysis with low calcium concentration in dialysis fluid is generally slow, and the net absorption of calcium from dialysis fluid is often reported. The details of the calcium transport process during dialysis and calcium mass balance in the extracellular fluid, however, have not been fully studied.Weekly cycle of three dialysis sessions with interdialytic breaks of 2-2-3 days was monitored in 25 stable patients on maintenance hemodialysis with calcium concentration in dialysis fluid of 1.35 mmol/L. Total and ionic calcium were frequently measured in blood and dialysate. The volume of fluid compartments was measured by bioimpedance.Weekly dialytic removal of 12.79 ± 8.71 mmol calcium was found in 17 patients, whereas 9.48 ± 8.07 mmol calcium was absorbed per week from dialysis fluid in 8 patients. Ionic calcium was generally absorbed from dialysis fluid, whereas complexed calcium (the difference of total and ionic calcium in dialysis fluid was removed from the body. The concentration of total calcium in plasma increased slightly during dialysis. The mass of total and ionic calcium in extracellular fluid decreased during dialysis in patients with the dialytic removal of calcium from the body and did not change in patients with the absorption of calcium from dialysis fluid.We conclude that about one third of patients on dialysis with calcium 1.35 mmol/L in dialysis fluid may absorb calcium from dialysis fluid and therefore individual prescriptions of calcium concentration in dialysis fluid should be considered for such patients.

  3. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

  4. The relation of carotid calcium volume with carotid artery stenosis in symptomatic patients

    NARCIS (Netherlands)

    Marquering, H. A.; Majoie, C. B. L. M.; Smagge, L.; Kurvers, A. G.; Gratama van Andel, H. A.; van den Berg, R.; Nederkoorn, P. J.

    2011-01-01

    Recent research showed a strong correlation of calcium volume scores with degree of stenosis, suggesting that calcium volume could be used in the diagnosis of carotid artery stenosis. We investigated the accuracy of the use of calcium volume scores to diagnose carotid artery stenosis in our target

  5. Calcium and bones

    Science.gov (United States)

    ... eat in their diet. Vitamin D is the hormone that helps the gut absorb more calcium. Many older adults have common risks that make bone health worse. Calcium intake in the diet (milk, cheese, yogurt) is low. Vitamin D levels are ...

  6. Extracellular Calcium and Magnesium

    African Journals Online (AJOL)

    ABSTRACT. The cause of preeclampsia remains unknown and calcium and magnesium supplement are being suggested as means of prevention. The objective of this study was to assess magnesium and calcium in the plasma and cerebrospinal fluid of Nigerian women with preedamp sia and eclampsia. Setting was ...

  7. Paclitaxel Induces Apoptosis in Breast Cancer Cells through Different Calcium—Regulating Mechanisms Depending on External Calcium Conditions

    OpenAIRE

    Zhi Pan; Andrew Avila; Lauren Gollahon

    2014-01-01

    Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and...

  8. Pseudogout and Calcium Pyrophosphate Disease

    Directory of Open Access Journals (Sweden)

    Andrew Williamson

    2017-01-01

    Full Text Available History of present illness: A 53-year-old male presented with worsening right knee pain and swelling over the past 48 hours. He denied recent trauma to the knee, history of IV drug use, and recent illness. He had no history of diabetes, immunodeficiency, chronic steroids, rheumatologic disease, or knee replacement. He described the pain as sharp, non-radiating, and worse with movement. He was unable to walk due to pain. Significant findings: Radiographs of the knee showed multiple radio-dense lines paralleling the articular surface (see red arrows consistent with calcium pyrophosphate crystal deposition within the joint often seen in calcium pyrophosphate disease (CPPD also known as pseudogout. Discussion: Patients commonly present to the emergency department with non-traumatic joint pain. Arthrocentesis is an important diagnostic tool to evaluate for septic arthritis, gout, or pseudogout. Arthrocentesis can demonstrate crystals or abnormal cell count, gram stain, and culture.[1] In the evaluation of joint pain, plain films are usually obtained to evaluate for fracture, dislocation, effusion, or secondary signs of infection. In this case the classic x-ray supported the diagnosis of CPPD.2 The patient was found to have positively birefringent rhomboid shaped crystals consistent with pseudogout on arthrocentesis. Gram stain and culture were both negative. The patient was discharged with NSAIDs and had significant improvement in symptoms upon follow up with primary care physician in 3 days.

  9. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free

  10. Imidazopyridazine inhibitors of Plasmodium falciparum calcium dependent protein kinase 1 also target cGMP-dependent protein kinase and heat shock protein 90 to kill the parasite at different stages of intracellular development.

    OpenAIRE

    Green, JL; Moon, RW; Whalley, D; Bowyer, PW; Wallace, C.; Rochani, A; Nageshan, RK; Howell, SA; Grainger, M.; Jones, HM; Ansell, KH; Chapman, TM; Taylor, DL; Osborne, SA; Baker, DA

    2015-01-01

    : Imidazopyridazine compounds are potent, ATP-competitive inhibitors of calcium-dependent protein kinase 1 (CDPK1) and of Plasmodium falciparum parasite growth in vitro. Here, we show that these compounds can be divided into two classes depending on the nature of the aromatic linker between the core and the R2 substituent group. Class 1 compounds have a pyrimidine linker and inhibit parasite growth at late schizogony, whereas class 2 compounds have a nonpyrimidine linker and inhibit growth in...

  11. Effects of Calcium Ion, Calpains, and Calcium Channel Blockers on Retinitis Pigmentosa

    Directory of Open Access Journals (Sweden)

    Mitsuru Nakazawa

    2011-01-01

    Full Text Available Recent advances in molecular genetic studies have revealed many of the causative genes of retinitis pigmentosa (RP. These achievements have provided clues to the mechanisms of photoreceptor degeneration in RP. Apoptosis is known to be a final common pathway in RP and, therefore, a possible therapeutic target for photoreceptor rescue. However, apoptosis is not a single molecular cascade, but consists of many different reactions such as caspase-dependent and caspase-independent pathways commonly leading to DNA fractionation and cell death. The intracellular concentration of calcium ions is also known to increase in apoptosis. These findings suggest that calpains, one of the calcium-dependent proteinases, play some roles in the process of photoreceptor apoptosis and that calcium channel antagonists may potentially inhibit photoreceptor apoptosis. Herein, the effects of calpains and calcium channel antagonists on photoreceptor degeneration are reviewed.

  12. Calcium sensing in exocytosis

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

    2012-01-01

    Neurotransmitters, neuropeptides and hormones are released through regulated exocytosis of synaptic vesicles and large dense core vesicles. This complex and highly regulated process is orchestrated by SNAREs and their associated proteins. The triggering signal for regulated exocytosis is usually...... an increase in intracellular calcium levels. Besides the triggering role, calcium signaling modulates the precise amount and kinetics of vesicle release. Thus, it is a central question to understand the molecular machineries responsible for calcium sensing in exocytosis. Here we provide an overview of our...

  13. Effects of somatostatin on intestinal calcium transport in the rat.

    Science.gov (United States)

    Favus, M J; Berelowitz, M; Coe, F L

    1981-09-01

    The addition of somatostatin (SRIF) to rat descending colon in vitro increased the calcium secretory flux from serosa to mucosa (Js leads to m) and reduced tissue short-circuit current (Isc) but did not alter the absorptive flux from mucosa to serosa (Js leads to m). Js leads to m increased by 37% at 10(-9) M SRIF and by 48% at 10(-6) M. The response to SRIF was not altered by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and SRIF did not interfere with stimulation of calcium Jm leads to s by 1,25(OH)2D3. Removal of sodium from the buffer abolished the stimulation of Js leads to m by SRIF without reducing basal Js leads to m. Secretory fluxes of mannitol and calcium were strongly correlated in the presence and absence of SRIF, suggesting that SRIF stimulates a paracellular transepithelial pathway for calcium. In the duodenum, SRIF altered neither calcium Js leads to m nor Isc. In the ileum, calcium Js leads to m increased and Isc decreased, as in the colon, but only by 28 and 12%, respectively. The maximal change in calcium Js leads to m caused by SRIF in these three intestinal segments was negatively correlated with the tissue concentration of immunoreactive SRIF. These results suggest that intestinal calcium secretion could, in part, be regulated by intestinal SRIF.

  14. Bone repair in calcium-deficient rats: comparison of xylitol+calcium carbonate with calcium carbonate, calcium lactate and calcium citrate on the repletion of calcium.

    Science.gov (United States)

    Hämäläinen, M M

    1994-06-01

    The potential value of xylitol in calcium therapy was evaluated by comparing the effect of dietary xylitol (50 g/kg diet) + calcium carbonate with the effects of calcium carbonate, calcium lactate and calcium citrate on bone repair of young male rats after the rats consumed for 3 wk a calcium-deficient diet (0.2 g Ca/kg diet). After this calcium-depletion period, the rats were fed for 2 wk one of four diets, each containing 5 g Ca/kg diet as one of the four dietary calcium sources. The diet of the control animals was supplemented with CaCO3 (5 g Ca/kg diet) throughout the study. The Ca-deficient rats showed low bone mass, low serum calcium and high serum 1,25-dihydroxycholecalciferol, parathyroid hormone (1-34 fraction) and osteocalcin concentrations. They also excreted magnesium, phosphate and hydroxyproline in the urine in high concentrations, and had high bone alkaline phosphatase and tartrate-resistant acid phosphatase activities. Most of these changes were reversed by the administered of the calcium salts. The highest recoveries of femoral dry weight, calcium, magnesium and phosphate were observed in the groups receiving xylitol+CaCO3 and calcium lactate. Calcium lactate and calcium citrate caused low serum phosphate concentration compared with rats receiving CaCO3 and with the age-matched Ca-replete controls. Xylitol-treated rats excreted more calcium and magnesium in urine than did the other rats, probably due to increased absorption of these minerals from the gut. These results suggest that dietary xylitol improves the bioavailability of calcium salts.

  15. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears ...

  16. Calcium and Your Child

    Science.gov (United States)

    ... Milk Allergy Figuring Out Food Labels What's a Vegetarian? Osteoporosis Minerals Your Bones Mineral Chart Vitamin D ... Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium Bones, Muscles, and ...

  17. Stoichiometry of Calcium Medicines

    Science.gov (United States)

    Pinto, Gabriel

    2005-01-01

    The topic of calcium supplement and its effects on human lives is presented in the way of questions to the students. It enables the students to realize the relevance of chemistry outside the classroom surrounding.

  18. Magnesium, calcium and cancer

    National Research Council Canada - National Science Library

    Anghileri, Leopoldo J

    2009-01-01

    Magnesium ion (Mg(2+)) and calcium ion (Ca(2+)) control a diverse and important range of cellular processes, such as gene transcription, cell proliferation, neoplastic transformation, immune response and therapeutic treatment...

  19. Optimisation and validation of a high throughput screening compatible assay to identify inhibitors of the plasma membrane calcium ATPase pump--a novel therapeutic target for contraception and malaria.

    Science.gov (United States)

    Mohamed, Tamer M A; Zakeri, Simon A; Baudoin, Florence; Wolf, Markus; Oceandy, Delvac; Cartwright, Elizabeth J; Gul, Sheraz; Neyses, Ludwig

    2013-01-01

    ATPases, which constitute a major category of ion transporters in the human body, have a variety of significant biological and pathological roles. However, the lack of high throughput assays for ATPases has significantly limited drug discovery in this area. We have recently found that the genetic deletion of the ATP dependent calcium pump PMCA4 (plasma membrane calcium/calmodulin dependent ATPase, isoform 4) results in infertility in male mice due to a selective defect in sperm motility. In addition, recent discoveries in humans have indicated that a single nucleotide polymorphism (SNP) in the PMCA4 gene determines the susceptibility towards malaria plasmodium infection. Therefore, there is an urgent need to develop specific PMCA4 inhibitors. In the current study, we aim to optimise and validate a high throughput screening compatible assay using recombinantly expressed PMCA4 and the HTRF® Transcreener® ADP (TR-FRET) assay to screen a drug library. PMCA4 membrane microsomes were prepared from HEK293 cells overexpressing PMCA4. Western blot quantification revealed nearly nine-fold increased expression of PMCA4 compared to LacZ (control virus)-infected cells. Maximal PMCA4 microsomal activity was achieved in the TR-FRET assay with 15ng/μl microsomal concentration, 30-minute pre-incubation with compounds at 37°C, and calcium buffering with 1mM EGTA providing 1μM free-calcium. Finally a dose-response curve for carboxyeosin (a non-specific PMCA inhibitor) under optimised conditions showed significant PMCA4 inhibition. Upon confirmation that the assay was suitable for high-throughput screening, we have screened the ChemBioNet small molecule library (~21,000 compounds) against the PMCA4 assay to identify those that are its apparent inhibitors. This screening yielded 1,494 primary hits. We have optimised the HTRF® Transcreener® ADP assay for high-throughput screening to identify PMCA4 inhibitors. The output of the screening campaign has provided preliminary chemical

  20. Voltage-Gated Calcium Channels in Nociception

    Science.gov (United States)

    Yasuda, Takahiro; Adams, David J.

    Voltage-gated calcium channels (VGCCs) are a large and functionally diverse group of membrane ion channels ubiquitously expressed throughout the central and peripheral nervous systems. VGCCs contribute to various physiological processes and transduce electrical activity into other cellular functions. This chapter provides an overview of biophysical properties of VGCCs, including regulation by auxiliary subunits, and their physiological role in neuronal functions. Subsequently, then we focus on N-type calcium (Cav2.2) channels, in particular their diversity and specific antagonists. We also discuss the role of N-type calcium channels in nociception and pain transmission through primary sensory dorsal root ganglion neurons (nociceptors). It has been shown that these channels are expressed predominantly in nerve terminals of the nociceptors and that they control neurotransmitter release. To date, important roles of N-type calcium channels in pain sensation have been elucidated genetically and pharmacologically, indicating that specific N-type calcium channel antagonists or modulators are particularly useful as therapeutic drugs targeting chronic and neuropathic pain.

  1. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

  2. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  3. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity.

    Directory of Open Access Journals (Sweden)

    L Niels Cornelisse

    Full Text Available Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action potentials (AP are almost never measured due to technical limitations, but they could be crucial for synaptic plasticity. With high-speed, precisely-targeted, two-photon point imaging we measured both calcium rise and decay kinetics in spines and secondary dendrites in neocortical pyramidal neurons. We found that both rise and decay kinetics of changes in calcium-indicator fluorescence are about twice as fast in spines. During AP trains, spine calcium changes follow each AP, but not in dendrites. Apart from the higher surface-to-volume ratio (SVR, we observed that neocortical dendritic spines have a markedly smaller endogenous buffer capacity with respect to their parental dendrites. Calcium influx time course and calcium extrusion rate were both in the same range for spines and dendrites when fitted with a dynamic multi-compartment model that included calcium binding kinetics and diffusion. In a subsequent analysis we used this model to investigate which parameters are critical determinants in spine calcium dynamics. The model confirmed the experimental findings: a higher SVR is not sufficient by itself to explain the faster rise time kinetics in spines, but only when paired with a lower buffer capacity in spines. Simulations at zero calcium-dye conditions show that calmodulin is more efficiently activated in spines, which indicates that spine morphology and buffering conditions in neocortical spines favor synaptic plasticity.

  4. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity.

    Science.gov (United States)

    Cornelisse, L Niels; van Elburg, Ronald A J; Meredith, Rhiannon M; Yuste, Rafael; Mansvelder, Huibert D

    2007-10-24

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action potentials (AP) are almost never measured due to technical limitations, but they could be crucial for synaptic plasticity. With high-speed, precisely-targeted, two-photon point imaging we measured both calcium rise and decay kinetics in spines and secondary dendrites in neocortical pyramidal neurons. We found that both rise and decay kinetics of changes in calcium-indicator fluorescence are about twice as fast in spines. During AP trains, spine calcium changes follow each AP, but not in dendrites. Apart from the higher surface-to-volume ratio (SVR), we observed that neocortical dendritic spines have a markedly smaller endogenous buffer capacity with respect to their parental dendrites. Calcium influx time course and calcium extrusion rate were both in the same range for spines and dendrites when fitted with a dynamic multi-compartment model that included calcium binding kinetics and diffusion. In a subsequent analysis we used this model to investigate which parameters are critical determinants in spine calcium dynamics. The model confirmed the experimental findings: a higher SVR is not sufficient by itself to explain the faster rise time kinetics in spines, but only when paired with a lower buffer capacity in spines. Simulations at zero calcium-dye conditions show that calmodulin is more efficiently activated in spines, which indicates that spine morphology and buffering conditions in neocortical spines favor synaptic plasticity.

  5. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  6. Finite element model to study calcium distribution in oocytes ...

    African Journals Online (AJOL)

    Parvaiz Ahmad Naik

    2015-03-20

    Mar 20, 2015 ... ing species studied to date from plants to humans.4,6 The fer- tilization ... mathematical model of simulation of spontaneous Ca2+ oscil- lations in ..... Membrane potential. А0:05 V. zCa. Valency of calcium. 2. VOocyte. Volume of oocyte cytosol. 5:48 В 10А11 l. F. Faraday's constant. 96487 C=mole. R.

  7. Calcium orthophosphates in dentistry.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2013-06-01

    Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.

  8. Calcium Signalling: Fishing Out Molecules of Mitochondrial Calcium Transport

    OpenAIRE

    Hajnóczky, György; Csordás, György

    2010-01-01

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins — MICU1, NCLX and LETM1 — to the previously unknown molecular mechanism of mitochondrial calcium transport.

  9. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  10. Calcium pathway machinery at fertilization in echinoderms.

    Science.gov (United States)

    Ramos, Isabela; Wessel, Gary M

    2013-01-01

    Calcium signaling in cells directs diverse physiological processes. The calcium waves triggered by fertilization is a highly conserved calcium signaling event essential for egg activation, and has been documented in every egg tested. This activity is one of the few highly conserved events of egg activation through the course of evolution. Echinoderm eggs, as well as many other cell types, have three main intracellular Ca(2+) mobilizing messengers - IP3, cADPR and NAADP. Both cADPR and NAADP were identified as Ca(2+) mobilizing messengers using the sea urchin egg homogenate, and this experimental system, along with the intact urchin and starfish oocyte/egg, continues to be a vital tool for investigating the mechanism of action of calcium signals. While many of the major regulatory steps of the IP3 pathway are well resolved, both cADPR and NAADP remain understudied in terms of our understanding of the fundamental process of egg activation at fertilization. Recently, NAADP has been shown to trigger Ca(2+) release from acidic vesicles, separately from the ER, and a new class of calcium channels, the two-pore channels (TPCs), was identified as the likely targets for this messenger. Moreover, it was found that both cADPR and NAADP can be synthesized by the same family of enzymes, the ADP-rybosyl cyclases (ARCs). In this context of increasing amount of information, the potential coupling and functional roles of different messengers, intracellular stores and channels in the formation of the fertilization calcium wave in echinoderms will be critically evaluated. Copyright © 2012. Published by Elsevier India Pvt Ltd.

  11. Discovery and Development of Calcium Channel Blockers

    Directory of Open Access Journals (Sweden)

    Théophile Godfraind

    2017-05-01

    Full Text Available In the mid 1960s, experimental work on molecules under screening as coronary dilators allowed the discovery of the mechanism of calcium entry blockade by drugs later named calcium channel blockers. This paper summarizes scientific research on these small molecules interacting directly with L-type voltage-operated calcium channels. It also reports on experimental approaches translated into understanding of their therapeutic actions. The importance of calcium in muscle contraction was discovered by Sidney Ringer who reported this fact in 1883. Interest in the intracellular role of calcium arose 60 years later out of Kamada (Japan and Heibrunn (USA experiments in the early 1940s. Studies on pharmacology of calcium function were initiated in the mid 1960s and their therapeutic applications globally occurred in the the 1980s. The first part of this report deals with basic pharmacology in the cardiovascular system particularly in isolated arteries. In the section entitled from calcium antagonists to calcium channel blockers, it is recalled that drugs of a series of diphenylpiperazines screened in vivo on coronary bed precontracted by angiotensin were initially named calcium antagonists on the basis of their effect in depolarized arteries contracted by calcium. Studies on arteries contracted by catecholamines showed that the vasorelaxation resulted from blockade of calcium entry. Radiochemical and electrophysiological studies performed with dihydropyridines allowed their cellular targets to be identified with L-type voltage-operated calcium channels. The modulated receptor theory helped the understanding of their variation in affinity dependent on arterial cell membrane potential and promoted the terminology calcium channel blocker (CCB of which the various chemical families are introduced in the paper. In the section entitled tissue selectivity of CCBs, it is shown that characteristics of the drug, properties of the tissue, and of the stimuli are

  12. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Email Share Dialog × Print Children's Bone Health and Calcium: Condition Information What is bone health and how ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  13. Stable prenucleation calcium carbonate clusters

    OpenAIRE

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-01-01

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate...

  14. Assay for calcium channels

    Energy Technology Data Exchange (ETDEWEB)

    Glossmann, H.; Ferry, D.R.

    1985-01-01

    This chapter focuses on biochemical assays for Ca/sup 2 +/-selective channels in electrically excitable membranes which are blocked in electrophysiological and pharmacological experiments by verapamil, 1,4-dihydropyridines, diltiazen (and various other drugs), as well as inorganic di- or trivalent cations. The strategy employed is to use radiolabeled 1,4-dihydropyridine derivatives which block calcium channels with ED/sub 50/ values in the nanomolar range. Although tritiated d-cis-diltiazem and verapamil can be used to label calcium channels, the 1,4-dihydropyridines offer numerous advantages. The various sections cover tissue specificity of channel labeling, the complex interactions of divalent cations with the (/sup 3/H)nimodipine-labeled calcium channels, and the allosteric regulation of (/sup 3/H)nimodipine binding by the optically pure enantiomers of phenylalkylamine and benzothiazepine calcium channel blockers. A comparison of the properties of different tritiated 1,4-dihydropyridine radioligands and the iodinated channel probe (/sup 125/I)iodipine is given.

  15. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500...

  16. The Plasma Membrane Calcium Pump

    Science.gov (United States)

    Rasmussen, H.

    1983-01-01

    Three aspect of cellular calcium metabolism in animal cells was discussed including the importance of the plasma membrane in calcium homeostasis, experiments dealing with the actual mechanism of the calcium pump, and the function of the pump in relationship to the mitochondria and to the function of calmodulin in the intact cell.

  17. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...

  18. Impregnating Coal With Calcium Carbonate

    Science.gov (United States)

    Sharma, Pramod K.; Voecks, Gerald E.; Gavalas, George R.

    1991-01-01

    Relatively inexpensive process proposed for impregnating coal with calcium carbonate to increase rates of gasification and combustion of coal and to reduce emission of sulfur by trapping sulfur in calcium sulfide. Process involves aqueous-phase reactions between carbon dioxide (contained within pore network of coal) and calcium acetate. Coal impregnated with CO2 by exposing it to CO2 at high pressure.

  19. Concurrent imaging of synaptic vesicle recycling and calcium dynamics.

    Directory of Open Access Journals (Sweden)

    Haiyan eLi

    2011-11-01

    Full Text Available Synaptic transmission involves the calcium-dependent release of neurotransmitter from synaptic vesicles. Genetically encoded optical probes emitting different wavelengths of fluorescent light in response to neuronal activity offer a powerful approach to understand the spatial and temporal relationship of calcium dynamics to the release of neurotransmitter in defined neuronal populations. To simultaneously image synaptic vesicle recycling and changes in cytosolic calcium, we developed a red-shifted reporter of vesicle recycling based on a vesicular glutamate transporter, VGLUT1-mOrange2 (VGLUT1-mOr2, and a presynaptically-localized green calcium indicator, synaptophysin-GCaMP3 (SyGCaMP3 with a large dynamic range. The fluorescence of VGLUT1-mOr2 is quenched by the low pH of synaptic vesicles. Exocytosis upon electrical stimulation exposes the luminal mOr2 to the neutral extracellular pH and relieves fluorescence quenching. Re-acidification of the vesicle upon endocytosis again reduces fluorescence intensity. Changes in fluorescence intensity thus monitor synaptic vesicle exo- and endocytosis, as demonstrated previously for the green VGLUT1-pHluorin. To monitor changes in calcium, we fused the synaptic vesicle protein synaptophysin to the recently improved calcium indicator GCaMP3. SyGCaMP3 is targeted to presynaptic varicosities, and exhibits changes in fluorescence in response to electrical stimulation consistent with changes in calcium concentration. Using real-time imaging of both reporters expressed in the same synapses, we determine the time course of changes in VGLUT1 recycling in relation to changes in presynaptic calcium concentration. Inhibition of P/Q- and N-type calcium channels reduces calcium levels, as well as the rate of synaptic vesicle exocytosis and the fraction of vesicles released.

  20. 48 CFR 48.001 - Definitions.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Definitions. 48.001 Section 48.001 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT... means agency costs of operation, maintenance logistic support, or Government-furnished property...

  1. Calcium signaling in taste cells.

    Science.gov (United States)

    Medler, Kathryn F

    2015-09-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Interaction of H2S with Calcium Permeable Channels and Transporters

    Directory of Open Access Journals (Sweden)

    Weihua Zhang

    2015-01-01

    Full Text Available A growing amount of evidence has suggested that hydrogen sulfide (H2S, as a gasotransmitter, is involved in intensive physiological and pathological processes. More and more research groups have found that H2S mediates diverse cellular biological functions related to regulating intracellular calcium concentration. These groups have demonstrated the reciprocal interaction between H2S and calcium ion channels and transporters, such as L-type calcium channels (LTCC, T-type calcium channels (TTCC, sodium/calcium exchangers (NCX, transient receptor potential (TRP channels, β-adrenergic receptors, and N-methyl-D-aspartate receptors (NMDAR in different cells. However, the understanding of the molecular targets and mechanisms is incomplete. Recently, some research groups demonstrated that H2S modulates the activity of calcium ion channels through protein S-sulfhydration and polysulfide reactions. In this review, we elucidate that H2S controls intracellular calcium homeostasis and the underlying mechanisms.

  3. Expert review on coronary calcium

    Directory of Open Access Journals (Sweden)

    Matthew J Budoff

    2008-04-01

    Full Text Available Matthew J Budoff, Khawar M GulDivision of Cardiology, Saint John’s Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, California, USAAbstract: While there is no doubt that high risk patients (those with >20% ten year risk of future cardiovascular event need more aggressive preventive therapy, a majority of cardiovascular events occur in individuals at intermediate risk (10%–20% ten year risk. Accurate risk assessment may be helpful in decreasing cardiovascular events through more appropriate targeting of preventive measures. It has been suggested that traditional risk assessment may be refined with the selective use of coronary artery calcium (CAC or other methods of subclinical atherosclerosis measurement. Coronary calcification is a marker of atherosclerosis that can be quantified with the use of cardiac CT and it is proportional to the extent and severity of atherosclerotic disease. The published studies demonstrate a high sensitivity of CAC for the presence of coronary artery disease but a lower specificity for obstructive CAD depending on the magnitude of the CAC. Several large clinical trials found clear, incremental predictive value of CAC over the Framingham risk score when used in asymptomatic patients. Based on multiple observational studies, patients with increased plaque burdens (increased CAC are approximately ten times more likely to suffer a cardiac event over the next 3–5 years. Coronary calcium scores have outperformed conventional risk factors, highly sensitive C-reactive protein (CRP and carotid intima media thickness (IMT as a predictor of cardiovascular events. The relevant prognostic information obtained may be useful to initiate or intensify appropriate treatment strategies to slow the progression of atherosclerotic vascular disease. Current data suggests intermediate risk patients may benefit most from further risk stratification with cardiac CT, as CAC testing is

  4. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  5. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P platelet free calcium (intracellular calcium concentration) were also reduced (P metabolism (P metabolism are relatively impervious to dietary calcium in the short term, 2) increased ionized calcium did not normalize low-calcium-induced elevations of BP, and 3) parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  6. Diagnosis of alterations of serum calcium metabolism.

    Science.gov (United States)

    Lumachi, Franco; Cappelletti, Piero; Tozzoli, Renato; Basso, Stafano M M; Luisetto, Giovanni; Camozzi, Valentina

    2012-07-01

    Calcium is essential to homeostasis and functioning of multiple organ systems. Its circulating concentration is maintained within a very tight physiologic range: 2.25 and 2.50 mmol/L. Under physiological conditions, the ionized calcium concentration is regulated by the parathyroid hormone (PTH), and 1,25(OH)(2) vitamin D through interactions on target organs such as kidney, bone and intestine. In mild, moderate, and severe hypercalcemia, laboratory findings are essential in assessing and monitoring disease course and therapy. The main tools are specific standard biochemical tests able to assess calcium balance and renal function, and some specific biochemical tests, such as PTH, 25(OH) vitamin D, and genetic sequencing, used to clarify the cause of hypercalcemia and, subsequently, to determine appropriate therapy. Once hypercalcemia is confirmed by ionized calcium measurement, the intact PTH assay plays a crucial role to differentiate PTH-mediated from non-PTH-mediated hypercalcemia. Mild hypercalcemia is also present in up to 10-20% of patients treated with lithium for bipolar disorders, in 7-8% of those treated with thiazide diuretics, and in patients with prolonged immobilization, while very high (>3.5 mmol/L) serum calcium levels, together with low PTH, and a rapid increase of hypercalcemia, usually suggest a malignancy-associated hypercalcemic syndrome. The measurement of PTH-related protein, a tumor product that mimics certain action of PTH, is useful only in selected cases. The role of biochemical markers of bone turnover for predicting metastatic bone disease, and monitoring bone metabolic changes, and their usefulness as a predictive mean of the likelihood of bone loss or fractures risk is still unclear.

  7. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  8. Calcium and Magnesium Metabolism in Pre-Eclampsia.

    Science.gov (United States)

    Udenze, I C; Arikawe, A P; Azinge, E C; Okusanya, B O; Ebuehi, O A

    2014-01-01

    Preeclampsia is a multisystem disorder associated with high maternal and perinatal mortality and morbidity. The cause of the disorder is largely unknown and its pathogenesis is complex and poorly understood. Calcium and magnesium are divalent ions which may have roles to play in the manifestations of the disease. An understanding of their metabolism in preeclampsia may aid our management of pregnant women who develop the disease. To determine the plasma and urinary concentrations of calcium, magnesium and parathyroid hormone in women with mild, severe preeclampsia and in normal pregnancy. This is was a case control study of fifty women with mild preeclampsia, fifty women with severe preeclampsia and fifty women with normal pregnancy as controls, drawn from The Antenatal Clinic at the Lagos University Teaching Hospital, Lagos, Nigeria. The women were consecutively recruited after signing an informed consent form. Ethical approval was obtained from the medical ethics committee of the hospital. The three groups of women were similar in their socio demographic characteristics. Plasma calcium was low in mild and severe preeclampsia compared to normal pregnancy controls (p=0.021). Urine calcium/creatinine ratio was lower in mild and severe preeclampsia compared to normal pregnancy controls (p= 0.030). Fractional excretion of calcium and levels of parathyroid hormone were similar across all three subgroups of women. Plasma magnesium was higher in mild and severe preeclampsia compared to normal pregnancy controls (p=0.011) and showed a positive correlation with plasma creatinine (r=0.48, p=0.045). Parathyroid hormone levels were similar across the study groups. Preeclampsia is associated with significant changes in calcium and magnesium metabolism. This study noted significant hypocalcaemia in mild and severe preeclampsia with significantly low urine calcium/creatinine levels. Calcium supplementation may have a place in patient's management. Hypermagnesemia was observed in

  9. Glucocorticoids specifically enhance L-type calcium current amplitude and affect calcium channel subunit expression in the mouse hippocampus.

    Science.gov (United States)

    Chameau, Pascal; Qin, Yongjun; Spijker, Sabine; Smit, August Benjamin; Smit, Guus; Joëls, Marian

    2007-01-01

    Previous studies have shown that corticosterone enhances whole cell calcium currents in CA1 pyramidal neurons, through a pathway involving binding of glucocorticoid receptor homodimers to the DNA. We examined whether glucocorticoids show selectivity for L- over N-type of calcium currents. Moreover, we addressed the putative gene targets that eventually lead to the enhanced calcium currents. Electrophysiological recordings were performed in nucleated patches that allow excellent voltage control. Calcium currents in these patches almost exclusively involve N- and L-type channels. We found that L- but not N-type calcium currents were largely enhanced after treatment with a high dose of corticosterone sufficient to activate glucocorticoid receptors. Voltage dependency and kinetic properties of the currents were unaffected by the hormone. Nonstationary noise analysis suggests that the increased current is not caused by a larger unitary conductance, but rather to a doubling of the number of functional channels. Quantitative real-time PCR revealed that transcripts of the Ca(v)1 subunits encoding for the N- or L-type calcium channels are not upregulated in the mouse CA1 area; instead, a strong, direct, and consistent upregulation of the beta4 subunit was observed. This indicates that the corticosteroid-induced increase in number of L-type calcium channels is not caused by a simple transcriptional regulation of the pore-forming subunit of the channels.

  10. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia.

    Science.gov (United States)

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance.

  11. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    OpenAIRE

    Bizzozero, Julien; Scrivener, Karen

    2015-01-01

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate ...

  12. Mixed calcium-magnesium pre-nucleation clusters enrich calcium

    OpenAIRE

    Verch, Andreas; Antonietti, Markus; Cölfen, Helmut

    2012-01-01

    It is demonstrated that magnesium and carbonate ions can form pre-nucleation clusters in analogy to calcium carbonate. If a mixed calcium and magnesium solution is brought in contact with carbonate ions, mixed pre-nucleation clusters form. The equilibrium constants for their formation are reported revealing that over the entire range of possible cation mixing ratios, calcium gets enriched over magnesium in the pre-nucleation clusters. This can explain high magnesium contents in amorphous calc...

  13. Biological Reactions to Calcium Phosphate-coated Calcium Carbonate Particles

    National Research Council Canada - National Science Library

    Tetsunari NISHIKAWA; Kazuya MASUNO; Tomoharu OKAMURA; Kazuya TOMINAGA; Masahiro WATO; Mayu KOKUBU; Koichi IMAI; Shoji TAKEDA; Yoichro TAGUCHI; Masatoshi UEDA; Akio TANAKA

    2010-01-01

    [SYNOPSIS][Objectives]: In order to histopathologically investigate biological reactions to materials used for scaffolds, we examined the cytotoxicity to calcium particles in vitro and bioabsorption in vivo...

  14. Osteoporosis, calcium and physical activity.

    OpenAIRE

    Martin, A. D.; Houston, C S

    1987-01-01

    Sales of calcium supplements have increased dramatically since 1983, as middle-aged women seek to prevent or treat bone loss due to osteoporosis. However, epidemiologic studies have failed to support the hypothesis that larger amounts of calcium are associated with increased bone density or a decreased incidence of fractures. The authors examine the evidence from controlled trials on the effects of calcium supplementation and physical activity on bone loss and find that weight-bearing activit...

  15. Photoluminescent calcium azolium carboxylates with diversified calcium coordination geometry and thermal stability.

    Science.gov (United States)

    Suresh, Paladugu; Babu, Chatla Naga; Sampath, Natarajan; Prabusankar, Ganesan

    2015-04-28

    Despite the popularity and versatility of transition-metal–azolium carboxylate coordination polymers, there are very few examples of group 2 complexes supported by azolium carboxylate ligands in the literature, and there are none featuring luminescent calcium azolium carboxylates. New ionic calcium coordination networks, {[Ca2(L(1))2(H2O)4](Br)4·6H2O}∞ (1), {[(L(3))2Ca(H2O)2]2(Br)2}∞ (3), {[(L(4))2Ca(H2O)2]2(Br)2}∞ (4), and {[(L(5))2Ca3(Na)(H2O)9(Cl)](Br)6·2H2O}∞ (5) along with binuclear {[Ca2(L(2))2(H2O)9](Br)4·4H2O} (2), and trinuclear {[(L(6))2Ca3(H2O)9](Br)6} (6) were isolated from the reaction between the corresponding azolium carboxylates and calcium carbonate in aqueous solution. 1–6 were characterized by FT-IR, NMR, TGA, UV-vis, fluorescence and single crystal X-ray diffraction techniques. Interestingly, the first tetra-cationic binuclear calcium 2 was isolated using L(2)H2Br2 and hexa-cationic trinuclear calcium 6 was isolated using L(6)H3Br3. The 3D coordination polymers 1 and 4 were derived with the help of L(1)H2Br2 and L(4)H2Br2, respectively, through Br···H hydrogen bonding. The 3D MOF 3 with rhomboidal channels was constructed using L(3)H2Br2, where the channel size is about 4.8 × 2.9 nm. 5 was isolated as a rare 1D coordination polymer. The choice of azolium carboxylates in these solids not only changes the topology of the network but also affects the chemistry exhibited by the network. Calcium azolium carboxylate assemblies 1–4 and 6 exhibit interesting solid-state photoluminescence properties, driven by azolium carboxylate ligands. Variation of the bridging chromophore produced significant effects on the fluorescence properties. 1–4 and 6 represent the first examples of luminescent calcium azolium carboxylate complexes. As can be seen in the six metal–organic assemblies presented in this report, a combination of carboxylate groups and steric hindrance affects the topology and physical properties of the resultant solids.

  16. Cardiovascular Effects of Calcium Supplements

    Directory of Open Access Journals (Sweden)

    Ian R. Reid

    2013-07-01

    Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

  17. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

    ...) technology selective laser sintering (SLS). BME has successfully implemented a pilot facility to fabricate calcium phosphate implants using anatomical data coupled with the selective laser sintering process...

  18. 21 CFR 73.1070 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... precipitated calcium carbonate (CaCO3). (2) Color additive mixtures for drug use made with calcium carbonate... precipitated calcium carbonate in the United States Pharmacopeia XX (1980). (c) Uses and restrictions. Calcium... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food...

  19. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium carbonate. 184.1191 Section 184.1191 Food... Specific Substances Affirmed as GRAS § 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation...

  20. Layer-by-layer assembled magnetic prednisolone microcapsules (MPC) for controlled and targeted drug release at rheumatoid arthritic joints

    Energy Technology Data Exchange (ETDEWEB)

    Prabu, Chakkarapani [Department of Pharmaceutical Technology & Centre for Excellence in Nanobio Translational Research, Anna University, Bharathidasan Institute of Technology Campus, Tiruchirappalli, Tamil Nadu (India); Latha, Subbiah, E-mail: lathasuba2010@gmail.com [Department of Pharmaceutical Technology & Centre for Excellence in Nanobio Translational Research, Anna University, Bharathidasan Institute of Technology Campus, Tiruchirappalli, Tamil Nadu (India); Selvamani, Palanisamy [Department of Pharmaceutical Technology & Centre for Excellence in Nanobio Translational Research, Anna University, Bharathidasan Institute of Technology Campus, Tiruchirappalli, Tamil Nadu (India); Ahrentorp, Fredrik; Johansson, Christer [Acreo Swedish ICT AB, Arvid Hedvalls Backe 4, Göteborg (Sweden); Takeda, Ryoji; Takemura, Yasushi [Electrical & Computer Engineering & Faculty of Engineering Division of Intelligent Systems Engineering, Yokohama National University (Japan); Ota, Satoshi [Department of Electrical and Electronic Engineering, Shizuoka University (Japan)

    2017-04-01

    We report here in about the formulation and evaluation of Magnetic Prednisolone Microcapsules (MPC) developed in order to improve the therapeutic efficacy relatively at a low dose than the conventional dosage formulations by means of magnetic drug targeting and thus enhancing bioavailability at the arthritic joints. Prednisolone was loaded to poly (sodium 4-styrenesulfonate) (PSS) doped calcium carbonate microspheres confirmed by the decrease in surface area from 97.48 m{sup 2}/g to 12.05 of m{sup 2}/g by BET analysis. Adsorption with oppositely charged polyelectrolytes incorporated with iron oxide nanoparticles was confirmed through zeta analysis. Removal of calcium carbonate core yielded MPC with particle size of ~3.48 µm, zeta potential of +29.7 mV was evaluated for its magnetic properties. Functional integrity of MPC was confirmed through FT-IR spectrum. Stability studies were performed at 25 °C±65% relative humidity for 60 days showed no considerable changes. Further the encapsulation efficiency of 63%, loading capacity of 18.2% and drug release of 88.3% for 36 h and its kinetics were also reported. The observed results justify the suitability of MPC for possible applications in the magnetic drug targeting for efficient therapy of rheumatoid arthritis. - Highlights: • Development of magnetic prednisolone microcapsules (MPC). • Physicochemical, pharmaceutical and magnetic properties of MPC were characterized. • Multiple layers of alternative polyelectrolytes prolonged prednisolone release time. • MPC is capable for targeted and sustained release rheumatoid arthritis therapy.

  1. Calcium Signaling and Cardiac Arrhythmias.

    Science.gov (United States)

    Landstrom, Andrew P; Dobrev, Dobromir; Wehrens, Xander H T

    2017-06-09

    There has been a significant progress in our understanding of the molecular mechanisms by which calcium (Ca2+) ions mediate various types of cardiac arrhythmias. A growing list of inherited gene defects can cause potentially lethal cardiac arrhythmia syndromes, including catecholaminergic polymorphic ventricular tachycardia, congenital long QT syndrome, and hypertrophic cardiomyopathy. In addition, acquired deficits of multiple Ca2+-handling proteins can contribute to the pathogenesis of arrhythmias in patients with various types of heart disease. In this review article, we will first review the key role of Ca2+ in normal cardiac function-in particular, excitation-contraction coupling and normal electric rhythms. The functional involvement of Ca2+ in distinct arrhythmia mechanisms will be discussed, followed by various inherited arrhythmia syndromes caused by mutations in Ca2+-handling proteins. Finally, we will discuss how changes in the expression of regulation of Ca2+ channels and transporters can cause acquired arrhythmias, and how these mechanisms might be targeted for therapeutic purposes. © 2017 American Heart Association, Inc.

  2. Calcium signalling: fishing out molecules of mitochondrial calcium transport.

    Science.gov (United States)

    Hajnóczky, György; Csordás, György

    2010-10-26

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins - MICU1, NCLX and LETM1 - to the previously unknown molecular mechanism of mitochondrial calcium transport. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Calcium nutrition and extracellular calcium sensing: relevance for the pathogenesis of osteoporosis, cancer and cardiovascular diseases.

    Science.gov (United States)

    Peterlik, Meinrad; Kállay, Enikoe; Cross, Heide S

    2013-01-22

    Through a systematic search in Pubmed for literature, on links between calcium malnutrition and risk of chronic diseases, we found the highest degree of evidence for osteoporosis, colorectal and breast cancer, as well as for hypertension, as the only major cardiovascular risk factor. Low calcium intake apparently has some impact also on cardiovascular events and disease outcome. Calcium malnutrition can causally be related to low activity of the extracellular calcium-sensing receptor (CaSR). This member of the family of 7-TM G-protein coupled receptors allows extracellular Ca2+ to function as a "first messenger" for various intracellular signaling cascades. Evidence demonstrates that Ca2+/CaSR signaling in functional linkage with vitamin D receptor (VDR)-activated pathways (i) promotes osteoblast differentiation and formation of mineralized bone; (ii) targets downstream effectors of the canonical and non-canonical Wnt pathway to inhibit proliferation and induce differentiation of colorectal cancer cells; (iii) evokes Ca2+ influx into breast cancer cells, thereby activating pro-apoptotic intracellular signaling. Furthermore, Ca2+/CaSR signaling opens Ca2+-sensitive K+ conductance channels in vascular endothelial cells, and also participates in IP(3)-dependent regulation of cytoplasmic Ca2+, the key intermediate of cardiomyocyte functions. Consequently, impairment of Ca2+/CaSR signaling may contribute to inadequate bone formation, tumor progression, hypertension, vascular calcification and, probably, cardiovascular disease.

  4. Calcium electroporation in three cell lines; a comparison of bleomycin and calcium, calcium compounds, and pulsing conditions

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille

    2013-01-01

    BACKGROUND: Electroporation with calcium (calcium electroporation) can induce ATP depletion-associated cellular death. In the clinical setting, the cytotoxic drug bleomycin is currently used with electroporation (electrochemotherapy) for palliative treatment of tumors. Calcium electroporation off...

  5. Cosmic ray source abundance of calcium

    CERN Document Server

    Perron, C

    1978-01-01

    Re-examines the results of experiments in which ultra-high purity iron targets were irradiated by protons from the two CERN accelerators (600 MeV and 21 GeV); the spallation products were then chemically separated, and their isotopic composition determined by mass spectrometry. Ratios of cross-sections for calcium production by spallation of iron show that /sup 42/Ca, /sup 43/Ca and /sup 44/Ca have about the same abundance, about 10-15% that of iron, confirming earlier studies. (11 refs).

