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Sample records for calcium complexes

  1. Membrane associated complexes in calcium dynamics modelling

    International Nuclear Information System (INIS)

    Mitochondria not only govern energy production, but are also involved in crucial cellular signalling processes. They are one of the most important organelles determining the Ca2+ regulatory pathway in the cell. Several mathematical models explaining these mechanisms were constructed, but only few of them describe interplay between calcium concentrations in endoplasmic reticulum (ER), cytoplasm and mitochondria. Experiments measuring calcium concentrations in mitochondria and ER suggested the existence of cytosolic microdomains with locally elevated calcium concentration in the nearest vicinity of the outer mitochondrial membrane. These intermediate physical connections between ER and mitochondria are called MAM (mitochondria-associated ER membrane) complexes. We propose a model with a direct calcium flow from ER to mitochondria, which may be justified by the existence of MAMs, and perform detailed numerical analysis of the effect of this flow on the type and shape of calcium oscillations. The model is partially based on the Marhl et al model. We have numerically found that the stable oscillations exist for a considerable set of parameter values. However, for some parameter sets the oscillations disappear and the trajectories of the model tend to a steady state with very high calcium level in mitochondria. This can be interpreted as an early step in an apoptotic pathway. (paper)

  2. Complex formation ions calcium with macromolecules pectin

    International Nuclear Information System (INIS)

    In clause the mechanism of sorption of ions of calcium by macromolecules of pectin is opened. Is shown, that the linkage of ions of calcium descends on acid bunches of pectin, and process carries cooperative character

  3. Stability analysis for complexes in calcium-alkali bromide solutions

    International Nuclear Information System (INIS)

    We discuss the dependence of the stability of tetrahedral complexes in molten halide mixtures on the halogen species. This is done by calculating the equilibrium concentration of (CaBr4)2- complexes in calcium-alkali bromide solutions as a function of composition, in comparison with earlier calculations on the calcium-alkali chloride systems. The comparison supports a possible trend of increasing stability from chlorides to bromides, provided that halogen polarizability or chemical bonding contribute appreciably to the binding of a complex. Supporting evidence is noted and further experiments are suggested. (author). 10 refs, 2 figs

  4. 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. PMID:26455959

  5. Multilevel complexity of calcium signaling:Modeling angiogenesis

    Institute of Scientific and Technical Information of China (English)

    Luca; Munaron; Marco; Scianna

    2012-01-01

    Intracellular calcium signaling is a universal,evolutionary conserved and versatile regulator of cell biochemistry.The complexity of calcium signaling and related cell machinery can be investigated by the use of experimental strategies,as well as by computational approaches.Vascular endothelium is a fascinating model to study the specific properties and roles of calcium signals at multiple biological levels.During the past 20 years,live cell imaging,patch clamp and other techniques have allowed us to detect and interfere with calcium signaling in endothelial cells(ECs),providing a huge amount of information on the regulation of vascularization(angiogenesis) in normal and tumoral tissues.These data range from the spatiotemporal dynamics of calcium within different cell microcompartments to those in entire multicellular and organized EC networks.Beside experimental strategies,in silico endothelial models,specifically designed for simulating calcium signaling,are contributing to our knowledge of vascular physiol-ogy and pathology.They help to investigate and predict the quantitative features of proangiogenic events moving through subcellular,cellular and supracellular levels.This review focuses on some recent developments of computational approaches for proangiogenic endothelial calcium signaling.In particular,we discuss the creation of hybrid simulation environments,which combine and integrate discrete Cellular Potts Models.They are able to capture the phenomenological mechanisms of cell morphological reorganization,migration,and intercellular adhesion,with single-cell spatiotemporal models,based on reaction-diffusion equations that describe the agonist-induced intracellular calcium events.

  6. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes

    International Nuclear Information System (INIS)

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H3PO4/P2O5/Et3PO4 followed by acid–base reaction with Ca(OAc)2 to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for 1H, and 31P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2 w/v%) with NaAlg solution (2 w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO4 or CaCl2 were added externally. The gelation was completed within about 3–40 min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤ 6.7 kPa for compressive strength at break and about 8.4 kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100–800 μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering. - Highlights: • Preparation of water-soluble alginic acid complexes with calcium phosphate • Self-assembly of the phosphorylated alginic acid calcium complexes with sodium alginate • Preparation of injectable hydrogels with diverse gelation times within about 3–40 min

  7. Cardiac voltage-gated calcium channel macromolecular complexes.

    Science.gov (United States)

    Rougier, Jean-Sébastien; Abriel, Hugues

    2016-07-01

    Over the past 20years, a new field of research, called channelopathies, investigating diseases caused by ion channel dysfunction has emerged. Cardiac ion channels play an essential role in the generation of the cardiac action potential. Investigators have largely determined the physiological roles of different cardiac ion channels, but little is known about the molecular determinants of their regulation. The voltage-gated calcium channel Cav1.2 shapes the plateau phase of the cardiac action potential and allows the influx of calcium leading to cardiomyocyte contraction. Studies suggest that the regulation of Cav1.2 channels is not uniform in working cardiomyocytes. The notion of micro-domains containing Cav1.2 channels and different calcium channel interacting proteins, called macro-molecular complex, has been proposed to explain these observations. The objective of this review is to summarize the currently known information on the Cav1.2 macromolecular complexes in the cardiac cell and discuss their implication in cardiac function and disorder. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel. PMID:26707467

  8. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-Sem; Song, Minsoo, E-mail: minsoosong00@gmail.com; Lee, Eun-Jung; Shin, Ueon Sang, E-mail: usshin12@dankook.ac.kr

    2015-06-01

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H{sub 3}PO{sub 4}/P{sub 2}O{sub 5}/Et{sub 3}PO{sub 4} followed by acid–base reaction with Ca(OAc){sub 2} to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for {sup 1}H, and {sup 31}P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2 w/v%) with NaAlg solution (2 w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO{sub 4} or CaCl{sub 2} were added externally. The gelation was completed within about 3–40 min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤ 6.7 kPa for compressive strength at break and about 8.4 kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100–800 μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering. - Highlights: • Preparation of water-soluble alginic acid complexes with calcium phosphate • Self-assembly of the phosphorylated alginic acid calcium complexes with sodium alginate • Preparation of injectable hydrogels with diverse gelation times within about 3–40 min.

  9. Infrared Spectroscopic Characterization of Calcium and Barium Hydrazone Complexes

    Directory of Open Access Journals (Sweden)

    *A. Adeniyi

    2013-06-01

    Full Text Available Hydrazones have attracted considerable interest on account of their biological activities. Introduction of calcium and barium metal ions into m- and p-nitrobenzoic hydrazones is expected to modify these biological properties for enhanced activity and versatility. The ligands were synthesized from the parent acids. The complexes have been characterized using C, H and N microanalyses and IR spectrometry. The IR spectral data of the ligands and complexes revealed bonding via the C=O and C=N groups. The suggested metal to ligand stoichiometries are: [M (m-NBHx]Cl2.yH2O, x, y = 1 and 4 for M = Ca; x, y = 2 and 3 for M = Ba respectively. [M(p-NBHx]Cl2.yH2O, x, y = 1 and 12 for M = Ca; x, y = 1 and 3 for M = Ba respectively. The structural deductions are tentative pending future X-ray structural studies.

  10. 13C nuclear magnetic resonance study of the complexation of calcium by taurine

    International Nuclear Information System (INIS)

    13C Nuclear magnetic resonance chemical shifts, 1J/sub c-c/ scalar coupling constants, spin-lattice relaxation times, and nuclear Overhauser effects were determined for taurine-[1, 2 13C] and a taurine-[1 13C] and taurine-[2 13C] mixture in the presence and absence of calcium. Comparison of taurine titration shifts to values for related compounds reveals some unusual electronic properties of the taurine molecule. Stability constants of 1:1 calcium complexes with taurine zwitterions and anions, as well as their 13C chemical shifts, were obtained by least squares analysis of titration curves measured in the presence of calcium. The stability constants of calcium-taurine complexes were significantly lower than previous values and led to estimates that only approximately one percent of intracellular calcium of mammalian myocardial cells would exist in a taurine complex

  11. Complex formation of calcium with humic acid and polyacrylic acid

    International Nuclear Information System (INIS)

    In order to understand the migration behavior of radionuclides in the underground, it is also important to estimate the effect of the competing cations originally present in the groundwater. In this connection, the complexation of Ca(II) with Aldrich humic acid has been examined. For the study at trace concentrations (∝ 10-10 M) of Ca(II), the solvent extraction of 45Ca with TTA and TOPO in cyclohexane has been used. At macro concentrations (10-4 M) of Ca(II), the measurement of the free Ca2+ ion concentration with a calcium selective electrode has been conducted. To estimate the polyelectrolyte effect of humic acid separately from its heterogeneous composition effect, polyacrylic acid ([-CH2CH(COOH)-]n) has been selected as a representative of the homogeneous polymeric weak acids and its complexation with Ca(II) has also been examined. The values of log βα have been obtained at pH 5 ∝ 7 in 0.1, 0.4 and 1.0 M NaCl, where βα is the apparent formation constants defined by βα = [ML]/([M][R]). In this definition, [ML] and [M] are the concentrations of bound and free Ca2+ respectively, [R] is the concentration of dissociated proton exchanging sites. log βα of humate decreases from 2.19 ∝ 2.92 (depending on pH and ionic strength 1.0 α of polyacrylate (1.36 ∝ 3.24 for I = 0.1 ∝ 1.0). For both humate and polyacrylate, log βα decreases linearly with log[Na+], where [Na+] is the bulk concentration of sodium ion. Their dependences of log βα on ionic strength are stronger than those of log β of monomeric carboxylates such as oxalate and EDTA, indicating the large electrostatic effect of crowded negative charges on the macromolecules of humic or polyacrylic acid. (orig.)

  12. Potentiometric study on the complexation of calcium with some humic and fulvic acids - dependence of the interaction on calcium concentration

    International Nuclear Information System (INIS)

    Full text of publication follows: Humic substances are found as heterogeneous mixtures of organic macromolecular colloids even in deep underground environments used for the geological disposal of radioactive wastes and affect the migration behavior of radionuclides by forming complexes. The presence of higher concentrations of naturally-existing cations such as calcium and iron may affect their interaction with radionuclides. For example, the formation of pseudo-colloidal complexes of radionuclides may be suppressed by the formation of calcium humate complexes or the excess amount of calcium may promote the precipitation of the humate colloids. Thus, to understand and estimate the migration behavior of radionuclides in the presence of naturally-existing cations, it is essential to quantitatively describe the interaction of both radionuclides and naturally-existing cations in a wide range of their concentrations. In our previous study [1], we have proposed the very simplified expression to describe the interaction of humic substances with metal ions, log Kapp log K + a logα - b log[Na+] - m log[M] for Kapp = [ML]/([M][R]), where [ML] and [M] are the concentrations of bound and free metal ion, [R] is that of dissociated proton exchange site and a is the degree of dissociation (charges are omitted). However, since the expression has been derived from the limited experimental observations, the serious concern remained unresolved, that is, the relation of log Kapp to the metal ion concentration (the independence of m on log α) was not well examined. To check this point, the complexation of calcium was studied by potentiometry. Four kinds of humic and fulvic acids obtained from International Humic Substance Society were titrated by NaOH in the absence and presence of various total concentrations of calcium in 0.01 M NaNO3 solution. In the procedure, both pcH (= -log[H+]) and log[Ca2+] were simultaneously measured with glass and ion-selective electrodes. From the

  13. Calcium-acidic phospholipid-phosphate complexes in human hydroxyapatite-containing pathologic deposits.

    OpenAIRE

    Boskey, A. L.; Bullough, P. G.; Vigorita, V.; Di Carlo, E

    1988-01-01

    The deposition of calcium-containing crystals in tissues is due to a combination of factors: elevation in the concentrations of precipitating ions, formation of specific nucleators, and removal of macromolecules that inhibit crystal deposition. This study tested the hypothesis that calcium acidic phospholipid phosphate complexes, which promote hydroxyapatite deposition both in vitro and in vivo, are associated only with hydroxyapatite deposits, and furthermore, that the presence of these comp...

  14. [K-strophanthin-beta complexing with calcium, magnesium and dysprosium ions].

    Science.gov (United States)

    Chekman, I S; Budarin, L I; Gorchakova, N A; Suchkova, R V; Tishura, T A

    1978-01-01

    Nuclear magnetic resonance, microcalorimetry and the use of the ion-selecting electrode evidenced that k-strophanthine-beta forms complexes with the calcium, magnesium and disprosium ions. Changes in the position of the k-strophanthine-beta carbohydrate parts and aglycones signals bear witness to their participation in the complexing. PMID:700079

  15. Calcium Oscillations

    OpenAIRE

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlyin...

  16. Transition in complex calcium bursting induced by IP3 degradation

    International Nuclear Information System (INIS)

    Complex intracellular Ca2+ oscillations are systematically investigated in a mathematical model based on the mechanism of Ca2+-induced Ca2+ release (CICR), taking account of the Ca2+-stimulated degradation of inositol 1,4,5-trisphosphate (IP3) by a 3-kinase. Periodic, quasi-periodic and chaotic bursting oscillations exist in a wide range of parameter values and occur alternatively as the parameters change slightly. The transition among them can be observed by the evidence in their interspike interval and the Lyapunov exponent. These results reveal the role of agonist-stimulated of IP3 degradation as a possible source for complex patterns in Ca2+ signaling.

  17. Studying microstructure and phase composition of a new complex calcium containing alloy

    Directory of Open Access Journals (Sweden)

    I. Bartenev

    2016-10-01

    Full Text Available In the given article there are presented the results of studying the microstructure and phase structure of a complex alloy of alumosilicon with calcium. It is established that in the studied CAMS alloy active elements are present at a type of difficult intermetallid that positively influences quality of both ordinary, and qualitative brands of steel.

  18. Transient Receptor Potential Channel 1 (TRPC1) Reduces Calcium Permeability in Heteromeric Channel Complexes

    Science.gov (United States)

    Storch, Ursula; Forst, Anna-Lena; Philipp, Maximilian; Gudermann, Thomas; Mederos y Schnitzler, Michael

    2012-01-01

    Specific biological roles of the classical transient receptor potential channel 1 (TRPC1) are still largely elusive. To investigate the function of TRPC1 proteins in cell physiology, we studied heterologously expressed TRPC1 channels and found that recombinant TRPC1 subunits do not form functional homomeric channels. Instead, by electrophysiological analysis TRPC1 was shown to form functional heteromeric, receptor-operated channel complexes with TRPC3, -4, -5, -6, and -7 indicating that TRPC1 proteins can co-assemble with all members of the TRPC subfamily. In all TRPC1-containing heteromers, TRPC1 subunits significantly decreased calcium permeation. The exchange of select amino acids in the putative pore-forming region of TRPC1 further reduced calcium permeability, suggesting that TRPC1 subunits contribute to the channel pore. In immortalized immature gonadotropin-releasing hormone neurons endogenously expressing TRPC1, -2, -5, and -6, down-regulation of TRPC1 resulted in increased calcium permeability and elevated basal cytosolic calcium concentrations. We did not observe any involvement of TRPC1 in store-operated cation influx. Notably, TRPC1 suppressed the migration of gonadotropin-releasing hormone neurons without affecting cell proliferation. Conversely, in TRPC1 knockdown neurons, specific migratory properties like distance covered, locomotion speed, and directionality were increased. These findings suggest a novel regulatory mechanism relying on the expression of TRPC1 and the subsequent formation of heteromeric TRPC channel complexes with reduced calcium permeability, thereby fine-tuning neuronal migration. PMID:22157757

  19. Filler modification for papermaking with starch/oleic acid complexes with the aid of calcium ions.

    Science.gov (United States)

    Huang, Xiujie; Shen, Jing; Qian, Xueren

    2013-10-15

    To mitigate the negative effect of filler addition on paper strength and improve filler retention, filler modification with hydrogen bonding polymers (e.g., starch) or their composites is an interesting research topic. Differing from previous reports, the concept related to the deposition of starch/oleic acid complexes on precipitated calcium carbonate (PCC) with the aid of calcium ions was demonstrated. The introduction of calcium ions resulted in effective starch deposition. As a result of filler modification, filler retention and the tensile strength of the filled paper were simultaneously improved essentially due to the aggregation of PCC particles in filler modification process as well as improved filler bondability. The concept demonstrated in this brief study may provide an alternative approach to filler bondability enhancement for improved papermaking performances. PMID:23987430

  20. Study on the complexation of humic substances with calcium ion by ion selective electrode method

    International Nuclear Information System (INIS)

    Introduction: Humic substances (HS), which are one of main organic components in soil and aquatic environment, can influence the migration and fate of nuclides through formation of complexes. To quantitatively describe such complex formation, it is essential to consider the formation of major dissolved constituents ions, such as alkali or alkali earth ions, with HSUI. This paper reports the result on the study of the complex formation of calcium ion with soil HS and polyacrylic acid, where polyacrylic acid is selected to observed the effect of heterogeneous composition of HS. Experimental: As an initial solution for the titration experiment, the fixed amounts of calcium ion, NaNO3 solution and HS or PAA were mixed in a 150 mL plastic bottle, which was covered with Laboatory Film (Parafilm 'M'). Then, a fixed amount of NaOH solution was added step by step and the concentration of calcium ion and pH in solution were measured (IM-40S ion meter, DKK.TOA CORP. Japan) simultaneously after each addition. All the experiments were conducted in the 0.01 mol/L NaNO3 solution at 298.2 K in temperature under Ar atmosphere. The humic substances, Elliott soil humic acid (HA) (Cat.No.1sl02H) and Elliott soil Fulvic acid (FA) (Cat.No. lsl02H ), were obtained from International Humic Substances Society(IHSS). Polyacrylic acids (PAA) were obtained from polyscience Inc.(M.W. ca. 450.000). The other chemicals are of analytical grade. De-ionized water (Milli-Q Pureline, Yamato, Japan) was used to prepare the solution. Results and discussion: Fig. 1. shows tile typical titration curves of 500 mg/L HA containing 0.00, 6.24, 20.4, 41.6 mg/L total calcium ion in 0.010 mol/L NaN3 at 298.2 K under Ar atmosphere. The differences between the titration curves of the solution with and without calcium ion indicate the formation of complex with HA. Fig. 1 also shows the plots of the concentration of free calcium ion versus the amounts of added NaOH obtained from the titration of the solution with

  1. Structural characterization of anion-calcium-humate complexes in phosphate-based fertilizers.

    Science.gov (United States)

    Baigorri, Roberto; Urrutia, Oscar; Erro, Javier; Mandado, Marcos; Pérez-Juste, Ignacio; Garcia-Mina, José María

    2013-07-01

    Fertilizers based on phosphate-metal-humate complexes are a new family of compounds that represents a more sustainable and bioavailable phosphorus source. The characterization of this type of complex by using solid (31)P NMR in several fertilizers, based on single superphosphate (SSP) and triple superphosphate (TSP) matrices, yielded surprising and unexpected trends in the intensity and fine structure of the (31)P NMR peaks. Computational chemistry methods allowed the characterization of phosphate-calcium-humate complexes in both SSP and TSP matrices, but also predicted the formation of a stable sulfate-calcium-humate complex in the SSP fertilizers, which has not been described previously. The stability of this complex has been confirmed by using ultrafiltration techniques. Preference towards the humic substance for the sulfate-metal phase in SSP allowed the explanation of the opposing trends that were observed in the experimental (31)P NMR spectra of SSP and TSP samples. Additionally, computational chemistry has provided an assignment of the (31)P NMR signals to different phosphate ligands as well as valuable information about the relative strength of the phosphate-calcium interactions within the crystals. PMID:23670945

  2. CALCIUM CARBONATE REDUCES IRON ABSORPTION FROM IRON SULFATE, BUT NOT WHEN IRON IS PRESENTED AS AN ORGANIC COMPLEX

    Directory of Open Access Journals (Sweden)

    E. C. CONCEI�O

    2008-09-01

    Full Text Available

    Experimental and epidemiological evidences have demonstrated that calcium inhibits iron absorption; calcium carbonate being one of the most effective calcium sources to reduce iron absorption from dietary origin or from iron sulfate. In the present work, the short-term effect of calcium from calcium carbonate on iron absorption was studied in rats, using different iron compounds (monosodium ferric EDTA, iron-bys-glicine, iron peptide complex with iron sulfate as a control. Eighty (80 animals were divided into groups of 10 animals each with homogeneous weight. After 18h fast, the animals received by gavage 5 mL of a dispersion containing one of the iron compounds (1mg Fe/kg body weight, concomitantly or not with calcium carbonate at a molar ratio of 150:1 (Ca/Fe. Two hours after the administration, the animals were sacrificed and blood was collected for serum iron determination (iron transfer rate from intestinal lumen to blood compartment. Additionally, the intestines were collected for soluble iron determination (available iron. The results demonstrated that calcium ion from calcium carbonate inhibits the iron absorption from iron sulfate, but not from organic iron (di- or trivalent complexes.

  3. Effect of magnesium and calcium complexation on the photochemical properties of norfloxacin

    International Nuclear Information System (INIS)

    The fluoroquinolone antibiotics can induce skin photosensitivity in some patients and this has been ascribed to the generation of reactive oxygen species, such as singlet oxygen (O2[1Δg]). We have studied the photochemical properties of the different ionized forms of the fluoroquinolone norfloxacin upon complexation with Mg2+ and Ca2+ ions, as it is proposed that the antibiotic exists mainly as a complex in the blood plasma. We found that the norfloxacin cation (pH 2(1Δg) generation. The norfloxacin cation does not complex Ca2+ or Mg2+ ions; when these ions are added to the solution, we observed no changes in the fluorescence quantum yields ((Φflu) and singlet oxygen yields (ΦΔ. In contrast, the neutral (6 ≤ pH ≤ 8.5) and anionic (pH > 9) forms of norfloxacin are able to complex calcium and magnesium, and their generation of O2 (1Δg) is decreased by complexation. The neutral zwitterionic form and the anionic form also quench singlet oxygen by both chemical and physical pathways regardless of complex formation, while physical quenching is observed for the cation. At pH ≥ 7.4, norfloxacin photobleaches and complexation to Ca2+ and Mg2+ increases the rate at which photobleaching occurs. Thus, both the pH of the medium and complexation with metal cations may affect the phototoxic potential of this antibiotic. (Author)

  4. Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress.

    Science.gov (United States)

    Lokdarshi, Ansul; Conner, W Craig; McClintock, Carlee; Li, Tian; Roberts, Daniel M

    2016-02-01

    During waterlogging and the associated oxygen deprivation stress, plants respond by the induction of adaptive programs, including the redirected expression of gene networks toward the synthesis of core hypoxia-response proteins. Among these core response proteins in Arabidopsis (Arabidopsis thaliana) is the calcium sensor CML38, a protein related to regulator of gene silencing calmodulin-like proteins (rgsCaMs). CML38 transcripts are up-regulated more than 300-fold in roots within 6 h of hypoxia treatment. Transfer DNA insertional mutants of CML38 show an enhanced sensitivity to hypoxia stress, with lowered survival and more severe inhibition of root and shoot growth. By using yellow fluorescent protein (YFP) translational fusions, CML38 protein was found to be localized to cytosolic granule structures similar in morphology to hypoxia-induced stress granules. Immunoprecipitation of CML38 from the roots of hypoxia-challenged transgenic plants harboring CML38pro::CML38:YFP followed by liquid chromatography-tandem mass spectrometry analysis revealed the presence of protein targets associated with messenger RNA ribonucleoprotein (mRNP) complexes including stress granules, which are known to accumulate as messenger RNA storage and triage centers during hypoxia. This finding is further supported by the colocalization of CML38 with the mRNP stress granule marker RNA Binding Protein 47 (RBP47) upon cotransfection of Nicotiana benthamiana leaves. Ruthenium Red treatment results in the loss of CML38 signal in cytosolic granules, suggesting that calcium is necessary for stress granule association. These results confirm that CML38 is a core hypoxia response calcium sensor protein and suggest that it serves as a potential calcium signaling target within stress granules and other mRNPs that accumulate during flooding stress responses. PMID:26634999

  5. Mineralization of Annexin-5-containing Lipid-Calcium-Phosphate Complexes: MODULATION BY VARYING LIPID COMPOSITION AND INCUBATION WITH CARTILAGE COLLAGENS*

    OpenAIRE

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

    2008-01-01

    Matrix vesicles (MVs) in the growth plate bind to cartilage collagens and initiate mineralization of the extracellular matrix. Native MVs have been shown to contain a nucleational core responsible for mineral formation that is comprised of Mg2+-containing amorphous calcium phosphate and lipid-calcium-phosphate complexes (CPLXs) and the lipid-dependent Ca2+-binding proteins, especially annexin-5 (Anx-5), which greatly enhances mineral formation. Incorporation of non-Ca2...

  6. Influence of Structure, Charge, and Concentration on the Pectin-Calcium-Surfactant Complexes.

    Science.gov (United States)

    Joshi, Nidhi; Rawat, Kamla; Bohidar, H B

    2016-05-12

    Polymer-surfactant complex formation of pectin with different types of surfactants, cationic (cetyltrimethylammonium bromide, CTAB and dodecyl trimethylammonium bromide, DTAB), anionic (sodium dodecyl sulfate, SDS), and neutral (Triton X-100, TX-100), was investigated at room temperature in the presence and absence of cross-linker calcium chloride using light scattering, zeta potential, rheology, and UV-vis spectroscopic measurements where the surfactant concentration was maintained below their critical micellar concentration (CMC). Results indicated that the interaction of cationic surfactant with pectin in the presence and absence of calcium chloride was much stronger compared to anionic and neutral surfactants. The neutral surfactant showed identifiable interaction despite the absence of any charged headgroup, while anionic surfactant showed feeble or very weak interaction with the polymer. The pectin-CTAB or DTAB complex formation was attributed to associative electrostatic and hydrophobic interactions. On comparison between the cationic surfactants, it was found that CTAB interacts strongly with pectin because of its long hydrocarbon chain. The morphology of complexes formed exhibited random coil structures while at higher concentration of surfactant, rod-like or extended random coil structures were noticed. Thus, functional characteristics of the complex could be tuned by varying the type of surfactant (charge and structure) and its concentration. The differential network rigidity (pectin-CTAB versus pectin-DTAB gels) obtained from rheology measurements showed that addition of a very small amount of surfactant (concentration ≪ CMC) was required for enhancing network strength, while the presence of a large amount of surfactant resulted in the formation of fragile gels. No gel formation occurred when the surfactant concentration was close to their CMC values. Considering the importance of pectin in food and pharmaceutical industry, this study is relevant

  7. Effect of magnesium and calcium complexation on the photochemical properties of norfloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Lydia; Bilski, Piotr; Chignell, C.F. [National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States)

    1996-12-01

    The fluoroquinolone antibiotics can induce skin photosensitivity in some patients and this has been ascribed to the generation of reactive oxygen species, such as singlet oxygen (O{sub 2}[{sup 1}{Delta}{sub g}]). We have studied the photochemical properties of the different ionized forms of the fluoroquinolone norfloxacin upon complexation with Mg{sup 2+} and Ca{sup 2+} ions, as it is proposed that the antibiotic exists mainly as a complex in the blood plasma. We found that the norfloxacin cation (pH < 6) shows no photodegradation after UVA irradiation and has a low quantum yield of O{sub 2}({sup 1}{Delta}{sub g}) generation. The norfloxacin cation does not complex Ca{sup 2+} or Mg{sup 2+} ions; when these ions are added to the solution, we observed no changes in the fluorescence quantum yields ({Phi}{sub flu}) and singlet oxygen yields ({Phi}{sub {Delta}}). In contrast, the neutral (6 {<=} pH {<=} 8.5) and anionic (pH > 9) forms of norfloxacin are able to complex calcium and magnesium, and their generation of O{sub 2} ({sup 1}{Delta}{sub g}) is decreased by complexation. The neutral zwitterionic form and the anionic form also quench singlet oxygen by both chemical and physical pathways regardless of complex formation, while physical quenching is observed for the cation. At pH {>=} 7.4, norfloxacin photobleaches and complexation to Ca{sup 2+} and Mg{sup 2+} increases the rate at which photobleaching occurs. Thus, both the pH of the medium and complexation with metal cations may affect the phototoxic potential of this antibiotic. (Author).

  8. Direct 3D powder printing of biphasic calcium phosphate scaffolds for substitution of complex bone defects

    International Nuclear Information System (INIS)

    The 3D printing technique based on cement powders is an excellent method for the fabrication of individual and complex bone substitutes even in the case of large defects. The outstanding bone remodeling capacity of biphasic calcium phosphates (BCPs) containing hydroxyapatite (HA) as well as tricalcium phosphate (TCP) in varying ratios makes the adaption of powder systems resulting in BCP materials to this fabrication technique a desirable aim. This study presents the synthesis and characterization of a novel powder system for the 3D printing process, intended for the production of complexly shaped BCP scaffolds by a hydraulic setting reaction of calcium carbonate and TCP with phosphoric acid. The HA/TCP ratio in the specimens could be tailored by the calcium/phosphate ratio of the starting powder. The scaffolds could be fabricated with a dimensional accuracy of >96.5% and a minimal macro pore size of 300 µm. Independent of the phase composition the printed specimens showed a microporosity of approximately 68%, while the compressive strength strongly depended on the chemical composition and increased with rising TCP content in the scaffolds to a maximum of 1.81 MPa. Post-treatment of the scaffolds with a polylactic-co-glycolic acid-solution enhanced the mechanical properties by a factor of 8. In vitro studies showed that all BCP scaffolds were cytocompatible and enhanced the cell viability as well as the cell proliferation, as compared with pure TCP. Cell proliferation is even better on BCP when compared to HA and cell viability is in a similar range on these materials. (paper)

  9. Study of the Formulation and Preparation of Chewable Tablets With a Calcium Complex Association and Vitamin D3

    Directory of Open Access Journals (Sweden)

    Emma Creţu

    2010-06-01

    Full Text Available The experimental study objective was the development of
    chewable tablets with the calcium complex association, the minerals and vitamin D3 for children, subject to the rules as stipulated by the Romanian Pharmacopoeia Xth edition. Generating sources of calcium, used as raw materials in the preparation of these tablets are natural products represented by complex mineral rich in calcium - Lactoval (R HiCal (ratio of calcium and phosphorus is 2,2:1, report the same as breast milk and 30% bovine colostrums [1, 3], making the absorption of calcium should be increased. Also, in order to
    fix and better absorb calcium in the body was added to make the preparation of these chewable tablets and vitamin D3.
    Was chosen as a method of preparing direct compression. Excipients for direct compression are diluents-binder-disaggregated. They are unitary excipients or co-processed products, multi-processed excipients together to meet those properties: microcrystalline cellulose (Vivapur 102 Ludipress, lactose (Tablettose 80, Kollidon CL Isomalt DC 100. Was also added to a lubricant (magnesium stearate and sweetener and flavoring to carry out the preparation of tablets and after 30 days as provided Romanian Pharmacopoeia Xth and its 2001 supplement, which comprises: organoleptic control, uniformity of weight, strength, disintegration and their friability. Working method chosen and make the appropriate choice leads to tablets in terms of quality standards officinal.

  10. Development of an 111In-labeled dihydropyridine complex for L-type calcium channel imaging

    International Nuclear Information System (INIS)

    [111In]-DTPA-Amlodipine complex ([111In]-DTPA-AMLO) was prepared starting high purity [111In]indium chloride and conjugated DTPA-AMLO in 30 min at room temperature in acetate buffer in high radiochemical purity (>99 %, RTLC/HPLC; specific activity: 8-10 GBq/mmol). The log P, stability, biodistribution studies and imaging studies in untreated and amlodipine-pretreated rats were determined. The tracer is mostly washed out through kidneys as expected for a dihydropyridine compound. Blocking studies demonstrated high specific binding of the tracer in calcium channel-rich organs including intestine, heart and colon. SPECT images fully supported above results in normal and treated rats. (author)

  11. Thermodynamics of the complexation of ciprofloxacin with calcium and magnesium perchlorate

    International Nuclear Information System (INIS)

    Highlights: → The thermodynamics of the reactions of ciprofloxacin (CIP) with Ca(ClO4)2 and Mg(ClO4)2 were investigated by conductometric titration. → The reactions of CIP with each ion produce two ionic complexes with the formulas M(CIP)2+ and M(CIP)22+. → The change in enthalpy and entropy were negative which indicate that the complexation is driven by the enthalpy change. - Abstract: The thermodynamics of the reactions of ciprofloxacin (CIP) with calcium perchlorate (Ca(ClO4)2) and magnesium perchlorate (Mg(ClO4)2) have been investigated in water-methanol solvent using conductometric titration. The reactions of CIP with each ion produce two ionic complexes with the general formulas M(CIP)2+ and M(CIP)22+. The stability constants K1 and K2 at 25 oC for the complexes formed from the reaction with Ca(ClO4)2 were 8.84 x 104 and 3.62 x 104, respectively. For the reaction with Mg(ClO4)2K1 and K2 were 1.72 x 105 and 2.50 x 103, respectively. The enthalpy (ΔH1, ΔH2, ΔH12) and entropy (ΔS1, ΔS2, ΔS12) of complexation reactions were determined from the temperature dependence of the complexation constants. The reactions of CIP with both ions are accompanied by a decrease in entropy (ΔS12 = -468.12 and -478.89 J/K mol for complexation with Ca(ClO4)2 and Mg(ClO4)2, respectively) and enthalpy (ΔH12 = -193.09 and -192.01 kJ/mol for complexation with Ca(ClO4)2 and Mg(ClO4)2, respectively), which indicate that the reactions are driven by the enthalpy change.

  12. Thermodynamics of the complexation of ciprofloxacin with calcium and magnesium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Al-Mustafa, Jamil, E-mail: malkawi@just.edu.jo [Department of Applied Chemistry, Faculty of Arts and Sciences, Jordan University of Science and Technology, P.O. Box 3030, Irbid (Jordan); Taha, Ziyad A. [Department of Applied Chemistry, Faculty of Arts and Sciences, Jordan University of Science and Technology, P.O. Box 3030, Irbid (Jordan)

    2011-07-10

    Highlights: {yields} The thermodynamics of the reactions of ciprofloxacin (CIP) with Ca(ClO{sub 4}){sub 2} and Mg(ClO{sub 4}){sub 2} were investigated by conductometric titration. {yields} The reactions of CIP with each ion produce two ionic complexes with the formulas M(CIP){sup 2+} and M(CIP){sub 2}{sup 2+}. {yields} The change in enthalpy and entropy were negative which indicate that the complexation is driven by the enthalpy change. - Abstract: The thermodynamics of the reactions of ciprofloxacin (CIP) with calcium perchlorate (Ca(ClO{sub 4}){sub 2}) and magnesium perchlorate (Mg(ClO{sub 4}){sub 2}) have been investigated in water-methanol solvent using conductometric titration. The reactions of CIP with each ion produce two ionic complexes with the general formulas M(CIP){sup 2+} and M(CIP){sub 2}{sup 2+}. The stability constants K{sub 1} and K{sub 2} at 25 {sup o}C for the complexes formed from the reaction with Ca(ClO{sub 4}){sub 2} were 8.84 x 10{sup 4} and 3.62 x 10{sup 4}, respectively. For the reaction with Mg(ClO{sub 4}){sub 2}K{sub 1} and K{sub 2} were 1.72 x 10{sup 5} and 2.50 x 10{sup 3}, respectively. The enthalpy ({Delta}H{sub 1}, {Delta}H{sub 2}, {Delta}H{sub 12}) and entropy ({Delta}S{sub 1}, {Delta}S{sub 2}, {Delta}S{sub 12}) of complexation reactions were determined from the temperature dependence of the complexation constants. The reactions of CIP with both ions are accompanied by a decrease in entropy ({Delta}S{sub 12} = -468.12 and -478.89 J/K mol for complexation with Ca(ClO{sub 4}){sub 2} and Mg(ClO{sub 4}){sub 2}, respectively) and enthalpy ({Delta}H{sub 12} = -193.09 and -192.01 kJ/mol for complexation with Ca(ClO{sub 4}){sub 2} and Mg(ClO{sub 4}){sub 2}, respectively), which indicate that the reactions are driven by the enthalpy change.

  13. Calcium sulfoaluminate cement blended with OPC: A potential binder to encapsulate low-level radioactive slurries of complex chemistry

    International Nuclear Information System (INIS)

    Investigations were carried out in order to solidify in cement a low-level radioactive waste of complex chemistry obtained by mixing two process streams, a slurry produced by ultra-filtration and an evaporator concentrate with a salinity of 600 gxL-1. Direct cementation with Portland cement (OPC) was not possible due to a very long setting time of cement resulting from borates and phosphates contained in the waste. According to a classical approach, this difficulty could be solved by pre-treating the waste to reduce adverse cement-waste interactions. A two-stage process was defined, including precipitation of phosphates and sulfates at 60 deg. C by adding calcium and barium hydroxide to the waste stream, and encapsulation with a blend of OPC and calcium aluminate cement (CAC) to convert borates into calcium quadriboroaluminate. The material obtained with a 30% waste loading complied with specifications. However, the pre-treatment step made the process complex and costly. A new alternative was then developed: the direct encapsulation of the waste with a blend of OPC and calcium sulfoaluminate cement (CSA) at room temperature. Setting inhibition was suppressed, which probably resulted from the fact that, when hydrating, CSA cement formed significant amounts of ettringite and calcium monosulfoaluminate hydrate which incorporated borates into their structure. As a consequence, the waste loading could be increased to 56% while keeping acceptable properties at the laboratory scale.

  14. Use of multiple singular value decompositions to analyze complex intracellular calcium ion signals

    KAUST Repository

    Martinez, Josue G.

    2009-12-01

    We compare calcium ion signaling (Ca(2+)) between two exposures; the data are present as movies, or, more prosaically, time series of images. This paper describes novel uses of singular value decompositions (SVD) and weighted versions of them (WSVD) to extract the signals from such movies, in a way that is semi-automatic and tuned closely to the actual data and their many complexities. These complexities include the following. First, the images themselves are of no interest: all interest focuses on the behavior of individual cells across time, and thus, the cells need to be segmented in an automated manner. Second, the cells themselves have 100+ pixels, so that they form 100+ curves measured over time, so that data compression is required to extract the features of these curves. Third, some of the pixels in some of the cells are subject to image saturation due to bit depth limits, and this saturation needs to be accounted for if one is to normalize the images in a reasonably un-biased manner. Finally, the Ca(2+) signals have oscillations or waves that vary with time and these signals need to be extracted. Thus, our aim is to show how to use multiple weighted and standard singular value decompositions to detect, extract and clarify the Ca(2+) signals. Our signal extraction methods then lead to simple although finely focused statistical methods to compare Ca(2+) signals across experimental conditions.

  15. Application of calcium peroxide activated with Fe(II)-EDDS complex in trichloroethylene degradation.

    Science.gov (United States)

    Zhang, Xiang; Gu, Xiaogang; Lu, Shuguang; Miao, Zhouwei; Xu, Minhui; Fu, Xiaori; Qiu, Zhaofu; Sui, Qian

    2016-10-01

    This study was conducted to assess the application of calcium peroxide (CP) activated with Fe(II) chelated by (S,S)-ethylenediamine-N,N'-disuccinic acid (EDDS) to enhance trichloroethylene (TCE) degradation in aqueous solution. It was indicated that EDDS prevented soluble iron from precipitation, and the optimum molar ratio of Fe(II)/EDDS to accelerate TCE degradation was 1/1. The influences of initial TCE, CP and Fe(II)-EDDS concentration were also investigated. The combination of CP and Fe(II)-EDDS complex rendered the efficient degradation of TCE at near neutral pH range. Chemical probe and scavenger tests identified that TCE degradation mainly owed to the oxidation of HO while O2(-) promoted HO generation. Cl(-), HCO3(-) and humic acid were found to inhibit CP/Fe(II)-EDDS performance on different levels. In conclusion, the application of CP activated with Fe(II)-EDDS complex is a promising technology in chemical remediation of groundwater, while further research in practical implementation is needed. PMID:27351899

  16. Proteomic Analysis of Calcium- and Phosphorylation-dependentCalmodulin Complexes in Mammalian Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Deok-Jin; Wang, Daojing

    2006-05-26

    Protein conformational changes due to cofactor binding (e.g. metal ions, heme) and/or posttranslational modifications (e.g. phosphorylation) modulate dynamic protein complexes. Calmodulin (CaM) plays an essential role in regulating calcium (Ca{sup 2+}) signaling and homeostasis. No systematic approach on the identification of phosphorylation-dependent Ca{sup 2+}/CaM binding proteins has been published. Herein, we report a proteome-wide study of phosphorylation-dependent CaM binding proteins from mammalian cells. This method, termed 'Dynamic Phosphoprotein Complex Trapping', 'DPPC Trapping' for short, utilizes a combination of in vivo and in vitro assays. The basic strategy is to drastically shift the equilibrium towards endogenous phosphorylation of Ser, Thr, and Tyr at the global scale by inhibiting corresponding phosphatases in vivo. The phosphorylation-dependent calmodulin-binding proteins are then trapped in vitro in a Ca{sup 2+}-dependent manner by CaM-Sepharose chromatography. Finally, the isolated calmodulin-binding proteins are separated by SDS-PAGE and identified by LC/MS/MS. In parallel, the phosphorylation-dependent binding is visualized by silver staining and/or Western blotting. Using this method, we selectively identified over 120 CaM-associated proteins including many previously uncharacterized. We verified ubiquitin-protein ligase EDD1, inositol 1, 4, 5-triphosphate receptor type 1 (IP{sub 3}R1), and ATP-dependent RNA helicase DEAD box protein 3 (DDX3), as phosphorylation-dependent CaM binding proteins. To demonstrate the utilities of our method in understanding biological pathways, we showed that pSer/Thr of IP{sub 3}R1 in vivo by staurosporine-sensitive kinase(s), but not by PKA/PKG/PKC, significantly reduced the affinity of its Ca{sup 2+}-dependent CaM binding. However, pSer/Thr of IP{sub 3}R1 did not substantially affect its Ca{sup 2+}-independent CaM binding. We further showed that phosphatase PP1, but not PP2A or PP2B

  17. In vivo biocompatibility of new nano-calcium-deficient hydroxyapatite/poly-amino acid complex biomaterials

    Directory of Open Access Journals (Sweden)

    Dai ZY

    2015-10-01

    Full Text Available Zhenyu Dai,1,2,* Yue Li,3,* Weizhong Lu,2,* Dianming Jiang,4 Hong Li,1 Yonggang Yan,1 Guoyu Lv,1 Aiping Yang1 1College of Physical Science and Technology, Sichuan University, Chengdu, 2Department of Orthopedics, Chongqing Hospital of Traditional Chinese Medicine, 3Department of Clinical Laboratory, the Second Affiliated Hospital, 4Department of Orthopedics, the First Affiliated Hospital, Chongqing Medical University, Chongqing, People’s Republic of China *These authors contributed equally to this work Objective: To evaluate the compatibility of novel nano-calcium-deficient hydroxyapatite/poly-amino acid (n-CDHA/PAA complex biomaterials with muscle and bone tissue in an in vivo model.Methods: Thirty-two New Zealand white rabbits were used in this study. Biomaterials were surgically implanted into each rabbit in the back erector spinae and in tibia with induced defect. Polyethylene was implanted into rabbits in the control group and n-CDHA/PAA into those of the experimental group. Animals were examined at four different points in time: 2 weeks, 4 weeks, 12 weeks, and 24 weeks after surgery. They were euthanized after embolization. Back erector spinae muscles with the surgical implants were examined after hematoxylin and eosin (HE staining at these points in time. Tibia bones with the surgical implants were examined by X-ray and scanning electron microscopy (SEM at these points in time to evaluate the interface of the bone with the implanted biomaterials. Bone tissues were sectioned and subjected to HE, Masson, and toluidine blue staining.Results: HE staining of back erector spinae muscles at 4 weeks, 12 weeks, and 24 weeks after implantation of either n-CDHA/PAA or polyethylene showed disappearance of inflammation and normal arrangement in the peripheral tissue of implant biomaterials; no abnormal staining was observed. At 2 weeks after implantation, X-ray imaging of bone tissue samples in both experimental and control groups showed that

  18. Structural insights into calcium-bound S100P and the V domain of the RAGE complex.

    Directory of Open Access Journals (Sweden)

    Srinivasa R Penumutchu

    Full Text Available The S100P protein is a member of the S100 family of calcium-binding proteins and possesses both intracellular and extracellular functions. Extracellular S100P binds to the cell surface receptor for advanced glycation end products (RAGE and activates its downstream signaling cascade to meditate tumor growth, drug resistance and metastasis. Preventing the formation of this S100P-RAGE complex is an effective strategy to treat various disease conditions. Despite its importance, the detailed structural characterization of the S100P-RAGE complex has not yet been reported. In this study, we report that S100P preferentially binds to the V domain of RAGE. Furthermore, we characterized the interactions between the RAGE V domain and Ca(2+-bound S100P using various biophysical techniques, including isothermal titration calorimetry (ITC, fluorescence spectroscopy, multidimensional NMR spectroscopy, functional assays and site-directed mutagenesis. The entropy-driven binding between the V domain of RAGE and Ca(+2-bound S100P was found to lie in the micromolar range (Kd of ∼ 6 µM. NMR data-driven HADDOCK modeling revealed the putative sites that interact to yield a proposed heterotetrameric model of the S100P-RAGE V domain complex. Our study on the spatial structural information of the proposed protein-protein complex has pharmaceutical relevance and will significantly contribute toward drug development for the prevention of RAGE-related multifarious diseases.

  19. Crystallization and preliminary crystallographic analysis of calcium-binding protein-2 from Entamoeba histolytica and its complexes with strontium and the IQ1 motif of myosin V

    International Nuclear Information System (INIS)

    Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. Calcium plays a pivotal role in the pathogenesis of amoebiasis, a major disease caused by Entamoeba histolytica. Two domains with four canonical EF-hand-containing calcium-binding proteins (CaBPs) have been identified from E. histolytica. Even though they have very high sequence similarity, these bind to different target proteins in a Ca2+-dependent manner, leading to different functional pathways. Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. The crystals belong to space group P21, with unit-cell parameters a = 111.74, b = 68.83, c = 113.25 Å, β = 116.7°. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. The crystals belong to space group P21, with unit-cell parameters a = 69.18, b = 112.03, c = 93.42 Å, β = 92.8°. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. This complex was crystallized with MPD and ethanol as precipitating agents. These crystals belong to space group P21, with unit-cell parameters a = 60.5, b = 69.86, c = 86.5 Å, β = 97.9°

  20. Crystallization and preliminary crystallographic analysis of calcium-binding protein-2 from Entamoeba histolytica and its complexes with strontium and the IQ1 motif of myosin V

    Energy Technology Data Exchange (ETDEWEB)

    Gourinath, S., E-mail: sgourinath@mail.jnu.ac.in; Padhan, Narendra; Alam, Neelima; Bhattacharya, Alok [School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2005-04-01

    Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. Calcium plays a pivotal role in the pathogenesis of amoebiasis, a major disease caused by Entamoeba histolytica. Two domains with four canonical EF-hand-containing calcium-binding proteins (CaBPs) have been identified from E. histolytica. Even though they have very high sequence similarity, these bind to different target proteins in a Ca{sup 2+}-dependent manner, leading to different functional pathways. Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 111.74, b = 68.83, c = 113.25 Å, β = 116.7°. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 69.18, b = 112.03, c = 93.42 Å, β = 92.8°. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. This complex was crystallized with MPD and ethanol as precipitating agents. These crystals belong to space group P2{sub 1}, with unit-cell parameters a = 60.5, b = 69.86, c = 86.5 Å, β = 97.9°.