  6. Hybrid Calcium Phosphate Coatings for Titanium Implants

    Science.gov (United States)

    Kharapudchenko, E.; Ignatov, V.; Ivanov, V.; Tverdokhlebov, S.

    2017-01-01

    Hybrid multilayer coatings were obtained on titanium substrates by the combination of two methods: the micro-arc oxidation in phosphoric acid solution with the addition of calcium compounds to high supersaturated state and RF magnetron sputtering of the target made of synthetic hydroxyapatite. 16 different groups of coatings were formed on titanium substrates and in vitro studies were conducted in accordance with ISO 23317 in the solution simulating body fluid. The studies using SEM, XRD of the coatings of the samples before and after exposure to SBF were performed. The features of morphology, chemical and phase composition of the studied coatings are shown.

  7. Confocal microscope is able to detect calcium metabolic in neuronal infection by toxoplasma gondii

    Science.gov (United States)

    Sensusiati, A. D.; Priya, T. K. S.; Dachlan, Y. P.

    2017-05-01

    Calcium metabolism plays a very important role in neurons infected by Toxoplasma. Detection of change of calcium metabolism of neuron infected by Toxoplasma and Toxoplasma requires the calculation both quantitative and qualitative method. Confocal microscope has the ability to capture the wave of the fluorescent emission of the fluorescent dyes used in the measurement of cell calcium. The purpose of this study was to prove the difference in calcium changes between infected and uninfected neurons using confocal microscopy. Neuronal culture of human-skin-derived neural stem cell were divided into 6 groups, consisting 3 uninfected groups and 3 infected groups. Among the 3 groups were 2 hours, 24 hours and 48 hours. The neuron Toxoplasma gondii ratio was 1:5. Observation of intracellular calcium of neuron and tachyzoite, evidence of necrosis, apoptosis and the expression of Hsp 70 of neuron were examined by confocal microscope. The normality of the data was analysed by Kolmogorov-Smirnov Test, differentiation test was checked by t2 Test, and ANOVAs, for correlation test was done by Pearson Correlation Test. The calcium intensity of cytosolic neuron and T. gondii was significantly different from control groups (p<0.05). There was also significant correlation between calcium intensity with the evidence of necrosis and Hsp70 expression at 2 hours after infection. Apoptosis and necrosis were simultaneously shown with calcium contribution in this study. Confocal microscopy can be used to measure calcium changes in infected and uninfected neurons both in quantitatively and qualitatively.

  8. Individual and family correlates of calcium-rich food intake among parents of early adolescent children.

    Science.gov (United States)

    Reicks, Marla; Ballejos, Miriam Edlefsen; Goodell, L Suzanne; Gunther, Carolyn; Richards, Rickelle; Wong, Siew Sun; Auld, Garry; Boushey, Carol J; Bruhn, Christine; Cluskey, Mary; Misner, Scottie; Olson, Beth; Zaghloul, Sahar

    2011-03-01

    Most adults do not meet calcium intake recommendations. Little is known about how individual and family factors, including parenting practices that influence early adolescents' intake of calcium-rich foods, affect calcium intake of parents. This information could inform the development of effective nutrition education programs. To identify individual and family factors associated with intake of calcium-rich foods among parents of early adolescents (aged 10 to 13 years). A cross-sectional survey was used with 14 scales to assess attitudes/preferences and parenting practices regarding calcium-rich foods and a calcium-specific food frequency questionnaire (2006-2007). A convenience sample of self-reporting non-Hispanic white, Hispanic, and Asian (n=661) parents was recruited in nine states. Parents were the primary meal planner/preparer and completed questionnaires in homes or community settings. Predictors of calcium intake from three food groupings-all food sources, dairy foods, and milk. Multivariate regression analyses identified demographic, attitude/preference, and behavioral factors associated with calcium intake. Most respondents were women (∼90%) and 38% had a college degree. Education was positively associated with calcium intake from all three food groupings, whereas having an Asian spouse compared to a non-Hispanic white spouse was negatively associated with calcium intake only from all food sources and from dairy foods. Expectations for and encouragement of healthy beverage intake for early adolescents were positively associated with calcium intake from dairy foods and milk, respectively. Parental concern regarding adequacy of intake was negatively associated, whereas perception of health benefits from calcium-rich foods was positively associated with calcium intake from all food sources and from dairy foods. Between 20% and 32% of the variance in calcium intake from all food groupings was explained in these models. Individual factors and positive

  9. 48 CFR 48.102 - Policies.

    Science.gov (United States)

    2010-10-01

    ... financial risk). (4) Development cost. (5) Performance and/or reliability impact. (6) Production period... 48.102 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT VALUE ENGINEERING Policies and Procedures 48.102 Policies. (a) As required by Section 36 of the Office...

  10. SAFETY INSTRUCTION NO 48 (IS48)

    CERN Multimedia

    TIS Secretariat

    2001-01-01

    Please note that the Safety Instruction no 48 (IS48) entitled 'FIRE PREVENTION FOR CABLES, CABLE TRAYS AND CONDUITS' is available on the web at the following url: Fire Prevention Paper copies can also be obtained from the TIS Divisional Secretariat, email Tis.Secretariat@cern.ch.

  11. SAFETY INSTRUCTION NO 48 (IS48)

    CERN Multimedia

    TIS Secretariat

    2001-01-01

    Please note that the Safety Instruction no 48 (IS48) entitled 'FIRE PREVENTION FOR CABLES, CABLE TRAYS AND CONDUITS'   is available on the web at the following url: Fire Prevention Paper copies can also be obtained from the TIS Divisional Secretariat, email Tis.Secretariat@cern.ch.

  12. Simulation of vanadium-48 production using MCNPX code

    Directory of Open Access Journals (Sweden)

    Sadeghi Mahdi

    2012-01-01

    Full Text Available Vanadium-48 was produced through the irradiation of the natural titanium target via the natTi(p, xn48V reaction. The titanium target was irradiated at 1 mA current and by a 21 MeV proton beam for 4 hours. In this paper, the activity of 48V, 43Sc, and 46Sc radionuclides and the efficacy of the 47Ti(p, g, 48Ti(p, n, and 49Ti(p, 2n channel reactions to form 48V radionuclide were determined using MCNPX code. Furthermore, the experimental activity of 48V was compared with the estimated value for the thick target yield produced in the irradiation time according to MCNPX code. Good agreement between production yield of the 48V and the simulation yield was observed. In conclusion, MCNPX code can be used for the estimation of the production yield.

  13. Calcium-Sensitive MRI Contrast Agents Based on Superparamagnetic Iron Oxide Nanoparticles and Calmodulin

    National Research Council Canada - National Science Library

    Tatjana Atanasijevic; Maxim Shusteff; Peter Fam; Alan Jasanoff

    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 calciumsensing protein calmodulin and its targets...

  14. Hybrid calcium phosphate coatings for implants

    Science.gov (United States)

    Malchikhina, Alena I.; Shesterikov, Evgeny V.; Bolbasov, Evgeny N.; Ignatov, Viktor P.; Tverdokhlebov, Sergei I.

    2016-08-01

    Monophasic biomaterials cannot provide all the necessary functions of bones or other calcined tissues. It is necessary to create for cancer patients the multiphase materials with the structure and composition simulating the natural bone. Such materials are classified as hybrid, obtained by a combination of chemically different components. The paper presents the physical, chemical and biological studies of coatings produced by hybrid technologies (HT), which combine primer layer and calcium phosphate (CaP) coating. The first HT type combines the method of vacuum arc titanium primer layer deposition on a stainless steel substrate with the following micro-arc oxidation (MAO) in phosphoric acid solution with addition of calcium compounds to achieve high supersaturated state. MAO CaP coatings feature high porosity (2-8%, pore size 5-7 µm) and surface morphology with the thickness greater than 5 µm. The thickness of Ti primer layer is 5-40 µm. Amorphous MAO CaP coating micro-hardness was measured at maximum normal load Fmax = 300 mN. It was 3.1 ± 0.8 GPa, surface layer elasticity modulus E = 110 ± 20 GPa, roughness Ra = 0.9 ± 0.1 µm, Rz = 7.5 ± 0.2 µm, which is less than the titanium primer layer roughness. Hybrid MAO CaP coating is biocompatible, able to form calcium phosphates from supersaturated body fluid (SBF) solution and also stimulates osteoinduction processes. The second HT type includes the oxide layer formation by thermal oxidation and then CaP target radio frequency magnetron sputtering (RFMS). Oxide-RFMS CaP coating is a thin dense coating with good adhesion to the substrate material, which can be used for metal implants. The RFMS CaP coating has thickness 1.6 ± 0.1 µm and consists of main target elements calcium and phosphorus and Ca/P ratio 2.4. The second HT type can form calcium phosphates from SBF solution. In vivo study shows that hybrid RFMS CaP coating is biocompatible and produces fibrointegration processes.

  15. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000490.htm Calcium, vitamin D, and your bones To use the sharing ... and maintain strong bones. How Much Calcium and Vitamin D do I Need? Amounts of calcium are ...

  16. Calcium Supplements: Do Men Need Them Too?

    Science.gov (United States)

    ... Lifestyle Nutrition and healthy eating Should men take calcium supplements? Answers from Katherine Zeratsky, R.D., L. ... Most healthy men don't need to take calcium supplements. Calcium is important for men for optimal ...

  17. Dietary calcium supplementation enhances efficacy but also toxicity of EGFR inhibitor therapy for colon cancer.

    Science.gov (United States)

    Rinella, Erica S; Bankaitis, Eric D; Threadgill, David W

    2012-02-01

    The inverse correlation between levels of dietary calcium and colorectal cancer (CRC) incidence has been extensively investigated. However, the impact of supplemental calcium on cancer therapy remains unknown. We used four models of CRC, Caco-2 and HCT116 human cancer cell lines and Apc (Min/+) and azoxymethane carcinogen-induced mouse models, to investigate the impact of a western-style diet low in calcium (0.05%) vs. a similar diet but supplemented with calcium (5%) on therapeutic targeting of the epidermal growth factor receptor (EGFR). We found that calcium supplementation combined with pharmacologic blockade of EGFR results in an additive effect on tumor growth inhibition in all models. Unexpectedly, the combined use of dietary calcium supplementation and EGFR inhibitors also resulted in elevated toxicity suggesting that careful consideration be given when combining dietary supplements with prescribed cancer therapies.

  18. Effect of calcium in brine on salt diffusion and water distribution of Mozzarella cheese during brining.

    Science.gov (United States)

    Luo, J; Pan, T; Guo, H Y; Ren, F Z

    2013-02-01

    A soft, pasty, high-moisture surface defect occurs with progressive brining of Mozzarella cheese. Addition of calcium is traditionally used to prevent this defect but the underlying mechanism is not clear. Mozzarella cheese was formed into a cylinder inside brine on its plane surface to ensure semi-infinite, unidirectional mass transfer and placed into brine containing 0, 0.1, or 0.25% (wt/wt) calcium chloride. To monitor the effect on cheese composition of calcium in brine, we measured calcium and water contents of the cheese during brining. The extent of calcium loss from the cheese decreased significantly with the addition of calcium. Addition of calcium to a final concentration of 0.25% decreased the loss of calcium from 94.13 to 18.22% from the outside region of the cheese after 30 d, and the water content of the cheese was decreased from 67.8 to 48.8%. To further elucidate the effect of calcium in brine, the Boltzmann method was used to determine the effective diffusion coefficient value, and low-field nuclear magnetic resonance was used to measure the cheese transversal relaxation time. The migration of calcium interfered with salt diffusion. At the end of brining, the amount of water bound to the protein of the cheese significantly increased. Addition of calcium to a final concentration of 0.25% diminished the proportion of bound water by 20.96%. In conclusion, addition of calcium hinders the diffusion of sodium and modifies the distribution of water in Mozzarella cheese during brining. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Stable prenucleation calcium carbonate clusters.

    Science.gov (United States)

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-12-19

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate in fact contains stable prenucleation ion clusters forming even in undersaturated solution. The cluster formation can be characterized by means of equilibrium thermodynamics, applying a multiple-binding model, which allows for structural preformation. Stable clusters are the relevant species in calcium carbonate nucleation. Such mechanisms may also be important for the crystallization of other minerals.

  20. A toxin from the spider Phoneutria nigriventer that blocks calcium channels coupled to exocytosis

    Science.gov (United States)

    Guatimosim, C; Romano-Silva, M A; Cruz, J S; Beirão, P S L; Kalapothakis, E; Moraes-Santos, T; Cordeiro, M N; Diniz, C R; Gomez, M V; Prado, M A M

    1997-01-01

    The aim of the present experiments was to investigate the pharmacological action of a toxin from the spider Phoneutria nigriventer, Tx3-3, on the function of calcium channels that control exocytosis of synaptic vesicles. Tx3-3, in confirmation of previous work, diminished the intracellular calcium increase induced by membrane depolarization with KCl (25 mM) in rat cerebrocortical synaptosomes. The toxin was very potent (IC50 0.9 nM) at inhibiting calcium channels that regulate calcium entry in synaptosomes. In addition, Tx3-3 blocked the exocytosis of synaptic vesicles, as measured with the fluorescent dye FM1-43. Using ω-toxins that interact selectively with distinct neuronal calcium channels, we investigated whether the target of Tx3-3 overlaps with known channels that mediate exocytosis. The results indicate that the main population of voltage-sensitive calcium channels altered by Tx3-3 can also be inhibited by ω-agatoxin IVA, an antagonist of P/Q calcium channels. ω-conotoxin GVIA, which inhibits N type calcium channels did not decrease significantly the entry of calcium or exocytosis of synaptic vesicles in depolarized synaptosomes. It is concluded that Tx3-3 potently inhibits ω-agatoxin IVA-sensitive calcium channels, which are involved in controlling exocytosis in rat brain cortical synaptosomes. PMID:9351520

  1. Calcium metabolism & hypercalcemia in adults.

    Science.gov (United States)

    Lumachi, F; Motta, R; Cecchin, D; Ave, S; Camozzi, V; Basso, S M M; Luisetto, G

    2011-01-01

    Calcium is essential for many metabolic process, including nerve function, muscle contraction, and blood clotting. The metabolic pathways that contribute to maintain serum calcium levels are bone remodeling processes, intestinal absorption and secretion, and renal handling, but hypercalcemia occurs when at least 2 of these 3 metabolic pathways are altered. Calcium metabolism mainly depends on the activity of parathyroid hormone (PTH). Its secretion is strictly controlled by the ionized serum calcium levels through a negative feed-back, which is achieved by the activation of calcium-sensing receptors (CaSRs) mainly expressed on the surface of the parathyroid cells. The PTH receptor in bone and kidney is now referred as PTHR1. The balance of PTH, calcitonin, and vitamin D has long been considered the main regulator of calcium metabolism, but the function of other actors, such as fibroblast growth factor-23 (FGF-23), Klotho, and TPRV5 should be considered. Primary hyperparathyroidism and malignancy are the most common causes of hypercalcemia, accounting for more than 90% of cases. Uncontrolled hypercalcemia may cause renal impairment, both temporary (alteration of renal tubular function) and progressive (relapsing nephrolithiasis), leading to a progressive loss of renal function, as well as severe bone diseases, and heart damages. Advances in the understanding of all actors of calcium homeostasis will be crucial, having several practical consequences in the treatment and prevention of hypercalcemia. This would allow to move from a support therapy, sometimes ineffective, to a specific and addressed therapy, especially in patients with chronic hypercalcemic conditions unsuitable for surgery.

  2. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... Duyff RL. American Dietetic Association Complete Food and Nutrition Guide. 4th ed. Hoboken, N.J.: John Wiley & Sons; 2012:140. Rosen HN. Calcium and vitamin D supplementation in osteoporosis. http://www.uptodate.com/home/index. ...

  3. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    Science.gov (United States)

    Gooding, J. L.; Wentworth, S. J.

    1987-01-01

    Chips of glassy Lithology C of EETA79001 were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy to determine the mineralogy and petrogenesis of the glass that was shown by others to contain trapped Mars-like gases. Calcium carbonite was identified as massive to acicular crystals for which Ca, C, and O were the major elements. Calcium sulfate was identified as prismatic-acicular crystals with Ca and S as the major elements.

  4. Effects of various diets on the calcium and phosphorus composition of mealworms (Tenebrio molitor larvae) and superworms (Zophobas morio larvae).

    Science.gov (United States)

    Latney, La'Toya V; Toddes, Barbara D; Wyre, Nicole R; Brown, Dorothy C; Michel, Kathryn E; Briscoe, Johanna A

    2017-02-01

    OBJECTIVE To evaluate whether the nutritive quality of Tenebrio molitor larvae and Zophobas morio larvae, which are commonly cultured as live food sources, is influenced by 4 commercially available diets used as nutritional substrates; identify which diet best improved calcium content of larvae; and identify the feeding time interval that assured the highest calcium intake by larvae. ANIMALS 2,000 Zophobas morio larvae (ie, superworms) and 7,500 Tenebrio molitor larvae (ie, mealworms). PROCEDURES Larvae were placed in control and diet treatment groups for 2-, 7-, and 10-day intervals. Treatment diets were as follows: wheat millings, avian hand feeding formula, organic avian mash diet, and a high-calcium cricket feed. Control groups received water only. After treatment, larvae were flash-frozen live with liquid nitrogen in preparation for complete proximate and mineral analyses. Analyses for the 2-day treatment group were performed in triplicate. RESULTS The nutrient composition of the high-calcium cricket feed groups had significant changes in calcium content, phosphorus content, and metabolizable energy at the 2-day interval, compared with other treatment groups, for both mealworms and superworms. Calcium content and calcium-to-phosphorus ratios for larvae in the high-calcium cricket feed group were the highest among the diet treatments for all treatment intervals and for both larval species. CONCLUSIONS AND CLINICAL RELEVANCE A 2-day interval with the high-calcium cricket feed achieved a larval nutrient composition sufficient to meet National Research Council dietary calcium recommendations for nonlactating rats. Mealworm calcium composition reached 2,420 g/1,000 kcal at 48 hours, and superworm calcium composition reached 2,070g/1,000 kcal at 48 hours. These findings may enable pet owners, veterinarians, insect breeders, and zoo curators to optimize nutritive content of larvae fed to insectivorous animals.

  5. Layer-by-layer assembled magnetic prednisolone microcapsules (MPC) for controlled and targeted drug release at rheumatoid arthritic joints

    Science.gov (United States)

    Prabu, Chakkarapani; Latha, Subbiah; Selvamani, Palanisamy; Ahrentorp, Fredrik; Johansson, Christer; Takeda, Ryoji; Takemura, Yasushi; Ota, Satoshi

    2017-04-01

    We report here in about the formulation and evaluation of Magnetic Prednisolone Microcapsules (MPC) developed in order to improve the therapeutic efficacy relatively at a low dose than the conventional dosage formulations by means of magnetic drug targeting and thus enhancing bioavailability at the arthritic joints. Prednisolone was loaded to poly (sodium 4-styrenesulfonate) (PSS) doped calcium carbonate microspheres confirmed by the decrease in surface area from 97.48 m2/g to 12.05 of m2/g by BET analysis. Adsorption with oppositely charged polyelectrolytes incorporated with iron oxide nanoparticles was confirmed through zeta analysis. Removal of calcium carbonate core yielded MPC with particle size of 3.48 μm, zeta potential of +29.7 mV was evaluated for its magnetic properties. Functional integrity of MPC was confirmed through FT-IR spectrum. Stability studies were performed at 25 °C±65% relative humidity for 60 days showed no considerable changes. Further the encapsulation efficiency of 63%, loading capacity of 18.2% and drug release of 88.3% for 36 h and its kinetics were also reported. The observed results justify the suitability of MPC for possible applications in the magnetic drug targeting for efficient therapy of rheumatoid arthritis.

  6. 21 CFR 184.1187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH control...

  7. Extracellular and Intracellular Regulation of Calcium Homeostasis

    Directory of Open Access Journals (Sweden)

    Felix Bronner

    2001-01-01

    Full Text Available An organism with an internal skeleton must accumulate calcium while maintaining body fluids at a well-regulated, constant calcium concentration. Neither calcium absorption nor excretion plays a significant regulatory role. Instead, isoionic calcium uptake and release by bone surfaces causes plasma calcium to be well regulated. Very rapid shape changes of osteoblasts and osteoclasts, in response to hormonal signals, modulate the available bone surfaces so that plasma calcium can increase when more low-affinity bone calcium binding sites are made available and can decrease when more high-affinity binding sites are exposed. The intracellular free calcium concentration of body cells is also regulated, but because cells are bathed by fluids with vastly higher calcium concentration, their major regulatory mechanism is severe entry restriction. All cells have a calcium-sensing receptor that modulates cell function via its response to extracellular calcium. In duodenal cells, the apical calcium entry structure functions as both transporter and a vitamin D–responsive channel. The channel upregulates calcium entry, with intracellular transport mediated by the mobile, vitamin D–dependent buffer, calbindin D9K, which binds and transports more than 90% of the transcellular calcium flux. Fixed intracellular calcium binding sites can, like the body's skeleton, take up and release calcium that has entered the cell, but the principal regulatory tool of the cell is restricted entry.

  8. Calcium phosphates for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

    2017-07-01

    The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

  9. Polysulfide calcium as multyfunctional product

    Directory of Open Access Journals (Sweden)

    G. Abramova

    2012-12-01

    Full Text Available A modified method of producing of polysulfide calcium, the influence of various factors on the degree of polysulfide of product, as well as possible directions for its use as a multifunctional compound were considered.

  10. [Calcium metabolism after the menopause].

    Science.gov (United States)

    Kanovitch, D; Klotz, H P

    1976-02-16

    The authors recall the antagonism between estradiol and parathormone. Estradiol tends to lower serum calcium and fix calcium in the bones as shown by one of us 25 years ago. The mechanism of this action of estrogen on calcium metabolism has been determined by numerous authors but some points are still not clear, e.g. the interferences between estrogen and calcitonin. Classically, parathormone is known to increase bony reabsorption and raise serum calcium. After the menopause the gradual reduction in estradiol secretion leads to post-menopausal osteoporosis. It is better to administer estrogens prophylactically to women after the menopause provided a cervical smear and mammography have been carried out to eliminate latent carcinoma of the breast or uterine cervix.

  11. Calcium-sensing beyond neurotransmitters

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Han, Weiping

    2009-01-01

    Neurotransmitters, neuropeptides and hormones are released through the regulated exocytosis of SVs (synaptic vesicles) and LDCVs (large dense-core vesicles), a process that is controlled by calcium. Synaptotagmins are a family of type 1 membrane proteins that share a common domain structure. Most....... Also, we discuss potential roles of synaptotagmins in non-traditional endocrine systems....... synaptotagmins are located in brain and endocrine cells, and some of these synaptotagmins bind to phospholipids and calcium at levels that trigger regulated exocytosis of SVs and LDCVs. This led to the proposed synaptotagmin-calcium-sensor paradigm, that is, members of the synaptotagmin family function...... as calcium sensors for the regulated exocytosis of neurotransmitters, neuropeptides and hormones. Here, we provide an overview of the synaptotagmin family, and review the recent mouse genetic studies aimed at understanding the functions of synaptotagmins in neurotransmission and endocrine-hormone secretion...

  12. Induction of epithelial-mesenchymal transition (EMT) in breast cancer cells is calcium signal dependent.

    Science.gov (United States)

    Davis, F M; Azimi, I; Faville, R A; Peters, A A; Jalink, K; Putney, J W; Goodhill, G J; Thompson, E W; Roberts-Thomson, S J; Monteith, G R

    2014-05-01

    Signals from the tumor microenvironment trigger cancer cells to adopt an invasive phenotype through epithelial-mesenchymal transition (EMT). Relatively little is known regarding key signal transduction pathways that serve as cytosolic bridges between cell surface receptors and nuclear transcription factors to induce EMT. A better understanding of these early EMT events may identify potential targets for the control of metastasis. One rapid intracellular signaling pathway that has not yet been explored during EMT induction is calcium. Here we show that stimuli used to induce EMT produce a transient increase in cytosolic calcium levels in human breast cancer cells. Attenuation of the calcium signal by intracellular calcium chelation significantly reduced epidermal growth factor (EGF)- and hypoxia-induced EMT. Intracellular calcium chelation also inhibited EGF-induced activation of signal transducer and activator of transcription 3 (STAT3), while preserving other signal transduction pathways such as Akt and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. To identify calcium-permeable channels that may regulate EMT induction in breast cancer cells, we performed a targeted siRNA-based screen. We found that transient receptor potential-melastatin-like 7 (TRPM7) channel expression regulated EGF-induced STAT3 phosphorylation and expression of the EMT marker vimentin. Although intracellular calcium chelation almost completely blocked the induction of many EMT markers, including vimentin, Twist and N-cadherin, the effect of TRPM7 silencing was specific for vimentin protein expression and STAT3 phosphorylation. These results indicate that TRPM7 is a partial regulator of EMT in breast cancer cells, and that other calcium-permeable ion channels are also involved in calcium-dependent EMT induction. In summary, this work establishes an important role for the intracellular calcium signal in the induction of EMT in human breast cancer cells. Manipulation of

  13. [Excessive fluoride inducing calcium overload and apoptosis of ameloblasts].

    Science.gov (United States)

    Ying, Zhang; Lin, Ma; Jian, Li; Ming, Zhong; Kaiqiang, Zhang; Hefeng, Gu

    2014-12-01

    To study the effect of excessive fluoride on calcium overload and apoptosis in cultured rat ameloblasts in vitro. Logarithmic-phase ameloblasts (HAT-7) were treated with 0, 0.4, 0.8, 1.6, 3.2, and 6.4 mmol · L(-1) sodium fluoride (NaF) solution. Cell activities were detected by using a Cell Counting Kit 8 (CCK-8) assay after 48 h of treatment. The effect of fluoride on cell apoptosis was analyzed by using flow cytometry. Excessive fluoride-induced calcium concentration and calreticulin expression changes in ameloblasts were detected by using laser scanning confocal microscopy, Western blot analysis, and real-time quantitative polymerase chain reaction. NaF inhibited ameloblast activity at 1.6, 3.2, and 6.4 mmol · L(-1) (dose-dependent) after 48 h of induction. The Ca2+ fluorescence intensity of HAT-7 cells incubated with 1.6 and 3.2 mmol · L(-1) NaF was higher than that in the control group. The fluoride-induced early-stage apoptosis of ameloblasts after 48 h of induction and the early-stage apoptosis rate was positively correlated with fluoride concentration. Calreticulin mRNA expression in HAT-7 cells was higher than that in the control group after 48 h of incubation with 0.8, 1.2, and 1.6 mmol · L(-1) NaF. Excessive fluoride-induced calcium overload in ameloblasts and further caused endoplasmic reticulum stress-mediated apoptosis.

  14. 21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pantothenate, calcium chloride double salt. 172.330 Section 172.330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN..., calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

  15. Urine risk factors in children with calcium kidney stones and their siblings.

    Science.gov (United States)

    Bergsland, Kristin J; Coe, Fredric L; White, Mark D; Erhard, Michael J; DeFoor, William R; Mahan, John D; Schwaderer, Andrew L; Asplin, John R

    2012-06-01

    Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence, treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone-forming children, we compared chemical measurements and the crystallization properties of 24-h urine collections from 129 stone formers matched to 105 non-stone-forming siblings and 183 normal, healthy children with no family history of stones, all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH, and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

  16. Calcium affects on vascular endpoints

    Directory of Open Access Journals (Sweden)

    Patel Vaishali B

    2012-03-01

    Full Text Available Abstract Calcium is one of the most abundant minerals in the body and its metabolism is one of the basic biologic processes in humans. Although historically linked primarily to bone structural development and maintenance, calcium is now recognized as a key component of many physiologic pathways necessary for optimum health including cardiovascular, neurological, endocrine, renal, and gastrointestinal systems. A recent meta-analysis published in August 2011 showed a potential increase in cardiovascular events related to calcium supplementation. The possible mechanism of action of this correlation has not been well elucidated. This topic has generated intense interest due to the widespread use of calcium supplements, particularly among the middle aged and elderly who are at the most risk from cardiac events. Prior studies did not control for potential confounding factors such as the use of statins, aspirin or other medications. These controversial results warrant additional well-designed studies to investigate the relationship between calcium supplementation and cardiovascular outcomes. The purpose of this review is to highlight the current literature in regards to calcium supplementation and cardiovascular health; and to identify areas of future research.

  17. Masses of exotic calcium isotopes pin down nuclear forces.

    Science.gov (United States)

    Wienholtz, F; Beck, D; Blaum, K; Borgmann, Ch; Breitenfeldt, M; Cakirli, R B; George, S; Herfurth, F; Holt, J D; Kowalska, M; Kreim, S; Lunney, D; Manea, V; Menéndez, J; Neidherr, D; Rosenbusch, M; Schweikhard, L; Schwenk, A; Simonis, J; Stanja, J; Wolf, R N; Zuber, K

    2013-06-20

    The properties of exotic nuclei on the verge of existence play a fundamental part in our understanding of nuclear interactions. Exceedingly neutron-rich nuclei become sensitive to new aspects of nuclear forces. Calcium, with its doubly magic isotopes (40)Ca and (48)Ca, is an ideal test for nuclear shell evolution, from the valley of stability to the limits of existence. With a closed proton shell, the calcium isotopes mark the frontier for calculations with three-nucleon forces from chiral effective field theory. Whereas predictions for the masses of (51)Ca and (52)Ca have been validated by direct measurements, it is an open question as to how nuclear masses evolve for heavier calcium isotopes. Here we report the mass determination of the exotic calcium isotopes (53)Ca and (54)Ca, using the multi-reflection time-of-flight mass spectrometer of ISOLTRAP at CERN. The measured masses unambiguously establish a prominent shell closure at neutron number N = 32, in excellent agreement with our theoretical calculations. These results increase our understanding of neutron-rich matter and pin down the subtle components of nuclear forces that are at the forefront of theoretical developments constrained by quantum chromodynamics.

  18. Masses of exotic calcium isotopes pin down nuclear forces

    CERN Document Server

    Wienholtz, F; Blaum, K; Borgmann, Ch; Breitenfeldt, M; Cakirli, R B; George, S; Herfurth, F; Holt, J D; Kowalska, M; Kreim, S; Lunney, D; Manea, V; Menéndez, J; Neidherr, D; Rosenbusch, M; Schweikhard, L; Schwenk, A; Simonis, J; Stanja, J; Wolf, R N; Zuber, K

    2013-01-01

    The properties of exotic nuclei on the verge of existence play a fundamental part in our understanding of nuclear interactions. Exceedingly neutron-rich nuclei become sensitive to new aspects of nuclear forces. Calcium, with its doubly magic isotopes $^{40}$Ca and $^{48}$Ca, is an ideal test for nuclear shell evolution, from the valley of stability to the limits of existence. With a closed proton shell, the calcium isotopes mark the frontier for calculations with three-nucleon forces from chiral effective field theory. Whereas predictions for the masses of $^{51}$Ca and $^{52}$Ca have been validated by direct measurements$^4$, it is an open question as to how nuclear masses evolve for heavier calcium isotopes. Here we report the mass determination of the exotic calcium isotopes $^{53}$Ca and $^{54}$Ca, using the multi-reflection time-of-flight mass spectrometer of ISOLTRAP at CERN. The measured masses unambiguously establish a prominent shell closure at neutron number N = 32, in excellent agreement with our t...

  19. Target Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — [Part of the ATLAS user facility.] The Physics Division operates a target development laboratory that produces targets and foils of various thickness and substrates,...

  20. Calcium: the molecular basis of calcium action in biology and medicine

    National Research Council Canada - National Science Library

    Pochet, Roland; Donato, Rosario

    2000-01-01

    ... of Calcium Calcium Signalling in Excitable Cells Ca2+ Release in Muscle Cells by N. Macrez and J. Mironneau Calcium Signalling in Neurons Exemplified by Rat Sympathetic Ganglion Cells by S.J. M...

  1. Extracellular magnesium decreases the secretory response of rat peritoneal mast cells to compound 48/80 in vitro

    DEFF Research Database (Denmark)

    Bertelsen, Niels Haldor; Johansen, Torben

    1991-01-01

    Exposure of rat peritoneal mast cells to magnesium in the absence of extracellular calcium resulted in a time- and dose-dependent decrease in the secretory response induced by compound 48/80. The decrease was prevented by a low extracellular concentration of calcium. Furthermore, the decreased...... and the secretory stimulus. A dose-dependent decrease in antigen induced histamine secretion that was reversed by calcium was also observed. Exposure of the mast cells to magnesium for 15 min resulted in a parallel decrease in histamine secretion and in the cellular content of 45Ca2+. These observations suggest...... secretory responsiveness was dose-dependently restored by the addition of calcium to the cells simultaneously with compound 48/80. Preincubation with magnesium also inhibited antigen-induced histamine secretion in a dose-dependent manner. This was reversed by the simultaneous addition of calcium...

  2. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

    Thomsen, Louiza Bohn; Jörntell, Henrik; Midtgaard, Jens

    2010-01-01

    Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX....... Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon...... appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1 s...

  3. Association of Calcium-Sensing Receptor (CASR rs 1801725 with Colorectal Cancer

    Directory of Open Access Journals (Sweden)

    Fateme Rostami

    2012-07-01

    Full Text Available Background: Calcium induces apoptosis in intestinal epithelial cells and subsequently prevents colorectal cancer through ion calcium receptor. Calcium-sensing receptor mutation reduces the expression of this receptor, and subsequently in reduces calcium transportation. Many studies have shown that Calcium-sensing receptor gene polymorphism may increase the risk of colorectal cancer. The purpose of this study is to assess the prevalence of calcium-sensing receptor polymorphisms (rs 1801725 in Iran society and to examine the role of this polymorphism in the increased risk of colorectal cancer (CRC.Materials and Methods: The research was a case-control study. 105 patients with colorectal cancer and 105 controls were randomly studied using polymerase chain reaction and restriction fragment length polymorphism. χ2 test and software 16- SPSS were used for statistical analysis.Results: In patient samples, the frequency of the genotypes TT, GT, GG in gene CASR rs 1801725 was respectively 64.8, 32.4, and 2.9 and the frequency of this polymorphism in control samples was respectively 51.2, 45.7, and 2.9. Frequency of allele G in patient samples was 0/48 and frequency of allele T was 0.25. In addition, Frequency of allele G in control samples was 0.74 and Frequency of allele T was calculated 0.19.Conclusion: The results show that calcium-sensing receptor variant (1801725 rs is not associated with increased risk of colorectal cancer.

  4. Evaluation of antibacterial effects of different calcium hydroxide compositions on planktonic Enterococcus faecalis

    Directory of Open Access Journals (Sweden)

    Mahdi Tabrizizadeh

    2012-01-01

    Full Text Available Background and Aims: Calcium hydroxide has a pronounced antimicrobial activity against most of the bacterial species found in infected root canals and endodontic infections. It is one of the most frequently used intracanal medications in endodontic therapy. The objective of this study was to determine the antimicrobial efficacy of six calcium hydroxide formulations (mixed with saline, lidocaine 2%, chlorhexidine 2%, chlorhexidine 0.2%, Iodine Potassium iodide (IKI 2%, and glycerin on Enterococcus faecalis using agar diffusion test.Materials and Methods: Twelve culture plates were incubated with Enterococcus faecalis. Five cavities were made in each plate with 5 mm diameter and 4 mm depth. Two plates were randomly considered for each calcium hydroxide formulation and filled completely with creamy mixture of tested materials. The plates were incubated at 37ºC for 48 hours. The diameter of inhibition zone around each well was recorded in millimetres and data were submitted to ANOVA and Tukey tests.Results: The results of this study showed that all tested calcium hydroxide pastes had good antimicrobial activity. The antimicrobial activity of calcium hydroxide mixed with lidocaine, chlorhexidine 2% and IKI 2% were significantly greater than that of calcium hydroxide mixed with saline (P0.01.Conclusion: Considering the results of this study, lidocaine 2%, chlorhexidine 2% and IKI 2% are suggested to be used for preparation of calcium hydroxide paste. Further studies with different methods are needed for confirming these results.

  5. The genetic background affects the vascular response in T-type calcium channels 3.2 deficient mice

    DEFF Research Database (Denmark)

    Svenningsen, Per; Hansen, Pernille B L

    2016-01-01

    Voltage-gated calcium channels (Cav ) are important regulators of vascular tone and are attractive targets for pharmacological treatment of hypertension. The clinical used calcium blockers are often not selective for one channel but affect several types of calcium channels (Hansen 2015). L......-type channels are the dominant Ca(2+) entry pathway in vascular smooth muscle cells, however, T-type calcium channels are also expressed in the cardiovascular system where they play a functional role in the regulation of both contraction and vasodilation in (Chen et al. 2003; Hansen et al. 2001). This article...... is protected by copyright. All rights reserved....

  6. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P parathyroid hormone levels (P animals (P = 0.057). However, mean arterial pressure was elevated (P animals fed low- compared with high-calcium diets (P parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  7. [Regulatory mechanism of calcium metabolism.

    Science.gov (United States)

    Ozono, Keiichi

    It is often difficult for terrestrial animals to take enough calcium. To maintain serum or extracellular calcium levels is very important for muscle and nerve function. Two major regulators to increase the serum calcium levels are parathyroid hormone(PTH)and vitamin D. PTH binds to the G protein coupling receptor, PTH1R, and increases intracellular cAMP levels. Impirement in the PTH signalling causes many diseases such as pseudohypoparathyroidism and acrodysostosis with hormone resistance. Vitamin D is activated to 1,25-dihydroxyvitamin D[1,25(OH)2D]by two steps of hydroxylation which occurs in the Liver and Kidney. Then, 1,25(OH)2D binds to vitamin D receptor(VDR), which works as a ligand-dependent transcription factor. Hypocalcemia and hypercalcemia are caused by various disorders including abnormal regulation of PTH and vitamin D production and their signal transduction.

  8. Calcium signaling and cell proliferation.

    Science.gov (United States)

    Pinto, Mauro Cunha Xavier; Kihara, Alexandre Hiroaki; Goulart, Vânia A M; Tonelli, Fernanda M P; Gomes, Katia N; Ulrich, Henning; Resende, Rodrigo R

    2015-11-01

    Cell proliferation is orchestrated through diverse proteins related to calcium (Ca(2+)) signaling inside the cell. Cellular Ca(2+) influx that occurs first by various mechanisms at the plasma membrane, is then followed by absorption of Ca(2+) ions by mitochondria and endoplasmic reticulum, and, finally, there is a connection of calcium stores to the nucleus. Experimental evidence indicates that the fluctuation of Ca(2+) from the endoplasmic reticulum provides a pivotal and physiological role for cell proliferation. Ca(2+) depletion in the endoplasmatic reticulum triggers Ca(2+) influx across the plasma membrane in an phenomenon called store-operated calcium entries (SOCEs). SOCE is activated through a complex interplay between a Ca(2+) sensor, denominated STIM, localized in the endoplasmic reticulum and a Ca(2+) channel at the cell membrane, denominated Orai. The interplay between STIM and Orai proteins with cell membrane receptors and their role in cell proliferation is discussed in this review. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Calcium regulation of muscle contraction.

    Science.gov (United States)

    Szent-Györgyi, A G

    1975-07-01

    Calcium triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin. Two different regulatory systems are found in different muscles. In actin-linked regulation troponin and tropomyosin regulate actin by blocking sites on actin required for complex formation with myosin; in myosin-linked regulation sites on myosin are blocked in the absence of calcium. The major features of actin control are as follows: there is a requirement for tropomyosin and for a troponin complex having three different subunits with different functions; the actin displays a cooperative behavior; and a movement of tropomyosin occurs controlled by the calcium binding on troponin. Myosin regulation is controlled by a regulatory subunit that can be dissociated in scallop myosin reversibly by removing divalent cations with EDTA. Myosin control can function with pure actin in the absence of tropomyosin. Calcium binding and regulation of molluscan myosins depend on the presence of regulatory light chains. It is proposed that the light chains function by sterically blocking myosin sites in the absence of calcium, and that the "off" state of myosin requires cooperation between the two myosin heads. Both myosin control and actin control are widely distributed in different organisms. Many invertebrates have muscles with both types of regulation. Actin control is absent in the muscles of molluscs and in several minor phyla that lack troponin. Myosin control is not found in striated vertebrate muscles and in the fast muscles of crustacean decapods, although regulatory light chains are present. While in vivo myosin control may not be excluded from vertebrate striated muscles, myosin control may be absent as a result of mutations of the myosin heavy chain.

  10. Nuclear Calcium Signaling Induces Expression of the Synaptic Organizers Lrrtm1 and Lrrtm2*

    Science.gov (United States)

    Hayer, Stefanie N.; Bading, Hilmar

    2015-01-01

    Calcium transients in the cell nucleus evoked by synaptic activity in hippocampal neurons function as a signaling end point in synapse-to-nucleus communication. As an important regulator of neuronal gene expression, nuclear calcium is involved in the conversion of synaptic stimuli into functional and structural changes of neurons. Here we identify two synaptic organizers, Lrrtm1 and Lrrtm2, as targets of nuclear calcium signaling. Expression of both Lrrtm1 and Lrrtm2 increased in a synaptic NMDA receptor- and nuclear calcium-dependent manner in hippocampal neurons within 2–4 h after the induction of action potential bursting. Induction of Lrrtm1 and Lrrtm2 occurred independently of the need for new protein synthesis and required calcium/calmodulin-dependent protein kinases and the nuclear calcium signaling target CREB-binding protein. Analysis of reporter gene constructs revealed a functional cAMP response element in the proximal promoter of Lrrtm2, indicating that at least Lrrtm2 is regulated by the classical nuclear Ca2+/calmodulin-dependent protein kinase IV-CREB/CREB-binding protein pathway. These results suggest that one mechanism by which nuclear calcium signaling controls neuronal network function is by regulating the expression of Lrrtm1 and Lrrtm2. PMID:25527504

  11. Nuclear calcium signaling induces expression of the synaptic organizers Lrrtm1 and Lrrtm2.

    Science.gov (United States)

    Hayer, Stefanie N; Bading, Hilmar

    2015-02-27

    Calcium transients in the cell nucleus evoked by synaptic activity in hippocampal neurons function as a signaling end point in synapse-to-nucleus communication. As an important regulator of neuronal gene expression, nuclear calcium is involved in the conversion of synaptic stimuli into functional and structural changes of neurons. Here we identify two synaptic organizers, Lrrtm1 and Lrrtm2, as targets of nuclear calcium signaling. Expression of both Lrrtm1 and Lrrtm2 increased in a synaptic NMDA receptor- and nuclear calcium-dependent manner in hippocampal neurons within 2-4 h after the induction of action potential bursting. Induction of Lrrtm1 and Lrrtm2 occurred independently of the need for new protein synthesis and required calcium/calmodulin-dependent protein kinases and the nuclear calcium signaling target CREB-binding protein. Analysis of reporter gene constructs revealed a functional cAMP response element in the proximal promoter of Lrrtm2, indicating that at least Lrrtm2 is regulated by the classical nuclear Ca(2+)/calmodulin-dependent protein kinase IV-CREB/CREB-binding protein pathway. These results suggest that one mechanism by which nuclear calcium signaling controls neuronal network function is by regulating the expression of Lrrtm1 and Lrrtm2. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Overlevelse efter massiv verapamiloverdosis hos en 48-årig kvinde

    DEFF Research Database (Denmark)

    Johansen, Karina K; Belhage, Bo

    2007-01-01

    We present a case report of survival from a massive verapamil overdose. The patient, a 48-year-old female, was admitted 12 hours after suicidal ingestion of 10.08 grams of Isoptin Retard, a sustained release calcium channel blocker. On admittance, the patient had altered mental status, was hypote......We present a case report of survival from a massive verapamil overdose. The patient, a 48-year-old female, was admitted 12 hours after suicidal ingestion of 10.08 grams of Isoptin Retard, a sustained release calcium channel blocker. On admittance, the patient had altered mental status...