  1. CALCIUM CARBONATE REDUCES IRON ABSORPTION FROM IRON SULFATE, BUT NOT WHEN IRON IS PRESENTED AS AN ORGANIC COMPLEX

    OpenAIRE

    E. C. CONCEI�O; Machado, A.A.; C. IZUMI; O. Freitas

    2008-01-01

    Experimental and epidemiological evidences have demonstrated that calcium inhibits iron absorption; calcium carbonate being one of the most effective calcium sources to reduce iron absorption from dietary origin or from iron sulfate. In the present work, the short-term effect of calcium from calcium carbonate on iron absorption was studied in rats, using different ir...

  2. Calcium-dependent and calcium-independent signals in the conglutinin-binding assay (KgBa) for immune complexes. Influence of anti-collagen-antibodies

    DEFF Research Database (Denmark)

    Holmskov, U; Haas, Henning de; Teisner, B;

    1992-01-01

    of IgG to solid phase bovine conglutinin was also observed to a variable degree in normal and pathological sera. However, in this situation the IgG binding was largely calcium-independent, was not inhibited by GlcNAc and did not decrease after prolonged incubation of the serum at 37 degrees C. The...

  3. Formation and stability of calcium complexes of dimethyl sulfoxide in water

    Czech Academy of Sciences Publication Activity Database

    Jakl, M.; Straka, Michal; Jaklová Dytrtová, Jana; Roithová, J.

    2014-01-01

    Roč. 360, č. 1 (2014), s. 8-14. ISSN 1387-3806 R&D Projects: GA ČR GP13-21409P Grant ostatní: GA ČR(CZ) GAP206/12/0539 Institutional support: RVO:61388963 Keywords : bonding energies * DFT * ESI-MS * complexation * speciation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.972, year: 2014

  4. Effect of casein phosphopeptide-amorphous calcium phosphate on the flexural strength of enamel-dentin complex following extracoronal bleaching

    Directory of Open Access Journals (Sweden)

    Diatri Nari Ratih

    2015-03-01

    Full Text Available Background: Bleaching can affect the mechanical properties of enamel-dentin complex, such as flexural strength. Casein phosphopeptide-amorphus calcium phosphate (CPP-ACP is often used following bleaching treatment to reduce hypersensitivity and to increase demineralization of tooth. Purpose: The purpose of the study was to investigate the effect of CPP-ACP on the flexural strength of enamel-dentin complex following extracoronal bleaching. Methods: Forty-eight enamel-dentin plates (size 8 x 2 x 3 mm were randomly assigned into 6 groups, each consisted of 8 samples. Group 1, no bleaching and immersed in artificial saliva. Group 2, no bleaching, CPP-ACP application only. Group 3, bleaching using 15% carbamide peroxide. Group 4, similar to group 3, except application of CPP-ACP for the times between bleaching. Group 5, bleaching with 40% hydrogen peroxide. Group 6, similar to group 5, except application of CPP-ACP for the times between bleaching. Flexural strength of each enamel-dentin plate was tested by threepoint bending test using universal testing machine. Results: The results showed that 15% carbamide peroxide and 40% hydrogen peroxide significantly reduced flexural strength of enamel-dentin (216.25±26.44 MPa and 206.67±32.07 MPa respectively. Conversely, application of CPP-ACP following both bleachings increased flexural strength (266.75± 28.27MPa and 254.58±36.59 MPa respectively. A two-way Anova revealed that extracoronal bleaching agents significantly reduced flexural strength (p<0.05. Conclusion: Extracoronal bleaching agents reduce flexural strength, whereas application of CPP-ACP following bleaching either with 15% carbamide peroxide or 40% hydrogen peroxide can increase the flexural strength of enamel-dentin complex.

  5. Neuronal calcium sparks and intracellular calcium “noise”

    OpenAIRE

    Melamed-Book, Naomi; Kachalsky, Sylvia G.; Kaiserman, Igor; Rahamimoff, Rami

    1999-01-01

    Intracellular calcium ions are involved in many forms of cellular function. To accommodate so many control functions, a complex spatiotemporal organization of calcium signaling has developed. In both excitable and nonexcitable cells, calcium signaling was found to fluctuate. Sudden localized increases in the intracellular calcium concentration—or calcium sparks—were found in heart, striated and smooth muscle, Xenopus Laevis oocytes, and HeLa and P12 cells. In the nervous system, intracellular...

  6. Structures and spectroscopic characterization of calcium chloride-nicotinamide, -isonicotinamide, -picolinamide and praseodymium bromide-nicotinamide complexes.

    Science.gov (United States)

    Xue, Junhui; Jiang, Ye; Li, Weihong; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Zhang, Gaohui; Bu, Xiaoxia; Liu, Kexin; Chen, Jia'er; Wu, Jinguang

    2015-02-25

    The coordination structures formed by calcium complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) and praseodymium bromide-na are reported. The structures of CaCl2·(C6H6N2O)2·2H2O (Ca-na), CaCl2·(C6H6N2O)2·4H2O (Ca-ina), CaCl2·(C6H6N2O)2·5H2O (Ca-pa) and PrBr3·(C6H6N2O)2·6H2O (PrBr-na) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Raman spectroscopies. Carbonyl oxygen of nicotinamide is coordinated to Ca(2+), but it is O-monodentate (carbonyl oxygen) and N,O-bidentate ligand (pyridyl nitrogen and carbonyl oxygen) for Pr(3+) to form a chain structure in PrBr-na. For isonicotinamide, only carbonyl oxygen atom is coordinated to Ca(2+). Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Ca(2+) to form a five-membered ring structure. The crystal structure and spectroscopic results indicate the differences of the coordination of Ca and Pr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation. Unlike transition metal ions, Sr(2+) or lanthanide ions, Ca(2+) is inclined to coordinate to carbonyl oxygen atoms of the ligands. PMID:25280333

  7. Effect of fluoridated casein phospopeptide-amorphous-calcium phosphate complex, chlorhexidine fluoride mouthwash on shear bond strength of orthodontic brackets: A comparative in vitro study

    OpenAIRE

    C A Abdul Shahariyar; Anurag D Mahale; Kishore Kumar; Rohan Rai

    2016-01-01

    Objective: The aim of the current study was to determine the effects of casein phosphopeptide amorphous calcium-phosphate (CPP-ACP) complex, chlorhexidine fluoride mouthwash on shear bond strengths (SBSs) of orthodontic brackets. Materials and Methods: About sixty extracted healthy human premolar teeth with intact buccal enamel were divided into two equal groups to which brackets were bonded using self-etching primers (SEPs) and conventional means respectively. These were further equally divi...

  8. Structures of CaV2 Ca2+/CaM-IQ Domain Complexes Reveal Binding Modes That Underlie Calcium-Dependent Inactivation And Facilitation

    International Nuclear Information System (INIS)

    Calcium influx drives two opposing voltage-activated calcium channel (CaV) self-modulatory processes: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF). Specific Ca2+/calmodulin (Ca2+/CaM) lobes produce CDI and CDF through interactions with the CaVα1 subunit IQ domain. Curiously, Ca2+/CaM lobe modulation polarity appears inverted between CaV1s and CaV2s. Here, we present crystal structures of CaV2.1, CaV2.2, and CaV2.3 Ca2+/CaM-IQ domain complexes. All display binding orientations opposite to CaV1.2 with a physical reversal of the CaM lobe positions relative to the IQ α-helix. Titration calorimetry reveals lobe competition for a high-affinity site common to CaV1 and CaV2 IQ domains that is occupied by the CDI lobe in the structures. Electrophysiological experiments demonstrate that the N-terminal CaV2 Ca2+/C-lobe anchors affect CDF. Together, the data unveil the remarkable structural plasticity at the heart of CaV feedback modulation and indicate that CaV1 and CaV2 IQ domains bear a dedicated CDF site that exchanges Ca2+/CaM lobe occupants

  9. Calcium - urine

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003603.htm Calcium - urine To use the sharing features on this ... enable JavaScript. This test measures the amount of calcium in urine. All cells need calcium in order ...

  10. 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 ...

  11. CALCIUM-INDUCED SUPRAMOLECULAR STRUCTURES IN THE CALCIUM CASEINATE SYSTEM

    Science.gov (United States)

    The molecular details deciphering the spontaneous calcium-induced protein aggregation process in the calcium caseinate system remain obscure. Understanding this complex process could lead to potential new applications of this important food ingredient. In this work, we studied calcium-induced supra...

  12. N-type calcium channel/syntaxin/SNAP-25 complex probed by antibodies to II-III intracellular loop of the α1B subunit

    International Nuclear Information System (INIS)

    Neuronal voltage-dependent calcium channels are integral components of cellular excitation and neurosecretion. In addition to mediating the entry of calcium across the plasma membrane, both N-type and P/Q-type voltage-dependent calcium channels have been shown to form stable complexes with synaptic vesicle and presynaptic membrane proteins, indicating a structural role for the voltage-dependent calcium channels in secretion. Recently, detailed structural analyses of N-type calcium channels have identified residues amino acids 718-963 as the site in the rat α1B subunit that mediates binding to syntaxin, synaptosome-associated protein of 25andpuncsp; omitted000 mol. wt and synaptotagmin [Sheng et al. (1996) Nature 379, 451-454]. The purpose of this study was to employ site-directed antibodies to target domains within and outside of the interaction site on the rat α1B to probe potential binding sites for syntaxin/SNAP-25/synaptotagmin.Our results demonstrate that both antibodies employed in this study have access to their epitopes on the α1B as evidenced by equivalent immunoprecipitation of native [125I]omega-conotoxin GVIA-labeled α1B protein from CHAPS-solubilized preparations. The N-type voltage-dependent calcium channel immunoprecipitated by Ab CW14, the antibody directed to a domain outside of the synprint site, is associated with syntaxin and SNAP-25 with the recovery of these proteins, increasing in parallel to the recovery of α1B. However, when we used the antibody raised to an epitope within the synprint site (Ab CW8) to immunoprecipitate N-type calcium channels, the α1B was depleted of more than 65% of syntaxin and 80% of SNAP-25 when compared to the recovery of these proteins using Ab CW14. This is the first report of a defined epitope on the α1B subunit II-III loop (amino acids 863-875) whose perturbation by a site-directed antibody influences the dissociation of SNAP-25 and syntaxin. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights

  13. Structures of Ca(V) Ca**2+/CaM-IQ Domain Complexes Reveal Binding Modes That Underlie Calcium-Dependent Inactivation And Facilitation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, E.Y.; Rumpf, C.H.; Fujiwara, Y.; Cooley, E.S.; Petegem, F.Van; Minor, D.L., Jr.

    2009-05-20

    Calcium influx drives two opposing voltage-activated calcium channel (Ca{sub V}) self-modulatory processes: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF). Specific Ca{sup 2+}/calmodulin (Ca{sup 2+}/CaM) lobes produce CDI and CDF through interactions with the Ca{sub V}{alpha}{sub 1} subunit IQ domain. Curiously, Ca{sup 2+}/CaM lobe modulation polarity appears inverted between Ca{sub V}1s and Ca{sub V}2s. Here, we present crystal structures of Ca{sub V}2.1, Ca{sub V}2.2, and Ca{sub V}2.3 Ca{sup 2+}/CaM-IQ domain complexes. All display binding orientations opposite to Ca{sub V}1.2 with a physical reversal of the CaM lobe positions relative to the IQ {alpha}-helix. Titration calorimetry reveals lobe competition for a high-affinity site common to Ca{sub V}1 and Ca{sub V}2 IQ domains that is occupied by the CDI lobe in the structures. Electrophysiological experiments demonstrate that the N-terminal Ca{sub V}2 Ca{sup 2+}/C-lobe anchors affect CDF. Together, the data unveil the remarkable structural plasticity at the heart of Ca{sub V} feedback modulation and indicate that Ca{sub V}1 and Ca{sub V}2 IQ domains bear a dedicated CDF site that exchanges Ca{sup 2+}/CaM lobe occupants.

  14. Impact of uranyl-calcium-carbonato complexes on uranium(VI) adsorption to synthetic and natural sediments.

    Science.gov (United States)

    Stewart, Brandy D; Mayes, Melanie A; Fendorf, Scott

    2010-02-01

    Adsorption on soil and sediment solids may decrease aqueous uranium concentrations and limit its propensity for migration in natural and contaminated settings. Uranium adsorption will be controlled in large part by its aqueous speciation, with a particular dependence on the presence of dissolved calcium and carbonate. Here we quantify the impact of uranyl speciation on adsorption to both goethite and sediments from the Hanford Clastic Dike and Oak Ridge Melton Branch Ridgetop formations. Hanford sediments were preconditioned with sodium acetate and acetic acid to remove carbonate grains, and Ca and carbonate were reintroduced at defined levels to provide a range of aqueous uranyl species. U(VI) adsorption is directly linked to UO(2)(2+) speciation, with the extent of retention decreasing with formation of ternary uranyl-calcium-carbonato species. Adsorption isotherms under the conditions studied are linear, and K(d) values decrease from 48 to 17 L kg(-1) for goethite, from 64 to 29 L kg (-1) for Hanford sediments, and from 95 to 51 L kg(-1) for Melton Branch sediments as the Ca concentration increases from 0 to 1 mM at pH 7. Our observations reveal that, in carbonate-bearing waters, neutral to slightly acidic pH values ( approximately 5) and limited dissolved calcium are optimal for uranium adsorption. PMID:20058915

  15. 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...

  16. Macrophage activation by a vanadyl-aspirin complex is dependent on L-type calcium channel and the generation of nitric oxide

    International Nuclear Information System (INIS)

    Bone homeostasis is the result of a tight balance between bone resorption and bone formation where macrophage activation is believed to contribute to bone resorption. We have previously shown that a vanadyl(IV)-aspirin complex (VOAspi) regulates cell proliferation and differentiation of osteoblasts in culture. In this study, we assessed VOAspi and VO effects and their possible mechanism of action on a mouse macrophage cell line RAW 264.7. Both vanadium compounds inhibited cell proliferation in a dose-dependent manner. Nifedipine completely reversed the VOAspi-induced macrophage cytotoxicity, while it could not block the effect of VO. VOAspi also stimulated nitric oxide (NO) production, the oxidation of dihydrorhodamine 123 (DHR-123) and enhanced the expression of both constitutive and inducible isoforms of nitric oxide syntases (NOS). All these effects were abolished by nifedipine. Althogether our finding give evidence that VOAspi-induced macrophage cytotoxicity is dependent on L-type calcium channel and the generation of NO though the induction of eNOS and iNOS. Contrary, the parent compound VO exerted a cytotoxic effect by mechanisms independent of a calcium entry and the NO/NOS activation

  17. Preparation and preliminary biological evaluation of radiogallium-labeled DTPA-amlodipine complex for possible L-type calcium channel imaging

    Energy Technology Data Exchange (ETDEWEB)

    Firuzyar, Tahereh; Shafiee-Ardestani, Mehdi; Khalaj, Ali [Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of). Faculty of Pharmacy; Jalilian, Amir R.; Fazaeli, Yousef; Aboudzadeh, Mohammad Reza [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of). Radiopharmacy Research Group

    2014-07-01

    A DTPA-conjugated amlodipine analog (DTPA-AMLO) 3, was prepared for possible voltage gated calcium channel imaging after radiolabeling with Ga-67. [{sup 67}Ga]-DTPA-AMLO complex was prepared starting [{sup 67}Ga]gallium chloride and DTPA-AMLO in 60-90 min at 50-60 C in phosphate buffer. The partition co-efficient and stability of the tracer was determined in final solution (25 C) and presence of human serum (37 C) up to 24 h. The biodistribution of the labeled compound in wild-type rats were determined up to 72 h using organ counting and SPECT. The radiolabled complex was prepared in high radiochemical purity (>96%, RTLC and >98% HPLC) and significant specific activity (7-10 GBq/mmol). The log P for the complex was calculated as -0.594, consistent with a water soluble complex. The tracer is mostly washed out through kidneys which were in full compliance with the amlodipine metabolism and imaging studies demonstrated the same behavior. The tracer uptake in organs with smooth muscles was observed in stomach, colon as well as intestine.

  18. Preparation and preliminary biological evaluation of radiogallium-labeled DTPA-amlodipine complex for possible L-type calcium channel imaging

    International Nuclear Information System (INIS)

    A DTPA-conjugated amlodipine analog (DTPA-AMLO) 3, was prepared for possible voltage gated calcium channel imaging after radiolabeling with Ga-67. [67Ga]-DTPA-AMLO complex was prepared starting [67Ga]gallium chloride and DTPA-AMLO in 60-90 min at 50-60 C in phosphate buffer. The partition co-efficient and stability of the tracer was determined in final solution (25 C) and presence of human serum (37 C) up to 24 h. The biodistribution of the labeled compound in wild-type rats were determined up to 72 h using organ counting and SPECT. The radiolabled complex was prepared in high radiochemical purity (>96%, RTLC and >98% HPLC) and significant specific activity (7-10 GBq/mmol). The log P for the complex was calculated as -0.594, consistent with a water soluble complex. The tracer is mostly washed out through kidneys which were in full compliance with the amlodipine metabolism and imaging studies demonstrated the same behavior. The tracer uptake in organs with smooth muscles was observed in stomach, colon as well as intestine.

  19. Effect of fluoridated casein phospopeptide-amorphous-calcium phosphate complex, chlorhexidine fluoride mouthwash on shear bond strength of orthodontic brackets: A comparative in vitro study

    Directory of Open Access Journals (Sweden)

    C A Abdul Shahariyar

    2016-01-01

    Full Text Available Objective: The aim of the current study was to determine the effects of casein phosphopeptide amorphous calcium-phosphate (CPP-ACP complex, chlorhexidine fluoride mouthwash on shear bond strengths (SBSs of orthodontic brackets. Materials and Methods: About sixty extracted healthy human premolar teeth with intact buccal enamel were divided into two equal groups to which brackets were bonded using self-etching primers (SEPs and conventional means respectively. These were further equally divided into three subgroups - (1 control (2 CPP-ACP (3 chlorhexidine fluoride mouthwash. The SBSs were then measured using a universal testing machine. Results: SBS of the conventional group was significantly higher than the self-etching group. The intragroup differences were statistically insignificant. Conclusion: CPP-ACP, chlorhexidine fluoride mouthwash did not adversely affect SBS of orthodontic brackets irrespective of the method of conditioning. Brackets bonded with conventional technique showed greater bond strengths as compared to those bonded with SEP.

  20. Alkaline earth organometallic compounds in homogeneous catalysis : Synthesis, characterization and catalytic activity of calcium and magnesium complexes

    NARCIS (Netherlands)

    Penafiel, Johanne

    2016-01-01

    Homogeneous catalysis has been developed mainly through the use of transition metal complexes. However, transition-metal catalysts, often highly toxic, are becoming increasingly rare and consequently more expensive. Therefore, the search for sustainable alternatives is nowadays of great importance.

  1. Energy transfer in solution-based complexes of CdTe nanocrystals electrostatically bound by calcium ions

    International Nuclear Information System (INIS)

    Colloidal semiconductor nanocrystals with controllable surface properties are attractive objects for use as building blocks in different functional structures within the bottom-up assembly approach. We produced stable complexes from differently-sized water soluble CdTe nanocrystals capped by mercaptoacid stabilizers through electrostatic interactions of negatively charged carboxylic groups of capping ligands with positively charged Ca(II) cations. Energy transfer between smaller nanocrystals (donors) and larger nanocrystals (acceptors) in fabricated complexes is demonstrated by means of steady-state and time-resolved photoluminescence spectroscopy, paving the way to nanocrystal-based light harvesting structures

  2. The Structure of Chondroitin B Lyase Complexed with Glycosaminoglycan Oligosaccharides Unravels a Calcium-dependent Catalytic Machinery*

    OpenAIRE

    Michel, Gurvan; Pojasek, Kevin; Li, Yunge; Sulea, Traian; Linhardt, Robert J.; Raman, Rahul; Prabhakar, Vikas; Sasisekharan, Ram; Cygler, Miroslaw

    2004-01-01

    Chondroitinase B from Pedobacter heparinus is the only known enzyme strictly specific for dermatan sulfate and is a widely used enzymatic tool for the structural characterization of glycosaminoglycans. This β-helical polysaccharide lyase belongs to family PL-6 and cleaves the β(1,4) linkage of dermatan sulfate in a random manner, yielding 4,5-unsaturated dermatan sulfate disaccharides as the product. The previously reported structure of its complex with a dermatan sulfate disaccharide product...

  3. Transport of Calcium Ions into Mitochondria.

    Science.gov (United States)

    Xu, Zhaolong; Zhang, Dayong; He, Xiaolan; Huang, Yihong; Shao, Hongbo

    2016-06-01

    To uptake calcium ions of mitochondria is of significant functional connotation for cells, because calcium ions in mitochondria are involved in energy production, regulatory signals transfer, and mitochondrial permeability transition pore opening and even programmed cell death of apoptosis, further playing more roles in plant productivity and quality. Cytoplasmic calcium ions access into outer mitochondrial membrane (OMM) from voltage dependent anion-selective channel (VDAC) and were absorbed into inner mitochondrial membrane (IMM) by mitochondrial calcium uniporter (MCU), rapid mitochondrial calcium uptake (RaM) or mitochondrial ryanodine receptor (mRyR). Although both mitochondria and the mechanisms of calcium transport have been extensively studied, but there are still long-standing or even new challenges. Here we review the history and recent discoveries of the mitochondria calcium ions channel complex involved calcium assimilation, and discuss the role of calcium ions into mitochondria. PMID:27252588

  4. Calcium Carbonate

    Science.gov (United States)

    ... before being swallowed; do not swallow them whole. Drink a full glass of water after taking either the regular or chewable tablets or capsules. Some liquid forms of calcium carbonate must be shaken well before use.Do not ...

  5. 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<0.0001) or...

  6. Calcium Calculator

    Science.gov (United States)

    ... Latvia - Lebanon - Libya - Lithuania - Luxembourg - Macedonia, Republic of - Malaysia - Malta - Mexico - Moldova - Morocco - Netherlands - New Zealand - Nigeria - ... and Statistics Popular content Calcium content of common foods What is Osteoporosis? The Board Introduction to Bone ...

  7. Cytosolic calcium concentration is reduced by photolysis of a nitrosyl ruthenium complex in vascular smooth muscle cells.

    Science.gov (United States)

    Lunardi, C N; Cacciari, A L; Silva, R S; Bendhack, L M

    2006-11-01

    The effect of the NO donors cis-[RuCl(bpy)(2)(NO)](PF(6)) (RUNOCL) and sodium nitroprusside (SNP) on the cytosolic Ca(2+) concentration ([Ca(2+)](c)) was studied in cells isolated from the rat aorta smooth muscle of cells isolated from the rat aorta smooth muscle. SNP is a metal nitrosyl complex made up of iron, cyanide groups, and a nitro moiety; the RUNOCL complex is made up of ruthenium and bipyridine ligands, with chloride and nitrosyl groups in the ruthenium axial positions. Rat aorta smooth muscle cells were loaded with fluo-3 acetoxymethyl ester (Fluo-3 AM) and imaged by a confocal scanning laser microscope excited with the 488 nm line of the argon ion laser. Fluorescence emission was measured at 510 nm. One of the NO donors, RUNOCL (100 micromol/L) or SNP (100 micromol/L), was then added to the cell chamber and the fluorescent intensity percentage (%IF) was measured after 240 s. RUNOCL reduced the %IF to 60.0+/-10.0% of the initial value. After treatment with the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ) (10 micromol/L), the measurement of %IF was 81.0+/-5.0% (n=4). In the presence of tetraethylammonium (TEA) (1 mmol/L) the %IF was 79.0+/-6.4% (n=4). A combination of ODQ and TEA increased the %IF to 97.0+/-3.5% (n=4). As for SNP, it reduced the %IF to 81.4+/-4.7% (n=4), but this effect was inhibited by ODQ (%IF 94.0+/-3.6%; n=4) and TEA (%IF 88.0+/-2.1%; n=4). The combination of ODQ and TEA increased (%IF 92.0+/-2.8%; n=4). Taken together, these results indicate that both the new NO donor RUNOCL and SNP reduce [Ca(2+)](c). Our data also give evidence that soluble guanylyl cyclase and K(+) channels sensitive to TEA are involved in the mechanisms responsible for the reduction in [Ca(2+)](c) of the rat aorta smooth muscle cells. PMID:16564714

  8. On the importance of satellite lines to the He-like alpha complex and the G ration for calcium, iron, and nickel

    Energy Technology Data Exchange (ETDEWEB)

    Oelgoetz, Justin R [Los Alamos National Laboratory; Fontes, Christopher J [Los Alamos National Laboratory; Zhang, Hong L [Los Alamos National Laboratory; Nahar, Sultana N [OHIO STATE UNIV; Pradhan, Anil K [OHIO STATE UNIV

    2008-01-01

    New, more detailed calculations of the emission spectra of the He-like Ko complex of calcium, iron and nickel have been carried out using data from both distorted-wave and R-matrix calculations. The value of the GD ratio (a corrected version of the G ratio that accounts for the effect of unresolved satellite lines) is significantly enhanced at temperatures below the temperature of He-like maximum abundance. Furthermore it is shown that satellite lines are important contributors to the G D ratio at temperatures well above the temperature of maximum abundance. These new calculations demonstrate that satellite lines need to be included in models of He-like Ko spectra even at relatively high temperatures. The excellent agreement between spectra and line ratios calculated from R-matrix and distorted-wave data also confirms the validity of models based on distorted-wave data for highly charged systems, provided the effect of resonances are taken into account as independent processes.

  9. Calcium pyrophosphate arthritis

    Science.gov (United States)

    Calcium pyrophosphate dihydrate deposition disease; CPPD disease; Acute CPPD arthritis; Pseudogout ... Calcium pyrophosphate arthritis is caused by the collection of salt called calcium pyrophosphate dihydrate (CPPD). The buildup ...

  10. Calcium and bones

    Science.gov (United States)

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  11. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of calcium ...

  12. 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 ...

  13. Some aspects of the aqueous solution chemistry of the Na+/Ca2+/OH-/Cit3- system: The structure of a new calcium citrate complex forming under hyperalkaline conditions

    Science.gov (United States)

    Gácsi, Attila; Kutus, Bence; Buckó, Ákos; Csendes, Zita; Peintler, Gábor; Pálinkó, István; Sipos, Pál

    2016-08-01

    In the present study, we show that in hyperalkaline (pH > 13) aqueous solutions, Ca2+ forms a new, so far unknown complex species with the citrate ion, the structure of which is different from the well-known CaCit-(aq) species present in solutions of close to neutral pH. The solubility of Ca3Cit2(s) was found to increase significantly under hyperalkaline conditions. The decrease in the electric conductivity and the variations observed in the freezing point depression of such solutions also indicate complexation. From 1H NMR measurements, in this complex, the citrate ion is suggested to be in quadruply deprotonated form. From the variation of the 2JHH geminal proton coupling constant, two neighboring carboxylate groups are coordinated to the calcium ion in a monodentate mode (besides the alcoholate). The optimal structure of the complex with the composition of CaCitH-12-(aq) has also been calculated using DFT calculations, applying the Polarizable Continuum Model. Sodium ion-pairing was found to compete efficiently with this calcium complexation process, and in solutions with high Na-ion content, the equilibria are shifted towards the formation of NaCit2-(aq) and Na2Cit-(aq) ion pairs.

  14. Influence of calcium oxalate crystal accumulation on the calcium content of seeds from Medicago truncatula.

    Science.gov (United States)

    Nakata, Paul A

    2012-04-01

    Crystals of calcium oxalate often form in cells adjacent to the vascular bundles in the tissues along the xylem stream. This spatial crystal pattern suggests a role for calcium oxalate formation in regulating calcium transport and partitioning to edible organs such as seeds. To investigate this potential role, microscopic and biochemical comparisons were conducted on the different tissues of Medicago truncatula wild-type and the calcium oxalate defective (cod) 5 which lacks the ability to accumulate prismatic crystals in the cells adjacent to the vascular bundles. Calcium measurements showed that cod5 seeds had more calcium and cod5 pods contained less calcium than the corresponding wild-type tissues. Roots, stems, and leaves from cod5 and wild-type had similar calcium content. Although cod5 was devoid of prismatic crystals, cod5 pods were observed to form druse crystals of calcium oxalate not found in wild-type pods. Taken together these findings suggest a functional role for calcium oxalate formation in regulating calcium transport to the seeds. Regulating calcium uptake at the roots also appeared to be another point of control in determining seed calcium content. Overall, regulating the long distance transport and partitioning of calcium to the seeds appears to be a complex process with multiple points of control. PMID:22325887

  15. 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, exhausti

  16. 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. PMID:19400592

  17. Calcium-sensitive immunoaffinity chromatography

    DEFF Research Database (Denmark)

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

    2014-01-01

    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......Ab. This antibody was characterized by binding to CL-LK at hypo- and physiological calcium concentrations and dissociated from CK-LK at hyperphysiological concentrations of calcium. We purified CL-LK from plasma to a purity of 41% and a yield of 38%, resulting in a purification factor of more than 88......,000 in a single step. To evaluate the efficiency of this new purification scheme, we purified CL-LK using the same calcium-sensitive mAb in combination with acidic elution buffer and by using calcium-dependent anti-CL-K1 mAbs in combination with EDTA elution buffer. We found that calcium...

  18. Stochastic Kinetics of Intracellular Calcium Oscillations

    Institute of Scientific and Technical Information of China (English)

    陈昌胜; 曾仁端

    2003-01-01

    A stochastic model of intracellular calcium oscillations is put forward by taking into account the random opening-closing of Ca2+ channels in endoplasmic reticulum (ER) membrane. The numerical results of the stochastic model show simple and complex calcium oscillations, which accord with the experiment results.

  19. 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 ...

  20. Coronary Calcium Scan

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  1. 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 ...

  2. 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 ...

  3. Calcium in diet

    Science.gov (United States)

    Diet - calcium ... Calcium is one of the most important minerals for the human body. It helps form and maintain healthy teeth and bones. A proper level of calcium in the body over a lifetime can help ...

  4. 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 ...

  5. 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...

  6. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

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

    2010-01-01

    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...... affected burst firing in mossy fibres; this paired-pulse depression was reduced by GABA B antagonists. While our results indicated that a presynaptic rosette electrophysiologically functioned as a unit, topical GABA application showed that calcium signals in the branches of complex rosettes could be...

  7. How calcium makes endocytic receptors attractive

    DEFF Research Database (Denmark)

    Andersen, Christian B F; Moestrup, Søren K

    2014-01-01

    receptor. Endosomal acidification and calcium efflux lead to the essential ligand-receptor affinity switch and separation. Recent data, including crystal structures of receptor-ligand complexes, now reveal how calcium, in different types of domain scaffolds, functions in a common way as a removable...... '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 the...... receptor calcium sites....

  8. The role of calcium in human aging.

    Science.gov (United States)

    Beto, Judith A

    2015-01-01

    Calcium is an essential nutrient that is necessary for many functions in human health. Calcium is the most abundant mineral in the body with 99% found in teeth and bone. Only 1% is found in serum. The serum calcium level is tightly monitored to remain within normal range by a complex metabolic process. Calcium metabolism involves other nutrients including protein, vitamin D, and phosphorus. Bone formation and maintenance is a lifelong process. Early attention to strong bones in childhood and adulthood will provide more stable bone mass during the aging years. Research has shown that adequate calcium intake can reduce the risk of fractures, osteoporosis, and diabetes in some populations. The dietary requirements of calcium and other collaborative nutrients vary slightly around the world. Lactose intolerance due to lactase deficiency is a common cause of low calcium intake. Strategies will be discussed for addressing this potential barrier to adequate intake. The purpose of this narrative review is a) to examine the role of calcium in human health, b) to compare nutrient requirements for calcium across lifecycle groups and global populations, c) to review relationships between calcium intake, chronic disease risk, and fractures, and d) to discuss strategies to address diet deficiencies and lactose intolerance. PMID:25713787

  9. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  10. Role of mitochondria and network connectivity in intercellular calcium oscillations

    CERN Document Server

    Dokukina, I V; Grachev, E A; Gunton, J D; Dokukina, Irina V.; Gracheva, Maria E.; Grachev, Eugene A.; Gunton, James D.

    2005-01-01

    Mitochondria are large-scale regulators of cytosolic calcium under normal cellular conditions. In this paper we model the complex behavior of mitochondrial calcium during the action of inositol 1,4,5-trisphosphate on a single cell and find results that are in good agreement with recent experimental studies. We also study the influence of the cellular network connectivity on intercellular signalling via gap junction diffusion. We include in our model the dependence of the junctional conductivity on the cytosolic calcium concentrations in adjacent cells. We consider three different mechanisms of calcium wave propagation through gap junctions: via calcium diffusion, inositol 1,4,5-trisphosphate diffusion, and both calcium and inositol 1,4,5-trisphosphate diffusion. We show that inositol 1,4,5-trisphosphate diffusion is the mechanism of calcium wave propagation and that calcium diffusion is the mechanism of synchronization of cytosolic calcium oscillations in adjacent cells. We also study the role of different to...

  11. Calcium and Vitamin D

    Science.gov (United States)

    ... Home › Patients › Treatment › Calcium/Vitamin D Calcium/Vitamin D Getting enough calcium and vitamin D is essential ... counter medications and calcium supplements. What is Vitamin D and What Does it Do? Vitamin D plays ...

  12. Importance of Calcium

    OpenAIRE

    TANDOĞAN, Berivan; ULUSU, N. Nuray

    2005-01-01

    Calcium is the most abundant mineral in the body. Calcium regulates many cellular processes and has important structural roles in living organisms. Skeletal muscle structure and function, polymerisation of fibrin and the conduction of impulses in the nervous system are regulated by calcium. Calcium is an important intracellular messenger in protozoa, plants, and animals. Calcium-transporting systems which are located in the plasma membrane and in the organelles, regulate the ionic concentrati...

  13. Comparison of tomographic coronary artery calcification index (calcium score) and ultrasonographic measurement of intima-media complex thickness in diabetic subjects

    International Nuclear Information System (INIS)

    At present, there is a number of diagnostic imaging procedures allowing for the evaluation of atherosclerosis. The earliest, subclinical stage of atherosclerosis can be visualized with the development of computed tomography (CT) and ultrasound (US) techniques. Therefore, the purpose of this study was to assess the degree of coronary artery calcification and carotid intima-media thickness in diabetic subjects divided into different age groups. Fifty-six men, aged from 18 to 72 were included in the study. Participants were divided into 4 groups according to age (18–30, 31–45, 46–60 and more than 60 years). Two tests were performed: coronary calcium score (CS) determination and intima-media thickness (IMT) in ultrasound. CS was performed using a multi-slice scanner. Images were analyzed using the Agatson method. Ultrasound examinations were performed using a 9–12-MHz linear transducer. The correlation coefficient between calcium score index (CSI) and age of patients was 0.52 (p<0.001). The correlation between duration of diabetes and CSI was significantly lower (r=0.3; p<0.05). The increase of IMT is associated with age to a much greater extent and the correlation coefficient was 0.63 (p<0.001). IMT depended on the duration of diabetes, but the correlation was also weak (r=0.35; p<0.01). Comparison of the findings obtained in the presented study and in the group of healthy subjects proves that influence of diabetes on vascular deterioration may be observed, even among young individuals. Obtained results allow to make the following conclusions: 1. Calcium score index remains low in the group of male patients with diabetes before the age of 45. 2. Intima-media thickness correlates well with age (r=0.6; p<0.05) and weaker with the duration of diabetes (r=0.35; p<0.05). 3. IMT assessment may be a useful tool to identify the increased predisposition to atherosclerosis, also before the age of 30

  14. Production of precipitated calcium carbonate from calcium silicates and carbon dioxide

    International Nuclear Information System (INIS)

    The possibilities for reducing carbon dioxide emissions from the pulp and paper industry by calcium carbonation are presented. The current precipitated calcium carbonate (PCC) production uses mined, crushed calcium carbonate as raw materials. If calcium silicates were used instead, carbon dioxide emissions from the calcination of carbonates would be eliminated. In Finland, there could, thus, be a potential for eliminating 200 kt of carbon dioxide emissions per year, considering only the PCC used in the pulp and paper industry. A preliminary investigation of the feasibility to produce PCC from calcium silicates and the potential to replace calcium carbonate as the raw material was made. Calcium carbonate can be manufactured from calcium silicates by various methods, but only a few have been experimentally verified. The possibility and feasibility of these methods as a replacement for the current PCC production process was studied by thermodynamic equilibrium calculations using HSC software and process modelling using Aspen Plus[reg]. The results from the process modelling showed that a process that uses acetic acid for extraction of the calcium ions is a high potential option for sequestering carbon dioxide by mineral carbonation. The main obstacle seems to be the limited availability and relatively high price of wollastonite, which is a mineral with high calcium silicate content. An alternative is to use the more common, but also more complex, basalt rock instead

  15. Characterization of dihydropyridine-sensitive calcium channels

    International Nuclear Information System (INIS)

    The structural and regulatory properties of the dihydropyridine-sensitive calcium channel were studied by isolating protein components of the channel complex from both cardiac and skeletal muscle. Hydrodynamic characterization of the (+)-(3H)PN200-110-labeled cardiac calcium channel revealed that the protein components of the complex had a total molecular mass of 370,000 daltons, a Stokes radius of 86 angstrom, and a frictional ratio of 1.3. A technique is described for the rapid incorporation of the CHAPS solubilized skeletal muscle calcium channel complex into phospholipid vesicles. 45Ca2+ uptake into phospholipid vesicles containing calcium channels was inhibited by phenylalkalamine calcium antagonists. Wheat germ lectin followed by DEAE chromatography of the CHAPS solubilized complex resulted in the dissociation of regulatory components of the complex from channel components. The DEAE preparation gave rise to 45Ca2+ uptake that was not inhibited by verapamil but was inhibited by GTPgS activated G0. The inhibition of 45Ca2+ uptake by verapamil was restored by co-reconstitution of wash fractions from wheat germ lectin chromatography. Phosphorylation of polypeptides in this fraction by polypeptide-dependent protein kinase prevented the restoration of verapamil sensitivity. The partial purification of an endogenous skeletal muscle ADP-ribosyltransferase is also described. ADP-ribosylation of the α2 subunit of the calcium channel complex is enhanced by polylysine and inhibited by GTPγS, suggesting that regulation of this enzyme is under the control of GTP binding proteins. These results suggest a complex model, involving a number of different protein components, for calcium channel regulation in skeletal muscle

  16. Calcium in diet

    Science.gov (United States)

    ... best source. Milk and dairy products such as yogurt, cheeses, and buttermilk contain a form of calcium ... the amount of calcium in a dairy product. Yogurt, most cheeses, and buttermilk are excellent sources of ...

  17. Fenoprofen calcium overdose

    Science.gov (United States)

    Fenoprofen calcium is a type of medicine called a nonsteroidal anti-inflammatory drug. It is a prescription pain medicine used to relieve symptoms of arthritis . Fenoprofen calcium overdose occurs when someone takes more than the ...

  18. Calcium channel blocker overdose

    Science.gov (United States)

    ... this 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 ...

  19. 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 ...

  20. Calcium and magnesium disorders.

    Science.gov (United States)

    Goff, Jesse P

    2014-07-01

    Hypocalcemia is a clinical disorder that can be life threatening to the cow (milk fever) and predisposes the animal to various other metabolic and infectious disorders. Calcium homeostasis is mediated primarily by parathyroid hormone, which stimulates bone calcium resorption and renal calcium reabsorption. Parathyroid hormone stimulates the production of 1,25-dihydroxyvitamin D to enhance diet calcium absorption. High dietary cation-anion difference interferes with tissue sensitivity to parathyroid hormone. Hypomagnesemia reduces tissue response to parathyroid hormone. PMID:24980727

  1. 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.

  2. 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 cardiop

  3. 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.

  4. Uses of 1H NMR and 13C NMR spectroscopy in studies of phenylenedioxydiacetamides complexation with the cations of calcium and potassium in solution

    International Nuclear Information System (INIS)

    The complexation abilities and the coordination sites of 12 derivatives using infrared, 1HNMR and 13C NMR spectroscopy are analyzed. The spectroscopic results indicate that only the 1,2-phenylenedioxydiacetamides are suitable ligands; the 1,3 derivatives did not react. These ionophors 1-8 represent fourdentale chelating ligands where all four oxygen atmos are involved in bonds to the metal. Independent from its charge one cations is coordinate by two ionophors. (M.J.C.)

  5. Intakes of vegetables and related nutrients such as vitamin B complex, potassium, and calcium, are negatively correlated with risk of stroke in Korea

    OpenAIRE

    Park, Yongsoon

    2010-01-01

    Consumption of vegetables and fruits is associated with a reduced risk of stroke, but it is unclear whether their protective effects are due to antioxidant vitamins or folate and metabolically related B vitamins. The purpose of the study was to test the hypothesis that intake of fruits and vegetables, which are major sources of antioxidant and vitamin B complex vitamins, reduces the risk of stroke. Cases consisted of patients diagnosed with first event of stroke (n = 69). Controls (n = 69) we...

  6. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  7. EXERCISE ENHANCING CALCIUM ABSORPTION MECHANISM

    OpenAIRE

    Muliani

    2013-01-01

    Calcium has important role in many biological processes therefore calcium homeostasis should be maintained. Imbalance in calcium homeostasis would affects the bone metabolism, neuromuscular function, blood coagulation, cell proliferation and signal transduction. Homeostasis of calcium is maintained by three major organs: gastrointestinal tract, bone and kidney. Intestinal calcium absorption is the sole mechanism to supply calcium to the body. Calcium absorption controlled by calcitropic hormo...

  8. Calcium-insensitive splice variants of mammalian E1 subunit of 2-oxoglutarate dehydrogenase complex with tissue-specific patterns of expression.

    Science.gov (United States)

    Denton, Richard M; Pullen, Timothy J; Armstrong, Craig T; Heesom, Kate J; Rutter, Guy A

    2016-05-01

    The 2-oxoglutarate dehydrogenase (OGDH) complex is an important control point in vertebrate mitochondrial oxidative metabolism, including in the citrate cycle and catabolism of alternative fuels including glutamine. It is subject to allosteric regulation by NADH and the ATP/ADP ratio, and by Ca(2+) through binding to the E1 subunit. The latter involves a unique Ca(2+)-binding site which includes D(114)ADLD (site 1). Here, we describe three splice variants of E1 in which either the exon expressing this site is replaced with another exon (loss of site 1, LS1) or an additional exon is expressed leading to the insertion of 15 amino acids just downstream of site 1 (Insert), or both changes occur together (LS1/Insert). We show that all three variants are essentially Ca(2+)-insensitive. Comparison of massive parallel sequence (RNA-Seq) databases demonstrates predominant expression of the Ca(2+)-sensitive archetype form in heart and skeletal muscle, but substantial expression of the Ca(2+)-insensitive variants in brain, pancreatic islets and other tissues. Detailed proteomic and activity studies comparing OGDH complexes from rat heart and brain confirmed the substantial difference in expression between these tissues. The evolution of OGDH variants was explored using bioinformatics, and this indicated that Ca(2+)-sensitivity arose with the emergence of chordates. In all species examined, this was associated with the co-emergence of Ca(2+)-insensitive variants suggesting a retained requirement for the latter in some settings. Tissue-specific expression of OGDH splice variants may thus provide a mechanism that tunes the control of the enzyme to the specialized metabolic and signalling needs of individual cell types. PMID:26936970

  9. Dengue and Calcium

    OpenAIRE

    Shivanthan, Mitrakrishnan C; Rajapakse, Senaka

    2014-01-01

    Dengue is potentially fatal unless managed appropriately. No specific treatment is available and the mainstay of treatment is fluid management with careful monitoring, organ support, and correction of metabolic derangement. Evidence with regards to the role of calcium homeostasis in dengue is limited. Low blood calcium levels have been demonstrated in dengue infection and hypocalcemia maybe more pronounced in more severe forms. The cause of hypocalcemia is likely to be multifactorial. Calcium...

  10. Measurements of intracellular calcium

    International Nuclear Information System (INIS)

    Intracellular calcium concentration ([Ca2+]i) has been measured in cultured cells by using Fura-2 load cells and a computer-controlled Perkin Elmer LS-5B spectrofluorometer. Increased [Ca2+]i in cells exposed to extracellular bilirubin was observed both with and without extracellular calcium. However, the increase was considerable larger with extracellular calcium. The enhancement of [Ca2+]i became smaller with decreasing bilirubin/BSA (bovine serum albumine) ratio. 5 refs., 5 figs

  11. Calcium controls the assembly of the photosynthetic water-oxidizing complex: a cadmium(II) inorganic mutant of the Mn4Ca core.

    Science.gov (United States)

    Bartlett, John E; Baranov, Sergei V; Ananyev, Gennady M; Dismukes, G Charles

    2008-03-27

    Perturbation of the catalytic inorganic core (Mn4Ca1OxCly) of the photosystem II-water-oxidizing complex (PSII-WOC) isolated from spinach is examined by substitution of Ca2+ with cadmium(II) during core assembly. Cd2+ inhibits the yield of reconstitution of O2-evolution activity, called photoactivation, starting from the free inorganic cofactors and the cofactor-depleted apo-WOC-PSII complex. Ca2+ affinity increases following photooxidation of the first Mn2+ to Mn3+ bound to the 'high-affinity' site. Ca2+ binding occurs in the dark and is the slowest overall step of photoactivation (IM1-->IM1* step). Cd2+ competitively blocks the binding of Ca2+ to its functional site with 10- to 30-fold higher affinity, but does not influence the binding of Mn2+ to its high-affinity site. By contrast, even 10-fold higher concentrations of Cd2+ have no effect on O2-evolution activity in intact PSII-WOC. Paradoxically, Cd2+ both inhibits photoactivation yield, while accelerating the rate of photoassembly of active centres 10-fold relative to Ca2+. Cd2+ increases the kinetic stability of the photooxidized Mn3+ assembly intermediate(s) by twofold (mean lifetime for dark decay). The rate data provide evidence that Cd2+ binding following photooxidation of the first Mn3+, IM1-->IM1*, causes three outcomes: (i) a longer intermediate lifetime that slows IM1 decay to IM0 by charge recombination, (ii) 10-fold higher probability of attaining the degrees of freedom (either or both cofactor and protein d.f.) needed to bind and photooxidize the remaining 3 Mn2+ that form the functional cluster, and (iii) increased lability of Cd2+ following Mn4 cluster assembly results in (re)exchange of Cd2+ by Ca2+ which restores active O2-evolving centres. Prior EPR spectroscopic data provide evidence for an oxo-bridged assembly intermediate, Mn3+(mu-O2(-))Ca2+, for IM1*. We postulate an analogous inhibited intermediate with Cd2+ replacing Ca2+. PMID:17954439

  12. Effects of serum immunoglobulins from patients with complex regional pain syndrome (CRPS) on depolarisation-induced calcium transients in isolated dorsal root ganglion (DRG) neurons.

    Science.gov (United States)

    Reilly, Joanne M; Dharmalingam, Backialakshmi; Marsh, Stephen J; Thompson, Victoria; Goebel, Andreas; Brown, David A

    2016-03-01

    Complex regional pain syndrome (CRPS) is thought to have an auto-immune component. One such target recently proposed from the effects of auto-immune IgGs on Ca(2+) transients in cardiac myocytes and cell lines is the α1-adrenoceptor. We have tested whether such IgGs exerted comparable effects on nociceptive sensory neurons isolated from rat dorsal root ganglia. Depolarisation-induced [Ca(2+)]i transients were generated by applying 30mM KCl for 2min and monitored by Fura-2 fluorescence imaging. No IgGs tested (including 3 from CRPS patients) had any significant effect on these [Ca(2+)]i transients. However, IgG from one CRPS patient consistently and significantly reduced the K(+)-induced response of cells that had been pre-incubated for 24h with a mixture of inflammatory mediators (1μM histamine, 5-hydroxytryptamine, bradykinin and PGE2). Since this pre-incubation also appeared to induce a comparable inhibitory response to the α1-agonist phenylephrine, this is compatible with the α1-adrenoceptor as a target for CRPS auto-immunity. A mechanism whereby this might enhance pain is suggested. PMID:26708558

  13. Serum Calcium Level in Hypertension

    OpenAIRE

    Hazari, Mohammed Abdul Hannan; Arifuddin, Mehnaaz Sameera; Muzzakar, Syed; Reddy, Vontela Devender

    2012-01-01

    Background: The alterations in extracellular calcium level may influence intracellular calcium level and possibly play a role in the pathogenesis of essential hypertension. Aim: The purpose was to find out the association between serum calcium levels and hypertension; and to compare the serum calcium levels between normotensive controls, hypertensive subjects on calcium channel blockers, and hypertensive subjects on antihypertensive medication other than calcium channel blockers. Materials an...

  14. Calcium bioaccessibility and uptake by human intestinal like cells following in vitro digestion of casein phosphopeptide-calcium aggregates.

    Science.gov (United States)

    Perego, Silvia; Del Favero, Elena; De Luca, Paola; Dal Piaz, Fabrizio; Fiorilli, Amelia; Cantu', Laura; Ferraretto, Anita

    2015-06-01

    Casein phosphopeptides (CPPs), derived by casein proteolysis, can bind calcium ions and keep them in solution. In vitro studies have demonstrated CPP-induced cell calcium uptake, depending on the formation of (CPP + calcium) complexes and on the degree of differentiation of the intestinal cells. With the present study, we address the persistence of the complexes and of the CPP-induced calcium uptake in intestinal like cells after the digestion process, thus examining their eligibility to serve as nutraceuticals. A calcium-preloaded CPP preparation of commercial origin (Ca-CPPs) was subjected to in vitro digestion. The evolution of the supramolecular structure of the Ca-CPP complexes was studied using laser-light and X-ray scattering. The bioactivity of the pre- and post-digestion Ca-CPPs was determined in differentiated Caco2 and HT-29 cells by video imaging experiments using Fura-2. We found that Ca-CPP aggregates keep a complex supramolecular organization upon digestion, despite getting smaller in size and increasing internal calcium dispersion. Concomitantly and most interestingly, digested Ca-CPPs clearly enhance the uptake of calcium ions, especially in Caco2 cells. In contrast, digestion depletes the ability of post-loaded decalcified-CPPs (Ca-dekCPPs), with a weaker internal structure, to induce calcium uptake. The enhanced bioactivity reached upon digestion strongly suggests a recognized role of Ca-CPPs, in the form used here, as nutraceuticals. PMID:25927875

  15. Calcium Imaging Perspectives in Plants

    Directory of Open Access Journals (Sweden)

    Chidananda Nagamangala Kanchiswamy

    2014-03-01

    Full Text Available The calcium ion (Ca2+ is a versatile intracellular messenger. It provides dynamic regulation of a vast array of gene transcriptions, protein kinases, transcription factors and other complex downstream signaling cascades. For the past six decades, intracellular Ca2+ concentration has been significantly studied and still many studies are under way. Our understanding of Ca2+ signaling and the corresponding physiological phenomenon is growing exponentially. Here we focus on the improvements made in the development of probes used for Ca2+ imaging and expanding the application of Ca2+ imaging in plant science research.

  16. 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 calciu

  17. Calcium and iron absorption: mechanism of action and nutritional importance.

    Science.gov (United States)

    Hallberg, L; Rossander-Hultén, L; Brune, M; Gleerup, A

    1992-05-01

    We investigated the inhibitory effect of calcium on iron absorption in 57 human subjects. Three studies suggested that the effect is not located in the gastrointestinal tract. The presence of phytate in a meal and formation of calcium-iron-phytate complexes is not a prerequisite for the inhibition. The relative increase in iron absorption by ascorbic acid was the same in meals with and without calcium, suggesting that calcium did not influence the balance between enhancing and inhibiting ligands in the gastrointestinal lumen. No inhibiting effect on iron absorption was seen when adding 3 mg calcium to 0.01 mg iron (molar ratio Ca/Fe = 420). Previous studies showing a marked inhibition by calcium had a lower molar ratio, but greater amounts of calcium were given. This suggests that a minimal concentration of calcium is needed to achieve an effect. The present results indirectly support our original hypothesis that the inhibitory effect of calcium on iron absorption is situated within the intestinal mucosal cells. The practical nutritional implications of the inhibitory effect of calcium are considerable since addition of milk, milkshake or cheese to common meals such as pizza or hamburger meals reduced iron absorption by 50-60%. It is recommended to reduce the intake of dairy products with the main meals providing most of the dietary iron, especially for those having the highest iron requirements i.e. children, teenagers and women at childbearing age. PMID:1600930

  18. 21 CFR 184.1212 - Calcium pantothenate.

    Science.gov (United States)

    2010-04-01

    ... the B complex. Only the D-isomer of pantothenic acid has vitamin activity, although both the D-isomer...-propionaldehyde and pantolactone. (b) Calcium pantothenate meets the specifications of the Food Chemicals Codex..._regulations/ibr_locations.html. (c) In accordance with § 184.1(b)(1), the ingredient is used in food with...

  19. Determination of calcium and magnesium in nuclear grade alumina by ion chromatography technique

    International Nuclear Information System (INIS)

    A simple method for solubilization of alumina and separation of magnesium and calcium from alumina matrix was developed by initial coprecipitation of those elements with iron(III) hydroxide. Calcium and magnesium were later separated from iron chloride anionic complex in a Dowex 1-X 10 anionic exchange resin. The ion chromatography tecnnique was employed for the analysis of calcium and magnesium. One hundred percent recovery for calcium and magnesium was obtained in their separation from alumina. A precision of 6% and 10% for magnesium and calcium, respectively, was obtained in alumina samples analysis which contain less than 0,02% of magnesium and less than 0,08% of calcium. (Author)

  20. 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...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...... calcium binds silicon primarily as calcium silicates and less as potassium calcium silicates....

  1. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  2. [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 ab

  3. Antagonist effects of calcium on borosilicate glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Depierre, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Angeli, F., E-mail: frederic.angeli@cea.fr [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Frizon, F. [CEA Marcoule, DTCD SECM LP2C, 30207 Bagnols sur Cèze (France); Gin, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage.

  4. 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

  5. Calcium Binding to Amino Acids and Small Glycine Peptides in Aqueous Solution: Toward Peptide Design for Better Calcium Bioavailability.

    Science.gov (United States)

    Tang, Ning; Skibsted, Leif H

    2016-06-01

    Deprotonation of amino acids as occurs during transfer from stomach to intestines during food digestion was found by comparison of complex formation constants as determined electrochemically for increasing pH to increase calcium binding (i) by a factor of around 6 for the neutral amino acids, (ii) by a factor of around 4 for anions of the acidic amino acids aspartic and glutamic acid, and (iii) by a factor of around 5.5 for basic amino acids. Optimized structures of the 1:1 complexes and ΔHbinding for calcium binding as calculated by density functional theory (DFT) confirmed in all complexes a stronger calcium binding and shorter calcium-oxygen bond length in the deprotonated form. In addition, the stronger calcium binding was also accompanied by a binding site shift from carboxylate binding to chelation by α-amino group and carboxylate oxygen for leucine, aspartate, glutamate, alanine, and asparagine. For binary amino acid mixtures, the calcium-binding constant was close to the predicted geometric mean of the individual amino acid binding constants indicating separate binding of calcium to two amino acids when present together in solution. At high pH, corresponding to conditions for calcium absorption, the binding affinity increased in the order Lys < Arg < Cys < Gln < Gly ∼ Ala < Asn < His < Leu < Glu< Asp. In a series of glycine peptides, calcium-binding affinity was found to increase in the order Gly-Leu ∼ Gly-Gly < Ala-Gly < Gly-His ∼ Gly-Lys-Gly < Glu-Cys-Gly < Gly-Glu, an ordering confirmed by DFT calculations for the dipeptides and which also accounted for large synergistic effects in calcium binding for up to 6 kJ/mol when compared to the corresponding amino acid mixtures. PMID:27159329

  6. The Effect of Calcium on the Binding of Calmodulin to Calcium/Calmodulin Protein Kinase II.

    Science.gov (United States)

    Porta, Angela R.

    2000-01-01

    Introduces a follow-up laboratory experiment demonstrating the formation change when calcium binds to calmodulin. This conformation change allows this complex to bind to a target protein. Presents the necessary information to conduct the experiment and discusses the results. (YDS)

  7. Identification of CP12 as a Novel Calcium-Binding Protein in Chloroplasts

    Directory of Open Access Journals (Sweden)

    Agostinho Gomes Rocha

    2013-08-01

    Full Text Available Calcium plays an important role in the regulation of several chloroplast processes. However, very little is still understood about the calcium fluxes or calcium-binding proteins present in plastids. Indeed, classical EF-hand containing calcium-binding proteins appears to be mostly absent from plastids. In the present study we analyzed the stroma fraction of Arabidopsis chloroplasts for the presence of novel calcium-binding proteins using 2D-PAGE separation followed by calcium overlay assay. A small acidic protein was identified by mass spectrometry analyses as the chloroplast protein CP12 and the ability of CP12 to bind calcium was confirmed with recombinant proteins. CP12 plays an important role in the regulation of the Calvin-Benson-Bassham Cycle participating in the assembly of a supramolecular complex between phosphoribulokinase and glyceraldehyde 3-phosphate dehydrogenase, indicating that calcium signaling could play a role in regulating carbon fixation.

  8. 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)

  9. CALCIUM SOAP LUBRICANTS

    OpenAIRE

    Alaz, Izer; Tugce, Nefise; Devrim, Balköse

    2014-01-01

    The article studies the properties of calcium stearate (CaSt2) and lubricants produced on its basis. These lubricants were prepared using sodium stearate and calcium chloride by subsidence from aqueous solutions. The CaSt2 and the light fraction of crude oil were mixed together to obtain lubricating substances. The article shows that CaSt2 had the melting temperature of 142.8 C that is higher than the melting temperature of crude oil (128 C). The compositions of obtained lubricants were stu...

  10. A sensor for calcium uptake

    OpenAIRE

    Collins, Sean; Meyer, Tobias

    2010-01-01

    Mitochondria — the cell’s power plants — increase their energy production in response to calcium signals in the cytoplasm. A regulator of the elusive mitochondrial calcium channel has now been identified.

  11. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Trials Resources and Publications Children's Bone Health and Calcium: Condition Information Skip sharing on social media links ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  12. Calcium: a code coupling tool

    International Nuclear Information System (INIS)

    Today, the calculation performances of computers allow the precise and global simulation of complex industrial processes such as the functioning of a nuclear reactor core. One can question the need for the elaboration of new global numerical models in order to make use of the overall capability of computers. Another less time consuming solution consist in the coupling of existing well validated numerical models in order to make them working together. This paper presents the basic principles of the coupling of numerical codes, the tools required, the Calcium tool for codes coupling and an example of application of this tool in the coupling of the THYC (EdF), COCCINELLE (EdF) and CATHARE (CEA-EdF-Framatome) codes for the modeling of the thermal-hydraulic and neutronic behaviour of a reactor core during accidental situation. (J.S.)

  13. Characterization of ionomycin as a calcium ionophore.

    Science.gov (United States)

    Liu, C; Hermann, T E

    1978-09-10

    The ionophorous properties of a new antibiotic, ionomycin, have been studied. It was found that the antibiotic is capable of extracting calcium ion from the bulk of an aqueous phase into an organic phase. The antibiotic also acts as a mobile ion carrier to transport the cation across a solvent barrier. The divalent cation selectivity order for ionomycin as determined by ion competition experiments was found to be: Ca greater than Mg greater than Sr = Ba, where the binding of strontium and barium by the antibiotic is insignificant. The antibiotic also binds La3+ to some extent, but its complexation with monovalent alkali metal ions is negligible. Measurement of the binding of ionomycin with Ca2+ indicates that ionomycin complexes and transports calcium ion in a one to one stoichiometry. PMID:28319

  14. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  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...

  16. Preparation of Hollow Calcium Silicate Microparticles by Simple Emulsion

    OpenAIRE

    Eiichi Toorisaka; Syotaro Nagamatsu; Yasunobu Saruwatari; Makoto Hirata; Tadashi Hano

    2014-01-01

    Hollow calcium silicate microparticles were prepared by mixing a water-in-oil (W/O) emulsion containing silicate ions in aqueous phase with an oil phase containing a calcium/di-2-ethylhexyl phosphoric acid (D2EHPA) complex. The inorganic precipitation reaction at the oil-water interface was accelerated by using a simple W/O emulsion. Hollow microparticles were obtained when the mole ratio of D2EHPA and calcium in the oil phase was nearly 2:1. The shell formation of the par-ticles depended on ...

  17. 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.

  18. 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...... renal tubule and then discuss why not all gene defects that cause renal tubular acidosis are associated with hypercalciuria and nephrocalcinosis....

  19. Assembly and Calcium Binding Properties of Quantum Dot-Calmodulin Calcium Sensor.

    Science.gov (United States)

    Eun, Su-yong; Nguyen-ta, Kim; Yoo, Hoon; Silva, Gabriel A; Kim, Soon-jong

    2016-02-01

    We have developed the first nanoengineered quantum dot molecular complex designed to measure changes of calcium ion (Ca2+) concentration at high spatial and temporal resolutions in real time. The sensor is ratiometric and composed of three components: a quantum dot (QD) emitting at 620 nm as a fluorescence donor, an organic dye (Alexa Fluor 647) as a fluorescence acceptor, and a calmodulin-M13 (CaM-M13) protein part as a calcium sensing component. In this work, we have determined the maximal number of CaM-M13 required for saturating a single QD particle to be approximately 16. The dissociation constant, Kd of the QD-based calcium ion sensor was also estimated to be around 30 microM. PMID:27433729

  20. Effects of selenium, calcium and calcium ionophore on human oocytes in vitro maturation in a chemically defined medium

    OpenAIRE

    Hessam Roustaei; Mohammad Hasan Fallahian; Fatemeh Peyghambari; Raheleh Aram; Mohammad Ali Sabbaghi; Elham Saboori; Mehri Makki; Abbas Ahmadi

    2012-01-01

    Background: In vitro maturation (IVM) of human oocytes is an emerging procedure quickly incorporated into the world of assisted reproductive technologies. As an effective method of in vitro maturation, several studies have reported the critical role of differentions on activating the complex process involved in both gamete maturation and fertilization. Objective: In this study, we supplemented a chemically defined medium with different combinations of selenium, calcium and calcium ionophore c...

  1. Fruit Calcium: Transport and Physiology

    Science.gov (United States)

    Hocking, Bradleigh; Tyerman, Stephen D.; Burton, Rachel A.; Gilliham, Matthew

    2016-01-01

    Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium

  2. Fruit Calcium: Transport and Physiology.

    Science.gov (United States)

    Hocking, Bradleigh; Tyerman, Stephen D; Burton, Rachel A; Gilliham, Matthew

    2016-01-01

    Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium

  3. Calcium and calcitonin responses to calcium infusion in type I diabetes mellitus.

    OpenAIRE

    Amado, J. A.; C. Gomez; Obaya, S.; Otero, M; Gonzalez-Macias, J

    1987-01-01

    We studied calcium and calcium and calcitonin responses to intravenous calcium infusion (3 mg of elemental calcium/kg of body weight in 10 minutes) in 21 type I diabetic males and 17 age-matched normal males. Baseline total calcium, parathyroid hormone and calcitonin levels were normal in the diabetic group, but ionized calcium was lowered. Cortical bone status and osteocalcin levels were normal, suggesting a normal osteoblastic function. Total calcium and ionized calcium responses to calcium...

  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. Catalytic oxidation of calcium sulfite in solution/aqueous slurry

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-qin; WU Zhong-biao; WANG Da-hui

    2004-01-01

    Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously. Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L, manganese is 10-4 mol/L, and oxygen is of 0.2-0.4 atm.

  6. Reverse calcium affinity purification of Fab with calcium derivatized hydroxyapatite

    OpenAIRE

    Gagnon, Pete; Cheung, Chia-wei; Yazaki, Paul J.

    2009-01-01

    This study introduces the application of calcium-derivatized hydroxyapatite for purification of Fab. Fab binds to native hydroxyapatite but fails to bind to the calcium derivatized form. IgG, Fc, and most other protein contaminants bind to the calcium form. This supports Fab purification by a simple flow-through method that achieves greater than 95% purity from papain digests and mammalian cell culture supernatants. Alternatively, Fab can be concentrated on native hydroxyapatite then eluted s...

  7. T-type calcium channel: a privileged gate for calcium entry and control of adrenal steroidogenesis

    Directory of Open Access Journals (Sweden)

    Michel Florian Rossier

    2016-05-01

    Full Text Available Intracellular calcium plays a crucial role in modulating a variety of functions such as muscle contraction, hormone secretion, gene expression or cell growth. Calcium signaling has been however shown to be more complex than initially thought. Indeed, it is confined within cell microdomains and different calcium channels are associated with different functions, as shown by various channelopathies.Sporadic mutations on voltage-operated L-type calcium channels in adrenal glomerulosa cells have been shown recently to be the second most prevalent genetic abnormalities present in human aldosterone-producing adenoma. The observed modification of the threshold of activation of the mutated channels not only provides an explanation for this gain of function but reminds us on the importance of maintaining adequate electrophysiological characteristics to make channels able to exert specific cellular functions. Indeed, the contribution to steroid production of the various calcium channels expressed in adrenocortical cells is not equal and the reason has been investigated for a long time. Given the very negative resting potential of these cells, and the small membrane depolarization induced by their physiological agonists, low threshold T-type calcium channels are particularly well suited for responding under these conditions and conveying calcium into the cell, at the right place for controlling steroidogenesis. In contrast, high threshold L-type channels are normally activated by much stronger cell depolarizations. The fact that dihydropyridine calcium antagonists, specific for L-type channels, are poorly efficient for reducing aldosterone secretion either in vivo or in vitro, strongly supports the view that these two types of channels differently affect steroid biosynthesis.Whether a similar analysis is transposable to fasciculata cells and cortisol secretion is one of the questions addressed in the present review. No similar mutations on L-type or T

  8. Glycochenodeoxycholic acid inhibits calcium phosphate precipitation in vitro by preventing the transformation of amorphous calcium phosphate to calcium hydroxyapatite.

    OpenAIRE

    Qiu, S M; Wen, G.; Hirakawa, N; Soloway, R D; Hong, N K; Crowther, R S

    1991-01-01

    Calcium hydroxyapatite can be a significant component of black pigment gallstones. Diverse molecules that bind calcium phosphate inhibit hydroxyapatite precipitation. Because glycine-conjugated bile acids, but not their taurine counterparts, bind calcium phosphate, we studied whether glycochenodeoxycholic acid inhibits calcium hydroxyapatite formation. Glycochenodeoxycholic acid (2 mM) totally inhibited transformation of amorphous calcium phosphate microprecipitates to macroscopic crystalline...

  9. Complexity of nearshore strontium-to-calcium ratio variability in a core sample of the massive coral Siderastrea siderea obtained in Coral Bay, St. John, U.S. Virgin Islands

    Science.gov (United States)

    Reich, Christopher D.; Kuffner, Ilsa B.; Hickey, T. Don; Morrison, Jennifer M.; Flannery, Jennifer A.

    2013-01-01

    Strontium-to-calcium ratios (Sr/Ca) were measured on the skeletal matrix of a core sample from a colony of the massive coral Siderastrea siderea collected in Coral Bay, St. John, U.S. Virgin Islands. Strontium and calcium are incorporated into the coral skeleton during the precipitation of aragonite by the coral polyps and their ratio is highly temperature dependent. The robustness of this temperature dependence makes Sr/Ca a reliable proxy for sea surface temperature (SST). Details presented from the St. John S. siderea core indicate that terrestrial inputs of sediment and freshwater can disrupt the chemical balance and subsequently complicate the utility of Sr/Ca in reconstructing historical SST. An approximately 44-year-long record of Sr/Ca shows that an annual SST signal is recorded but with an increasing Sr/Ca trend from 1980 to present, which is likely the result of runoff from the mountainous terrain of St. John. The overwhelming influence of the terrestrial fingerprint on local seawater chemistry makes utilizing Sr/Ca as a SST proxy in nearshore environments very difficult.

  10. Interaction of calcium with sugar type ligands in solutions related to the Bayer process

    OpenAIRE

    Pallagi Attila

    2012-01-01

    The calcium ion (particularly in the form of lime) is one of the most useful processing aids available to alumina refinery operators. In some cases the benefits provided arises through the actions of some soluble form of the calcium cation. Sugar derivatives increase the concentration of the calcium in the liquor phase, therefore investigating their complexation with compounds relevant to the Bayer process (i. e. Ca2+, Al(OH)4−) is important to the industry. Investigating the H+/Gluc– syst...

  11. Calcium – how and why?

    Indian Academy of Sciences (India)

    J K Jaiswal

    2001-09-01

    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 that during the origin and early evolution of life the Ca2+ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.

  12. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Moilanen, A.; Norby, P.; Papadakis, K.; Posselt, D.; Sørensen, L. H.

    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...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...

  13. Calcium Phosphate Biomaterials: An Update

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Current calcium phosphate (CaP) biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite ( HA ) from synthetic or biologic origin, beta-tricalcium phosphate ( β-TCP ) , biphasic calcium phosphate (BCP), and are available as granules, porous blocks, components of composites (CaP/polymer) cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses. This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity, osteoconductivity, osteoinductivity.

  14. 21 CFR 573.240 - Calcium periodate.

    Science.gov (United States)

    2010-04-01

    ... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used...

  15. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does...

  16. Calcium measurement methods

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2010-09-01

    Full Text Available Rightly stressed by prof. Wolfgang Walz in the Preface to the series Neuromethods series, the “careful application of methods is probably the most important step in the process of scientific inquiry”. Thus, I strongly suggest to all those interested in calcium signaling and especially to the new-comers in the hot topic of neuroscience (which has so much space even in science-society debate for its implications in legal issues and in the judge-decision process to take profit from this so well edited book. I am saying this since prof. Verkhratsky and prof. Petersen......

  17. Extracellular calcium sensing and extracellular calcium signaling

    Science.gov (United States)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  18. Casein Phosphopeptide-Amorphous Calcium Phosphate Nanocomplexes: A Structural Model.

    Science.gov (United States)

    Cross, Keith J; Huq, N Laila; Reynolds, Eric C

    2016-08-01

    Tryptic digestion of the calcium-sensitive caseins yields casein phosphopeptides (CPP) that contain clusters of phosphorylated seryl residues. The CPP stabilize calcium and phosphate ions through the formation of complexes. The calcium phosphate in these complexes is biologically available for intestinal absorption and remineralization of subsurface lesions in tooth enamel. We have studied the structure of the complexes formed by the CPP with calcium phosphate using a variety of nuclear magnetic resonance (NMR) techniques. Translational diffusion measurements indicated that the β-CN(1-25)-ACP nanocomplex has a hydrodynamic radius of 1.526 ± 0.044 nm at pH 6.0, which increases to 1.923 ± 0.082 nm at pH 9.0. (1)H NMR spectra were well resolved, and (3)JH(N)-H(α) measurements ranged from a low of 5.5 Hz to a high of 8.1 Hz. Total correlation spectroscopy and nuclear Overhauser effect spectroscopy spectra were acquired and sequentially assigned. Experiments described in this paper have allowed the development of a structural model of the β-CN(1-25)-amorphous calcium phosphate nanocomplex. PMID:27434168

  19. Compartmentalization of the submembrane calcium activity during calcium influx and its significance in transmitter release.

    OpenAIRE

    Simon, S M; Llinás, R R

    1985-01-01

    Quantitative modeling indicates that, in presynaptic terminals, the intracellular calcium concentration profile during inward calcium current is characterized by discrete peaks of calcium immediately adjacent to the calcium channels. This restriction of intracellular calcium concentration suggests a remarkably well specified intracellular architecture such that calcium, as a second messenger, may regulate particular intracellular domains with a great degree of specificity.

  20. Determination of metallic iron in a mixture of lime, calcium sulphide and pyrrhotite.

    Science.gov (United States)

    Sastri, V S

    A method is described for the determination of metallic iron in a complex matrix consisting of calcium oxide, calcium sulphide, carbon and pyrrhotite. The procedure consists of leaching the sample with 5% ammonium chloride solution (10% sucrose solution in some cases) followed by treatment with mercury(II) chloride solution and titration with dichromate solution. PMID:18962353

  1. Women's zinc absorption is unaffected by dietary calcium, with or without high-phytate foods

    Science.gov (United States)

    While some have hypothesized that calcium increases the inhibitory effect of phytic acid on zinc absorption by forming insoluble Ca-Zn-phytate complexes, others have suggested that calcium may competitively bind phytic acid, reducing the phytic acid inhibition of zinc absorption. We tested the influ...

  2. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... Balance › Vitamin D, Calcium, and Bone Health Vitamin D, Calcium, and Bone Health March 2012 Download PDFs ... helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin D ...

  3. 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 ...

  4. Calcium transport in turtle bladder

    International Nuclear Information System (INIS)

    Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa). Ouabain reversed JnetCa to an absorptive flux. Amiloride reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was ≅30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa

  5. An Improved Calcium Flame Test.

    Science.gov (United States)

    Pearson, Robert S.

    1985-01-01

    Indicates that the true red color of calcium can be obtained (using the procedure described by Sorm and Logowski) if the calcium ion solution is mixed with an equal volume of saturated ammonium bromide solution. Suggestions for flame tests of other elements are also noted. (JN)

  6. CALCIUM ENHANCES ANTIINFLAMMATORY ACTIVITY OF ASPIRIN

    OpenAIRE

    Choksi Krishna; Shenoy Ashoka M; A. R. Shabharaya; Lala Minaxi

    2011-01-01

    The objective of present study is to evaluate the effects of calcium carbonate and calcium gluconate on acute and subacute inflammation and to study their possible interactions with Aspirin. Calcium carbonate (10 mg/kg) and calcium gluconate (5 mg/kg) were administered individually and also co-administered along with sub therapeutic dose Aspirin (50mg/kg) to study their interaction. The inflammation was induced by carrageenan or a foreign body. Both calcium carbonate and calcium gluconate cou...

  7. [Role of endoplasmic reticulum-plasma membrane junctions in intracellular calcium homeostasis and cardiovascular disease].

    Science.gov (United States)

    Zhao, Ming; Jia, Hang-Huan; Xu, Man; Yu, Xiao-Jiang; Liu, Long-Zhu; Zang, Wei-Jin

    2016-08-25

    Calcium overload is one of the important mechanisms of cardiovascular disease. Endoplasmic reticulum is an important organelle which regulates intracellular calcium homeostasis by uptake, storage and mobilization of calcium. So it plays a critical role in regulation of intracellular calcium homeostasis. Endoplasmic reticulum, which is widely distributed in cytoplasm, has a large number of membrane junction sites. Recent studies have reported that these junction sites are distributed on plasma membrane and organelle membranes (mitochondria, lysosomes, Golgi apparatus, etc.), separately. They could form complexes to regulate calcium transport. In this review, we briefly outlined the recent research progresses of endoplasmic reticulum-plasma membrane junctions in intracellular calcium homeostasis and cardiovascular disease, which may offer a new strategy for prevention and treatment of cardiovascular disease. PMID:27546511

  8. The role of uncoupling protein 3 regulating calcium ion uptake into mitochondria during sarcopenia

    Science.gov (United States)

    Nikawa, Takeshi; Choi, Inho; Haruna, Marie; Hirasaka, Katsuya; Maita Ohno, Ayako; Kondo Teshima, Shigetada

    Overloaded mitochondrial calcium concentration contributes to progression of mitochondrial dysfunction in aged muscle, leading to sarcopenia. Uncoupling protein 3 (UCP3) is primarily expressed in the inner membrane of skeletal muscle mitochondria. Recently, it has been reported that UCP3 is associated with calcium uptake into mitochondria. However, the mechanisms by which UCP3 regulates mitochondrial calcium uptake are not well understood. Here we report that UCP3 interacts with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that is localized in mitochondria, which is involved in cellular responses to calcium ion. The hydrophilic sequences within the loop 2, matrix-localized hydrophilic domain of mouse UCP3 are necessary for binding to Hax-1 of the C-terminal domain in adjacent to mitochondrial innermembrane. Interestingly, these proteins interaction occur the calcium-dependent manner. Indeed, overexpression of UCP3 significantly enhanced calcium uptake into mitochondria on Hax-1 endogenously expressing C2C12 myoblasts. In addition, Hax-1 knock-down enhanced calcium uptake into mitochondria on both UCP3 and Hax-1 endogenously expressing C2C12 myotubes, but not myoblasts. Finally, the dissociation of UCP3 and Hax-1 enhances calcium uptake into mitochondria in aged muscle. These studies identify a novel UCP3-Hax-1 complex regulates the influx of calcium ion into mitochondria in muscle. Thus, the efficacy of UCP3-Hax-1 in mitochondrial calcium regulation may provide a novel therapeutic approach against mitochondrial dysfunction-related disease containing sarcopenia.

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

    International Nuclear Information System (INIS)

    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 and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction

  10. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  11. Nicotinic acetylcholine receptor-mediated calcium signaling in the nervous system

    Institute of Scientific and Technical Information of China (English)

    Jian-xin SHEN; Jerrel L YAKEL

    2009-01-01

    Based on the composition of the five subunits forming functional neuronal nicotinic acetylcholine receptors (nAChRs), they are grouped into either heteromeric (comprising both α and β subunits) or homomeric (comprising only α subunits) recep-tors. The nAChRs are known to be differentially permeable to calcium ions, with the α7 nAChR subtype having one of the highest permeabilities to calcium. Calcium influx through nAChRs, particularly through the α-bungarotoxin-sensitive α7-containing nAChRs, is a very efficient way to raise cytoplasmic calcium levels. The activation of nAChRs can mediate three types of cytoplasmic calcium signals: (1) direct calcium influx through the nAChRs, (2) indirect calcium influx through voltage-dependent calcium channels (VDCCs) which are activated by the nAChR-mediated depolarization, and (3) calcium-induced calcium release (CICR) (triggered by the first two sources) from the endoplasmic reticulum (ER) through the ryanodine receptors and inositol (1,4,5)-triphosphate receptors (IP3Rs). Downstream signaling events mediated by nAChR-mediated calcium responses can be grouped into instantaneous effects (such as neurotransmitter release, which can occur in milliseconds after nAChR activation), short-term effects (such as the recovery of nAChR desensitization through cellular signaling cascades), and long-term effects (such as neuroprotection via gene expression). In addition, nAChR activity can be regulated by cytoplasmic calcium levels, suggesting a complex reciprocal relationship. Further advances in imaging techniques, animal models, and more potent and subtype-selective ligands for neuronal nAChRs would help in understand-ing the neuronal nAChR-mediated calcium signaling, and lead to the development of improved therapeutic treatments.

  12. 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.

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

    OpenAIRE

    Samigullin, Dmitry; Fatikhov, Nijaz; Khaziev, Eduard; Skorinkin, Andrey; Nikolsky, Eugeny; Bukharaeva, Ellya

    2015-01-01

    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 dy...

  14. Casein Phosphopeptide- Amorphous Calcium Phosphate in Dentistry: A Literature Review

    OpenAIRE

    KESKİN, Arş. Gör. Dt. Gül; GÜLER, Yrd. Doç. Dr. Çiğdem

    2013-01-01

    Casein is a phosphoprotein in bovine milk and accounts for almost 80 percent of its total protein. Casein fosfopeptit (CPP) is produced as a result of decomposition of casein with trypsin enzyme using a selective deposition method. CPP can remarkably stabilize calcium phosphate in a state-forming CPPamorphous calcium phosphate (ACP) complex. CPPACP is located in topical gels, sugar-free chewing gum and mint dragees at the present day. In this paper, the effectiveness of CPP-ACP and usage in d...

  15. Variability of calcium absorption

    International Nuclear Information System (INIS)

    Variability in calcium absorption was estimated in three groups of normal subjects in whom Ca absorption was measured by standard isotopic-tracer methods at interstudy intervals ranging from 1 to 4 mo. Fifty absorption tests were performed in 22 subjects. Each was done in the morning after an overnight fast with an identical standard breakfast containing a Ca load of approximately 250 mg. Individual fractional absorption values were normalized to permit pooling of the data. The coefficient of variation (CVs) for absorption for the three groups ranged from 10.57 to 12.79% with the size of the CV increasing with interstudy duration. One other published study presenting replicate absorption values was analyzed in a similar fashion and was found to have a CV of absorption of 9.78%. From these data we estimate that when the standard double-isotope method is used to measure Ca absorption there is approximately 10% variability around any given absorption value within an individual human subject and that roughly two-thirds of this represents real biological variability in absorption

  16. Monitoring the intracellular calcium response to a dynamic hypertonic environment

    Science.gov (United States)

    Huang, Xiaowen; Yue, Wanqing; Liu, Dandan; Yue, Jianbo; Li, Jiaqian; Sun, Dong; Yang, Mengsu; Wang, Zuankai

    2016-03-01

    The profiling of physiological response of cells to external stimuli at the single cell level is of importance. Traditional approaches to study cell responses are often limited by ensemble measurement, which is challenging to reveal the complex single cell behaviors under a dynamic environment. Here we report the development of a simple microfluidic device to investigate intracellular calcium response to dynamic hypertonic conditions at the single cell level in real-time. Interestingly, a dramatic elevation in the intracellular calcium signaling is found in both suspension cells (human leukemic cell line, HL-60) and adherent cells (lung cancer cell line, A549), which is ascribed to the exposure of cells to the hydrodynamic stress. We also demonstrate that the calcium response exhibits distinct single cell heterogeneity as well as cell-type-dependent responses to the same stimuli. Our study opens up a new tool for tracking cellular activity at the single cell level in real time for high throughput drug screening.

  17. A novel hydrolytic product from flesh of Mactra veneriformis and its bioactivities in calcium supplement

    Science.gov (United States)

    Wang, Lingchong; Chen, Shiyong; Liu, Rui; Wu, Hao

    2012-09-01

    To prepare calcium-binding peptides, the flesh residue of Mactra Veneriformis was subjected to enzymatic hydrolysis. By comparing the capability of combining calcium of the hydrolyzates, pepsin was confirmed to be the most suitable enzyme for hydrolyzing the flesh residue to release calcium-binding peptides among the seven tested proteases. The pepsin hydrolyzate (PHM) was divided into three fractions according to the molecule weight of its composition, which ranged from 0.5 to 15 kDa. The low-molecule-weight fraction named PHM-3 had the highest capability in combining calcium. The peptides existing in the PHM-3 fraction consisted of higher contents of Glu, Ala and Leu, and could produce one type of calcium-peptide complex by powerfully chelating calcium ions. PHM-3 products could effectively increase calcium absorption and retention while they decreased the calcium excretion in animal tests. Additionally, symptoms caused by low calcium bioavailability in ovariectomized rats, such as bone mineral density reduction and mechanical strength loss could be significantly ameliorated by the hydrolytic products addition in diet.

  18. A Novel Hydrolytic Product from Flesh of Mactra veneriformis and Its Bioactivities in Calcium Supplement

    Institute of Scientific and Technical Information of China (English)

    WANG Lingchong; CHEN Shiyong; LIU Rui; WU Hao

    2012-01-01

    To prepare calcium-binding peptides,the flesh residue of Mactra Veneriformis was subjected to enzymatic hydrolysis.By comparing the capability of combining calcium of the hydrolyzates,pepsin was confirmed to be the most suitable enzyme for hydrolyzing the flesh residue to release calcium-binding peptides among the seven tested proteases.The pepsin hydrolyzate(PHM)was divided into three fractions according to the molecule weight of its composition,which ranged from 0.5 to 15 kDa.The low-molecule-weight fraction named PHM-3 had the highest capability in combining calcium.The peptides existing in the PHM-3fraction consisted of higher contents of Glu,Ala and Leu,and could produce one type of calcium-peptide complex by powerfully chelating calcium ions.PHM-3 products could effectively increase calcium absorption and retention while they decreased the calcium excretion in animal tests.Additionally,symptoms caused by low calcium bioavailability in ovariectomized rats,such as bone mineral density reduction and mechanical strength loss could be significantly ameliorated by the hydrolytic products addition in diet.

  19. Investigation of calcium phosphate coatings for biomedical applications

    International Nuclear Information System (INIS)

    Calcium phosphate is the main constituent of our bone and tooth minerals. The use of this bioactive material for coating implant such as artificial joint prosthesis, therefore, can promote biological fixation and enhance biocompatibility. Our initial work has been focused on the evaluation of experimental conditions of coating preparation and the effects of post-deposition calcium phosphate coatings on stainless steel substrates. The coating layers were produced by the precipitation technique and coatings were carried out in sol-gel by the dipping method. For comparison purposes a wet method was used to obtain a fine calcium phosphate ceramic powder for fabrication of microcrystal suspension used as a coating material. Scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), energy dispersive x-ray fluorescence (EDXRF) and x-ray diffraction (XRD) were used to characterise the morphology, chemical composition and structure of the coatings. The results showed that the dip coating of stainless steel substrates using viscous solutions lead to the formation of porous calcium phosphate layers. These results suggested that fabrication of bioactive calcium phosphate coatings using this route offers significant advantages over the currently used methods due to considerably lower temperature process involved and may produce better result for substrates with complex shapes

  20. Emanuel Strehler’s work on calcium pumps and calcium signaling

    Institute of Scientific and Technical Information of China (English)

    Emanuel; E; Strehler

    2011-01-01

    Cells are equipped with mechanisms to control tightly the influx, efflux and resting level of free calcium (Ca 2+ ). Inappropriate Ca 2+ signaling and abnormal Ca 2+ levels are involved in many clinical disorders including heart disease, Alzheimer’s disease and stroke. Ca 2+ also plays a major role in cell growth, differentiation and motility; disturbances in these processes underlie cell transformation and the progression of cancer. Accordingly, research in the Strehler laboratory is focused on a better understanding of the molecular "toolkit" needed to ensure proper Ca 2+ homeostasis in the cell, as well as on the mechanisms of localized Ca 2+ signaling. A longterm focus has been on the plasma membrane calcium pumps (PMCAs), which are linked to multiple disorders including hearing loss, neurodegeneration, and heart disease. Our work over the past 20 years or more has revealed a surprising complexity of PMCA isoforms with different functional characteristics, regulation, and cellular localization. Emerging evidence shows how specific PMCAs contribute not only to setting basal intracellular Ca 2+ levels, but also to local Ca 2+ signaling and vectorial Ca 2+ transport. A second major research arearevolves around the calcium sensor protein calmodulin and an enigmatic calmodulin-like protein (CALML3) that is linked to epithelial differentiation. One of the cellular targets of CALML3 is the unconventional motor protein myosin-10, which raises new questions about the role of CALML3 and myosin-10 in cell adhesion and migration in normal cell differentiation and cancer.

  1. "Caged calcium" in Aplysia pacemaker neurons. Characterization of calcium-activated potassium and nonspecific cation currents

    OpenAIRE

    1989-01-01

    We have studied calcium-activated potassium current, IK(Ca), and calcium-activated nonspecific cation current, INS(Ca), in Aplysia bursting pacemaker neurons, using photolysis of a calcium chelator (nitr-5 or nitr-7) to release "caged calcium" intracellularly. A computer model of nitr photolysis, multiple buffer equilibration, and active calcium extrusion was developed to predict volume-average and front-surface calcium concentration transients. Changes in arsenazo III absorbance were used to...

  2. Effect of Preharvest Calcium Treatments on Sweet Cherry Fruit Quality

    OpenAIRE

    Deniz EROGUL

    2014-01-01

    In this study, the effects of different foliar calcium compounds on fruit cracking and quality of sweet cherry variety ‘0900 Ziraat’ were investigated. Calcium caseinate, calcium chloride, calcium hydroxide and calcium nitrate were used as foliar sprays. Calcium applications reduced the cracking index 38% to 66% compared to cherries that did not receive foliar treatment. The most efficient applications for decreasing cracking were calcium hydroxide and calcium chloride. Calcium chloride and c...

  3. Stochastic Simulation of Cardiac Ventricular Myocyte Calcium Dynamics and Waves

    OpenAIRE

    Tuan, Hoang-Trong Minh; Williams, George S.B.; Chikando, Aristide C.; Sobie, Eric A.; Lederer, W. Jonathan; Jafri, M. Saleet

    2011-01-01

    A three dimensional model of calcium dynamics in the rat ventricular myocyte was developed to study the mechanism of calcium homeostasis and pathological calcium dynamics during calcium overload. The model contains 20,000 calcium release units (CRUs) each containing 49 ryanodine receptors. The model simulates calcium sparks with a realistic spontaneous calcium spark rate. It suggests that in addition to the calcium spark-based leak, there is an invisible calcium leak caused by the stochastic ...

  4. Aging and calcium as an environmental factor.

    Science.gov (United States)

    Fujita, T

    1985-12-01

    Calcium deficiency is a constant menace to land-abiding animals, including mammals. Humans enjoying exceptional longevity on earth are especially susceptible to calcium deficiency in old age. Low calcium and vitamin D intake, short solar exposure, decreased intestinal absorption, and falling renal function with insufficient 1,25(OH)2 vitamin D biosynthesis all contribute to calcium deficiency, secondary hyperparathyroidism, bone loss and possibly calcium shift from the bone to soft tissue, and from the extracellular to the intracellular compartment, blunting the sharp concentration gap between these compartments. The consequences of calcium deficiency might thus include not only osteoporosis, but also arteriosclerosis and hypertension due to the increase of calcium in the vascular wall, amyotrophic lateral sclerosis and senile dementia due to calcium deposition in the central nervous system, and a decrease in cellular function, because of blunting of the difference in extracellular-intracellular calcium, leading to diabetes mellitus, immune deficiency and others (Fig. 6). PMID:2943880

  5. Optimizing calcium selective fluorimetric nanospheres.

    Science.gov (United States)

    Kisiel, Anna; Kłucińska, Katarzyna; Gniadek, Marianna; Maksymiuk, Krzysztof; Michalska, Agata

    2015-11-01

    Recently it was shown that optical nanosensors based on alternating polymers e.g. poly(maleic anhydride-alt-1-octadecene) were characterized by a linear dependence of emission intensity on logarithm of concentration over a few of orders of magnitude range. In this work we focus on the material used to prepare calcium selective nanosensors. It is shown that alternating polymer nanosensors offer competitive performance in the absence of calcium ionophore, due to interaction of the nanospheres building blocks with analyte ions. The emission increase corresponds to increase of calcium ions contents in the sample within the range from 10(-4) to 10(-1) M. Further improvement in sensitivity (from 10(-6) to 10(-1) M) and selectivity can be achieved by incorporating calcium ionophore in the nanospheres. The optimal results were obtained for core-shell nanospheres, where the core was prepared from poly(styrene-co-maleic anhydride) and the outer layer from poly(maleic anhydride-alt-1-octadecene). Thus obtained chemosensors were showing linear dependence of emission on logarithm of calcium ions concentration within the range from 10(-7) to 10(-1) M. PMID:26452839

  6. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    International Nuclear Information System (INIS)

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca9Sr(PO4)6(OH)2 - CaSr9(PO4)6(OH)2. The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice

  7. Effect of anions or foods on absolute bioavailability of calcium from calcium salts in mice by pharmacokinetics

    OpenAIRE

    Ueda, Yukari; Taira, Zenei

    2013-01-01

    We studied the absolute bioavailability of calcium from calcium L-lactate in mice using pharmacokinetics, and reviewed the absolute bioavailability of calcium from three other calcium salts in mice previously studied: calcium chloride, calcium acetate, and calcium ascorbate. The results showed that calcium metabolism is linear between intravenous administration of 15 mg/kg and 30 mg/kg, and is not affected by anions. Results after oral calcium administration of 150 mg/kg showed that the intes...