  13. Can total cardiac calcium predict the coronary calcium score?

    Science.gov (United States)

    Pressman, Gregg S; Crudu, Vitalie; Parameswaran-Chandrika, Anoop; Romero-Corral, Abel; Purushottam, Bhaskar; Figueredo, Vincent M

    2011-01-21

    Mitral annular calcification (MAC) shares the same risk factors as atherosclerosis and is associated with coronary artery disease as well as cardiovascular events. However, sensitivity and positive predictive value are low. We hypothesized that a global echocardiographic calcium score would better predict coronary atherosclerotic burden, as assessed by coronary artery calcium score (CAC), than MAC alone. An echocardiographic score was devised to measure global cardiac calcification in a semi-quantitative manner; this included calcification in the aortic valve and root, the mitral valve and annulus, and the sub-mitral apparatus. This score, and a simplified version, were compared with a similar calcification score by CT scan, as well as the CAC. There was a good correlation between the two global calcification scores; the echocardiographic score also correlated with CAC. Using CAC >400 as a measure of severe coronary atherosclerosis, an echocardiographic score ≥5 had a positive predictive value of 60%. Importantly, the simplified score performed equally well (≥3 had a positive predictive value of 62%). Global cardiac calcification, assessed by CT scan or echocardiography, correlates with the extent of coronary calcium. A semi-quantitative calcium score can be easily applied during routine echocardiographic interpretation and can alert the reader to the possibility of severe coronary atherosclerosis. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  14. Calcium ferrite formation from the thermolysis of calcium tris (maleato)

    Indian Academy of Sciences (India)

    stoichiometric quantities of aqueous solutions of calcium maleate, iron(III) maleate and maleic acid. The reaction mixture was concentrated on a water bath until a brown coloured product formed after the addition of excess of acetone. The complex was vacuum dried and its identity was established by chemical analysis.

  15. Calcium ferrite formation from the thermolysis of calcium tris ...

    Indian Academy of Sciences (India)

    Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to 900°C and ferrite formation. Three consecutive decomposition steps leading to the formation of -Fe2O3 and calcium carbonate have been observed at various stages of ...

  16. Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

    Directory of Open Access Journals (Sweden)

    Dmitry eSamigullin

    2015-01-01

    Full Text Available At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 рА and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 µM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

  17. Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

    Science.gov (United States)

    Kevin T. Smith; Walter C. Shortle; Jon H. Connolly; Rakesh Minocha; Jody Jellison

    2009-01-01

    Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of...

  18. Calcium release from experimental dental materials.

    Science.gov (United States)

    Okulus, Zuzanna; Buchwald, Tomasz; Voelkel, Adam

    2016-11-01

    The calcium release from calcium phosphate-containing experimental dental restorative materials was examined. The possible correlation of ion release with initial calcium content, solubility and degree of curing (degree of conversion) of examined materials was also investigated. Calcium release was measured with the use of an ion-selective electrode in an aqueous solution. Solubility was established by the weighing method. Raman spectroscopy was applied for the determination of the degree of conversion, while initial calcium content was examined with the use of energy-dispersive spectroscopy. For examined materials, the amount of calcium released was found to be positively correlated with solubility and initial calcium content. It was also found that the degree of conversion does not affect the ability of these experimental composites to release calcium ions. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Familial hypocalciuric hypercalcemia and calcium sensing receptor

    DEFF Research Database (Denmark)

    Mrgan, Monija; Nielsen, Sanne; Brixen, Kim

    2014-01-01

    Familial hypocalciuric hypercalcemia (FHH) is a lifelong, benign autosomal dominant disease characterized by hypercalcemia, normal to increased parathyroid hormone level, and a relatively low renal calcium excretion. Inactivation of the calcium-sensing receptor in heterozygous patients results in...

  20. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... Bone Health Featured Resource Find an Endocrinologist Search Vitamin D, Calcium, and Bone Health March 2012 Download ... also helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin ...

  1. [Pathophysiology, diagnosis and conservative therapy in calcium kidney calculi].

    Science.gov (United States)

    Hess, B

    2003-02-01

    pilots) as well as in all recurrent stone formers, an extended metabolic evaluation should be performed. Two 24-hurines should be collected on free-choice diet not prior to three months after stone passage or urological intervention. Analysis includes measurements of volume, creatinine, calcium, oxalate, uric acid and citrate; sodium and urea as markers of salt and protein consumption are optional but clinically very helpful. Since hypercalciuria is of much less importance than increases in urinary oxalate, therapeutic efforts should primarily focus on lowering urinary oxalate excretion. Sufficient calcium intake, i.e. 1200 mg per day, is crucial, because it allows for binding of oxalate at the intestinal level whereby increases of urinary oxalate (reciprocal hyperoxaluria) can be avoided. Excess intake of flesh protein (meat, fish, poultry) is lithogenic since it increases urinary calcium, oxalate and uric acid, and lower citrate. On the other hand, a diet rich in alkali (vegetables, fruit) is associated with a lower risk of stone formation. A "common sense diet" containing sufficient amounts of fluids, 1200 mg of calcium per day and reduced amounts of flesh protein as well as salt is able to reduce the 5-year stone recurrence rate in calcium stone formers by 50%. The scientific evidence for drug treatment (thiazides, alkali citrate) is rather poor: the most widely quoted randomized thiazide trial included only 42 patients of whom 36% left the protocol prematurely, whereas 36-48% of patients included in three randomized studies with alkali citrate suffered from undesirable side-effects; nevertheless, citrate therapy reduced the stone recurrence rate by 38%, compared with 22% in patients on placebo treatment (p < 0.0005).

  2. 21 CFR 184.1229 - Calcium stearate.

    Science.gov (United States)

    2010-04-01

    ... Specific Substances Affirmed as GRAS § 184.1229 Calcium stearate. (a) Calcium stearate (Ca(C17H35COO)2, CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium stearate. 184.1229 Section 184.1229 Food...

  3. Bioactive and Hemocompatible Calcium Sulphoaluminate Cement

    OpenAIRE

    Acuña-Gutiérrez, Iván Omar; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Cortés-Hernández, Dora Alicia; Saldívar-Ramírez, Mirna María Guadalupe; Reséndiz-Hernández, Perla Janet; Zugasti-Cruz, Alejandro

    2015-01-01

    Calcium sulphoaluminate cement (CSAC) is an attractive candidate for biomedical applications due to its appropriate mechanical properties and high calcium content. In vitro bioactivity and hemocompatibility of calcium sulphoaluminate cement were assessed. The cement was prepared from a mixture of calcium sulphoaluminate (CSA) clinker, gypsum and water. Cement samples were immersed in a simulated body fluid (SBF) at 37 °C for different periods of time (7, 14 and 21 days). The analyses of these...

  4. Calcium Balance in Chronic Kidney Disease

    OpenAIRE

    Hill Gallant, Kathleen M.; Spiegel, David M.

    2017-01-01

    Purpose of Review The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balan...

  5. Calcium Balance in Chronic Kidney Disease.

    Science.gov (United States)

    Hill Gallant, Kathleen M; Spiegel, David M

    2017-06-01

    The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

  6. Electrochemical Induced Calcium Phosphate Precipitation

    NARCIS (Netherlands)

    Lei, Yang; Song, Bingnan; Weijden, van der Renata D.; Saakes, M.; Buisman, Cees J.N.

    2017-01-01

    Phosphorus (P) is an essential nutrient for living organisms and cannot be replaced or substituted. In this paper, we present a simple yet efficient membrane free electrochemical system for P removal and recovery as calcium phosphate (CaP). This method relies on in situ formation of hydroxide

  7. Synthesis and characterization of biodegradable microcapsules for the controlled delivery of calcium hydroxide.

    Science.gov (United States)

    Han, Bing; Wang, Xiaoyan; Gao, Xuejun; Liu, Jiguang; Liang, Fuxin; Qu, Xiaozhong; Yang, Zhenzhong

    2011-10-01

    This study aimed to synthesize and characterize biodegradable microcapsules based on poly(lactic acid) (PLA) and ethylcellulose (EC) for a controlled delivery of calcium hydroxide. Phase separation technique was adopted to synthesize calcium hydroxide-loaded PLA/EC microcapsules. Four PLA/EC blends (4/1, 1/1, 1/4, pure EC) were used as shell materials and the input ratio of calcium hydroxide to shell polymer was 4:1 for all microcapsules. The morphology and composition were studied using SEM-EDS and TEM. Particle size distribution, glass-transition temperature, drug loading, and encapsulation efficiency were characterized. In vitro release of the microcapsules was evaluated using a pH microelectrode and an auto-biochemistry analyzer. SEM images of microcapsules showed uniform spherical structures with smooth surfaces. Core-shell, hetero-structures were confirmed using TEM. The presence of calcium in the microcapsules was verified with EDS. Pure calcium hydroxide was 160 nm in diameter and the particle size of the microcapsules ranged between 500 nm and 4 μm. With an increase of PLA in PLA/EC blend, the size of microcapsules increased accordingly. Encapsulation efficiency of these microcapsules was higher than 57% and drug loading was higher than 80%, which were not significantly different among four microcapsules. Pure calcium hydroxide powder was used as a control and 90% was released within 48 h, while release of calcium hydroxide from microcapsules took between 168 and 456 h, depending on the PLA/EC ratio. Compared with calcium hydroxide powder, the calcium hydroxide-loaded microcapsules showed a sustained and prolonged release, which could be controlled via the regulation of the PLA/EC ratio. Copyright © 2011 Wiley Periodicals, Inc.

  8. 21 CFR 582.7187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is generally...

  9. Abnormalities of serum calcium and magnesium

    Science.gov (United States)

    Neonatal hypocalcemia is defined as a total serum calcium concentration of <7 mg/dL or an ionized calcium concentration of <4 mg/dL (1mmol/L). In very low birth weight (VLBW) infants, ionized calcium values of 0.8 to 1 mmol/L are common and not usually associated with clinical symptoms. In larger in...

  10. Modularized study of human calcium signalling pathway

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    When there is an extracellular change, cells get the message either by introduction of calcium ions into ... as it precipitates phosphate, the established energy currency of cells. Prolonged high intracellular calcium ... trigger proteins upon binding with free calcium ion(s) change their confirmation to modulate enzymes and ion ...

  11. 21 CFR 582.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL...

  12. 21 CFR 582.5191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.5191 Section 582.5191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL...

  13. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Activation of receptors coupled to the phospholipase C/IP3 signalling pathway results in a rapid release of calcium from its intracellular stores, eventually leading to depletion of these stores. Calcium store depletion triggers an influx of extracellular calcium across the plasma membrane, a mechanism known as the ...

  14. Mitochondrial Calcium Sparkles Light Up Astrocytes.

    Science.gov (United States)

    MacVicar, Brian A; Ko, Rebecca W Y

    2017-02-27

    Discrete calcium signals in the fine processes of astrocytes are a recent discovery and a new mystery. In a recent issue of Neuron, Agarwal et al. (2017) report that calcium efflux from mitochondria during brief openings of the mitochondrial permeability transition pore (mPTP) contribute to calcium microdomains. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  15. 21 CFR 182.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium phosphate. 182.1217 Section 182.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b...

  16. 21 CFR 582.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.1217 Section 582.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b...

  17. ORIGINAL ARTICLES Calcium supplementation to prevent pre ...

    African Journals Online (AJOL)

    ORIGINAL ARTICLES. Calcium supplementation to prevent pre-eclampsia - a systematic review. G J Hofmeyr, A Roodt, A N Atallah, L Duley. Background. Calcium supplementation during pregnancy may prevent high blood pressure and preterm labour. Objective. To assess the effects of calcium supplementation.

  18. Calcium Orthophosphate-Based Bioceramics

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2013-09-01

    Full Text Available Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

  19. Calcium antagonists: a ready prescription for treating infectious diseases?

    Science.gov (United States)

    Clark, Kevin B; Eisenstein, Edward M; Krahl, Scott E

    2013-01-01

    Emergence of new and medically resistant pathogenic microbes continues to escalate toward worldwide public health, wild habitat, and commercial crop and livestock catastrophes. Attempts at solving this problem with sophisticated modern biotechnologies, such as smart vaccines and microbicidal and microbistatic drugs that precisely target parasitic bacteria, fungi, and protozoa, remain promising without major clinical and industrial successes. However, discovery of a more immediate, broad spectrum prophylaxis beyond conventional epidemiological approaches might take no longer than the time required to fill a prescription at your neighborhood pharmacy. Findings from a growing body of research suggest calcium antagonists, long approved and marketed for various human cardiovascular and neurological indications, may produce safe, efficacious antimicrobial effects. As a general category of drugs, calcium antagonists include compounds that disrupt passage of Ca(2+) molecules across cell membranes and walls, sequestration and mobilization of free intracellular Ca(2+), and downstream binding proteins and sensors of Ca(2+)-dependent regulatory pathways important for proper cell function. Administration of calcium antagonists alone at current therapeutically relevant doses and schedules, or with synergistic compounds and additional antimicrobial medications, figures to enhance host immunoprotection by directly altering pathogen infection sequences, life cycles, homeostasis, antibiotic tolerances, and numerous other infective, survival, and reproductive processes. Short of being miracle drugs, calcium antagonists are welcome old drugs with new tricks capable of controlling some of the most virulent and pervasive global infectious diseases of plants, animals, and humans, including Chagas' disease, malaria, and tuberculosis.

  20. Calcium sensing receptor signalling in physiology and cancer.

    Science.gov (United States)

    Brennan, Sarah C; Thiem, Ursula; Roth, Susanne; Aggarwal, Abhishek; Fetahu, Irfete Sh; Tennakoon, Samawansha; Gomes, Ana Rita; Brandi, Maria Luisa; Bruggeman, Frank; Mentaverri, Romuald; Riccardi, Daniela; Kallay, Enikö

    2013-07-01

    The calcium sensing receptor (CaSR) is a class C G-protein-coupled receptor that is crucial for the feedback regulation of extracellular free ionised calcium homeostasis. While extracellular calcium (Ca(2+)o) is considered the primary physiological ligand, the CaSR is activated physiologically by a plethora of molecules including polyamines and l-amino acids. Activation of the CaSR by different ligands has the ability to stabilise unique conformations of the receptor, which may lead to preferential coupling of different G proteins; a phenomenon termed 'ligand-biased signalling'. While mutations of the CaSR are currently not linked with any malignancies, altered CaSR expression and function are associated with cancer progression. Interestingly, the CaSR appears to act both as a tumour suppressor and an oncogene, depending on the pathophysiology involved. Reduced expression of the CaSR occurs in both parathyroid and colon cancers, leading to loss of the growth suppressing effect of high Ca(2+)o. On the other hand, activation of the CaSR might facilitate metastasis to bone in breast and prostate cancer. A deeper understanding of the mechanisms driving CaSR signalling in different tissues, aided by a systems biology approach, will be instrumental in developing novel drugs that target the CaSR or its ligands in cancer. This article is part of a Special Issue entitled: 12th European Symposium on Calcium. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Morphological Investigation of Calcium Carbonate during Ammonification-Carbonization Process of Low Concentration Calcium Solution

    OpenAIRE

    Huaigang Cheng; Xiaoxi Zhang; Huiping Song

    2014-01-01

    Ultrafine calcium carbonate is a widely used cheap additive. The research is conducted in low degree supersaturation solution in order to study the polymorphic phases’ change and its factors of the calcium carbonate precipitate in the ammonification-carbonization process of the solution with calcium. Fine particles of calcium carbonate are made in the solution containing 0.015 mol/L of Ca2+. Over 98% of the calcium carbonate precipitate without ammonification resembles the morphology of calci...

  2. Mammary-Specific Ablation of the Calcium-Sensing Receptor During Lactation Alters Maternal Calcium Metabolism, Milk Calcium Transport, and Neonatal Calcium Accrual

    Science.gov (United States)

    Mamillapalli, Ramanaiah; VanHouten, Joshua; Dann, Pamela; Bikle, Daniel; Chang, Wenhan; Brown, Edward

    2013-01-01

    To meet the demands for milk calcium, the lactating mother adjusts systemic calcium and bone metabolism by increasing dietary calcium intake, increasing bone resorption, and reducing renal calcium excretion. As part of this adaptation, the lactating mammary gland secretes PTHrP into the maternal circulation to increase bone turnover and mobilize skeletal calcium stores. Previous data have suggested that, during lactation, the breast relies on the calcium-sensing receptor (CaSR) to coordinate PTHrP secretion and milk calcium transport with calcium availability. To test this idea genetically, we bred BLG-Cre mice with CaSR-floxed mice to ablate the CaSR specifically from mammary epithelial cells only at the onset of lactation (CaSR-cKO mice). Loss of the CaSR in the lactating mammary gland did not disrupt alveolar differentiation or milk production. However, it did increase the secretion of PTHrP into milk and decreased the transport of calcium from the circulation into milk. CaSR-cKO mice did not show accelerated bone resorption, but they did have a decrease in bone formation. Loss of the mammary gland CaSR resulted in hypercalcemia, decreased PTH secretion, and increased renal calcium excretion in lactating mothers. Finally, loss of the mammary gland CaSR resulted in decreased calcium accrual by suckling neonates, likely due to the combination of increased milk PTHrP and decreased milk calcium. These results demonstrate that the mammary gland CaSR coordinates maternal bone and calcium metabolism, calcium transport into milk, and neonatal calcium accrual during lactation. PMID:23782944

  3. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    Science.gov (United States)

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of health claims related to lactose and increase in calcium absorption leading to an increase in calcium retention (ID 668) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

    DEFF Research Database (Denmark)

    Tetens, Inge

    claims in relation to lactose and increase in calcium absorption leading to an increase in calcium retention. The scientific substantiation is based on the information provided by the Member States in the consolidated list of Article 13 health claims and references that EFSA has received from Member...... States or directly from stakeholders. The food constituent that is the subject of the health claim is lactose. The Panel considers that lactose is sufficiently characterised. The claimed effect is “calcium absorption”. The target population is assumed to be the general population. The Panel notes...... between the consumption of lactose and an increase in calcium absorption leading to an increase in calcium retention....

  5. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential

    Science.gov (United States)

    Zamponi, Gerald W.; Striessnig, Joerg; Koschak, Alexandra

    2015-01-01

    Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type CaV1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (CaV3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (CaV2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., CaV1.2 and CaV1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective CaV1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson’s disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and

  6. Calcium homeostasis is altered in skeletal muscle of spontaneously hypertensive rats: cytofluorimetric and gene expression analysis.

    Science.gov (United States)

    Liantonio, Antonella; Camerino, Giulia M; Scaramuzzi, Antonia; Cannone, Maria; Pierno, Sabata; De Bellis, Michela; Conte, Elena; Fraysse, Bodvael; Tricarico, Domenico; Conte Camerino, Diana

    2014-10-01

    Hypertension is often associated with skeletal muscle pathological conditions related to function and metabolism. The mechanisms underlying the development of these pathological conditions remain undefined. Because calcium homeostasis is a biomarker of muscle function, we assessed whether it is altered in hypertensive muscles. We measured resting intracellular calcium and store-operated calcium entry (SOCE) in fast- and slow-twitch muscle fibers from normotensive Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs) by cytofluorimetric technique and determined the expression of SOCE gene machinery by real-time PCR. Hypertension caused a phenotype-dependent dysregulation of calcium homeostasis; the resting intracellular calcium of extensor digitorum longus and soleus muscles of SHRs were differently altered with respect to the related muscle of normotensive animals. In addition, soleus muscles of SHR showed reduced activity of the sarcoplasmic reticulum and decreased sarcolemmal calcium permeability at rest and after SOCE activation. Accordingly, we found an alteration of the expression levels of some SOCE components, such as stromal interaction molecule 1, calcium release-activated calcium modulator 1, and transient receptor potential canonical 1. The hypertension-induced alterations of calcium homeostasis in the soleus muscle of SHRs occurred with changes of some functional outcomes as excitability and resting chloride conductance. We provide suitable targets for therapeutic interventions aimed at counterbalancing muscle performance decline in hypertension, and propose the reported calcium-dependent parameters as indexes to predict how the antihypertensive drugs could influence muscle function. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  7. Computational study of a calcium release-activated calcium channel

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-05-01

    The naturally occurring proteins that form hole in membrane are commonly known as ion channels. They play multiple roles in many important biological processes. Deletion or alteration of these channels often leads to serious problems in the physiological processes as it controls the flow of ions through it. The proper maintenance of the flow of ions, in turn, is required for normal health. Here we have investigated the behavior of a calcium release-activated calcium ion channel with pdb entry 4HKR in Drosophila Melanogaster. The equilibrium energy as well as molecular dynamics simulation is performed first. The protein is subjected to molecular dynamics simulation to find their energy minimized value. Simulation of the protein in the environment of water and ions has given us important results too. The solvation energy is also found using Charmm potential.

  8. Unexpectedly large charge radii of neutron-rich calcium isotopes

    CERN Document Server

    Garcia Ruiz, R F; Blaum, K; Ekström, A; Frömmgen, N; Hagen, G; Hammen, M; Hebeler, K; Holt, J D; Jansen, G R; Kowalska, M; Kreim, K; Nazarewicz, W; Neugart, R; Neyens, G; Nörtershäuser, W; Papenbrock, T; Papuga, J; Schwenk, A; Simonis, J; Wendt, K A; Yordanov, D T

    2016-01-01

    Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain ‘magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-...

  9. The Calcium Wave of Vegetable Cells

    Directory of Open Access Journals (Sweden)

    TD. Geydan

    2007-08-01

    Full Text Available Calcium is an essential nutrient for plants; it is involved in developmental processes and in responses to biotic and abiotic factors. Several signals that modify the calcium concentration in the cytoplasm, endoplasmic reticulum, nucleus and/or plastids have been observed. These changes in the calcium concentration in the cell interior are rapidly returned to basal levels, in the meantime, innumerable and complex signaling cascades. This note exposes the mechanisms of calcium transport through the cell membranes of the entrance of calcium in the plant cells.

  10. Calcium intake in the United States from dietary and supplemental sources across adult age groups: new estimates from the National Health and Nutrition Examination Survey 2003-2006.

    Science.gov (United States)

    Mangano, Kelsey M; Walsh, Stephen J; Insogna, Karl L; Kenny, Anne M; Kerstetter, Jane E

    2011-05-01

    Adequate lifelong calcium intake is essential in optimizing bone health. Recent National Health and Nutrition Examination Survey data were used to quantify variation in calcium intake across adult age groups and to relate age-associated changes in calcium intake with energy intake. Additional goals were to assess differences in dietary calcium intake between supplemental calcium users and nonusers and to evaluate associations between age and calcium density in the diet. This cross-sectional analysis determined calcium and energy intake for National Health and Nutrition Examination Survey respondents during 2003-2006. Diet was assessed with 24-hour recall and supplement use via questionnaire. Trends in median intakes for dietary calcium, total calcium, and energy across age categories were assessed using survey analysis methods. Nutrient density was represented using calcium to energy intake ratios. The analyses included data from 9,475 adults. When compared to the 19- to 30-year age group, median dietary calcium intake was lower in the ≥81-year age group by 23% in men (Pcalcium supplement use increased (Pcalcium intake was greater than in nonusers (P=0.02). Calcium density in the diet significantly increased relative to age in men and women (Pcalcium to energy ratios were insufficient to meet target ratios inferred by adequate intake standards after age 50 years. Although supplemental calcium use and calcium density were highest in older age groups, they were not sufficient in meeting recommended levels. New approaches to increasing the frequency and level of calcium supplement use to enhance calcium density in diets may be necessary to reduce osteoporosis risk among older Americans. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

  11. Calcium Intake in the Moroccan Elderly

    Directory of Open Access Journals (Sweden)

    Sebbar El-houcine

    2017-08-01

    Full Text Available Introduction: Calcium intakes of elderly people are often below the recommendations which are 1200 mg/day. The advancing age may be accompanied by a loss of capacity to absorb additional calcium in case of deficiency. The aim of our work is to evaluate the calcium intake in the Moroccan elderly. Methods: The version translated into Arabic dialect Fardellone questionnaire is tested on a sample of 159 subjects aged over 60 years. Results: The study population includes 87 women (55%, 72 men (45%. The mean calcium intake was respectively 3078 mg by week (that means 440 mg/day. The assessment of calcium intake showed a deficiency and the average consumption of calcium per day is significantly lower than the recommended daily amount for this population. The comparison of both gender found a deficit higher among women than among men. Conclusion: Evaluation of the calcium intake is an essential tool for better management of metabolic bone diseases.

  12. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    Calcium is one of the several elements that can be found in milk distributed between the micellar and the serum milk phase. Calcium is important from a nutritional point of view, but its contribution to the functional and structural properties of dairy products has only recently been...... acknowledgement. The presence of calcium in a dynamic equilibrium between the serum and the micellar milk phase make the distribution susceptible to certain physicochemical conditions and to technological treatments of milk resulting in fluctuations in pH and temperature and also sensitive to addition of calcium...... salts. The perturbation of calcium equilibria by these factors will affect the final properties of acid, calcium and rennet milk gels. By decreasing the pH from 6.0 to 5.2 (acid gels), the calcium equilibrium was significantly affected by temperature (4, 20, 30, 40 oC), and different combinations...

  13. Regulation of Intestinal Epithelial Calcium Transport Proteins by Stanniocalcin-1 in Caco2 Cells

    Directory of Open Access Journals (Sweden)

    Jinmei Xiang

    2016-07-01

    Full Text Available Stanniocalcin-1 (STC1 is a calcium and phosphate regulatory hormone. However, the exact molecular mechanisms underlying how STC1 affects Ca2+ uptake remain unclear. Here, the expression levels of the calcium transport proteins involved in transcellular transport in Caco2 cells were examined following over-expression or inhibition of STC1. These proteins include the transient receptor potential vanilloid members (TRPV 5 and 6, the plasma membrane calcium ATPase 1b (PMCA1b, the sodium/calcium exchanger (NCX1, and the vitamin D receptor (VDR. Both gene and protein expressions of TRPV5 and TRPV6 were attenuated in response to over-expression of STC1, and the opposite trend was observed in cells treated with siRNASTC1. To further investigate the ability of STC1 to influence TRPV6 expression, cells were treated with 100 ng/mL of recombinant human STC1 (rhSTC1 for 4 h following pre-transfection with siRNASTC1 for 48 h. Intriguingly, the increase in the expression of TRPV6 resulting from siRNASTC1 was reversed by rhSTC1. No significant effect of STC1 on the expression of PMCA1b, NCX1 or VDR was observed in this study. In conclusion, the effect of STC1 on calcium transport in intestinal epithelia is due to, at least in part, its negative regulation of the epithelial channels TRPV5/6 that mediate calcium influx.

  14. Calcium channel-dependent molecular maturation of photoreceptor synapses.

    Directory of Open Access Journals (Sweden)

    Nawal Zabouri

    Full Text Available Several studies have shown the importance of calcium channels in the development and/or maturation of synapses. The Ca(V1.4(α(1F knockout mouse is a unique model to study the role of calcium channels in photoreceptor synapse formation. It features abnormal ribbon synapses and aberrant cone morphology. We investigated the expression and targeting of several key elements of ribbon synapses and analyzed the cone morphology in the Ca(V1.4(α(1F knockout retina. Our data demonstrate that most abnormalities occur after eye opening. Indeed, scaffolding proteins such as Bassoon and RIM2 are properly targeted at first, but their expression and localization are not maintained in adulthood. This indicates that either calcium or the Ca(V1.4 channel, or both are necessary for the maintenance of their normal expression and distribution in photoreceptors. Other proteins, such as Veli3 and PSD-95, also display abnormal expression in rods prior to eye opening. Conversely, vesicle related proteins appear normal. Our data demonstrate that the Ca(V1.4 channel is important for maintaining scaffolding proteins in the ribbon synapse but less vital for proteins related to vesicular release. This study also confirms that in adult retinae, cones show developmental features such as sprouting and synaptogenesis. Overall we present evidence that in the absence of the Ca(V1.4 channel, photoreceptor synapses remain immature and are unable to stabilize.

  15. Exopolysaccharides regulate calcium flow in cariogenic biofilms.

    Science.gov (United States)

    Astasov-Frauenhoffer, Monika; Varenganayil, Muth M; Decho, Alan W; Waltimo, Tuomas; Braissant, Olivier

    2017-01-01

    Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS) provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya's agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC) by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR) spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC). Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries.

  16. Exopolysaccharides regulate calcium flow in cariogenic biofilms.

    Directory of Open Access Journals (Sweden)

    Monika Astasov-Frauenhoffer

    Full Text Available Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya's agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC. Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries.

  17. Calcium precipitate induced aerobic granulation.

    Science.gov (United States)

    Wan, Chunli; Lee, Duu-Jong; Yang, Xue; Wang, Yayi; Wang, Xingzu; Liu, Xiang

    2015-01-01

    Aerobic granulation is a novel biotechnology for wastewater treatment. This study refined existing aerobic granulation mechanisms as a sequencing process including formation of calcium precipitate under alkaline pH to form inorganic cores, followed by bacterial attachment and growth on these cores to form the exopolysaccharide matrix. Mature granules comprised an inner core and a matrix layer and a rim layer with enriched microbial strains. The inorganic core was a mix of different crystals of calcium and phosphates. Functional strains including Sphingomonas sp., Paracoccus sp. Sinorhizobium americanum strain and Flavobacterium sp. attached onto the cores. These functional strains promote c-di-GMP production and the expression by Psl and Alg genes for exopolysaccharide production to enhance formation of mature granules. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Calcium Co-regulates Oxidative Metabolism and ATP Synthase-dependent Respiration in Pancreatic Beta Cells

    Science.gov (United States)

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

    2014-01-01

    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. PMID:24554722

  19. Protein arginine deiminase 2 binds calcium in an ordered fashion: implications for inhibitor design.

    Science.gov (United States)

    Slade, Daniel J; Fang, Pengfei; Dreyton, Christina J; Zhang, Ying; Fuhrmann, Jakob; Rempel, Don; Bax, Benjamin D; Coonrod, Scott A; Lewis, Huw D; Guo, Min; Gross, Michael L; Thompson, Paul R

    2015-04-17

    Protein arginine deiminases (PADs) are calcium-dependent histone-modifying enzymes whose activity is dysregulated in inflammatory diseases and cancer. PAD2 functions as an Estrogen Receptor (ER) coactivator in breast cancer cells via the citrullination of histone tail arginine residues at ER binding sites. Although an attractive therapeutic target, the mechanisms that regulate PAD2 activity are largely unknown, especially the detailed role of how calcium facilitates enzyme activation. To gain insights into these regulatory processes, we determined the first structures of PAD2 (27 in total), and through calcium-titrations by X-ray crystallography, determined the order of binding and affinity for the six calcium ions that bind and activate this enzyme. These structures also identified several PAD2 regulatory elements, including a calcium switch that controls proper positioning of the catalytic cysteine residue, and a novel active site shielding mechanism. Additional biochemical and mass-spectrometry-based hydrogen/deuterium exchange studies support these structural findings. The identification of multiple intermediate calcium-bound structures along the PAD2 activation pathway provides critical insights that will aid the development of allosteric inhibitors targeting the PADs.

  20. Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins

    DEFF Research Database (Denmark)

    Hsu, Yu-Juei; Dimke, Henrik Anthony; Schoeber, Joost P H

    2010-01-01

    Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had...... higher urinary calcium excretion than female mice and their renal calcium transporters were expressed at a lower level. We also found that orchidectomized mice excreted less calcium in their urine than sham-operated control mice and that the hypocalciuria was normalized after testosterone replacement...... calcium transport. Thus, our study shows that gender differences in renal calcium handling are, in part, mediated by the inhibitory actions of androgens on TRPV5-mediated active renal calcium transport....

  1. A Closer look at calcium absorption and the benefits and risks of dietary versus supplemental calcium.

    Science.gov (United States)

    Booth, Anna; Camacho, Pauline

    2013-11-01

    To perform a thorough search of the literature on calcium research and specifically address the topic of calcium absorption. PubMed and Ovid were the main engines used for primary literature searches; textbooks, review articles, and book chapters are examples of the other sources used for supplemental information. Regarding calcium absorption, it seems apparent that the absorption efficiency of all calcium salts, regardless of solubility, is fairly equivalent and not significantly less than the absorption efficiency of dietary calcium. However, dietary calcium has been shown to have greater impact in bone building than supplemental calcium. This is likely due to improved absorption with meals and the tendency of people to intake smaller amounts more frequently, which is more ideal for the body's method of absorption. In addition, the cardiovascular risks of excessive calcium intake appear to be more closely related to calcium supplements than dietary calcium; this relationship continues to be controversial in the literature. We conclude that further studies are needed for direct comparison of supplemental and dietary calcium to fully establish if one is superior to the other with regard to improving bone density. We also propose further studies on the cardiovascular risk of long-term increased calcium intake and on physician estimates of patients' daily calcium intake to better pinpoint those patients who require calcium supplementation.

  2. CCN3 and calcium signaling

    Directory of Open Access Journals (Sweden)

    Li Chang Long

    2003-08-01

    Full Text Available Abstract The CCN family of genes consists presently of six members in human (CCN1-6 also known as Cyr61 (Cystein rich 61, CTGF (Connective Tissue Growth Factor, NOV (Nephroblastoma Overexpressed gene, WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins. Results obtained over the past decade have indicated that CCN proteins are matricellular proteins, which are involved in the regulation of various cellular functions, such as proliferation, differentiation, survival, adhesion and migration. The CCN proteins have recently emerged as regulatory factors involved in both internal and external cell signaling. CCN3 was reported to physically interact with fibulin-1C, integrins, Notch and S100A4. Considering that, the conformation and biological activity of these proteins are dependent upon calcium binding, we hypothesized that CCN3 might be involved in signaling pathways mediated by calcium ions. In this article, we review the data showing that CCN3 regulates the levels of intracellular calcium and discuss potential models that may account for the biological effects of CCN3.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuerun, E-mail: xuerunli@163.com; Zhang, Yu; Shen, Xiaodong, E-mail: xdshen@njut.edu.cn; 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.

  4. Presenilin-mediated modulation of capacitative calcium entry.

    Science.gov (United States)

    Yoo, A S; Cheng, I; Chung, S; Grenfell, T Z; Lee, H; Pack-Chung, E; Handler, M; Shen, J; Xia, W; Tesco, G; Saunders, A J; Ding, K; Frosch, M P; Tanzi, R E; Kim, T W

    2000-09-01

    We studied a novel function of the presenilins (PS1 and PS2) in governing capacitative calcium entry (CCE), a refilling mechanism for depleted intracellular calcium stores. Abrogation of functional PS1, by either knocking out PS1 or expressing inactive PS1, markedly potentiated CCE, suggesting a role for PS1 in the modulation of CCE. In contrast, familial Alzheimer's disease (FAD)-linked mutant PS1 or PS2 significantly attenuated CCE and store depletion-activated currents. While inhibition of CCE selectively increased the amyloidogenic amyloid beta peptide (Abeta42), increased accumulation of the peptide had no effect on CCE. Thus, reduced CCE is most likely an early cellular event leading to increased Abeta42 generation associated with FAD mutant presenilins. Our data indicate that the CCE pathway is a novel therapeutic target for Alzheimer's disease.

  5. Increased Calcium Supplementation Postpartum Is Associated with Breastfeeding among Chinese Mothers: Finding from Two Prospective Cohort Studies.

    Science.gov (United States)

    Zhao, Jian; Zhao, Yun; Binns, Colin W; Lee, Andy H

    2016-10-09

    The calcium supplementation status during the postpartum period among Chinese lactating women is still unclear. The objective of this study is to utilize data from two population-based prospective cohort studies to examine the calcium supplementation status and to identify whether breastfeeding is associated with increased calcium supplementation among Chinese mothers after child birth. Information from 1540 mothers on breastfeeding and calcium supplementation measured at discharge, 1, 3, and 6 months postpartum were extracted to evaluate the association between breastfeeding and calcium supplementation postpartum. A generalized linear mixed model was applied to each study initially to account for the inherent correlation among repeated measurements, adjusting for socio-demographic, obstetric factors and calcium supplementation during pregnancy. In addition, breastfeeding status measured at different follow-up time points was treated as a time dependent variable in the longitudinal analysis. Furthermore, the effect sizes of the two cohort studies were pooled using fixed effect model. Based on the two cohort studies, the pooled likelihood of taking calcium supplementation postpartum among breastfeeding mothers was 4.02 times (95% confidence interval (2.30, 7.03)) higher than that of their non-breastfeeding counterparts. Dietary supplementation intervention programs targeting different subgroups should be promoted in Chinese women, given currently a wide shortage of dietary calcium intake and calcium supplementation postpartum.

  6. Dual effect of magnesium on compound 48/80-induced histamine secretion from rat peritoneal mast cells

    DEFF Research Database (Denmark)

    Bertelsen, Niels Haldor; Johansen, Torben

    1991-01-01

    The effect of magnesium on the secretory response to compound 48/80 from rat peritoneal mast cells was studied. The decrease in secretion caused by calcium deprivation was enlarged by magnesium. Glucose partially counteracted the decrease caused by calcium deprivation but not the one caused...... by magnesium. The addition of calcium to the cells simultaneously with compound 48/80 completely restored the secretory response if magnesium was present. The response was only partially restored in a magnesium- and glucose-free medium, whereas it was almost completely restored if glucose was present....... Magnesium had a considerable effect on the restoration of the secretory response of EGTA-treated cells, whereas the effect of glucose was minimal indicating that an effect on the energy metabolism was of minor importance. The secretory response could also be restored by an exposure of the cells to calcium...

  7. Cross-talk between ROS and calcium in regulation of nuclear activities.

    Science.gov (United States)

    Mazars, Christian; Thuleau, Patrice; Lamotte, Olivier; Bourque, Stéphane

    2010-07-01

    Calcium and Reactive Oxygen Species (ROS) are acknowledged as crucial second messengers involved in the response to various biotic and abiotic stresses. However, it is still not clear how these two compounds can play a role in different signaling pathways leading the plant to a variety of processes such as root development or defense against pathogens. Recently, it has been shown that the concept of calcium and ROS signatures, initially discovered in the cytoplasm, can also be extended to the nucleus of plant cells. In addition, it has been clearly proved that both ROS and calcium signals are intimately interconnected. How this cross-talk can finally modulate the translocation and/or the activity of nuclear proteins leading to the control of specific genes expression is the main focus of this review. We will especially focus on how calcium and ROS interact at the molecular level to modify their targets.

  8. The Role of Calcium in Osteoporosis

    Science.gov (United States)

    Arnaud, C. D.; Sanchez, S. D.

    1991-01-01

    Calcium requirements may vary throughout the lifespan. During the growth years and up to age 25 to 30, it is important to maximize dietary intake of calcium to maintain positive calcium balance and achieve peak bone mass, thereby possibly decreasing the risk of fracture when bone is subsequently lost. Calcium intake need not be greater than 800 mg/day during the relatively short period of time between the end of bone building and the onset of bone loss (30 to 40 years). Starting at age 40 to 50, both men and women lose bone slowly, but women lose bone more rapidly around the menopause and for about 10 years after. Intestinal calcium absorption and the ability to adapt to low calcium diets are impaired in many postmenopausal women and elderly persons owing to a suspected functional or absolute decrease in the ability of the kidney to produce 1,25(OH)2D2. The bones then become more and more a source of calcium to maintain critical extracellular fluid calcium levels. Excessive dietary intake of protein and fiber may induce significant negative calcium balance and thus increase dietary calcium requirements. Generally, the strongest risk factors for osteoporosis are uncontrollable (e.g., sex, age, and race) or less controllable (e.g., disease and medications). However, several factors such as diet, physical activity, cigarette smoking, and alcohol use are lifestyle related and can be modified to help reduce the risk of osteoporosis.

  9. Assessment of calcium intake by adolescents

    Directory of Open Access Journals (Sweden)

    Cristiane Franco de Oliveira

    2014-06-01

    Full Text Available OBJECTIVE: To evaluate the daily calcium intake of adolescents in schools from Chapecó, Santa Catarina, Southern Brazil, to check if calcium intake is in accordance with the Dietary Reference Intakes (DRI, and to investigate variables associated with daily calcium intake.METHODS: Cross-sectional study approved by the Institutional Review Board and developed in 2010. Students of the 8th grade completed questionnaires with personal data and questions about the calcium-rich foods intake frequency. In order to compare students with adequate (1300mg or inadequate intake of calcium/day (<1300mg, parametric and nonparametric tests were used.RESULTS: A total of 214 students with a mean age of 14.3±1.0 years were enrolled. The median daily calcium intake was 540mg (interquartile range - IQ: 312-829mg and only 25 students (11.7% had calcium intake within the recommendations of the DRI for age. Soft drink consumption ≥3 times/week was associated with a lower intake of calcium.CONCLUSIONS: Few students ingested adequate levels of calcium for the age group. It is necessary to develop a program to encourage a greater intake of calcium-rich foods in adolescence.

  10. The Risks and Benefits of Calcium Supplementation

    Directory of Open Access Journals (Sweden)

    Chan Soo Shin

    2015-03-01

    Full Text Available The association between calcium supplementation and adverse cardiovascular events has recently become a topic of debate due to the publication of two epidemiological studies and one meta-analysis of randomized controlled clinical trials. The reports indicate that there is a significant increase in adverse cardiovascular events following supplementation with calcium; however, a number of experts have raised several issues with these reports such as inconsistencies in attempts to reproduce the findings in other populations and questions concerning the validity of the data due to low compliance, biases in case ascertainment, and/or a lack of adjustment. Additionally, the Auckland Calcium Study, the Women's Health Initiative, and many other studies included in the meta-analysis obtained data from calcium-replete subjects and it is not clear whether the same risk profile would be observed in populations with low calcium intakes. Dietary calcium intake varies widely throughout the world and it is especially low in East Asia, although the risk of cardiovascular events is less prominent in this region. Therefore, clarification is necessary regarding the occurrence of adverse cardiovascular events following calcium supplementation and whether this relationship can be generalized to populations with low calcium intakes. Additionally, the skeletal benefits from calcium supplementation are greater in subjects with low calcium intakes and, therefore, the risk-benefit ratio of calcium supplementation is likely to differ based on the dietary calcium intake and risks of osteoporosis and cardiovascular diseases of various populations. Further studies investigating the risk-benefit profiles of calcium supplementation in various populations are required to develop population-specific guidelines for individuals of different genders, ages, ethnicities, and risk profiles around the world.

  11. Shear stress induction of the endothelial nitric oxide synthase gene is calcium-dependent but not calcium-activated.

    Science.gov (United States)

    Xiao, Z; Zhang, Z; Ranjan, V; Diamond, S L

    1997-05-01

    Arterial levels of shear stress (25 dynes/cm2) can elevate constitutive endothelial nitric oxide synthase (eNOS) gene expression in cultured endothelial cells (Ranjan et al., 1995). By PhosphorImaging of Northern blots, we report that the eNOS/glyceraldehyde 3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA) ratio in bovine aortic endothelial cells (BAEC) increased by 4.8- and 7.95-fold after 6-hr shear stress exposure of 4 and 25 dynes/cm2, respectively. Incubation of BAEC with dexamethasone (1 microM) had no effect on shear stress induction of eNOS mRNA. Buffering of intracellular calcium in BAEC with bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester (BAPTA/AM) reduced shear stress induction of eNOS mRNA by 70%. Yet, stimulation of BAEC with ionomycin (0.1-1.0 microM) for 6-24 hr to elevate intracellular calcium had no effect on eNOS mRNA. These studies indicated that the shear stress induction of eNOS mRNA was a calcium-dependent, but not calcium-activated, process. Shear stress was a very potent and rapid inducer of the eNOS mRNA, which could not be mimicked with phorbol myristrate acetate or endotoxin. Inhibition of tyrosine kinases with genistein (10 microM) or tyrphostin B46 (10 microM) or inhibition of G-protein signaling with guanosine 5'-O-(2-thiodiphosphate) (GDP-betaS) (600 microM, 6-hr preincubation) did not block the shear stress elevation of eNOS mRNA.

  12. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    OpenAIRE

    Eder, Anja; Bading, Hilmar

    2007-01-01

    Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nuc...

  13. Antiproton Target

    CERN Multimedia

    1980-01-01

    Antiproton target used for the AA (antiproton accumulator). The first type of antiproton production target used from 1980 to 1982 comprised a rod of copper 3mm diameter and 120mm long embedded in a graphite cylinder that was itself pressed into a finned aluminium container. This assembly was air-cooled and it was used in conjunction with the Van der Meer magnetic horn. In 1983 Fermilab provided us with lithium lenses to replace the horn with a view to increasing the antiproton yield by about 30%. These lenses needed a much shorter target made of heavy metal - iridium was chosen for this purpose. The 50 mm iridium rod was housed in an extension to the original finned target container so that it could be brought very close to the entrance to the lithium lens. Picture 1 shows this target assembly and Picture 2 shows it mounted together with the lithium lens. These target containers had a short lifetime due to a combination of beam heating and radiation damage. This led to the design of the water-cooled target in...