  8. Calcium release-activated calcium current in rat mast cells.

    Science.gov (United States)

    Hoth, M; Penner, R

    1993-06-01

    1. Whole-cell patch clamp recordings of membrane currents and fura-2 measurements of free intracellular calcium concentration ([Ca2+]i) were used to study the biophysical properties of a calcium current activated by depletion of intracellular calcium stores in rat peritoneal mast cells. 2. Calcium influx through an inward calcium release-activated calcium current (ICRAC) was induced by three independent mechanisms that result in store depletion: intracellular infusion of inositol 1,4,5-trisphosphate (InsP3) or extracellular application of ionomycin (active depletion), and intracellular infusion of calcium chelators (ethylene glycol bis-N,N,N',N'-tetraacetic acid (EGTA) or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA)) to prevent reuptake of leaked-out calcium into the stores (passive depletion). 3. The activation of ICRAC induced by active store depletion has a short delay (4-14 s) following intracellular infusion of InsP3 or extracellular application of ionomycin. It has a monoexponential time course with a time constant of 20-30 s and, depending on the complementary Ca2+ buffer, a mean normalized amplitude (at 0 mV) of 0.6 pA pF-1 (with EGTA) and 1.1 pA pF-1 (with BAPTA). 4. After full activation of ICRAC by InsP3 in the presence of EGTA (10 mM), hyperpolarizing pulses to -100 mV induced an instantaneous inward current that decayed by 64% within 50 ms. This inactivation is probably mediated by [Ca2+]i, since the decrease of inward current in the presence of the fast Ca2+ buffer BAPTA (10 mM) was only 30%. 5. The amplitude of ICRAC was dependent on the extracellular Ca2+ concentration with an apparent dissociation constant (KD) of 3.3 mM. Inward currents were nonsaturating up to -200 mV. 6. The selectivity of ICRAC for Ca2+ was assessed by using fura-2 as the dominant intracellular buffer (at a concentration of 2 mM) and relating the absolute changes in the calcium-sensitive fluorescence (390 nm excitation) with the calcium current integral

  9. Calcium phosphate in catheter encrustation.

    Science.gov (United States)

    Cox, A J; Harries, J E; Hukins, D W; Kennedy, A P; Sutton, T M

    1987-02-01

    Encrusted catheters from nine female patients were the source of samples of deposits which were examined by X-ray diffraction, atomic absorption spectroscopy, infra-red spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. In eight samples the only crystalline phase which could be clearly distinguished by X-ray diffraction was ammonium magnesium orthophosphate hexahydrate, NH4MgPO4 X 6H2O, which occurs naturally as the mineral struvite. However, atomic absorption spectroscopy revealed an appreciable concentration of calcium in all samples. Calcium phosphates have previously been detected in catheter deposits. Infra-red and EXAFS spectra were consistent with the calcium phosphate being present as a poorly crystalline hydroxyapatite. Thus the deposits appear to consist of a mixture of crystalline struvite and a form of hydroxyapatite which is not fully crystalline. PMID:3030487

  10. The effect of variable calcium and very low calcium diets on human calcium metabolism. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Chu, J.

    1971-01-01

    The effects of a very low calcium diet, with variable high and low protein intake, on the dynamics of calcium metabolism and the mechanism of calciuretics, are examined. The experiment, using male subjects, was designed to study the role of intestinal calcium absorption on urinary calcium excretion, and the rate of production of endogeneously secreted calcium in the gastrointestinal tract. The study showed an average of 70% fractional absorption rate during very low calcium intake, and that a decrease in renal tubular reabsorption of calcium is responsible for calciuretic effects of high protein intake. The study also indicates that there is a tendency to develop osteoporosis after long periods of low calcium intake, especially with a concurrent high protein intake.

  11. Tumoral calcium pyrophosphate deposition disease

    International Nuclear Information System (INIS)

    A report of two patients in which a soft tissue mass, initially regarded as a malignant tumor, was shown to be the result of calcium pyrophosphate deposition disease. The first case, a woman aged 71 years, presented with a mass involving the right fifth finger. In the second case, also a women aged 71 years, the lesion involved the tissues adjacent to the right hip. Each lesion consisted of a mass of highly cellular tissue containing deposits of calcium pyrophosphate dihydrate crystals. The clinical, radiological, and pathological features of the two cases are compared with those of seven similar cases reported in the literature. (orig.)

  12. 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

  13. Diffusive spatio-temporal noise in a first-passage time model for intracellular calcium release

    KAUST Repository

    Flegg, Mark B.

    2013-01-01

    The intracellular release of calcium from the endoplasmic reticulum is controlled by ion channels. The resulting calcium signals exhibit a rich spatio-temporal signature, which originates at least partly from microscopic fluctuations. While stochasticity in the gating transition of ion channels has been incorporated into many models, the distribution of calcium is usually described by deterministic reaction-diffusion equations. Here we test the validity of the latter modeling approach by using two different models to calculate the frequency of localized calcium signals (calcium puffs) from clustered IP3 receptor channels. The complexity of the full calcium system is here limited to the basic opening mechanism of the ion channels and, in the mathematical reduction simplifies to the calculation of a first passage time. Two models are then studied: (i) a hybrid model, where channel gating is treated stochastically, while calcium concentration is deterministic and (ii) a fully stochastic model with noisy channel gating and Brownian calcium ion motion. The second model utilises the recently developed two-regime method [M. B. Flegg, S. J. Chapman, and R. Erban, "The two-regime method for optimizing stochastic reaction-diffusion simulations," J. R. Soc., Interface 9, 859-868 (2012)] in order to simulate a large domain with precision required only near the Ca2+ absorbing channels. The expected time for a first channel opening that results in a calcium puff event is calculated. It is found that for a large diffusion constant, predictions of the interpuff time are significantly overestimated using the model (i) with a deterministic non-spatial calcium variable. It is thus demonstrated that the presence of diffusive noise in local concentrations of intracellular Ca2+ ions can substantially influence the occurrence of calcium signals. The presented approach and results may also be relevant for other cell-physiological first-passage time problems with small ligand concentration

  14. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Devkanya Dutta

    2000-12-01

    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 store-operated calcium entry or capacitative calcium entry. Capacitative calcium current plays a key role in replenishing calcium stores and activating various physiological processes. Despite considerable efforts, very little is known about the molecular nature of the capacitative channel and the signalling pathway that activates it. This review summarizes our current knowledge about store operated calcium entry and suggests possible hypotheses for its mode of activation.

  15. Dairy Dilemma: Are You Getting Enough Calcium?

    Science.gov (United States)

    ... Dairy Dilemma Dairy Dilemma Are You Getting Enough Calcium? You may be avoiding dairy products because of ... But dairy products are a major source of calcium, vitamin D and other nutrients that are important ...

  16. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... can break easily, even without an obvious injury. Vitamin D helps your body absorb calcium. Eat foods that provide the right amounts of calcium, vitamin D, and protein. This kind of diet will give ...

  17. COMPLEX COMPOST AND DETOXICATION OF AGROLANDSCAPE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Belyuchenko I. S.

    2014-03-01

    Full Text Available Toxicity complex compost arises during compiling of organomineral mixtures of various waste of life, agriculture and mineral industries. One of detoxification factors of complex compost is the ability of heavy metal cations to the formation insoluble compounds, which are fixed by clay materials and different disperse systems, and differ markedly by calcium content, acidity and humus soil-absorbing complex

  18. Calcium channel blockers and Alzheimer's disease

    Institute of Scientific and Technical Information of China (English)

    Yi Tan; Yulin Deng; Hong Qing

    2012-01-01

    Alzheimer's disease is characterized by two pathological hallmarks: amyloid plaques and neurofi-brillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging. Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer's disease. Calcium channel blockers are effective therapeutics for treating Alzheimer's disease. This review provides an overview of the current research of calcium channel blockers in-volved in Alzheimer's disease therapy.

  19. Calcium channel blockers and Alzheimer's disease★

    OpenAIRE

    Tan, Yi; Deng, Yulin; Qing, Hong

    2012-01-01

    Alzheimer's disease is characterized by two pathological hallmarks: amyloid plaques and neurofibrillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging. Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer's disease. Calcium channel blockers are effective therapeutics for treating Alzheimer's disease. This review provides an overview of the current research of calcium channel blockers involved in...

  20. Teaching Calcium-Induced Calcium Release in Cardiomyocytes Using a Classic Paper by Fabiato

    Science.gov (United States)

    Liang, Willmann

    2008-01-01

    This teaching paper utilizes the materials presented by Dr. Fabiato in his review article entitled "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum." In the review, supporting evidence of calcium-induced calcium release (CICR) is presented. Data concerning potential objections to the CICR theory are discussed as well. In…

  1. Electrophysical properties of calcium orthovanadate

    International Nuclear Information System (INIS)

    The electron conductivity, dielectric permeability and magnetic susceptibility of calcium orthovanadate are studied. It is shown that structural transformations bring about changes in the nature of electrophysical properties of Ca3(VO4)2 and cause the charge redistribution in VO43- anion groups

  2. Multimodal encoding in a simplified model of intracellular calcium signaling

    OpenAIRE

    De Pitta`, Maurizio; Volman, Vladislav; Levine, Herbert; Ben-Jacob, Eshel

    2009-01-01

    Many cells use calcium signalling to carry information from the extracellular side of the plasma membrane to targets in their interior. Since virtually all cells employ a network of biochemical reactions for Ca2+ signalling, much effort has been devoted to understand the functional role of Ca2+ responses and to decipher how their complex dynamics is regulated by the biochemical network of Ca2+-related signal transduction pathways. Experimental observations show that Ca2+ signals in response t...

  3. 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)....

  4. 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)....

  5. 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... Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  6. 21 CFR 582.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 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... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  7. 21 CFR 582.5191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 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... Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  8. 21 CFR 73.1070 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine,...

  9. 21 CFR 582.1205 - Calcium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium hydroxide. 582.1205 Section 582.1205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1205 Calcium hydroxide. (a) Product. Calcium hydroxide. (b) Conditions of use....

  10. 21 CFR 182.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2227 Calcium silicate. (a) Product. Calcium silicate....

  11. 21 CFR 582.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  12. Calcium dynamics in vascular smooth muscle

    OpenAIRE

    Amberg, Gregory C.; Navedo, Manuel F.

    2013-01-01

    Smooth muscle cells are ultimately responsible for determining vascular luminal diameter and blood flow. Dynamic changes in intracellular calcium are a critical mechanism regulating vascular smooth muscle contractility. Processes influencing intracellular calcium are therefore important regulators of vascular function with physiological and pathophysiological consequences. In this review we discuss the major dynamic calcium signals identified and characterized in vascular smooth muscle cells....

  13. Lactulose stimulates calcium absorption in postmenopausal women

    NARCIS (Netherlands)

    Heuvel, E.G.H.M. van den; Muijs, T.; Dokkum, W. van; Schaafsma, G.

    1999-01-01

    Animal studies have indicated that calcium absorption is increased by lactulose, a synthetic disaccharide. Therefore, the influence of lactulose on calcium absorption was measured in postmenopausal women who may benefit from the possible enhancing effect of lactulose on calcium absorption. Twelve po

  14. Investigations of nano coated calcium hydroxide cycled in a thermochemical heat storage

    OpenAIRE

    Roßkopf, Christian; Afflerbach, Sandra; Schmidt, Matthias; Görtz, Burkhard; Torsten, Kowald; Linder, Marc; Reinhard, Trettin

    2015-01-01

    Thermochemical heat storage systems are a promising new technology for concentrated solar power plants and can contribute to improve the efficiency of industrial processes Neveu et al. (2013) [21]. However, for example for the reaction system calcium oxide/calcium hydroxide (CaO/Ca(OH)2), the good availability at low cost is accompanied by poor powder properties that demand complex reactor solutions. During thermochemical cycling agglomeration effects occur and originate inhomogeneity resulti...

  15. Calcium in the initiation, progression and as an effector of Alzheimer’s disease pathology

    OpenAIRE

    Green, Kim N.

    2009-01-01

    The cause(s) of sporadic Alzheimer’s disease (sAD) are complex and currently poorly understood. They likely result from a combination of genetic, environmental, proteomic and lipidomic factors that crucially occur only in the aged brain. Age-related changes in calcium levels and dynamics have the potential to increase the production and accumulation of both amyloid-β peptide (Aβ) and τ pathologies in the AD brain, although these two pathologies themselves can induce calcium dyshomeostasis, pa...

  16. Sodium/Calcium Exchangers Selectively Regulate Calcium Signaling in Mouse Taste Receptor Cells

    OpenAIRE

    Szebenyi, Steven A.; Laskowski, Agnieszka I.; Medler, Kathryn F.

    2010-01-01

    Taste cells use multiple signaling mechanisms to generate appropriate cellular responses to discrete taste stimuli. Some taste stimuli activate G protein coupled receptors (GPCRs) that cause calcium release from intracellular stores while other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). While the signaling mechanisms that initiate calcium signals have been described in taste cells, the calcium clearance mechanisms (CCMs) that contrib...

  17. 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...... offers several advantages over standard treatment options: calcium is inexpensive and may readily be applied without special precautions, as is the case with cytostatic drugs. Therefore, details on the use of calcium electroporation are essential for carrying out clinical trials comparing calcium...... electroporation and electrochemotherapy. METHODS: The effects of calcium electroporation and bleomycin electroporation (alone or in combination) were compared in three different cell lines (DC-3F, transformed Chinese hamster lung fibroblast; K-562, human leukemia; and murine Lewis Lung Carcinoma). Furthermore...

  18. Effect of anions or foods on absolute bioavailability of calcium from calcium salts in mice by pharmacokinetics

    OpenAIRE

    Zenei Taira, Zenei

    2013-01-01

    Yukari Ueda, Zenei TairaFaculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, JapanAbstract: We studied the absolute bioavailability of calcium from calcium L-lactate in mice using pharmacokinetics, and reviewed the absolute bioavailability of calcium from three other calcium salts in mice previously studied: calcium chloride, calcium acetate, and calcium ascorbate. The results showed that calcium metabolism is linear between intravenous administration of 15 mg/kg and 30 ...

  19. Calcium signals and calcium channels in osteoblastic cells

    Science.gov (United States)

    Duncan, R. L.; Akanbi, K. A.; Farach-Carson, M. C.

    1998-01-01

    Calcium (Ca2+) channels are present in non-excitable as well as in excitable cells. In bone cells of the osteoblast lineage, Ca2+ channels play fundamental roles in cellular responses to external stimuli including both mechanical forces and hormonal signals. They are also proposed to modulate paracrine signaling between bone-forming osteoblasts and bone-resorbing osteoclasts at local sites of bone remodeling. Calcium signals are characterized by transient increases in intracellular Ca2+ levels that are associated with activation of intracellular signaling pathways that control cell behavior and phenotype, including patterns of gene expression. Development of Ca2+ signals is a tightly regulated cellular process that involves the concerted actions of plasma membrane and intracellular Ca2+ channels, along with Ca2+ pumps and exchangers. This review summarizes the current state of knowledge concerning the structure, function, and role of Ca2+ channels and Ca2+ signals in bone cells, focusing on the osteoblast.

  20. 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.

  1. Substitution of calcium by strontium within selected calcium phosphates

    Science.gov (United States)

    Rokita, E.; Hermes, C.; Nolting, H.-F.; Ryczek, J.

    1993-06-01

    Sr incorporation in the molecules of amorphous calcium phosphate, apatitic tricalcium phosphate, hydroxyapatite, octacalcium phosphate and dicalcium phosphate dihydrate was investigated. The concentration of Sr ranged from 225 to 1010 μ g / g, i.e. it overlapped with the physiological range of Sr concentrations in human bone. The leading experimental technique was extended X-ray absorption fine structure (EXAFS) at the Sr K edge. Results of these studies demonstrated the following: (1) Sr incorporation in the calcium phosphates is compound-dependent, (2) the coordination of incorporated Sr atoms in the Ca-P molecules is similar to that of Ca atoms, but interatomic distances are ≈0.015 nm larger, (3) in apatitic tricalcium phosphate, hydroxyapatite and octacalcium phosphate lattices Sr atoms may occupy selected Ca sites, which was not the case for dicalcium phosphate dihydrate, (4) in the apatite lattice Sr atoms are coordinated by 6 PO 4 tetrahedrals and (5) EXAFS spectra at the K edge of the incorporated Sr may be used to distinguish the structures of amorphous calcium phosphate, dicalcium phosphate dihydrate as well as apatite and its derivatives (apatitic tricalcium phosphate, octacalcium phosphate).

  2. USING CALCIUM CARBONATE WHISKERS AS PAPERMAKING FILLER

    Directory of Open Access Journals (Sweden)

    Xiaoyu Chen

    2011-05-01

    Full Text Available Whiskers, having large length/diameter ratio, are fiber-shaped single crystals. The technical possibility of using calcium carbonate whiskers as papermaking filler to replace conventional powder-like calcium carbonate was investigated. The results showed that it may be feasible to use calcium carbonate whisker as papermaking filler. Compared with conventional precipitated calcium carbonate, calcium carbonate whisker had higher retention efficiency. The use of calcium carbonate whisker also favorably affected the strength properties of paper sheets. A model was proposed to suggest the mechanism for paper strength improvement. The whiskers filled in paper sheets could increase the friction between fibers, thus increasing bonding strength. Moreover, the strength properties of paper were further improved because calcium carbonate whiskers were partly embedded in pulp fiber walls.

  3. CALCIUM ENHANCES ANTIINFLAMMATORY ACTIVITY OF ASPIRIN

    Directory of Open Access Journals (Sweden)

    Choksi Krishna

    2011-03-01

    Full Text Available The objective of present study is to evaluate the effects of calcium carbonate and calcium gluconate on acute and subacute inflammation and to study their possible interactions with Aspirin. Calcium carbonate (10 mg/kg and calcium gluconate (5 mg/kg were administered individually and also co-administered along with sub therapeutic dose Aspirin (50mg/kg to study their interaction. The inflammation was induced by carrageenan or a foreign body. Both calcium carbonate and calcium gluconate could not show significant anti-inflammatory activity on their own in acute as well as subacute inflammation models. Aspirin at sub-anti-inflammatory dose (50mg/Kg when co-administered along with calcium salts produced the significant anti-inflammatory response which was comparable to anti-inflammatory response of aspirin at therapeutic dose (200mg/Kg. Also co-adminostration minimized the gastro-toxicity of aspirin.

  4. Removal of plutonium by a new type calcium and combination of the calcium and Ca-DTPA in rats

    International Nuclear Information System (INIS)

    Effects of a new type of calcium product (Seaweed-calcium complex: SWCa) and combination of SWCa and Ca-DTPA on removal of injected 239Pu were examined in rats. SWCa is a natural product consisting of mixed calcined oyster shell (COS) which is composed of calcium salt probably in the form of calcium oxide and a natural material extracted from seaweed to transport calcium actively throughout the small intestine. In experiment I, a 2% solution of SWCa, COS, CaO, CaCl2 or CaCO3 was injected into the small intestinal loops of rats to compare the intestinal absorption rate of each calcium salt. In experiment II, 25 male Wistar rats were divided into five groups give; a control diet with 1% CaCO3 (group A), a SWCa diet with 1% SWCa to replace the 1% CaCO3 after Pu injection (group B), a SWCa diet 1 week before Pu injection until the end of the experiment (group C), a SWCa diet and intraperitoneal injections of a daily dose of 150 μmol/kg of Ca-DTPA (group D), and a control diet and intraperitoneal injections of the same dose of Ca-DTPA as group D (group E). The rats were injected intravenously with Pu, 1.85x104 Bq/kg, and killed 14 days later. The Pu concentration was measured by a liquid scintillation spectrometry after a wet ashing treatment. The levels of serum total and ionic calcium were elevated more rapidly and were higher after the injection of SWCa than after those of COS, CaO and CaCO3. The percent of Pu content to administered dose in the skeleton was 69.3, 63.6, 58.8, 10.4 and 19.0% and that in the liver was 7.74, 6.93, 6.43, 0.22 and 0.35% for groups A, B, C, D and E, respectively. The Pu contents in the urine and feces were increased during the first 2-3 days after Pu injection in the SWCa groups. The elevation of serum calcium by oral administration of SWCa could lower the Pu content in the skeleton and liver both before and after Pu injection and the effects were increased by the combination of SWCa and Ca-DTPA. (author)

  5. [Calcium pyrophosphate dihydrate deposition disease].

    Science.gov (United States)

    Koitschev, C; Kaiserling, E; Koitschev, A

    2003-08-01

    Calcium pyrophosphate dihydrate deposition disease (CPPD) of the temporomandibular joint is rare. The disorder is characterized by the presence of crystal deposits within the affected joint. The deposition of crystals in adjacent soft tissue may lead to the formation of pseudotumors. This form of the disease is called tophaceous pseudogout and typically affects the temporomandibular joint. It is difficult to differentiate the disease, particularly from malignant tumors, on the clinical and radiographic findings alone. The diagnosis is based on histological identification of the calcium pyrophosphate crystals. We present an unusually advanced case of tophaceous pseudogout of the temporomandibular joint. The etiology, clinical and diagnostic criteria as well as treatment options are discussed on the basis of our own experience and a review of the literature. PMID:12942180

  6. 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....

  7. Serum calcium in pulmonary tuberculosis

    OpenAIRE

    Subhash C. Sharma

    1981-01-01

    Serum calcium was studied serially in 94 patients with active pulmonary tuberculosis. An equal number of age- and sex-matched patients with chronic obstructive pulmonary disease were controls. Seventy patients in the study group were normocalcaemic and 10 were hypercalcaemic. These 10 were on a higher supplement of vitamin D than the 70 normocalcaemic patients. There was a positive correlation between the daily vitamin intake and the degree and duration of hypercalcaemia. None of the controls...

  8. Drying dichloromethane over calcium hydride

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Lucas Kinard, Kurtis Kasper & Antonios Mikos ### Abstract This protocol describes the drying of dichloromethane by a simple 10 step procedure. One can implement this protocol using common lab glass and lab equipment. First, dichloromethane is refluxed with calcium hydride to remove water. Then, dichloromethane is distilled to separate it from the byproducts of the reflux reaction. This procedure can be implemented in 1 day. ### Introduction In many instances i...

  9. 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.

  10. Study on the Influence of Anti-oxidants on Oxidation Stability of the Calcium Sulfonate Complex Grease by Using Pressure Differential Scanning Calorimetry%抗氧剂对复合磺酸钙基润滑脂氧化安定性的高压差示扫描量热法研究

    Institute of Scientific and Technical Information of China (English)

    谢龙; 程型国; 周圆

    2012-01-01

    利用高压差示扫描量热法(PDSC)研究了典型抗氧剂T501(2,6-二叔丁基对甲基苯酚)、L135(高分子量液体酚)、L57(辛基/戊基二苯胺)和T531(N-苯基-α萘胺)对复合磺酸钙基润滑脂氧化安定性的影响,考察了抗氧剂浓度对抗氧化效果的影响.结果表明,PDSC是一种快速简便评价润滑脂氧化安定性的方法,适用于抗氧剂的筛选.与传统的旋转氧弹氧化法相比较而言,PDSC的评价结果更科学,更具有规律性.另外,根据阿仑尼乌斯公式计算了润滑脂氧化反应的表观活化能.%Pressure differential scanning calorimetry(PDSC) was used to evaluate the effect of several anti-oxidants such as T501 (2, 6-ditert-butyl-4-methyl phenol). L135 (high molecular weight liquid phenol), L57 (octyl/amyl diphenylamine) and T531 ( N-phenyl-α-naphthylamine) on the oxidation stability of calcium sulfonate complex grease. The results showed that PDSC was a simple and rapid method for testing the oxidation of grease, and suitable for screening anti-oxidants. Compared with traditional oxygen bomb oxidation method, the evaluation result of PDSC provided a better scientific foundation and better regularity. In addition, the active energies of grease oxidation were calculated by using Arrhenius-equation.

  11. A histochemical and X-ray microanalysis study of calcium changes in insect flight muscle degeneration in Solenopsis, the queen fire ant

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.G.; Davis, W.L.; Vinson, S.B.

    1982-04-01

    Potassium pyroantimonate histochemistry, coupled with ethyleneglycoltetraacetic acid (EGTA)-chelation and X-ray microprobe analysis, was employed to localize intracellular calcium binding sites in the normal and degenerating flight musculature in queens of Solenopsis, the fire ant. In normal animals, calcium distribution was light to moderate within myofibrils and mitochondria. In the early contracture stages of the insemination-induced degeneration, both myofilament and mitochondrial calcium loading was markedly increased. In the terminal stages of myofibril breakdown, only Z-lines (isolated or in clusters) with an associated filamentous residue persisted. These complexes were also intensely calcium positive. This study further documents the presence of increased sarcoplasmic calcium during muscle necrosis. Surface membrane defects, mitochondrial calcium overload, and calcium-activated proteases may all be involved in this ''normal'' breakdown process.

  12. A histochemical and X-ray microanalysis study of calcium changes in insect flight muscle degeneration in Solenopsis, the queen fire ant

    International Nuclear Information System (INIS)

    Potassium pyroantimonate histochemistry, coupled with ethyleneglycoltetraacetic acid (EGTA)-chelation and X-ray microprobe analysis, was employed to localize intracellular calcium binding sites in the normal and degenerating flight musculature in queens of Solenopsis, the fire ant. In normal animals, calcium distribution was light to moderate within myofibrils and mitochondria. In the early contracture stages of the insemination-induced degeneration, both myofilament and mitochondrial calcium loading was markedly increased. In the terminal stages of myofibril breakdown, only Z-lines (isolated or in clusters) with an associated filamentous residue persisted. These complexes were also intensely calcium positive. This study further documents the presence of increased sarcoplasmic calcium during muscle necrosis. Surface membrane defects, mitochondrial calcium overload, and calcium-activated proteases may all be involved in this ''normal'' breakdown process

  13. Calcium Fructoborate for Bone and Cardiovascular Health.

    Science.gov (United States)

    Mogoşanu, George Dan; Biţă, Andrei; Bejenaru, Ludovic Everard; Bejenaru, Cornelia; Croitoru, Octavian; Rău, Gabriela; Rogoveanu, Otilia-Constantina; Florescu, Dan Nicolae; Neamţu, Johny; Scorei, Iulia Daria; Scorei, Romulus Ion

    2016-08-01

    Calcium fructoborate (CF), a natural sugar-borate ester found in fresh fruits and vegetables, is a source of soluble boron. CF contains three forms of borate (diester, monoester, and boric acid) and all are biologically active, both at the intracellular (as free boric acid) and extracellular level (as fructose-borate diester and monoester). At the cellular and molecular level, CF is superior to the boric acid/borate, exhibiting a complex "protective" effect against inflammatory response. CF is commercially available in the USA as a "nature-identical" complex, an active compound for dietary supplements. It provides effective and safe support against the discomfort and lack of flexibility associated with osteoarticular conditions (arthritis and joint degeneration), and improves Western Ontario and McMaster Universities Osteoarthritis (WOMAC) and McGill indexes. In addition, orally administered CF is effective in ameliorating symptoms of physiological response to stress, including inflammation of the mucous membranes, discomfort associated with osteoarthritis disorders, and bone loss, and also for supporting cardiovascular health. Clinical studies have exhibited the ability of CF to significantly modulate molecular markers associated with inflammatory mechanisms, mainly on the elevated serum levels of C-reactive protein (CRP). PMID:26686846

  14. Rapid screening assay for calcium bioavailability studies

    International Nuclear Information System (INIS)

    Calcium bioavailability has been studied by numerous techniques. The authors report here the use of the gamma emitting isotope of calcium (47Ca) in a whole body retention assay system. In this system, calcium sources are administered by oral gavage and subsequent counts are determined and corrected for isotopic decay. Unlike iron and zinc retention curves, which exhibit a 2-3 day equilibration period, calcium reaches equilibration after 24 hours. Autoradiographic analysis of the femurs indicate that the newly absorbed calcium is rapidly distributed to the skeletal system. Moreover, the isotope is distributed along the entire bone. Comparisons of calcium bioavailability were made using intrinsic/extrinsic labeled milk from two species i.e. rat and goat as well as CaCO3. In addition, extrinsic labeled cow milk was examined. In the rat, the extrinsic labeled calcium from milk was better absorbed than the intrinsic calcium. This was not the case in goat milk or the calcium carbonate which exhibited no significant differences. Chromatographic analysis of the labeled milk indicates a difference in distribution of the 47Ca. From these data, the authors recommend the use of this assay system in calcium bioavailability studies. The labeling studies and comparisons indicate caution should be used, however, in labeling techniques and species milk comparison

  15. [Calcium antagonism by papaverine in isolated rat gastric fundus strips in a model system].

    Science.gov (United States)

    Simon, L; Sallai, J; Szontagh, M; Simon-Talpas, G; Müller, A

    1984-04-01

    Examining isolated strips of gastric fundus tissue of rats the authors observed that papaverin up to 7.8 X 10(-8) to 6.25 X 10(-7) mol/l increased the intensity of convulsions induced by constant amounts of barium chloride (9.5 X 10(-4); with further increase of the concentration the intensity of convulsions gradually sank under the initial value. An increased proneness to cramping was also observed when the calcium content of the Tyrode solution was reduced. In this case the proneness to cramping was highest between 1 and 1.3 mmol/l calcium content. When the calcium content was 1 mmol/l, papaverin increased the proneness to cramping only to a smaller degree, in agreement with the effect measured when the calcium content of the organ bath was reduced below 1 mmol/l. In model experiments, calcium antagonized the potential difference-increasing effect of papaverin at the ether/NaCl (0.1 mol/l) phase boundary. From this the authors infer an interaction (complex formation) between papaverin and calcium at the phase boundary, which is independent of the biological medium. Their findings and the papaverin -calcium antagonism first observed by Benigni [2] can be interpreted in this way. PMID:6739529

  16. Cytosolic organelles shape calcium signals and exo-endocytotic responses of chromaffin cells.

    Science.gov (United States)

    García, Antonio G; Padín, Fernando; Fernández-Morales, José C; Maroto, Marcos; García-Sancho, Javier

    2012-01-01

    The concept of stimulus-secretion coupling was born from experiments performed in chromaffin cells 50 years ago. Stimulation of these cells with acetylcholine enhances calcium (Ca(2+)) entry and this generates a transient elevation of the cytosolic Ca(2+) concentration ([Ca(2+)](c)) that triggers the exocytotic release of catecholamines. The control of the [Ca(2+)](c) signal is complex and depends on various classes of plasmalemmal calcium channels, cytosolic calcium buffers, the uptake and release of Ca(2+) from cytoplasmic organelles, such as the endoplasmic reticulum, mitochondria, chromaffin vesicles and the nucleus, and Ca(2+) extrusion mechanisms, such as the plasma membrane Ca(2+)-stimulated ATPase, and the Na(+)/Ca(2+) exchanger. Computation of the rates of Ca(2+) fluxes between the different cell compartments support the proposal that the chromaffin cell has developed functional calcium tetrads formed by calcium channels, cytosolic calcium buffers, the endoplasmic reticulum, and mitochondria nearby the exocytotic plasmalemmal sites. These tetrads shape the Ca(2+) transients occurring during cell activation to regulate early and late steps of exocytosis, and the ensuing endocytotic responses. The different patterns of catecholamine secretion in response to stress may thus depend on such local [Ca(2+)](c) transients occurring at different cell compartments, and generated by redistribution and release of Ca(2+) by cytoplasmic organelles. In this manner, the calcium tetrads serve to couple the variable energy demands due to exo-endocytotic activities with energy production and protein synthesis. PMID:22209033

  17. Ca2+ signals induced from calcium stores in pancreatic islet β cells

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In single rat pancreatic β cells,using fura-2 microfluorometry to measure [Ca2+]i response upon different stimuli,the ways of calcium regulation have been studied.When the extracellular calcium concentration was 2.5 mmol/L,either 60 mmol/L KCl,20 mmol/L D-glucose or 0.1 mmol/L tolbutamide induced increase in [Ca2+]i.Such increase in [Ca2+]i was absent when the same stimuli were applied under zero extracellular calcium.These results indicate that the increase of [Ca2+]i is induced by the activation of voltage-dependent calcium channels in β cells.The manifold forms of [Ca2+]i change induced by glucose imply that the effects of glucose are complex.5 mmol/L caffeine or 5 mmol/L MCh increase the [Ca2+]i ,which is independent of the external calcium,suggesting that [Ca2+]i can be regulated by Ca2+ release from not only the IP3-sensitive but also the ryanodine sensitive calcium stores in β cells.The latency of Ca responses for IP3 pathway (5 s) is faster than that for ryanodine pathway (30 s).It is concluded that there are multiple calcium stores in rat pancreatic β cells.

  18. Calcium sensitizers: What have we learned over the last 25 years?

    Science.gov (United States)

    Pollesello, P; Papp, Z; Papp, J Gy

    2016-01-15

    The use of inotropes for correcting hemodynamic dysfunction in patients with congestive heart failure has been described over many decades. Drugs such as cardiac glycosides, cathecolamines, phosphodiestherase inhibitors, and calcium sensitizers have been in turn proposed. However, the number of new chemical entities in this therapeutic field has been surprisingly low, and the current selection of drugs is limited. One of the paradigm shifts in the discovery for new inotropes was to focus on 'calcium sensitizers' instead of 'calcium mobilizers'. This was designed to lead to the development of safer inotropes, devoid of the complications that arise due to increased intracellular calcium levels. However, only three such calcium sensitizers have been fully developed over the latest 30 years. Moreover, two of these, levosimendan and pimobendan, have multiple molecular targets and other pharmacologic effects in addition to inotropy, such as peripheral vasodilation. More recently, omecamtiv mecarbil was described, which is believed to have a pure inotropy action that is devoid of pleiotropic effects. When the clinical data of these three calcium sensitizers are compared, it appears that the less pure inotropes have the cutting edge over the purer inotrope, due to additional effects during the treatment of a complex syndrome such as acute congested heart failure. This review aims to answer the question whether calcium sensitization per se is a sufficient strategy for bringing required clinical benefits to patients with heart failure. This review is dedicated to the memory of Heimo Haikala, a true and passionate innovator in this challenging field. PMID:26580334

  19. STIM1 is a Calcium Sensor Specialized for Digital Signaling

    OpenAIRE

    Bird, Gary S.; Hwang, Sung-Yong; Smyth, Jeremy T.; Fukushima, Miwako; Boyles, Rebecca R.; Putney, James W.

    2009-01-01

    When cells are activated by calcium-mobilizing agonists at low, physiological concentrations, the resulting calcium signals generally take the form of repetitive regenerative discharges of stored calcium, termed calcium oscillations [1]. These intracellular calcium oscillations have long fascinated biologists as representing a mode of digitized intracellular signaling. Recent work has highlighted the role of calcium influx as an essential component of calcium oscillations [2]. This influx occ...

  20. Differential regulation of calcium signalling pathways by components of Piper methysticum (‘Awa)

    Science.gov (United States)

    Shimoda, L.M.N; Showman, A.; Baker, J.D.; Lange, I.; Koomoa, D.L.; Stokes, A.J.; Borris, R.P.; Turner, H.

    2015-01-01

    Kava is a soporific, anxiolytic and relaxant in widespread ritual and recreational use throughout the Pacific. Traditional uses of kava by indigenous Pacific Island peoples reflect a complex pharmacopeia, centered on GABA-ergic effects of the well-characterized kavalactones. However, peripheral effects of kava suggest active components other than the CNS-targeted kavalactones. We have previously shown that immunocytes exhibit calcium mobilization in response to traditionally-prepared kava extracts, and that the kavalactones do not induce these calcium responses. Here, we characterize the complex calcium-mobilizing activity of traditionally-prepared and partially HPLC-purified kava extracts, noting induction of both calcium entry and store release pathways. Kava components activate intracellular store depletion of thapsigargin-sensitive and –insensitive stores that are coupled to the calcium release activated (CRAC) current, and cause calcium entry through non-store-operated pathways. Together with the pepper-like potency reported by kava users, these studies lead us to hypothesize that kava extracts contain one or more ligands for the transient receptor potential (TRP) family of ion channels. Indeed, TRP-like conductances are observed in kava-treated cells under patch clamp. Thus TRP-mediated cellular effects may be responsible for some of the reported pharmacology of kava. PMID:25640812

  1. Fortification of all-purpose wheat-flour tortillas with calcium lactate, calcium carbonate, or calcium citrate is acceptable.

    Science.gov (United States)

    Romanchik-Cerpovicz, Joelle E; McKemie, Rebecca J

    2007-03-01

    Fortification helps provide adequate nutrients for individuals not meeting daily needs. Foods may be fortified with calcium to assist individuals with lactose intolerance and others preferring not to consume traditional forms of dairy. This study examined the quality of all-purpose wheat-flour tortillas fortified with calcium lactate, calcium carbonate, or calcium citrate. These tortillas were compared to similarly prepared nonfortified flour tortillas (control) and commercial nonfortified flour tortillas. Calcium-fortified tortillas contained 114 mg elemental calcium per standard serving (48 g tortilla), an 8.6-fold increase compared to nonfortified tortillas. Moisture contents and rollabilities of all tortillas were similar. Consumers (N=87) evaluated each tortilla in duplicate using a hedonic scale and reported liking the appearance, texture, flavor, aftertaste, and overall acceptability of all tortillas. However, the appearance of control tortillas was preferred over commercial tortillas (Ptortillas or those fortified with calcium carbonate was preferred over the control (Ptortillas, suggesting that appearance and aftertaste may not influence willingness to purchase. Overall, this study shows that fortification of flour tortillas with various forms of calcium is a feasible alternative calcium source. PMID:17324671

  2. Biphasic calcium phosphate in periapical surgery

    OpenAIRE

    Suneelkumar, Chinni; Datta, Krithika; Manali R Srinivasan; Kumar, Sampath T

    2008-01-01

    Calcium phosphate ceramics like hydroxyapatite and β -tricalcium phosphate (β -TCP) possess mineral composition that closely resembles that of the bone. They can be good bone substitutes due to their excellent biocompatibility. Biphasic calcium phosphate is a bone substitute which is a mixture of hydroxyapatite and β -tricalcium phosphate in fixed ratios. Studies have demonstrated the osteoconductive potential of this composition. This paper highlights the clinical use of biphasic calcium pho...

  3. Gravity, Calcium, And Bone: Update, 1989

    Science.gov (United States)

    Arnaud, Sara B.; Morey-Holton, Emily

    1992-01-01

    Report reviews short-term flight and ground-based experiments on effects of 1 g and 0 g on skeletal adaptation, calcium metabolism, and growth processes. Results indicate two principal components of calcium metabolism-calcium endocrine system and bone - respond within days to changes in orientation of body in gravitation and to weightlessness. Effects of spaceflight or bed rest on biomechanics of bones more severe than on total body bone mass.

  4. Gravity, calcium, and bone - Update, 1989

    Science.gov (United States)

    Arnaud, Sara B.; Morey-Holton, Emily

    1990-01-01

    Recent results obtained on skeletal adaptation, calcium metabolism, and bone browth during short-term flights and ground simulated-microgravity experiments are presented. Results demonstrate that two principal components of calcium metabolism respond within days to changes in body position and to weightlessness: the calcium endocrine system and bone characteristics. Furthermore, results of recent studies imply that bone biomechanics are more severely affected by spaceflight exposures than is the bone mass.

  5. 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...... FHH, while in homozygous patients as well as in compound heterozygous or dominant negative heterozygous patients, it may result in neonatal severe hyperparathyroidism (NSHPT). Parathyroid surgery is not indicated in FHH and does not lower plasma calcium unless total parathyroidectomy is performed, in...

  6. Overbased Calcium sulfonate Detergent Technology Overview

    Institute of Scientific and Technical Information of China (English)

    MA Qing-gao; MUIR Ronald J.

    2009-01-01

    Overbased calcium sulfonate is used widely as detergent in automotive and marine lubricants, as well as various industrial oil applications. In this paper, the process to produce overbased calcium sulfonate is overviewed. The sulfonate structure and molecular weight and its molecular weight distribution, the enclosed calcium carbonate nanoparticle size and crystalline structure, properties of the carrier oil, all influence its properties, such as stability, viscosity, and detergency of the system.

  7. Calcium hydroxide isotope effect in calcium isotope enrichment by ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Jepson, B.E.; Shockey, G.C.

    1984-01-01

    The enrichment of calcium isotopes has been observed in ion-exchange chromatography with an aqueous phase of calcium hydroxide and a solid phase of sulfonic acid resin. The band front was exceedingly sharp as a result of the acid-base reaction occuring at the front of the band. Single-stage separation coefficients were found to be epsilon(/sup 44/Ca//sup 40/Ca) = 11 x 10 /sup -4/ and epsilon(/sup 48/Ca//sup 40/Ca) = 18 x 10/sup -4/. The maximum column separation factors achieved were 1.05 for calcium-44 and 1.09 for calcium-48 with the heavy isotopes enriching in the fluid phase. The calcium isotope effect between fully hydrated aqueous calcium ions and undissociated aqueous calcium hydroxide was estimated. For the calcium-44/40 isotope pair the separation coefficient was 13 x 10/sup -4/. 20 references, 2 figures.

  8. Calcium carboorthovanadate - a new compound with the apa

    International Nuclear Information System (INIS)

    Data on calcium carboorthovanadate, Ca10(VO4)6CO3, a new compound with an appatite structure based on calcium orthovanadate, are reported. The synthesis has been conducted in a stoichiometric mixture of finely ground calcium carbonate and calcium orthovanadate. It is found that calcium carboorthovanadate belongs to the hexagonal syngony and has an apatite structure. An analysis of the infrared spectra of initial compounds and calcium carboorthovanadate confirmed the presence of carbonate (CO3)2- and orthovanadate (VO4)3 groupings in the latter. On heating in air, beginning with 450 deg C calcium carboorthovanadate decomposes at a slow rate into calcium oxide, calcium orthovanadate, and carbon dioxide

  9. Characteristics of the interaction of calcium with casein submicelles as determined by analytical affinity chromatography

    International Nuclear Information System (INIS)

    Interaction of calcium with casein submicelles was investigated in CaCl2 and calcium phosphate buffers and with synthetic milk salt solutions using the technique of analytical affinity chromatography. Micelles that had been prepared by size exclusion chromatography with glycerolpropyl controlled-pore glass from fresh raw skim milk that had never been cooled, were dialyzed at room temperature against calcium-free imidazole buffer, pH 6.7. Resulting submicelles were covalently immobilized on succinamidopropyl controlled-pore glass (300-nm pore size). Using 45Ca to monitor the elution retardation, the affinity of free Ca2+ and calcium salt species was determined at temperatures of 20 to 40 degrees C and pH 6.0 to 7.5. Increasing the pH in this range or increasing the temperature strengthened the binding of calcium to submicelles, similar to previous observations with individual caseins. However, the enthalpy change obtained from the temperature dependence was considerably greater than that reported for alpha s1- and beta-caseins. Furthermore, the elution profiles for 45Ca in milk salt solutions were decidedly different from those in CaCl2 or calcium phosphate buffers and the affinities were also greater. For example, at pH 6.7 and 30 degrees C the average dissociation constant for the submicelle-calcium complex is 0.074 mM for CaCl2 and calcium phosphate buffers, vs 0.016 mM for the milk salt solution. The asymmetric frontal boundaries and higher average affinities observed with milk salts may be due to binding of calcium salts with greater affinity in addition to the binding of free Ca2+ in these solutions

  10. Calcium supplements: do they help or harm?

    Science.gov (United States)

    Manson, Joann E; Bassuk, Shari S

    2014-01-01

    Current recommendations for calcium intake call for 1,000 mg per day for women ages 19-50 and 1,200 mg per day for women over age 50 to ensure bone health. Given recent concerns that calcium supplements may raise risk for cardiovascular disease and kidney stones, women should aim to meet this recommendation primarily by eating a calcium-rich diet and taking calcium supplements only if needed to reach the RDA goal (often only approximately 500 mg per day in supplements is required). PMID:23880796

  11. Peroxisome is a reservoir of intracellular calcium.

    Science.gov (United States)

    Raychaudhury, Bikramjit; Gupta, Shreedhara; Banerjee, Shouvik; Datta, Salil C

    2006-07-01

    We have examined fura 2-loaded purified peroxisomes under confocal microscope to prove that this mammalian organelle is a store of intracellular calcium pool. Presence of calcium channel and vanadate sensitive Ca(2+)-ATPase in the purified peroxisomal membrane has been demonstrated. We have further observed that machineries to maintain calcium pool in this mammalian organelle are impaired during infection caused by Leishmania donovani. Results reveal that peroxisomes have a merit to play a significant role in the metabolism of intracellular calcium. PMID:16713100

  12. Calcium wave of Brain Astrocytes

    Science.gov (United States)

    Cornell Bell, A. H.

    1997-03-01

    Time lapse confocal scanning laser microscopy was used to study hippocampal astrocyte cultures loaded with a calcium indicator, Fluo3-AM (4 uM). kThe neurotransmitter kainate (100uM) overwhelms the Na+-buffering capacity of astrocytes within 100 sec resulting in reversal of the Na+/Ca2+ exchanger. This results in a subcellular site where Ca2+ entering the cytoplasm contributes to a long-distance Ca2+ wave which travels at 20 um/sec without decrement. Image analysis has shown calcium waves not only at a high Kainate dose, but also at a low Kainate dose, e.g. 10uM. These are, however, shortlived and burried in an extremely noisy background and only detectable by analyzing the calcium waves images for spatio-temporal coherence. As the kainate dose increases, more large scale coherent structures with visible geometric features (spiral waves and target waves) can be observed. Multiple spiral waves are produced when the Kainate dose increases to 100 uM. These waves travel at a constant velocity across entire microscope fields for long time periods (>30 mins). Na+ channels have no effect on the Kainate wave. Voltage-gated Ca2+ channels are not involved and Ca2+ enters through reversal of the exchanger. Ca2+ release from stores does not contribute to the kainate wave. Removal of Na+ or Ca2+ from outside and the specific Na+/Ca2+ exchange inhibitor benzamil (10 uM) inhibit the kainate wave. A functional antibody to alpha6-Integrin which is localized to membrane regions between cells inhibits the spread of the kainate wave in a dose and time-dependent manner. Fluorescence Recovery after Photobleach (FRAP) techniques indicate that gap junctions remain open between cells. This would imply that Ca2+ or IP3 need not pass through the gap junction, but reversal of the exchanger would propel the Ca2+ wave at the cell surface.

  13. Calcium and magnesium silicate hydrates

    International Nuclear Information System (INIS)

    Deep geological disposals are planed to discard long-lived intermediate-level and high-level radioactive wastes. Clay-based geological barriers are expected to limit the ingress of groundwater and to reduce the mobility of radioelements. In the interaction zone between the cement and the clay based material alteration can occur. Magnesium silicate hydrates (M-S-H) have been observed due to the reaction of magnesium sulfate containing groundwater with cements or in the interaction zone between low-pH type cement and clays. M-S-H samples synthesized in the laboratory showed that M-S-H has a variable composition within 0.7 ≤ Mg/Si ≤ 1.5. TEM/EDS analyses show an homogeneous gel with no defined structure. IR and 29Si NMR data reveal a higher polymerization degree of the silica network in M-S-H compared to calcium silicate hydrates (C-S-H). The presence of mainly Q3 silicate tetrahedrons in M-S-H indicates a sheet like or a triple-chain silica structure while C-S-H is characterised by single chain-structure. The clear difference in the silica structure and the larger ionic radius of Ca2+ (1.1 Angstrom) compared to Mg2+ (0.8 Angstrom) make the formation of an extended solid solution between M-S-H and C-S-H gel improbable. In fact, the analyses of synthetic samples containing both magnesium and calcium in various ratios indicate the formation of separate M-S-H and C-S-H gels with no or very little uptake of magnesium in CS-H or calcium in M-S-H

  14. Selective extraction of calcium on tri-n-butyl phosphate plasticized selective extraction of calcium on tri-n-butyl phosphate plasticized polyurethane foam for its spectrophotometric determination in glass and ceramics.