  14. Calcium gluconate supplementation is effective to balance calcium homeostasis in patients with gastrectomy.

    Science.gov (United States)

    Krause, M; Keller, J; Beil, B; van Driel, I; Zustin, J; Barvencik, F; Schinke, T; Amling, M

    2015-03-01

    We demonstrate histological evidence for hyperparathyroidism in patients with gastrectomy. This is, at least in part, explained by impaired calcium absorption, resulting in mineralization defects and secondary hyperparathyroidism. Additionally, we demonstrate improved bone mineralization in patients with gastrectomy after gluconate therapy and showed the effectiveness of calcium gluconate over carbonate to balance impaired calcium hemostasis in mice. Gastrectomy and hypochlorhydria due to long-term proton pump inhibitor therapy are associated with increased fracture risk because of intestinal calcium malabsorption. Hence, our objectives were to histologically investigate bone metabolism in patients with gastrectomy and to analyze the impact of calcium gluconate supplementation on skeletal integrity in the setting of impaired gastric acidification. Undecalcified bone biopsies of 26 gastrectomized individuals were histologically analyzed. In the clinical setting, we retrospectively identified 5 gastrectomized patients with sufficient vitamin D level, who were additionally supplemented with calcium gluconate and had a real bone mineral density (aBMD) follow-up assessments. A mouse model of achlorhydria (ATP4b-/-) was used to compare the effect of calcium gluconate and calcium carbonate supplementation on bone metabolism. Biopsies from gastrectomized individuals showed significantly increased osteoid, osteoclast, and osteoblast indices and fibroosteoclasia (p < 0.05) as well as impaired calcium distribution in mineralized bone matrix compared to healthy controls. Five gastrectomized patients with sufficient vitamin D level demonstrated a significant increase in aBMD after a treatment with calcium gluconate alone for at least 6 months (p < 0.05). Calcium gluconate was superior to calcium carbonate in maintaining calcium metabolism in a mouse model of achlorhydria. Gastrectomy is associated with severe osteomalacia, marrow fibrosis, and impaired calcium distribution

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

    Science.gov (United States)

    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.

  16. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    Directory of Open Access Journals (Sweden)

    Bading Hilmar

    2007-07-01

    Full Text Available Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.

  17. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    Science.gov (United States)

    Eder, Anja; Bading, Hilmar

    2007-01-01

    Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events. PMID:17663775

  18. Prediction of the Chloride Resistance of Concrete Modified with High Calcium Fly Ash Using Machine Learning.

    Science.gov (United States)

    Marks, Michał; Glinicki, Michał A; Gibas, Karolina

    2015-12-11

    The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions' penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing the relation between material composition and the chloride resistance. Multiple methods for rule generation were applied and compared. The rules generated by algorithm J48 from the Weka workbench provided the means for adequate classification of plain concretes and concretes modified with high calcium fly ash as materials of good, acceptable or unacceptable resistance to chloride penetration.

  19. Dietary intake of calcium, vitamins A and E and bleeding on probing in Sri Lankan preschoolers.

    Science.gov (United States)

    Nanayakkara, V; Ekanayake, L; Silva, R

    2014-09-01

    To determine the prevalence of gingival bleeding on probing and the associations between dietary intake of calcium, vitamins A and E and gingival bleeding on probing in Sri Lankan preschool children. A cross-sectional study. 784 children aged 48-72 months attending preschools in the Kegalle district and their mothers/carers. The prevalence of gingival bleeding on probing was 52.9%. A Poisson logistic regression model revealed that children with a high daily dietary intake of calcium were less likely to have gingival bleeding on probing than those with low intake (PR=0.80; 95%CI 0.64,0.98). Also prevalence of gingival bleeding was higher in children: with plaque on their teeth; whose mothers were not employed; or, were from families with three or more children. The prevalence of gingivitis was high in the children and the findings suggest that high levels of dietary calcium intake are associated with reduced gingival bleeding in preschool children.

  20. Astrocytic Calcium Waves Signal Brain Injury to Neural Stem and Progenitor Cells

    Directory of Open Access Journals (Sweden)

    Anna Kraft

    2017-03-01

    Full Text Available Brain injuries, such as stroke or trauma, induce neural stem cells in the subventricular zone (SVZ to a neurogenic response. Very little is known about the molecular cues that signal tissue damage, even over large distances, to the SVZ. Based on our analysis of gene expression patterns in the SVZ, 48 hr after an ischemic lesion caused by middle cerebral artery occlusion, we hypothesized that the presence of an injury might be transmitted by an astrocytic traveling calcium wave rather than by diffusible factors or hypoxia. Using a newly established in vitro system we show that calcium waves induced in an astrocytic monolayer spread to neural stem and progenitor cells and increase their self-renewal as well as migratory behavior. These changes are due to an upregulation of the Notch signaling pathway. This introduces the concept of propagating astrocytic calcium waves transmitting brain injury signals over long distances.

  1. Induced calcium carbonate precipitation using Bacillus species.

    Science.gov (United States)

    Seifan, Mostafa; Samani, Ali Khajeh; Berenjian, Aydin

    2016-12-01

    Microbially induced calcium carbonate precipitation is an emerging process for the production of self-healing concrete. This study was aimed to investigate the effects and optimum conditions on calcium carbonate biosynthesis. Bacillus licheniformis, Bacillus sphaericus, yeast extract, urea, calcium chloride and aeration were found to be the most significant factors affecting the biomineralization of calcium carbonate. It was noticed that the morphology of microbial calcium carbonate was mainly affected by the genera of bacteria (cell surface properties), the viscosity of the media and the type of electron acceptors (Ca2+). The maximum calcium carbonate concentration of 33.78 g/L was achieved at the optimum conditions This value is the highest concentration reported in the literature.

  2. Calcium excretion in feces of ungulates.

    Science.gov (United States)

    Schryver, H F; Foose, T J; Williams, J; Hintz, H F

    1983-01-01

    1. Fecal excretion of calcium was examined in 122 individual ungulates representing 7 species of Equidae, 3 species of Tapiridae, 3 species of Rhinocerotidae, 2 species of Elephantidae, 2 species of Hippopotamidae, 12 species of Bovidae, 2 species of Cervidae, 3 species of Camellidae and 1 species of Giraffidae. 2. Animals were fed timothy hay, a low calcium diet or alfalfa hay, a high calcium diet. 3. In a few cases oat straw or prairie hay was used instead of timothy hay. 4. Samples of feces were obtained from individuals daily for 4 days following a 20 day dietary equilibration period. 5. Feces of equids, tapirs, rhinoceros and elephants had a lower calcium concentration and a lower Ca/P ratio than feces of ruminants when the animals were fed diets of equivalent calcium content. 6. The findings suggest that the non-ruminant ungulate equids, tapirs, rhinoceros and elephants absorb a larger proportion of dietary calcium than ruminants do.

  3. Binding of calcium and carbonate to polyacrylates.

    Science.gov (United States)

    Tribello, Gareth A; Liew, CheeChin; Parrinello, Michele

    2009-05-21

    Polyacrylate molecules can be used to slow the growth of calcium carbonate. However, little is known about the mechanism by which the molecules impede the growth rate. A recent computational study (Bulo et al. Macromolecules 2007, 40, 3437) used metadynamics to investigate the binding of calcium to polyacrylate chains and has thrown some light on the coiling and precipitation of these polymers. We extend these simulations to examine the binding of calcium and carbonate to polyacrylate chains. We show that calcium complexed with both carbonate and polyacrylate is a very stable species. The free energies of calcium-carbonate-polyacrylate complexes, with different polymer configurations, are calculated, and differences in the free energy of the binding of carbonate are shown to be due to differences in the amount of steric hindrance about the calcium, which prevents the approach of the carbonate ion.

  4. WAYS TO CORRECT CALCIUM DEFFICIT AMONG CHILDREN

    Directory of Open Access Journals (Sweden)

    N.I. Taibulatov

    2007-01-01

    Full Text Available The article is dedicated to the urgent issue of the pediatrics — calcium deficit among children. The authors provide modern data on the scheme of the normal calcium exchange in the human body. They also review the main diseases related to the disorders of the pho sphorocalcic metabolism, requiring prompt prevention and treatment by calcium based medications. The researchers stress the diseases of the musculoskeletal system, as insufficient calcium, phosphorus and vitamins supply of the child's body chiefly effects the state of the skeletal and muscular tissue. They give recommendations how to use the vitamin and mineral complex to correct calcium deficit.Key words: calcium deficit, diseases of the musculoskeletal system, vitamin and mineral complex, children.

  5. Calcium dobesilate: pharmacology and future approaches.

    Science.gov (United States)

    Tejerina, T; Ruiz, E

    1998-09-01

    1. Calcium dobesilate (2,5-dihydroxybenzene sulfonate) is a drug commonly used in the treatment of diabetic retinopathy and chronic venous insufficiency. 2. The pharmacology of calcium dobesilate reveals its ability to decrease capillary permeability, as well as platelet aggregation and blood viscosity. 3. Furthermore, recent data show that calcium dobesilate increases endothelium-dependent relaxation owing to an increase in nitric oxide synthesis.

  6. Presynaptic calcium dynamics of learning neurons

    OpenAIRE

    Meyer-Hermann, Michael; Erler, Frido; Soff, Gerhard

    2002-01-01

    We present a new model for the dynamics of the presynaptic intracellular calcium concentration in neurons evoked by various stimulation protocols. The aim of the model is twofold: We want to discuss the calcium transients during and after specific stimulation protocols as they are used to induce long-term-depression and long-term-potentiation. In addition we would like to provide a general tool which allows the comparison of different calcium experiments. This may help to draw conclusions on ...

  7. Protein-Mediated Precipitation of Calcium Carbonate

    OpenAIRE

    Izabela Polowczyk; Anna Bastrzyk; Marta Fiedot

    2016-01-01

    Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquire...

  8. Mechanical Properties of a Calcium Dietary Supplement, Calcium Fumarate Trihydrate.

    Science.gov (United States)

    Sun, Shijing; Henke, Sebastian; Wharmby, Michael T; Yeung, Hamish H-M; Li, Wei; Cheetham, Anthony K

    2015-12-07

    The mechanical properties of calcium fumarate trihydrate, a 1D coordination polymer considered for use as a calcium source for food and beverage enrichment, have been determined via nanoindentation and high-pressure X-ray diffraction with single crystals. The nanoindentation studies reveal that the elastic modulus (16.7-33.4 GPa, depending on crystallographic orientation), hardness (1.05-1.36 GPa), yield stress (0.70-0.90 GPa), and creep behavior (0.8-5.8 nm/s) can be rationalized in view of the anisotropic crystal structure; factors include the directionality of the inorganic Ca-O-Ca chain and hydrogen bonding, as well as the orientation of the fumarate ligands. High-pressure single-crystal X-ray diffraction studies show a bulk modulus of ∼ 20 GPa, which is indicative of elastic recovery intermediate between small molecule drug crystals and inorganic pharmaceutical ingredients. The combined use of nanoindentation and high-pressure X-ray diffraction techniques provides a complementary experimental approach for probing the critical mechanical properties related to tableting of these dietary supplements.

  9. Calcium dependence of inactivation of calcium release from the sarcoplasmic reticulum in skeletal muscle fibers.

    Science.gov (United States)

    Simon, B J; Klein, M G; Schneider, M F

    1991-03-01

    The steady-state calcium dependence of inactivation of calcium release from the sarcoplasmic reticulum was studied in voltage-clamped, cut segments of frog skeletal muscle fibers containing two calcium indicators, fura-2 and anti-pyrylazo III (AP III). Fura-2 fluorescence was used to monitor resting calcium and relatively small calcium transients during small depolarizations. AP III absorbance signals were used to monitor larger calcium transients during larger depolarizations. The rate of release (Rrel) of calcium from the sarcoplasmic reticulum was calculated from the calcium transients. The equilibrium calcium dependence of inactivation of calcium release was determined using 200-ms prepulses of various amplitudes to elevate [Ca2+] to various steady levels. Each prepulse was followed by a constant test pulse. The suppression of peak Rrel during the test pulse provided a measure of the extent of inactivation of release at the end of the prepulse. The [Ca2+] dependence of inactivation indicated that binding of more than one calcium ion was required to inactivate each release channel. Half-maximal inactivation was produced at a [Ca2+] of approximately 0.3 microM. Variation of the prepulse duration and amplitude showed that the suppression of peak release was consistent with calcium-dependent inactivation of calcium release but not with calcium depletion. The same calcium dependence of inactivation was obtained using different amplitude test pulses to determine the degree of inactivation. Prepulses that produced near maximal inactivation of release during the following test pulse produced no suppression of intramembrane charge movement during the test pulse, indicating that inactivation occurred at a step beyond the voltage sensor for calcium release. Three alternative set of properties that were assumed for the rapidly equilibrating calcium-binding sites intrinsic to the fibers gave somewhat different Rrel records, but gave very similar calcium dependence of

  10. Protein-Mediated Precipitation of Calcium Carbonate.

    Science.gov (United States)

    Polowczyk, Izabela; Bastrzyk, Anna; Fiedot, Marta

    2016-11-22

    Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure's growth in the investigated system. In this study, samples of CaCO₃ particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to 'stack-like' structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO₃ formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein.

  11. Diuretics and disorders of calcium homeostasis.

    Science.gov (United States)

    Grieff, Marvin; Bushinsky, David A

    2011-11-01

    Diuretics commonly are administered in disorders of sodium balance. Loop diuretics inhibit the Na-K-2Cl transporter and also increase calcium excretion. They are often used in the treatment of hypercalcemia. Thiazide diuretics block the thiazide-sensitive NaCl transporter in the distal convoluted tubule, and can decrease calcium excretion. They are often used in the treatment of nephrolithiasis. Carbonic anhydrase inhibitors decrease bicarbonate absorption and the resultant metabolic acidosis can increase calcium excretion. Their use can promote nephrocalcinosis and nephrolithiasis. This review will address the use of diuretics on disorders of calcium homeostasis. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. [ZINK IS ACTIVATOR OF ENTERAL CALCIUM METABOLISM].

    Science.gov (United States)

    Polyakova, E P; Ksenofontov, D A; Revyakin, A O; Ivanov, A A

    2015-01-01

    Experiments on goats and rabbits showed that zinc supplement to the diet leads to calcium concentration rise in muscle, bone and blood of animals. However, this rise was not adequate to increase in.zinc consumption. The bulk of alimentary zinc stayed in soluble fraction, dense endogen fraction and infusoria fraction of digesta and stimulated calcium release from food particles, it's accumulation in digesta fractions and calcium utilization on the whole. Authors estimate animal digesta as homeostatic, spatial organized, endogenic formation in which zinc and calcium are functionally dependent through enteral mucosa.

  13. The Electronic Structure of Calcium

    DEFF Research Database (Denmark)

    Jan, J.-P.; Skriver, Hans Lomholt

    1981-01-01

    .149 Ryd, respectively, relative to the s band, give the best possible agreement. Under increasing pressure the s and p electrons are found to transfer into the d band, and Ca undergoes metal-semimetal-metal electronic transitions. Calculations of the bandstructure and the electronic pressure, including......The electronic structure of calcium under pressure is re-examined by means of self-consistent energy band calculations based on the local density approximation and using the linear muffin-tin orbitals (LMTO) method with corrections to the atomic sphere approximation included. At zero pressure...

  14. Distinct Calcium Sources Support Multiple Modes of Synaptic Release from Cranial Sensory Afferents.

    Science.gov (United States)

    Fawley, Jessica A; Hofmann, Mackenzie E; Andresen, Michael C

    2016-08-24

    sources: CaVs and TRPV1. We demonstrate that calcium segregation distinguishes three vesicle release mechanisms. Most surprisingly, asynchronous release is associated with CaV and not TRPV1 calcium entry. This reveals that asynchronous release is an additional and separate phenotypic marker of unmyelinated afferents rather than operated by TRPV1. The functional independence of the two calcium sources expands the regulatory repertoire of transmission and imbues these inputs with additional modulation targets for synaptic release not present at conventional CaV synapses. Peptides and lipid mediators may target one or both of these calcium sources at afferent terminals within the solitary tract nucleus to independently modify release from distinct, functionally segregated vesicle pools. Copyright © 2016 the authors 0270-6474/16/368957-10$15.00/0.

  15. Short communication: Urinary oxalate and calcium excretion by dogs and cats diagnosed with calcium oxalate urolithiasis

    NARCIS (Netherlands)

    Dijcker, J.C.; Kummeling, A.; Hagen-Plantinga, E.A.; Hendriks, W.H.

    2012-01-01

    Introduction Urine concentrations of oxalate and calcium play an important role in calcium oxalate (CaOx) urolith formation in dogs and cats, with high excretions of both substances increasing the chance of CaOx urolithiasis. In 17 CaOx-forming dogs, urine calcium:creatinine ratio (Ca:Cr) was found

  16. Impaired body calcium metabolism with low bone density and compensatory colonic calcium absorption in cecectomized rats

    NARCIS (Netherlands)

    Jongwattanapisan, P.; Suntornsaratoon, P.; Wongdee, K.; Dorkkam, N.; Krishnamra, N.; Charoenphandhu, N.

    2012-01-01

    An earlier study reported that cecal calcium absorption contributes less than 10% of total calcium absorbed by the intestine, although the cecum has the highest calcium transport rate compared with other intestinal segments. Thus, the physiological significance of the cecum pertaining to body

  17. Pharmacological modulation of mitochondrial calcium homeostasis.

    Science.gov (United States)

    Arduino, Daniela M; Perocchi, Fabiana

    2018-01-10

    Mitochondria are pivotal organelles in calcium (Ca2+ ) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca2+ homeostasis have been linked to a variety of pathological conditions and are critical in the etiology of several human diseases. Efforts have been taken to harness mitochondrial Ca2+ transport mechanisms for therapeutic intervention but pharmacological compounds that direct and selectively modulate mitochondrial Ca2+ homeostasis are currently lacking. New avenues have however emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progresses towards a systems-level pharmacological targeting of mitochondrial Ca2+ homeostasis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  18. Plasma membrane calcium pump and sodium-calcium exchanger in maintenance and control of calcium concentrations in platelets.

    Science.gov (United States)

    Juska, Alfonsas

    2010-01-29

    The purpose of this research was to elucidate the activity of the mechanisms responsible for control of cytosolic calcium concentration in platelets by modeling the time-course of the concentration changing in response to discharge of the intracellular stores or store-operated calcium entry (SOCE). The parameters estimated as a result of model fitting to experimental data are related to physiological or pathological state of the cells. It has been shown that: (a) the time-course is determined by the passive calcium fluxes and activities of the corresponding mechanisms; (b) the decline in the concentration (after its rise) develops due to activity of plasma membrane calcium ATPase (PMCA) both in the case of discharge of the stores of platelets contained in calcium-free medium and in the case of SOCE; (c) impulsive extrusion of calcium in response to its sudden influx, presumably, is the main function of PMCA; (d) the function of sodium-calcium exchanger (NCX) is to extrude calcium excess by permanent counteracting its influx. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  19. The effects of a calcium-rich pre-exercise meal on biomarkers of calcium homeostasis in competitive female cyclists: a randomised crossover trial.

    Directory of Open Access Journals (Sweden)

    Eric C Haakonssen

    Full Text Available To examine whether a calcium-rich pre-exercise meal attenuates exercise-induced perturbations of bone calcium homeostasis caused by maintenance of sweat calcium losses.Using a randomized, counterbalanced crossover design, 32 well-trained female cyclists completed two 90 min cycling trials separated by 1 day. Exercise trials were preceded 2 hours by either a calcium-rich (1352 ± 53 mg calcium dairy based meal (CAL or a control meal (CON; 46 ± 7 mg calcium. Blood was sampled pre-trial; pre-exercise; and immediately, 40 min, 100 min and 190 min post-exercise. Blood was analysed for ionized calcium and biomarkers of bone resorption (Cross Linked C-Telopeptide of Type I Collagen (CTX-I, Cross Linked C-Telopeptide of Type II Collagen (CTX-II, Parathyroid Hormone (PTH, and bone formation (Procollagen I N-Terminal Propeptide (PINP using the established enzyme-linked immunosorbent assay technique.PTH and CTX-I increased from pre-exercise to post-exercise in both conditions but was attenuated in CAL (p < 0.001. PTH was 1.55 [1.20, 2.01] times lower in CAL immediately post-exercise and 1.45 [1.12, 1.88] times lower at 40 min post-exercise. CTX-I was 1.40 [1.15, 1.70] times lower in CAL at immediately post-exercise, 1.30 [1.07, 1.57] times lower at 40 min post-exercise and 1.22 [1.00, 1.48] times lower at 190 min post-exercise (p < 0.05. There was no significant interaction between pre-exercise meal condition and time point for CTX-II (p = 0.732 or PINP (p = 0.819.This study showed that a calcium-rich pre-exercise breakfast meal containing ~1350 mg of calcium consumed ~90 min before a prolonged and high intensity bout of stationary cycling attenuates the exercise induced rise in markers of bone resorption--PTH and CTX-I.Australian New Zealand Clinical Trials Registry ACTRN12614000675628.

  20. Calcium dobesilate in the treatment of diabetic retinopathy.

    Science.gov (United States)

    Garay, Ricardo P; Hannaert, Patrick; Chiavaroli, Carlo

    2005-01-01

    The incidence of diabetic retinopathy is still increasing in developed countries. Tight glycemic control and laser therapy reduce vision loss and blindness, but do not reverse existing ocular damage and only slow the progression of the disease. New pharmacologic agents that are currently under development and are specifically directed against clearly defined biochemical targets (i.e. aldose reductase inhibitors and protein kinase C-beta inhibitors) have failed to demonstrate significant efficacy in the treatment of diabetic retinopathy in clinical trials. In contrast, calcium dobesilate (2,5-dihydroxybenzenesulfonate), which was discovered more than 40 years ago and is registered for the treatment of diabetic retinopathy in more than 20 countries remains, to our knowledge, the only angioprotective agent that reduces the progression of this disease. An overall review of published studies involving calcium dobesilate (CLS 2210) depicts a rather 'non-specific' compound acting moderately, but significantly, on the various and complex disorders that contribute to diabetic retinopathy. Recent studies have shown that calcium dobesilate is a potent antioxidant, particularly against the highly damaging hydroxyl radical. In addition, it improves diabetic endothelial dysfunction, reduces apoptosis, and slows vascular cell proliferation.

  1. A basic study on the production of enriched isotope {}^{48}Ca by using crown-ether resin

    Science.gov (United States)

    Umehara, S.; Kishimoto, T.; Kakubata, H.; Nomura, M.; Kaneshiki, T.; Suzuki, T.; Fujii, Y.; Nemoto, S.

    2015-05-01

    The use of enriched ^{48}Ca is expected to improve the sensitivity of ^{48}Ca double beta decay measurements. We have studied the enrichment of ^{48}Ca with chemical exchange isotope separation using benzo-18-crown-6-ether resin. Chromatographic migrations of the calcium adsorption band were carried out at different migration lengths, 1 m, 20 m, and 200 m, using glass columns. Separation coefficients were observed as approximately 3 × 10^{-3}. Efforts have been made towards the production of benzo-18-crown-6-ether monomer at reasonable cost for the production of crown-ether resin for the separation of ^{48}Ca.

  2. Spatiotemporal intracellular calcium dynamics during cardiac alternans

    Science.gov (United States)

    Restrepo, Juan G.; Karma, Alain

    2009-09-01

    Cellular calcium transient alternans are beat-to-beat alternations in the peak cytosolic calcium concentration exhibited by cardiac cells during rapid electrical stimulation or under pathological conditions. Calcium transient alternans promote action potential duration alternans, which have been linked to the onset of life-threatening ventricular arrhythmias. Here we use a recently developed physiologically detailed mathematical model of ventricular myocytes to investigate both stochastic and deterministic aspects of intracellular calcium dynamics during alternans. The model combines a spatially distributed description of intracellular calcium cycling, where a large number of calcium release units are spatially distributed throughout the cell, with a full set of ionic membrane currents. The results demonstrate that ion channel stochasticity at the level of single calcium release units can influence the whole-cell alternans dynamics by causing phase reversals over many beats during fixed frequency pacing close to the alternans bifurcation. They also demonstrate the existence of a wide range of dynamical states. Depending on the sign and magnitude of calcium-voltage coupling, calcium alternans can be spatially synchronized or desynchronized, in or out of phase with action potential duration alternans, and the node separating out-of-phase regions of calcium alternans can be expelled from or trapped inside the cell. This range of states is found to be larger than previously anticipated by including a robust global attractor where calcium alternans can be spatially synchronized but out of phase with action potential duration alternans. The results are explained by a combined theoretical analysis of alternans stability and node motion using general iterative maps of the beat-to-beat dynamics and amplitude equations.

  3. When Neurons Encounter Nanoobjects: Spotlight on Calcium Signalling

    Directory of Open Access Journals (Sweden)

    Davide Lovisolo

    2014-09-01

    Full Text Available Nanosized objects are increasingly present in everyday life and in specialized technological applications. In recent years, as a consequence of concern about their potential adverse effects, intense research effort has led to a better understanding of the physicochemical properties that underlie their biocompatibility or potential toxicity, setting the basis for a rational approach to their use in the different fields of application. Among the functional parameters that can be perturbed by interaction between nanoparticles (NPs and living structures, calcium homeostasis is one of the key players and has been actively investigated. One of the most relevant biological targets is represented by the nervous system (NS, since it has been shown that these objects can access the NS through several pathways; moreover, engineered nanoparticles are increasingly developed to be used for imaging and drug delivery in the NS. In neurons, calcium homeostasis is tightly regulated through a complex set of mechanisms controlling both calcium increases and recovery to the basal levels, and even minor perturbations can have severe consequences on neuronal viability and function, such as excitability and synaptic transmission. In this review, we will focus on the available knowledge about the effects of NPs on the mechanisms controlling calcium signalling and homeostasis in neurons. We have taken into account the data related to environmental NPs, and, in more detail, studies employing engineered NPs, since their more strictly controlled chemical and physical properties allow a better understanding of the relevant parameters that determine the biological responses they elicit. The literature on this specific subject is all quite recent, and we have based the review on the data present in papers dealing strictly with nanoparticles and calcium signals in neuronal cells; while they presently amount to about 20 papers, and no related review is available, the field is

  4. Coronary artery calcium scoring: Influence of adaptive statistical iterative reconstruction using 64-MDCT.

    Science.gov (United States)

    Gebhard, Cathérine; Fiechter, Michael; Fuchs, Tobias A; Ghadri, Jelena R; Herzog, Bernhard A; Kuhn, Felix; Stehli, Julia; Müller, Ennio; Kazakauskaite, Egle; Gaemperli, Oliver; Kaufmann, Philipp A

    2013-09-10

    Assessment of coronary artery calcification is increasingly used for cardiovascular risk stratification. We evaluated the reliability of calcium-scoring results using a novel iterative reconstruction algorithm (ASIR) on a high-definition 64-slice CT scanner, as such data is lacking. In 50 consecutive patients Agatston scores, calcium mass and volume score were assessed. Comparisons were performed between groups using filtered back projection (FBP) and 20-100% ASIR algorithms. Calcium score was measured in the coronary arteries, signal and noise were measured in the aortic root and left ventricle. In comparison with FBP, use of 20%, 40%, 60%, 80%, and 100% ASIR resulted in reduced image noise between groups (7.7%, 18.8%, 27.9%, 39.86%, and 48.56%, respectively; pASIR algorithms Agatston coronary calcium scoring significantly decreased compared with FBP algorithms (837.3 ± 130.3; 802.2 ± 124.9, 771.5 ± 120.7; 744.7 ± 116.8, 724.5 ± 114.2, and 709.2 ± 112.3 for 0%, 20%, 40%, 60%, 80%, and 100% ASIR, respectively, pASIR results in image noise reduction. However, ASIR image reconstruction techniques for HDCT scans decrease Agatston coronary calcium scores. Thus, one needs to be aware of significant changes of the scoring results caused by different reconstruction methods. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  5. Calcium, potassium and magnesium treatment of Chrysanthemum morifolium cv. "Bi Time" and callogenesis in vitro

    Directory of Open Access Journals (Sweden)

    Borgatto Fábio

    2002-01-01

    Full Text Available The chemical composition and vegetative vigor of the donor plant are essential for the satisfactory performance of explants in vitro. In order to test the effect of potassium, calcium and magnesium nutritional status of Chrysanthemum morifolium plants on callogenesis in vitro, pot plants growing in sand were irrigated with nutrient solution containing different levels of potassium (0; 58.5; 117 and 234 mg L-1, calcium (0; 50; 100 e 200 mg L-1 and magnesium (0;12; 48 e 96 mg L-1. After 30 and 45 days, explants (shoot segments and leaf discs were collected, desinfected and inoculated on MS solid medium supplemented with 0.1 mg L-1 of kinetin and 5.0 mg L-1 of nafthalene acetic acid for callogenesis induction. Callogenesis evaluated as callus fresh weight was affected by nutrients treatment. Callus growth on leaf explants was inversely proporcional to potassium concentration and directly proportional to magnesium concentration in shoot explants. The calcium effect on callogensis of leaf explants was dependent on treatment duration. For 30 days treatment callogenseis was inversely related to calcium concentration and after 45 days was directly related to calcium concentration.

  6. Targeted Learning

    CERN Document Server

    van der Laan, Mark J

    2011-01-01

    The statistics profession is at a unique point in history. The need for valid statistical tools is greater than ever; data sets are massive, often measuring hundreds of thousands of measurements for a single subject. The field is ready to move towards clear objective benchmarks under which tools can be evaluated. Targeted learning allows (1) the full generalization and utilization of cross-validation as an estimator selection tool so that the subjective choices made by humans are now made by the machine, and (2) targeting the fitting of the probability distribution of the data toward the targe

  7. Inositol 1, 4, 5-trisphosphate-dependent nuclear calcium signals regulate angiogenesis and cell motility in triple negative breast cancer.

    Directory of Open Access Journals (Sweden)

    Erika Guimarães

    Full Text Available Increases in nuclear calcium concentration generate specific biological outcomes that differ from those resulting from increased cytoplasmic calcium. Nuclear calcium effects on tumor cell proliferation are widely appreciated; nevertheless, its involvement in other steps of tumor progression is not well understood. Therefore, we evaluated whether nuclear calcium is essential in other additional stages of tumor progression, including key steps associated with the formation of the primary tumor or with the metastatic cascade. We found that nuclear calcium buffering impaired 4T1 triple negative breast cancer growth not just by decreasing tumor cell proliferation, but also by enhancing tumor necrosis. Moreover, nuclear calcium regulates tumor angiogenesis through a mechanism that involves the upregulation of the anti-angiogenic C-X-C motif chemokine 10 (CXCL10-IP10. In addition, nuclear calcium buffering regulates breast tumor cell motility, culminating in less cell invasion, likely due to enhanced vinculin expression, a focal adhesion structural protein. Together, our results show that nuclear calcium is essential for triple breast cancer angiogenesis and cell migration and can be considered as a promising strategic target for triple negative breast cancer therapy.

  8. The proarrhythmic antihistaminic drug terfenadine increases spontaneous calcium release in human atrial myocytes.

    Science.gov (United States)

    Hove-Madsen, Leif; Llach, Anna; Molina, Cristina E; Prat-Vidal, Cristina; Farré, Jordi; Roura, Santiago; Cinca, Juan

    2006-12-28

    Spontaneous calcium release from the sarcoplasmic reticulum in cardiac myocytes plays a central role in cardiac arrhythmogenesis. Compounds intended for therapeutical use that interfere with intracellular calcium handling may therefore have an undesired proarrhythmic potential. Here we have used isolated human atrial myocytes to compare the effect of the proarrhythmic antihistaminic drug terfenadine with the non-proarrhythmic antihistaminic drugs fexofenadine and rupatadine on intracellular calcium homeostasis. Perforated patch-clamp technique was used to measure ionic currents and to detect spontaneous calcium release from the sarcoplasmic reticulum. Our results show that the compound terfenadine, with known arrhythmogenic effects, inhibits L-type calcium current (I(Ca)) with an IC(50) of 185 nM when cells are stimulated at 1.0 Hz. The inhibitory effect of 0.3 muM terfenadine increased from 19+/-4% at stimulation frequency of 0.2 Hz to 63+/-6% at 2.0 Hz. Moreover, terfenadine also increased spontaneous calcium release from the sarcoplasmic reticulum. At a concentration of 1 muM, terfenadine significantly increased the spontaneous Na-Ca exchange current (I(NCX)) frequency from 0.48+/-0.25 to 1.93+/-0.67 s(-1). In contrast, fexofenadine and rupatadine did not change I(Ca) or the frequency of spontaneous I(NCX). We conclude that the proarrhythmic antihistaminic drug terfenadine alters intracellular calcium handling in isolated human atrial myocytes. This experimental model may be suitable to screen for potential arrhythmogenic side-effects of compounds intended for therapeutical use.

  9. Optogenetic monitoring identifies phosphatidylthreonine-regulated calcium homeostasis in Toxoplasma gondii

    Directory of Open Access Journals (Sweden)

    Arunakar Kuchipudi

    2016-05-01

    Full Text Available Toxoplasma gondii is an obligate intracellular parasite, which inflicts acute as well as chronic infections in a wide range of warm-blooded vertebrates. Our recent work has demonstrated the natural occurrence and autonomous synthesis of an exclusive lipid phosphatidylthreonine in T. gondii. Targeted gene disruption of phosphatidylthreonine synthase impairs the parasite virulence due to unforeseen attenuation of the consecutive events of motility, egress and invasion. However, the underlying basis of such an intriguing phenotype in the parasite mutant remains unknown. Using an optogenetic sensor (gene-encoded calcium indicator, GCaMP6s, we show that loss of phosphatidylthreonine depletes calcium stores in intracellular tachyzoites, which leads to dysregulation of calcium release into the cytosol during the egress phase of the mutant. Consistently, the parasite motility and egress phenotypes in the mutant can be entirely restored by ionophore-induced mobilization of calcium. Collectively, our results suggest a novel regulatory function of phosphatidylthreonine in calcium signaling of a prevalent parasitic protist. Moreover, our application of an optogenetic sensor to monitor subcellular calcium in a model intracellular pathogen exemplifies its wider utility to other entwined systems.

  10. Calcium homeostasis and signaling in fungi and their relevance for pathogenicity of yeasts and filamentous fungi

    Directory of Open Access Journals (Sweden)

    Renata Tisi

    2016-09-01

    Full Text Available Though fungi show peculiarities in the purposes and specific traits of calcium signaling pathways, the general scheme and the most important players are well conserved if compared to higher eukaryotes. This provides a powerful opportunity either to investigate shared features using yeast as a model or to exploit fungal specificities as potential targets for antifungal therapies. The sequenced genomes from yeast Saccharomyces cerevisiae, Schizosaccharomyces pombe and the filamentous fungus Neurospora crassa were already published more than ten years ago. More recently the genome sequences of filamentous fungi of Aspergillus genus, some of which threatening pathogens, and dimorphic fungi Ustilago maydis were published, giving the chance to identify several proteins involved in calcium signaling based on their homology to yeast or mammalian counterparts. Nonetheless, unidentified calcium transporters are still present in these organisms which await to be molecularly characterized. Despite the relative simplicity in yeast calcium machinery and the availability of sophisticated molecular tools, in the last years, a number of new actors have been identified, albeit not yet fully characterized. This review will try to describe the state of the art in calcium channels and calcium signaling knowledge in yeast, with particular attention to the relevance of this knowledge with respect to pathological fungi.

  11. Calcium Blood Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... this page: https://medlineplus.gov/labtests/calciumbloodtest.html Calcium Blood Test To use the sharing features on this page, please enable JavaScript. What is a Calcium Blood Test? A calcium blood test measures the ...

  12. Calcium channel regulator Mid1 links TORC2-mediated changes in mitochondrial respiration to autophagy

    OpenAIRE

    Vlahakis, Ariadne; Lopez Muniozguren, Nerea; Powers, Ted

    2016-01-01

    Autophagy is a catabolic process that recycles cytoplasmic contents and is crucial for cell survival during stress. The target of rapamycin (TOR) kinase regulates autophagy as part of two distinct protein complexes, TORC1 and TORC2. TORC1 negatively regulates autophagy according to nitrogen availability. In contrast, TORC2 functions as a positive regulator of autophagy during amino acid starvation, via its target kinase Ypk1, by repressing the activity of the calcium-dependent phosphatase cal...

  13. D1 receptors physically interact with N-type calcium channels to regulate channel distribution and dendritic calcium entry.

    Science.gov (United States)

    Kisilevsky, Alexandra E; Mulligan, Sean J; Altier, Christophe; Iftinca, Mircea C; Varela, Diego; Tai, Chao; Chen, Lina; Hameed, Shahid; Hamid, Jawed; Macvicar, Brian A; Zamponi, Gerald W

    2008-05-22

    Dopamine signaling through D1 receptors in the prefrontal cortex (PFC) plays a critical role in the maintenance of higher cognitive functions, such as working memory. At the cellular level, these functions are predicated to involve alterations in neuronal calcium levels. The dendrites of PFC neurons express D1 receptors and N-type calcium channels, yet little information exists regarding their coupling. Here, we show that D1 receptors potently inhibit N-type channels in dendrites of rat PFC neurons. Using coimmunoprecipitation, we demonstrate the existence of a D1 receptor-N-type channel signaling complex in this region, and we provide evidence for a direct receptor-channel interaction. Finally, we demonstrate the importance of this complex to receptor-channel colocalization in heterologous systems and in PFC neurons. Our data indicate that the N-type calcium channel is an important physiological target of D1 receptors and reveal a mechanism for D1 receptor-mediated regulation of cognitive function in the PFC.

  14. Actein induces calcium release in human breast cancer cells.

    Science.gov (United States)

    Einbond, Linda Saxe; Mighty, Jason; Redenti, Stephen; Wu, Hsan-au

    2013-12-01

    The triterpene glycoside actein from the herb black cohosh preferentially inhibits the growth of breast cancer cells and activates the ER stress response. The ER IP3 receptor and Na,K-ATPase form a signaling microdomain. Since actein is lipophilic, its action may be limited by bioavailability. To develop actein to prevent and treat cancer, we examined the primary targets and combinations with chemotherapy agents, as well as the ability of nanoparticles to enhance the activity. To reveal signaling pathways, we treated human breast and colon cancer, as well as 293T and 293T (NF-κB), cells with actein, and measured effects using the MTT, luciferase promoter, Western blot and histology assays. To assess effects on calcium release, we preloaded cells with the calcium sensitive dye Fura-2. To enhance bioavailability, we conjugated actein to nanoparticle liposomes. Actein strongly inhibited the growth of human breast cancer cells and induced a dose dependent release of calcium into the cytoplasm. The ER IP3 receptor antagonist heparin blocked this release, indicating that the receptor is required for activity. Heparin partially blocked the growth inhibitory effect, while the MEK inhibitor U0126 enhanced it. Consistent with this, actein synergized with the ER mobilizer thapsigargin. Further, actein preferentially inhibited the growth of 293T (NF-κB) cells. Nanoparticle liposomes increased the growth inhibitory activity of actein. Actein alters the activity of the ER IP3 receptor and Na,K-ATPase, induces calcium release and modulates the NF-κB and MEK pathways and may be worthwhile to explore to prevent and treat breast cancer. © 2013.

  15. Rates of calcium carbonate removal from soils.

    NARCIS (Netherlands)

    Breemen, van N.; Protz, R.

    1988-01-01

    Mean annual rates of calcium carbonate removal from soils in a subarctic climate estimated from data on two chronosequences of calcareous storm ridges, appeared to be relatively constant through time. Concentrations of dissolved calcium carbonate in the soil solution in the study sites calculated

  16. Calcium and M'yocardial Infarction

    African Journals Online (AJOL)

    1974-03-16

    Mar 16, 1974 ... Urinary excretion of calcium tended to be even lower in these .... 16 March 1974. S.A. MEDICAL JOURNAL. 525. 150. 50. Fig. 5. Urine calcium in myocardial infarction (means and standard error relative to age). AGE OF PATIENT .... Plasma proteins and blood urea were also measured in. 10 consecutive ...

  17. Calcium, snails, and birds: a case study

    Directory of Open Access Journals (Sweden)

    R. Mänd

    2000-10-01

    Full Text Available Recent studies have shown that wild birds breeding in acidified areas have difficulties with obtaining sufficient calcium for their eggshells, and that the cause of it is the shortage of land snails. Many birds have to search for Ca-rich snail shells on a daily basis during egg production. Molluscs depend on litter calcium, which has decreased due to acidification of the environment. Calcium limitation may be a widespread phenomenon also in non-acidified, naturally Ca-poor areas. The problem is that while in the latter areas the time for development of specific adaptations may have been sufficient, then in acidified areas, on the contrary, calcium shortage is a recent phenomenon. Therefore, since the extent of calcium limitation in non-acidified areas is hard to derive from observational data, experimental approach is needed. We provide experimental evidence that specific calcium deficit does affect reproductive traits also in the birds breeding in naturally base-poor habitats. Our study was conducted in a heterogeneous woodland area in Estonia containing deciduous forest patches as well as base-poor pine forest with low snail abundance. Ca supplementation, using snail shell and chicken eggshell fragments, was carried out for pied flycatchers and great tits. Extra calcium affected positively several reproductive traits like egg volume and eggshell thickness, start of breeding, and fledglings’ parameters. The negative relationship between calcium availability and lay-date suggests that birds adjust their breeding tactics to conditions of Ca deficiency, for example, by postponing laying.

  18. 21 CFR 182.8223 - Calcium pyrophosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pyrophosphate. 182.8223 Section 182.8223 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8223 Calcium...

  19. 21 CFR 182.8217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium phosphate. 182.8217 Section 182.8217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium...

  20. Elements from chlorine to calcium nuclear reactions

    CERN Document Server

    Kunz, Wunibald

    1968-01-01

    Nuclear Tables: Part II Nuclear Reactions, Volume 3: The Elements from Chlorine to Calcium contains tabulations of the nuclear reaction values of elements chlorine, argon, potassium, and calcium. These tabulations provide the calculated Q-values of the elements and their isotopes. This book will be of value to general chemistry researchers.

  1. Role of calcium in selenium cataract.

    Science.gov (United States)

    Shearer, T R; David, L L

    The purpose of this research was to test the role of certain minerals in the formation of cataract caused by an overdose of selenium. Several pieces of information indicated that lenticular calcium may play an important role in selenite cataractogenesis: 1) Lens calcium concentrations in selenite treated rats were increased more than 5-fold, and the increase in lens calcium was localized in the nucleus. 2) Lens calcium concentrations were elevated at least one full day before actual formation of nuclear cataract, but serum calcium levels were not changed. 3) In older rats not susceptible to selenite cataract, lens calcium was not significantly increased. 4) No evidence was found for a generalized disruption in lens permeability, since no major changes in lens water, sodium, and potassium levels were observed, and 5) when levels of calcium observed in selenite cataract were added to solutions of soluble proteins from rat lenses, light scattering was increased. Selenium-overdose cataracts may provide an important model for studies on the role of calcium in cataractogenesis.

  2. Adding calcium improves lithium ferrite core

    Science.gov (United States)

    Lessoff, H.

    1969-01-01

    Adding calcium increases uniformity of grain growth over a wide range of sintering temperatures and reduces porosity within the grain. Ferrite cores containing calcium have square hysteresis loops and high curie temperatures, making them useful in coincident current memories of digital electronic computers.

  3. ALG-2, a multifunctional calcium binding protein?

    DEFF Research Database (Denmark)

    Tarabykina, Svetlana; Mollerup, Jens; Winding Gojkovic, P.

    2004-01-01

    ALG-2 was originally discovered as a pro-apoptotic protein in a genetic screen. Due to its ability to bind calcium with high affinity it was postulated to provide a link between the known effect of calcium in programmed cell death and the molecular death execution machinery. This review article...

  4. Comparison of Serum Calcium and Magnesium Between ...

    African Journals Online (AJOL)

    The present study compared serum calcium and magnesium in forty preeclamptic (cases) and forty normotensive (control) pregnant women matched for age, parity, and socioeconomic status. Serum calcium and magnesium levels were measured using atomic absorption spectrophotometer. Statistical analysis was done ...

  5. Dairy Dilemma: Are You Getting Enough Calcium?

    Science.gov (United States)

    ... body also needs vitamin D to absorb calcium. Nutrition surveys have shown that most people in the U.S. aren’t getting the calcium they need. If you’re avoiding milk and dairy ... taking nutritional supplements and choosing reduced-lactose or non-dairy ...