    Science.gov (United States)

    Mondal, Jayanta K; Kundu, Dipali

    2005-12-01

    The present paper describes the application of a solid phase extraction system in order to separate traces of calcium from glass and ceramics for its spectrophotometric determination. The method is based on the extraction of calcium from sodium hydroxide solution by tri-n-butyl phosphate (TBP) loaded polyurethane foam (PUF), followed by its elution in hydrochloric acid. The spectrophotometric measurement of the absorbance of calcium complex with calconcarboxylic acid (2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3-naphthoic acid) takes place at pH 12. The following parameters were studied: effects of sodium hydroxide concentration and temperature on the extraction of calcium, time of equilibration for quantitative calcium extraction, effect of TBP concentration, effect of hydrochloric acid concentration for quantitative elution of calcium from PUF, effect of pH and concentration of calconcarboxylic acid for quantitative formation of the complex with calcium, effect of acetone on the stability of calcium-calconcarboxylic acid complex and influence of diverse ions on calcium sorption by TBP-loaded PUF. The results show that calcium traces can be separated onto TBP-loaded PUF from 0.25 mol L(-1) NaOH at 30 +/- 5 degrees C within 30 min. PUF was loaded with TBP in CCl4 (40% v/v). Elution of calcium was done in 1.0 mol l(-1) HCl. The calcium formed a complex with calconcarboxylic acid at pH 12 and absorbance was measured at 560 nm in acetone-water medium. Molar absorptivity was found to be 1.082 x 10(4) l mol(-1) cm(-1). The method obeys Beer's law from 0.10 to 5.0 microg ml(-1) Ca. The validity of the method was established by its successful application in NIST standard reference materials. The method proposed was applied to determine calcium in glass and ceramic materials. The results of the proposed method are comparable with the results of ICP-AES analysis and they are found to be in good agreement. PMID:16379392

  15. Calcium Absorption from Fortified Ice Cream Formulations Compared with Calcium Absorption from Milk

    OpenAIRE

    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

    2009-01-01

    Objective 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-fort...

  16. Association of Urinary Calcium Excretion with Serum Calcium and Vitamin D Levels

    OpenAIRE

    A Rathod; Bonny, O; Guessous, I; Suter, P M; Conen, D; Erne, P; Binet, I; Gabutti, L; Gallino, A; Muggli, F; Hayoz, D; Pechere-Bertschi, A; Paccaud, F.; Burnier, M.; Bochud, M

    2015-01-01

    BACKGROUND AND OBJECTIVES: Population-based data on urinary calcium excretion are scarce. The association of serum calcium and circulating levels of vitamin D [25(OH)D2 or D3] with urinary calcium excretion in men and women from a population-based study was explored. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: Multivariable linear regression was used to explore factors associated with square root-transformed 24-hour urinary calcium excretion (milligrams per 24 hours) taken as the dep...

  17. Drosophila mushroom body Kenyon cells generate spontaneous calcium transients mediated by PLTX-sensitive calcium channels.

    OpenAIRE

    Jiang, Shaojuan Amy; Campusano, Jorge M.; Su, Hailing; O'Dowd, Diane K.

    2005-01-01

    Spontaneous calcium oscillations in mushroom bodies of late stage pupal and adult Drosophila brains have been implicated in memory consolidation during olfactory associative learning. This study explores the cellular mechanisms regulating calcium dynamics in Kenyon cells, principal neurons in mushroom bodies. Fura-2 imaging shows that Kenyon cells cultured from late stage Drosophila pupae generate spontaneous calcium transients in a cell autonomous fashion, at a frequency similar to calcium o...

  18. The Electronic Structure of Calcium

    DEFF Research Database (Denmark)

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

    1981-01-01

    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.......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...

  19. Physicochemical investigation of calcium bromtechnetate

    International Nuclear Information System (INIS)

    Calcium hexabromotechnetate is extracted for the first time and its composition corresponding to the CaTcBr6 formula is determined. Using the thermal analysis method the anhydrous salt stability boundaries are found. The X-ray phase analysis has shown the compound to be isostructural with (NH4)2TcI6 and has a rhombic b.c.c. crystal lattice with the following parameters: a=10.39+-0.01, b=7.34+-0.01 and c=7.45+-0.001A. At 380-420 deg C CaTcBr6 decomposes to Tc, CaBr2 and Br

  20. Barium calcium hydroxyapatite solid solutions

    International Nuclear Information System (INIS)

    The replacement of calcium by barium in the hydroxyapatite structure by solid-state reaction at different temperatures and by precipitation from an aqueous system has been investigated by X-ray diffraction and i.r. absorption analyses. The products obtained by solid-state reaction at 1200 deg C are solid solutions over the range of barium concentration 60 to 100 atom %. The lattice dimensions and the i.r. frequencies of the solid solutions vary linearly with the atom % of barium. Only small amounts of barium can be incorporated in hydroxyapatite by precipitation from the aqueous system. (author)

  1. Calcium

    Science.gov (United States)

    ... for lunch; and beans, salsa, taco sauce, and cheese for dinner. Create mini-pizzas by topping whole-wheat English muffins or bagels with pizza sauce and low-fat mozzarella or soy cheese. Try whole-grain crackers with low-fat cheese ...

  2. Calcium

    Science.gov (United States)

    ... eliminates in urine, feces, and sweat. These include consumption of alcohol- and caffeine-containing beverages as well as intake ... and older 2,000 mg Pregnant and breastfeeding teens 3,000 mg Pregnant and breastfeeding adults 2, ...

  3. Long-Term Blocking of Calcium Channels in mdx Mice Results in Differential Effects on Heart and Skeletal Muscle

    DEFF Research Database (Denmark)

    Jørgensen, Louise Helskov; Blain, Alison; Greally, Elizabeth;

    2011-01-01

    The disease mechanisms underlying dystrophin-deficient muscular dystrophy are complex, involving not only muscle membrane fragility, but also dysregulated calcium homeostasis. Specifically, it has been proposed that calcium channels directly initiate a cascade of pathological events by allowing...... calcium ions to enter the cell. The objective of this study was to investigate the effect of chronically blocking calcium channels with the aminoglycoside antibiotic streptomycin from onset of disease in the mdx mouse model of Duchenne muscular dystrophy (DMD). Treatment in utero onwards delayed onset of...... older mice. However, streptomycin treatment did not show positive effects in diaphragm or heart muscle, and heart pathology was worsened. Thus, blocking calcium channels even before disease onset does not prevent dystrophy, making this an unlikely treatment for DMD. These findings highlight the...

  4. Purification and characterisation of a glutamic acid-containing peptide with calcium-binding capacity from whey protein hydrolysate.

    Science.gov (United States)

    Huang, Shun-Li; Zhao, Li-Na; Cai, Xixi; Wang, Shao-Yun; Huang, Yi-Fan; Hong, Jing; Rao, Ping-Fan

    2015-02-01

    The bioavailability of dietary ionised calcium is affected by intestinal basic environment. Calcium-binding peptides can form complexes with calcium to improve its absorption and bioavailability. The aim of this study was focused on isolation and characterisation of a calcium-binding peptide from whey protein hydrolysates. Whey protein was hydrolysed using Flavourzyme and Protamex with substrate to enzyme ratio of 25:1 (w/w) at 49 °C for 7 h. The calcium-binding peptide was isolated by DEAE anion-exchange chromatography, Sephadex G-25 gel filtration and reversed phase high-performance liquid chromatography (RP-HPLC). A purified peptide of molecular mass 204 Da with strong calcium binding ability was identified on chromatography/electrospray ionisation (LC/ESI) tandem mass spectrum to be Glu-Gly (EG) after analysis and alignment in database. The calcium binding capacity of EG reached 67·81 μg/mg, and the amount increased by 95% compared with whey protein hydrolysate complex. The UV and infrared spectrometer analysis demonstrated that the principal sites of calcium-binding corresponded to the carboxyl groups and carbonyl groups of glutamic acid. In addition, the amino group and peptide amino are also the related groups in the interaction between EG and calcium ion. Meanwhile, the sequestered calcium percentage experiment has proved that EG-Ca is significantly more stable than CaCl2 in human gastrointestinal tract in vitro. The findings suggest that the purified dipeptide has the potential to be used as ion-binding ingredient in dietary supplements. PMID:25592629

  5. Calcium and Vitamin D: Important at Every Age

    Science.gov (United States)

    ... supported by your browser. Home Bone Basics Nutrition Calcium and Vitamin D: Important at Every Age Publication ... Osteoporosis Program For Your Information The Role of Calcium Calcium is needed for our heart, muscles, and ...

  6. Clinical validation of dialysable calcium in relation to other methods of serum calcium measurement.

    OpenAIRE

    Prince, R. L.; Langton, S R

    1985-01-01

    Dialysable calcium (CaD) values were measured by a simple technique not interfered with by protein bound calcium and validation attempted by comparison with concentrations of ionised calcium (CaI) and clinical categorisation. CaD values were also compared with total calcium (CaT) and albumin adjusted calcium (CaA) concentrations. The normal ranges for CaD, CaT, CaA, and CaI were calculated from the results in healthy blood donors. In 50 normal subjects CaD was more highly correlated with CaI ...

  7. An Intracellular Calcium Oscillations Model Including Mitochondrial Calcium Cycling

    Institute of Scientific and Technical Information of China (English)

    SHI Xiao-Min; LIU Zeng-Rong

    2005-01-01

    @@ Calcium is a ubiquitous second messenger. Mitochondria contributes significantly to intracellular Ca2+ dynamics.The experiment of Kaftan et al. [J. Biol. Chem. 275(2000) 25465] demonstrated that inhibiting mitochondrial Ca2+ uptake can reduce the frequency of cytosolic Ca2+ concentration oscillations of gonadotropes. By considering the mitochondrial Ca2+ cycling we develop a three-variable model of intracellular Ca2+ oscillations based on the models of Atri et al. [Biophys. J. 65 (1993) 1727] and Falcke et al. [Biophys. J. 77 (1999) 37]. The model reproduces the fact that mitochondrial Ca2+ cycling increases the frequency of cytosolic Ca2+ oscillations, which accords with Kaftan's results. Moreover the model predicts that when the mitochondria overload with Ca2+, the cytosolic Ca2+ oscillations vanish, which may trigger apoptosis.

  8. Bone Up on the Need for Calcium.

    Science.gov (United States)

    Mann, Peggy

    1987-01-01

    Most grade-schoolers drink milk at each meal, but teens, especially girls, often switch to carbonated soda at mealtime just as they should be building up their bone bank of calcium. Why calcium is important and how to get enough of it are covered. (MT)

  9. 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... phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This...

  10. 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.

  11. Calcium Free Asbestos for Fuel Cells

    Science.gov (United States)

    Snitzer, B. A.

    1983-01-01

    Organic-acid salt removes unwanted calcium without weakening asbestos. Asbestos mixed with disodium ethylene diamine tetraacetic acid (disodium EDTA) in water and agitated for 2 hours. After disodium EDTA solution is drained away, asbestos contains only 0.02 to 0.1 percent calcium. Fiber structure of asbestos unaffected.

  12. Stochastic models of intracellular calcium signals

    International Nuclear Information System (INIS)

    Cellular signaling operates in a noisy environment shaped by low molecular concentrations and cellular heterogeneity. For calcium release through intracellular channels–one of the most important cellular signaling mechanisms–feedback by liberated calcium endows fluctuations with critical functions in signal generation and formation. In this review it is first described, under which general conditions the environment makes stochasticity relevant, and which conditions allow approximating or deterministic equations. This analysis provides a framework, in which one can deduce an efficient hybrid description combining stochastic and deterministic evolution laws. Within the hybrid approach, Markov chains model gating of channels, while the concentrations of calcium and calcium binding molecules (buffers) are described by reaction–diffusion equations. The article further focuses on the spatial representation of subcellular calcium domains related to intracellular calcium channels. It presents analysis for single channels and clusters of channels and reviews the effects of buffers on the calcium release. For clustered channels, we discuss the application and validity of coarse-graining as well as approaches based on continuous gating variables (Fokker–Planck and chemical Langevin equations). Comparison with recent experiments substantiates the stochastic and spatial approach, identifies minimal requirements for a realistic modeling, and facilitates an understanding of collective channel behavior. At the end of the review, implications of stochastic and local modeling for the generation and properties of cell-wide release and the integration of calcium dynamics into cellular signaling models are discussed

  13. 21 CFR 172.410 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Anticaking Agents § 172.410 Calcium...

  14. Engineering calcium oxalate crystal formation in Arabidopsis

    Science.gov (United States)

    Many plants accumulate crystals of calcium oxalate. Just how these crystals form remains unknown. To gain insight into the mechanisms regulating calcium oxalate crystal formation, a crystal engineering approach was initiated utilizing the non-crystal accumulating plant, Arabidopsis. The success of t...

  15. Stochastic models of intracellular calcium signals

    Energy Technology Data Exchange (ETDEWEB)

    Rüdiger, Sten, E-mail: sten.ruediger@physik.hu-berlin.de

    2014-01-10

    Cellular signaling operates in a noisy environment shaped by low molecular concentrations and cellular heterogeneity. For calcium release through intracellular channels–one of the most important cellular signaling mechanisms–feedback by liberated calcium endows fluctuations with critical functions in signal generation and formation. In this review it is first described, under which general conditions the environment makes stochasticity relevant, and which conditions allow approximating or deterministic equations. This analysis provides a framework, in which one can deduce an efficient hybrid description combining stochastic and deterministic evolution laws. Within the hybrid approach, Markov chains model gating of channels, while the concentrations of calcium and calcium binding molecules (buffers) are described by reaction–diffusion equations. The article further focuses on the spatial representation of subcellular calcium domains related to intracellular calcium channels. It presents analysis for single channels and clusters of channels and reviews the effects of buffers on the calcium release. For clustered channels, we discuss the application and validity of coarse-graining as well as approaches based on continuous gating variables (Fokker–Planck and chemical Langevin equations). Comparison with recent experiments substantiates the stochastic and spatial approach, identifies minimal requirements for a realistic modeling, and facilitates an understanding of collective channel behavior. At the end of the review, implications of stochastic and local modeling for the generation and properties of cell-wide release and the integration of calcium dynamics into cellular signaling models are discussed.

  16. Particularities of thermal expansion of calcium vanadates

    International Nuclear Information System (INIS)

    Temperature dependence of unit cell parameters of calcium vanadates Ca(VO3)2, Ca2V2O7 and Ca3(VO4)2 is studied. It is shown that lattice parameters of meta- and pyrovanadates change monotonously. Lattice parameters of calcium orthovanadate change sharply and unmonotonously at 400-500 deg C

  17. 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.

  18. 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...

  19. The calcium-signaling toolkit: Updates needed.

    Science.gov (United States)

    Dubois, Charlotte; Prevarskaya, Natalia; Vanden Abeele, Fabien

    2016-06-01

    Here, we review the role of Ca(2+) in apoptosis, namely that ER Ca(2+) depletion or a sustained elevation of cytosolic or mitochondrial Ca(2+) concentration are sufficient to trigger apoptosis. These concepts have emerged by the use of ER stressor agents that decrease the ER Ca(2+) pool by inhibiting SERCA pumps. However, aside from their well-known actions on Ca(2+) homeostasis disruption leading to apoptosis, new evidence show that some ER Ca(2+) modulators have significant implications in other Ca(2+)-mediated or Ca(2+)-independent pathways determining cell fate suggesting a more complex regulation of apoptosis by intracellular Ca(2+). Here, we discuss the crucial interplay between Ca(2+) mediated apoptosis, the Unfold Protein Response and autophagy determining cell fate, and the molecular compounds that have been used to depict these pathways. This review of the literature clearly shows the need for new inhibitors that do not interfere concomitantly with autophagy and Ca(2+) signaling. 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. PMID:26658643

  20. Nano-porous calcium phosphate balls.

    Science.gov (United States)

    Kovach, Ildyko; Kosmella, Sabine; Prietzel, Claudia; Bagdahn, Christian; Koetz, Joachim

    2015-08-01

    By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. PMID:26052107

  1. Modularized study of human calcium signalling pathway

    Indian Academy of Sciences (India)

    Losiana Nayak; Rajat K De

    2007-08-01

    Signalling pathways are complex biochemical networks responsible for reg ulation of numerous cellular functions. These networks function by serial and successive interactions among a large number of vital biomolecules and chemical compounds. For deciphering and analysing the underlying mechanism of such networks, a modularized study is quite helpful. Here we propose an algorithm for modularization of calcium signalling pathway of H. sapiens. The idea that ``a node whose function is dependant on maximum number of other nodes tends to be the center of a sub network” is used to divide a large signalling network into smaller sub networks. Inclusion of node(s) into sub networks(s) is dependant on the outdegree of the node(s). Here outdegree of a node refers to the number of re lations of the considered node lying outside the constructed sub network. Node(s) having more than c relations lying outside the expanding subnetwork have to be excluded from it. Here is a specified variable based on user preference, which is finally fixed during adjustments of created subnetworks, so that certain biological significance can be conferred on them.

  2. Synthesis of hollow spherical calcium phosphate nanoparticles using polymeric nanotemplates

    International Nuclear Information System (INIS)

    Poly(methylmethacrylate)-block-poly(methacrylic acid) (PMMA-b-PMAA) copolymer was synthesized by an atom transfer radical polymerization (ATRP) technique. The block copolymer was employed as a template for the controlled precipitation of calcium phosphate from aqueous solution at different pH values. A Ca2+ ion selective electrode was used to study the interactions between Ca2+ ions and the polymer, which indicated a possible weak interaction between Ca2+ and un-ionized MAA segments at pH∼4.0 in addition to electrostatic interaction between Ca2+ and ionized MAA segments at higher pH. An interesting structure representing that of a superstructure consisting of hybrid nano-filaments was observed by the transmission electron microscope at pH∼4.0. The filaments originated from a core of similar size to primary polymer aggregates, suggesting that cooperative interactions at a local level between dissolving calcium phosphate clusters and disassembling polymer segments are responsible for the secondary growth process. A hollow spherical morphology was obtained at pH∼7.0 and 9.0. Such calcium phosphate/polymer monohybrids with complex morphologies are interesting and might be useful as novel drug delivery carriers, ceramics precursors, reinforcing fillers or biomedical implants

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

    Science.gov (United States)

    Garcia Ruiz, R. F.; Bissell, M. L.; 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.

    2016-06-01

    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-rich atomic nuclei.

  4. Calcium Carbide: A Unique Reagent for Organic Synthesis and Nanotechnology.

    Science.gov (United States)

    Rodygin, Konstantin S; Werner, Georg; Kucherov, Fedor A; Ananikov, Valentine P

    2016-04-01

    Acetylene, HC≡CH, is one of the primary building blocks in synthetic organic and industrial chemistry. Several highly valuable processes have been developed based on this simplest alkyne and the development of acetylene chemistry has had a paramount impact on chemical science over the last few decades. However, in spite of numerous useful possible reactions, the application of gaseous acetylene in everyday research practice is rather limited. Moreover, the practical implementation of high-pressure acetylene chemistry can be very challenging, owing to the risk of explosion and the requirement for complex equipment; special safety precautions need to be taken to store and handle acetylene under high pressure, which limit its routine use in a standard laboratory setup. Amazingly, recent studies have revealed that calcium carbide, CaC2 , can be used as an easy-to-handle and efficient source of acetylene for in situ chemical transformations. Thus, calcium carbide is a stable and inexpensive acetylene precursor that is available on the ton scale and it can be handled with standard laboratory equipment. The application of calcium carbide in organic synthesis will bring a new dimension to the powerful acetylene chemistry. PMID:26898248

  5. Molecular Structure and Target Recognition of Neuronal Calcium Sensor Proteins

    Directory of Open Access Journals (Sweden)

    James Ames

    2012-02-01

    Full Text Available Neuronal calcium sensor (NCS proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite distinct. Retinal recoverin and guanylate cyclase activating proteins (GCAPs both serve as calcium sensors in retinal rod cells, neuronal frequenin (NCS1 modulates synaptic activity and neuronal secretion, K+ channel interacting proteins (KChIPs regulate ion channels to control neuronal excitability, and DREAM (KChIP3 is a transcriptional repressor that regulates neuronal gene expression. Here we review the molecular structures of myristoylated forms of NCS1, recoverin, and GCAP1 that all look very different, suggesting that the sequestered myristoyl group helps to refold these highly homologous proteins into very different structures. The molecular structure of NCS target complexes have been solved for recoverin bound to rhodopsin kinase, NCS-1 bound to phosphatidylinositol 4-kinase, and KChIP1 bound to A-type K+ channels. We propose that N-terminal myristoylation is critical for shaping each NCS family member into a different structure, which upon Ca2+-induced extrusion of the myristoyl group exposes a unique set of previously masked residues that interact with a particular physiological target.

  6. 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-...

  7. Reversible adsorption of calcium ions by imprinted temperature sensitive gels

    Science.gov (United States)

    Alvarez-Lorenzo, Carmen; Guney, Orhan; Oya, Taro; Sakai, Yasuzo; Kobayashi, Masatoshi; Enoki, Takashi; Takeoka, Yukikazu; Ishibashi, Toru; Kuroda, Kenichi; Tanaka, Kazunori; Wang, Guoqiang; Grosberg, Alexander Yu.; Masamune, Satoru; Tanaka, Toyoichi

    2001-02-01

    With the aim of developing polymeric gels sensitive to external stimuli and able to reversibly adsorb and release divalent ions, copolymer gels of N-isopropylacrylamide (NIPA) and methacrylic (MAA) monomers were prepared. We chose calcium as a target divalent ion. Two MAAs form a complex with a calcium ion, and the NIPA component allows the polymers to swell and shrink reversibly in response to temperature. The adsorbing site develops an affinity to target ions when the adsorbing molecules come into proximity, but when they are separated, the affinity diminishes. To enhance the affinity to calcium, an imprinting technique was applied using Ca2+ and Pb2+ ions as templates in methylsulfoxide and dioxane media, respectively. The adsorption capacity of the imprinted gels was compared with that of the nonimprinted gels, and the effects of the templates, the solvents, and the amount of methacrylic monomers used in the synthesis and the medium temperature over the Ca2+ adsorption capacity of the gels from aqueous solutions were evaluated. The analysis of the adsorption revealed that (a) the adsorption can be described by the Langmuir isotherms; (b) there is an approximately linear relationship between saturation and methacrylic monomer concentration; (c) the affinity depends on the degree of gel swelling or shrinkage that can be switched on and off by temperature; (d) in the shrunken state, the affinity depends approximately linearly on the MAA concentration in the imprinted gels, whereas in the nonimprinted gels it is proportional to the square of MAA concentration; (e) the imprinted gels adsorb more than the nonimprinted gels when MAA concentration is less than that of permanent cross linkers. The success of imprinting of CaMAA2 and PbMAA2 complex is evidence for memory of such complex onto the weakly cross-linked gel.

  8. Calcium Forms,Subcelluar Distribution and Ultrastructure of Pulp Cells as Influenced by Calcium Deficiency in Apple (Malus pumila) Fruits

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-hui; ZHOU Wei

    2004-01-01

    Calcium in Red Fuji and Starkrimson apples during storage were fractionated by sequent extracting. Localization and distribution of calcium and influence of calcium nutrition on cell ultrastructure were observed by transmission electron microscopy combined with in situ precipitation of calcium with an improved method of potassium pyroantimonate technique. Results indicated that spraying calcium solution on surface of young fruits increased contents of calcium in all forms. During storage, contents of soluble calcium and pectic calcium declined and thosein calcium phosphate, calcium oxalate and calcium silicate increased. Calcium contents of Red Fuji in all forms were higher than those of Starkrimson, indicating that calcium accumulating capability of Red Fuji fruits preceded that of Starkrimson. Under transmission electron microscopy, calcium antimonite precipitates (CaAP) was mainly distributed in cell wall, tonoplast, nuclear membrane and nucleoplasm,much more CaAP deposited in vacuole. Calcium deficiency during storage leads to decrease of CaAP in locations mentioned above, disappearance of compartmentation, and entrance of CaAP to cytoplasm. Transformation from soluble calcium and pectic calcium to calcium phosphate,oxalate and damages of biomembranes structuraly and functionally resulted from calcium deficiency during storage were the crucial causation of physiological disorder.

  9. 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.

  10. Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

    Energy Technology Data Exchange (ETDEWEB)

    Sirvent, P., E-mail: pascal.sirvent@univ-bpclermont.fr [U1046, INSERM, Université Montpellier 1 and Université Montpellier 2, 34295 Montpellier (France); CHRU Montpellier, 34295 Montpellier (France); Clermont Université, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l' Exercice en conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171 Aubière cedex (France); Fabre, O.; Bordenave, S. [U1046, INSERM, Université Montpellier 1 and Université Montpellier 2, 34295 Montpellier (France); CHRU Montpellier, 34295 Montpellier (France); Hillaire-Buys, D. [CHRU Montpellier, 34295 Montpellier (France); Raynaud De Mauverger, E.; Lacampagne, A.; Mercier, J. [U1046, INSERM, Université Montpellier 1 and Université Montpellier 2, 34295 Montpellier (France); CHRU Montpellier, 34295 Montpellier (France)

    2012-03-01

    The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro. -- Highlights: ► The most common and problematic side effect of statins is myopathy. ► Patients treated with statins showed impairment of mitochondrial respiration. ► Statins-treated patients showed altered frequency and amplitude of calcium sparks.

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

    Science.gov (United States)

    Hillegonds, Darren J.; Vogel, John S.; Fitzgerald, Robert L.; Deftos, Leonard J.; Herold, David; Burton, Douglas W.

    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.

  12. Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

    Science.gov (United States)

    Leenheer, Jerry A.; Reddy, Michael M.

    2008-01-01

    Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

  13. Influence of calcium depletion on iron-binding properties of milk.

    Science.gov (United States)

    Mittal, V A; Ellis, A; Ye, A; Das, S; Singh, H

    2015-04-01

    We investigated the effects of calcium depletion on the binding of iron in milk. A weakly acidic cation-exchange resin was used to remove 3 different levels (18-22, 50-55, and 68-72%) of calcium from milk. Five levels of iron (5, 10, 15, 20, and 25 mM) were added to each of these calcium-depleted milks (CDM) and the resultant milks were analyzed for particle size, microstructure, and the distribution of protein and minerals between the colloidal and soluble phases. The depletion of calcium affected the distribution of protein and minerals in normal milk. Iron added to normal milk and low-CDM (~20% calcium depletion) bound mainly to the colloidal phase (material sedimented at 100,000 × g for 1 h at 20 °C), with little effect on the integrity of the casein micelles. Depletion of ~70% of the calcium from milk resulted in almost complete disintegration of the casein micelles, as indicated by all the protein remaining in the soluble phase upon ultracentrifugation. Addition of up to ~20 mM iron to high CDM resulted in the formation of small fibrous structures that remained in the soluble phase of milk. It appeared that the iron bound to soluble (nonsedimentable) caseins in high-CDM. We observed a decrease in the aqueous phosphorus content of all milks upon iron addition, irrespective of their calcium content. We considered the interaction between aqueous phosphorus and added iron to be responsible for the high iron-binding capacity of the proteins in milk. The soluble protein-iron complexes formed in high-CDM (~70% calcium depletion) could be used as an effective iron fortificant for a range of food products because of their good solubility characteristics. PMID:25648803

  14. A Single Nucleotide Polymorphism (rs4236480 in TRPV5 Calcium Channel Gene Is Associated with Stone Multiplicity in Calcium Nephrolithiasis Patients

    Directory of Open Access Journals (Sweden)

    Anas Khaleel

    2015-01-01

    Full Text Available Nephrolithiasis is characterized by calcification of stones in the kidneys from an unknown cause. Animal models demonstrated the functional roles of the transient receptor potential vanilloid member 5 (TRPV5 gene in calcium renal reabsorption and hypercalciuria. Therefore, TRPV5 was suggested to be involved in calcium homeostasis. However, whether genetic polymorphisms of TRPV5 are associated with kidney stone multiplicity or recurrence is unclear. In this study, 365 Taiwanese kidney-stone patients were recruited. Both biochemical data and DNA samples were collected. Genotyping was performed by a TaqMan allelic discrimination assay. We found that a TRPV5 polymorphism (rs4236480 was observed to be associated with stone multiplicity of calcium nephrolithiasis, as the risk of stone multiplicity was higher in patients with the TT+CT genotype than in patients with the CC genotype (p=0.0271. In summary, despite the complexity of nephrolithiasis and the potential association of numerous calcium homeostatic absorption/reabsorption factors, TRPV5 plays an important role in the pathogenesis of calcium nephrolithiasis.

  15. Calcium-mediated hydroboration of alkenes : "Trojan horse" or "true" catalysis?

    NARCIS (Netherlands)

    Harder, Sjoerd; Spielmann, Jan

    2012-01-01

    The hydroboration of 1,1-diphenylethylene (DPE) with catecholborane (HBcat) proceeds at 100 degrees C. For conversion at room temperature three different organocalcium catalysts have been investigated: the calcium hydride complex [DIPPnacnacCaH center dot(THF)](2) (1, DIPPnacnac CH{(CMe)(2,6-iPr(2)C

  16. 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.

  17. 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.

  18. A Proposed Mechanism for the Thermal Denaturation of a Recombinant Bacillus Halmapalus Alpha-amylase - the Effect of Calcium Ions

    Science.gov (United States)

    Nielsen, Anders D.; Pusey, Marc L.; Fuglsang, Claus C.; Westh, Peter

    2003-01-01

    The thermal stability of a recombinant alpha-amylase from Bacillus halmapalus alpha-amylase (BHA) has been investigated using circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC). This alpha-amylase is homologous to other Bacillus alpha-amylases where previous crystallographic studies have identified the existence of 3 calcium binding sites in the structure. Denaturation of BHA is irreversible with a Tm of approximately 89 C, and DSC thermograms can be described using a one-step irreversible model. A 5 C increase in T(sub m) in the presence of 10 fold excess CaCl2 was observed. However, a concomitant increase in the tendency to aggregate was also observed. The presence of 30-40 fold excess calcium chelator (EDTA or EGTA) results in a large destabilization of BHA corresponding to about 40 C lower T(sub m), as determined by both CD and DSC. Ten fold excess EGTA reveals complex DSC thermograms corresponding to both reversible and irreversible transitions, which possibly originate from different populations of BHA:calcium complexes. The observations in the present study have, in combination with structural information of homologous alpha-amylases, provided the basis for the proposal of a simple denaturation mechanism of BHA. The proposed mechanism describes the irreversible thermal denaturation of different BHA:calcium complexes and the calcium binding equilibrium involved. Furthermore, the model accounts for a temperature induced reversible structural change associated with calcium binding.

  19. 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

  20. Calcium: A Nutrient Deserving a Special Issue

    Directory of Open Access Journals (Sweden)

    Susan J. Whiting

    2010-10-01

    Full Text Available Interest in calcium has continued since the 1980s when its role in promoting bone growth and retention was established in clinical trials of children and postmenopausal women. The human nutrition functions now attributed to calcium have expanded beyond bone health to include other conditions such as body weight maintenance. While most efforts have been focused on the findings that dietary intakes are low, there are emerging data on safety concerns of excess amounts. This Special Issue on calcium nutrition, spanning the lifecycle from critically ill neonates through to older adults, has been written by some of the leading researchers in this field.

  1. Sorption of UO22+ on calcium carbonate

    International Nuclear Information System (INIS)

    Sorption of uranyl ions on calcium carbonate from aqueous solutions featuring different concentration of calcium nitrate was studied experimentally. It is shown that uranium sorption decreases with calcium concentration growth in solution, irrespective of the ratio of solid phase and solution masses. Specific sorption of uranium per unit of the sorbent surface depends linearly on the ratio of UO22+ and Ca2+ ions activities in solution with proportionality factor (sorption equilibrium constant) 1.71 ± 0.16 mol/m2 at 20 deg C

  2. Calcium signaling in physiology and pathophysiology

    Institute of Scientific and Technical Information of China (English)

    He-ping CHENG; Sheng WEI; Li-ping WEI; Alexei VERKHRATSKY

    2006-01-01

    Calcium ions are the most ubiquitous and pluripotent cellular signaling molecules that control a wide variety of cellular processes.The calcium signaling system is represented by a relatively limited number of highly conserved transporters and channels,which execute Ca2+ movements across biological membranes and by many thousands of Ca2+-sensitive effectors.Molecular cascades,responsible for the generation of calcium signals,are tightly controlled by Ca2+ ions themselves and by genetic factors,which tune the expression of different Ca2+-handling molecules according to adaptational requirements.Ca2+ ions determine normal physiological reactions and the development of many pathological processes.

  3. Modulation of Intracellular Calcium Levels by Calcium Lactate Affects Colon Cancer Cell Motility through Calcium-Dependent Calpain

    OpenAIRE

    Pasupathi Sundaramoorthy; Jae Jun Sim; Yeong-Su Jang; Siddhartha Kumar Mishra; Keun-Yeong Jeong; Poonam Mander; Oh Byung Chul; Won-Sik Shim; Seung Hyun Oh; Ky-Youb Nam; Hwan Mook Kim

    2015-01-01

    Cancer cell motility is a key phenomenon regulating invasion and metastasis. Focal adhesion kinase (FAK) plays a major role in cellular adhesion and metastasis of various cancers. The relationship between dietary supplementation of calcium and colon cancer has been extensively investigated. However, the effect of calcium (Ca2+) supplementation on calpain-FAK-motility is not clearly understood. We sought to identify the mechanism of FAK cleavage through Ca2+ bound lactate (CaLa), its downstrea...

  4. 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.

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

    OpenAIRE

    Sandra Tavares da Silva; Neuza Maria Brunoro Costa; Frederico Souzalima Caldoncelli Franco; Antônio José Natali

    2013-01-01

    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 a...

  6. Technology obtaining of nitrogen fertilizer from the calcium is containing waste of production of calcium saltpetre

    OpenAIRE

    Власян, Світлана Варужанівна; Шестозуб, Анатолій Борисович; Волошин, Микола Дмитрович

    2013-01-01

    The new technology of obtaining nitrogen fertilizer from calcium-containing sludge of calcium saltpeter production is considered in the paper. The main objective of the research is the development of processing technology of sludge of calcium saltpeter production into alkaline nitrogen fertilizer, analysis of the composition of initial material and finished product, testing of fertilizer by means of vegeta­tive studies and determination of expenditure of drying agent that is exhaust gases of ...

  7. In vivo Calcium Imaging of Evoked Calcium Waves in the Embryonic Cortex

    OpenAIRE

    Yuryev, Mikhail; Pellegrino, Christophe; Jokinen, Ville; Andriichuk, Liliia; Khirug, Stanislav; Khiroug, Leonard; Rivera, Claudio

    2016-01-01

    The dynamics of intracellular calcium fluxes are instrumental in the proliferation, differentiation, and migration of neuronal cells. Knowledge thus far of the relationship between these calcium changes and physiological processes in the developing brain has derived principally from ex vivo and in vitro experiments. Here, we present a new method to image intracellular calcium flux in the cerebral cortex of live rodent embryos, whilst attached to the dam through the umbilical cord. Using this ...

  8. Indium sulfide precipitation from hydrochloric acid solutions of calcium and sodium chlorides

    International Nuclear Information System (INIS)

    The effect of precipitation duration, acid concentration, indium complexing with chloride ions on the process of indium sulfide chemical precipitation in hydrochloric acid solutions, precipitate composition and dispersity are studied. It is established that indium sulfide solubility increases in solutions with acid concentration exceeding 0.40-0.45 mol/l. Calcium and indium chloride addition to diluted hydrochloric solutions greatly increases the solubility of indium sulfide. The effect of calcium chloride on In2S3 solubility is higher than that of sodium chloride

  9. Beetroot-Pigment-Derived Colorimetric Sensor for Detection of Calcium Dipicolinate in Bacterial Spores

    OpenAIRE

    Letícia Christina Pires Gonçalves; Sandra Maria Da Silva; DeRose, Paul C.; Rômulo Augusto Ando; Erick Leite Bastos

    2013-01-01

    In this proof-of-concept study, we describe the use of the main red beet pigment betanin for the quantification of calcium dipicolinate in bacterial spores, including Bacillus anthracis. In the presence of europium(III) ions, betanin is converted to a water-soluble, non-luminescent orange 1∶1 complex with a stability constant of 1.4 × 10(5) L mol(-1). The addition of calcium dipicolinate, largely found in bacterial spores, changes the color of the aqueous solution of [Eu(Bn)(+)] from orange t...

  10. Dielectric spectra of doped and X-ray irradiated calcium fluoride crystals

    International Nuclear Information System (INIS)

    Calcium fluoride crystals doped with PbF2 and codoped with LiF, NaF have been grown using the vertical Bridgman method. The frequency (1-100 kHz) dependence of the real and imaginary parts of the complex dielectric constant, ε1 and ε2, have been studied in the temperature range 160-300 K; the activation parameters of the relaxation process have been determined for various doped and X-irradiated calcium fluoride crystals. The optical absorption spectra of the crystals are also investigated. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Calcium and Cancer Prevention: Strengths and Limits of the Evidence

    Science.gov (United States)

    ... calcium carbonate has about 40 percent elemental calcium, meaning that 500 mg of calcium carbonate actually contains ... in this trial also contained vitamin D (400 international units [ IU ]). During ... and calcium in relation to prostate cancer risk among more than 142, ...

  12. Effects of Adding Chymosin to Milk on Calcium Homeostasis

    DEFF Research Database (Denmark)

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

    2014-01-01

    Calcium intake and absorption is important for bone health. In a randomized double-blind cross-over trial, we investigated effects of adding chymosin to milk on the intestinal calcium absorption as measured by renal calcium excretion and indices of calcium homeostasis. The primary outcome of the...

  13. Assessment of calcium content of lumbarspine by computed tomography

    International Nuclear Information System (INIS)

    Assessment of calcium content of lumbar spine by computed tomography was performed on 76 patients without bone disease and 15 patients with chronic renal failure. Calcium content of medulla and cortex was calculated by CT number. Relationship between calcium content of medulla, cortex and age was discussed. The necessity of midline scan of lumbar spine to obtain the accurate calcium was also stressed. (author)

  14. 21 CFR 172.120 - Calcium disodium EDTA.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium disodium EDTA. 172.120 Section 172.120 Food... Food Preservatives § 172.120 Calcium disodium EDTA. The food additive calcium disodium EDTA (calcium... 100 Promote color retention. 1 By weight of egg yolk portion. (2) With disodium EDTA...

  15. Astrocyte calcium signaling: the third wave.

    Science.gov (United States)

    Bazargani, Narges; Attwell, David

    2016-01-27

    The discovery that transient elevations of calcium concentration occur in astrocytes, and release 'gliotransmitters' which act on neurons and vascular smooth muscle, led to the idea that astrocytes are powerful regulators of neuronal spiking, synaptic plasticity and brain blood flow. These findings were challenged by a second wave of reports that astrocyte calcium transients did not mediate functions attributed to gliotransmitters and were too slow to generate blood flow increases. Remarkably, the tide has now turned again: the most important calcium transients occur in fine astrocyte processes not resolved in earlier studies, and new mechanisms have been discovered by which astrocyte [Ca(2+)]i is raised and exerts its effects. Here we review how this third wave of discoveries has changed our understanding of astrocyte calcium signaling and its consequences for neuronal function. PMID:26814587

  16. Obtainment of calcium carbonate from mussels shell

    International Nuclear Information System (INIS)

    The mussels and oyster shell are discarded at environment, and this accumulation is causing negative consequences to ecosystem. Calcium carbonate is main constituent of the shell chemical composition. Aiming to reduce environmental aggression and generate income to shellfish producer, there was the possibility of using these shells as an alternative to commercial calcium carbonate. For this physics, chemicals and thermal properties were evaluated, using X-ray fluorescence, thermogravimetric analysis, size distribution, abrasiveness and scanning electronic microscopy. The results indicate that mussels shells have an initial degradation temperature higher than commercial calcium carbonate e same lost weight behavior and 95% of shell chemical composition is calcium carbonate. The sample size distribution was influenced by grinding condition and time as well as its abrasiveness. (author)

  17. Modeling and analysis of calcium bromide hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Lottes, Steven A.; Lyczkowski, Robert W.; Panchal, Chandrakant B.; Doctor, Richard D. [Energy Systems Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2009-05-15

    The main focus of this paper is the modeling, simulation, and analysis of the calcium bromide hydrolysis reactor stage in the calcium-bromine thermochemical water-splitting cycle for nuclear hydrogen production. One reactor concept is to use a spray of calcium bromide into steam, in which the heat of fusion supplies the heat of reaction. Droplet models were built up in a series of steps incorporating various physical phenomena, including droplet flow, heat transfer, phase change, and reaction, separately. Given the large heat reservoir contained in a pool of molten calcium bromide that allows bubbles to rise easily, using a bubble column reactor for the hydrolysis appears to be a feasible and promising alternative to the spray reactor concept. The two limiting cases of bubble geometry, spherical and spherical-cap, are considered in the modeling. Results for both droplet and bubble modeling with COMSOL MULTIPHYSICS trademark are presented, with recommendations for the path forward. (author)

  18. Discrete stochastic modeling of calcium channel dynamics

    CERN Document Server

    Baer, M E; Levine, H; Tsimring, L S; Baer, Markus; Falcke, Martin; Levine, Herbert; Tsimring, Lev S.

    1999-01-01

    We propose a simple discrete stochastic model for calcium dynamics in living cells. Specifically, the calcium concentration distribution is assumed to give rise to a set of probabilities for the opening/closing of channels which release calcium thereby changing those probabilities. We study this model in one dimension, analytically in the mean-field limit of large number of channels per site N, and numerically for small N. As the number of channels per site is increased, the transition from a non-propagating region of activity to a propagating one changes in nature from one described by directed percolation to that of deterministic depinning in a spatially discrete system. Also, for a small number of channels a propagating calcium wave can leave behind a novel fluctuation-driven state, in a parameter range where the limiting deterministic model exhibits only single pulse propagation.

  19. Discrete Stochastic Modeling of Calcium Channel Dynamics

    International Nuclear Information System (INIS)

    We propose a discrete stochastic model for calcium dynamics in living cells. A set of probabilities for the opening/closing of calcium channels is assumed to depend on the calcium concentration. We study this model in one dimension, analytically in the limit of a large number of channels per site N , and numerically for small N . As the number of channels per site is increased, the transition from a nonpropagating region of activity to a propagating one changes from one described by directed percolation to that of deterministic depinning in a spatially discrete system. Also, for a small number of channels a propagating calcium wave can leave behind a novel fluctuation-driven state. (c) 2000 The American Physical Society

  20. Synthesis of calcium hydroxyapatite from calcium carbonate and different orthophosphate sources: A comparative study

    International Nuclear Information System (INIS)

    Highlights: ► Calcium hydroxyapatite was synthesized from CaCO3 and four orthophosphates. ► Only H3PO4 led to the complete precipitation of orthophosphate species. ► H3PO4 was also the most efficient for calcium dissolution. ► Reaction pathway was dissolution-precipitation accompanied by agglomeration step. - Abstract: The synthesis of calcium hydroxyapatite (Ca-HA) starting from calcium carbonate and different orthophosphate sources, including orthophosphoric acid, potassium, sodium and ammonium dihydrogen orthophosphates, was investigated under ambient conditions. The reaction started with calcium carbonate dissolution in an acid medium, followed by rapid precipitation of calcium cations with orthophosphate species to form calcium phosphate based particles which were in the size range of 0.4–1 μm. These particles then agglomerated into much larger ones, up to 350 μm in diameter (aggregates). These aggregates possessed an unstable porous structure which was responsible for the porosity of the final products. The highest specific surface area and pore volume were obtained with potassium dihydrogen orthophosphate. On the other hand, orthophosphoric acid led to the highest dissolution of calcium carbonate and the complete precipitation of orthophosphate species. Under ambient conditions, calcium phosphate based solid products of low crystallinity were formed. Different intermediates were identified and a reaction pathway proposed.

  1. Characterization of Calcium Compounds in Opuntia ficus indica as a Source of Calcium for Human Diet

    OpenAIRE

    Isela Rojas-Molina; Elsa Gutiérrez-Cortez; Moustapha Bah; Alejandra Rojas-Molina; César Ibarra-Alvarado; Eric Rivera-Muñoz; Alicia del Real; Ma. de los Angeles Aguilera-Barreiro

    2015-01-01

    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·(H2O)2.375),...

  2. Relating a calcium indicator signal to the unperturbed calcium concentration time-course

    Directory of Open Access Journals (Sweden)

    Abarbanel Henry DI

    2007-02-01

    Full Text Available Abstract Background Optical indicators of cytosolic calcium levels have become important experimental tools in systems and cellular neuroscience. Indicators are known to interfere with intracellular calcium levels by acting as additional buffers, and this may strongly alter the time-course of various dynamical variables to be measured. Results By investigating the underlying reaction kinetics, we show that in some ranges of kinetic parameters one can explicitly link the time dependent indicator signal to the time-course of the calcium influx, and thus, to the unperturbed calcium level had there been no indicator in the cell.