  6. CALCIUM AND THE PREVENTION OF COLON CANCER

    NARCIS (Netherlands)

    WELBERG, JWM; KLEIBEUKER, JH; VANDERMEER, R; MULDER, NH; DEVRIES, EGE

    1991-01-01

    Diet is a major determinant of colon cancer risk. Calcium may protect against colon cancer, presumably by binding cytotoxic bile acids and fatty acids. Numerous studies support this proposition. In subjects at risk for colon cancer oral calcium supplementation has been shown to reduce rectal

  7. Bespuiten met calcium kan neusrot voorkomen

    NARCIS (Netherlands)

    Blom-Zandstra, Greet; Marcelis, L.F.M.

    2000-01-01

    Oorzaak van neusrot bij paprika is een calciumtekort in de vrucht. Een bespuiting met calcium vlak na de bloei heeft een zeer gunstig effect. In bijgaande tabel gegevens over het effect van spuiten met calcium op het optreden van neusrot bij paprika

  8. Identification of mitochondrial DNA polymorphisms that alter mitochondrial matrix pH and intracellular calcium dynamics.

    Directory of Open Access Journals (Sweden)

    An-a Kazuno

    2006-08-01

    Full Text Available Mitochondrial DNA (mtDNA is highly polymorphic, and its variations in humans may contribute to individual differences in function as well as susceptibility to various diseases such as Parkinson disease, Alzheimer disease, bipolar disorder, and cancer. However, it is unclear whether and how mtDNA polymorphisms affect intracellular function, such as calcium signaling or pH regulation. Here we searched for mtDNA polymorphisms that have intracellular functional significance using transmitochondrial hybrid cells (cybrids carrying ratiometric Pericam (RP, a fluorescent calcium indicator, targeted to the mitochondria and nucleus. By analyzing the entire mtDNA sequence in 35 cybrid lines, we found that two closely linked nonsynonymous polymorphisms, 8701A and 10398A, increased the basal fluorescence ratio of mitochondria-targeted RP. Mitochondrial matrix pH was lower in the cybrids with 8701A/10398A than it was in those with 8701G/10398G, suggesting that the difference observed by RP was mainly caused by alterations in mitochondrial calcium levels. Cytosolic calcium response to histamine also tended to be higher in the cybrids with 8701A/10398A. It has previously been reported that 10398A is associated with an increased risk of Parkinson disease, Alzheimer disease, bipolar disorder, and cancer, whereas 10398G associates with longevity. Our findings suggest that these mtDNA polymorphisms may play a role in the pathophysiology of these complex diseases by affecting mitochondrial matrix pH and intracellular calcium dynamics.

  9. Reciprocal Interaction of Dendrite Geometry and Nuclear Calcium-VEGFD Signaling Gates Memory Consolidation and Extinction.

    Science.gov (United States)

    Hemstedt, Thekla J; Bengtson, C Peter; Ramírez, Omar; Oliveira, Ana M M; Bading, Hilmar

    2017-07-19

    Nuclear calcium is an important signaling end point in synaptic excitation-transcription coupling that is critical for long-term neuroadaptations. Here, we show that nuclear calcium acting via a target gene, VEGFD, is required for hippocampus-dependent fear memory consolidation and extinction in mice. Nuclear calcium-VEGFD signaling upholds the structural integrity and complexity of the dendritic arbor of CA1 neurons that renders those cells permissive for the efficient generation of synaptic input-evoked nuclear calcium transients driving the expression of plasticity-related genes. Therefore, the gating of memory functions rests on the reciprocally reinforcing maintenance of an intact dendrite geometry and a functional synapse-to-nucleus communication axis. In psychiatric and neurodegenerative disorders, therapeutic application of VEGFD may help to stabilize dendritic structures and network connectivity, which may prevent cognitive decline and could boost the efficacy of extinction-based exposure therapies. SIGNIFICANCE STATEMENT This study uncovers a reciprocal relationship between dendrite geometry, the ability to generate nuclear calcium transients in response to synaptic inputs, and the subsequent induction of expression of plasticity-related and dendritic structure-preserving genes. Insufficient nuclear calcium signaling in CA1 hippocampal neurons and, consequently, reduced expression of the nuclear calcium target gene VEGFD, a dendrite maintenance factor, leads to reduced-complexity basal dendrites of CA1 neurons, which severely compromises the animals' consolidation of both memory and extinction memory. The structure-protective function of VEGFD may prove beneficial in psychiatric disorders as well as neurodegenerative and aging-related conditions that are associated with loss of neuronal structures, dysfunctional excitation-transcription coupling, and cognitive decline. Copyright © 2017 the authors 0270-6474/17/376946-10$15.00/0.

  10. Calcium and caffeine interaction in increased calcium balance in ovariectomized rats

    Directory of Open Access Journals (Sweden)

    Sandra Tavares da Silva

    2013-06-01

    Full Text Available OBJECTIVE: This study investigated the effects of caffeine intake associated with inadequate or adequate calcium intake in laparotomized or ovariectomized rats by means of the calcium balance. Forty adults Wistar rats were ovariectomized or laparotomized. METHODS: The animals (n=40 were randomly placed in eight groups receiving the AIN-93 diet with 100% or 50% of the recommended calcium intake with or without added caffeine (6mg/kg/day. The animals were kept in individuals metabolic cages at a temperature of 24°±2ºC, light/dark cycles of 12/12 hours, and deionized water available ad libitum. On the 8th week of the experiment, food consumption was measured and 24-hour urine and 4-day feces were collected to determine calcium balance [Balance=Ca intake-(Urinary Ca+Fecal Ca]. RESULTS: Animals with adequate calcium intake presented higher balances and rates of calcium absorption and retention (p<0.05 than those with inadequate calcium intake, regardless of caffeine intake (p<0.05. Caffeine intake did not affect urinary calcium excretion but increased balance (p<0.05 in the groups with adequate calcium intake. CONCLUSION: Adequate calcium intake attenuated the negative effects of estrogen deficiency and improved calcium balance even in the presence of caffeine.

  11. Store-operated calcium entry is essential for glial calcium signalling in CNS white matter.

    Science.gov (United States)

    Papanikolaou, M; Lewis, A; Butt, A M

    2017-02-28

    'Calcium signalling' is the ubiquitous response of glial cells to multiple extracellular stimuli. The primary mechanism of glial calcium signalling is by release of calcium from intracellular stores of the endoplasmic reticulum (ER). Replenishment of ER Ca(2+) stores relies on store-operated calcium entry (SOCE). However, despite the importance of calcium signalling in glial cells, little is known about their mechanisms of SOCE. Here, we investigated SOCE in glia of the mouse optic nerve, a typical CNS white matter tract that comprises bundles of myelinated axons and the oligodendrocytes and astrocytes that support them. Using quantitative RT-PCR, we identified Orai1 channels, both Stim1 and Stim2, and the transient receptor potential M3 channel (TRPM3) as the primary channels for SOCE in the optic nerve, and their expression in both astrocytes and oligodendrocytes was demonstrated by immunolabelling of optic nerve sections and cultures. The functional importance of SOCE was demonstrated by fluo-4 calcium imaging on isolated intact optic nerves and optic nerve cultures. Removal of extracellular calcium ([Ca(2+)]o) resulted in a marked depletion of glial cytosolic calcium ([Ca(2+)]i), which recovered rapidly on restoration of [Ca(2+)]o via SOCE. 2-aminoethoxydiphenylborane (2APB) significantly decreased SOCE and severely attenuated ATP-mediated calcium signalling. The results provide evidence that Orai/Stim and TRPM3 are important components of the 'calcium toolkit' that underpins SOCE and the sustainability of calcium signalling in white matter glia.

  12. Selective laser sintering of calcium phosphate materials for orthopedic implants

    Science.gov (United States)

    Lee, Goonhee

    Two technologies, Solid Freeform Fabrication (SFF) and bioceramics are combined in this work to prepare bone replacement implants with complex geometry. SFF has emerged as a crucial technique for rapid prototyping in the last decade. Selective Laser Sintering (SLS) is one of the established SFF manufacturing processes that can build three-dimensional objects directly from computer models without part-specific tooling or human intervention. Meanwhile, there have been great efforts to develop implantable materials that can assist in regeneration of bone defects and injuries. However, little attention has been focused in shaping bones from these materials. The main thrust of this research was to develop a process that can combine those two separate efforts. The specific objective of this research is to develop a process that can construct bone replacement material of complex geometry from synthetic calcium phosphate materials by using the SLS process. The achievement of this goal can have a significant impact on the quality of health care in the sense that complete custom-fit bone and tooth structures suitable for implantation can be prepared within 24--48 hours of receipt of geometric information obtained either from patient Computed Tomographic (CT) data, from Computer Aided Design (CAD) software or from other imaging systems such as Magnetic Resonance Imaging (MRI) and Holographic Laser Range Imaging (HLRI). In this research, two different processes have been developed. First is the SLS fabrication of porous bone implants. In this effort, systematic procedures have been established and calcium phosphate implants were successfully fabricated from various sources of geometric information. These efforts include material selection and preparation, SLS process parameter optimization, and development of post-processing techniques within the 48-hour time frame. Post-processing allows accurate control of geometry and of the chemistry of calcium phosphate, as well as

  13. Endoplasmic reticulum calcium stores in dendritic spines.

    Science.gov (United States)

    Segal, Menahem; Korkotian, Eduard

    2014-01-01

    Despite decades of research, the role of calcium stores in dendritic spines structure, function and plasticity is still debated. The reasons for this may have to do with the multitude of overlapping calcium handling machineries in the neuron, including stores, voltage and ligand gated channels, pumps and transporters. Also, different cells in the brain are endowed with calcium stores that are activated by different receptor types, and their differential compartmentalization in dendrites, spines and presynaptic terminals complicates their analysis. In the present review we address several key issues, including the role of calcium stores in synaptic plasticity, their role during development, in stress and in neurodegenerative diseases. Apparently, there is increasing evidence for a crucial role of calcium stores, especially of the ryanodine species, in synaptic plasticity and neuronal survival.

  14. Application of Calcium Phosphate Materials in Dentistry

    Directory of Open Access Journals (Sweden)

    Jabr S. Al-Sanabani

    2013-01-01

    Full Text Available Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1 application of calcium phosphate into various fields in dentistry; (2 improving mechanical properties of calcium phosphate; (3 biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields.

  15. Calcium phosphate: a substitute for aluminum adjuvants?

    Science.gov (United States)

    Masson, Jean-Daniel; Thibaudon, Michel; Bélec, Laurent; Crépeaux, Guillemette

    2017-03-01

    Calcium phosphate was used as an adjuvant in France in diphtheria, tetanus, pertussis and poliomyelitis vaccines. It was later completely substituted by alum salts in the late 80's, but it still remains as an approved adjuvant for the World Health Organization for human vaccination. Area covered: Thus, calcium phosphate is now considered as one of the substances that could replace alum salts in vaccines. The aim of this paper is to draw a review of existing data on calcium phosphate as an adjuvant in order to bring out the strengths and weaknesses for its use on a large scale. Expert commentary: Calcium phosphate is a compound naturally present in the organism, safe and already used in human vaccination. Beyond comparisons with the other adjuvants, calcium phosphate represents a good candidate to replace or to complete alum salts as a vaccine adjuvant.

  16. The calcium and vitamin D controversy

    DEFF Research Database (Denmark)

    Abrahamsen, Bo

    2017-01-01

    or subanalyses while maintaining balancing. Though large clinical RCTs currently evaluate the effects of higher vitamin D doses (equivalent to 50–83 μg/d) there is no current research effort regarding the calcium controversy. In the absence of such studies it is not possible to provide clinicians with evidence......Areas of the world where vitamin D levels are low for months of the year and intakes of calcium are high have a high prevalence of osteoporosis and cardiovascular disease. This suggests a public health message of avoiding calcium supplements and increasing vitamin D intake. No message could be more...... welcome as vitamin D can be given as a bolus while calcium must be taken daily and may be poorly tolerated. This approach is based on no evidence from intervention studies. Randomized controlled trials (RCTs) suggest that vitamin D given with calcium elicits a small reduction in fracture risk and deaths...

  17. PKA controls calcium influx into motor neurons during a rhythmic behavior.

    Directory of Open Access Journals (Sweden)

    Han Wang

    Full Text Available Cyclic adenosine monophosphate (cAMP has been implicated in the execution of diverse rhythmic behaviors, but how cAMP functions in neurons to generate behavioral outputs remains unclear. During the defecation motor program in C. elegans, a peptide released from the pacemaker (the intestine rhythmically excites the GABAergic neurons that control enteric muscle contractions by activating a G protein-coupled receptor (GPCR signaling pathway that is dependent on cAMP. Here, we show that the C. elegans PKA catalytic subunit, KIN-1, is the sole cAMP target in this pathway and that PKA is essential for enteric muscle contractions. Genetic analysis using cell-specific expression of dominant negative or constitutively active PKA transgenes reveals that knockdown of PKA activity in the GABAergic neurons blocks enteric muscle contractions, whereas constitutive PKA activation restores enteric muscle contractions to mutants defective in the peptidergic signaling pathway. Using real-time, in vivo calcium imaging, we find that PKA activity in the GABAergic neurons is essential for the generation of synaptic calcium transients that drive GABA release. In addition, constitutively active PKA increases the duration of calcium transients and causes ectopic calcium transients that can trigger out-of-phase enteric muscle contractions. Finally, we show that the voltage-gated calcium channels UNC-2 and EGL-19, but not CCA-1 function downstream of PKA to promote enteric muscle contractions and rhythmic calcium influx in the GABAergic neurons. Thus, our results suggest that PKA activates neurons during a rhythmic behavior by promoting presynaptic calcium influx through specific voltage-gated calcium channels.

  18. Strontium Substitution for Calcium in Lithogenesis

    Science.gov (United States)

    Blaschko, Sarah D.; Chi, Thomas; Miller, Joe; Flechner, Lawrence; Fakra, Sirine; Kapahi, Pankaj; Kahn, Arnold; Stoller, Marshall L.

    2013-01-01

    Purpose Strontium has chemical similarity to calcium, which enables the replacement of calcium by strontium in biomineralization processes. Incorporating strontium into human bone and teeth has been studied extensively but little research has been performed of the incorporation of strontium into urinary calculi. We used synchrotron based x-ray fluorescence and x-ray absorption techniques to examine the presence of strontium in different types of human kidney stones. Materials and Methods Multiple unique human stone samples were obtained via consecutive percutaneous nephrolithotomies/ureteroscopies. A portion of each stone was sent for standard laboratory analysis and a portion was retained for x-ray fluorescence and x-ray absorption measurements. X-ray fluorescence and x-ray absorption measurements determined the presence, spatial distribution and speciation of strontium in each stone sample. Results Traditional kidney stone analyses identified calcium oxalate, calcium phosphate, uric acid and cystine stones. X-ray fluorescence measurements identified strontium in all stone types except pure cystine. X-ray fluorescence elemental mapping of the samples revealed co-localization of calcium and strontium. X-ray absorption measurements of the calcium phosphate stone showed strontium predominately present as strontium apatite. Conclusions Advanced x-ray fluorescence imaging identified strontium in all calcium based stones, present as strontium apatite. This finding may be critical since apatite is thought to be the initial nidus for calcium stone formation. Strontium is not identified by standard laboratory stone analyses. Its substitution for calcium can be reliably identified in stones from multiple calcium based stone formers, which may offer opportunities to gain insight into early events in lithogenesis. PMID:23260568

  19. A comparison of total calcium, corrected calcium, and ionized calcium concentrations as indicators of calcium homeostasis among hypoalbuminemic dogs requiring intensive care.

    Science.gov (United States)

    Sharp, Claire R; Kerl, Marie E; Mann, F A

    2009-12-01

    (1) To evaluate whether total calcium (tCa) correlates with ionized calcium (iCa) in hypoalbuminemic dogs; (2) to evaluate whether calcium adjusted for albumin (Alb), or total protein (TP), or both accurately predict iCa concentrations and hence can be used to monitor calcium homeostasis in critically ill hypoalbuminemic dogs; and (3) to evaluate factors associated with any potential discrepancy in calcium classification between corrected total and ionized values. Prospective observational clinical study. Small animal intensive care unit in a veterinary medical teaching hospital. Twenty-eight client-owned dogs with hypoalbuminemia. None. iCa was determined using ion-specific electrode methodology, on heparinized plasma. The tCa concentration was adjusted for Alb and TP using published equations. In total 29% (8/28) of the hypoalbuminemic, critically ill dogs in this study were hypocalcemic at intensive care unit admission, as determined by iCa measurement. Corrected calcium values failed to accurately classify calcium status in 67.9% and 64.3% of cases, according to whether the Alb-adjusted or TP-adjusted values, respectively, were used. The sensitivity and specificity of the tCa to evaluate hypocalcemia was 100% and 47%, respectively. The sensitivity and specificity of the correction formulae were 37.5% and 79% for the Alb-adjusted values and 37.5% and 74% for TP-adjusted values. tCa overestimated the presence of hypocalcemia and underestimated the presence of normocalcemia, while corrected calcium values overestimated the presence of normocalcemia and underestimated the presence of hypocalcemia. Calcium homeostasis in hypoalbuminemic critically ill dogs should be evaluated by iCa concentrations rather than tCa or calcium adjusted for Alb or TP. Given that tCa has 100% sensitivity for detecting hypocalcemia in this population it is recommended that all hypoalbuminemic and critically ill patients with low tCa should be evaluated with an iCa measurement.

  20. Tuning local calcium availability: cell-type-specific immobile calcium buffer capacity in hippocampal neurons.

    Science.gov (United States)

    Matthews, Elizabeth A; Schoch, Susanne; Dietrich, Dirk

    2013-09-04

    It has remained difficult to ascribe a specific functional role to immobile or fixed intracellular calcium buffers in central neurons because the amount of these buffers is unknown. Here, we explicitly isolated the fixed buffer fraction by prolonged whole-cell patch-clamp dialysis and quantified its buffering capacity in murine hippocampal slices using confocal calcium imaging and the "added-buffer" approach. In dentate granule cells, the calcium binding ratio (κ) after complete washout of calbindin D28k (Cb), κfixed, displayed a substantial value of ∼100. In contrast, in CA1 oriens lacunosum moleculare (OLM) interneurons, which do not contain any known calcium-binding protein(s), κfixed amounted to only ∼30. Based on these values, a theoretical analysis of dendritic spread of calcium after local entry showed that fixed buffers, in the absence of mobile species, decrease intracellular calcium mobility 100- and 30-fold in granule cells and OLM cells, respectively, and thereby strongly slow calcium signals. Although the large κfixed alone strongly delays the spread of calcium in granule cells, this value optimizes the benefits of additionally expressing the mobile calcium binding protein Cb. With such high κfixed, Cb effectively increases the propagation velocity to levels seen in OLM cells and, contrary to expectation, does not affect the peak calcium concentration close to the source but sharpens the spatial and temporal calcium gradients. The data suggest that the amount of fixed buffers determines the temporal availability of calcium for calcium-binding partners and plays a pivotal role in setting the repertoire of cellular calcium signaling regimens.

  1. Diagnosis and assessment of skeletal related disease using calcium 41

    Science.gov (United States)

    Hillegonds, Darren J [Oakland, CA; Vogel, John S [San Jose, CA; Fitzgerald, Robert L [Encinitas, CA; Deftos, Leonard J [Del Mar, CA; Herold, David [Del Mar, CA; Burton, Douglas W [San Diego, CA

    2012-05-15

    A method of determining calcium metabolism in a patient comprises the steps of administering radioactive calcium isotope .sup.41Ca to the patient, allowing a period of time to elapse sufficient for dissemination and reaction of the radioactive calcium isotope .sup.41Ca by the patient, obtaining a sample of the radioactive calcium isotope .sup.41Ca from the patient, isolating the calcium content of the sample in a form suitable for precise measurement of isotopic calcium concentrations, and measuring the calcium content to determine parameters of calcium metabolism in the patient.

  2. Non-calcium desulphurisation technologies

    Energy Technology Data Exchange (ETDEWEB)

    Qian Zhu [IEA Clean Coal Centre, London (United Kingdom)

    2010-06-15

    Flue gas desulphurisation (FGD) is traditionally based on limestone/lime sorbent. The majority of the installed FGD systems worldwide use limestone or lime as sorbent. However, technologies are rapidly evolving that allow desulphurisation in regions where there are limited resources of lime or limestone. These technologies provide alternatives to limestone/lime scrubbers for efficient and cost effective control of SO{sub 2} emissions from coal combustion. This report reviews the existing and emerging non-calcium based FGD processes as well as FGD technologies currently under development that apply new concepts and different approaches. It looks at the fundamentals and features of these processes, the recent technical advances and their applications in coal-fired power plants. The capital and operating costs of the processes are evaluated where information available. 66 refs., 15 figs., 10 tabs.

  3. Calcium-sensitive immunoaffinity chromatography

    DEFF Research Database (Denmark)

    Henriksen, Maiken L; Lindhardt Madsen, Kirstine; Skjoedt, Karsten

    2014-01-01

    Immunoaffinity chromatography is a powerful fractionation technique that has become indispensable for protein purification and characterization. However, it is difficult to retrieve bound proteins without using harsh or denaturing elution conditions, and the purification of scarce antigens...... to homogeneity may be impossible due to contamination with abundant antigens. In this study, we purified the scarce, complement-associated plasma protein complex, collectin LK (CL-LK, complex of collectin liver 1 and kidney 1), by immunoaffinity chromatography using a calcium-sensitive anti-collectin-kidney-1 m...... chromatography was superior to the traditional immunoaffinity chromatographies and resulted in a nine-fold improvement of the purification factor. The technique is applicable for the purification of proteins in complex mixtures by single-step fractionation without the denaturation of eluted antigens...

  4. Comparison of 25-hydroxy vitamin D, calcium and alkaline phosphatase levels in epileptic and non-epileptic children.

    Science.gov (United States)

    Razazizan, Nazanin; Mirmoeini, Maryam; Daeichin, Sara; Ghadiri, Keyghobad

    2013-09-01

    There is evidence for the existence of bone disease in epileptic patients. The goal of this study was the comparison of serum levels calcium, alkaline phosphatase (ALKP) and 25-hydroxyvitamin D in ambulatory epileptic children in order to evaluate the bone metabolism in epileptic patients. In this prospective analytical study 48 ambulatory epileptic children who were treated by antiepileptic drugs for atleast 6 months as case group compared with 48 children who were age and gender matched as control group. Patients with any neurological deficits and other systemic diseases were excluded. Data was collected by questionnaire and analyzed by spss software version 18. Mean of calcium level in case and control groups was 9.91 ±0.675 and 10.08 ±0.331 mg/dl respectively, means of ALKP in case were 703 and 607.75 IU/L respectively. Only difference between the ALKP were significant. Calcium levels, ALKP and vitmain D in any of the two groups were not associated with age and a sex but ALKP level in patients was higher and it was statistically siginificant. Calcium levels, ALKP and vitamin D in patients with drug type, dosage and duration of treatment were irrelevant. The results of this study showed that calcium and vitamin D levels were in normal ranges in epileptic and control groups but ALKP levels were significantly higher in epileptic group which can be a valuable indicator of bone metabolism in these patients.

  5. Support for calcium channel gene defects in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Lu Ake Tzu-Hui

    2012-12-01

    Full Text Available Abstract Background Alternation of synaptic homeostasis is a biological process whose disruption might predispose children to autism spectrum disorders (ASD. Calcium channel genes (CCG contribute to modulating neuronal function and evidence implicating CCG in ASD has been accumulating. We conducted a targeted association analysis of CCG using existing genome-wide association study (GWAS data and imputation methods in a combined sample of parent/affected child trios from two ASD family collections to explore this hypothesis. Methods A total of 2,176 single-nucleotide polymorphisms (SNP (703 genotyped and 1,473 imputed covering the genes that encode the α1 subunit proteins of 10 calcium channels were tested for association with ASD in a combined sample of 2,781 parent/affected child trios from 543 multiplex Caucasian ASD families from the Autism Genetics Resource Exchange (AGRE and 1,651 multiplex and simplex Caucasian ASD families from the Autism Genome Project (AGP. SNP imputation using IMPUTE2 and a combined reference panel from the HapMap3 and the 1,000 Genomes Project increased coverage density of the CCG. Family-based association was tested using the FBAT software which controls for population stratification and accounts for the non-independence of siblings within multiplex families. The level of significance for association was set at 2.3E-05, providing a Bonferroni correction for this targeted 10-gene panel. Results Four SNPs in three CCGs were associated with ASD. One, rs10848653, is located in CACNA1C, a gene in which rare de novo mutations are responsible for Timothy syndrome, a Mendelian disorder that features ASD. Two others, rs198538 and rs198545, located in CACN1G, and a fourth, rs5750860, located in CACNA1I, are in CCGs that encode T-type calcium channels, genes with previous ASD associations. Conclusions These associations support a role for common CCG SNPs in ASD.

  6. Relationship of calcium absorption with 25(OH)D and calcium intake in children with rickets.

    Science.gov (United States)

    Thacher, Tom D; Abrams, Steven A

    2010-11-01

    Nutritional rickets has long been considered a disease caused by vitamin D deficiency, but recent data indicate that inadequate dietary calcium intake is an important cause of rickets, particularly in tropical countries. Children with rickets due to calcium deficiency do not have very low 25(OH)D concentrations, and serum 1,25(OH)(2) D values are markedly elevated. Studies of Nigerian children with rickets demonstrated they have high fractional calcium absorption. A high-phytate diet was demonstrated to increase calcium absorption compared with the fasting state, and enzymatic dephytinization did not significantly improve calcium absorption. When given vitamin D, children with rickets have a marked increase in 1,25(OH)(2) D concentrations without any change in fractional calcium absorption. No positive relationship was found between fractional calcium absorption and serum 25(OH)D concentrations in children on low-calcium diets. More research is needed to understand the interaction between calcium and vitamin D and the role of vitamin D in calcium absorption. © 2010 International Life Sciences Institute.

  7. Calcium phosphate scaffold from biogenic calcium carbonate by fast ambient condition reactions

    Science.gov (United States)

    Dutta, Abhishek; Fermani, Simona; Arjun Tekalur, Srinivasan; Vanderberg, Abigail; Falini, Giuseppe

    2011-12-01

    Calcium phosphate biogenic materials are biocompatible and promote bioactivity and osteoconductivity, which implies their natural affinity and tendency to bond directly to bones subsequently replacing the host bone after implantation owing to its biodegradability. Calcium hydrogen phosphate dihydrate, CaHPO 4·2H 2O, is known to be a nucleation precursor, in aqueous solutions, for apatitic calcium phosphates and, hence, a potential starting material for bone substitutes. Numerous approaches, via hydrothermal and ambient synthetic routes, have been used to produce calcium phosphate from biogenic calcium carbonate, taking advantage of the peculiar architecture and composition of the latter. In this article, the lamellar region of the cuttlefish bone ( Sepia officinalis) was used as a framework for the organized deposition of calcium phosphate crystals, at ambient conditions via a fast procedure involving an amorphous calcium carbonate intermediate, and ending with a conversion to calcium phosphate and a fixation procedure, thereby resulting in direct conversion of biogenic calcium carbonate into calcium phosphates at ambient conditions from the scale of months to hours.

  8. Delayed serum calcium biochemical response to successful parathyroidectomy in primary hyperparathyroidism.

    Science.gov (United States)

    Alabdulkarim, Yousof; Nassif, Edgard

    2010-01-01

    Parathyroidectomy is considered the standard treatment for primary hyperparathyroidism, however, though the onset of biochemical response is variable and is different from one patient to the other. To evaluate the onset of systemic response and the biochemical normalization of serum calcium levels to a successful surgery. In a retrospective fashion, we collected clinical data from 303 patients admitted to our hospital between 2005 and 2008, with a diagnosis of primary hyperparathyroidism after sestamibi localization. The pathology reports, parathyroidectomy results, the preoperative and postoperative parathormone (PTH) and serum calcium levels were reviewed. Response of each patient to the surgery was studied and all the data were analyzed to determine how fast the serum calcium levels drop. The majority of patients (72.9%, 221/303) showed a decrease in their serum calcium levels to normal values within 48 h. While in 40 patients it took 72 hours and 42 patients (13.8%) had a delayed normalization for more than 72 h. The pathology in the PH group was predominantly of a single adenoma 80.9% vs.19.1 with hyperplasia with a P of 0.03. Preoperative parathyroid hormone PTH elevation was not significantly deferent between the two groups (PH and EN) with a mean of 7.9±5.36 vs. 7.41±14.5 pmol/L respectively with a P of 0.43. The majority of patients with primary hyperparathyroidism (PHP) respond to parathyroidectomy in the form of normalization of their serum calcium levels and PTH within 48 h; however, a certain group of patients will need more than 3 days.

  9. In vitro antioxidant properties of calcium dobesilate.

    Science.gov (United States)

    Brunet, J; Farine, J C; Garay, R P; Hannaert, P

    1998-01-01

    Calcium dobesilate, a vascular protective agent, was tested in vitro for its scavenging action against oxygen free radicals. Calcium dobesilate was as potent as rutin to scavenge hydroxyl radicals (IC50 = 1.1 vs 0.7 microM, respectively). It was also able to scavenge superoxide radicals, but with 23 times less potency than rutin (IC50 = 682 vs 30 microM, respectively). Calcium dobesilate significantly reduced platelet activating factor (PAF)-induced chemiluminescence in human PMN cells and lipid peroxidation by oxygen free radicals in human erythrocyte membranes, although these actions required calcium dobesilate concentrations > or = 50 microM. Finally, in cultured bovine aortic endothelial cells, magnesium dobesilate reduced the increase in cytosolic free calcium induced by hydrogen peroxide and inhibited phenazine methosulfate-induced cell potassium loss. In conclusion, calcium dobesilate was effective in scavenging hydroxyl radicals in vitro, at therapeutically relevant concentrations. Conversely, higher concentrations of the compound were required to scavenge superoxide radicals or to protect the cells against the deleterious effects of intracellular reactive oxygen species. Further studies in vivo are required to determine if these antioxidant properties of calcium dobesilate can play a role in its vascular protective mechanisms.

  10. Intracellular sphingosine releases calcium from lysosomes

    Science.gov (United States)

    Höglinger, Doris; Haberkant, Per; Aguilera-Romero, Auxiliadora; Riezman, Howard; Porter, Forbes D; Platt, Frances M; Galione, Antony; Schultz, Carsten

    2015-01-01

    To elucidate new functions of sphingosine (Sph), we demonstrate that the spontaneous elevation of intracellular Sph levels via caged Sph leads to a significant and transient calcium release from acidic stores that is independent of sphingosine 1-phosphate, extracellular and ER calcium levels. This photo-induced Sph-driven calcium release requires the two-pore channel 1 (TPC1) residing on endosomes and lysosomes. Further, uncaging of Sph leads to the translocation of the autophagy-relevant transcription factor EB (TFEB) to the nucleus specifically after lysosomal calcium release. We confirm that Sph accumulates in late endosomes and lysosomes of cells derived from Niemann-Pick disease type C (NPC) patients and demonstrate a greatly reduced calcium release upon Sph uncaging. We conclude that sphingosine is a positive regulator of calcium release from acidic stores and that understanding the interplay between Sph homeostasis, calcium signaling and autophagy will be crucial in developing new therapies for lipid storage disorders such as NPC. DOI: http://dx.doi.org/10.7554/eLife.10616.001 PMID:26613410

  11. Calcium content of different compositions of gallstones and pathogenesis of calcium carbonate gallstones.

    Science.gov (United States)

    Yu, Ji-Kuen; Pan, Huichin; Huang, Shing-Moo; Huang, Nan-Lan; Yao, Chung-Chin; Hsiao, Kuang-Ming; Wu, Chew-Wun

    2013-01-01

    Our aim was to investigate the calcium content of different gallstone compositions and the pathogenic mechanisms of calcium carbonate gallstones. Between August 2001 and July 2007, gallstones from 481 patients, including 68 calcium carbonate gallstones, were analyzed for total calcium content. Gallbladder bile samples from 33 cases and six controls were analyzed for pH, carbonate anion level, free-ionized calcium concentration and saturation index for calcium carbonate. Total calcium content averaged 75.6 %, 11.8 %, and 4.2 % for calcium carbonate, calcium bilirubinate and cholesterol gallstones. In 29.4 % of patients, chronic and/or intermittent cystic duct obstructions were caused by polypoid lesions in the neck region and 70.6 % were caused by stones. A total of 82 % of patients had chronic low-grade inflammation of the gallbladder wall and 18.0 % had acute inflammatory exacerbations. In the bile, we found the mean pH, mean carbonate anion, free-ionized calcium concentrations, and mean saturation index for calcium carbonate to be elevated in comparison to controls. From our study, we found chronic and/or intermittent cystic duct obstructions and low-grade GB wall inflammation lead to GB epithelium hydrogen secretion dysfunction. Increased calcium ion efflux into the GB lumen combined with increased carbonate anion presence increases SI_CaCO(3) from 1 to 22.4. Thus, in an alkaline milieu with pH 7.8, calcium carbonate begins to aggregate and precipitate. Copyright © 2012. Published by Elsevier B.V.

  12. Effect of calcium intake on urinary oxalate excretion in calcium stone-forming patients

    Directory of Open Access Journals (Sweden)

    Nishiura J.L.

    2002-01-01

    Full Text Available Dietary calcium lowers the risk of nephrolithiasis due to a decreased absorption of dietary oxalate that is bound by intestinal calcium. The aim of the present study was to evaluate oxaluria in normocalciuric and hypercalciuric lithiasic patients under different calcium intake. Fifty patients (26 females and 24 males, 41 ± 10 years old, whose 4-day dietary records revealed a regular low calcium intake (<=500 mg/day, received an oral calcium load (1 g/day for 7 days. A 24-h urine was obtained before and after load and according to the calciuria under both diets, patients were considered as normocalciuric (NC, N = 15, diet-dependent hypercalciuric (DDHC, N = 9 or diet-independent hypercalciuric (DIHC, N = 26. On regular diet, mean oxaluria was 30 ± 14 mg/24 h for all patients. The 7-day calcium load induced a significant decrease in mean oxaluria compared to the regular diet in NC and DIHC (20 ± 12 vs 26 ± 7 and 27 ± 18 vs 32 ± 15 mg/24 h, respectively, P<0.05 but not in DDHC patients (22 ± 10 vs 23 ± 5 mg/24 h. The lack of an oxalate decrease among DDHC patients after the calcium load might have been due to higher calcium absorption under higher calcium supply, with a consequent lower amount of calcium left in the intestine to bind with oxalate. These data suggest that a long-lasting regular calcium consumption <500 mg was not associated with high oxaluria and that a subpopulation of hypercalciuric patients who presented a higher intestinal calcium absorption (DDHC tended to hyperabsorb oxalate as well, so that oxaluria did not change under different calcium intake.

  13. NA48 prototype calorimeter

    CERN Multimedia

    1990-01-01

    This is a calorimeter, a detector which measures the energy of particles. When in use, it is filled with liquid krypton at -152°C. Electrons and photons passing through interact with the krypton, creating a shower of charged particles which are collected on the copper ribbons. The ribbons are aligned to an accuracy of a tenth of a millimetre. The folding at each end allows them to be kept absolutely flat. Each shower of particles also creates a signal in scintillating material embedded in the support disks. These flashes of light are transmitted to electronics by the optical fibres along the side of the detector. They give the time at which the interaction occurred. The photo shows the calorimeter at NA48, a CERN experiment which is trying to understand the lack of anti-matter in the Universe today.

  14. Protein-Mediated Precipitation of Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    Izabela Polowczyk

    2016-11-01

    Full Text Available Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, and Fourier transform infrared spectroscopy (FTIR measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO3 particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO3 formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein.

  15. Protein-Mediated Precipitation of Calcium Carbonate

    Science.gov (United States)

    Polowczyk, Izabela; Bastrzyk, Anna; Fiedot, Marta

    2016-01-01

    Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO3 particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO3 formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein. PMID:28774065

  16. Evidence of a Lead Metathesis Product from Calcium Hydroxyapatite Dissolution in Lead Nitrate Solution

    Directory of Open Access Journals (Sweden)

    Oratai Saisa-ard

    2014-01-01

    Full Text Available Calcium hydroxyapatite, CaHAp, synthesized by the precipitation method, was utilized to study the calcium-lead metathesis reaction on dissolution in a lead nitrate solution under reflux conditions to prepare larger lead hydroxyapatite, PbHAp, crystals from CaHAp. SEM images show development of crystalline PbHAp on the surfaces of CaHAp. The needle-like crystal morphology observed for PbHAp after 24 h reaction time developed into hexagonal-rod crystal morphology within 48 h reaction time. The largest PbHAp crystals obtained from 48 h reaction time have approximate size of 10 × 10 × 40 μm. Powder X-ray diffraction results show mixed phases of CaHAp and PbHAp due to difficulty in separating the PbHAp product from the CaHAp substrate. The PbHAp peaks observed after 24 h of reaction sharpen and increase in intensity after 48 h of reaction confirming that the PbHAp phase is the major product for the 48 h reaction time. EDX results of the crystalline products show high intensity Pb peaks with lead to phosphorous ratio (5 : 3 as expected for PbHAp. Lower intensity Ca peaks are also observed, consistent with incomplete coverage of the CaHAp growth substrate.

  17. Calcium Signaling Is Required for Erythroid Enucleation.

    Directory of Open Access Journals (Sweden)

    Christina B Wölwer

    Full Text Available Although erythroid enucleation, the property of erythroblasts to expel their nucleus, has been known for 7ore than a century, surprisingly little is known regarding the molecular mechanisms governing this unique developmental process. Here we show that similar to cytokinesis, nuclear extrusion requires intracellular calcium signaling and signal transduction through the calmodulin (CaM pathway. However, in contrast to cytokinesis we found that orthochromatic erythroblasts require uptake of extracellular calcium to enucleate. Together these functional studies highlight a critical role for calcium signaling in the regulation of erythroid enucleation.

  18. Coronary artery calcium score: current status

    Science.gov (United States)

    Neves, Priscilla Ornellas; Andrade, Joalbo; Monção, Henry

    2017-01-01

    The coronary artery calcium score plays an Important role In cardiovascular risk stratification, showing a significant association with the medium- or long-term occurrence of major cardiovascular events. Here, we discuss the following: protocols for the acquisition and quantification of the coronary artery calcium score by multidetector computed tomography; the role of the coronary artery calcium score in coronary risk stratification and its comparison with other clinical scores; its indications, interpretation, and prognosis in asymptomatic patients; and its use in patients who are symptomatic or have diabetes. PMID:28670030

  19. Feasibility of coronary calcium and stent image subtraction using 320-detector row CT angiography

    DEFF Research Database (Denmark)

    Fuchs, Andreas; Kühl, J Tobias; Chen, Marcus Y

    2015-01-01

    . The use of coronary calcium image subtraction improved the reader confidence in 66% of these segments. In target segments, specificity (86% vs 65%; P positive predictive value (71% vs 51%, P = .03) were improved using CCTAsub compared to CCTAconv without loss in negative predictive value....... We defined target segments on CCTAconv as motion-free coronary segments with calcification or stent and low reader confidence. The effect of CCTAsub was assessed. No approval from the ethics committee was required according to Danish law. RESULTS: A total of 76 target segments were identified...... severity leading to false-positive results. In a pilot study, we tested the feasibility of a new coronary calcium image subtraction algorithm in relation to reader confidence and diagnostic accuracy. METHODS: Forty-three patients underwent clinically indicated ICA and CCTA using a 320-detector row CT...

  20. A randomized, double-blind, placebo-controlled, clinical study on the efficacy and safety of calcium dobesilate in the treatment of chronic venous insufficiency.

    Science.gov (United States)

    Rabe, Eberhard; Ballarini, Stefania; Lehr, Lorenz

    2016-05-01

    To show the superiority of 500 mg calcium dobesilate vs. placebo in reduction of edema of the lower limbs in patients with chronic venous insufficiency, Clinical, Etiological, Anatomical and Pathophysiological classes C3/C4. A total of 351 patients were randomized (n = 174 calcium dobesilate, n = 177 placebo). Active treatment was 500 mg calcium dobesilate, three times daily for 12 weeks, with a 12-week follow-up. At the end of treatment, the relative volume change in the most pathological leg was -0.6 ± 4.8% with calcium dobesilate compared to -0.3 ± 3.3% with placebo (p = 0.09). At the end of follow-up, this was -1.01 ± 5.4% for calcium dobesilate vs. -0.08 ± 3.5% for placebo (p = 0.002). Calcium dobesilate treatment resulted in no significant volume change in the most pathological leg between baseline and end of treatment. However, the calcium dobesilate group showed a significantly greater volume decrease in the most pathological leg at the end of follow-up. Calcium dobesilate was well-tolerated, with a safety profile consistent with previously published data. © The Author(s) 2015.

  1. Delay in onset of metabolic alkalosis during regional citrate anti-coagulation in continous renal replacement therapy with calcium-free replacement solution

    Directory of Open Access Journals (Sweden)

    See Kay

    2009-01-01

    Full Text Available Regional citrate anti-coagulation for continuous renal replacement therapy chelates calcium to produce the anti- coagulation effect. We hypothesise that a calcium-free replacement solution will require less citrate and produce fewer metabolic side effects. Fifty patients, in a Medical Intensive Care Unit of a tertiary teaching hospital (25 in each group, received continuous venovenous hemofiltration using either calcium-containing or calcium-free replacement solutions. Both groups had no significant differences in filter life, metabolic alkalosis, hypernatremia, hypocalcemia, and hypercalcemia. However, patients using calcium-containing solution developed metabolic alkalosis earlier, compared to patients using calcium-free solution (mean 24.6 hours,CI 0.8-48.4 vs. 37.2 hours, CI 9.4-65, P = 0.020. When calcium-containing replacement solution was used, more citrate was required (mean 280ml/h, CI 227.2-332.8 vs. 265ml/h, CI 203.4-326.6, P = 0.069, but less calcium was infused (mean 21.2 ml/h, CI 1.2-21.2 vs 51.6ml/h, CI 26.8-76.4, P ≤ 0.0001.

  2. STIM and calcium channel complexes in cancer.

    Science.gov (United States)

    Jardin, Isaac; Rosado, Juan A

    2016-06-01

    The ion Ca(2+) is a ubiquitous second messenger that mediates a variety of cellular functions. Dysfunction of the mechanisms involved in Ca(2+) homeostasis underlies a number of pathological processes, including cancer. Store-operated Ca(2+) entry (SOCE) is a major mechanism for Ca(2+) entry modulated by the intracellular Ca(2+) stores. The Ca(2+)-selective store-operated current (ICRAC) is mediated by the endoplasmic reticulum (ER) Ca(2+) sensor STIM1 and the store-operated Ca(2+) (SOC) channel Orai1, while other non-selective cation currents (ISOC) involves the participation of members of the canonical transient receptor potential (TRPC) channel family, including TRPC1. Distinct isoforms of the key components of SOCE have been described in mammalian cells, STIM1 and 2, Orai1-3 and TRPC1-7. In cancer cells, SOCE has been reported to play an important role in cell cycle progression and proliferation, migration, metastasis and evasion of apoptosis. Changes in the expression of the key elements of SOCE and Ca(2+) homeostasis remodeling have been account to play important roles in the phenotypic changes observed in transformed cells. Despite there are differences in the expression level of the molecular components of SOCE, as well as in the relevance of the STIM, Orai and TRPC isoforms in SOCE and tumorigenesis among cancer cell types, there is a body of evidence supporting an important role for SOCE underlying the phenotypic modifications of cancer cells that propose STIM and the SOC channels as suitable candidate targets for future prognostic or therapeutic strategies. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Calcium wave signaling in cancer cells

    Science.gov (United States)

    PARKASH, JAI; ASOTRA, KAMLESH

    2010-01-01

    Ca2+ functions as an important signaling messenger right from beginning of the life to final moment of the end of the life. Ca2+ is needed at several steps of the cell cycle such as early G1, at the G1/S, and G2/M transitions. The Ca2+ signals in the form of time-dependent changes in intracellular Ca2+ concentrations, [Ca2+]i, are presented as brief spikes organized into regenerative Ca2+ waves. Ca2+-mediated signaling pathways have also been shown to play important roles in carcinogenesis such as transformation of normal cells to cancerous cells, tumor formation and growth, invasion, angiogenesis and metastasis. Since the global Ca2+ oscillations arise from Ca2+ waves initiated locally, it results in stochastic oscillations because although each cell has many IP3Rs and Ca2+ ions, the law of large numbers does not apply to the initiating event which is restricted to very few IP3Rs due to steep Ca2+ concentration gradients. The specific Ca2+ signaling information is likely to be encoded in a calcium code as the amplitude, duration, frequency, waveform or timing of Ca2+ oscillations and decoded again at a later stage. Since Ca2+ channels or pumps involved in regulating Ca2+ signaling pathways show altered expression in cancer, one can target these Ca2+ channels and pumps as therapeutic options to decrease proliferation of cancer cells and to promote their apoptosis. These studies can provide novel insights into alterations in Ca2+ wave patterns in carcinogenesis and lead to development of newer technologies based on Ca2+ waves for the diagnosis and therapy of cancer. PMID:20875431

  4. An In Vitro Comparative Study on the Antimicrobial Effects of Bioglass 45S5 vs. Calcium Hydroxide on Enterococcus Faecalis.

    Science.gov (United States)

    Mehrvarzfar, Payman; Akhavan, Hengameh; Rastgarian, Hossein; Mohammadzade Akhlagi, Nahid; Soleymanpour, Reza; Ahmadi, Anahid

    2011-01-01

    An ideal intracanal medicament should be able to eliminate any remaining intracanal microorganism. The aim of this study was to compare the antimicrobial effects of Bioglass 45S5 with calcium hydroxide on Enterococcus (E) faecalis in-vitro. Direct exposure test (DET) was used to evaluate the antimicrobial effect of Bioglass 45S5, calcium hydroxide and normal saline (control group) on 80 paper cones contaminated with E. faecalis suspension. All samples were aseptically transferred into BHI culture medium to quantify microbial concentration in periods of 1, 24, 48 and 72 hours. Turbidity of the culture medium was measured via optical density (OPD) method with a spectrophotometer (wavelength=540nm). Results were then analysed statistically using student t-test. Mean difference of optical density between Bioglass 45S5 and calcium hydroxide appeared insignificant within 1 hour of the test period (P>0.05); however calcium hydroxide showed significantly greater antimicrobial properties after 24 hours (PBioglass 45S5 and calcium hydroxide exhibited antimicrobial effects against E. faecalis, neither attained complete eradication of bacteria. However, calcium hydroxide seemed to have superior disinfecting effect.

  5. Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate

    Directory of Open Access Journals (Sweden)

    Clovis Monteiro BRAMANTE

    2013-01-01

    Full Text Available Objective To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. Material and Methods Twenty-four mice (Rattus norvegicus received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. Results Histologic observation showed no statistically significant difference of biocompatibility (p>0.05 among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s, followed by clinker with 2% calcium sulfate (9.22 s/25.33 s, clinker with 5% calcium sulfate (10.06 s/42.46 s and MTA (15.01 s/42.46 s. Conclusions All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinker.

  6. Structures of apicomplexan calcium-dependent protein kinases reveal mechanism of activation by calcium

    Energy Technology Data Exchange (ETDEWEB)

    Wernimont, Amy K; Artz, Jennifer D.; Jr, Patrick Finerty; Lin, Yu-Hui; Amani, Mehrnaz; Allali-Hassani, Abdellah; Senisterra, Guillermo; Vedadi, Masoud; Tempel, Wolfram; Mackenzie, Farrell; Chau, Irene; Lourido, Sebastian; Sibley, L. David; Hui, Raymond (Toronto); (WU-MED)

    2010-09-21

    Calcium-dependent protein kinases (CDPKs) have pivotal roles in the calcium-signaling pathway in plants, ciliates and apicomplexan parasites and comprise a calmodulin-dependent kinase (CaMK)-like kinase domain regulated by a calcium-binding domain in the C terminus. To understand this intramolecular mechanism of activation, we solved the structures of the autoinhibited (apo) and activated (calcium-bound) conformations of CDPKs from the apicomplexan parasites Toxoplasma gondii and Cryptosporidium parvum. In the apo form, the C-terminal CDPK activation domain (CAD) resembles a calmodulin protein with an unexpected long helix in the N terminus that inhibits the kinase domain in the same manner as CaMKII. Calcium binding triggers the reorganization of the CAD into a highly intricate fold, leading to its relocation around the base of the kinase domain to a site remote from the substrate binding site. This large conformational change constitutes a distinct mechanism in calcium signal-transduction pathways.

  7. Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

    Science.gov (United States)

    van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

    2009-05-01

    Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

  8. Effects of Adding Chymosin to Milk on Calcium Homeostasis

    DEFF Research Database (Denmark)

    Møller, Ulla Kristine; Jensen, Lars Thorbjørn; Mosekilde, Leif

    2014-01-01

    either chymosin or similar placebo was added. Compared with placebo, chymosin did not affect 24-h urinary calcium, calcium/creatinine ratio, plasma parathyroid hormone, calcitonin or ionized calcium levels. However, during the first 4 h after intake of milk with chymosin, urinary calcium-creatinine ratio...

  9. Does calcium constrain reproductive activity in insectivorous bats ...

    African Journals Online (AJOL)

    Insects are a poor source of dietary calcium and since they are seasonally abundant, it has been suggested that calcium availability may play a significant role in controlling the timing of reproduction in insectivorous bats. To assess the possible role of dietary calcium, we have measured bone calcium concentrations in ...

  10. Model of intracellular calcium cycling in ventricular myocytes.

    Science.gov (United States)

    Shiferaw, Y; Watanabe, M A; Garfinkel, A; Weiss, J N; Karma, A

    2003-12-01

    We present a mathematical model of calcium cycling that takes into account the spatially localized nature of release events that correspond to experimentally observed calcium sparks. This model naturally incorporates graded release by making the rate at which calcium sparks are recruited proportional to the whole cell L-type calcium current, with the total release of calcium from the sarcoplasmic reticulum (SR) being just the sum of local releases. The dynamics of calcium cycling is studied by pacing the model with a clamped action potential waveform. Experimentally observed calcium alternans are obtained at high pacing rates. The results show that the underlying mechanism for this phenomenon is a steep nonlinear dependence of the calcium released from the SR on the diastolic SR calcium concentration (SR load) and/or the diastolic calcium level in the cytosol, where the dependence on diastolic calcium is due to calcium-induced inactivation of the L-type calcium current. In addition, the results reveal that the calcium dynamics can become chaotic even though the voltage pacing is periodic. We reduce the equations of the model to a two-dimensional discrete map that relates the SR and cytosolic concentrations at one beat and the previous beat. From this map, we obtain a condition for the onset of calcium alternans in terms of the slopes of the release-versus-SR load and release-versus-diastolic-calcium curves. From an analysis of this map, we also obtain an understanding of the origin of chaotic dynamics.

  11. Vitamin D with calcium reduces mortality

    DEFF Research Database (Denmark)

    Rejnmark, Lars; Avenell, Alison; Masud, Tahir

    2012-01-01

    Introduction:Vitamin D may affect multiple health outcomes. If so, an effect on mortality is to be expected. Using pooled data from randomized controlled trials, we performed individual patient data (IPD) and trial level meta-analyses to assess mortality among participants randomized to either...... calcium (odds ratio, 0.94; 95% CI, 0.88-0.99), but not with vitamin D alone (odds ratio, 0.98; 95% CI, 0.91-1.06).Conclusion:Vitamin D with calcium reduces mortality in the elderly, whereas available data do not support an effect of vitamin D alone....... vitamin D alone or vitamin D with calcium.Subjects and Methods:Through a systematic literature search, we identified 24 randomized controlled trials reporting data on mortality in which vitamin D was given either alone or with calcium. From a total of 13 trials with more than 1000 participants each, eight...

  12. A Low Affinity GCaMP3 Variant (GCaMPer for Imaging the Endoplasmic Reticulum Calcium Store.

    Directory of Open Access Journals (Sweden)

    Mark J Henderson

    Full Text Available Endoplasmic reticulum calcium homeostasis is critical for cellular functions and is disrupted in diverse pathologies including neurodegeneration and cardiovascular disease. Owing to the high concentration of calcium within the ER, studying this subcellular compartment requires tools that are optimized for these conditions. To develop a single-fluorophore genetically encoded calcium indicator for this organelle, we targeted a low affinity variant of GCaMP3 to the ER lumen (GCaMPer (10.19. A set of viral vectors was constructed to express GCaMPer in human neuroblastoma cells, rat primary cortical neurons, and human induced pluripotent stem cell-derived cardiomyocytes. We observed dynamic changes in GCaMPer (10.19 fluorescence in response to pharmacologic manipulations of the ER calcium store. Additionally, periodic calcium efflux from the ER was observed during spontaneous beating of cardiomyocytes. GCaMPer (10.19 has utility in imaging ER calcium in living cells and providing insight into luminal calcium dynamics under physiologic and pathologic states.

  13. Morphological Investigation of Calcium Carbonate during Ammonification-Carbonization Process of Low Concentration Calcium Solution

    Directory of Open Access Journals (Sweden)

    Huaigang Cheng

    2014-01-01

    Full Text Available Ultrafine calcium carbonate is a widely used cheap additive. The research is conducted in low degree supersaturation solution in order to study the polymorphic phases’ change and its factors of the calcium carbonate precipitate in the ammonification-carbonization process of the solution with calcium. Fine particles of calcium carbonate are made in the solution containing 0.015 mol/L of Ca2+. Over 98% of the calcium carbonate precipitate without ammonification resembles the morphology of calcite, while the introduction of ammonia can benefit the formation of vaterite. It was inferred that the main cause should be serious partial oversaturation or steric effects. Ammonia also helps to form the twin spherical calcium carbonate. However, particles formed in the process of ammonification-carbonization in solution with low concentration degree of calcium are not even with a scale of the particle diameter from 5 to 12 μm. Inorganic salts, alcohol, or organic acid salts have significant controlling effect on the particle diameter of calcium carbonate and can help to decrease the particle diameter to about 3 μm. Anionic surfactants can prevent the conglobation of calcium carbonate particles and shrink its diameter to 500 nm–1 μm.

  14. Fractal aspects of calcium binding protein structures

    Energy Technology Data Exchange (ETDEWEB)

    Isvoran, Adriana [West University of Timisoara, Department of Chemistry, Pestalozzi 16, 300115 Timisoara (Romania)], E-mail: aisvoran@cbg.uvt.ro; Pitulice, Laura [West University of Timisoara, Department of Chemistry, Pestalozzi 16, 300115 Timisoara (Romania); Craescu, Constantin T. [INSERM U759/Institute Curie-Recherche, Centre Universitaire Paris-Sud, Batiment 112, 91405 Orsay (France); Chiriac, Adrian [West University of Timisoara, Department of Chemistry, Pestalozzi 16, 300115 Timisoara (Romania)

    2008-03-15

    The structures of EF-hand calcium binding proteins may be classified into two distinct groups: extended and compact structures. In this paper we studied 20 different structures of calcium binding proteins using the fractal analysis. Nine structures show extended shapes, one is semi-compact and the other 10 have compact shapes. Our study reveals different fractal characteristics for protein backbones belonging to different structural classes and these observations may be correlated to the physicochemical forces governing the protein folding.

  15. Understanding calcium dynamics experiments and theory

    CERN Document Server

    Malchow, Dieter

    2003-01-01

    Intracellular Calcium is an important messenger in living cells. Calcium dynamics display complex temporal and spatial structures created by the concentration patterns which are characteristic for a nonlinear system operating far from thermodynamic equilibrium. Written as a set of tutorial reviews on both experimental facts and theoretical modelling, this volume is intended as an introduction and modern reference in the field for graduate students and researchers in biophysics, biochemistry and applied mathematics.

  16. Analytical models of calcium binding in a calcium channel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinn-Liang [Department of Applied Mathematics, National Hsinchu University of Education, Hsinchu 300, Taiwan (China); Eisenberg, Bob [Department of Molecular Biophysics and Physiology, Rush University, Chicago, Illinois 60612 (United States)

    2014-08-21

    The anomalous mole fraction effect of L-type calcium channels is analyzed using a Fermi like distribution with the experimental data of Almers and McCleskey [J. Physiol. 353, 585 (1984)] and the atomic resolution model of Lipkind and Fozzard [Biochemistry 40, 6786 (2001)] of the selectivity filter of the channel. Much of the analysis is algebraic, independent of differential equations. The Fermi distribution is derived from the configuration entropy of ions and water molecules with different sizes, different valences, and interstitial voids between particles. It allows us to calculate potentials and distances (between the binding ion and the oxygen ions of the glutamate side chains) directly from the experimental data using algebraic formulas. The spatial resolution of these results is comparable with those of molecular models, but of course the accuracy is no better than that implied by the experimental data. The glutamate side chains in our model are flexible enough to accommodate different types of binding ions in different bath conditions. The binding curves of Na{sup +} and Ca{sup 2+} for [CaCl{sub 2}] ranging from 10{sup −8} to 10{sup −2} M with a fixed 32 mM background [NaCl] are shown to agree with published Monte Carlo simulations. The Poisson-Fermi differential equation—that includes both steric and correlation effects—is then used to obtain the spatial profiles of energy, concentration, and dielectric coefficient from the solvent region to the filter. The energy profiles of ions are shown to depend sensitively on the steric energy that is not taken into account in the classical rate theory. We improve the rate theory by introducing a steric energy that lumps the effects of excluded volumes of all ions and water molecules and empty spaces between particles created by Lennard-Jones type and electrostatic forces. We show that the energy landscape varies significantly with bath concentrations. The energy landscape is not constant.

  17. Contribution of calcium oxalate to soil-exchangeable calcium

    Science.gov (United States)

    Dauer, Jenny M.; Perakis, Steven S.

    2013-01-01

    Acid deposition and repeated biomass harvest have decreased soil calcium (Ca) availability in many temperate forests worldwide, yet existing methods for assessing available soil Ca do not fully characterize soil Ca forms. To account for discrepancies in ecosystem Ca budgets, it has been hypothesized that the highly insoluble biomineral Ca oxalate might represent an additional soil Ca pool that is not detected in standard measures of soil-exchangeable Ca. We asked whether several standard method extractants for soil-exchangeable Ca could also access Ca held in Ca oxalate crystals using spike recovery tests in both pure solutions and soil extractions. In solutions of the extractants ammonium chloride, ammonium acetate, and barium chloride, we observed 2% to 104% dissolution of Ca oxalate crystals, with dissolution increasing with both solution molarity and ionic potential of cation extractant. In spike recovery tests using a low-Ca soil, we estimate that 1 M ammonium acetate extraction dissolved sufficient Ca oxalate to contribute an additional 52% to standard measurements of soil-exchangeable Ca. However, in a high-Ca soil, the amount of Ca oxalate spike that would dissolve in 1 M ammonium acetate extraction was difficult to detect against the large pool of exchangeable Ca. We conclude that Ca oxalate can contribute substantially to standard estimates of soil-exchangeable Ca in acid forest soils with low soil-exchangeable Ca. Consequently, measures of exchangeable Ca are unlikely to fully resolve discrepancies in ecosystem Ca mass balance unless the contribution of Ca oxalate to exchangeable Ca is also assessed.

  18. Calcium burden assessment and impact on drug-eluting balloons in peripheral arterial disease.

    Science.gov (United States)

    Fanelli, F; Cannavale, A; Gazzetti, M; Lucatelli, P; Wlderk, A; Cirelli, C; d'Adamo, A; Salvatori, F M

    2014-08-01

    This study was designed to assess the effect of calcium on the efficacy of DEB during revascularization of steno-obstructive SFA lesions. Sixty patients with de novo lesions of the superficial femoral artery underwent endovascular treatment with drug eluting balloons (DEB). DEB was selected according to vessel reference diameter (1:1). In case of residual stenosis > 50 % or flow-limiting dissection, postdilatation with conventional balloon or provisional stenting was done. Patients were classified into eight groups according to circumferential distribution of calcium on CT-angiography axial images (from 0° to 360°) and to its length (length  3 cm) evaluated with digital-subtraction-angiography. Ankle-brachial index (ABI), late lumen loss (LLL), target lesion revascularization (TLR), primary (PP) and secondary (SP) patency, major adverse events (MAE), and Rutherford shift were evaluated at 1-year follow-up and correlated with the amount of calcium. Revascularization was successful in all cases. Flow-limiting dissection occurred in five cases (8.3 %) with a higher circumferential degree of calcium and solved in three cases with postdilatation and in the other two with provisional stenting. DEB effect was lower in patients with higher degree of calcium (>270° vs. <90°): ABI 0.71 ± 0.07 versus 0.92 ± 0.07; LLL 0.75 ± 0.21 versus 0.45 ± 0.1; PP 50 versus 100 %; SP 50 versus 100 %; TLR 25 versus 0 %; MAE 25 versus 0 %. Calcium represents a barrier to optimal drug absorption. Circumferential distribution seems to be the most influencing factor with the worst effect noticed in 360° calcium presence.

  19. Calcium intake and colorectal cancer risk: dose-response meta-analysis of prospective observational studies.

    Science.gov (United States)

    Keum, NaNa; Aune, Dagfinn; Greenwood, Darren C; Ju, Woong; Giovannucci, Edward L

    2014-10-15

    Mechanistic and epidemiologic studies provide considerable evidence for a protective association between calcium intake and incident colorectal cancer (CRC). While the relationship has not been substantiated by short-duration randomized controlled trials (RCTs) of CRC, trials do show a benefit on adenomas, a precursor to CRC. To address some of this inconsistency, we conducted dose-response meta-analyses by sources of calcium intake, based on prospective observational studies published up to December 2013 identified from PubMed, Embase, and BIOSIS. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random-effects model. For total calcium intake, each 300 mg/day increase was associated with an approximately 8% reduced risk of CRC (summary RR = 0.92, 95% CI = 0.89-0.95, I(2)  = 47%, 15 studies with 12,305 cases, intake = 250-1,900 mg/day, follow-up = 3.3-16 years). While the risk decreased less steeply in higher range of total calcium intake (P(non-linearity)  = 0.04), the degree of curvature was mild and statistical significance of non-linearity was sensitive to one study. For supplementary calcium, each 300 mg/day increase was associated with an approximately 9% reduced risk of CRC (summary RR = 0.91, 95% CI = 0.86-0.98, I(2)  = 67%, six studies with 8,839 cases, intake = 0-1,150 mg/day, follow-up = 5-10 years). The test for non-linearity was not statistically significant (P(non-linearity)  = 0.11). In conclusion, both dietary and supplementary calcium intake may continue to decrease CRC risk beyond 1,000 mg/day. Calcium supplements and non-dairy products fortified with calcium may serve as additional targets in the prevention of CRC. RCTs of calcium supplements with at least 10 years of follow-up are warranted to confirm a benefit of calcium supplements on CRC risk. © 2014 UICC.

  20. Self-Setting Calcium Orthophosphate Formulations

    Science.gov (United States)

    Dorozhkin, Sergey V.

    2013-01-01

    In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided. PMID:24956191

  1. Calcium signaling in human pluripotent stem cells.

    Science.gov (United States)

    Apáti, Ágota; Berecz, Tünde; Sarkadi, Balázs

    2016-03-01

    Human pluripotent stem cells provide new tools for developmental and pharmacological studies as well as for regenerative medicine applications. Calcium homeostasis and ligand-dependent calcium signaling are key components of major cellular responses, including cell proliferation, differentiation or apoptosis. Interestingly, these phenomena have not been characterized in detail as yet in pluripotent human cell sates. Here we review the methods applicable for studying both short- and long-term calcium responses, focusing on the expression of fluorescent calcium indicator proteins and imaging methods as applied in pluripotent human stem cells. We discuss the potential regulatory pathways involving calcium responses in hPS cells and compare these to the implicated pathways in mouse PS cells. A recent development in the stem cell field is the recognition of so called "naïve" states, resembling the earliest potential forms of stem cells during development, as well as the "fuzzy" stem cells, which may be alternative forms of pluripotent cell types, therefore we also discuss the potential role of calcium homeostasis in these PS cell types. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Achievement of NKF/K-DOQI recommended target values for bone and mineral metabolism in incident hemodialysis patients: results of the FARO-2 cohort.

    Science.gov (United States)

    Cozzolino, Mario; Messa, Piergiorgio; Brancaccio, Diego; Cannella, Giuseppe; Bolasco, Piergiorgio; Di Luca, Marina; Costanzo, Anna Maria; Paparatti, Umberto di Luzio; Festa, Vincenzo; Gualberti, Giuliana; Mazzaferro, Sandro

    2014-01-01

    Mineral Bone Disorders (MBD) is prevalent in hemodialysis (HD) patients and associated with increased cardiovascular mortality. The FARO-2 study evaluated the achievement of the NKF/K-DOQI guidelines on recommended target values for serum calcium (Ca), phosphorous (P) and intact parathyroid hormone (PTH) levels on survival in incident HD patients. Data were collected by questionnaire from 568 incident HD patients followed prospectively over a 3-year period from 26 Italian dialysis units. The cumulative probability of time-to-death for CKD-MBD treatment characteristics was determined by the Kaplan-Meier curves. Serum PTH levels (median values at 6 months vs. 36 months; 225 vs. 254 pg/ml), Ca (8.8 vs. 8.9 g/dl) and P (5.1 vs. 4.8 mg/dl) were not significantly different at 6 months versus follow-up. The majority of incident HD patients (60-70%) who were followed up for 36 months did not achieve the NKF/K-DOQI recommended target values. Survival rates were higher in patients on target for three parameters versus patients off target (survival at 24 months: at target 95.7% (95% CI: 84.0-98.9) versus not on target 71.1% (95% CI: 66.3-75.4, p < 0.01)). The 30.1% of patients on target for three MBD parameters at least once during the follow-up period had better survival rates compared to those not reaching these targets (survival at 24 months: at least once 88.0% (95% CI: 81.9-92.1); 67.7% (95% CI: 61.9-72.8, p < 0.01)). Our findings indicate that incident HD patients who achieved target levels (for three MBD parameters) for at least one visit have a lower risk of mortality. © 2014 S. Karger AG, Basel.

  3. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity

    NARCIS (Netherlands)

    Cornelisse, L.N.; van Elburg, R.A.J.; Meredith, R.M.; Yuste, R.; Mansvelder, H.D.

    2007-01-01

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action

  4. High Speed Two-Photon Imaging of Calcium Dynamics in Dendritic Spines: : Consequences for Spine Calcium Kinetics and Buffer Capacity

    NARCIS (Netherlands)

    van Elburg, R.A.J.; Cornelisse, L.N; Meredith, R.M; Yuste, R; Mansvelder, H.D

    2007-01-01

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action

  5. Oral calcium carbonate affects calcium but not phosphorus balance in stage 3-4 chronic kidney disease.

    Science.gov (United States)

    Hill, Kathleen M; Martin, Berdine R; Wastney, Meryl E; McCabe, George P; Moe, Sharon M; Weaver, Connie M; Peacock, Munro

    2013-05-01

    Patients with chronic kidney disease (CKD) are given calcium carbonate to bind dietary phosphorus, reduce phosphorus retention, and prevent negative calcium balance; however, data are limited on calcium and phosphorus balance during CKD to support this. Here, we studied eight patients with stage 3 or 4 CKD (mean estimated glomerular filtration rate 36 ml/min) who received a controlled diet with or without a calcium carbonate supplement (1500 mg/day calcium) during two 3-week balance periods in a randomized placebo-controlled cross-over design. All feces and urine were collected during weeks 2 and 3 of each balance period and fasting blood, and urine was collected at baseline and at the end of each week. Calcium kinetics were determined using oral and intravenous (45)calcium. Patients were found to be in neutral calcium and phosphorus balance while on the placebo. Calcium carbonate supplementation produced positive calcium balance, did not affect phosphorus balance, and produced only a modest reduction in urine phosphorus excretion compared with placebo. Calcium kinetics demonstrated positive net bone balance but less than overall calcium balance, suggesting soft-tissue deposition. Fasting blood and urine biochemistries of calcium and phosphate homeostasis were unaffected by calcium carbonate. Thus, the positive calcium balance produced by calcium carbonate treatment within 3 weeks cautions against its use as a phosphate binder in patients with stage 3 or 4 CKD, if these findings can be extrapolated to long-term therapy.

  6. Scrophularia orientalis extract induces calcium signaling and apoptosis in neuroblastoma cells

    Science.gov (United States)

    LANGE, INGO; MOSCHNY, JULIA; TAMANYAN, KAMILLA; KHUTSISHVILI, MANANA; ATHA, DANIEL; BORRIS, ROBERT P.; KOOMOA, DANA-LYNN

    2016-01-01

    Effective neuroblastoma (NB) treatments are still limited despite treatment options available today. Therefore, this study attempted to identify novel plant extracts that have anticancer effects. Cytotoxicity and increased intracellular calcium levels were determined using the Sulforhodamine B (SRB) assay and Fluo4-AM (acetoxymethyl) staining and fluorescence microscopy in NB cells in order to screen a library of plant extracts. The current study examined the anticancer effects of a dichloromethane extract from Scrophularia orientalis L. (Scrophulariaceae), a plant that has been used in Traditional Chinese Medicine. This extract contained highly potent agents that significantly reduced cell survival and increased calcium levels in NB cells. Further analysis revealed that cell death induced by this extract was associated with intracellular calcium release, opening of the MPTP, caspase 3- and PARP-cleavage suggesting that this extract induced aberrant calcium signaling that resulted in apoptosis via the mitochondrial pathway. Therefore, agents from Scrophularia orientalis may have the potential to lead to new chemo therapeutic anticancer drugs. Furthermore, targeting intracellular calcium signaling may be a novel strategy to develop more effective treatments for NB. PMID:26848085

  7. The influence of environmental calcium concentrations on calcium flux, compensatory drinking and epithelial calcium channel expression in a freshwater cartilaginous fish.

    Science.gov (United States)

    Allen, Peter J; Weihrauch, Dirk; Grandmaison, Vanessa; Dasiewicz, Patricia; Peake, Stephan J; Anderson, W Gary

    2011-03-15

    Calcium metabolism and mRNA levels of the epithelial calcium channel (ECaC) were examined in a freshwater cartilaginous fish, the lake sturgeon Acipenser fulvescens. Lake sturgeon were acclimated for ≥2 weeks to 0.1 (low), 0.4 (normal) or 3.3 (high) mmol l(-1) environmental calcium. Whole-body calcium flux was examined using (45)Ca as a radioactive marker. Net calcium flux was inward in all treatment groups; however, calcium influx was greatest in the low calcium environment and lowest in the high calcium environment, whereas efflux had the opposite relationship. A significant difference in the concentration of (45)Ca in the gastrointestinal tract (GIT) of fish in the low calcium environment led to the examination of drinking rate and calcium flux across the anterior-middle (mid) intestine. Drinking rate was not different between treatments; however, calcium influx across the mid-intestine in the low calcium treatment was significantly greater than that in both the normal and high calcium treatments. The lake sturgeon ECaC was 2831 bp in length, with a predicted protein sequence of 683 amino acids that shared a 66% identity with the closest sequenced ECaCs from the vertebrate phyla. ECaC mRNA levels were examined in the gills, kidney, pyloric caeca, mid-intestine and spiral intestine. Expression levels were highest in the gills, then the kidneys, and were orders of magnitude lower in the GIT. Contrary to existing models for calcium uptake in the teleost gill, ECaC expression was greatest in high calcium conditions and kidney ECaC expression was lowest in low calcium conditions, suggesting that cellular transport mechanisms for calcium may be distinctly different in these freshwater cartilaginous fishes.

  8. Acute effects of calcium carbonate, calcium citrate and potassium citrate on markers of calcium and bone metabolism in young women.

    Science.gov (United States)

    Karp, Heini J; Ketola, Maarit E; Lamberg-Allardt, Christel J E

    2009-11-01

    Both K and Ca supplementation may have beneficial effects on bone through separate mechanisms. K in the form of citrate or bicarbonate affects bone by neutralising the acid load caused by a high protein intake or a low intake of alkalising foods, i.e. fruits and vegetables. Ca is known to decrease serum parathyroid hormone (S-PTH) concentration and bone resorption. We compared the effects of calcium carbonate, calcium citrate and potassium citrate on markers of Ca and bone metabolism in young women. Twelve healthy women aged 22-30 years were randomised into four controlled 24 h study sessions, each subject serving as her own control. At the beginning of each session, subjects received a single dose of calcium carbonate, calcium citrate, potassium citrate or a placebo in randomised order. The diet during each session was identical, containing 300 mg Ca. Both the calcium carbonate and calcium citrate supplement contained 1000 mg Ca; the potassium citrate supplement contained 2250 mg K. Markers of Ca and bone metabolism were followed. Potassium citrate decreased the bone resorption marker (N-terminal telopeptide of type I collagen) and increased Ca retention relative to the control session. Both Ca supplements decreased S-PTH concentration. Ca supplements also decreased bone resorption relative to the control session, but this was significant only for calcium carbonate. No differences in bone formation marker (bone-specific alkaline phosphatase) were seen among the study sessions. The results suggest that potassium citrate has a positive effect on the resorption marker despite low Ca intake. Both Ca supplements were absorbed well and decreased S-PTH efficiently.

  9. Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

    Directory of Open Access Journals (Sweden)

    Xiaohong Wang

    2014-05-01

    Full Text Available Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA. Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications.

  10. Increase of a Calcium Independent Transglutaminase Activity in the Erythrocyte during the Infection with Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Wasserman Moisés

    1999-01-01

    Full Text Available We have studied the activity of a calcium dependent transglutaminase (EC 2.3.2.13 during the growth of the parasite Plasmodium falciparum inside the infected human erythrocyte. There is only one detectable transglutaminase in the two-cell-system, and its origin is erythrocytic. No activity was detected in preparations of the parasite devoid of erythrocyte cytoplasm. The Michaelis Menten constants (Km of the enzyme for the substrates N'N'dimethylcaseine and putrescine were undistinguishable whether the cell extracts used in their determination were obtained from normal or from infected red cells. The total activity of transglutaminase in stringently synchronized cultures, measured at 0.5mM Ca2+, decreased with the maturation of the parasite. However, a fraction which became irreversibly activated and independent of calcium concentration was detected. The proportion of this fraction grew with maturation; it represented only 20% of the activity in 20 hr-old-trophozoites while in 48-hr-schizonts it was more than 85% of the total activity. The activation of this fraction of transglutaminase did not depend on an increase in the erythrocyte cytoplasmic calcium, since most of the calcium was shown to be located in the parasite.

  11. The effect of calcium supplementation on blood lead levels in Nigerian children.

    Science.gov (United States)

    Keating, Elizabeth M; Fischer, Philip R; Pettifor, John M; Pfitzner, Mark; Isichei, Christian O; Thacher, Tom D

    2011-11-01

    To determine whether calcium supplementation alters the risk of lead toxicity. Children aged 12-18 months from 3 communities in Nigeria were assigned to receive daily calcium supplementation, as either calcium carbonate (400 mg) or ground dried fish (529 ± 109 mg), or placebo. All children received 2500 IU of vitamin A. Levels of blood lead, calcium, and vitamin D metabolites were measured at baseline and after 12-18 months (n = 358). The mean (± SD) baseline lead level was 11.1 ± 7.8 μg/dL (range, 1-43 μg/dL; median, 9 μg/dL); 44.7% of subjects had a lead level >10 μg/dL. After 12-18 months, the mean lead level was 8.1 ± 6.3 μg/dL (range, 1-48 μg/dL; median, 6 μg/dL), with 22.6% with a level >10 μg/dL. Lead levels at baseline varied among communities (P = .01) and were higher in children who used eye cosmetics or lived near a lead-acid battery melter (both P affect blood lead levels. Copyright © 2011 Mosby, Inc. All rights reserved.

  12. Evaluation of calcium and folic acid supplementation in prenatal care in São Paulo

    Directory of Open Access Journals (Sweden)

    Camila Atallah Pontes da Silva

    Full Text Available CONTEXT AND OBJECTIVE: Preeclampsia and neural tube defects can be prevented during pregnancy. Today, there is level I evidence showing that calcium supplementation during pregnancy may prevent preeclampsia and that use of folic acid may prevent neural tube defects. The aim here was to evaluate the proportion of patients undergoing prenatal follow-up who had received a prescription for calcium and/or folic acid supplementation, and their adherence to the use of these two substances. DESIGN AND SETTING: Cross-sectional study at two hospitals in the Greater São Paulo region, Brazil (Faculdade de Medicina da Fundação ABC, Santo André, and "Dr. Mário de Moraes Altenfelder Silva" Municipal Teaching and Maternity Hospital, Vila Nova Cachoeirinha. METHODS: Early primigravidae, late primigravidae and pregnant women with chronic hypertension, diabetes mellitus or kidney disease who had already had their first prenatal consultation were included. RESULTS: Out of 250 pregnant women interviewed, 10.40% had received a prescription for calcium supplementation and 80.76% of them reported taking it in tablet form. Regarding folic acid, 48% of the women said that they had received a prescription for this and 64.16% reported that they had started to use it during the periconceptional period. CONCLUSIONS: Calcium supplementation and periconceptional use of folic acid seem not to be prescribed routinely by physicians. This should motivate the implementation of educational programs for obstetricians on the use of interventions based on the best available evidence.

  13. 48 CFR 1552.215-75 - Past performance information.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Past performance information. 1552.215-75 Section 1552.215-75 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION... disadvantaged business concerns, monetary targets for small disadvantaged business participation, and the...

  14. Effect of Calcium Oxide Microstructure on the Diffusion of Isotopes

    CERN Document Server

    Fernandes Ramos, João Pedro; Stora, T

    2012-01-01

    Calcium oxide (CaO) powder targets have been successfully used at CERN-ISOLDE to produce neutron deficient exotic argon and carbon isotopes under proton irradiation at high temperatures (>1000°C). These targets outperform the other related targets for the production of the same beams. However, they presented either slow release rates (yields) from the beginning or a rapid decrease over time. This problem was believed to come from the target microstructure degradation, justifying the material investigation. In order to do so, the synthesis, reactivity in ambient air and sintering kinetics of CaO were studied, through surface area determination by N2 adsorption, X-ray diffraction for crystalline phase identification and crystallite size determination, and scanning and transmission electron microscopy to investigate the microstructure. The synthesis studies revealed that a nanometric material is obtained from the decarbonation of CaCO3 in vacuum at temperatures higher than 550°C, which is very reactive in air....

  15. Coulomb excitation of {sup 48}K

    Energy Technology Data Exchange (ETDEWEB)

    Siebeck, Burkhard; Blazhev, Andrey; Geibel, Kerstin; Hess, Herbert; Reiter, Peter; Seidlitz, Michael; Schneiders, David; Steinbach, Tim; Warr, Nigel [IKP, Universitaet zu Koeln (Germany); Bauer, Christopher [IKP, TU Darmstadt (Germany); Witte, Hilde de [KU Leuven (Belgium); Klintefjord, Malin [University of Oslo (Norway); Pakarinen, Janne [University of Jyvaeskylae (Finland); Rapisarda, Elisa [KU Leuven (Belgium); CERN, Genf (Switzerland); Scheck, Marcus [University of the West of Scotland, Paisley (United Kingdom); Voulot, Didier; Wenander, Frederik [CERN, Genf (Switzerland)

    2016-07-01

    Potassium isotopes in the direct vicinity of doubly-magic nuclei are of great interest and subject of recent shell model calculations. These show that the ground states of most K isotopes are dominated by a π0p0h configuration, while {sup 47}K and {sup 49}K have a major π2p2h contribution. However, the situation is not clear for the odd-odd isotope {sup 48}K, which shows a mixture between 0p0h and 2p2h. In order to study the coupling between the νp{sub 3/2}-shell and the πs{sub 1/2}-, πd{sub 3/2}-shells, transition matrix elements are deduced from a Coulomb excitation experiment performed with MINIBALL at REX-ISOLDE. A {sup 104}Pd target was irradiated by a radioactive {sup 48}K beam. γ rays of both target and projectile deexcitation have been observed. Those yields, together with available spectroscopic data, allow the detemination of transition matrix elements with GOSIA2. The new findings are compared to shell model calculations.

  16. Inhibition of mitochondrial calcium uptake 1 in Drosophila neurons.

    Science.gov (United States)

    M'Angale, P G; Staveley, B E

    2017-02-08

    The mitochondrial calcium uptake 1 (MICU1) is a regulatory subunit of the mitochondrial calcium uniporter that plays an important role in calcium sensing. It contains two EF-hand domains that are well conserved across diverse species from protozoa to plants and metazoans. The loss of MICU1 function in mammals is attributed to several neurological disorders that involve movement dysfunction. The CG4495 gene in Drosophila melanogaster was identified as a putative homolog of MICU1 in the HomoloGene database of the National Centre for Biotechnology Information (NCBI). In agreement with previous studies that have shown the development of neurological disorders and movement defects in MICU1 loss-of-function organisms, we attempted to identify the function of CG4495/MICU1 in Drosophila neurons. We analyzed survival and locomotor ability of these flies and additionally performed biometric analysis of the Drosophila developing eye. The inducible RNA interference-mediated inhibition of CG4495/MICU1 in the Ddc-Gal4-expressing neurons of Drosophila presented with reduction in survival coupled with a precocious loss of locomotor ability. Since the pro-survival Bcl-2 family genes have been shown to be protective towards mitochondria, and CG4495/MICU1 has a mitochondrial targeting sequence, we attempted to rescue the phenotypes resulting from the inhibition of CG4495/MICU1 by overexpressing Buffy, the sole Bcl-2 homologue in Drosophila. The co-expression of CG4495/MICU1-RNAi along with Buffy resulted in the suppression of the phenotypes induced by the inhibition of CG4495/MICU1. Subsequently, the inhibition of CG4495/MICU1 in the Drosophila developing eye, a neuron-rich organ, resulted in reduced number of ommatidia and a highly fused ommatidial array. These developmental eye defects were rescued by the overexpression of Buffy. Our study suggests an important role for MICU1 in the normal function of neurons in Drosophila.

  17. The formation of calcium phosphate coatings by pulse laser deposition on the surface of polymeric ferroelectric

    Energy Technology Data Exchange (ETDEWEB)

    Bolbasov, E.N. [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation); Lapin, I.N.; Svetlichnyi, V.A. [Tomsk State University, 36 Lenin Avenue, Tomsk 634050 (Russian Federation); Lenivtseva, Y.D. [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation); Malashicheva, A. [Federal Almazov Medical Research Centre, 2 Akkuratova St., St. Petersburg 197341 (Russian Federation); St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034 (Russian Federation); ITMO University, Institute of translational Medicine, St. Petersburg (Russian Federation); Malashichev, Y. [St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034 (Russian Federation); Golovkin, A.S. [Federal Almazov Medical Research Centre, 2 Akkuratova St., St. Petersburg 197341 (Russian Federation); Anissimov, Y.G. [Griffith University, School of Natural Sciences, Engineering Dr., Southport, QLD 4222 (Australia); Tverdokhlebov, S.I., E-mail: tverd@tpu.ru [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation)

    2015-09-15

    Graphical abstract: - Highlights: • Calcium phosphate coatings were obtained on ferroelectric polymer materials surface by using PLD method. • Obtained coatings have well-developed surface. • Depending on sputtering target composition it is possible to obtain crystalline or amorphous coating. • Formation of coating does not change the crystal structure of the ferroelectric polymer material. - Abstract: This work analyses the properties of calcium phosphate coatings obtained by pulsed laser deposition on the surface of the ferroelectric polymer material. Atomic force and scanning electron microscopy studies demonstrate that, regardless of the type of sputtering target, the calcium phosphate coatings have a multiscale rough surface that is potentially capable of promoting the attachment and proliferation of osteoblasts. This developed surface of the coatings is due to its formation mainly from a liquid phase. The chemical and crystalline composition of the coatings depends on the type of sputtering target used. It was shown that, regardless of the type of sputtering target, the crystalline structure of the ferroelectric polymer material does not change. Cell viability and adhesion studies of mesenchymal stromal cells on the coatings were conducted using flow cytometry and fluorescent microscopy. These studies indicated that the produced coatings are non-toxic.

  18. Shaker and Shal mediate transient calcium-independent potassium current in a Drosophila flight motoneuron.

    Science.gov (United States)

    Ryglewski, Stefanie; Duch, Carsten

    2009-12-01

    Ionic currents underlie the firing patterns, excitability, and synaptic integration of neurons. Despite complete sequence information in multiple species, our knowledge about ion channel function in central neurons remains incomplete. This study analyzes the potassium currents of an identified Drosophila flight motoneuron, MN5, in situ. MN5 exhibits four different potassium currents, two fast-activating transient ones and two sustained ones, one of each is calcium activated. Pharmacological and genetic manipulations unravel the specific contributions of Shaker and Shal to the calcium independent transient A-type potassium currents. alpha-dendrotoxin (Shaker specific) and phrixotoxin-2 (Shal specific) block different portions of the transient calcium independent A-type potassium current. Following targeted expression of a Shaker dominant negative transgene in MN5, the remaining A-type potassium current is alpha-dendrotoxin insensitive. In Shal RNAi knock down the remaining A-type potassium current is phrixotoxin-2 insensitive. Additionally, barium blocks calcium-activated potassium currents but also a large portion of phrixotoxin-2-sensitive A-type currents. Targeted knock down of Shaker or Shal channels each cause identical reduction in total potassium current amplitude as acute application of alpha-dendrotoxin or phrixotoxin-2, respectively. This shows that the knock downs do not cause upregulation of potassium channels underlying other A-type channels during development. Immunocytochemistry and targeted expression of modified GFP-tagged Shaker channels with intact targeting sequence in MN5 indicate predominant axonal localization. These data can now be used to investigate the roles of Shaker and Shal for motoneuron intrinsic properties, synaptic integration, and spiking output during behavior by targeted genetic manipulations.

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

    Science.gov (United States)

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

    2015-10-27

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

  20. Transcriptional expression analysis of genes involved in regulation of calcium translocation and storage in finger millet (Eleusine coracana L. Gartn.).

    Science.gov (United States)

    Mirza, Neelofar; Taj, Gohar; Arora, Sandeep; Kumar, Anil

    2014-10-25

    Finger millet (Eleusine coracana) variably accumulates calcium in different tissues, due to differential expression of genes involved in uptake, translocation and accumulation of calcium. Ca(2+)/H(+) antiporter (CAX1), two pore channel (TPC1), CaM-stimulated type IIB Ca(2+) ATPase and two CaM dependent protein kinase (CaMK1 and 2) homologs were studied in finger millet. Two genotypes GP-45 and GP-1 (high and low calcium accumulating, respectively) were used to understand the role of these genes in differential calcium accumulation. For most of the genes higher expression was found in the high calcium accumulating genotype. CAX1 was strongly expressed in the late stages of spike development and could be responsible for accumulating high concentrations of calcium in seeds. TPC1 and Ca(2+) ATPase homologs recorded strong expression in the root, stem and developing spike and signify their role in calcium uptake and translocation, respectively. Calmodulin showed strong expression and a similar expression pattern to the type IIB ATPase in the developing spike only and indicating developing spike or even seed specific isoform of CaM affecting the activity of downstream target of calcium transportation. Interestingly, CaMK1 and CaMK2 had expression patterns similar to ATPase and TPC1 in various tissues raising a possibility of their respective regulation via CaM kinase. Expression pattern of 14-3-3 gene was observed to be similar to CAX1 gene in leaf and developing spike inferring a surprising possibility of CAX1 regulation through 14-3-3 protein. Our results provide a molecular insight for explaining the mechanism of calcium accumulation in finger millet. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. PTHrP regulation and calcium balance in sea bream (Sparus auratus L.) under calcium constraint

    NARCIS (Netherlands)

    Abbink, W.; Bevelander, G.S.; Hang, X.; Lu, W.; Guerreiro, P.M.; Spanings, T.; Canario, A.V.; Flik, G.

    2006-01-01

    Juvenile gilthead sea bream were exposed to diluted seawater (2.5 per thousand salinity; DSW) for 3 h or, in a second experiment, acclimated to DSW and fed a control or calcium-deficient diet for 30 days. Branchial Ca(2+) influx, drinking rate and plasma calcium levels were assessed. Sea bream

  2. Calcium spikes and calcium plateaux evoked by differential polarization in dendrites of turtle motoneurones in vitro

    DEFF Research Database (Denmark)

    Hounsgaard, J; Kiehn, O

    1993-01-01

    The ability of dendrites in turtle motoneurones to support calcium spikes and calcium plateaux was investigated using differential polarization by applied electric fields. 2. Electric fields were generated by passing current through transverse slices of the turtle spinal cord between two plate......+ spikes and Ca2+ plateaux are present in dendrites of spinal motoneurones of the turtle....

  3. Eggshell powder, a comparable or better source of calcium than purified calcium carbonate: Piglet studies

    NARCIS (Netherlands)

    Schaafsma, A.; Beelen, G.M.