  3. Calcium entry into guinea-pig jejunum cells after calcium stores depletion.

    Science.gov (United States)

    Pacaud, P; Bolton, T B

    1991-01-01

    1) Membrane currents were recorded under voltage-clamp from cells using patch-clamp pipettes. Cells were dialysed with potassium-free caesium solution to block any Ca-activated K-current. The pipette solution contained Indo-1 and the ratio of the emissions from this dye at 480 and 405 nm was used to estimate the free calcium concentration in the cell. 2) Carbachol applied to the cell evoked at -50 mV an initial increase in the intracellular calcium concentration (Cai) followed by a smaller sustained rise (plateau); the changes in inward cationic current (ICarb) closely followed changes in Cai. Calcium entry blockers did not affect these responses. 3) The initial peak in Cai produced by carbachol was due to calcium store release: it was present in calcium-free solution, and unchanged at +50 mV, but it was abolished by prior application of caffeine (10 mM) to the cell or by inclusion of heparin (which blocks D-myoinositol 1,4,5-trisphosphate receptors) in the pipette. 4) The sustained rise (plateau) in Cai produced by carbachol was due to the entry of calcium into the cell down its electrochemical gradient as it was affected by changing the cell membrane potential or the calcium concentration in the bathing solution. As the sustained rise in Cai produced by caffeine had similar properties it was suggested that depletion of calcium stores can evoke an increased calcium entry into the cell through some pathway. PMID:1665265

  4. Effect of Calcium on the Vanadium Extraction from High Calcium Type Stone Coal

    Institute of Scientific and Technical Information of China (English)

    BAO Shenxu; LIANG Liang; ZHANG Yimin; HAN Shihua; HU Yangjia

    2015-01-01

    The high calcium type stone coal from Hubei province was leached by water and dilute acid separately after being roasted with different dosage of NaCl. The water leaching rate of vanadium (WLRV) was low and only 26.8%of vanadium can be leached by water when 4%NaCl was added, but the acid leaching rate of vanadium (ALRV) was relatively high. Calcium in the high calcium type stone coal is greatly superfluous relative to vanadium, hence, the calcium reacts with vanadium to form Ca(VO3)2, Ca2V2O7 and Ca3(VO4)2 orderly during the stone coal roasting process and high temperature is beneficial to the reactions between calcium and vanadium, which was validated by simulated reactions between pure calcium carbonate and vanadium pentoxide. These calcium vanadates are all water insoluble but acid soluble and this causes the low WLRV and relatively high ALRV. After calcium removal by HCl, the WLRV is highly enhanced and reaches about 50%when only 2%NaCl was added. If the HCl content is too high, the stone coal is easily sintered and the formed glass structure can enwrap vanadium, which leads the WLRV to decline. Single water leaching process is not appropriate to extract vanadium from high calcium type stone coal.

  5. Effect of albumin and free calcium concentrations on calcium binding in vitro.

    OpenAIRE

    Besarab, A; DeGuzman, A; Swanson, J W

    1981-01-01

    In vivo equilibrium dialysis studies were performed to define further the characteristics of calcium binding to bovine albumin. The concentration range for albumin (1 to 9 g/dl) as well as ultrafilterable calcium (0.5 to 2.5 mM) studied encompassed those that might be ordinarily encountered in most clinical situations. Major differences in the regressions of total calcium on ultrafilterable calcium occurred at albumin concentrations of 1, 2, and 9 g/dl but only small differences at albumin co...

  6. Study of calcium chloride and calcium nitrate purification on inorganic sorbents

    International Nuclear Information System (INIS)

    Purification of calcium chloride and calcium nitrate from iron, chromium, manganese and cobalt impurities by sorption on some inorganic collectors are considered in this article. Study was conducted by means of radioactive-tracer technique at concurrent use of several γ-radioactive isotopes. As a collectors were used hydrated aluminium and zirconium oxides. Dependence of effectiveness of precipitation by collectors on ph-value of medium, quantity of collector, nature and concentration of components is studied. Optimal parameters of purification of calcium chloride and calcium nitrate are defined.

  7. 21 CFR 201.70 - Calcium labeling.

    Science.gov (United States)

    2010-04-01

    ... product is more than 3.2 grams: “Ask a doctor before use if you have 1 kidney stones a calcium-restricted diet”. The warnings in §§ 201.64(c), 201.70(c), 201.71(c), and 201.72(c) may be combined, if applicable, provided the ingredients are listed in alphabetical order, e.g., a calcium or sodium restricted diet. 1...

  8. Modulation of intestinal absorption of calcium

    International Nuclear Information System (INIS)

    Absorption of ingested calcium (2ml of a 10mM CaCl2 solution + 45Ca) by the adult rat was shown to be facilitated by the simultaneous ingestion of an active carbohydrate, L-arabinose. As the carbohydrate concentration is increased from 10 to 200mM, the absorption of calcium is maximised at a level corresponding to about twice the control absorption level. A similar doubling of calcium absorption is obtained when a 100mM concentration of any one of a number of other carbohydrates is ingested simultaneously with a 10mM CaCl2 solution. Conversely, the simultaneous ingestion of increasing doses (10 to 100mM) of phosphate (NaH2PO4) with a 10mM CaCl2 solution results in decreased 45Ca absorption and retention by the adult rat. The maximum inhibition of calcium absorption by phosphate is independent of the concentration of the ingested calcium solution (from 5 to 50mM CaCl2). The simultaneous ingestion of CaCl2 (10mM) with lactose and sodium phosphate (50 and 10mM respectively) shows that the activation effect of lactose upon 45Ca absorption may be partly dissimulated by the presence of phosphate. These various observations indicate that, within a large concentration range (2 to 50mM CaCl2) calcium absorption appears to be a precisely modulated diffusion process. Calcium absorption varies (between minimum and maximum levels) as a function of the state of saturation by the activators (carbohydrates) and inhibitors (phosphate) of the calcium transport system

  9. Oral calcium supplementation in peripartum dairy cows.

    Science.gov (United States)

    Oetzel, Garrett R

    2013-07-01

    Hypocalcemia in dairy cattle around parturition can be manifest as clinical milk fever or subclinical hypocalcemia. Subclinical hypocalcemia has the greatest economic effect because it affects a much higher proportion of cows. Oral calcium supplements are used to mitigate the effects of both forms of hypocalcemia. Oral calcium supplements are appropriate for cows displaying early clinical signs of hypocalcemia and prophylactically to lessen the negative impacts of hypocalcemia. PMID:23809900

  10. DETERMINATION OF CALCIUM CONTENT IN DIETARY SUPPLEMENTS

    OpenAIRE

    Marjanović-Balaban, Željka R.; Antunović, Vesna R.; Jelić, Dijana R.; Živković, Tanja M.

    2015-01-01

    Calcium is a macro element that is very important for the human body: its content and circulation in the body is large, it serves as the electrolyte, it has a building role and participates in the process of metabolism. The European Union, the World Health Organization (WHO) and the Ministry of Food and Drug (Food and Drug Administration, FDA) gave the RDA (Recommended Dietary Allowances,) for this macro element. The absorption and bioavailability of the calcium may vary depending on a number...

  11. Rickets induced by calcium or phosphate depletion.

    OpenAIRE

    Abugassa, S.; Svensson, O.

    1990-01-01

    We studied the effects of calciopenia and phosphopenia on longitudinal growth, skeletal mineralization, and development of rickets in young Sprague-Dawley rats. At an age of 21 days, two experimental groups were given diets containing 0.02% calcium or 0.02% phosphorus; otherwise the diets were nutritionally adequate. After 7, 14, and 21 days, five animals from each group were randomly chosen. The animals were anaesthetized and blood samples were drawn for analysis of calcium, phosphorus, and ...

  12. Gel time of calcium acrylate grouting material.

    Science.gov (United States)

    Han, Tong-Chun

    2004-08-01

    Calcium acrylate is a polymerized grout, and can polymerize in an aqueous solution. The polymerization reaction utilizes ammonium persulfate as a catalyst and sodium thiosulfate as the activator. Based on the theory of reaction kinetics, this study on the relation between gel time and concentration of activator and catalyst showed that gel time of calcium acrylate is inversely proportional to activator and catalyst concentration. A formula of gel time is proposed, and an example is provided to verify the proposed formula. PMID:15236477

  13. A theory of Plasma Membrane Calcium Pump stimulation and activity

    CERN Document Server

    Graupner, M; Meyer-Hermann, M; Erler, Frido; Graupner, Michael; Meyer-Hermann, Michael

    2003-01-01

    The ATP-driven Plasma Membrane Calcium (PMCA) pump is characterized by a high affinity to calcium and a low transport rate compared to other transmembrane calcium transport proteins. It plays a crucial role for calcium extrusion from cells. Calmodulin is an intracellular calcium buffering protein which is capable in its Calcium-liganded form to stimulate the PMCA pump by increasing both, the affinity to calcium and the maximum calcium transport rate. We introduce a new model of this stimulation process and deduce analytical expressions for experimental observables in order to determine the model parameter on the basis of specific experiments. Furthermore a model for the pumping activity is developed. In contrast to the biological process we have to describe the pumping rate behavior by assuming a ATP:Calcium stoichiometry of 2 in order to reproduce experimental data. The conjunction of the description of calcium pumping and the stimulation model fully and correctly simulates PMCA pump function. Therewith the ...

  14. A calcium-induced calcium release mechanism mediated by calsequestrin.

    Science.gov (United States)

    Lee, Young-Seon; Keener, James P

    2008-08-21

    Calcium (Ca(2+))-induced Ca(2+) release (CICR) is widely accepted as the principal mechanism linking electrical excitation and mechanical contraction in cardiac cells. The CICR mechanism has been understood mainly based on binding of cytosolic Ca(2+) with ryanodine receptors (RyRs) and inducing Ca(2+) release from the sarcoplasmic reticulum (SR). However, recent experiments suggest that SR lumenal Ca(2+) may also participate in regulating RyR gating through calsequestrin (CSQ), the SR lumenal Ca(2+) buffer. We investigate how SR Ca(2+) release via RyR is regulated by Ca(2+) and calsequestrin (CSQ). First, a mathematical model of RyR kinetics is derived based on experimental evidence. We assume that the RyR has three binding sites, two cytosolic sites for Ca(2+) activation and inactivation, and one SR lumenal site for CSQ binding. The open probability (P(o)) of the RyR is found by simulation under controlled cytosolic and SR lumenal Ca(2+). Both peak and steady-state P(o) effectively increase as SR lumenal Ca(2+) increases. Second, we incorporate the RyR model into a CICR model that has both a diadic space and the junctional SR (jSR). At low jSR Ca(2+) loads, CSQs are more likely to bind with the RyR and act to inhibit jSR Ca(2+) release, while at high SR loads CSQs are more likely to detach from the RyR, thereby increasing jSR Ca(2+) release. Furthermore, this CICR model produces a nonlinear relationship between fractional jSR Ca(2+) release and jSR load. These findings agree with experimental observations in lipid bilayers and cardiac myocytes. PMID:18538346

  15. Analytical models of calcium binding in a calcium channel

    International Nuclear Information System (INIS)

    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+ and Ca2+ for [CaCl2] ranging from 10−8 to 10−2 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

  16. 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.

  17. Synthesis of Calcium(II) Amidinate Precursors for Atomic Layer Deposition through a Redox Reaction between Calcium and Amidines.

    Science.gov (United States)

    Kim, Sang Bok; Yang, Chuanxi; Powers, Tamara; Davis, Luke M; Lou, Xiabing; Gordon, Roy G

    2016-08-22

    We have prepared two new Ca(II) amidinates, which comprise a new class of ALD precursors. The syntheses proceed by a direct reaction between Ca metal and the amidine ligands in the presence of ammonia. Bis(N,N'-diisopropylformamidinato)calcium(II) (1) and bis(N,N'-diisopropylacetamidinato)calcium(II) (2) adopt dimeric structures in solution and in the solid state. X-ray crystallography revealed asymmetry in one of the bridging ligands to afford the structure [(η(2) -L)Ca(μ-η(2) :η(2) -L)(μ-η(2) :η(1) -L)Ca(η(2) -L)]. These amidinate complexes showed unprecedentedly high volatility as compared to the widely employed and commercially available Ca(II) precursor, [Ca3 (tmhd)6 ]. In CaS ALD with 1 and H2 S, the ALD window was approximately two times wider and lower in temperature by about 150 °C than previously reported with [Ca3 (tmhd)6 ] and H2 S. Complexes 1 and 2, with their excellent volatility and thermal stability (up to at least 350 °C), are the first homoleptic Ca(II) amidinates suitable for use as ALD precursors. PMID:27351794

  18. The effect of dimethylsulfoxide on the calcium paradox.

    OpenAIRE

    Ruigrok, T. J.; Moes, D.; Slade, A.M.; Nayler, W. G.

    1981-01-01

    Reperfusion of isolated rat hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). Experiments were undertaken to study the effect of dimethylsulfoxide (DMSO) on the occurrence of the calcium paradox in rat heart muscle. DMSO (1.4 mol/l) was added to the calcium-free or the reperfusion medium. Cell damage was quantitated in terms of creatine kinase (CK) release, cardiac electrogram (CEG) changes, and ultras...

  19. Factors to consider in the selection of a calcium supplement.

    OpenAIRE

    Shangraw, R F

    1989-01-01

    Calcium supplements are widely used, yet many questions remain as to the absorption of various calcium salts. Because the solubility of many calcium salts is dependent upon pH, the type of salt used, the condition of the patient, and the time of administration should be considered. Studies show that many calcium supplements on the market today do not meet standards of quality established in the "U.S. Pharmacopeia" (USP). Consumers must be discerning about the products they purchase. Calcium s...

  20. The spatial pattern of atrial cardiomyocyte calcium signalling modulates contraction

    OpenAIRE

    Mackenzie, L; Roderick, H Llewelyn; Berridge, MJ; Conway, SJ; Bootman, MD

    2004-01-01

    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 (~2 μm) intervals throughout atrial myocytes, the ...

  1. Increased absolute calcium binding to albumin in hypoalbuminaemia.

    OpenAIRE

    Besarab, A; Caro, J F

    1981-01-01

    The amount of calcium bound to protein was measured in 30 patients with differing diseases and varying degrees of hypoalbuminaemia. Total serum calcium increased directly with both serum albumin and ultrafilterable calcium concentrations. The estimated amount of calcium bound per gram of albumin varied inversely with the albumin concentration, decreasing from 2.1 to 1.0 mg calcium/g albumin as albumin concentration increased from 1.7 to 3.1 g/dl. Circulating parathyroid hormone (PTH) concentr...

  2. Optical modulation of neurotransmission using calcium photocurrents through the ion channel LiGluR

    Directory of Open Access Journals (Sweden)

    Mercè eIzquierdo-Serra

    2013-03-01

    Full Text Available A wide range of light-activated molecules (photoswitches and phototriggers have been used to the study of computational properties of an isolated neuron by acting pre and postsynaptically. However, new tools are being pursued to elicit a presynaptic calcium influx that triggers the release of neurotransmitters, most of them based in calcium-permeable Channelrhodopsin-2 mutants. Here we describe a method to control exocytosis of synaptic vesicles through the use of a light-gated glutamate receptor (LiGluR, which has recently been demonstrated that supports secretion by means of calcium influx in chromaffin cells. Expression of LiGluR in hippocampal neurons enables reversible control of neurotransmission with light, and allows modulating the firing rate of the postsynaptic neuron with the wavelength of illumination. This method may be useful for the determination of the complex transfer function of individual synapses.

  3. Calcium aluminate cements for nuclear wastes conditioning: literature review and new approaches

    International Nuclear Information System (INIS)

    Encapsulate the diverse wastes produced by nuclear activities in cementitious binders may be very complex due to the adverse cement-waste interactions. Consequences are for example: strong delay, poor mechanical strength or low resistance to leaching. In this case, pure or blended calcium aluminate cements (CACs) may be valuable alternatives. This paper summarises the properties of CAC and blended CAC system and gives some examples from literature where calcium aluminate cements are used for conventional wastes or nuclear wastes conditioning. Moreover, it proposes another approach: using CAC not only as a binder, but also as a chemical reactant. After dissolution calcium aluminates ions can combine with many chemical species (sulphates, nitrates, chlorides, alkali metals, heavy metals) to precipitate specific hydrates allowing chemical trapping of these species. An example is given for the purification of Ni and Zn nitrates solutions. (authors)

  4. Signal processing by T-type calcium channel interactions in the cerebellum

    Science.gov (United States)

    Engbers, Jordan D. T.; Anderson, Dustin; Zamponi, Gerald W.; Turner, Ray W.

    2013-01-01

    T-type calcium channels of the Cav3 family are unique among voltage-gated calcium channels due to their low activation voltage, rapid inactivation, and small single channel conductance. These special properties allow Cav3 calcium channels to regulate neuronal processing in the subthreshold voltage range. Here, we review two different subthreshold ion channel interactions involving Cav3 channels and explore the ability of these interactions to expand the functional roles of Cav3 channels. In cerebellar Purkinje cells, Cav3 and intermediate conductance calcium-activated potassium (IKCa) channels form a novel complex which creates a low voltage-activated, transient outward current capable of suppressing temporal summation of excitatory postsynaptic potentials (EPSPs). In large diameter neurons of the deep cerebellar nuclei, Cav3-mediated calcium current (IT) and hyperpolarization-activated cation current (IH) are activated during trains of inhibitory postsynaptic potentials. These currents have distinct, and yet synergistic, roles in the subthreshold domain with IT generating a rebound burst and IH controlling first spike latency and rebound spike precision. However, by shortening the membrane time constant the membrane returns towards resting value at a faster rate, allowing IH to increase the efficacy of IT and increase the range of burst frequencies that can be generated. The net effect of Cav3 channels thus depends on the channels with which they are paired. When expressed in a complex with a KCa channel, Cav3 channels reduce excitability when processing excitatory inputs. If functionally coupled with an HCN channel, the depolarizing effect of Cav3 channels is accentuated, allowing for efficient inversion of inhibitory inputs to generate a rebound burst output. Therefore, signal processing relies not only on the activity of individual subtypes of channels but also on complex interactions between ion channels whether based on a physical complex or by indirect

  5. Effect of combining different calcium concentration dialysate on calcium balance in peritoneal dialysis patients

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui-ping; WU Bei; LU Li-xia; QIAO Jie; WU Xiang-lan; WANG Mei

    2012-01-01

    Background Calcium and phosphorus metabolic disturbance are common in dialysis patients and associated with increased morbidity and mortality.Therefore,maintaining the balance of calcium and phosphate metabolism and suitable intact parathyroid hormone(iPTH)level has become the focus of attention.We investigated the effects of different peritoneal dialysate calcium concentrations on calcium phosphate metabolism and iPTH in continuous ambulatory peritoneal dialysis(CAPD)patients.Methods Forty stable CAPD patients with normal serum calcium were followed for six months of treatment with 1.25 mmol/L calcium dialysate(DCa1.25,PD4,22 patients)or a combination of 1.75 mmol/L calcium dialysate(DCa1.75,PD2)and PD4(18 patients)twice a day respectively.Total serum calcium(after albumin correction),serum phosphorus,iPTH,alkaline phosphatase(ALP)and blood pressure were recorded before and 1,3 and 6 months after treatment commenced.Results No significant difference was found in baseline serum calcium,phosphorus between the two patient groups,but the levels of iPTH were significantly different.No significant changes were found in the dosage of calcium carbonate and active vitamin D during 6 months.In the PD4 group,serum calcium level at the 1st,3rd,6th months were significantly lower than the baseline(P<0.05).There was no significant difference in serum phosphorus after 6 months treatment.iPTH was significantly higher(P<0.001)at the 1st,3rd,and 6th months compared with the baseline.No differences were seen in ALP and blood pressure.In the PD4+PD2 group,no significant changes in serum calcium,phosphorus,iPTH,ALP and BP during the 6-month follow-up period.Conclusions Treatment with 1.25 mmol/L calcium dialysate for six months can decrease serum calcium,increase iPTH,without change in serum phosphorus,ALP,and BP.The combining of PD4 and PD2 can stabilize the serum calcium and avoid fluctuations in iPTH levels.

  6. Mesoscale crystallization of calcium phosphate nanostructures in protein (casein) micelles

    Science.gov (United States)

    Thachepan, Surachai; Li, Mei; Mann, Stephen

    2010-11-01

    Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60 °C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from β-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35 °C. The presence of Mg2+ ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component β-casein constructs.Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60 °C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from β-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35 °C. The presence of Mg2+ ions in

  7. Increased calcium absorption from synthetic stable amorphous calcium carbonate: Double-blind randomized crossover clinical trial in post-menopausal women

    Science.gov (United States)

    Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (C...

  8. Modelling the transition from simple to complex Ca2+ oscillations in pancreatic acinar cells

    Indian Academy of Sciences (India)

    Neeraj Manhas; James Sneyd; K R Pardasani

    2014-06-01

    A mathematical model is proposed which systematically investigates complex calcium oscillations in pancreatic acinar cells. This model is based on calcium-induced calcium release via inositol trisphosphate receptors (IPR) and ryanodine receptors (RyR) and includes calcium modulation of inositol (1,4,5) trisphosphate (IP3) levels through feedback regulation of degradation and production. In our model, the apical and the basal regions are separated by a region containing mitochondria, which is capable of restricting Ca2+ responses to the apical region. We were able to reproduce the observed oscillatory patterns, from baseline spikes to sinusoidal oscillations. The model predicts that calcium-dependent production and degradation of IP3 is a key mechanism for complex calcium oscillations in pancreatic acinar cells. A partial bifurcation analysis is performed which explores the dynamic behaviour of the model in both apical and basal regions.

  9. Anodic Behavior of Alloy 22 in Calcium Chloride and in Calcium Chloride Plus Calcium Nitrate Brines

    Energy Technology Data Exchange (ETDEWEB)

    Evans, K J; Day, S D; Ilevbare, G O; Whalen, M T; King, K J; Hust, G A; Wong, L L; Estill, J C; Rebak, R B

    2003-05-13

    Alloy 22 (UNS N60622) is a nickel-based alloy, which is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in concentrated calcium chloride (CaCl{sub 2}) brines and to evaluate the inhibitive effect of nitrate, especially to localized corrosion. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion potential of Alloy 22 was approximately -360 mV in the silver-silver chloride (SSC) scale and independent of the tested temperature. Cyclic polarization tests showed that Alloy 22 was mainly susceptible to localized attack in 5 M CaCl{sub 2} at 75 C and higher temperatures. The addition of nitrate in a molar ratio of chloride to nitrate equal to 10 increased the onset of localized corrosion to approximately 105 C. The addition of nitrate to the solution also decreased the uniform corrosion rate and the passive current of the alloy.

  10. Update on calcium pyrophosphate deposition.

    Science.gov (United States)

    Abhishek, Abhishek; Doherty, Michael

    2016-01-01

    Calcium pyrophosphate crystal deposition (CPPD) associates with ageing, osteoarthritis (OA), uncommon metabolic diseases, mutations and polymorphisms in the ankylosis human gene (ANKH). CPPD is frequently polyarticular, occurs due to a generalised articular predisposition, and the association between CPPD and OA is joint specific, for example CPPD associates with knee OA, but not with hip OA. Other recently identified associations include knee malalignment (knee CC), low cortical BMD and soft-tissue calcification. CPPD is generally asymptomatic. A recent study reported that knees with OA plus CC at the index joint, or at distant joints (in absence of index joint CC), were more likely to have attrition. CPPD can cause acute CPP crystal arthritis, chronic CPP crystal inflammatory arthritis, and is frequently present in joints with OA. Joint aspiration remains the gold standard for diagnosing CPPD, although other promising techniques are emerging. Patients with polyarticular or young onset CPPD should be screened for underlying metabolic abnormalities, however, such testing can be unrewarding. The treatment of CPPD is symptomatic. Acute CPP crystal arthritis is treated with rest, local application of ice-packs, joint aspiration, colchicine and/or intra-articular corticosteroid injection (once infection is excluded). Colchicine, low-dose corticosteroids, hydroxychloroquine and radiosynovectomy are recommended for the treatment of chronic or recurrent acute CPP crystal arthritis. Recent RCTs did not confirm any benefit from methotrexate, and although there is increasing interest in the use of anti-IL1 agents for acute or chronic CPP crystal arthritis, their efficacy has not been formally examined. Unlike gout, currently there are no treatments to eliminate CPP crystal deposits. PMID:27586801

  11. Concentration dependent effect of calcium on brain mitochondrial bioenergetics and oxidative stress parameters

    Directory of Open Access Journals (Sweden)

    Patrick G Sullivan

    2013-12-01

    Full Text Available Mitochondrial dysfunction following traumatic brain and spinal cord injury (TBI and SCI plays a pivotal role in the development of secondary pathophysiology and subsequent neuronal cell death. Previously, we demonstrated a loss of mitochondrial bioenergetics in the first 24 h following TBI and SCI initiates a rapid and extensive necrotic event at the primary site of injury. Within the mitochondrial derived mechanisms, the cross talk and imbalance amongst the processes of excitotoxicity, Ca2+ cycling/overload, ATP synthesis, free radical production, and oxidative stress damage ultimately leading to mitochondrial damage followed by neuronal cell death and loss of behaviors. Mitochondria are one of the most important organelles that regulate for intracellular calcium (Ca2+ homeostasis; and are equipped with a tightly regulated Ca2+ transport system. However, owing to the lack of consensus and the link between the downstream effects of calcium in published literature, we undertook a systematic in vitro study for measuring concentration dependent effects of calcium (100-1000 nmols/mg mitochondrial protein on mitochondrial respiration, enzyme activities, reactive oxygen/nitrogen species (ROS/RNS generation, membrane potential (∆Ψ and oxidative damage markers in isolated brain mitochondria. We observed a dose- and time-dependent inhibition of mitochondrial respiration by calcium without influencing mitochondrial pyruvate dehydrogenase complex (PDHC and NADH dehydrogenase (Complex I enzyme activities. We observed dose-dependent decreased production of hydrogen peroxide and total ROS/RNS species generation by calcium and no significant changes in protein and lipid oxidative damage markers. These results may shed new light on the prevailing dogma of the direct effects of calcium on mitochondrial bioenergetics, free radical production and oxidative stress parameters that are primary regulatory mitochondrial mechanisms following neuronal injury.

  12. The GCaMP3 – A GFP-based calcium sensor for imaging calcium dynamics in the human malaria parasite Plasmodium falciparum

    OpenAIRE

    Borges-Pereira, Lucas; Campos, Bruna R.K.L.; Garcia, Celia R. S.

    2014-01-01

    Calcium (Ca2+) signaling pathways are vital for all eukaryotic cells. It is well established that changes in Ca2+ concentration can modulate several physiological processes such as muscle contraction, neurotransmitter secretion and metabolic regulation (Giacomello et al. (2007) [1], Rizzuto and Pozzan (2003) [2]). In the complex life cycle of Plasmodium falciparum, the causative agent of human malaria, Ca2+ is involved in the processes of protein secretion, motility, cell invasion, cell progr...

  13. Disrupted-in-schizophrenia-1 (DISC1) Regulates Endoplasmic Reticulum Calcium Dynamics.

    Science.gov (United States)

    Park, Sung Jin; Jeong, Jaehoon; Park, Young-Un; Park, Kyung-Sun; Lee, Haeryun; Lee, Namgyu; Kim, Sung-Mo; Kuroda, Keisuke; Nguyen, Minh Dang; Kaibuchi, Kozo; Park, Sang Ki

    2015-01-01

    Disrupted-in-schizophrenia-1 (DISC1) has emerged as a convincing susceptibility gene for multiple mental disorders, but its mechanistic link to the pathogenesis of schizophrenia related psychiatric conditions is yet to be further understood. Here, we showed that DISC1 localizes to the outer surface of the endoplasmic reticulum (ER). EXOC1, a subunit of the exocyst complex, interacted with DISC1 and affected its recruitment to inositol-1,4,5-trisphosphate receptor 1 (IP3R1). Notably, knockdown of DISC1 and EXOC1 elicited an exaggerated ER calcium response upon stimulation of IP3R agonists. Similar abnormal ER calcium responses were observed in hippocampal neurons from DISC1-deficient mutant mice. Moreover, perturbation of ER calcium dynamics upon DISC1 knockdown was effectively reversed by treatment with antipsychotic drugs, such as clozapine and haloperidol. These results collectively indicate that DISC1 is a regulatory factor in ER calcium dynamics, linking a perturbed intracellular calcium signaling and schizophrenia pathogenesis. PMID:25732993

  14. Fabrication of highly porous keratin sponges by freeze-drying in the presence of calcium alginate beads

    International Nuclear Information System (INIS)

    Novel fabrication method of highly porous and flexible keratin sponges was developed by combining a particulate-leaching method and a freeze-drying method. Reduced keratin aqueous solution was mixed with dried calcium alginate beads and was lyophilized to give keratin/calcium alginate complex, which was subsequently treated with EDTA solution to leach out calcium alginate beads. The resultant keratin sponge was flexible enough to handle even in dried state because of its quite high porosity (98.9 ± 0.1%), which was brought about by the large and small pores formed by the elimination of calcium alginate beads and water. The sponge supported the attachment and the proliferation of mouse fibroblast cells. Thus, the keratin sponge given by the present fabrication method afforded one alternative as a cell scaffold for tissue engineering

  15. 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 compare

  16. 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...

  17. Calcium ferrite formation from the thermolysis of calcium tris (maleato) ferrate(III)

    Indian Academy of Sciences (India)

    B S Randhawa; Kamaljeet Sweety

    2000-08-01

    For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. 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 thermolysis. In the final stage the ferrite, Ca2Fe2O5, is obtained as a result of solid state reaction between -Fe2O3 and calcium carbonate at 788°C, a temperature much lower than for ceramic method. The results have been compared with those of the oxalate precursor.

  18. Calcium carbonate scaling kinetics determined from radiotracer experiments with calcium-47

    International Nuclear Information System (INIS)

    The deposition rate of calcium carbonate on a heat-transfer surface has been measured using a calcium-47 radiotracer and compared to the measured rate of thermal fouling. The crystalline phase of calcium carbonate that precipitates depends on the degree of supersaturation at the heat-transfer surface, with aragonite precipitating at higher supersaturations and calcite precipitating at lower supersaturations. Whereas the mass deposition rates were constant with time, the thermal fouling rates decreased throughout the course of each experiment as a result of densification of the deposit. It is proposed that the densification was driven by the temperature gradient across the deposit together with the retrograde solubility of calcium carbonate. The temperature dependence of the deposition rate yielded an activation energy of 79 ± 4 kJ/mol for the precipitation of calcium carbonate on a heat-transfer surface. (author)

  19. Skin injuries afflicting three oil workers following contact with calcium bromide and/or calcium chloride.

    Science.gov (United States)

    Saeed, W R; Distante, S; Holmes, J D; Kolhe, P S

    1997-01-01

    Calcium bromide brine is a highly concentrated aqueous solution of calcium bromide and calcium chloride. It is used extensively in the oil industry. This solution and its components are recognized as causes of skin injury and information is available from the manufacturers on their safe use and handling. Two patients who were injured following unprotected skin exposure to this solution and one patient who was injured following exposure to calcium chloride powder are reported. All sustained skin injuries characterised by an absence of pain and a delayed clinical appearance of the full extent of the injury. Furthermore healing was complicated by graft loss or was slow. Although organic bromine compounds are recognized as a cause of skin injuries, no previous reports of such injuries to humans secondary to calcium chloride or bromide exposure were found in the medical literature. Our experience with these patients is described. PMID:9568340

  20. Effect of dietary calcium and phosphorus on intestinal calcium absorption and vitamin D metabolism

    International Nuclear Information System (INIS)

    To understand better dietary regulation of intestinal calcium absorption, a quantitative assessment of the metabolites in plasma and duodenum of rats given daily doses of radioactive vitamin D3 and diets differing in calcium and phosphorus content was made. All known vitamin D metabolites were ultimately identified by high-pressure liquid chromatography. In addition to the known metabolites (25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D3, 1,25-dihydroxyvitamin D3, 25,26-dihydroxyvitamin D3, and 1,24,25-trihydroxyvitamin D3), several new and unidentified metabolites were found. In addition to 1,25-dihydroxyvitamin D3 and 1,24,25-trihydroxyvitamin D3, the levels of some of the unknown metabolites could be correlated with intestinal calcium transport. However, whether or not any of these metabolites plays a role in the stimulation of intestinal calcium absorption by low dietary calcium or low dietary phosphorus remains unknown

  1. Bone calcium turnover during pregnancy and lactation in women with low calcium diets is associated with calcium intake and circulating insulin-like growth factor 1 concentrations

    Science.gov (United States)

    BACKGROUND: Few data exist on longitudinal changes in bone calcium turnover rates across pregnancy and lactation. OBJECTIVE: Our aim was to characterize calcium kinetic variables and predictors of these changes across pregnancy and early lactation in women with low calcium intakes. DESIGN: Stable ca...

  2. Role of calcium in gravity perception of plant roots

    Science.gov (United States)

    Evans, Michael L.

    Calcium ions may play a key role in linking graviperception by the root cap to the asymmetric growth which occurs in the elongation zone of gravistimulated roots. Application of calcium-chelating agents to the root cap inhibits gravitropic curvature without affecting growth. Asymmetric application of calcium to one side of the root cap induces curvature toward the calcium source, and gravistimulation induces polar movement of applied 45Ca2+ across the root cap toward the lower side. The action of calcium may be linked to auxin movement in roots since 1) auxin transport inhibitors interfere both with gravitropic curvature and gravi-induced polar calcium movement and 2) asymmetric application of calcium enhances auxin movement across the elongation zone of gravistimulated roots. Indirect evidence indicates that the calcium-modulated regulator protein, calmodulin, may be involved in either the transport or action of calcium in the gravitropic response mechanism of roots.

  3. Complex Beauty

    OpenAIRE

    Franceschet, Massimo

    2014-01-01

    Complex systems and their underlying convoluted networks are ubiquitous, all we need is an eye for them. They pose problems of organized complexity which cannot be approached with a reductionist method. Complexity science and its emergent sister network science both come to grips with the inherent complexity of complex systems with an holistic strategy. The relevance of complexity, however, transcends the sciences. Complex systems and networks are the focal point of a philosophical, cultural ...

  4. The influence of milk composition on pH and calcium activity measured in situ during heat treatment of reconstituted skim milk.

    Science.gov (United States)

    Chandrapala, Jayani; McKinnon, Ian; Augustin, Mary Ann; Udabage, Punsandani

    2010-08-01

    The pH and calcium activity of reconstituted skim milk solutions (9-21% w/w milk solids non-fat) on heating and after cooling were studied as a function of milk pH prior to heating (pH 6.2-7.2 at 25 degrees C) and added calcium complexing agents (phosphate or EDTA). The pH decreased as the temperature was raised from 25 to 90 degrees C and the magnitude of the pH decrease was greater with increase in initial pH at 25 degrees C before heating or milk concentration. The pH decrease on heating from 25 to 90 degrees C in skim milk solutions with added calcium complexing agents was lower than that of milk without the addition of these salts. The calcium activity decreased on heating from 25 to 60 degrees C. The magnitude of the change decreased with increase in initial pH at 25 degrees C before heating and milk concentration. The decrease in calcium activity on heating from 25 to 60 degrees C for skim milk solutions with added calcium complexing agents was lower than that of milk solutions without the addition of calcium complexing agents. The changes in pH and calcium activity on heating milk were largely reversible after cooling the milk. The results suggested that the pH and calcium activity at high temperatures are a function of the milk composition. Knowledge of the initial pH prior to heating alone is not sufficient for predicting the changes that occur during heating. PMID:20196897

  5. 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.

  6. Vitamin D with Calcium Reduces Mortality

    DEFF Research Database (Denmark)

    Rejnmark, Lars; Avenell, Alison; Masud, Tahir;

    2012-01-01

    ,528 randomized participants (86.8% females) with a median age of 70 (interquartile range, 62-77) yr. Vitamin D with or without calcium reduced mortality by 7% [hazard ratio, 0.93; 95% confidence interval (CI), 0.88-0.99]. However, vitamin D alone did not affect mortality, but risk of death was reduced if vitamin...... D was given with calcium (hazard ratio, 0.91; 95% CI, 0.84-0.98). The number needed to treat with vitamin D plus calcium for 3 yr to prevent one death was 151. Trial level meta-analysis (24 trials with 88,097 participants) showed similar results, i.e. mortality was reduced with vitamin D plus...... 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....

  7. Calcium and bone disorders in pregnancy

    Directory of Open Access Journals (Sweden)

    Shriraam Mahadevan

    2012-01-01

    Full Text Available Significant transplacental calcium transfer occurs during pregnancy, especially during the last trimester, to meet the demands of the rapidly mineralizing fetal skeleton. Similarly, there is an obligate loss of calcium in the breast milk during lactation. Both these result in considerable stress on the bone mineral homeostasis in the mother. The maternal adaptive mechanisms to conserve calcium are different in pregnancy and lactation. During pregnancy, increased intestinal absorption of calcium from the gut mainly due to higher generation of calcitriol (1,25 dihydroxy vitamin D helps in maintaining maternal calcium levels. On the other hand, during lactation, the main compensatory mechanism is skeletal resorption due to increased generation of parathormone related peptide (PTHrP from the breast. Previous studies suggest that in spite of considerable changes in bone mineral metabolism during pregnancy, parity and lactation are not significantly associated with future risk for osteoporosis. However, in India, the situation may not be the same as a significant proportion of pregnancies occur in the early twenties when peak bone mass is not yet achieved. Further, malnutrition, anemia and vitamin D deficiency are commonly encountered in this age group. This may have an impact on future bone health of the mother. It may also probably provide an opportunity for health care providers for prevention. Other metabolic bone diseases like hypoparathyroidism, hyperparathyroidism and pseudohypoparathyroidism are rarely encountered in pregnancy. Their clinical implications and management are also discussed.

  8. Calcium And Zinc Deficiency In Preeclamptic Women

    Directory of Open Access Journals (Sweden)

    Sultana Ferdousi

    2011-12-01

    Full Text Available Background: Pre-eclampsia is the most common medical complication of pregnancy associated withincreased maternal and infant mortality and morbidity. Reduced serum calcium and zinc levels arefound associated with elevated blood pressure in preeclampsia. Objective: To observe serum calciumand zinc levels in preeclamptic women. Methods: This cross sectional study was carried out in theDepartment of Physiology, Bangabandhu Sheikh Mujib Medical University, Shahbag, Dhaka betweenJuly 2009 to June 2010. In this study, 60 pregnant women of preeclampsia, aged 18-39 years withgestational period more than 20th weeks were included as the study (group B. For comparison ageand gestational period matched 30 normotensive pregnant women control (group A were also studied.All the subjects were selected from Obstetric and Gynae In and Out patient Department of BSMMUand Dhaka Medical College Hospital. Serum calcium was measured by Colorimetric method and serumzinc was measured by Spectrophotometric method. Data were analysed by independent sample t testand Pearson’s correlation coefficient test. Results: Mean serum calcium and zinc levels weresignificantly (p<0.001 lower in study group than those of control group. Again, serum calcium andzinc showed significant negative correlation with SBP and DBP in preeclamptic women. Conclusion:This study concludes that serum calcium and zinc deficiency may be one of the risk factor ofpreeclampsia. Therefore, early detection and supplementation to treat this deficiency may reduce theincidence of preeclampsia.

  9. 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.

  10. A protein involved in the assembly of an extracellular calcium storage matrix.

    Science.gov (United States)

    Glazer, Lilah; Shechter, Assaf; Tom, Moshe; Yudkovski, Yana; Weil, Simy; Aflalo, Eliahu David; Pamuru, Ramachandra Reddy; Khalaila, Isam; Bentov, Shmuel; Berman, Amir; Sagi, Amir

    2010-04-23

    Gastroliths, the calcium storage organs of crustaceans, consist of chitin-protein-mineral complexes in which the mineral component is stabilized amorphous calcium carbonate. To date, only three proteins, GAP 65, gastrolith matrix protein (GAMP), and orchestin, have been identified in gastroliths. Here, we report a novel protein, GAP 10, isolated from the gastrolith of the crayfish Cherax quadricarinatus and specifically expressed in its gastrolith disc. The encoding gene was cloned by partial sequencing of the protein extracted from the gastrolith matrix. Based on an assembled microarray cDNA chip, GAP 10 transcripts were found to be highly (12-fold) up-regulated in premolt gastrolith disc and significantly down-regulated in the hypodermis at the same molt stage. The deduced protein sequence of GAP 10 lacks chitin-binding domains and does not show homology to known proteins in the GenBank data base. It does, however, have an amino acid composition that has similarity to proteins extracted from invertebrate and ascidian-calcified extracellular matrices. The GAP 10 sequence contains a predicted signal peptide and predicted phosphorylation sites. In addition, the protein is phosphorylated and exhibits calcium-binding ability. Repeated daily injections of GAP 10 double strand RNA to premolt C. quadricarinatus resulted in a prolonged premolt stage and in the development of gastroliths with irregularly rough surfaces. These findings suggest that GAP 10 may be involved in the assembly of the gastrolith chitin-protein-mineral complex, particularly in the deposition of amorphous calcium carbonate. PMID:20150428

  11. Association of Urinary Calcium Excretion with Serum Calcium and Vitamin D Levels

    Science.gov (United States)

    Rathod, Anita; Bonny, Olivier; Guessous, Idris; Suter, Paolo M.; Conen, David; Erne, Paul; Binet, Isabelle; Gabutti, Luca; Gallino, Augusto; Muggli, Franco; Hayoz, Daniel; Péchère-Bertschi, Antoinette; Paccaud, Fred

    2015-01-01

    Background and objectives Population-based data on urinary calcium excretion are scarce. The association of serum calcium and circulating levels of vitamin D [25(OH)D2 or D3] with urinary calcium excretion in men and women from a population-based study was explored. Design, settings, participants, & measurements Multivariable linear regression was used to explore factors associated with square root–transformed 24-hour urinary calcium excretion (milligrams per 24 hours) taken as the dependent variable with a focus on month-specific vitamin D tertiles and serum calcium in the Swiss Survey on Salt Study. Results In total, 624 men and 669 women were studied with mean ages of 49.2 and 47.0 years, respectively (age range=15–95 years). Mean urinary calcium excretion was higher in men than in women (183.05 versus 144.60 mg/24 h; P<0.001). In adjusted models, the association (95% confidence interval) of square root urinary calcium excretion with protein–corrected serum calcium was 1.78 (95% confidence interval, 1.21 to 2.34) mg/24 h per milligram per deciliter in women and 0.59 (95% confidence interval, −0.11 to 1.29) mg/24 h per milligram per deciliter in men. Men in the third 25(OH)D3 tertile had higher square root urinary calcium excretion than men in the first tertile (0.99; 95% confidence interval, 0.36 to 1.63 mg/24 h per nanogram per milliliter), and the corresponding association was 0.32 (95% confidence interval, −0.22 to 0.85) mg/24 h per nanogram per milliliter in women. These sex differences were more marked under conditions of high urinary sodium or urea excretions. Conclusions There was a positive association of serum calcium with urinary calcium excretion in women but not men. Vitamin 25(OH)D3 was associated with urinary calcium excretion in men but not women. These results suggest important sex differences in the hormonal and dietary control of urinary calcium excretion. PMID:25518946

  12. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Palkovic, Steven D.; Moeini, Sina; Büyüköztürk, Oral, E-mail: obuyuk@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Yip, Sidney [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-07-21

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  13. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    International Nuclear Information System (INIS)

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces

  14. Luminescent properties of calcium iodide crystals

    International Nuclear Information System (INIS)

    The influence of preparation conditions, temperature and X radiation on luminescent properties of calcium iodide scintillating crystals is studied, the results are provided. The results obtained when studying spectral characteristics of CaI2 and CaI2:H2 crystals in case of optical and X-ray excitation in the temperature range of 90-400 K, allowance made for data obtained when studying luminescent properties of calcium iodide crystals activated by Cl-, Br-, OH- and Ca2+ impurities, permit assumption that band 236 nm observed in excitation spectra of calcium iodide crystals can stem from noncontrolled hydrogen impurity. Luminescence of the crystals with the maximum in the range of 395 nm is assigned to radiation recombination of excitons localized on H- ions

  15. Calcium metabolism evaluated by 47Ca kinetics

    International Nuclear Information System (INIS)

    Optimization of a four-crystal stretcher geometry whole-body (WB) counter was performed. The measured geometric characteristic did not differ significantly from the theoretically calculated characteristic (p>0.05). The linearity of the WB counter was high in the range 3.7 kBq to 3.7 MBq. Longtime variability of local background was CV = 3.7 per cent. In vivo sensitivity was calculated to 18 cpm/kBq and the detection limit to about 5 kBq. The reproducibility was estimated to 0.7 per cent. The WB counter was used in 47Ca turnover and calcium balance studies of 15 normal individuals. The data were analysed according to a modification of the expanding calcium pool model using an improved Bauer-Carlsson-Lindquist formulation. Variability and method errors of main parameters for calcium metabolism were evaluated. (Auth.)

  16. Glial calcium signaling in physiology and pathophysioilogy

    Institute of Scientific and Technical Information of China (English)

    Alexei VERKHRASKY

    2006-01-01

    Neuronal-glial circuits underlie integrative processes in the nervous system.Function of glial syncytium is,to a very large extent,regulated by the intracellular calcium signaling system.Glial calcium signals are triggered by activation of multiple receptors,expressed in glial membrane,which regulate both Ca2+ entry and Ca2+ release from the endoplasmic reticulum.The endoplasmic reticulum also endows glial cells with intracellular excitable media,which is able to produce and maintain long-ranging signaling in a form of propagating Ca2+ waves.In pathological conditions,calcium signals regulate glial response to injury,which might have both protective and detrimental effects on the nervous tissue.

  17. Influence of ferrite phase in alite-calcium sulfoaluminate cements

    Science.gov (United States)

    Duvallet, Tristana Yvonne Francoise

    Since the energy crisis in 1970's, research on low energy cements with low CO2- emissions has been increasing. Numerous solutions have been investigated, and the goal of this original research is to create a viable hybrid cement with the components of both Ordinary Portland cement (OPC) and calcium sulfoaluminate cement (CSAC), by forming a material that contains both alite and calcium sulfoaluminate clinker phases. Furthermore, this research focuses on keeping the cost of this material reasonable by reducing aluminum requirements through its substitution with iron. The aim of this work would produce a cement that can use large amounts of red mud, which is a plentiful waste material, in place of bauxite known as an expensive raw material. Modified Bogue equations were established and tested to formulate this novel cement with different amounts of ferrite, from 5% to 45% by weight. This was followed by the production of cement from reagent chemicals, and from industrial by-products as feedstocks (fly ash, red mud and slag). Hydration processes, as well as the mechanical properties, of these clinker compositions were studied, along with the addition of gypsum and the impact of a ferric iron complexing additive triisopropanolamine (TIPA). To summarize this research, the influence of the addition of 5-45% by weight of ferrite phase, was examined with the goal of introducing as much red mud as possible in the process without negatively attenuate the cement properties. Based on this PhD dissertation, the production of high-iron alite-calcium sulfoaluminateferrite cements was proven possible from the two sources of raw materials. The hydration processes and the mechanical properties seemed negatively affected by the addition of ferrite, as this phase was not hydrated entirely, even after 6 months of curing. The usage of TIPA counteracted this decline in strength by improving the ferrite hydration and increasing the optimum amount of gypsum required in each composition

  18. Effects of calcium chelators on calcium distribution and protein solubility in rennet casein dispersions.

    Science.gov (United States)

    McIntyre, Irene; O' Sullivan, Michael; O' Riordan, Dolores

    2016-04-15

    This study investigated the effects of calcium chelating salts on calcium-ion activity (ACa(++)), calcium distribution, and protein solubility in model CaCl2 solutions (50 mmol L(-1)) or rennet casein dispersions (15 g/100 g). Disodium phosphate and trisodium citrate at concentrations of 10 and 30 mmol L(-1) and at ratios of 1:0, 2:1, 1:1, 1:2 and 0:1 were added to both systems. The CaCl2 system, despite its simplicity, was a good indicator of chelating salt-calcium interactions in rennet casein dispersions. Adding trisodium citrate either alone or as part of a mixed chelating salt system resulted in high levels of dispersed "chelated" calcium; conversely, disodium phosphate addition resulted in lower levels, while the ACa(++) decreased with increasing concentration of both chelating salts. Neither chelating salt produced high levels of soluble protein. Thus calcium chelating salts may play a more subtle role in modulating hydration during manufacture of casein-based matrices than simply solubilising calcium or protein. PMID:26616945

  19. Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

    Science.gov (United States)

    Komar, N.; Zeebe, R. E.