    1999-01-01

    Powdered chicken eggshells might be an interesting and widely available source of calcium. In two studies using piglets we determined the digestibility of calcium from different diets. The first study compared casein-based diets with CaCO3 (CasCC) or eggshell powder (CasES). The second study

  4. Calcium response to vitamin D supplementation

    Directory of Open Access Journals (Sweden)

    Francisco R. Spivacow

    2018-01-01

    Full Text Available Several studies show the importance of serum vitamin D sufficient levels to prevent multiple chronic diseases. However, vitamin D supplementation and its effects on urine calcium excretion remain controversial. The objective of this prospective and interventional study was to evaluate urine calcium excretion in women with normal calciuria or hypercalciuria, once serum vitamin D sufficiency was achieved. We studied 63 women with idiopathic hypercalciuria, (9 with renal lithiasis and 50 normocalciuric women. Both groups had serum vitamin D levels low (deficiency or insufficiency. Baseline urine calcium excretion was measured before being supplemented with vitamin D2 or D3 weekly or vitamin D3 100.000 IU monthly. Once serum vitamin D levels were corrected achieving at least 30 ng/ml, a second urine calcium excretion was obtained. Although in the whole sample we did not observe significant changes in urine calcium excretion according to the way of supplementation, some of those with weekly supplementation had significant higher urine calcium excretion, 19% (n = 12 of hypercalciuric women and 12% (n = 6 of the normocalciuric group. Monthly doses, also showed higher urine calcium excretion in 40% of hypercalciuric women (n = 4/10 and in 44% (n = 4/9 of the renal lithiasis hypercalciuric patients. In conclusion, different ways of vitamin D supplementation and adequate serum levels are safe in most patients, although it should be taken into account a subgroup, mainly with monthly loading doses, that could increase the calciuria significantly eventually rising renal lithiasis risk or bone mass loss, if genetically predisposed.

  5. [Raynaud's phenomenon and calcium blocking agents. A preliminary open study with flunarizine].

    Science.gov (United States)

    Centonze, V; Campanale, G; Vino, M; Caporaletti, P; Magrone, D; Russo, P; Di Bari, M; Loragno, V; Albano, O

    1991-04-30

    Raynaud's phenomenon (Raynaud's disease), an accessual vascular acrosyndrome characterised by an important constriction of distal arterioles, has still no specific pharmacological therapy. In the last years, the use of calcium-entry-blockers (nifedipine, diltiazem, verapamil, nicardipine), drugs able to control the contractility of the vessels, showed some positive results. Considering this data, we appraised the efficacy of flunarizine, another calcium-entry-blocker, in a preliminary study of 28 patients (23 females, 5 males, aged between 15 and 48 years) suffering from Raynaud's disease. Apart from a statistically insignificant improvement of subjective symptoms (i.e. acroparesthesias, cold extremities) flunarizine (10 mg/day for 1 month) did not have positive results. Finally, this drug caused some side-effects: drowsiness, increase of weight and appetite, but without a real necessity for withdrawal of therapy.

  6. Calcium carbonate polyamorphism and its role in biomineralization: how many amorphous calcium carbonates are there?

    Science.gov (United States)

    Cartwright, Julyan H E; Checa, Antonio G; Gale, Julian D; Gebauer, Denis; Sainz-Díaz, C Ignacio

    2012-11-26

    Although the polymorphism of calcium carbonate is well known, and its polymorphs--calcite, aragonite, and vaterite--have been highly studied in the context of biomineralization, polyamorphism is a much more recently discovered phenomenon, and the existence of more than one amorphous phase of calcium carbonate in biominerals has only very recently been understood. Here we summarize what is known about polyamorphism in calcium carbonate as well as what is understood about the role of amorphous calcium carbonate in biominerals. We show that consideration of the amorphous forms of calcium carbonate within the physical notion of polyamorphism leads to new insights when it comes to the mechanisms by which polymorphic structures can evolve in the first place. This not only has implications for our understanding of biomineralization, but also of the means by which crystallization may be controlled in medical, pharmaceutical, and industrial contexts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Single dendrite-targeting interneurons generate branch-specific inhibition.

    Directory of Open Access Journals (Sweden)

    Caleb eStokes

    2014-11-01

    Full Text Available Microcircuits composed of dendrite-targeting inhibitory interneurons and pyramidal cells are fundamental elements of cortical networks, however, the impact of individual interneurons on pyramidal dendrites is unclear. Here, we combine paired recordings and calcium imaging to determine the spatial domain over which single dendrite-targeting interneurons influence pyramidal cells in olfactory cortex. We show that a major action of individual interneurons is to inhibit dendrites in a branch-specific fashion.

  8. Calcium-ATPases: Gene disorders and dysregulation in cancer.

    Science.gov (United States)

    Dang, Donna; Rao, Rajini

    2016-06-01

    Ca(2+)-ATPases belonging to the superfamily of P-type pumps play an important role in maintaining low, nanomolar cytoplasmic Ca(2+) levels at rest and priming organellar stores, including the endoplasmic reticulum, Golgi, and secretory vesicles with high levels of Ca(2+) for a wide range of signaling functions. In this review, we introduce the distinct subtypes of Ca(2+)-ATPases and their isoforms and splice variants and provide an overview of their specific cellular roles as they relate to genetic disorders and cancer, with a particular emphasis on recent findings on the secretory pathway Ca(2+)-ATPases (SPCA). Mutations in human ATP2A2, ATP2C1 genes, encoding housekeeping isoforms of the endoplasmic reticulum (SERCA2) and secretory pathway (SPCA1) pumps, respectively, confer autosomal dominant disorders of the skin, whereas mutations in other isoforms underlie various muscular, neurological, or developmental disorders. Emerging evidence points to an important function of dysregulated Ca(2+)-ATPase expression in cancers of the colon, lung, and breast where they may serve as markers of differentiation or novel targets for therapeutic intervention. We review the mechanisms underlying the link between calcium homeostasis and cancer and discuss the potential clinical relevance of these observations. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Calcium influx pathways in breast cancer: opportunities for pharmacological intervention.

    Science.gov (United States)

    Azimi, I; Roberts-Thomson, S J; Monteith, G R

    2014-02-01

    Ca(2+) influx through Ca(2+) permeable ion channels is a key trigger and regulator of a diverse set of cellular events, such as neurotransmitter release and muscle contraction. Ca(2+) influx is also a regulator of processes relevant to cancer, including cellular proliferation and migration. This review focuses on calcium influx in breast cancer cells as well as the potential for pharmacological modulators of specific Ca(2+) influx channels to represent future agents for breast cancer therapy. Altered expression of specific calcium permeable ion channels is present in some breast cancers. In some cases, such changes can be related to breast cancer subtype and even prognosis. In vitro and in vivo models have now helped identify specific Ca(2+) channels that play important roles in the proliferation and invasiveness of breast cancer cells. However, some aspects of our understanding of Ca(2+) influx in breast cancer still require further study. These include identifying the mechanisms responsible for altered expression and the most effective therapeutic strategy to target breast cancer cells through specific Ca(2+) channels. The role of Ca(2+) influx in processes beyond breast cancer cell proliferation and migration should become the focus of studies in the next decade. © 2013 The British Pharmacological Society.

  10. Fertilization in plants: is calcium a key player?

    Science.gov (United States)

    Dumas, Christian; Gaude, Thierry

    2006-04-01

    For many years, the physiological significance of Ca(2+) oscillations has been a matter of debate, but the potential to encode and transduce information in the pattern of an oscillation is obvious. In this review, we only consider transients and oscillations observed during fertilization in plants with the major focus on flowering plants. After presenting data related to algae, fertilization mechanisms in flowering plants are defined as a multi-step phenomenon, starting with pollination during which calcium plays a key role, especially during pollen-stigma interactions (compatible and incompatible reactions). The pollen tube serves as a guide and a pathway for the sperm cells on their course towards their female target cells. For many years, the pollen tube has also been studied as an easily accessible in vitro model to elucidate the role of calcium on tip growth. Finally, in flowering plants, a unique double fertilization system is present. Interesting data obtained from an in vitro fertilization system in maize are presented and discussed. In addition, the new approaches made possible by Arabidopsis and Torenia and their potential limitations are covered.

  11. Calcium-Induced calcium release during action potential firing in developing inner hair cells.

    Science.gov (United States)

    Iosub, Radu; Avitabile, Daniele; Grant, Lisa; Tsaneva-Atanasova, Krasimira; Kennedy, Helen J

    2015-03-10

    In the mature auditory system, inner hair cells (IHCs) convert sound-induced vibrations into electrical signals that are relayed to the central nervous system via auditory afferents. Before the cochlea can respond to normal sound levels, developing IHCs fire calcium-based action potentials that disappear close to the onset of hearing. Action potential firing triggers transmitter release from the immature IHC that in turn generates experience-independent firing in auditory neurons. These early signaling events are thought to be essential for the organization and development of the auditory system and hair cells. A critical component of the action potential is the rise in intracellular calcium that activates both small conductance potassium channels essential during membrane repolarization, and triggers transmitter release from the cell. Whether this calcium signal is generated by calcium influx or requires calcium-induced calcium release (CICR) is not yet known. IHCs can generate CICR, but to date its physiological role has remained unclear. Here, we used high and low concentrations of ryanodine to block or enhance CICR to determine whether calcium release from intracellular stores affected action potential waveform, interspike interval, or changes in membrane capacitance during development of mouse IHCs. Blocking CICR resulted in mixed action potential waveforms with both brief and prolonged oscillations in membrane potential and intracellular calcium. This mixed behavior is captured well by our mathematical model of IHC electrical activity. We perform two-parameter bifurcation analysis of the model that predicts the dependence of IHCs firing patterns on the level of activation of two parameters, the SK2 channels activation and CICR rate. Our data show that CICR forms an important component of the calcium signal that shapes action potentials and regulates firing patterns, but is not involved directly in triggering exocytosis. These data provide important insights

  12. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials

    Directory of Open Access Journals (Sweden)

    Selen Küçükkaya

    2016-01-01

    Full Text Available The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P>0.05. MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P<0.05. Biodentine showed significantly less cell viability (73% after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P<0.05. Despite the significant changes in cell viability over time, materials presented similar cytotoxicity profile. Biodentine and CEM can be considered as alternative materials for root-end surgery procedures.

  13. Store-operated calcium entry and increased endothelial cell permeability.

    Science.gov (United States)

    Norwood, N; Moore, T M; Dean, D A; Bhattacharjee, R; Li, M; Stevens, T

    2000-11-01

    We hypothesized that myosin light chain kinase (MLCK) links calcium release to activation of store-operated calcium entry, which is important for control of the endothelial cell barrier. Acute inhibition of MLCK caused calcium release from inositol trisphosphate-sensitive calcium stores and prevented subsequent activation of store-operated calcium entry by thapsigargin, suggesting that MLCK serves as an important mechanism linking store depletion to activation of membrane calcium channels. Moreover, in voltage-clamped single rat pulmonary artery endothelial cells, thapsigargin activated an inward calcium current that was abolished by MLCK inhibition. F-actin disruption activated a calcium current, and F-actin stabilization eliminated the thapsigargin-induced current. Thapsigargin increased endothelial cell permeability in the presence, but not in the absence, of extracellular calcium, indicating the importance of calcium entry in decreasing barrier function. Although MLCK inhibition prevented thapsigargin from stimulating calcium entry, it did not prevent thapsigargin from increasing permeability. Rather, inhibition of MLCK activity increased permeability that was especially prominent in low extracellular calcium. In conclusion, MLCK links store depletion to activation of a store-operated calcium entry channel. However, inhibition of calcium entry by MLCK is not sufficient to prevent thapsigargin from increasing endothelial cell permeability.

  14. The spatial pattern of atrial cardiomyocyte calcium signalling modulates contraction.

    Science.gov (United States)

    Mackenzie, Lauren; Roderick, H Llewelyn; Berridge, Michael J; Conway, Stuart J; Bootman, Martin D

    2004-12-15

    We examined the regulation of calcium signalling in atrial cardiomyocytes during excitation-contraction coupling, and how changes in the distribution of calcium impacts on contractility. Under control conditions, calcium transients originated in subsarcolemmal locations and showed local regeneration through activation of calcium-induced calcium release from ryanodine receptors. Despite functional ryanodine receptors being expressed at regular (approximately 2 microm) intervals throughout atrial myocytes, the subsarcolemmal calcium signal did not spread in a fully regenerative manner through the interior of a cell. Rather, there was a diminishing centripetal propagation of calcium. The lack of regeneration was due to mitochondria and SERCA pumps preventing the inward movement of calcium. Inhibiting these calcium buffering mechanisms allowed the globalisation of action potential-evoked responses. In addition, physiological positive inotropic agents, such as endothelin-1 and beta-adrenergic agonists, as well as enhanced calcium current, calcium store loading and inositol 1,4,5-trisphosphate infusion also led to regenerative global responses. The consequence of globalising calcium signals was a significant increase in cellular contraction. These data indicate how calcium signals and their consequences are determined by the interplay of multiple subcellular calcium management systems.

  15. Calcium Aluminate Cement Hydration Model

    Directory of Open Access Journals (Sweden)

    Matusinović, T.

    2011-01-01

    Full Text Available Calcium aluminate cement (AC is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (ϑ=5–20 °C and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0 on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group, Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC. Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3 due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8 based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1, was employed. Hydration kinetics after the induction period (ϑ < 20 °C had been successfully described (Fig. 4 and Table 2 by a proposed model (eq. (23 which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq

  16. The comparison of calcium ion release and pH changes from modified MTA and bioceramics in regeneration

    Science.gov (United States)

    Irawan, R. M.; Margono, A.; Djauhari, N.

    2017-08-01

    The surface reactions of bioactive materials release and change dissolutions triggering intracellular and extracellular responses. Calcium ion release can promote alkalinizing activity, which is needed in tissue regeneration. To analyze calcium ion release and pH changes in modified MTA and bioceramics as bioactive materials. Thirty samples, measuring 3 mm in diameter and 3 mm in height, were prepared, with 15 consisting of modified MTA and 15 consisting of bioceramics. Both materials were immersed in deionized water for an hour, then measured and transferred into fresh solutions and soaked for 48 hours or 168 hours. The measurements were conducted using an atom absorption spectrophotometer and pHmeter. Mann Whitney’s post hoc statistic test showed a significant difference among all the 1-hour, 48-hour, and 168-hour measurement groups, with a value of p ≤ 0.05. Bioceramics released more calcium ions and raised pH levels higher than modified MTA for each of the three soak-time groups. Bioceramics released more calcium ion and had higher pH level compared to modified MTA which contributed to the tissue regeneration.

  17. Do Calcium Supplements Predispose to Urolithiasis?

    Science.gov (United States)

    Kozyrakis, Diomidis; Paridis, Dionysios; Karatzas, Anastasios; Soukias, Georgios; Dailiana, Zoi

    2017-03-01

    The purpose of this study was to investigate the role of calcium supplements, with or without vitamin D, in urinary stone formation in healthy population and in osteoporotic patients as well. Moreover, this review aims to clarify whether or not, and above which dose, they are associated with the risk of lithiasis. A research in Medline, Embase, and Scopus databases up to September 2015 was conducted using the following keywords: calcium, supplements, vitamin D, complications, lithiasis, and urinary stone. All types of studies were taken into account (cohort studies, reviews, meta-analyses), and in case they fulfilled the inclusion criteria, they were included in our review. The analysis of the data showed that calcium supplements, probably in association with anti osteoporotic treatment, do not create a predisposition towards lithiasis formation among women suffering from osteoporosis, neither among non-osteoporotic older men. In healthy postmenopausal as well as younger women, the supplements might increase susceptibility to urinary stone formation in long-term basis. The consumption of calcium supplements with the meals could play a protective role in women and younger males. There is certain evidence that supplements containing citrate may be more beneficial over the rest of calcium supplements, particularly when consumed during the meal. Osteoporotic women and healthy men are not at risk of stone formation. On the contrary, healthy women should be aware of the potential risk of developing urinary lithiasis in long-term basis.

  18. Calcium's Role in Mechanotransduction during Muscle Development

    Directory of Open Access Journals (Sweden)

    Tatiana Benavides Damm

    2014-01-01

    Full Text Available Mechanotransduction is a process where cells sense their surroundings and convert the physical forces in their environment into an appropriate response. Calcium plays a crucial role in the translation of such forces to biochemical signals that control various biological processes fundamental in muscle development. The mechanical stimulation of muscle cells may for example result from stretch, electric and magnetic stimulation, shear stress, and altered gravity exposure. The response, mainly involving changes in intracellular calcium concentration then leads to a cascade of events by the activation of downstream signaling pathways. The key calcium-dependent pathways described here include the nuclear factor of activated T cells (NFAT and mitogen-activated protein kinase (MAPK activation. The subsequent effects in cellular homeostasis consist of cytoskeletal remodeling, cell cycle progression, growth, differentiation, and apoptosis, all necessary for healthy muscle development, repair, and regeneration. A deregulation from the normal process due to disuse, trauma, or disease can result in a clinical condition such as muscle atrophy, which entails a significant loss of muscle mass. In order to develop therapies against such diseased states, we need to better understand the relevance of calcium signaling and the downstream responses to mechanical forces in skeletal muscle. The purpose of this review is to discuss in detail how diverse mechanical stimuli cause changes in calcium homeostasis by affecting membrane channels and the intracellular stores, which in turn regulate multiple pathways that impart these effects and control the fate of muscle tissue.

  19. The calcium-sensing receptor and the hallmarks of cancer.

    Science.gov (United States)

    Tennakoon, Samawansha; Aggarwal, Abhishek; Kállay, Enikö

    2016-06-01

    The calcium-sensing receptor (CaSR) plays a pivotal role in systemic calcium metabolism by regulating parathyroid hormone secretion and urinary calcium excretion. The CaSR is ubiquitously expressed, implying a wide range of functions regulated by this receptor. Abnormal CaSR function affects the development of both calciotropic disorders such as hyperparathyroidism, and non-calciotropic disorders such as cardiovascular disease and cancer, which are the leading causes of mortality worldwide. The CaSR is able to bind a plethora of ligands; it interacts with multiple G protein subtypes, and regulates highly divergent downstream signalling pathways, depending on the cellular context. The CaSR is a key regulator for such diverse processes as hormone secretion, gene expression, inflammation, proliferation, differentiation, and apoptosis. Due to this pleiotropy, the CaSR is able to regulate cell fate and is implicated in the development of many types of benign or malignant tumours of the breast, prostate, parathyroid, and colon. In cancer, the CaSR appears to have paradoxical roles, and depending on the tissue involved, it is able to prevent or promote tumour growth. In tissues like the parathyroid or colon, the CaSR inhibits proliferation and induces terminal differentiation of the cells. Therefore, loss of the receptor, as seen in colorectal or parathyroid tumours, confers malignant potential, suggestive of a tumour suppressor role. In contrast, in prostate and breast tumours the expression of the CaSR is increased and it seems that it favours metastasis to the bone, acting as an oncogene. Deciphering the molecular mechanism driving the CaSR in the different tissues could lead to development of new allosteric drug compounds that selectively target the CaSR and have therapeutic potential for cancer. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen

  20. Effect of hydrochloric acid concentration on the selectivity of leaching of high-calcium dead-burned magnesite

    Directory of Open Access Journals (Sweden)

    Alena Fedoročková

    2010-03-01

    Full Text Available Leaching of particulate dead-burned magnesite with hydrochloric acid at 45 °C was investigated with special regard to the effectof acid concentration (from 0.1 M to 4.8 M on the rate of chemical dissolution of magnesium, calcium and iron. The leaching process wasfound to be mostly selective in the initial stage and the differences in dissolution rates decreased with an increase in the fraction of deadburnedmagnesite reacted.

  1. Effect of Angiotensin-Converting Enzyme Inhibitor/Calcium Antagonist Combination Therapy on Renal Function in Hypertensive Patients With Chronic Kidney Disease: Chikushi Anti-Hypertension Trial - Benidipine and Perindopril.

    Science.gov (United States)

    Okuda, Tetsu; Okamura, Keisuke; Shirai, Kazuyuki; Urata, Hidenori

    2018-02-01

    Appropriate blood pressure control suppresses progression of chronic kidney disease (CKD). If an angiotensin-converting enzyme (ACE) inhibitor is ineffective, adding a calcium antagonist is recommended. We compared the long-term effect of two ACE inhibitor/calcium antagonist combinations on renal function in hypertensive patients with CKD. Patients who failed to achieve the target blood pressure (systolic/diastolic: hypertensive patients with diabetic nephropathy, combined therapy with an ACE inhibitor and T/L type calcium antagonist may prevent deterioration of renal function more effectively than an ACE inhibitor/L type calcium antagonist combination.

  2. The Mitochondrial Calcium Uniporter controls skeletal muscle trophism in vivo

    Science.gov (United States)

    Mammucari, Cristina; Gherardi, Gaia; Zamparo, Ilaria; Raffaello, Anna; Boncompagni, Simona; Chemello, Francesco; Cagnin, Stefano; Braga, Alessandra; Zanin, Sofia; Pallafacchina, Giorgia; Zentilin, Lorena; Sandri, Marco; De Stefani, Diego; Protasi, Feliciano; Lanfranchi, Gerolamo; Rizzuto, Rosario

    2015-01-01

    Summary Muscle atrophy contributes to the poor prognosis of many pathophysiological conditions, but pharmacological therapies are still limited. Muscle activity leads to major swings in mitochondrial [Ca2+] which control aerobic metabolism, cell death and survival pathways. We have investigated in vivo the effects of mitochondrial Ca2+ homeostasis in skeletal muscle function and trophism, by overexpressing or silencing the Mitochondrial Calcium Uniporter (MCU). The results demonstrate that both in developing and in adult muscles MCU-dependent mitochondrial Ca2+ uptake has a marked trophic effect that does not depend on aerobic control, but impinges on two major hypertrophic pathways of skeletal muscle, PGC-1α4 and IGF1-AKT/PKB. In addition, MCU overexpression protects from denervation-induced atrophy. These data reveal a novel Ca2+-dependent organelle-to-nucleus signaling route, which links mitochondrial function to the control of muscle mass and may represent a possible pharmacological target in conditions of muscle loss. PMID:25732818

  3. Toxicity of calcium salts to aqueous microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Lakhina, K.G.; Dolganova, A.V.; Yakobi, L.K.

    1983-03-01

    This article investigates the toxicity of calcium to aqueous microogranisms by means of a procedure developed by VNII VODGEO (All-Union Scientific-Research Institute of Water Supply, Sewer Systems, Hydrotechnical Facilities, and Engineering Hydrogeology), with certain changes in the preparation of the culture water. Proposes that with this method, calcium toxicity can be determined for groups of microorganisms that are among the most important in biochemical wastewater treatment and self-purification of water bodies (saprophytes, phase I and II nitrifiers). Finds that calcium in the form of the hydroxide and chloride is nontoxic under the following conditions: for protozoa in concentrations up to 2 g/liter, for saprophytic bacteria up to 3 g/liter, for phase I nitrifiers up to 1 g/liter, and for phase II nitrifiers up to 0.1 g/liter.

  4. Magnesium and Calcium in Isolated Cell Nuclei

    Science.gov (United States)

    Naora, H.; Naora, H.; Mirsky, A. E.; Allfrey, V. G.

    1961-01-01

    The calcium and magnesium contents of thymus nuclei have been determined and the nuclear sites of attachment of these two elements have been studied. The nuclei used for these purposes were isolated in non-aqueous media and in sucrose solutions. Non-aqueous nuclei contain 0.024 per cent calcium and 0.115 per cent magnesium. Calcium and magnesium are held at different sites. The greater part of the magnesium is bound to DNA, probably to its phosphate groups. Evidence is presented that the magnesium atoms combined with the phosphate groups of DNA are also attached to mononucleotides. There is reason to believe that those DNA-phosphate groups to which magnesium is bound, less than 1/10th of the total, are metabolically active, while those to which histones are attached seem to be inactive. PMID:13727745

  5. Calcium concentration in the CAPD dialysate

    DEFF Research Database (Denmark)

    Bro, S; Brandi, L; Daugaard, H

    1998-01-01

    with a reduced dialysate Ca concentration (1.00, 1.25, or 1.35 mmol/L) improved the tolerance to calcium carbonate and/or vitamin D metabolites and reduced the need for Al-containing phosphate binders. When using dialysate Ca 1.25 or 1.35 mmol/L, the initial decrease of plasma Ca and increase of PTH could easily......), doses of calcium carbonate, doses of vitamin D analogs, and requirements of aluminum-containing phosphate binders. STUDY SELECTION: Eleven studies of nonselected CAPD patients, and 13 studies of CAPD patients with hypercalcemia were reviewed. RESULTS: In nonselected CAPD patients, treatment...... for the progression of secondary hyperparathyroidism. When hypercalcemia was present in combination with suppressed PTH levels, a controlled increase of PTH could be obtained with a temporary discontinuation of vitamin D and/or a reduction of calcium carbonate treatment in combination with a dialysate Ca...

  6. OSTEOPOROSIS IN CALCIUM PYROPHOSPHATE CRYSTAL DEPOSITION DISEASE

    Directory of Open Access Journals (Sweden)

    S A Vladimirov

    2013-01-01

    Full Text Available Objective: to study the incidence of osteoporosis (OP in patients with calcium pyrophosphate crystal deposition disease (CPCDD. Subjects and methods. Eighty patients with CPCDD were examined. Bone mineral density (BMD of the forearm, lumbar spine, and femoral neck was determined by dual-energy X-ray absorptiometry. Laboratory diagnosis involved determination of the blood levels of C-reactive protein, parathyroid hormone, calcium, magnesium, and phosphorus and the daily urinary excretion of calcium and phosphates. Results. The patients with OP were significantly older than those with normal BMD and osteopenia. Forearm bones were the most common isolated location of OP and osteopenia. Injuries in the history, traumatic fractures, and the intake of diuretics were somewhat more common in the patients diagnosed with OP. The incidence of hyperparathyroidism did not differ significantly in the groups.

  7. In situ preparation of Calcium hydroxide films

    Energy Technology Data Exchange (ETDEWEB)

    Dahle, S.; Voigts, F. [Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Maus-Friedrichs, W., E-mail: w.maus-friedrichs@pe.tu-clausthal.de [Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Clausthaler Zentrum fuer Materialtechnik, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany)

    2011-10-31

    The in situ preparation of Calcium hydroxide films in an ultra high vacuum (UHV) is constrained by the decomposition of species at the surface and the absence of OH bulk diffusion. Therefore, it is not possible to prepare such films simply by water exposure to a Calcium layer. We present four different approaches for the preparation of Ca(OH){sub 2} films in an UHV. Two of these methods are found to be ineffective for the preparation, the other two are shown to produce Calcium hydroxide films. Both of the two effective procedures make use of H{sub 2} gas exposure. Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy, and X-ray Photoelectron Spectroscopy are employed to verify quality and purity of the films.

  8. In situ preparation of calcium carbonate films

    Energy Technology Data Exchange (ETDEWEB)

    Dahle, S. [Clausthaler Zentrum fuer Materialtechnik, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Voigts, F. [Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Maus-Friedrichs, W., E-mail: w.maus-friedrichs@pe.tu-clausthal.de [Clausthaler Zentrum fuer Materialtechnik, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany)

    2012-01-01

    The in situ preparation of calcium carbonate films in an ultra high vacuum (UHV) is inhibited by the decomposition of CO{sub 2} molecules at the surface and the absence of CO{sub 2} bulk diffusion. Therefore, it is not possible to prepare such films simply by CO{sub 2} exposure to a calcium layer. We investigated different approaches for the preparation of CaCO{sub 3} films in an UHV. Among these, only the simultaneous evaporation of Ca atoms in a mixed O{sub 2} and CO{sub 2} atmosphere is able to produce well defined stoichiometric calcium carbonate films. Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy and X-ray Photoelectron Spectroscopy are employed to verify quality and purity of the films.

  9. Calcination of calcium carbonate and blend therefor

    Science.gov (United States)

    Mallow, William A.; Dziuk, Jr., Jerome J.

    1989-01-01

    A method for calcination of a calcium carbonate material comprising heating the calcium carbonate material to a temperature and for a time sufficient to calcine the material to the degree desired while in the presence of a catalyst; said catalyst comprising at least one fused salt having the formula MCO.sub.3.CaCO.sub.3.CaO.H.sub.2 O.sub.x, wherein M is an alkali metal and x is 0 to 1 and formed by fusing MCO.sub.3 and CaCO.sub.3 in a molar ratio of about 1:2 to 2:1, and a blend adapted to be heated to CaO comprising a calcium carbonate material and at least one such fused salt.

  10. Aspirin plus calcium supplementation to prevent superimposed preeclampsia: a randomized trial

    Directory of Open Access Journals (Sweden)

    E.V. Souza

    2014-05-01

    Full Text Available Preeclampsia is an important cause of maternal and perinatal morbidity and mortality. Previous studies have tested calcium supplementation and aspirin separately to reduce the incidence of preeclampsia but not the effects of combined supplementation. The objective of this study was to investigate the effectiveness of aspirin combined with calcium supplementation to prevent preeclampsia in women with chronic hypertension. A double-blind, placebo-controlled randomized clinical trial was carried out at the antenatal clinic of a large university hospital in São Paulo, SP, Brazil. A total of 49 women with chronic hypertension and abnormal uterine artery Doppler at 20-27 weeks gestation were randomly assigned to receive placebo (N = 26 or 100 mg aspirin plus 2 g calcium (N = 23 daily until delivery. The main outcome of this pilot study was development of superimposed preeclampsia. Secondary outcomes were fetal growth restriction and preterm birth. The rate of superimposed preeclampsia was 28.6% lower among women receiving aspirin plus calcium than in the placebo group (52.2 vs 73.1%, respectively, P=0.112. The rate of fetal growth restriction was reduced by 80.8% in the supplemented group (25 vs 4.8% in the placebo vs supplemented groups, respectively; P=0.073. The rate of preterm birth was 33.3% in both groups. The combined supplementation of aspirin and calcium starting at 20-27 weeks of gestation produced a nonsignificant decrease in the incidence of superimposed preeclampsia and fetal growth restriction in hypertensive women with abnormal uterine artery Doppler.

  11. Effect of phase composition of calcium silicate phosphate component on properties of brushite based composite cements

    Energy Technology Data Exchange (ETDEWEB)

    Sopcak, T., E-mail: tsopcak@imr.saske.sk [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia); Medvecky, L.; Giretova, M.; Stulajterova, R.; Durisin, J. [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia); Girman, V. [Institute of Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 04001 Kosice (Slovakia); Faberova, M. [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia)

    2016-07-15

    The composite cement mixtures were prepared by mixing brushite (B) with, the amorphous hydrated calcium silicate phosphate (CSPH) or annealed calcium silicate phosphate (CSP composed of Si-saturated hydroxyapatite, wollastonite and silica) phases and water as liquid component. The contents of the silicate-phosphate phase in composites were 10.30 and 50 wt%. The significant effect of both the Ca/P ratio and different solubility of calcium silicate phosphate component in starting cement systems on setting time and phase composition of the final composite cements was demonstrated. The compressive strength of the set cements increased with the filler addition and the highest value (~ 48 MPa) exhibited the 50CSP/B cement composite. The final setting times of the composite cements decreased with the CSPH addition from about 25 to 17 min in 50CSHP/B and setting time of CSP/B composites was around 30 min. The higher content of silica in cements caused the precipitation of fine hydroxyapatite particles in the form of nanoneedles or thin plates perpendicularly oriented to sample surface. The analysis of in vitro cement cytotoxicity demonstrated the strong reduction in cytotoxicity of 10CSPH/B composite with time of cultivation (a low cytotoxicity after 9 days of culture) contrary to cements with higher calcium silicate-phosphate content. These results were attributed to the different surface topography of composite substrates and possible stimulation of cell proliferation by the slow continuously release of ions from 10CSPH/B cement. - Highlights: • Ca/P ratio and solubility of calcium silicate-phosphate components affect the self-setting properties of cements. • Strong relationship between the composite in vitro cytotoxicity and surface microtopography was demonstrated. • Plate-like morphology of coarser particles allowed cells to better adhere and proliferate as compared with nanoneedles.

  12. Characterization of Calcium Compounds in Opuntia ficus indica as a Source of Calcium for Human Diet

    Directory of Open Access Journals (Sweden)

    Isela Rojas-Molina

    2015-01-01

    Full Text Available Analyses of calcium compounds in cladodes, soluble dietary fiber (SDF, and insoluble dietary fiber (IDF of Opuntia ficus indica are reported. The characterization of calcium compounds was performed by using Scanning Electron Microscopy, Energy Dispersive Spectrometry, X-ray diffraction, and infrared spectroscopy. Atomic Absorption Spectroscopy and titrimetric methods were used for quantification of total calcium and calcium compounds. Whewellite (CaC2O4·H2O, weddellite (CaC2O4·(H2O2.375, and calcite (CaCO3 were identified in all samples. Significant differences (P≤0.05 in the total calcium contents were detected between samples. CaC2O4·H2O content in cladodes and IDF was significantly higher (P≤0.05 in comparison to that observed in SDF, whereas minimum concentration of CaCO3 was detected in IDF with regard to CaCO3 contents observed in cladodes and SDF. Additionally, molar ratio oxalate : Ca2+ in all samples changed in a range from 0.03 to 0.23. These results support that calcium bioavailability in O. ficus indica modifies according to calcium compounds distribution.

  13. Calcium carbonate phase transformations during the carbonation reaction of calcium heavy alkylbenzene sulfonate overbased nanodetergents preparation.

    Science.gov (United States)

    Chen, Zhaocong; Xiao, Shan; Chen, Feng; Chen, Dongzhong; Fang, Jianglin; Zhao, Min

    2011-07-01

    The preparation and application of overbased nanodetergents with excess alkaline calcium carbonate is a good example of nanotechnology in practice. The phase transformation of calcium carbonate is of extensive concern since CaCO(3) serves both as an important industrial filling material and as the most abundant biomineral in nature. Industrially valuable overbased nanodetergents have been prepared based on calcium salts of heavy alkylbenzene sulfonate by a one-step process under ambient pressure, the carbonation reaction has been monitored by the instantaneous temperature changes and total base number (TBN). A number of analytical techniques such as TGA, DLS, SLS, TEM, FTIR, and XRD have been utilized to explore the carbonation reaction process and phase transformation mechanism of calcium carbonate. An enhanced understanding on the phase transformation of calcium carbonate involved in calcium sulfonate nanodetergents has been achieved and it has been unambiguously demonstrated that amorphous calcium carbonate (ACC) transforms into the vaterite polymorph rather than calcite, which would be of crucial importance for the preparation and quality control of lubricant additives and greases. Our results also show that a certain amount of residual Ca(OH)(2) prevents the phase transformation from ACC to crystalline polymorphs. Moreover, a vaterite nanodetergent has been prepared for the first time with low viscosity, high base number, and uniform particle size, nevertheless a notable improvement on its thermal stability is required for potential applications. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Comparison of Ferrous Calcium Silicate Slag and Calcium Ferrite Slag Interactions with Magnesia-Chrome Refractories

    Science.gov (United States)

    Kaur, R. R.; Swinbourne, D. R.; Wadsley, M. W.; Nexhip, C.

    2011-06-01

    The cost of maintaining and eventually replacing refractories as a result of slag attack is a significant cost component in the copper industry. Converting matte to blister copper takes place in reactors lined with direct-bonded magnesia-chrome refractories, and several continuous converting operations use calcium ferrite slag. Unfortunately, the low viscosity of calcium ferrite slag makes it aggressive toward the refractories. Ferrous calcium silicate (FCS) slag has been proposed as a replacement; however, the effect of this slag on magnesia-chrome refractories has not been studied. In this work, the interactions between FCS slag and magnesia-chrome refractory at 1573 K (1300 °C) with an oxygen partial pressure of 10-6 atm were studied and compared with that experienced with calcium ferrite slag under the same conditions. Both slags penetrated the pores in the refractory and caused compositional change in the chromite spinel intergranular bonding phase through cation interdiffusion, which resulted in cracking and debonding of periclase grains. It was observed that the refractory was penetrated much more deeply by calcium ferrite slag than FCS slag because of the higher surface tension and lower viscosity of calcium ferrite slag. As a result, the refractory was attacked less by FCS slag than it was by calcium ferrite slag. It is concluded that the use of FCS slag in continuous copper converting is likely to extend refractory life.

  15. Meta-analysis of genome-wide association studies identifies six new Loci for serum calcium concentrations.

    Directory of Open Access Journals (Sweden)

    Conall M O'Seaghdha

    Full Text Available Calcium is vital to the normal functioning of multiple organ systems and its serum concentration is tightly regulated. Apart from CASR, the genes associated with serum calcium are largely unknown. We conducted a genome-wide association meta-analysis of 39,400 individuals from 17 population-based cohorts and investigated the 14 most strongly associated loci in ≤ 21,679 additional individuals. Seven loci (six new regions in association with serum calcium were identified and replicated. Rs1570669 near CYP24A1 (P = 9.1E-12, rs10491003 upstream of GATA3 (P = 4.8E-09 and rs7481584 in CARS (P = 1.2E-10 implicate regions involved in Mendelian calcemic disorders: Rs1550532 in DGKD (P = 8.2E-11, also associated with bone density, and rs7336933 near DGKH/KIAA0564 (P = 9.1E-10 are near genes that encode distinct isoforms of diacylglycerol kinase. Rs780094 is in GCKR. We characterized the expression of these genes in gut, kidney, and bone, and demonstrate modulation of gene expression in bone in response to dietary calcium in mice. Our results shed new light on the genetics of calcium homeostasis.

  16. Assessment of salivary calcium, phosphate, magnesium, pH, and flow rate in healthy subjects, periodontitis, and dental caries

    Directory of Open Access Journals (Sweden)

    K S Rajesh

    2015-01-01

    Full Text Available Aim: This study was conducted to estimate and compare inorganic salivary calcium, phosphate, magnesium, salivary flow rate, and pH of unstimulated saliva and oral hygiene status of healthy subjects, subjects with periodontitis and dental caries, and to correlate salivary calcium level with number of intact teeth. Materials and Methods: The study population consisted of 48 systemically healthy subjects in the age group of 18-55 years, which was further divided into three groups: healthy, periodontitis, and dental caries. Oral hygiene index-simplified, probing pocket depth, clinical attachment level, the number of intact teeth, and active carious lesions were recorded. Estimation of inorganic salivary calcium, phosphate, and magnesium was performed spectrophotometrically using Vitros 5.1 FS. Statistical analysis was performed using the one-way analysis of variance test at 5% significance level. Results: There was a statistically significant increase in inorganic salivary calcium, phosphate, pH, flow rate, and poor oral hygiene status in periodontitis group compared to dental caries and healthy group. Conclusion: Subjects with increased inorganic salivary calcium, phosphate, pH, flow rate, and poor oral hygiene are at a higher risk of developing periodontitis. Since there is increased remineralization potential, these subjects have more number of intact teeth compared to the dental caries group.

  17. The Role of the Calcium-sensing Receptor in Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Rodland, Karin D.

    2004-03-01

    The cell surface calcium receptor (Ca2+ receptor) is a particularly difficult receptor to study because its primary physiological ligand, Ca2+, affects numerous biological processes both within and outside of cells. Because of this, distinguishing effects of extracellular Ca2+ mediated by the Ca2+ receptor from those mediated by other mechanisms is challenging. Certain pharmacological approaches, however, when combined with appropriate experimental designs, can be used to more confidently identify cellular responses regulated by the Ca2+ receptor and select those that might be targeted therapeutically. The Ca2+ receptor on parathyroid cells, because it is the primary mechanism regulating secretion of parathyroid hormone (PTH), is one such target. Calcimimetic compounds, which active this Ca2+ receptor and lower circulating levels of PTH, have been developed for treating hyperparathyroidism. The converse pharmaceutical approach, involving calcilytic compounds that block parathyroid cell Ca2+ receptors and stimulate PTH secretion thereby providing an anabolic therapy for osteoporosis, still awaits clinical validation. Although Ca2+ receptors are expressed throughout the body and in many tissues that are not intimately involved in systemic Ca2+ homeostasis, their physiological and/or pathological significance remains speculative and their value as therapeutic targets is unknown.

  18. Parasitoid wasp venom SERCA regulates Drosophila calcium levels and inhibits cellular immunity.

    Science.gov (United States)

    Mortimer, Nathan T; Goecks, Jeremy; Kacsoh, Balint Z; Mobley, James A; Bowersock, Gregory J; Taylor, James; Schlenke, Todd A

    2013-06-04

    Because parasite virulence factors target host immune responses, identification and functional characterization of these factors can provide insight into poorly understood host immune mechanisms. The fruit fly Drosophila melanogaster is a model system for understanding humoral innate immunity, but Drosophila cellular innate immune responses remain incompletely characterized. Fruit flies are regularly infected by parasitoid wasps in nature and, following infection, flies mount a cellular immune response culminating in the cellular encapsulation of the wasp egg. The mechanistic basis of this response is largely unknown, but wasps use a mixture of virulence proteins derived from the venom gland to suppress cellular encapsulation. To gain insight into the mechanisms underlying wasp virulence and fly cellular immunity, we used a joint transcriptomic/proteomic approach to identify venom genes from Ganaspis sp.1 (G1), a previously uncharacterized Drosophila parasitoid species, and found that G1 venom contains a highly abundant sarco/endoplasmic reticulum calcium ATPase (SERCA) pump. Accordingly, we found that fly immune cells termed plasmatocytes normally undergo a cytoplasmic calcium burst following infection, and that this calcium burst is required for activation of the cellular immune response. We further found that the plasmatocyte calcium burst is suppressed by G1 venom in a SERCA-dependent manner, leading to the failure of plasmatocytes to become activated and migrate toward G1 eggs. Finally, by genetically manipulating plasmatocyte calcium levels, we were able to alter fly immune success against G1 and other parasitoid species. Our characterization of parasitoid wasp venom proteins led us to identify plasmatocyte cytoplasmic calcium bursts as an important aspect of fly cellular immunity.

  19. Calcium Oxalate: A Surface Treatment for Limestone

    Directory of Open Access Journals (Sweden)

    Tody M. Cezar

    1998-05-01

    Full Text Available This paper looks at the artificially induced surface conversion of calcium carbonate to the more durable calcium oxalate. Extensive research is being carried out on wall paintings and marble sculpture at the Opicificio delle Pietre Dure e Laboratori di Restauro in Florence, Encouraged by their work, I have researched the effectiveness of the conversion on English limestones. The treated samples have been compared to untreated samples for appearance, hardness, resistance to acid and alkali, porosity, and durability. The results have been assessed considering ease of use, effectiveness, and the appropriateness of the treatment.

  20. Evolutionary Diversity of the Mitochondrial Calcium Uniporter

    Science.gov (United States)

    Bick, Alexander G.; Calvo, Sarah E.; Mootha, Vamsi K.

    2012-01-01

    Calcium uptake into mitochondria occurs via a recently identified ion channel called the uniporter. Here, we characterize the phylogenomic distribution of the uniporter’s membrane-spanning pore subunit (MCU) and regulatory partner (MICU1). Homologs of both components tend to co-occur in all major branches of eukaryotic life, but both have been lost along certain protozoan and fungal lineages. Several bacterial genomes also contain putative MCU homologs that may represent prokaryotic calcium channels. The analyses indicate that the uniporter may have been an early feature of mitochondria. PMID:22605770

  1. Does the use of calcium ionophore during artificial oocyte activation demonstrate an effect on pregnancy rate? A meta-analysis.

    Science.gov (United States)

    Murugesu, Sughashini; Saso, Srdjan; Jones, Benjamin P; Bracewell-Milnes, Timothy; Athanasiou, Thanos; Mania, Anastasia; Serhal, Paul; Ben-Nagi, Jara

    2017-09-01

    To study the effect, if any, of calcium ionophore as a method of artificial oocyte activation (AOA) on pregnancy outcomes and fertilization rates. Meta-analysis of randomized controlled trials, prospective observational and retrospective trials, case reports, and a case-control trial. University-affiliated teaching hospital. Infertile couples undergoing fertilization treatment. Use of calcium ionophore during AOA. Odds ratio (OR) as the summary statistic for binary variables was used. Both a fixed and random effects model were applied. Subgroup analysis using quantitative methodology (risk of bias, metaregression) and graphical comparison (funnel plot) assessed statistical heterogeneity. Fourteen studies were selected. AOA with calcium ionophore increased the overall clinical pregnancy rate (per ET; OR = 3.48; 95% confidence interval [CI], 1.65-7.37) and the live birth rate (OR = 3.33; 95% CI, 1.50-7.39). This effect of adding calcium ionophore was further demonstrated with fertilization, cleavage, blastocyst, and implantation rates. Subgroup analysis further supported our findings (studies where n > 10 in both arms; random and fixed effects models). A metaregression (beta = -.145) found that as the quality of the study increases, the effect of calcium ionophore is significantly more pronounced with regards to overall pregnancy rate. AOA with calcium ionophore treatment after intracytoplasmic sperm injection (ICSI) results in a statistically significant improvement in fertilization, cleavage, blastulation, and implantation rates, as well as overall pregnancy and live-birth rates. The conclusion of this systematic review, demonstrating a strong effect of calcium ionophore use, is reassuring and promising, particularly for couples for whom ICSI alone yields poor fertilization rates. Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  2. Effect of Coated Urea with Humic-Calcium on Transformation of Nitrogen in Coastal Sandy Soil: A Soil Column Method

    Directory of Open Access Journals (Sweden)

    Sulakhudin

    2010-01-01

    Full Text Available Effect of Coated Urea with Humic-Calcium on Transformation of Nitrogen in Coastal Sandy Soil: A Soil ColumnMethod (Sulakhudin, A Syukur, D Shiddieq and T Yuwono: In coastal sandy soil, mainly nitrogen losses due toleaching resulted to low fertilizer efficiency. Slow-release N fertilizers are proposed to minimize these losses, andhumic-calcium coated urea has been examined. A soil column method was used to compare the effects of coated ureawith humic-calcium on transformation and leaching loss of N in coastal sandy soil. The experiment aid to compare twokinds sources of humic substances (cow manure and peat which mixed with calcium as coated urea on transformation,vertical distribution and leaching N in coastal sandy soil. The concentration of humic-calcium coated urea i.e.1%, 5%and 10% based on their weight. The results showed that urea coated with humic-calcium from cow manure (UCHMand humic-calcium from peat (UCHP increased the N total and available N in the soil and decreased leaching loss ofN from the soil column. Compared to UCHP, UCHM in all concentration showed N-nitrate higher than N-ammonium onincubation length 2, 4 and 6 weeks. The N leached from a costal sandy soil with application coated urea with UCHMranged from 21.18% to 23.72% of the total N added as fertilizer, for coated urea with UCHP they ranged between21.44% and 23.25%, whereas for urea (control reached 29.48%. Leaching losses of mineral N were lower when ureacoated with UCHM compared to urea coated with UCHP or urea fertilizer. The study concluded that the UCHM isbetter than UCHP in decreasing N leached from coastal sandy soil

  3. Biotic Nitrogen Enrichment Regulates Calcium Sources to Forests

    Science.gov (United States)

    Pett-Ridge, J. C.; Perakis, S. S.; Hynicka, J. D.

    2015-12-01

    Calcium is an essential nutrient in forest ecosystems that is susceptible to leaching loss and depletion. Calcium depletion can affect plant and animal productivity, soil acid buffering capacity, and fluxes of carbon and water. Excess nitrogen supply and associated soil acidification are often implicated in short-term calcium loss from soils, but the long-term role of nitrogen enrichment on calcium sources and resupply is unknown. Here we use strontium isotopes (87Sr/86Sr) as a proxy for calcium to investigate how soil nitrogen enrichment from biological nitrogen fixation interacts with bedrock calcium to regulate both short-term available supplies and the long-term sources of calcium in montane conifer forests. Our study examines 22 sites in western Oregon, spanning a 20-fold range of bedrock calcium on sedimentary and basaltic lithologies. In contrast to previous studies emphasizing abiotic control of weathering as a determinant of long-term ecosystem calcium dynamics and sources (via bedrock fertility, climate, or topographic/tectonic controls) we find instead that that biotic nitrogen enrichment of soil can strongly regulate calcium sources and supplies in forest ecosystems. For forests on calcium-rich basaltic bedrock, increasing nitrogen enrichment causes calcium sources to shift from rock-weathering to atmospheric dominance, with minimal influence from other major soil forming factors, despite regionally high rates of tectonic uplift and erosion that can rejuvenate weathering supply of soil minerals. For forests on calcium-poor sedimentary bedrock, we find that atmospheric inputs dominate regardless of degree of nitrogen enrichment. Short-term measures of soil and ecosystem calcium fertility are decoupled from calcium source sustainability, with fundamental implications for understanding nitrogen impacts, both in natural ecosystems and in the context of global change. Our finding that long-term nitrogen enrichment increases forest reliance on atmospheric

  4. Voltage-gated calcium flux mediatesEscherichia colimechanosensation.

    Science.gov (United States)

    Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

    2017-08-29

    Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

  5. Calcium intake, polymorphisms of the calcium-sensing receptor, and recurrent/aggressive prostate cancer.

    Science.gov (United States)

    Binder, Moritz; Shui, Irene M; Wilson, Kathryn M; Penney, Kathryn L; Mucci, Lorelei A; Kibel, Adam S

    2015-12-01

    To assess whether calcium intake and common genetic variants of the calcium-sensing receptor (CASR) are associated with either aggressive prostate cancer (PCa) or disease recurrence after prostatectomy. Calcium intake at diagnosis was assessed, and 65 common single-nucleotide polymorphisms (SNPs) in CASR were genotyped in 886 prostatectomy patients. We investigated the association between calcium intake and CASR variants with both PCa recurrence and aggressiveness (defined as Gleason score ≥4 + 3, stage ≥pT3, or nodal-positive disease). A total of 285 men had aggressive disease and 91 experienced recurrence. A U-shaped relationship between calcium intake and both disease recurrence and aggressiveness was observed. Compared to the middle quintile, the HR for disease recurrence was 3.07 (95% CI 1.41-6.69) for the lowest quintile and 3.21 (95% CI 1.47-7.00) and 2.97 (95% CI 1.37-6.45) for the two upper quintiles, respectively. Compared to the middle quintile, the OR for aggressive disease was 1.80 (95% CI 1.11-2.91) for the lowest quintile and 1.75 (95% CI 1.08-2.85) for the highest quintile of calcium intake. The main effects of CASR variants were not associated with PCa recurrence or aggressiveness. In the subgroup of patients with moderate calcium intake, 31 SNPs in four distinct blocks of high linkage disequilibrium were associated with PCa recurrence. We observed a protective effect of moderate calcium intake for PCa aggressiveness and recurrence. While CASR variants were not associated with these outcomes in the entire cohort, they may be associated with disease recurrence in men with moderate calcium intakes.

  6. Do calcium buffers always slow down the propagation of calcium waves?

    Science.gov (United States)

    Tsai, Je-Chiang

    2013-12-01

    Calcium buffers are large proteins that act as binding sites for free cytosolic calcium. Since a large fraction of cytosolic calcium is bound to calcium buffers, calcium waves are widely observed under the condition that free cytosolic calcium is heavily buffered. In addition, all physiological buffered excitable systems contain multiple buffers with different affinities. It is thus important to understand the properties of waves in excitable systems with the inclusion of buffers. There is an ongoing controversy about whether or not the addition of calcium buffers into the system always slows down the propagation of calcium waves. To solve this controversy, we incorporate the buffering effect into the generic excitable system, the FitzHugh-Nagumo model, to get the buffered FitzHugh-Nagumo model, and then to study the effect of the added buffer with large diffusivity on traveling waves of such a model in one spatial dimension. We can find a critical dissociation constant (K = K(a)) characterized by system excitability parameter a such that calcium buffers can be classified into two types: weak buffers (K ∈ (K(a), ∞)) and strong buffers (K ∈ (0, K(a))). We analytically show that the addition of weak buffers or strong buffers but with its total concentration b(0)(1) below some critical total concentration b(0,c)(1) into the system can generate a traveling wave of the resulting system which propagates faster than that of the origin system, provided that the diffusivity D1 of the added buffers is sufficiently large. Further, the magnitude of the wave speed of traveling waves of the resulting system is proportional to √D1 as D1 --> ∞. In contrast, the addition of strong buffers with the total concentration b(0)(1) > b(0,c)(1) into the system may not be able to support the formation of a biologically acceptable wave provided that the diffusivity D1 of the added buffers is sufficiently large.

  7. Calcium and vitamin D intake by postmenopausal women with osteoporosis in Spain: an observational calcium and vitamin D intake (CaVIT) study.

    Science.gov (United States)

    Fan, Tao; Nocea, Gonzalo; Modi, Ankita; Stokes, Leah; Sen, Shuvayu S

    2013-01-01

    Osteoporotic fractures are important causes of morbidity, mortality, and increased health care costs. However, the risk of osteoporotic fractures can be decreased, with clinical studies supporting the use of calcium and vitamin D supplements to promote bone health. Vitamin D insufficiency is widespread, particularly among postmenopausal women with osteoporosis, and this indicates that dietary intake is suboptimal, even though vitamin D supplements are widely available. We conducted an observational study, using telephone surveys, to estimate vitamin D and calcium intake and the use of prescription osteoporosis medications in Spanish women aged ≥ 50 years with osteoporosis. Among the study participants, mean dietary calcium intake was 1239 mg/day and generally appeared sufficient in terms of the recommended daily intake guidance documents. Participants aged ≥ 75 years had a significantly lower mean dietary calcium intake (988 mg/day), thus one-half were below the level advised by the World Health Organization. Daily calcium intake was also lower in participants who were not taking prescription medications for bone health. Dietary vitamin D intake was 167 IU/day, which is well below both the established target dose (400 IU/day) and the more recent, higher guideline recommended for postmenopausal women (800-1300 IU/day). Dietary vitamin D intake was even lower for participants aged ≥ 75 years (120 IU/day) and was not related to the use of bone health prescription medications. These results support the need for greater promotion of the benefits of higher vitamin D intake in Spanish women with osteoporosis.

  8. Calcium and vitamin D intake by postmenopausal women with osteoporosis in Spain: an observational calcium and vitamin D intake (CaVIT study

    Directory of Open Access Journals (Sweden)

    Fan T

    2013-06-01

    Full Text Available Tao Fan,1 Gonzalo Nocea,2 Ankita Modi,3 Leah Stokes,1 Shuvayu S Sen1 1Global Outcomes Research, Merck & Company, Whitehouse Station, NJ, USA; 2Department of Outcomes Research, Merck, Sharp and Dohme Spain, Madrid, Spain; 3Global Human Health, Outcomes Research, Merck & Company, Whitehouse Station, NJ, USA Background: Osteoporotic fractures are important causes of morbidity, mortality, and increased health care costs. However, the risk of osteoporotic fractures can be decreased, with clinical studies supporting the use of calcium and vitamin D supplements to promote bone health. Vitamin D insufficiency is widespread, particularly among postmenopausal women with osteoporosis, and this indicates that dietary intake is suboptimal, even though vitamin D supplements are widely available. Methods: We conducted an observational study, using telephone surveys, to estimate vitamin D and calcium intake and the use of prescription osteoporosis medications in Spanish women aged ≥ 50 years with osteoporosis. Results: Among the study participants, mean dietary calcium intake was 1239 mg/day and generally appeared sufficient in terms of the recommended daily intake guidance documents. Participants aged ≥ 75 years had a significantly lower mean dietary calcium intake (988 mg/day, thus one-half were below the level advised by the World Health Organization. Daily calcium intake was also lower in participants who were not taking prescription medications for bone health. Dietary vitamin D intake was 167 IU/day, which is well below both the established target dose (400 IU/day and the more recent, higher guideline recommended for postmenopausal women (800–1300 IU/day. Dietary vitamin D intake was even lower for participants aged ≥75 years (120 IU/day and was not related to the use of bone health prescription medications. Conclusion: These results support the need for greater promotion of the benefits of higher vitamin D intake in Spanish women with

  9. Vitamin d deficiency is associated with insulin resistance independent of intracellular calcium, dietary calcium and serum levels of parathormone, calcitriol and calcium in premenopausal women.

    Science.gov (United States)

    Ferreira, Thaís da Silva; Rocha, Tatiana Martins; Klein, Márcia Regina Simas Torres; Sanjuliani, Antonio Felipe

    2015-04-01

    There is evidence that vitamin D deficiency is associated with increased risk of cardiovascular disease. However, it is not known if this association is independent of dietary calcium, intracellular calcium and serum levels of parathormone, calcitriol and calcium. To investigate the independent relationship of vitamin D deficiency with insulin resistance, lipid profile, inflammatory status, blood pressure and endothelial function. Cross-sectional study conducted with 73 healthy Brazilian premenopausal women aged 18 - 50 years. All participants were evaluated for: 25 hydroxyvitamin D serum levels, anthropometric parameters, body composition, calcium metabolism, insulin resistance, lipoprotein profile, inflammatory status, blood pressure and endothelial function. Endothelial function was assessed by reactive hyperemia index using Endo-PAT 2000®. Women were stratified in two groups: with vitamin D deficiency (25 hydroxyvitamin D independent of dietary calcium, intracellular calcium and serum levels of parathormone, calcitriol and calcium in healthy premenopausal women. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  10. Calcium, cancer and killing: the role of calcium in killing cancer cells by cytotoxic T lymphocytes and natural killer cells.

    Science.gov (United States)

    Schwarz, Eva C; Qu, Bin; Hoth, Markus

    2013-07-01

    Killing cancer cells by cytotoxic T lymphocytes (CTL) and by natural killer (NK) cells is of vital importance. Cancer cell proliferation and apoptosis depend on the intracellular Ca(2+) concentration, and the expression of numerous ion channels with the ability to control intracellular Ca(2+) concentrations has been correlated with cancer. A rise of intracellular Ca(2+) concentrations is also required for efficient CTL and NK cell function and thus for killing their targets, in this case cancer cells. Here, we review the data on Ca(2+)-dependent killing of cancer cells by CTL and NK cells. In addition, we discuss emerging ideas and present a model how Ca(2+) may be used by CTL and NK cells to optimize their cancer cell killing efficiency. This article is part of a Special Issue entitled: 12th European Symposium on Calcium. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Avian eggshell formation in calcium-rich and calcium-poor habitats: Importance of snail shells and anthropogenic calcium sources

    NARCIS (Netherlands)

    Graveland, J.

    1996-01-01

    Most passerines depend on the intake of calcium-rich material in addition to their normal food for proper eggshell formation and skeletal growth. A large proportion of Great Tits (Pants major) in forests on nutrient-poor soils in the Netherlands produce eggs with defective shells as a result of

  12. Electromagnetic fields act via activation of voltage-gated calcium channels to produce beneficial or adverse effects

    OpenAIRE

    Pall, Martin L

    2013-01-01

    The direct targets of extremely low and microwave frequency range electromagnetic fields (EMFs) in producing non-thermal effects have not been clearly established. However, studies in the literature, reviewed here, provide substantial support for such direct targets. Twenty-three studies have shown that voltage-gated calcium channels (VGCCs) produce these and other EMF effects, such that the L-type or other VGCC blockers block or greatly lower diverse EMF effects. Furthermore, the voltage-gat...

  13. Global LC/MS Metabolomics Profiling of Calcium Stressed and Immunosuppressant Drug Treated Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Stefan Jenkins

    2013-12-01

    Full Text Available Previous studies have shown that calcium stressed Saccharomyces cerevisiae, challenged with immunosuppressant drugs FK506 and Cyclosporin A, responds with comprehensive gene expression changes and attenuation of the generalized calcium stress response. Here, we describe a global metabolomics workflow for investigating the utility of tracking corresponding phenotypic changes. This was achieved by efficiently analyzing relative abundance differences between intracellular metabolite pools from wild-type and calcium stressed cultures, with and without prior immunosuppressant drugs exposure. We used pathway database content from WikiPathways and YeastCyc to facilitate the projection of our metabolomics profiling results onto biological pathways. A key challenge was to increase the coverage of the detected metabolites. This was achieved by applying both reverse phase (RP and aqueous normal phase (ANP chromatographic separations, as well as electrospray ionization (ESI and atmospheric pressure chemical ionization (APCI sources for detection in both ion polarities. Unsupervised principle component analysis (PCA and ANOVA results revealed differentiation between wild-type controls, calcium stressed and immunosuppressant/calcium challenged cells. Untargeted data mining resulted in 247 differentially expressed, annotated metabolites, across at least one pair of conditions. A separate, targeted data mining strategy identified 187 differential, annotated metabolites. All annotated metabolites were subsequently mapped onto curated pathways from YeastCyc and WikiPathways for interactive pathway analysis and visualization. Dozens of pathways showed differential responses to stress conditions based on one or more matches to the list of annotated metabolites or to metabolites that had been identified further by MS/MS. The purine salvage, pantothenate and sulfur amino acid pathways were flagged as being enriched, which is consistent with previously published

  14. Localization of calcium signals by a mobile calcium buffer in frog saccular hair cells.

    Science.gov (United States)

    Roberts, W M

    1994-05-01

    A recent study (Roberts, 1993) of saccular hair cells from grass frogs (Rana pipiens) has suggested a mechanism by which the unusually high concentrations of calcium-binding proteins found in certain sensory receptors and neurons, particularly in the auditory system, can influence short-range intracellular calcium signaling. In frog saccular hair cells, the mechanism operates within arrays of calcium channels and calcium-activated potassium channels that are involved in the cells' electrical resonance and synaptic transmission. The present study tests the hypothesis that calbindin-D28k, one of the most abundant proteins in these cells, can serve as a mobile calcium buffer that reduces and localizes changes in the intracellular free-calcium concentration ([Ca2+]i) by shuttling calcium away from the channel arrays. Based upon theoretical analysis and computer modeling, it is shown that [Ca2+]i near one or more open channels quickly reaches a steady-state level determined primarily by two properties of the buffer, the mean time (tau c) before it captures a free-calcium ion and a replenishment factor (R), which are related to the buffer's diffusional mobility (DBu), association rate constant (kon), and concentration (Bo) by tau c = (konB0)-1 and R = B0DBu. Simulation of calcium entry through a channel array showed that approximately 1.5 mM of a molecule with the diffusional and binding properties expected for calbindin-D28k (Bo approximately 8 mM calcium-binding sites) is needed to reproduce the previous experimental results. A lower concentration (B0 = 2 mM) was almost completely depleted within the channel array by a modest calcium current (8 pA = 12% of calcium channels open), but still had two important effects: it caused [Ca2+]i to fall steeply with distance outside the array (space constant < 50 nm), and returned [Ca2+]i quickly to the resting level after the channels closed. A high concentration of calbindin-D28k can thus influence the cell's electrical

  15. Effects of extracellular calcium on calcium transport during hyperthermia of tumor cells.

    Science.gov (United States)

    Anghileri, L J; Marcha, C; Crone-Escanyé, M C; Robert, J

    1985-08-01

    The effects of different concentrations of extracellular ion calcium on the transport of calcium by tumor cells have been studied by means of the uptake of radiocalcium. Tumor cells incubated at 45 degrees C take up 4-10 times the amount of radioactivity incorporated by cells incubated at 37 degrees C. The difference is still greater (up to 100 times) for the intracellular incorporation as assessed by elimination of the membrane-bound calcium by EGTA treatment. The possible mechanisms involved in this differential behavior are discussed.

  16. Antiproton production target of the AA

    CERN Multimedia

    Photographic Service; CERN PhotoLab

    1980-01-01

    The target rods were initially of tungsten, later of iridium. Diameters were around 3 mm and the lengths 60-110 mm. The rod is embedded in graphite, pressed into an aluminium body with cooling fins for forced air cooling. The 26 GeV proton beam from the PS was focused to the dimension of the rod. To aim precisely at its centre, the target was fitted with a scintillator screen, with circles at every 5 mm radius. Both scintillator and target had to stand pulses of 1.4E13 protons every 4.8 s, without interruption for many months.

  17. Precision nuclear targets for Drell-Yan cross section measurements at 800 GeV

    Science.gov (United States)

    Gursky, Judith C.; Baer, Helmut; Flick, Fred F.; Gallegos, Dan

    1989-10-01

    Targets of iron, tungsten, carbon, and calcium or areal densities 2.3-5.8 g/cm 2 were fabricated to high precision for a fixed-target experiment performed in 1987 at Fermilab to measure relative Drell-Yan cross sections. The experiment used 800-GeV protons at an intensity of 2 × 10 12 protons per 23-s spill. Areal densities were determined to an accuracy of approximately 1 part in 10 4. The calcium targets were vacuum-encapsulated in stainless steel by electron-beam welding.

  18. MEET ISOLDE - Target Production

    CERN Multimedia

    2017-01-01

    MEET ISOLDE - Target Production. Everything at ISOLDE starts with a target and the target production team realise on more then 50 years of experience to build and develop new targets for ISOLDE’s wide physics program.

  19. Simplified Citrate Anticoagulation for CRRT Without Calcium Replacement.

    Science.gov (United States)

    Broman, Marcus; Klarin, Bengt; Sandin, Karin; Carlsson, Ola; Wieslander, Anders; Sternby, Jan; Godaly, Gabriela

    2015-01-01

    Since 2012, citrate anticoagulation is the recommended anticoagulation strategy for continuous renal replacement therapy (CRRT). The main drawback using citrate as anticoagulant compared with heparin is the need for calcium replacement and the rigorous control of calcium levels. This study investigated the possibility to achieve anticoagulation while eliminating the need for calcium replacement. This was successfully achieved by including citrate and calcium in all CRRT solutions. Thereby the total calcium concentration was kept constant throughout the extracorporeal circuit, whereas the ionized calcium was kept at low levels enough to avoid clotting. Being a completely new concept, only five patients with acute renal failure were included in a short, prospective, intensely supervised nonrandomized pilot study. Systemic electrolyte levels and acid-base parameters were stable and remained within physiologic levels. Ionized calcium levels declined slightly initially but stabilized at 1.1 mmol/L. Plasma citrate concentrations stabilized at approximately 0.6 mmol/L. All postfilter ionized calcium levels were CRRT.

  20. Calcium and Iron Levels in Some Fruits and Vegetables Commonly ...

    African Journals Online (AJOL)

    , Cabbage, Pepper, Spinach, and Tomato) in each case were analysed for their Calcium and iron levels using spectrophotometric method of analysis; From the results, it was found that the concentration of Calcium was highest in spinach ...

  1. Calcium supplementation to prevent pre-eclampsia - a systematic ...

    African Journals Online (AJOL)

    Calcium supplementation to prevent pre-eclampsia - a systematic review. ... To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child adverse ... Article Metrics.

  2. The effect of farmyard manure and calcium ammonium nitrate ...

    African Journals Online (AJOL)

    The effect of farmyard manure and calcium ammonium nitrate fertilisers on micronutrient density (iron, zinc, manganese, calcium and potassium) and seed yields of solanium villosum (black nightshade) and cleome gynandra (cat whiskers) on uetric nitisol.

  3. Peanut (Arachis hypogaea L.) Cultivar Response to Prohexadione Calcium

    Science.gov (United States)

    Peanut digging efficiency can be reduced if row visibility is limited by excessive vegetation. The plant growth regulator prohexadione calcium retards vegetative growth and improves row visibility by inhibiting internode elongation. In some instances, prohexadione calcium also increases pod yield....

  4. Astrocyte calcium signalling orchestrates neuronal synchronization in organotypic hippocampal slices

    Science.gov (United States)

    Sasaki, Takuya; Ishikawa, Tomoe; Abe, Reimi; Nakayama, Ryota; Asada, Akiko; Matsuki, Norio; Ikegaya, Yuji

    2014-01-01

    Astrocytes are thought to detect neuronal activity in the form of intracellular calcium elevations; thereby, astrocytes can regulate neuronal excitability and synaptic transmission. Little is known, however, about how the astrocyte calcium signal regulates the activity of neuronal populations. In this study, we addressed this issue using functional multineuron calcium imaging in hippocampal slice cultures. Under normal conditions, CA3 neuronal networks exhibited temporally correlated activity patterns, occasionally generating large synchronization among a subset of cells. The synchronized neuronal activity was correlated with astrocyte calcium events. Calcium buffering by an intracellular injection of a calcium chelator into multiple astrocytes reduced the synaptic strength of unitary transmission between pairs of surrounding pyramidal cells and caused desynchronization of the neuronal networks. Uncaging the calcium in the astrocytes increased the frequency of neuronal synchronization. These data suggest an essential role of the astrocyte calcium signal in the maintenance of basal neuronal function at the circuit level. PMID:24710057

  5. Calcium Supplements: A Risk Factor for Heart Attack?

    Science.gov (United States)

    ... factor for heart attack? I've read that calcium supplements may increase the risk of heart attack. ... D. Some doctors think it's possible that taking calcium supplements may increase your risk of a heart ...

  6. Calcium Supplements: Do They Interfere with Blood Pressure Drugs?

    Science.gov (United States)

    ... with blood pressure drugs? Is it true that calcium supplements may interact with blood pressure medications? Answers ... G. Sheps, M.D. Yes. In large amounts, calcium supplements may interact with some blood pressure medications. ...

  7. PYK2: A Calcium-sensitive Protein Tyrosine Kinase Activated in Response to Fertilization of the Zebrafish Oocyte

    Science.gov (United States)

    Sharma, Dipika; Kinsey, William H.

    2012-01-01

    Fertilization begins with binding and fusion of a sperm with the oocyte, a process that triggers a high amplitude calcium transient which propagates through the oocyte and stimulates a series of preprogrammed signal transduction events critical for zygote development. Identification of the pathways downstream of this calcium transient remains an important step in understanding the basis of zygote quality. The present study demonstrates that the calcium-calmodulin sensitive protein tyrosine kinase PYK2 is a target of the fertilization-induced calcium transient in the zebrafish oocyte and that it plays an important role in actin-mediated events critical for sperm incorporation. At fertilization, PYK2 was activated initially at the site of sperm-oocyte interaction and was closely associated with actin filaments forming the fertilization cone. Later PYK2 activation was evident throughout the entire oocyte cortex, however activation was most intense over the animal hemisphere. Fertilization-induced PYK2 activation could be blocked by suppressing calcium transients in the ooplasm via injection of BAPTA as a calcium chelator. PYK2 activation could be artificially induced in unfertilized oocytes by injection of IP3 at concentrations sufficient to induce calcium release. Functionally, suppression of PYK2 activity by chemical inhibition or by injection of a dominant-negative construct encoding the N-terminal ERM domain of PKY2 inhibited formation of an organized fertilization cone and reduced the frequency of successful sperm incorporation. Together, the above findings support a model in which PYK2 responds to the fertilization-induced calcium transient by promoting reorganization of the cortical actin cytoskeleton to form the fertilization cone. PMID:23084926

  8. Functional and pharmacological consequences of the distribution of voltage-gated calcium channels in the renal blood vessels.

    Science.gov (United States)

    Hansen, P B L

    2013-04-01

    Calcium channel blockers are widely used to treat hypertension because they inhibit voltage-gated calcium channels that mediate transmembrane calcium influx in, for example, vascular smooth muscle and cardiomyocytes. The calcium channel family consists of several subfamilies, of which the L-type is usually associated with vascular contractility. However, the L-, T- and P-/Q-types of calcium channels are present in the renal vasculature and are differentially involved in controlling vascular contractility, thereby contributing to regulation of kidney function and blood pressure. In the preglomerular vascular bed, all the three channel families are present. However, the T-type channel is the only channel in cortical efferent arterioles which is in contrast to the juxtamedullary efferent arteriole, and that leads to diverse functional effects of L- and T-type channel inhibition. Furthermore, by different mechanisms, T-type channels may contribute to both constriction and dilation of the arterioles. Finally, P-/Q-type channels are involved in the regulation of human intrarenal arterial contractility. The calcium blockers used in the clinic affect not only L-type but also P-/Q- and T-type channels. Therefore, the distinct effect obtained by inhibiting a given subtype or set of channels under experimental settings should be considered when choosing a calcium blocker for treatment. T-type channels seem to be crucial for regulating the GFR and the filtration fraction. Use of blockers is expected to lead to preferential efferent vasodilation, reduction of glomerular pressure and proteinuria. Therefore, renovascular T-type channels might provide novel therapeutic targets, and may have superior renoprotective effects compared to conventional calcium blockers. Acta Physiologica © 2013 Scandinavian Physiological Society.

  9. Beyond-root calcium fertilization of apple trees

    Directory of Open Access Journals (Sweden)

    Kazimierz Słowik

    2013-12-01

    Full Text Available Investigations were performed in the period 1977-1979 on the apple tree cultivar 'Fantazja', on rootstock A 2, M 7 and MM 106 on the effect of spraying with solution containing calcium on the incidence of bitter pit, breakdown, calcium content in the fruit flesh and other features of the fruits. Threefold spraying with calcium nitrate, calcium chloride or Anti-Stipp significantly limited the appearance of bitter pit and breakdown.

  10. Calcium Intake in Elderly Australian Women Is Inadequate

    Directory of Open Access Journals (Sweden)

    Colin W. Binns

    2010-09-01

    Full Text Available The role of calcium in the prevention of bone loss in later life has been well established but little data exist on the adequacy of calcium intakes in elderly Australian women. The aim of this study was to compare the dietary intake including calcium of elderly Australian women with the Australian dietary recommendation, and to investigate the prevalence of calcium supplement use in this population. Community-dwelling women aged 70–80 years were randomly recruited using the Electoral Roll for a 2-year protein intervention study in Western Australia. Dietary intake was assessed at baseline by a 3-day weighed food record and analysed for energy, calcium and other nutrients. A total of 218 women were included in the analysis. Mean energy intake was 7,140 ± 1,518 kJ/day and protein provided 19 ± 4% of energy. Mean dietary calcium intake was 852 ± 298 mg/day, which is below Australian recommendations. Less than one quarter of women reported taking calcium supplements and only 3% reported taking vitamin D supplements. Calcium supplements by average provided calcium 122 ± 427 mg/day and when this was taken into account, total calcium intake increased to 955 ± 504 mg/day, which remained 13% lower than the Estimated Average Requirement (EAR, 1,100 mg/day for women of this age group. The women taking calcium supplements had a higher calcium intake (1501 ± 573 mg compared with the women on diet alone (813 ± 347 mg. The results of this study indicate that the majority of elderly women were not meeting their calcium requirements from diet alone. In order to achieve the recommended dietary calcium intake, better strategies for promoting increased calcium, from both diet and calcium supplements appears to be needed.

  11. Modulation of L-type calcium channels by sodium ions.

    OpenAIRE

    Balke, C W; Wier, W G

    1992-01-01

    It is universally believed that the removal of external sodium ions is without effect on calcium current. We now report that in enzymatically isolated guinea pig ventricular cells, the replacement of external sodium ions with certain other cations causes a 3- to 6-fold increase in peak L-type calcium current. The increase in current is reversibly blocked by L-type calcium-channel antagonists, not mediated by changes in internal calcium, and is inhibited by intracellular 5'-adenylyl imidodipho...

  12. How calcium makes endocytic receptors attractive

    DEFF Research Database (Denmark)

    Andersen, Christian B F; Moestrup, Søren K

    2014-01-01

    'lynchpin' that stabilizes favorable positioning of ligand-attractive receptor residues. In addition to explaining how calcium depletion can cause ligand-receptor dissociation, the new data add further insight into how acidification contributes to dissociation through structural changes that affect...

  13. Drying and Rehydration of Calcium Alginate Gels

    NARCIS (Netherlands)

    Vreeker, R.; Li, L.; Fang, Y.; Appelqvist, I.; Mendes, E.

    2008-01-01

    In this paper, we study the rehydration properties of air-dried calcium alginate gel beads. Rehydration is shown to depend on alginate source (i.e. mannuronic to guluronic acid ratio) and the salt concentration in the rehydration medium. Rehydration curves are described adequately by the empirical

  14. Pharmacological analysis of calcium antagonist receptors

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, I.J.

    1987-01-01

    This work focuses on two aspects of the action of calcium antagonist drugs, namely, the interaction of drugs with receptors for verapamil-like calcium antagonists, and the interactions of drugs with voltage-sensitive calcium fluxes in rat brain synaptosomes. From binding studies I have found that the ligand of choice for labeling the verapamil receptor is (-)(/sup 3/H)desmethoxy-verapamil. This drug labels potently, reversibly and stereoselectively two receptors in membranes prepared from rat brain and rabbit skeletal muscle tissues. In equilibrium studies dihydropyridine calcium antagonists interact in a non-competitive fashion, while many non-DHPs are apparently competitive. In-depth kinetic studies in skeletal muscle membranes indicate that the two receptors are linked in a negative heterotropic fashion, and that low-affinity binding of (-) (/sup 3/H)desmethoxy-verapamil may be to the diltiazem receptor. However, these studies were not able to distinguish between the hypothesis that diltiazem binds to spatially separate, allosterically coupled receptors, and the hypothesis that diltiazem binds to a subsite of the verapamil receptor.

  15. Physicochemical characterization of zinc-substituted calcium ...

    Indian Academy of Sciences (India)

    On the contrary, no changes of the crystallinity were observed for the brushite doped with Zn ions. Morphology of attained powders, visualized using scanningelectron microscopy exemplified structural changes between calcium phosphates conjugated with zinc ions. Many authors report that the addition of small amounts of ...

  16. Simulating cement microstructural evolution during calcium leaching

    NARCIS (Netherlands)

    Patel, R.A.; Perko, J.; Jacques, D.; De Schutter, G.; Van Breugel, K.; Ye, G.

    2014-01-01

    Calcium leaching is one of the important degradation mechanisms causing dissolution of the crystalline phases such as, AFm, portlandite increasing capillary porosity. Further it leads to decalcification of an amorphous C-S-H phase causing increase in the gel porosity and in turn degrading the long

  17. Serum Calcium, Inorganic Phosphates and some Haematological ...

    African Journals Online (AJOL)

    Objectives: Sickle cell disease has long been associated with bone deformities and pain. Mineral salts such as calcium and inorganic phosphate are critical in bone formation and metabolism. This investigation was designed to study the serum concentration of these minerals as well as some haematological parameters in ...

  18. 21 CFR 582.5217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.5217 Section 582.5217 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. 21 CFR 582.5210 - Calcium oxide.

    Science.gov (United States)

    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 Supplements...

  20. 21 CFR 582.5223 - Calcium pyrophosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium pyrophosphate. 582.5223 Section 582.5223 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...

  1. 21 CFR 582.5212 - Calcium pantothenate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium pantothenate. 582.5212 Section 582.5212 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...

  2. 21 CFR 582.5230 - Calcium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium sulfate. 582.5230 Section 582.5230 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...

  3. 21 CFR 582.5195 - Calcium citrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium citrate. 582.5195 Section 582.5195 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...

  4. 21 CFR 582.5201 - Calcium glycerophosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium glycerophosphate. 582.5201 Section 582.5201 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...

  5. CALCIUM DEFICIENCY AND CAUSATION OF RICKETS IN ...

    African Journals Online (AJOL)

    hi-tech

    2005-03-03

    Mar 3, 2005 ... Objective: To assess the role of calcium in the development of clinical rickets among. Ethiopian children coming to Jimma Specialised Hospital outpatient, department. Design: Case control study. Settings: Jimma Specialised Teaching Hospital and surrounding urban and rural community in the catchment ...

  6. An improved calcium chloride method preparation and ...

    African Journals Online (AJOL)

    In this paper, we have reported a modified method for preparation and transformation of competent cells. This modified method, improved from a classical protocol, has made some modifications on the concentration of calcium chloride and competent bacteria solution, rotation speed in centrifugation and centrifugation time.

  7. Biocompatibility of bio based calcium carbonate nanocrystals ...

    African Journals Online (AJOL)

    Material and Methods: Transmission and field emission scanning electron microscopy (TEM and FESEM) were used for the characterisation of CaCO3 nanocrystals. Cytotoxicity and genotoxic effect of calcium carbonate nanocrystals in cultured mouse embryonic fibroblast NIH 3T3 cell line using various bioassays including ...

  8. Calcium carbonate precipitation by different bacterial strains ...

    African Journals Online (AJOL)

    Bacteria are capable of performing metabolic activities which thereby promote precipitation of calcium carbonate in the form of calcite. In this study, it is shown that microbial mineral precipitation was a result of metabolic activities of some specific microorganisms. Concrete microorganisms were used to improve the overall ...

  9. Fabrication and Evaluation of Rosuvastatin Calcium Fast ...

    African Journals Online (AJOL)

    Available online at http://www.tjpr.org · http://dx.doi.org/10.4314/tjpr.v14i11.2. Original ... Revised accepted: 6 October 2015. Abstract. Purpose: To formulate fast-disintegrating tablets (FDT) of rosuvastatin calcium (RST) using β- ... promote dissolution, absorption and ultimately bioavailability thereby reducing particle size or.

  10. Calcium enhances cadmium tolerance and decreases cadmium ...

    African Journals Online (AJOL)

    These results suggest that cadmium uptake in lettuce plants is negatively associated with the presence of calcium in the culture medium, maybe due to a competition between these two cations for binding and absorption sites in roots. In conclusion, the results suggest that fertilization with Ca2+ appears to be a promising ...

  11. Osteophagia provide giraffes with phosphorus and calcium?

    Science.gov (United States)

    Bredin, I P; Skinner, J D; Mitchell, G

    2008-03-01

    The daily requirement for calcium and phosphorus by giraffes to sustain the growth and maintenance of their skeletons is large. The source of sufficient calcium is browse. The source of necessary phosphorus is obscure, but it could be osteophagia, a frequently observed behaviour in giraffes. We have assessed whether bone ingested as a result of osteophagia can be digested in the rumen. Bone samples from cancellous (cervical vertebrae) and dense bones (metacarpal shaft) were immersed in the rumens of five sheep, for a period of up to 30 days, and the effect compared to immersion in distilled water and in artificial saliva for 30 days. Distilled water had no effect on the bones. Dense bone samples were softened by exposure to the saliva and rumen fluid, but did not lose either calcium or phosphorus. In saliva and rumen fluid the cancellous bone samples also softened, and their mass and volume decreased as a result of exposure to saliva, but in neither fluid did they lose significant amounts of calcium and phosphorus. We conclude that although saliva and rumen fluid can soften ingested bones, there is an insignificant digestion of bones in the rumen.

  12. [Intra-cystic renal calcium milk].

    Science.gov (United States)

    Meunier, B; Médart, L; Massart, J P; Collignon, L

    2015-02-01

    Intra-cystic renal calcium milk is a rare entity. The authors report a clinical case, and describe the radiographic and tomodensitometric appearances. This 50 year old patient has been followed up for more than ten years for urinary lithiasis with recurrent pain.

  13. Isolation and characterization of biogenic calcium carbonate ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 2. Isolation and characterization of biogenic calcium carbonate/phosphate from oral bacteria and their adhesion studies on YSZ-coated titanium substrate for dental implant application. GOBI SARAVANAN KALIARAJ KAMALAN KIRUBAHARAN G ...

  14. Effect of Ultrasound on Calcium Carbonate Crystallization

    NARCIS (Netherlands)

    Wagterveld, R.M.

    2013-01-01

    Scaling comprises the formation of hard mineral deposits on process or membrane equipment and calcium carbonate is the most common scaling salt. Especially in reverse osmosis (RO) membrane systems, scale formation has always been a serious limitation, causing flux decline, membrane degradation, loss

  15. Exploring the calcium isotope signature of

    NARCIS (Netherlands)

    Hippler, D.; Witbaard, R.; van Aken, H.M.; Buhl, D.; Immenhauser, A.

    2013-01-01

    The calcium-isotope composition (delta Ca-44/40) of the aragonitic bivalve Arctica islandica grown in laboratory and field cultures was investigated in terms of environmental and biological controls to explore its potential as a palaeoceanographic proxy. While we found no significant effect of

  16. Thermoluminescence dosimetry of rare earth doped calcium ...

    Indian Academy of Sciences (India)

    The thermoluminescence (TL) properties of calcium aluminate (CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of ...

  17. An in vitro Comparison of Endodontic Medicaments Propolis and Calcium Hydroxide alone and in Combination with Ciprofloxacin and Moxifloxacin against Enterococcus Faecalis.

    Science.gov (United States)

    Shrivastava, Rahul; Rai, Vivek Kumar; Kumar, Aina; Sinha, Sonal; Tripathi, Prerna; Gupta, Khushboo; Sabharwal, Sumit

    2015-05-01

    To evaluate and compare the antimicrobial properties of propolis and calcium hydroxide alone and in combination with ciprofloxacin and moxifloxacin against Enterococcus faecalis (E. Faecalis). The laboratory study was carried out to test the effectiveness of propolis and calcium hydroxidealone as well as in combination with the established endodontic medicaments (moxifloxacin and ciprofloxacin). The various combinations were-group 1: propolis, group 2: calcium hydroxide, group 3: moxifloxacin, group 4: ciprofoxacin, group 5: propolis + moxifloxacin, group 6: propolis + Ciprofloxacin, group 7: calcium hydroxide + ciprofloxacin, group 8: calcium hydroxide + moxifloxacin. The efficacy of these medicaments was tested by checking for the zone of inhibition for the specific strain (ATCC 29212) of E. faecalis at different time intervals, i.e. 24, 48 and 72 hours. Mean zone of inhibition was maximum in group V (21.94 ± 4.26) followed by group VI (18.80 ± 1.93), group I (18.71 ± 4.26), group VIII (15.88 ± 2.59), group III (14.91 ± 1.00), group VII (14.57 ± 2.17), group IV (13.91 ± 1.00) and minimum in group II (12.89 ± 2.14). Mean zone of inhibition was found to be maximum at 72 hours and minimum at 24 hours. At all time intervals, the combination of Propalis with Moxifocacin showed the maximum antimicrobial efficacy. On the basis of the results of the present study, it can be concluded that propolis and calcium hydroxide show synergistic effect with moxifloxacin and ciprofloxacin against E. Faecalis. Propolis in combination with antibiotics and alone is more effective than calcium hydroxide. Since propolis alone and in combination with antibiotics was observed to be more effective than calcium hydroxide, propolis can be considered as an intracanal medicament when compared to traditional calcium hydroxide.

  18. Role of AtCDC48 & the AtCDC48 Regulatory Protein Family, PUX, in Plant Cell Morphogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Bednarek, Sebastian, Y.

    2009-11-08

    The long-term objective of this work is to understand the molecular events and mechanisms involved in secretory membrane trafficking and organelle biogenesis, which are crucial for normal plant growth and development. Our studies have suggested a vital role for the cytosolic chaperone Cdc48p/p97 during cytokinesis and cell expansion which are highly dependent upon secretory membrane trafficking. Localization studies have shown that the plant Cdc48p/p97, AtCDC48, and the Arabidopsis ortholog of the ER- and Golgi-associated SNARE, syntaxin 5, (referred to as SYP31) are targeted to the division plane during cytokinesis. In addition, AtCDC48 and SYP31 were shown to interact in vitro and in vivo. To characterize further the function of AtCDC48 and SYP31 we have utilized affinity chromatography and MALDI-MS to identify several plant-specific proteins that interact with SYP31 and/or modulate the activity of AtCDC48 including two UBX (i.e. ubiquitin-like) domain containing proteins, PUX1 and PUX2 (Proteins containing UBX domain). These proteins define a plant protein family consisting of 15 uncharacterized members that we postulate interact with AtCDC48. Biochemical studies have demonstrated that PUX2 is a novel membrane adapter for AtCDC48 that mediates AtCDC48/SYP31 interaction and is likely to control AtCDC48-dependent membrane fusion. In contrast, PUX1 negatively regulates AtCDC48 by inhibiting its ATPase activity and by promoting the disassembly of the active hexamer. These findings provide the first evidence that the assembly and disassembly of the CDC48/p97complex is actually a dynamic process. This new unexpected level of regulation for CDC48/p97 was demonstrated to be critical in vivo as pux1 loss-of-function mutants grow faster than wild-type plants. These studies suggest a role for AtCDC48 in plant cell cycle progression including cytokinesis and/or cell expansion. The proposed studies are designed to: 1) characterize further the localization and function of At

  19. Altered calcium metabolism: the probable major biochemical lesion ...

    African Journals Online (AJOL)

    These data are suggestive of altered calcium metabolism impairing cell membrane stabilization, the vasorelaxing effect of calcium and cell signaling. Altered calcium metabolism may be the major biochemical lesion underlying many pathological and clinical states of lead toxicity. Journal of Biomedical Investigation Vol.

  20. Dietary calcium intake and sunlight exposure among children aged ...

    African Journals Online (AJOL)

    Nutritional rickets can be caused by either or both calcium and vitamin D deficiencies, and can frequently occur in Africa. In Ethiopia, limited evidence exists regarding the calcium intake of children and their sunlight exposure practices. The purpose of this study was to assess information regarding dietary calcium intake and ...