    2016-01-01

    Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (˜252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here we identify the deficiencies of a simplified calcium model employed in several previous studies, and we demonstrate the importance of a fully coupled carbon cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of >6°C.

  20. 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.

  1. Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

    Science.gov (United States)

    Komar, Nemanja; Zeebe, Richard

    2016-04-01

    Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (˜252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here, we identify the deficiencies of a simplified calcium model employed in several previous studies and we demonstrate the importance of a fully coupled carbon-cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the LOSCAR model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of >6oC.

  2. STUDY OF SERUM TOTAL CALCIUM, IO NIZED CALCIUM AND TOTAL PROTEIN CONCENTRATIONS IN POSTMENOPAUSAL WOMEN

    Directory of Open Access Journals (Sweden)

    SK.Deepthi

    2015-05-01

    Full Text Available Menopause and ageing is associated with accelerated loss of cortical bone. Osteoporotic fractures are common cause of morbidity and mortality in adult Indian women due to ageing. This study was conducted to evaluate the levels of serum calcium, ionized calcium and total protein levels in postmenopausal women and to assess its relation with ageing. Study includes 70 women (40 post menopausal and 30 prem enopausal women serum alkaline phosphatase, serum calcium, ionized calcium and total proteins, serum albumin were estimated in both cases and controls. There is decrease in serum calcium in postmenopausal; wo men when compared to premenopausal women. There was no significant change in ionized calcium in both cases and controls. ALP is highly significant P<0.001. In postmenopausal women suggesting there is high alkaline phosphotase activity in postmenopausal women as a result of the inhibitory effects of estrogen on bone turnover rate which is dependent on age and body mass index. Decrease in serum albumin was seen in postmenopausal wo men which is the reason for decrease in serum calcium level which is inturn related to ageing effect.

  3. Calcium deposits in the common carotid artery

    International Nuclear Information System (INIS)

    Complete text of publication follows. Arterial calcification consists mainly of calcium apatite and takes place at two sites in the vessel wall: the intima and the media. Intimal calcification occurs exclusively within atherosclerotic plaques, while medial calcification may develop independently [1]. Ultrasound examination of the carotid arteries is performed routinely to assess pathological alterations. Large calcified plaques in the carotid arteries can be detected by B-mode ultrasonography easily as high frequency ultrasound does not penetrate calcium and have been investigated extensively. In this study our aim was to determine the calcium distribution in the vessel wall itself, excluding large plaques, and to make the first step towards investigating the relationship between the calcium distributional maps and the respective ultrasonic images. The carotid arteries of five elderly (age 71±9 years) and one young (age 27 years) deceased patients were excised at autopsy and were investigated with a medical ultrasound equipment in a tank containing saline solution. Scan sequences were videotaped and images of previously marked cross-sections were transferred to a computer. Small pieces of the arteries were cut and quench frozen. Sections of 60μm from the middle of the scanned segments (30mm proximal to the bifurcation) were cut in a cryostat. The cryosections were transferred to microprobe target holders. The elemental distribution of the samples were determined by particle induced X-ray emission (PIXE) at the Debrecen microprobe [2]. True elemental maps and absolute concentration values were evaluated with a new software (True Pixe Imaging) [3]. The average calcium content of the scanned areas varied between 1000 and 9000μg/g in the slices of the common carotid arteries of the elderly patients. In contrast, scanned areas in the slices from the young subject contained only 600-800μg/g calcium. The concentration of calcium could reach even 3.75% along the wide

  4. NMR study of hydrated calcium silicates

    International Nuclear Information System (INIS)

    Radioactive wastes storage methods are developed by the CEA. As cements are important materials as well for hours living radioisotopes than for years living radioisotopes, a better knowledge of this material will allow to anticipate its behaviour and to obtain safer storage methods. The structure of calcium silicates (C-S-H) (main constituent of cements) have then been determined in this thesis by nuclear magnetic resonance. This method has allow to explain in structural terms, the different calcium rates that can be measured in the C-S-H too. (O.M.)

  5. Synthesis and characterization of porous calcium phosphate

    International Nuclear Information System (INIS)

    The porous calcium phosphate was prepared by the continuous precipitation method using Ca(NO3)2.4H2O and NH4H2PO4 salts. The synthesized material was structurally and superficially characterized using the XRD, BET, IR TGA and SEM techniques. The obtained inorganic material was identified as calcium phosphate that presents a great specific area for what can be efficiently used as adsorbent material for adsorption studies in the radioactive wastes treatment present in aqueous solution. (Author)

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

    OpenAIRE

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

    2012-01-01

    Chronic kidney disease (CKD) patients are given calcium carbonate to bind dietary phosphorus and reduce phosphorus retention, and to prevent negative calcium balance. Data are limited on calcium and phosphorus balance in CKD to support this. The aim of this study was to determine calcium and phosphorus balance and calcium kinetics with and without calcium carbonate in CKD patients. Eight stage 3/4 CKD patients, eGFR 36 mL/min, participated in two 3-week balances in a randomized placebo-contro...

  7. Complex chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bong Gon; Kim, Jae Sang; Kim, Jin Eun; Lee, Boo Yeon

    2006-06-15

    This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

  8. Complex chemistry

    International Nuclear Information System (INIS)

    This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

  9. 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 calc

  10. Sulfhydryl oxidation overrides Mg(2+) inhibition of calcium-induced calcium release in skeletal muscle triads.

    OpenAIRE

    Donoso, P; Aracena, P; Hidalgo, C.

    2000-01-01

    We studied the effect of oxidation of sulfhydryl (SH) residues on the inhibition by Mg(2+) of calcium-induced calcium release (CICR) in triad-enriched sarcoplasmic reticulum vesicles isolated from rabbit skeletal muscle. Vesicles were either passively or actively loaded with calcium before eliciting CICR by dilution at pCa 4.6-4.4 in the presence of 1.2 mM free [ATP] and variable free [Mg(2+)]. Native triads exhibited a significant inhibition of CICR by Mg(2+), with a K(0.5) approximately 50 ...

  11. Intolerance to oral and intravenous calcium supplements in atopic eczema.

    OpenAIRE

    Devlin, J; David, T J

    1990-01-01

    Children treated with dietary restriction for food intolerance may require calcium supplementation, particularly if cows' milk and milk substitutes are not tolerated. We report two children with atopic eczema who reacted adversely to a number of calcium supplement formulations.

  12. Electroreduction of uranyl ion in aqueous calcium nitrate solutions

    International Nuclear Information System (INIS)

    The electroreduction of uranyl ions in buffered and unbuffered 0.5 M calcium nitrate has been studied using polarography, cyclic voltammetry, chronopotentiometry, and chronoamperometry. The results are compared with those in molten calcium nitrate tetrahydrate. (author)

  13. Calcium Supplements Might Raise Older Women's Dementia Risk

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_160508.html Calcium Supplements Might Raise Older Women's Dementia Risk Finding ... 2016 WEDNESDAY, Aug. 17, 2016 (HealthDay News) -- Taking calcium supplements with the hope of keeping osteoporosis at ...

  14. Molecular structure and pathophysiological roles of the Mitochondrial Calcium Uniporter.

    Science.gov (United States)

    Mammucari, Cristina; Raffaello, Anna; Vecellio Reane, Denis; Rizzuto, Rosario

    2016-10-01

    Mitochondrial Ca(2+) uptake regulates a wide array of cell functions, from stimulation of aerobic metabolism and ATP production in physiological settings, to induction of cell death in pathological conditions. The molecular identity of the Mitochondrial Calcium Uniporter (MCU), the highly selective channel responsible for Ca(2+) entry through the IMM, has been described less than five years ago. Since then, research has been conducted to clarify the modulation of its activity, which relies on the dynamic interaction with regulatory proteins, and its contribution to the pathophysiology of organs and tissues. Particular attention has been placed on characterizing the role of MCU in cardiac and skeletal muscles. In this review we summarize the molecular structure and regulation of the MCU complex in addition to its pathophysiological role, with particular attention to striated muscle tissues. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou. PMID:26968367

  15. Growth of calcium sulphate deposits on heated wall

    International Nuclear Information System (INIS)

    As distillation processes are used to desalinate sea water, salt deposit (or scaling) under the form of crystals on heat exchange surfaces is one of the main difficulties for these processes. Addressing the case of calcium sulphate solution instead of the more complex case of sea water, this research thesis first recalls theoretical, thermodynamic and kinetic data involved in precipitation, and aims at determining the kinetic law and growth mechanism. Precipitation of hemihydrate is experimentally studied in transient regime with a forced circulation without boiling along a heated wall, then with natural circulation with boiling occurring on the wall. A model is proposed to explain the experimentally determined kinetic law. A study in permanent regime is performed to analyze operating conditions of a heat exchanger. In-thickness growth rate of the hemihydrate is obtained from the evolution of the thermal resistance due to deposits. The inhibiting influence of iron is outlined

  16. Calcium absorption from corn tortilla is relatively high and is dependent upon calcium content and liming in Mexican women.

    Science.gov (United States)

    Rosado, Jorge L; Díaz, Margarita; Rosas, Angélica; Griffit, Ian; García, Olga P

    2005-11-01

    Corn tortillas are the staple food of Mexico. During their preparation, calcium is added to the tortillas; therefore, tortillas are the main source of calcium for a large proportion of the population. The bioavailability of calcium from lime-treated tortillas in humans is not known. The objectives of the present study were to determine calcium absorption from corn tortilla, to determine the effect of lime treatment on calcium absorption from corn tortilla, and to compare calcium absorption from tortilla prepared with a commercial corn flour and tortillas prepared with the traditional lime treatment at home. Nonpregnant, nonlactating women (n = 9) were administered 3 different treatments: 1) 180 g of corn tortilla prepared from corn flour with no lime treatment (CF), 2) 180 g of corn tortilla prepared from lime-treated commercial corn flour (LTCCF), or 3) 180 g of corn tortillas prepared from lime-treated home-prepared corn flour (LTHCF). Calcium absorption was measured using an established dual-tracer stable isotope technique. Calcium absorption of CF, LTCCF, and LTHCF was (mean +/- SD): 44 +/- 3.2, 32 +/- 4.4, and 30 +/- 2.4%, respectively; the fractional calcium absorption from CF differed from that of either LTCCF or LTHCF (P tortillas is high and dependent on calcium concentration. The addition of calcium during lime treatment increases calcium concentration and total calcium absorption. PMID:16251614

  17. Inulin and fructooligosaccharide affect in vitro calcium uptake and absorption from calcium-enriched gluten-free bread.

    Science.gov (United States)

    Krupa-Kozak, U; Swiątecka, D; Bączek, N; Brzóska, M M

    2016-04-20

    Compromised intestinal calcium absorption affecting a deterioration of bone state is a sign of coeliac disease. Experimental calcium-fortified gluten-free bread (GFB) of improved calcium bioavailability could increase calcium content in the diets of coeliac disease patients, allowing them to obtain the amount of calcium they need for therapeutic use. Prebiotics, including inulin-type fructans (IFs) have a beneficial effect on calcium bioavailability. In the present study, the in vitro model composed of the intestinal-like Caco-2 cells and the human intestinal bacteria (Lactobacillus, Enterococcus and Enterobacteriaceae) were used to analyse the effect of inulin and fructooligosaccharide (FOS) of different chain lengths, on calcium uptake and absorption from experimental GFB. Analysed IFs, especially short-chain FOS, significantly (p < 0.05) increased cellular calcium uptake from GFB digest and stimulated the intestinal bacteria applied in the cultures to the intensive synthesis of organic acids. In particular, the concentration of butyric, valeric and lactic acids increased significantly. Similarly, in the calcium absorption experiment, IFs increased the cellular calcium retention but concomitantly reduced its content in basolateral filtrates. The results obtained suggest that the applied IFs affected differentially calcium uptake and absorption from the experimental calcium-enriched GFB, therefore a further study is needed to assess whether these observations made in vitro contribute to IF effects on calcium absorption from experimental GFB in vivo. PMID:26965706

  18. Calcium induced regulation of skeletal troponin--computational insights from molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Georgi Z Genchev

    Full Text Available The interaction between calcium and the regulatory site(s of striated muscle regulatory protein troponin switches on and off muscle contraction. In skeletal troponin binding of calcium to sites I and II of the TnC subunit results in a set of structural changes in the troponin complex, displaces tropomyosin along the actin filament and allows myosin-actin interaction to produce mechanical force. In this study, we used molecular dynamics simulations to characterize the calcium dependent dynamics of the fast skeletal troponin molecule and its TnC subunit in the calcium saturated and depleted states. We focused on the N-lobe and on describing the atomic level events that take place subsequent to removal of the calcium ion from the regulatory sites I and II. A main structural event - a closure of the A/B helix hydrophobic pocket results from the integrated effect of the following conformational changes: the breakage of H-bond interactions between the backbone nitrogen atoms of the residues at positions 2, 9 and sidechain oxygen atoms of the residue at position 12 (N(2-OE(12/N(9-OE(12 in sites I and II; expansion of sites I and II and increased site II N-terminal end-segment flexibility; strengthening of the β-sheet scaffold; and the subsequent re-packing of the N-lobe hydrophobic residues. Additionally, the calcium release allows the N-lobe to rotate relative to the rest of the Tn molecule. Based on the findings presented herein we propose a novel model of skeletal thin filament regulation.

  19. Glutamate-induced glutamate release: A proposed mechanism for calcium bursting in astrocytes

    Science.gov (United States)

    Larter, Raima; Craig, Melissa Glendening

    2005-12-01

    Here we present a new model for the generation of complex calcium-bursting patterns in astrocytes, a type of brain cell recently implicated in a variety of neural functions including memory formation. The model involves two positive feedback processes, in which the key feedback species are calcium ion and glutamate. The latter is the most abundant excitatory neurotransmitter in the brain and has been shown to be involved in bidirectional communication between astrocytes and nearby neurons. The glutamate feedback process considered here is shown to be critical for the generation of complex bursting oscillations in the astrocytes and to, perhaps, code for information which may be passed from neuron to neuron via the astrocyte. These processes may be involved in memory storage and formation as well as in mechanisms which lead to dynamical diseases such as epilepsy.

  20. Studying inhibition of calcium oxalate stone formation: an in vitro approach for screening hydrogen sulfide and its metabolites

    Directory of Open Access Journals (Sweden)

    S. Vaitheeswari

    2015-06-01

    Full Text Available ABSTRACTPurpose:Calcium oxalate urolithiasis is one of the most common urinary tract diseases and is of high prevalence. The present study proposes to evaluate the antilithiatic property of hydrogen sulfide and its metabolites like thiosulfate & sulfate in an in vitro model.Materials and Methods:The antilithiatic activity of sodium hydrogen sulfide (NaSH, sodium thiosulfate (Na2S2O3 and sodium sulfate (Na2SO4 on the kinetics of calcium oxalate crystal formation was investigated both in physiological buffer and in urine from normal and recurrent stone forming volunteers. The stones were characterized by optical and spectroscopic techniques.Results:The stones were characterized to be monoclinic, prismatic and bipyramidal habit which is of calcium monohydrate and dihydrate nature. The FTIR displayed fingerprint corresponding to calcium oxalate in the control while in NaSH treated, S=O vibrations were visible in the spectrum. The order of percentage inhibition was NaSH>Na2S2O3>Na2SO4.Conclusion:Our study indicates that sodium hydrogen sulfide and its metabolite thiosulfate are inhibitors of calcium oxalate stone agglomeration which makes them unstable both in physiological buffer and in urine. This effect is attributed to pH changes and complexing of calcium by S2O32-and SO42- moiety produced by the test compounds.

  1. Calcium phosphate mineralization is widely applied in crustacean mandibles

    OpenAIRE

    Shmuel Bentov; Aflalo, Eliahu D.; Jenny Tynyakov; Lilah Glazer; Amir Sagi

    2016-01-01

    Crustaceans, like most mineralized invertebrates, adopted calcium carbonate mineralization for bulk skeleton reinforcement. Here, we show that a major part of the crustacean class Malacostraca (which includes lobsters, crayfishes, prawns and shrimps) shifted toward the formation of calcium phosphate as the main mineral at specified locations of the mandibular teeth. In these structures, calcium phosphate is not merely co-precipitated with the bulk calcium carbonate but rather creates speciali...

  2. The stability mechanisms of an injectable calcium phosphate ceramic suspension.

    OpenAIRE

    Fatimi, Ahmed; Tassin, Jean-François; Axelos, Monique; Weiss, Pierre

    2010-01-01

    Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of "ready to use" injectable biomaterial. But, during storage...

  3. Coupling Effect of Ion Channel Clusters on Calcium Signalling

    International Nuclear Information System (INIS)

    Based on a modified intracellular Ca2+ model involving diffusive coupling of two calcium ion channel clusters, the effects of coupling on calcium signalling are numerically investigated. The simulation results indicate that the diffusive coupling of clusters together with internal noise determine the calcium dynamics of single cluster, and for either homogeneous or heterogeneous coupled clusters, the synchronization of clusters, which is important to calcium signalling, is enhanced by the coupling effect

  4. Altered calcium metabolism in aging CA1 hippocampal pyramidal neurons

    OpenAIRE

    Oh, M. Matthew; Oliveira, Fernando A.; Waters, Jack; Disterhoft, John F.

    2013-01-01

    Altered neuronal calcium homeostasis is widely hypothesized to underlie cognitive deficits in normal aging subjects, but the mechanisms that underlie this change are unknown, possibly due to a paucity of direct measurements from aging neurons. Using CCD and two-photon calcium imaging techniques on CA1 pyramidal neurons from young and aged rats, we show that calcium influx across the plasma membrane increases with aging, and that this change is countered by increased intracellular calcium buff...

  5. 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.

  6. 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.

  7. Calcium Intake in Elderly Australian Women Is Inadequate

    OpenAIRE

    Colin W. Binns; Xingqiong Meng; Kerr, Deborah A; Kun Zhu; Amanda Devine; Vicky Solah; Richard L. Prince

    2010-01-01

    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...

  8. Coupling Effect of Ion Channel Clusters on Calcium Signalling

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; JIA Ya; YI Ming; MA Jun; YU Guang

    2008-01-01

    @@ Based on a modified intracellular Ca2+ model involving diffusive coupling of two calcium ion channel clusters,the effects of coupling on calcium signalling are numerically investigated.The simulation results indicate that the diffusive coupling of clusters together with internal noise determine the calcium dynamics of single cluster,and for either homogeneous or heterogeneous coupled clusters,the synchronization of clusters,which is important to calcium signalling,is enhanced by the coupling effect.

  9. Calcium Ions in Inherited Cardiomyopathies.

    Science.gov (United States)

    Deftereos, Spyridon; Papoutsidakis, Nikolaos; Giannopoulos, Georgios; Angelidis, Christos; Raisakis, Konstantinos; Bouras, Georgios; Davlouros, Periklis; Panagopoulou, Vasiliki; Goudevenos, John; Cleman, Michael W; Lekakis, John

    2016-01-01

    Inherited cardiomyopathies are a known cause of heart failure, although the pathways and mechanisms leading from mutation to the heart failure phenotype have not been elucidated. There is strong evidence that this transition is mediated, at least in part, by abnormal intracellular Ca(2+) handling, a key ion in ventricular excitation, contraction and relaxation. Studies in human myocytes, animal models and in vitro reconstituted contractile protein complexes have shown consistent correlations between Ca(2+) sensitivity and cardiomyopathy phenotype, irrespective of the causal mutation. In this review we present the available data about the connection between mutations linked to familial hypertrophic (HCM), dilated (DCM) and restrictive (RCM) cardiomyopathy, right ventricular arrhythmogenic cardiomyopathy/dysplasia (ARVC/D) as well as left ventricular non-compaction and the increase or decrease in Ca(2+) sensitivity, together with the results of attempts to reverse the manifestation of heart failure by manipulating Ca(2+) homeostasis. PMID:26411603

  10. Phosphorylation of erythrocyte membrane liberates calcium

    International Nuclear Information System (INIS)

    Phosphorylation of permeabilized erythrocyte ghost membranes with ATP results in an increase free calcium level as measured with the help of Ca2+ electrode and 45Ca. This effect could not be observed in the presence of p- chloromercuric benzoate, an inhibitor of kinases. The rise in the free calcium due to phosphorylation of the membrane was accompanied by a decrease in the level of phosphatidylinositol (PI) and an increase in phosphatidylinositolmonophosphate (PIP) and phosphatidylinositolbisphosphate (PIP2). These results support the proposal that an inositol shuttle, PI ↔ PIP ↔ PIP2, operates to maintain the intracellular calcium concentration. The cation is believed to be sequestered in a cage formed by the head groups of two acidic phospholipid molecules, e.g., phosphatidylserine and phosphatidylinositol, with the participation of both PO and fatty acid ester CO groups. When the inositol group of such a cage is phosphorylated, inter-headgroup hydrogen bonding between the lipids is broken. As a result the cage opens and calcium is released

  11. Dietary factors affecting calcium and zinc absorption

    Science.gov (United States)

    Rickets is common in Nigerian children and responds better to calcium (Ca) than to vitamin D supplementation. We reported in previous studies in which oral isotopes were given with maize pap that Ca intakes are similarly low and Ca absorption (abs) similarly high in rachitic and non-rachitic Nigeria...

  12. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    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...

  13. The Thermal Decomposition of Calcium Carbonate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The thermogravimetry(TG) and derivative thermogravimetry(DTG) curves of the thermal decomposition reaction of calcium carbonate have been measured at five different heating rates. The kinetic parameters and the reaction mechanism of the reaction were evaluated from analysis of the TG and DTG curves by using the Ozawa method, the combined integral and differential methods and the reduced equations derived by us.

  14. The rate of calcium turnover in bone

    International Nuclear Information System (INIS)

    This paper reports an analysis of the clearance of calcium-47 tracer from the plasma of human patients. Nine subjects have so far been analysed, and the results all deviate somewhat from those predicted from the conventional simple kinetic scheme. 3 figs

  15. 21 CFR 184.1205 - Calcium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium hydroxide. 184.1205 Section 184.1205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  16. Three-dimensionally Perforated Calcium Phosphate Ceramics

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores380-400μm in diameter spaced at intervals of 200μm. The layers of the linear penetration pores alternately lay perpendicular to pore direction. The porosity was 59%-65% . The Ca/P molar ratios of the porous calcium phosphate ceramics range from 1.5 to 1.85. A binder containing methyl cellulose was most effective for preparing the powder compact among vinyl acetate, polyvinyl alcohol, starch, stearic acid, methyl cellulose and their mixtures. Stainless steel, polystyrene, nylon and bamboo were used as the long columnar male dies for the penetrated open pores. When polystyrene, nylon and bamboo were used as the long columnar male dies, the dies were burned out during the sintering process. Using stainless steel as the male dies with the removal of the dies before heat treatment resulted in a higher level of densification of the calcium phosphate ceramic.

  17. Dissolution kinetics of calcium phosphate coatings.

    Science.gov (United States)

    Burke, E M; Lucas, L C

    1998-01-01

    Plasma spray and high velocity oxy-fuel (HVOF) techniques produce coatings with varying composition and amounts of amorphous and crystalline phases. For coatings containing greater amorphous phases, a higher release of calcium ions is evident when samples are placed in Hank's calcium-free balanced salt solutions. Calcium is released from the amorphous phases in the coating, a conclusion that is supported by x-ray powder diffraction (XRD) results. Ion beam sputtering and RF magnetron sputtering under lower energy conditions produce amorphous coatings that will dissolve in a very short time period. When heat treated, crystalline phases are produced in the coatings. Heat-treated coatings are significantly more stable than the amorphous coatings. The dissolution rates of both amorphous and crystalline coatings produced by RF magnetron sputtering have been measured under constant solution conditions at pH 6.50. No reprecipitation is possible under these conditions. The amorphous coating dissolved at a significantly higher rate than the heat-treated coating. Reprecipitation of calcium phosphate onto amorphous coatings is possible in a physiological pH solution. Under these conditions, the dissolution rate of the amorphous coating is four times slower than at the pH 6.50 conditions. PMID:10196809

  18. Ion beam deposition of calcium hydroxyapatite

    International Nuclear Information System (INIS)

    Calcium hydroxyapatite has been sputtered on glass and Ti-6Al-4V substrates using a 1.5 kV argon ion beam. The films have been examined by X- ray diffraction analysis, energy dispersive spectroscopy, scanning electron microscopy, and adhesion testing. Results of this experimentation are presented

  19. 21 CFR 184.1195 - Calcium citrate.

    Science.gov (United States)

    2010-04-01

    ... Food Chemicals Codex, 3d ed. (1981), pp. 49 and 50, which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available from the National Academy Press, 2101... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium citrate. 184.1195 Section 184.1195 Food...

  20. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... process”. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 46... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium carbonate. 184.1191 Section 184.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  1. 21 CFR 184.1229 - Calcium stearate.

    Science.gov (United States)

    2010-04-01

    ... ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 64, which is incorporated... Codex are available from the National Academy Press, 2101 Constitution Ave. NW., Washington, DC 20418... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium stearate. 184.1229 Section 184.1229...

  2. 21 CFR 184.1210 - Calcium oxide.

    Science.gov (United States)

    2010-04-01

    ... specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 55, which is incorporated by reference. Copies are... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium oxide. 184.1210 Section 184.1210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR...

  3. Glass forming ability of calcium aluminosilicate melts

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Yue, Yuanzheng

    2011-01-01

    The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite-wollastonite-tridymite and that of...

  4. Calcium-Fosfat-Osteopontin-Partikler til Carieskontrol

    DEFF Research Database (Denmark)

    Schlafer, Sebastian

    2014-01-01

    mikroflora og påvirker den mikrobielle ligevægt i mundhulen. Calcium-fosfat-osteopontin-partikler repræsenterer en ny form for cariesprofylakse. Partiklerne, som har nanometer- og mikrometerstørrelse, er allerede afprøvet på biofilm i laboratoriet, hvor de knytter sig tæt til biofilmen uden at have en...

  5. Calcium, magnesium, and potassium in food

    Science.gov (United States)

    The biochemical and physiological functions and consequences of deficient intakes, which show the nutritional importance of calcium, magnesium and potassium for humans, are reviewed. The dietary recommendations and food sources for these essential mineral elements for humans are presented. Factors t...

  6. 21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

    Science.gov (United States)

    2010-04-01

    ... FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate... (racemic) form. (b) To assure safe use of the additive, the label and labeling of the food...

  7. Calcium Channels are Involved in Calcium Oxalate Crystal Formation in Specialized Cells of Pistia stratiotes L.

    OpenAIRE

    VOLK, GAYLE M.; GOSS, LENORA J.; FRANCESCHI, VINCENT R.

    2004-01-01

    • Background and Aims Pistia stratiotes produces large amounts of calcium (Ca) oxalate crystals in specialized cells called crystal idioblasts. The potential involvement of Ca2+ channels in Ca oxalate crystal formation by crystal idioblasts was investigated.

  8. Changes in serum calcium, magnesium and inorganic phosphorus levels during different phases of the menstrual cycle

    OpenAIRE

    Puja Dullo; Neeraj Vedi

    2008-01-01

    Background: The menstrual cycle is a complex process involving the interaction of the hypothalamus, the anterior pituitary, the ovaries and the uterus. The hormonal changes occurring during this cyclic process not only affect oocyte maturation and the endometrial and vaginal environments but can also have an effect on a number of other physiological and biochemical phenomena. Aim and Method: We investigated the changes in serum calcium, magnesium and inorganic phosphorus levels during di...

  9. Calcium influx is sufficient to induce muscular dystrophy through a TRPC-dependent mechanism

    OpenAIRE

    Millay, Douglas P.; Goonasekera, Sanjeewa A.; Sargent, Michelle A.; Maillet, Marjorie; Aronow, Bruce J; Molkentin, Jeffery D.

    2009-01-01

    Muscular dystrophy is a general term encompassing muscle disorders that cause weakness and wasting, typically leading to premature death. Membrane instability, as a result of a genetic disruption within the dystrophin-glycoprotein complex (DGC), is thought to induce myofiber degeneration, although the downstream mechanism whereby membrane fragility leads to disease remains controversial. One potential mechanism that has yet to be definitively proven in vivo is that unregulated calcium influx ...

  10. 137Cs sorption onto Fullers' Earth (calcium montmorillonite) -the influence of sulphate reducing bacteria

    International Nuclear Information System (INIS)

    The influences of Desulfovibrio desulfuricans on the sorption of 137Cs onto Fullers' Earth (Calcium montmorillonite) has been studied using batch sorption methods. Results were expressed as distributions ratios (Rd) and as Freundlich and Dubinin-Radushkevich isotherms. They show that microbes present naturally in the Fullers' Earth did not influence sorption data, however the addition of microbes in the aqueous phase alters the sorption properties in a complex manner. (author)

  11. Calcium Response in Osteocytic Networks under Steady and Oscillatory Fluid Flow

    OpenAIRE

    Lu, X. Lucas; Huo, Bo; Park, Miri; Guo, X. Edward

    2012-01-01

    The fluid flow in the lacunar-canalicular system of bone is an essential mechanical stimulation on the osteocyte networks. Due to the complexity of human physical activities, the fluid shear stress on osteocyte bodies and processes consists of both steady and oscillatory components. In this study, we investigated and compared the intracellular calcium ([Ca2+]i) responses of osteocytic networks under steady and oscillatory fluid flows. An in vitro osteocytic network was built with MLO-Y4 osteo...

  12. Cross-Talk between Signaling Pathways Can Generate Robust Oscillations in Calcium and cAMP

    OpenAIRE

    Siso-Nadal, Fernando; Fox, Jeffrey J.; Laporte, Stéphane A.; Hébert, Terence E.; Swain, Peter S

    2009-01-01

    Background To control and manipulate cellular signaling, we need to understand cellular strategies for information transfer, integration, and decision-making. A key feature of signal transduction is the generation of only a few intracellular messengers by many extracellular stimuli. Methodology/Principal Findings Here we model molecular cross-talk between two classic second messengers, cyclic AMP (cAMP) and calcium, and show that the dynamical complexity of the response of both messengers inc...

  13. Bucolic Complexes

    CERN Document Server

    Brešar, Bostjan; Chepoi, Victor; Gologranc, Tanja; Osajda, Damian

    2012-01-01

    In this article, we introduce and investigate bucolic complexes, a common generalization of systolic complexes and of CAT(0) cubical complexes. This class of complexes is closed under Cartesian products and amalgamations over some convex subcomplexes. We study various approaches to bucolic complexes: from graph-theoretic and topological viewpoints, as well as from the point of view of geometric group theory. Bucolic complexes can be defined as locally-finite simply connected prism complexes satisfying some local combinatorial conditions. We show that bucolic complexes are contractible, and satisfy some nonpositive-curvature-like properties. In particular, we prove a version of the Cartan-Hadamard theorem, the fixed point theorem for finite group actions, and establish some results on groups acting geometrically on such complexes. We also characterize the 1-skeletons (which we call bucolic graphs) and the 2-skeletons of bucolic complexes. In particular, we prove that bucolic graphs are precisely retracts of Ca...

  14. 21 CFR 182.6215 - Monobasic calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Monobasic calcium phosphate. 182.6215 Section 182.6215 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  15. 21 CFR 582.6215 - Monobasic calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Monobasic calcium phosphate. 582.6215 Section 582.6215 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  16. Mortar and concrete based on calcium sulphate binders

    NARCIS (Netherlands)

    Bakker, J.J.F.; Brouwers, H.J.H.

    2006-01-01

    In this study both hemi-hydrate and anhydrite are tested as calcium sulphate binders for structural mortar and concrete. The advantage of using calcium sulphates instead of cement as a binder is the fact that the production of calcium sulphate is more environmental friendly than that of cement. For

  17. Transfected parvalbumin alters calcium homeostasis in teratocarcinoma PCC7 cells

    DEFF Research Database (Denmark)

    Müller, B K; Kabos, P; Belhage, B;

    1996-01-01

    transfected. Parvalbumin-transfected and mock-transfected cells were loaded with the calcium indicator fura-2 and were exposed, in the same dish, to different concentrations of the calcium ionophore A23187 or to KCI. The results show that parvalbumin-transfected PCC7 cells had much better calcium buffering...

  18. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Calcium hydroxide cavity liner. 872.3250 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner. (a) Identification. A calcium hydroxide cavity liner is a device material intended to be applied to the interior of...

  19. 21 CFR 182.2122 - Aluminum calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  20. 21 CFR 582.2122 - Aluminum calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  1. Transfected parvalbumin alters calcium homeostasis in teratocarcinoma PCC7 cells

    DEFF Research Database (Denmark)

    Müller, B K; Kabos, P; Belhage, B;

    1996-01-01

    Indirect evidence supports a protective role of some EF-hand calcium-binding proteins against calcium-induced neurotoxicity. Little is known about how these proteins influence cytosolic calcium levels. After cloning the parvalbumin cDNA into an expression vector, teratocarcinoma cells (PCC7) were...

  2. Hardening of calcium hydroxide and calcium silicate binders due to carbonation and hydration

    OpenAIRE

    Cizer, Özlem; Campforts, J; Balen, Koenraad Van; Elsen, Jan; Gemert, Dionys van

    2006-01-01

    Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pr...

  3. Influence of the calcium sulfate source on the rheological behaviour of calcium sulfoaluminate cement pastes

    OpenAIRE

    Santacruz, Isabel; García-Maté, Marta; G. Aranda, Miguel Ángel; De la Torre, Ángeles G.

    2013-01-01

    Calcium sulfoaluminate (CSA) cements are receiving increasing attention since their manufacture produces much less CO2 than ordinary Portland cement (OPC) [1]. In addition, they show interesting properties such as high early-age strengths, short setting times and impermeability. The main uses of these CSA cements are for quick repairs and pre-cast products or floor concrete applications. They are prepared by mixing the clinker with different amounts of a calcium sulfate set regulator such as ...

  4. A comparative study of calcium absorption following a single serving administration of calcium carbonate powder versus calcium citrate tablets in healthy premenopausal women

    Directory of Open Access Journals (Sweden)

    Haiyuan Wang

    2014-04-01

    Full Text Available Background: Calcium is an essential mineral often taken as a daily, long-term nutritional supplement. Data suggests that once-daily dosing is important with regard to long-term compliance of both drugs and nutritional supplements. Objective: This study was undertaken to compare the bioavailability of a single serving of two calcium supplements in healthy, premenopausal women. Design: A two-period, crossover bioavailability study of a single serving of calcium citrate tablets (two tablets=500 mg calcium versus a single serving of calcium carbonate powder (one packet of powder=1,000 mg calcium was performed in healthy women aged between 25 and 45. All subjects were on a calcium-restricted diet 7 days prior to testing and fasted for 12 h before being evaluated at 0, 1, 2, and 4 h after oral administration of the test agents. Blood measurements for total and ionized calcium and parathyroid hormone were performed and adverse events were monitored. Results: Twenty-three women were evaluable with a mean age of 33.2±8.71. Results showed that administration of a single serving of a calcium carbonate powder resulted in greater absorption in total and ionized calcium versus a single serving of calcium citrate tablets at 4 h (4.25±0.21 vs. 4.16±0.16, p=0.001. There were minimal side effects and no reported serious adverse events. Conclusions: This study shows that a single serving of a calcium carbonate powder is more bioavailable than a single serving of calcium citrate tablets. This may be beneficial for long-term compliance.

  5. Calcium homeostasis in low and high calcium water acclimatized Oreochromis mossambicus exposed to ambient and dietary cadmium

    NARCIS (Netherlands)

    Pratap, H.B.; Wendelaar Bonga, S.E.

    2007-01-01

    The effects of cadmium administered via ambient water (10 mg/l) or food (10 mgCd/fish/day) on plasma calcium, corpuscles of Stannius and bony tissues of Oreochromis mossambicus acclimated to low calcium (0.2 mM) and high calcium (0.8 mM) water were studied for 2, 4, 14 and 35 days. In low calcium wa

  6. Effect of three different calcium hydroxide mixtures (calcium hydroxide with glycerine, normal saline and distilled water) on root dentin microhardness

    OpenAIRE

    Hasheminia SM; Norouzynasab S

    2007-01-01

    Background and Aim: During root canal therapy, it is necessary to remove as many bacteria as possible from the root canal. The use of medicaments is recommended to reduce the microbial population prior to root filling. Calcium hydroxide pastes have been used because of their antibacterial effects and the ability of tissue dissolving. The aim of this study was to evaluate the effect of calcium hydroxide/glycerine mixture, calcium hydroxide/normal saline mixture and calcium hydroxide/distilled ...

  7. In vivo calcium imaging of evoked calcium waves in the embryonic cortex

    Directory of Open Access Journals (Sweden)

    Mikhail eYuryev

    2016-01-01

    Full Text Available The dynamics of intracellular calcium fluxes are instrumental in the proliferation, differentiation and migration of neuronal cells. Knowledge thus far of the relationship between these calcium changes and physiological processes in the developing brain has derived principally from ex vivo and in vitro experiments. Here, we present a new method to image intracellular calcium flux in the cerebral cortex of live rodent embryos, whilst attached to the dam through the umbilical cord. Using this approach we demonstrate induction of calcium waves by laser stimulation. These waves are sensitive to ATP-receptor blockade and are significantly increased by pharmacological facilitation of intracellular-calcium release. This approach is the closest to physiological conditions yet achieved for imaging of calcium in the embryonic brain and as such opens new avenues for the study of prenatal brain development. Furthermore, the developed method could open the possibilities of preclinical translational studies in embryos particularly important for developmentally related diseases such as schizophrenia and autism.

  8. Calcium signaling and T-type calcium channels in cancer cell cycling

    Institute of Scientific and Technical Information of China (English)

    James T Taylor; Xiang-Bin Zeng; Jonathan E Pottle; Kevin Lee; Alun R Wang; Stephenie G Yi; Jennifer A S Scruggs; Suresh S Sikka; Ming Li

    2008-01-01

    Regulation of intracellular calcium is an important signaling mechanism for cell proliferation in both normal and cancerous cells. In normal epithelial cells,free calcium concentration is essential for cells to enter and accomplish the S phase and the M phase of the cell cycle. In contrast, cancerous cells can pass these phases of the cell cycle with much lower cytoplasmic free calcium concentrations, indicating an alternative mechanism has developed for fulfilling the intracellular calcium requirement for an increased rate of DNA synthesis and mitosis of fast replicating cancerous cells. The detailed mechanism underlying the altered calcium loading pathway remains unclear;however, there is a growing body of evidence that suggests the T-type Ca2+ channel is abnormally expressed in cancerous cells and that blockade of these channels may reduce cell proliferation in addition to inducing apoptosis. Recent studies also show that the expression of T-type Ca2+ channels in breast cancer cells is proliferation state dependent, i.e. the channels are expressed at higher levels during the fast-replication period, and once the cells are in a non-proliferation state, expression of this channel isminimal. Therefore, selectively blocking calcium entry into cancerous cells may be a valuable approach for preventing tumor growth. Since T-type Ca2+ channels are not expressed in epithelial cells, selective T-type Ca2+ channel blockers may be useful in the treatment of certain types of cancers.

  9. Cross-talk between signaling pathways can generate robust oscillations in calcium and cAMP.

    Directory of Open Access Journals (Sweden)

    Fernando Siso-Nadal

    Full Text Available BACKGROUND: To control and manipulate cellular signaling, we need to understand cellular strategies for information transfer, integration, and decision-making. A key feature of signal transduction is the generation of only a few intracellular messengers by many extracellular stimuli. METHODOLOGY/PRINCIPAL FINDINGS: Here we model molecular cross-talk between two classic second messengers, cyclic AMP (cAMP and calcium, and show that the dynamical complexity of the response of both messengers increases substantially through their interaction. In our model of a non-excitable cell, both cAMP and calcium concentrations can oscillate. If mutually inhibitory, cross-talk between the two second messengers can increase the range of agonist concentrations for which oscillations occur. If mutually activating, cross-talk decreases the oscillation range, but can generate 'bursting' oscillations of calcium and may enable better filtering of noise. CONCLUSION: We postulate that this increased dynamical complexity allows the cell to encode more information, particularly if both second messengers encode signals. In their native environments, it is unlikely that cells are exposed to one stimulus at a time, and cross-talk may help generate sufficiently complex responses to allow the cell to discriminate between different combinations and concentrations of extracellular agonists.

  10. Effects of modulation of calcium levels and calcium fluxes on ABA- induced gene expression in barley aleurone

    NARCIS (Netherlands)

    Meulen, R.M. van der; Visser, K.; Wang, M.

    1996-01-01

    We present data to elucidate the involvement of calcium ions in abscisic acid (ABA)-induced gene expression. Modulation of external calcium concentrations was able to affect ABA-induced specific RAB gene expression. At a constant ABA level with increasing extracellular calcium level, an increasing R

  11. Sorption behavior of Zn(II) ions on synthetic apatitic calcium phosphates

    Science.gov (United States)

    Sebei, Haroun; Pham Minh, Doan; Nzihou, Ange; Sharrock, Patrick

    2015-12-01

    The synthesis, characterization and the reactivity of apatitic calcium phosphates (Ca-HA, chemical formula Ca10(PO4)6(OH)2) is reported. Calcium carbonate (CaCO3) and potassium dihydrogen orthophosphate (KH2PO4) were selected as economical starting materials for the synthesis of Ca-HA under atmospheric conditions. Monocalcium phosphate monohydrate (MCPM), dicalcium phosphate dihydrate (DCPD), and octacalcium phosphate pentahydrate (OCP) were identified as the main intermediates of the synthesis reaction. The product obtained after 48 h of reaction contains mainly low-crystalline Ca-HA and small amounts of other calcium phosphates such as octacalcium phosphate (OCP), B-type carbonate apatite (CAP), as well as unreacted calcium carbonate. This Ca-HA was found to be active for the removal of Zn2+ from an aqueous solution. Its sorption capacity reached up to 120 mg of Zn2+ per g of Ca-HA powder after 24 h of reaction. The monitoring of soluble Zn, Ca and P during the sorption experiment allowed characterizing the mechanism of Zn uptake. Dissolution-precipitation, ionic exchange and surface complexation are the three main mechanisms involved in the sorption processes. The contribution of these mechanisms is discussed in detail.

  12. Beetroot-pigment-derived colorimetric sensor for detection of calcium dipicolinate in bacterial spores.

    Directory of Open Access Journals (Sweden)

    Letícia Christina Pires Gonçalves

    Full Text Available In this proof-of-concept study, we describe the use of the main red beet pigment betanin for the quantification of calcium dipicolinate in bacterial spores, including Bacillus anthracis. In the presence of europium(III ions, betanin is converted to a water-soluble, non-luminescent orange 1∶1 complex with a stability constant of 1.4 × 10(5 L mol(-1. The addition of calcium dipicolinate, largely found in bacterial spores, changes the color of the aqueous solution of [Eu(Bn(+] from orange to magenta. The limit of detection (LOD of calcium dipicolinate is around 2.0 × 10(-6 mol L(-1 and the LOD determined for both spores, B. cereus and B. anthracis, is (1.1 ± 0.3× 10(6 spores mL(-1. This simple, green, fast and low cost colorimetric assay was selective for calcium dipicolinate when compared to several analogous compounds. The importance of this work relies on the potential use of betalains, raw natural pigments, as colorimetric sensors for biological applications.

  13. Beetroot-pigment-derived colorimetric sensor for detection of calcium dipicolinate in bacterial spores.

    Science.gov (United States)

    Gonçalves, Letícia Christina Pires; Da Silva, Sandra Maria; DeRose, Paul C; Ando, Rômulo Augusto; Bastos, Erick Leite

    2013-01-01

    In this proof-of-concept study, we describe the use of the main red beet pigment betanin for the quantification of calcium dipicolinate in bacterial spores, including Bacillus anthracis. In the presence of europium(III) ions, betanin is converted to a water-soluble, non-luminescent orange 1∶1 complex with a stability constant of 1.4 × 10(5) L mol(-1). The addition of calcium dipicolinate, largely found in bacterial spores, changes the color of the aqueous solution of [Eu(Bn)(+)] from orange to magenta. The limit of detection (LOD) of calcium dipicolinate is around 2.0 × 10(-6) mol L(-1) and the LOD determined for both spores, B. cereus and B. anthracis, is (1.1 ± 0.3)× 10(6) spores mL(-1). This simple, green, fast and low cost colorimetric assay was selective for calcium dipicolinate when compared to several analogous compounds. The importance of this work relies on the potential use of betalains, raw natural pigments, as colorimetric sensors for biological applications. PMID:24019934

  14. RNA-induced silencing attenuates G protein-mediated calcium signals.

    Science.gov (United States)

    Philip, Finly; Sahu, Shriya; Golebiewska, Urszula; Scarlata, Suzanne

    2016-05-01

    Phospholipase Cβ (PLCβ) is activated by G protein subunits in response to environmental stimuli to increase intracellular calcium. In cells, a significant portion of PLCβ is cytosolic, where it binds a protein complex required for efficient RNA-induced silencing called C3PO (component 3 promoter of RISC). Binding between C3PO and PLCβ raises the possibility that RNA silencing activity can affect the ability of PLCβ to mediate calcium signals. By use of human and rat neuronal cell lines (SK-N-SH and PC12), we show that overexpression of one of the main components of C3PO diminishes Ca(2+) release in response to Gαq/PLCβ stimulation by 30 to 40%. In untransfected SK-N-SH or PC12 cells, the introduction of siRNA(GAPDH) [small interfering RNA(glyceraldehyde 3-phosphate dehydrogenase)] reduces PLCβ-mediated calcium signals by ∼30%, but addition of siRNA(Hsp90) (heat shock protein 90) had little effect. Fluorescence imaging studies suggest an increase in PLCβ-C3PO association in cells treated with siRNA(GAPDH) but not siRNA(Hsp90). Taken together, our studies raise the possibility that Ca(2+) responses to extracellular stimuli can be modulated by components of the RNA silencing machinery.-Philip, F., Sahu, S., Golebiewska, U., Scarlata, S. RNA-induced silencing attenuates G protein-mediated calcium signals. PMID:26862135

  15. Molecular basis of inherited calcium Channelopathies: role of mutations in pore-forming subunits

    Institute of Scientific and Technical Information of China (English)

    Lynn MCKEOWN; Philip ROBINSON; Owen T JONES

    2006-01-01

    The pore-forming alpha subunits of voltage-gated calcium channels contain the essential biophysical machinery that underlies calcium influx in response to cell depolarization.In combination with requisite auxiliary subunits,these pore subunits form calcium channel complexes that are pivotal to the physiology and pharmacology of diverse cells ranging from sperm to neurons.Not surprisingly,mutations in the pore subunits generate diverse pathologies,termed channelopathies,that range from failures in excitation-contraction coupling to night blindness.Over the last decade, major insights into the mechanisms of pathogenesis have been derived from animals showing spontaneous or induced mutations.In parallel,there has been considerable growth in our understanding of the workings of voltage-gated ion channels from a structure-function,regulation and cell biology perspective.Here we document our current understanding of the mutations underlying channelopathies involving the voltage-gated calcium channel alpha subunits in humans and other species.

  16. Calcium-Mediated Abiotic Stress Signaling in Roots.

    Science.gov (United States)

    Wilkins, Katie A; Matthus, Elsa; Swarbreck, Stéphanie M; Davies, Julia M

    2016-01-01

    Roots are subjected to a range of abiotic stresses as they forage for water and nutrients. Cytosolic free calcium is a common second messenger in the signaling of abiotic stress. In addition, roots take up calcium both as a nutrient and to stimulate exocytosis in growth. For calcium to fulfill its multiple roles must require strict spatio-temporal regulation of its uptake and efflux across the plasma membrane, its buffering in the cytosol and its sequestration or release from internal stores. This prompts the question of how specificity of signaling output can be achieved against the background of calcium's other uses. Threats to agriculture such as salinity, water availability and hypoxia are signaled through calcium. Nutrient deficiency is also emerging as a stress that is signaled through cytosolic free calcium, with progress in potassium, nitrate and boron deficiency signaling now being made. Heavy metals have the capacity to trigger or modulate root calcium signaling depending on their dose and their capacity to catalyze production of hydroxyl radicals. Mechanical stress and cold stress can both trigger an increase in root cytosolic free calcium, with the possibility of membrane deformation playing a part in initiating the calcium signal. This review addresses progress in identifying the calcium transporting proteins (particularly channels such as annexins and cyclic nucleotide-gated channels) that effect stress-induced calcium increases in roots and explores links to reactive oxygen species, lipid signaling, and the unfolded protein response. PMID:27621742

  17. Consumption of calcium-fortified cereal bars to improve dietary calcium intake of healthy women: randomized controlled feasibility study.

    Directory of Open Access Journals (Sweden)

    Jennifer T Lee

    Full Text Available Calcium is an important structural component of the skeletal system. Although an adequate intake of calcium helps to maintain bone health and reduce the risk of osteoporosis, many women do not meet recommended daily intakes of calcium. Previous interventions studies designed to increase dietary intake of women have utilized primarily dairy sources of calcium or supplements. However, lactose intolerance, milk protein allergies, or food preferences may lead many women to exclude important dairy sources of dietary calcium. Therefore, we undertook a 9 week randomized crossover design trial to examine the potential benefit of including a non-dairy source of calcium in the diet of women. Following a 3 week run-in baseline period, 35 healthy women > 18 years were randomized by crossover design into either Group I or Group II. Group I added 2 calcium-fortified cereal bars daily (total of 400 mg calcium/day (intervention to their usual diet and Group II continued their usual diet (control. At the end of 3 weeks, diets were switched for another 3 weeks. Intakes of calcium and energy were estimated from 3-day diet and supplemental diaries. Wilcoxon signed-rank tests were used for within group comparisons and Mann Whitney U tests were used for between group comparisons of calcium and energy intake. Dietary calcium was significantly higher during intervention (1071 mg/d when participants consumed 2 calcium-fortified cereal bars daily than during the baseline (720 mg/d, P <0.0001 or control diets (775 mg/d, P = 0.0001 periods. Furthermore, the addition of 2 calcium-fortified cereal bars daily for the 3 week intervention did not significantly increase total energy intake or result in weight gain. In conclusion, consumption of calcium-fortified cereal bars significantly increased calcium intake of women. Further research examining the potential ability of fortified cereal bars to help maintain and improve bone health of women is warranted.ClinicalTrials.gov NCT

  18. Immobilization of calcium sulfate contained in demolition waste

    International Nuclear Information System (INIS)

    This paper presents the results of a laboratory study undertaken to examine the treatment of demolition waste containing calcium sulfate by means of calcium sulfoaluminate clinker (CSA). The quantity of CSA necessary to entirely consume calcium sulfate was determined. Using infrared spectrometry analysis and X-ray diffraction, it was shown that calcium sulfate was entirely consumed when the ratio between CSA and calcium sulfate was 4. Standard sand was polluted by 4% calcium sulfate. Two solutions were investigated: ·either global treatment of sand by CSA, ·or immobilization of calcium sulfate by CSA, followed by the introduction of this milled mixture in standard sand. Regardless of the type of treatment, swelling was almost stabilized after 28 days of immersion in water

  19. Serca1 Truncated Proteins Unable to Pump Calcium Reduce the Endoplasmic Reticulum Calcium Concentration and Induce Apoptosis

    OpenAIRE

    Chami, Mounia; Gozuacik, Devrim; Lagorce, David; Brini, Marisa; Falson, Pierre; Peaucellier, Gérard; Pinton, Paolo; Lecoeur, Hervé; Gougeon, Marie-Lyse; le Maire, Marc; Rizzuto, Rosario; Bréchot, Christian; Paterlini-Bréchot, Patrizia

    2001-01-01

    By pumping calcium from the cytosol to the ER, sarco/endoplasmic reticulum calcium ATPases (SERCAs) play a major role in the control of calcium signaling. We describe two SERCA1 splice variants (S1Ts) characterized by exon 4 and/or exon 11 splicing, encoding COOH terminally truncated proteins, having only one of the seven calcium-binding residues, and thus unable to pump calcium. As shown by semiquantitative RT-PCR, S1T transcripts are differentially expressed in several adult and fetal human...

  20. Determination of trace calcium by solid substrate-room temperature phosphorimetry

    Institute of Scientific and Technical Information of China (English)

    Jia Ming Liu; Tian Long Yang; Xiao Mei Huang; Xiu Mei Shi; Zhong Bin Shi; Hong Wu; Guo Hui Zhu; Zhi Ming Li; Cui Lian Chen

    2007-01-01

    A new method for the determination of trace calcium by solid substrate-room temperature phosphorimetry is established. It is based on the fact that chromeazurols azurol S-phenanthroline-NaCMC (CAS-phen-NaCMC) system can emit strong and stable room temperature phosphorescence (RTP) on the solid substrate in the filter paper. Ca2+ and phenanthroline can form complex ion Ca(phen)32+, which will form complex [Ca(phen)3(CAS)2] with CAS. In the result, the number of CAS molecules in each spot increased, causing sharp increase of the RTP signal of the CAS-phen-NaCMC system.

  1. Effect of carbonate and phosphate ratios on the transformation of calcium orthophosphates

    International Nuclear Information System (INIS)

    Graphical abstract: Complexes among phosphate, carbonate and calcium have been prepared via a facile hydrothermal route. The synthesized product at the low (0.15) and the high (1.8) molar ratio of PO43−/CO32− is calcium phosphate hydrate and hydroxylapatite (HAp), respectively. Molar ratios of PO43−/CO32− are effective on the reduction of carbonate activity during the crystallization of HAp. - Highlights: • Formation of different complexes from CO32−, PO43− and Ca2+ solutions at 60 °C. • Molar ratios of PO43−/CO32 cause changes in phase and size of synthesized products. • Addition of PO43 inhibited the activity of CO32− during bound with Ca2+. • The phase transformation was completed, when CO32− peaks disappeared in FTIR. • PO43−, CO32− and Ca2+ distributed heterogeneously on the surface of precipitation. - Abstract: Complexes among phosphate, carbonate and calcium have been synthesized by a designed hydrothermal method. Effects of carbonate and phosphate ratios on the transformation of calcium-orthophosphates were investigated. With X-ray diffraction measurement the synthesized product at the low (0.15) and the high (1.8) molar ratio of PO43−/CO32− is calcium phosphate hydrate at pH 9.0, and hydroxylapatite (HAp) at pH 8.0, respectively. Fourier transform infrared spectroscopy of product at the high ratio (1.8) of PO43−/CO32− shows that the CO32− peaks disappear, and the strong peaks at 1412 and 1460 cm−1 are assigned to the vibrations of PO43− in HAp. 31P nuclear magnetic resonance spectra of products at the low (0.15–0.6) to the high (1.2–1.8) ratios of PO43−/CO32− are obtained at 2.9 and 2.7 ppm, respectively. Molar ratios of PO43−/CO32− are effective on the reduction of carbonate activity during the formation and infiltration events of calcium-phosphate surface precipitates, and are subsequently enclosed during HAp formation

  2. Tropical complexes

    OpenAIRE

    Cartwright, Dustin

    2013-01-01

    We introduce tropical complexes, which are Delta-complexes together with additional numerical data. On a tropical complex, we define divisors and linear equivalence between divisors, analogous to the notions for algebraic varieties, and generalizing previous work for graphs. We prove a comparison theorem showing that divisor-curve intersection numbers agree under certain conditions.

  3. Medical Complex

    OpenAIRE

    Kumaraswamy, Mohan

    2002-01-01

    One element of the CIVCAL project Web-based resources containing images, tables, texts and associated data on the construction of the Medical Complex. This project covers the construction of a new Hong Kong University Medical Complex on Sassoon Road, Pokfulam. The complex will comprise two buildings, one will house laboratories and a car park, while the other will contain lecture halls

  4. Application of molecular calcium compounds in catalysis and hydrogen storage; Anwendung von molekularen Calcium-Verbindungen in der Katalyse und der Wasserstoffspeicherung

    Energy Technology Data Exchange (ETDEWEB)

    Spielmann, Jan

    2010-07-20

    1. Applications in catalysis: In the course of this work new catalytic applications of calcium compounds and in particular hydrocarbon-soluble calcium hydride species have been investigated. The complex [(DIPP-nacnac)CaH(THF)]2 (1, DIPP-nacnac = HC[C(Me)N-2,6-(i-Pr)-C6H3]2) served as a model system to test reactivity of the calcium hydride in stoichiometric reactions on a molecular level. It has been found that the hydroboration of conjugated alkenes with catecholborane can be accelerated considerably by using catalytic amounts of calcium complexes. However it was shown that calcium hydride species catalyze the decomposition of catecholborane to BH3 which is probably the catalytically active species. Investigations on the catalytic hydrosilylation of ketones have demonstrated that calcium complexes are efficient catalysts for this reaction. In the proposed catalytic cycle of this reaction six-coordinate hypervalent silicon species play a crucial role. Furthermore it has been shown that molecular calcium compounds are catalysts for the hydrogenation of conjugated alkenes with H2 under relatively mild conditions (20 bar H2, 20 C). Both steps in the proposed catalytical cycle i.e. addition of a metal hydride to the C=C double bond and a heterolytic cleavage of H2 by a calcium alkyl compound have been confirmed experimentally. 2. Applications in hydrogen storage: Ligand stabilized metal amidoborane complexes in the form of (DIPP-nacnac)MNH(R)BH3(THF)x (M = Ca, Mg; R = H, Me, i-Pr, 2,6-(i-Pr)-C6H3; x = 0, 1, 2) have been synthesized and structurally characterized. These complexes are model systems for the metal amidoborane compounds M(NH2BH3)n (M = Li, Na, n = 1; M = Ca, n = 2), which are potential high capacity hydrogen storage materials. To get insights in their dehydrogenation mechanisms the thermal decomposition of the model compounds was investigated in solution. This allowed for the first isolation of well-defined dehydrogenated products which have been

  5. Ceramics based on calcium pyrophosphate nanopowders

    Directory of Open Access Journals (Sweden)

    Tatiana V. Safronova

    2013-03-01

    Full Text Available Present work is aimed at the fabrication of resorbable bioceramics based on calcium pyrophosphate (CPP from the synthesized powders of amorphous hydrated calcium pyrophosphate (AHCPP. Amorphous hydratedcalcium pyrophosphate in the form of nanopowders was precipitated from Ca(NO3 2 and (NH4 4P2O7 solutions at room temperature in the presence of PO3– ions. Crystalline CPP powder was fabricated from AHCPP by its thermal decomposition at 600 °C and consisted of β- and α- phase. Small particles, with the size less than 200 nm, were formed promoting sintering of the ceramic material. The final sample, sintered at 900 °C, exhibits microstructure with submicron grains, apparent density of 87% of theoretical density (TD and demonstrates tensile strength of 70 MPa.

  6. Aggregation of Calcium Silicate Hydrate Nanoplatelets.

    Science.gov (United States)

    Delhorme, Maxime; Labbez, Christophe; Turesson, Martin; Lesniewska, Eric; Woodward, Cliff E; Jönsson, Bo

    2016-03-01

    We study the aggregation of calcium silicate hydrate nanoplatelets on a surface by means of Monte Carlo and molecular dynamics simulations at thermodynamic equilibrium. Calcium silicate hydrate (C-S-H) is the main component formed in cement and is responsible for the strength of the material. The hydrate is formed in early cement paste and grows to form platelets on the nanoscale, which aggregate either on dissolving cement particles or on auxiliary particles. The general result is that the experimentally observed variations in these dynamic processes generically called growth can be rationalized from interaction free energies, that is, from pure thermodynamic arguments. We further show that the surface charge density of the particles determines the aggregate structures formed by C-S-H and thus their growth modes. PMID:26859614

  7. Effects of Exterior Abscisic Acid on Calcium Distribution of Mesophyll Cells and Calcium Concentration of Guard Cells in Maize Seedlings

    Institute of Scientific and Technical Information of China (English)

    GUO Xiu-lin; MA Yuan-yuan; LIU Zi-hui; LIU Bin-hui

    2008-01-01

    In this study, the direct effects of exterior abscisic acid (ABA) on both calcium distribution of mesophyll cells and cytosolic calcium concentration of guard cells were examined. The distribution of Ca2+ localization were observed with calcium antimonate precipitate-electromicroscopic-cyto-chemical methods after treated with ABA and pretreated with ethylene glycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA), verapamil (Vp), and trifluoperazine (TFP). The laser scanning confocal microscopy was used to measure the cytosolic calcium concentrations of guard cells under different treatments. The results showed that the cytosolic Ca2+ concentration of mesophyll cells was induced to increase by ABA, but to decrease in both outside cell and the vacuoles within 10 min after treatments. The cytosolic calcium concentration of guard cells was increased gradually with the lag in treatment time. However, both EGTA and TFP could inverse those effects, indicating that the increase of cytosolic calcium induced by exterior ABA was mainly caused by calcium influx. The results also showed that calmodulin could influence both the calcium distribution of mesophyll cells and calcium concentration of guard cells. It shows that calmodulin participates in the process of ABA signal transduction, but the mechanism is not known as yet. The changes both calcium distribution of mesophyll cells and calcium concentration of guard cells further proved that the variations of cytosolic Ca2+ concentration induced by ABA were involved in the stomatal movements of maize seedlings.

  8. Dynamic response of porous calcium carbonate minerals

    International Nuclear Information System (INIS)

    A theoretical study of the shock-loaded response of calcium carbonate materials is presented in which both dry and water-saturated samples with porosities up to 50 percent are considered. Data are presented for the unloading response from 15.0 and 18.5 GPa, and calculations from a mixture model using a Mie-Grueneisen equation of state with volume-dependent parameters are compared to both the Hugoniot and the isentropic unloading response

  9. Coronary artery calcium scoring in myocardial infarction

    International Nuclear Information System (INIS)

    Background. The aim of this study was to evaluate coronary artery calcium scoring and the assessment of the risk factors in patients with myocardial infarction (MI). Methods. During the period of three years, 27 patients with MI were analyzed. The average age of patients was 66.1 years (46 to 81). Coronary arteries calcium was evaluated by multi row detector computed tomography (MTDC) Somatom Volume Zoom Siemens, and, retrospectively by ECG gating data acquisition. Semi automated calcium quantification to calculate Agatston calcium score (CS) was performed with 4 x 2.5 mm collimation, using 130 ml of contrast medium, injected with an automatic injector, with the flow rate of 4 ml/sec. The delay time was determined empirically. At the same time several risk factors were evaluated. Results. Out of 27 patients with MI, 3 (11.1%) patients had low CS (10- 100), 5 (18.5%) moderate CS (101- 499), and 19 (70.4%) patients high CS (>500). Of risk factors, smoking was confirmed in 17 (63.0%), high blood pressure (HTA) in 10 (57.0%), diabetes mellitus in 7 (25.9%), positive family history in 5 (18.5%), pathological lipids in 5 (18.5%), alcohol abuse in 4 (1.8%) patients. Six (22.2%) patients had symptoms of angina pectoris. Conclusions. The research showed high correlation of MI and high CS (>500). Smoking, HTA, diabetes mellitus, positive family history and hypercholesterolemia are significant risk factors. Symptoms are relatively poor in large number of patients. (author)

  10. Calcium metabolism in lithium-treated patients

    International Nuclear Information System (INIS)

    The bone mineral content (BMC) together with biochemical indices of calcium metabolism were measured in 83 manic-depressive patients on long-term lithium therapy. The patients were diagnosed and divided into a unipolar and a bipolar group according to strict symptomatic course criteria. The patients with bipolar course had a significantly decreased BMC (88% of normal, P < 0.001), while the unipolar patients had normal BMC. Both groups had biochemical changes consistent with primary hyperparathyroidism. (author)

  11. Premixed calcium silicate cement for endodontic applications

    OpenAIRE

    Persson, Cecilia; Engqvist, Håkan

    2011-01-01

    Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and am...

  12. Calcium signaling: A tale for all seasons

    OpenAIRE

    Carafoli, Ernesto

    2002-01-01

    An experiment performed in London nearly 120 years ago, which by today's standards would be considered unacceptably sloppy, marked the beginning of the calcium (Ca2+) signaling saga. Sidney Ringer [Ringer, S. (1883) J. Physiol. 4, 29–43] was studying the contraction of isolated rat hearts. In earlier experiments, Ringer had suspended them in a saline medium for which he admitted to having used London tap water, which is hard: The hearts contracted beautifully. When he proceeded to replace the...

  13. Kinetics of strontium sorption in calcium phosphate

    International Nuclear Information System (INIS)

    Kinetics of strontium sorption by highly dispersed solids: tricalcium phosphate (Ca3(PO4)2, TCP) and hydroxyapatite (Ca5(PO4)3)H, HAP) were investigated. Analysis of sorption data was made taking into consideration composition and morphology of ultra micro particles. Conclusion is that the isomorphous strontium impurity is structurally sensitive element for calcium phosphate. It was determined that the beginning of strontium desorption corresponds to the beginning of transformation of the TCP - HAP (author)

  14. 21 CFR 184.1201 - Calcium glycerophosphate.

    Science.gov (United States)

    2010-04-01

    ... ingredient meets the specifications of the “Food Chemicals Codex,” 3d Ed. (1981), pp. 51-52, which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium glycerophosphate. 184.1201 Section...

  15. Biomimetic mineralization: encapsulation in calcium carbonate shells

    OpenAIRE

    Oliveira, Susana Costa de

    2015-01-01

    Calcium carbonate biomineralization is a self-assembly process that has been studied to be applied in the biomedical field to encapsulate biomolecules. Advantages of engineering mineral capsules include improved drug loading efficiencies and protection against external environment. However, common production methods result in heterogeneous capsules and subject biomolecules to heat and vibration which cause irreversible damage. To overcome these issues, a microfluidic device was designed, m...

  16. Effect of dairy calcium or supplementary calcium intake on postprandial fat metabolism, appetite, and subsequent energy intake

    DEFF Research Database (Denmark)

    Lorenzen, J.K.; Nielsen, S.; Holst, J.J.; Tetens, Inge; Rehfeld, J.F.; Astrup, A.

    2007-01-01

    were tested in 18 subjects according to a randomized crossover design. The test meals contained high (HC meal: 172 mg/MJ), medium (MC meal: 84 mg/MJ), or low (LC meal: 15 mg/MJ) amounts of calcium from dairy products or a high amount of calcium given as a calcium carbonate supplement (Suppl meal: 183......, glucagon-like peptide 1, ghrelin, peptide YY, insulin, or glucose were observed. Conclusions: Increased calcium intakes from dairy products attenuate postprandial lipidemia, most probably because of reduced fat absorption, whereas supplementary calcium carbonate does not exert such an effect. This may be......Background: High calcium intake has been shown to increase fecal fat excretion. Objective: Our aim was to examine whether a high calcium intake from dairy products or from supplements affects postprandial fat metabolism and appetite through fat malabsorption. Design: Four different isocaloric meals...

  17. Recording of calcium transient and analysis of calcium removal mechanisms in cardiac myocytes from rats and ground squirrels

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With confocal microscopy, we recorded calcium transients and analyzed calcium removal rate at different temperatures in cardiac myocytes from the rat, a non-hibernator, and the ground squirrel, a hibernator. The results showed a remarkable increase of the diastolic level of calcium transients in the rat but no detectable change in the ground squirrel. Calcium transient of the ground squirrel, compared with that of the rat at the same temperature, had a shorter duration and showed a faster calcium removal. As indicated by the pharmacological effect of cyclopiazonic acid, calcium uptake by sarcoplasmic reticulum (SR) was the major mechanism of calcium removal, and was faster in the ground squirrel than in the rat. Our results confirmed the essential role of SR in hypothermia-tolerant adaptation, and negated the importance of Na-Ca exchange. We postulated the possibility to improve hypothermia-tolerance of the cardiac tissue of non-hibernating mammals.

  18. Communication complexity and information complexity

    Science.gov (United States)

    Pankratov, Denis

    Information complexity enables the use of information-theoretic tools in communication complexity theory. Prior to the results presented in this thesis, information complexity was mainly used for proving lower bounds and direct-sum theorems in the setting of communication complexity. We present three results that demonstrate new connections between information complexity and communication complexity. In the first contribution we thoroughly study the information complexity of the smallest nontrivial two-party function: the AND function. While computing the communication complexity of AND is trivial, computing its exact information complexity presents a major technical challenge. In overcoming this challenge, we reveal that information complexity gives rise to rich geometrical structures. Our analysis of information complexity relies on new analytic techniques and new characterizations of communication protocols. We also uncover a connection of information complexity to the theory of elliptic partial differential equations. Once we compute the exact information complexity of AND, we can compute exact communication complexity of several related functions on n-bit inputs with some additional technical work. Previous combinatorial and algebraic techniques could only prove bounds of the form theta( n). Interestingly, this level of precision is typical in the area of information theory, so our result demonstrates that this meta-property of precise bounds carries over to information complexity and in certain cases even to communication complexity. Our result does not only strengthen the lower bound on communication complexity of disjointness by making it more exact, but it also shows that information complexity provides the exact upper bound on communication complexity. In fact, this result is more general and applies to a whole class of communication problems. In the second contribution, we use self-reduction methods to prove strong lower bounds on the information

  19. 3D Computational Simulation of Calcium Leaching in Cement Matrices

    Directory of Open Access Journals (Sweden)

    Gaitero, J. J.

    2014-12-01

    Full Text Available Calcium leaching is a degradation process consisting in progressive dissolution of the cement paste by migration of calcium atoms to the aggressive solution. It is therefore, a complex phenomenon involving several phases and dissolution and diffusion processes simultaneously. Along this work, a new computational scheme for the simulation of the degradation process in three dimensions was developed and tested. The toolkit was used to simulate accelerated calcium leaching by a 6M ammonium nitrate solution in cement matrices. The obtained outputs were the three dimensional representation of the matrix and the physicochemical properties of individual phases as a consequence of the degradation process. This not only makes it possible to study the evolution of such properties as a function of time but also as a function of the position within the matrix. The obtained results are in good agreement with experimental values of the elastic modulus in degraded and undegraded samples.El lixiviado de calcio es un proceso de degradación consistente en la disolución progresiva de la pasta de cemento por la migración de los átomos de calcio a la disolución agresiva. Se trata por tanto de un fenómeno complejo que involucra simultáneamente diferentes fases y procesos de disolución y difusión. En este trabajo se desarrolló y probó una nueva herramienta computacional para la simulación del proceso de degradación en tres dimensiones. Para ello se simuló el lixiviado de calcio acelerado provocado por una disolución de nitrato amónico 6M en matrices de cemento. Como resultado se obtuvieron la representación tridimensional de la matriz y las propiedades físico-químicas sus fases a lo largo del tiempo. Esto permitió estudiar la evolución de dichas propiedades a lo largo del proceso de degradación así como en función de su posición dentro de la matriz. Los resultados obtenidos coinciden con los valores experimentales del módulo elástico tanto

  20. Calcium and ROS: A mutual interplay.

    Science.gov (United States)

    Görlach, Agnes; Bertram, Katharina; Hudecova, Sona; Krizanova, Olga

    2015-12-01

    Calcium is an important second messenger involved in intra- and extracellular signaling cascades and plays an essential role in cell life and death decisions. The Ca(2+) signaling network works in many different ways to regulate cellular processes that function over a wide dynamic range due to the action of buffers, pumps and exchangers on the plasma membrane as well as in internal stores. Calcium signaling pathways interact with other cellular signaling systems such as reactive oxygen species (ROS). Although initially considered to be potentially detrimental byproducts of aerobic metabolism, it is now clear that ROS generated in sub-toxic levels by different intracellular systems act as signaling molecules involved in various cellular processes including growth and cell death. Increasing evidence suggests a mutual interplay between calcium and ROS signaling systems which seems to have important implications for fine tuning cellular signaling networks. However, dysfunction in either of the systems might affect the other system thus potentiating harmful effects which might contribute to the pathogenesis of various disorders. PMID:26296072

  1. Architecture of the mitochondrial calcium uniporter.

    Science.gov (United States)

    Oxenoid, Kirill; Dong, Ying; Cao, Chan; Cui, Tanxing; Sancak, Yasemin; Markhard, Andrew L; Grabarek, Zenon; Kong, Liangliang; Liu, Zhijun; Ouyang, Bo; Cong, Yao; Mootha, Vamsi K; Chou, James J

    2016-05-12

    Mitochondria from many eukaryotic clades take up large amounts of calcium (Ca(2+)) via an inner membrane transporter called the uniporter. Transport by the uniporter is membrane potential dependent and sensitive to ruthenium red or its derivative Ru360 (ref. 1). Electrophysiological studies have shown that the uniporter is an ion channel with remarkably high conductance and selectivity. Ca(2+) entry into mitochondria is also known to activate the tricarboxylic acid cycle and seems to be crucial for matching the production of ATP in mitochondria with its cytosolic demand. Mitochondrial calcium uniporter (MCU) is the pore-forming and Ca(2+)-conducting subunit of the uniporter holocomplex, but its primary sequence does not resemble any calcium channel studied to date. Here we report the structure of the pore domain of MCU from Caenorhabditis elegans, determined using nuclear magnetic resonance (NMR) and electron microscopy (EM). MCU is a homo-oligomer in which the second transmembrane helix forms a hydrophilic pore across the membrane. The channel assembly represents a new solution of ion channel architecture, and is stabilized by a coiled-coil motif protruding into the mitochondrial matrix. The critical DXXE motif forms the pore entrance, which features two carboxylate rings; based on the ring dimensions and functional mutagenesis, these rings appear to form the selectivity filter. To our knowledge, this is one of the largest membrane protein structures characterized by NMR, and provides a structural blueprint for understanding the function of this channel. PMID:27135929

  2. Arterial Stiffness and Dialysis Calcium Concentration

    Directory of Open Access Journals (Sweden)

    Fabrice Mac-Way

    2011-01-01

    Full Text Available Arterial stiffness is the major determinant of isolated systolic hypertension and increased pulse pressure. Aortic stiffness is also associated with increased cardiovascular morbidity and mortality in patients with chronic kidney disease, hypertension, and general population. Hemodynamically, arterial stiffness results in earlier aortic pulse wave reflection leading to increased cardiac workload and decreased myocardial perfusion. Although the clinical consequence of aortic stiffness has been clearly established, its pathophysiology in various clinical conditions still remains poorly understood. The aim of the present paper is to review the studies that have looked at the impact of dialysis calcium concentration on arterial stiffness. Overall, the results of small short-term studies suggest that higher dialysis calcium is associated with a transient but significant increase in arterial stiffness. This calcium dependant increase in arterial stiffness is potentially explained by increased vascular smooth muscle tone of the conduit arteries and is not solely explained by changes in mean blood pressure. However, the optimal DCa remains to be determined, and long term studies are required to evaluate its impact on the progression of arterial stiffness.

  3. Modeling Calcium Wave Based on Anomalous Subdiffusion of Calcium Sparks in Cardiac Myocytes

    Science.gov (United States)

    Chen, Xi; Kang, Jianhong; Fu, Ceji; Tan, Wenchang

    2013-01-01

    sparks and waves play important roles in calcium release and calcium propagation during the excitation-contraction (EC) coupling process in cardiac myocytes. Although the classical Fick’s law is widely used to model sparks and waves in cardiac myocytes, it fails to reasonably explain the full-width at half maximum(FWHM) paradox. However, the anomalous subdiffusion model successfully reproduces sparks of experimental results. In this paper, in the light of anomalous subdiffusion of sparks, we develop a mathematical model of calcium wave in cardiac myocytes by using stochastic release of release units (CRUs). Our model successfully reproduces calcium waves with physiological parameters. The results reveal how concentration waves propagate from an initial firing of one CRU at a corner or in the middle of considered region, answer how large in magnitude of an anomalous spark can induce a wave. With physiological currents (2pA) through CRUs, it is shown that an initial firing of four adjacent CRUs can form a wave. Furthermore, the phenomenon of calcium waves collision is also investigated. PMID:23483894

  4. Raman spectroscopic studies of chemical speciation in calcium chloride melts

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Lavender, Curt A.

    2005-02-01

    Raman spectroscopy was applied to CaCl2 melts at 900 degrees C under both non-electrolyzed and electrolyzed conditions. The later used titania cathodes supplied by TIMET, Inc. and graphite anodes. Use of pulse-gating to collect the Raman spectra successfully eliminated any interference from black-body radiation and other stray light. The spectrum of molten CaCl2 exhibited no distinct, resolvable bands that could be correlated with a calcium chloride complex similar to MgCl42- in MgCl2 melts. Rather, the low frequency region of the spectrum was dominated by a broad “tail” arising from collective oscillations of both charge and mass in the molten salt “network.” Additions of both CaO and Ca at concentrations of a percent or two resulted in no new features in the spectra. Addition of CO2, both chemically and via electrolysis at concentrations dictated by stability and solubility at 900 degrees C and 1 bar pressure, also produced no new bands that could be correlated with either dissolved CO2 or the carbonate ion. These results indicated that Raman spectroscopy, at least under the conditions evaluated in the research, was not well suited for following the reactions and coordination chemistry of calcium ions, nor species such as dissolved metallic Ca and CO2 that are suspected to impact current efficiency in titanium electrolysis cells using molten CaCl2. Raman spectra of TIMET titania electrodes were successfully obtained as a function of temperature up to 900 degrees C, both in air and in-situ in CaCl2 melts. However, spectra of these electrodes could only be obtained when the material was in the unreduced state. When reduced, either with hydrogen or within an electrolysis cell, the resulting electrodes exhibited no measurable Raman bands under the conditions used in this work.

  5. Evaluation of calcium ion, hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments: An in vitro study

    OpenAIRE

    Punit Fulzele; Sudhindra Baliga; Nilima Thosar; Debaprya Pradhan

    2011-01-01

    Aims: Evaluation of calcium ion and hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments. Objective: The purpose of this study was to evaluate calcium and hydroxyl ion release and pH levels of calcium hydroxide based products, namely, RC Cal, Metapex, calcium hydroxide with distilled water, along with the new gutta-percha points with calcium hydroxide. Materials and Methods: The materials were inserted in polyethylene tubes and immersed in deionized wat...

  6. Calcium microdomains near R-type calcium channels control the induction of presynaptic LTP at parallel fiber to Purkinje cell synapses

    OpenAIRE

    Myoga, Michael H.; Regehr, Wade G.

    2011-01-01

    R-type calcium channels in postsynaptic spines signal through functional calcium microdomains to regulate a calcium-calmodulin sensitive potassium channel that in turn regulates postsynaptic hippocampal LTP. Here we ask whether R-type calcium channels in presynaptic terminals also signal through calcium microdomains to control presynaptic LTP. We focus on presynaptic LTP at parallel fiber to Purkinje cell synapses in the cerebellum (PF-LTP), which is mediated by calcium/calmodulin-stimulated ...

  7. Dihydroxyacetone (DHA) monomer complexes with CaBr2 and CdCl2.

    Science.gov (United States)

    Rlepokura, Katarzyna; Lis, Tadeusz

    2008-03-01

    Two hydrated complexes of monomeric dihydroxyacetone (DHA; the simplest ketose), viz. the calcium bromide complex bis(mu-dihydroxyacetone)bis[tetraaquacalcium(II)] tetrabromide (isomorphous with the chloride compound reported previously), [Ca(2)(C(3)H(6)O(3))(2)(H(2)O)(8)]Br(4), (2e), and the cadmium chloride complex poly[[bis(mu-dihydroxyacetone)bis[bis(dihydroxyacetone)cadmium(II)

  8. Calcium is required for swimming by the nonflagellated cyanobacterium Synechococcus strain WH8113.

    OpenAIRE

    Pitta, T P; Sherwood, E E; Kobel, A M; Berg, H C

    1997-01-01

    The marine cyanobacterium Synechococcus strain WH8113 swims in the absence of any recognizable organelles of locomotion. We have found that calcium is required for this motility. Cells deprived of calcium stopped swimming, while addition of calcium completely restored motility. No other divalent ions tested could replace calcium. Terbium, a lanthanide ion, blocked motility even when calcium was present at 10(5)-fold-higher concentrations, presumably by occupying calcium binding sites. Calcium...

  9. A membrane model for cytosolic calcium oscillations. A study using Xenopus oocytes.

    OpenAIRE

    Jafri, M S; Vajda, S.; Pasik, P; Gillo, B.

    1992-01-01

    Cytosolic calcium oscillations occur in a wide variety of cells and are involved in different cellular functions. We describe these calcium oscillations by a mathematical model based on the putative electrophysiological properties of the endoplasmic reticulum (ER) membrane. The salient features of our membrane model are calcium-dependent calcium channels and calcium pumps in the ER membrane, constant entry of calcium into the cytosol, calcium dependent removal from the cytosol, and buffering ...

  10. TRPV4 and AQP4 Channels Synergistically Regulate Cell Volume and Calcium Homeostasis in Retinal Müller Glia

    DEFF Research Database (Denmark)

    Jo, Andrew O; Ryskamp, Daniel A; Phuong, Tam T T;

    2015-01-01

    facilitates the time course and amplitude of hypotonicity-induced swelling and regulatory volume decrease. We confirm the crucial facets of the signaling mechanism in heterologously expressing oocytes. These results identify the molecular mechanism that contributes to dynamic regulation of glial volume but...... Ca(2+) entry through TRPV4 channels reciprocally modulates volume regulation, swelling, and Aqp4 gene expression. Therefore, TRPV4-AQP4 interactions constitute a molecular system that fine-tunes astroglial volume regulation by integrating osmosensing, calcium signaling, and water transport and, when...... complex set of mechanisms involving reciprocal interactions at the level of glial gene expression, calcium homeostasis, swelling, and volume regulation. Specifically, water influx through AQP4 drives calcium influx via TRPV4 in the glial end foot, which regulates expression of Aqp4 and Kir4.1 genes and...

  11. The calcium oxide influence on formation of manganese, calcium pyrovanadate solid solutions

    International Nuclear Information System (INIS)

    The X-ray graphic, derivatographic, microscopic and chemical methods are used to study solid solutions of manganese, calcium pyrovanadates containing 1-10 mass% CaO and the products of interaction of reprocessing charges of vanadium-containing converter slags intended for he formation of manganese and calcium pyrovanadates with additions of calcium oxide within 10-90 mass%. It is established that in the case of 1-6 mass% CaO content in manganese pyrovanadate solid interstitial solutions appear, while at 6-20 mass% CaO - solid substitution solutions form. The results of calculating elementary cell parameters as well as melting temperatures and pyrovanadate solid solution solubility depending on CaO content are presented. The best solubility of introduction solid solutions during vanadium extraction according to the lime technology is found

  12. Synthesis of Calcium Silicate (Casio3 Using Calcium Fluoride, Quartz and Microbes

    Directory of Open Access Journals (Sweden)

    B. Gopal Krishna

    2015-09-01

    Full Text Available Microbes like bacteria, algae, fungi and virus play an important role to catalyst chemical reactions. In Nature, ores or minerals of different compounds are formed due to microbial environment and other factors like weathering. Microbial environment is also instrumental in forming calcium containing silicate minerals. Chemical reactions occur under microbial environment because microbes have the ability to control or modify different factors like pH, chemical potential and temperature during reactions. In this paper, synthesis of calcium silicate (CaSiO3 using calcium fluoride (CaF2 and quartz (SiO2 under microbial environment in a laboratory is being adopted to produce the required material. XRD technique is used to confirm the formation of CaSiO3.

  13. Overcoming Matrix Effects in a Complex Sample: Analysis of Multiple Elements in Multivitamins by Atomic Absorption Spectroscopy

    Science.gov (United States)

    Arnold, Randy J.; Arndt, Brett; Blaser, Emilia; Blosser, Chris; Caulton, Dana; Chung, Won Sog; Fiorenza, Garrett; Heath, Wyatt; Jacobs, Alex; Kahng, Eunice; Koh, Eun; Le, Thao; Mandla, Kyle; McCory, Chelsey; Newman, Laura; Pithadia, Amit; Reckelhoff, Anna; Rheinhardt, Joseph; Skljarevski, Sonja; Stuart, Jordyn; Taylor, Cassie; Thomas, Scott; Tse, Kyle; Wall, Rachel; Warkentien, Chad

    2011-01-01

    A multivitamin tablet and liquid are analyzed for the elements calcium, magnesium, iron, zinc, copper, and manganese using atomic absorption spectrometry. Linear calibration and standard addition are used for all elements except calcium, allowing for an estimate of the matrix effects encountered for this complex sample. Sample preparation using…

  14. Mathematical analysis of complex cellular activity

    CERN Document Server

    Bertram, Richard; Teka, Wondimu; Vo, Theodore; Wechselberger, Martin; Kirk, Vivien; Sneyd, James

    2015-01-01

    This book contains two review articles on mathematical physiology that deal with closely related topics but were written and can be read independently. The first article reviews the basic theory of calcium oscillations (common to almost all cell types), including spatio-temporal behaviors such as waves. The second article uses, and expands on, much of this basic theory to show how the interaction of cytosolic calcium oscillators with membrane ion channels can result in highly complex patterns of electrical spiking. Through these examples one can see clearly how multiple oscillatory processes interact within a cell, and how mathematical methods can be used to understand such interactions better. The two reviews provide excellent examples of how mathematics and physiology can learn from each other, and work jointly towards a better understanding of complex cellular processes. Review 1: Richard Bertram, Joel Tabak, Wondimu Teka, Theodore Vo, Martin Wechselberger: Geometric Singular Perturbation Analysis of Burst...

  15. Combination of Agatston Calcium Score and CTA: quantification and characterization of carotid calcium

    International Nuclear Information System (INIS)

    Objective: To quantify and characterize carotid calcification with combined Agatston Calcium Score and multidetector CT angiography (MDCTA) and to determine whether the combination could he applied as a useful decision- making tool for treatment. Methods: A total of 136 carotid arteries were examined with MDCTA (67.6±10.2 years; age range from 37-86 years; 11 women, 57 men). The calcium scores were determined using Agatston method from pre-contrast data. The stenosis was assessed based on North American Symptomatic Carotid Endarterectomy Trial criteria from post-contrast data. Results: Symptomatic patients had higher total calcium volume (TCV), total equiv mass (TEM) and total calcium score (TCS) than asymptomatic patients, but the differences did not reach statistical significance with or without taking the interactive effect of age and stenosis into account. TCV, TEM, and TCS differed significantly between high-grade and mild- grade stenotic vessels (P<0.001), and moderate-grade and mild-grade stenotic vessels (P<0.001); and they also differed statistically between age groups of 51-69 years and of ≥70 years (P<0.001). Pearson's correlation test showed a mild but significant correlation between stenotic grade of carotid bifurcation and ipsilateral ICA and total calcium volume (rbifurcation=0.322 and rICA=0.418 respectively, P<0.01). Conclusion: Combination of Agatston Calcium Score and CTA is likely to emerge as a noninvasive choice to accurately assess calcification and quantification of the burden in the carotid arteries. It can provide valuable insights into plaque characterization and stability, which is especially important for clinical decision-making. (authors)

  16. Experimental Study and Monte Carlo Modeling of Calcium Borosilicate Glasses Leaching

    International Nuclear Information System (INIS)

    During aqueous alteration of glass an alteration layer appears on the glass surface. The properties of this alteration layer are of great importance for understanding and predicting the long-term behavior of high-level radioactive waste glasses. Numerical modeling can be very useful for understanding the impact of the glass composition on its aqueous reactivity and long-term properties but it is quite difficult to model these complex glasses. In order to identify the effect of the calcium content on glass alteration, seven oxide glass compositions (57SiO2 17B2O3 (22-x)Na2OxCaO 4ZrO2; 0 < x < 11) were investigated and a Monte Carlo model was developed to describe their leaching behavior. The specimens were altered at constant temperature (T = 90 deg. C) at a glass-surface-area-to-solution-volume (SA/V) ratio of 15 cm-1 in a buffered solution (pH 9.2). Under these conditions all the variations observed in the leaching behavior are attributable to composition effects. Increasing the calcium content in the glass appears to be responsible for a sharp drop in the final leached boron fraction. In parallel with this experimental work, a Monte Carlo model was developed to investigate the effect of calcium content on the leaching behavior especially on the initial stage of alteration. Monte Carlo simulations performed with this model are in good agreement with the experimental results. The dependence of the alteration rate on the calcium content can be described by a quadratic function: fitting the simulated points gives a minimum alteration rate at about 7.7 mol% calcium. This value is consistent with the figure of 8.2 mol% obtained from the experimental work. The model was also used to investigate the role of calcium in the glass structure and it pointed out that calcium act preferentially as a network modifier rather than a charge compensator in this kind of glasses. (authors)

  17. Complexity Plots

    KAUST Repository

    Thiyagalingam, Jeyarajan

    2013-06-01

    In this paper, we present a novel visualization technique for assisting the observation and analysis of algorithmic complexity. In comparison with conventional line graphs, this new technique is not sensitive to the units of measurement, allowing multivariate data series of different physical qualities (e.g., time, space and energy) to be juxtaposed together conveniently and consistently. It supports multivariate visualization as well as uncertainty visualization. It enables users to focus on algorithm categorization by complexity classes, while reducing visual impact caused by constants and algorithmic components that are insignificant to complexity analysis. It provides an effective means for observing the algorithmic complexity of programs with a mixture of algorithms and black-box software through visualization. Through two case studies, we demonstrate the effectiveness of complexity plots in complexity analysis in research, education and application. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.

  18. The calcium-sensing receptor is required for normal calcium homeostasis independent of parathyroid hormone

    OpenAIRE

    Kos, Claudine H; Karaplis, Andrew C.; Peng, Ji-Bin; Hediger, Matthias A; Goltzman, David; Mohammad, Khalid S.; Guise, Theresa A.; Pollak, Martin R.

    2003-01-01

    The extracellular calcium-sensing receptor (CaR; alternate gene names, CaR or Casr) is a membrane-spanning G protein–coupled receptor. CaR is highly expressed in the parathyroid gland, and is activated by extracellular calcium (Ca2+o). Mice homozygous for null mutations in the CaR gene (CaR–/–) die shortly after birth because of the effects of severe hyperparathyroidism and hypercalcemia. A wide variety of functions have been attributed to CaR. However, the lethal CaR-deficient phenotype has ...

  19. Reactions of fly ash with calcium aluminate cement and calcium sulphate

    OpenAIRE

    Fernández Carrasco, Lucía; Vázquez Ramonich, Enric

    2009-01-01

    The hydration processes in the ternary system fly ash/calcium aluminate cement/calcium sulphate (FA/CAC/C$) at 20 °C were investigated; six compositions from the ternary system FA/CAC/C$ were selected for this study. The nature of the reaction products in these pastes were analysed by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). At four days reaction time, the main hydration reaction product in these pastes was ettringite and the samples with major initial CAC presented minor ett...

  20. Precipitation of calcium carbonate from a calcium acetate and ammonium carbamate batch system

    Science.gov (United States)

    Prah, J.; Maček, J.; Dražič, G.

    2011-06-01

    In this paper, we report a novel approach for preparing precipitated calcium carbonate using solutions of ammonium carbamate and calcium acetate as the sources of calcium and carbon dioxide, respectively. Two different concentrations of the starting solutions at three different temperatures (15, 25 and 50 °C) were used for the reaction. The influence of temperature and concentration on the polymorphism and the resulting morphology of calcium carbonate are discussed. The most important parameter for controlling a particular crystal structure and precipitate morphology were the concentrations of the initial solutions. When initial solutions with lower concentrations were used, the crystal form of the precipitate changed with time. Regardless the different polymorphism at different temperatures, after one day only the calcite form was detected in all samples, regardless of at which temperature the samples were prepared. At higher concentrations, pure vaterite or a mixture of vaterite and calcite were present at the beginning of the experiment. After one day, pure vaterite was found in the samples that were prepared at 15 and 25 °C. If calcium carbonate precipitated at 50 °C, the XRD results showed a mixture of calcite and vaterite regardless of the time at which the sample was taken. The morphology of calcium carbonate particles prepared at various conditions changed from calcite cubes to spherical particles of vaterite and aragonite needles. When a low starting concentration was used, the morphology at the initial stage was strongly affected by the temperature at which the experiments were conducted. However, after one day only, cubes were present in all cases at low initial concentrations. In contrast, at high concentrations spherical particles precipitated at all three temperatures at the beginning of the reaction. Spherical particles were made up from smaller particles. Over time, the size of the particles was diminishing due to their disintegration into