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Sample records for calcium 45

  1. Phagocytosis-induced 45calcium efflux in polymorphonuclear leucocytes

    International Nuclear Information System (INIS)

    The role of calcium ions in regulating the structure and function of non-muscle cells is a subject of intense study. Several lines of evidence that calcium may be essential in the function of polymorphonuclear leucocytes (PMNL) and an important control element in the process of phagocytosis. Direct studies of calcium distribution and fluxes have only recently been undertaken. To our knowledge, no report of calcium movements during normal phagocytosis has been published. In the context of an overall study of calcium dynamics in the PMNL, we report here initial studies on 45Ca efflux in prelabelled guinea pig PMNL. The results demonstrate the energy-dependence of resting calcium efflux and an increased efflux upon addition of phagocytic particles which is not dependent on particle internalization

  2. Localised uptake and extraction of calcium45 in dinoflagellate nuclei

    International Nuclear Information System (INIS)

    The uptake of Ca45 into cells of the dinoflagellate Glenodinium foliaceum was investigated using insoluble compound light microscope autoradiography. The distribution of silver grains showed marked localisation to the dinocaryotic nucleus, with a random scatter of grains over the surrounding protoplasm (cytoplasm and supernumerary nucleus). Correction of grain counts for lateral sensitisation from the dinocaryotic nucleus indicated an isotope concentration 16 32 times greater in this organelle compared to the rest of the cell. Cells labelled for varying periods of time showed differences in the pattern of Ca45 uptake throughout the sample populations, but no increase in the mean level of uptake per cell. This would suggest a rapid incorporation of isotope within 1-2 hours, with little subsequent uptake. The presence of high levels of label after processing with both additive (glutaraldehyde, paraformaldehyde) and coagulative (acetic alcohol) fixatives indicated that the retention of Ca45 in these preparations was not simply a fixation artefact. Although the isotope did not appear to be suitable for (high resolution) electron microscope autoradiography, the intranuclear site of incorporation was demonstrated indirectly using a buffer extraction technique. Prolonged treatment with phosphate buffer resulted in a large scale loss of label from both cytoplasm and dinocaryotic nucleus. The latter appeared to show specific correlation with the loss of (protein) matrix from the chromosomes - as observed under both light and electron microscopy, with no apparent change in either nucleolus or nucleoplasm. This would suggest that incorporated Ca45 in the nucleus was largely confined to the condensed chromatin, where it was combined with the acidic proteins which make up the bulk of the chromatin matrix. The results obtained in this investigation are related to previous studies involving X-ray microanalysis and uptake of Ni63. (Author)

  3. Self-diffusion of calcium-45 into certain carbonates and calcareous soils

    International Nuclear Information System (INIS)

    The investigations described in this paper were prompted by the lack of a reliable and accurate method for measuring exchangeable calcium in calcareous soils. A large group of arid-zone soils contains calcium carbonate and is under irrigation or planned to be irrigated in the future. For the purpose of predicting and measuring the influence of various types of irrigation water on these soils, especially the degree of alkalinization to be expected, an exact determination of exchangeable calcium is necessary. In the various stripping procedures used for the determination of exchangeable cations, the amount of calcium found depends on the solubility of calcium carbonate in the stripping solution and thus on the solution-soil ratio employed. Therefore, the use of an isotopic dilution method of 45Ca seemed most advantageous, also in view of the favourable characteristics of this isotope and its relatively low price. An accurate and easy counting technique employing an ordinary end-window G-M counter and dried-down samples had been developed, overcoming the disadvantage of the low-energy level of the beta-radiation of the isotope and placing its use within the reach even of small laboratories

  4. Calcium Promotes the Formation of Syntaxin 1 Mesoscale Domains through Phosphatidylinositol 4,5-Bisphosphate.

    Science.gov (United States)

    Milovanovic, Dragomir; Platen, Mitja; Junius, Meike; Diederichsen, Ulf; Schaap, Iwan A T; Honigmann, Alf; Jahn, Reinhard; van den Bogaart, Geert

    2016-04-01

    Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a minor component of total plasma membrane lipids, but it has a substantial role in the regulation of many cellular functions, including exo- and endocytosis. Recently, it was shown that PI(4,5)P2and syntaxin 1, a SNARE protein that catalyzes regulated exocytosis, form domains in the plasma membrane that constitute recognition sites for vesicle docking. Also, calcium was shown to promote syntaxin 1 clustering in the plasma membrane, but the molecular mechanism was unknown. Here, using a combination of superresolution stimulated emission depletion microscopy, FRET, and atomic force microscopy, we show that Ca(2+)acts as a charge bridge that specifically and reversibly connects multiple syntaxin 1/PI(4,5)P2complexes into larger mesoscale domains. This transient reorganization of the plasma membrane by physiological Ca(2+)concentrations is likely to be important for Ca(2+)-regulated secretion. PMID:26884341

  5. Enhanced Stability of Calcium Sulfate Scaffolds with 45S5 Bioglass for Bone Repair

    Directory of Open Access Journals (Sweden)

    Cijun Shuai

    2015-11-01

    Full Text Available Calcium sulfate (CaSO4, as a promising tissue repair material, has been applied widely due to its outstanding bioabsorbability and osteoconduction. However, fast disintegration, insufficient mechanical strength and poor bioactivity have limited its further application. In the study, CaSO4 scaffolds fabricated by using selective laser sintering were improved by adding 45S5 bioglass. The 45S5 bioglass enhanced stability significantly due to the bond effect of glassy phase between the CaSO4 grains. After immersing for four days in simulated body fluid (SBF, the specimens with 45S5 bioglass could still retain its original shape compared as opposed to specimens without 45S5 bioglass who experienced disintegration. Meanwhile, its compressive strength and fracture toughness increased by 80% and 37%, respectively. Furthermore, the apatite layer was formed on the CaSO4 scaffolds with 45S5 bioglass in SBF, indicating good bioactivity of the scaffolds. In addition, the scaffolds showed good ability to support the osteoblast-like cell adhesion and proliferation.

  6. Calcium antagonistic effects of Chinese crude drugs: Preliminary investigation and evaluation by 45Ca

    International Nuclear Information System (INIS)

    Coronary and other diseases in cardiac or brain blood vessels are considered to be due to the excessive influx of Ca2+ into cytoplasm. If Ca2+ channels in cell membrane are blocked by medicines or other substances with considerable calcium antagonistic effects, these diseases might be cured or controlled. The influence of some Chinese crude drugs, including Crocus sativus, Carthamus tinctorius, Ginkgo biloba and Bulbus allii macrostemi on Ca2+ influx in isolated rat aortas was investigated by using 45Ca as a radioactive tracer, and their calcium antagonistic effects were evaluated. It can be noted that Ca2+ uptake in isolated rat aorta rings in normal physiological status was not markedly altered by these drugs, whereas the Ca2+ influxes induced by norepinephrine of 1.2 μmol/L and KCl of 100 mmol/L were significantly inhibited by Crocus, Carthamus and Bulbus in a concentration-dependent manner, but not by Ginkgo. The results show that extracellular Ca2+ influx through receptor-operated Ca2+channels and potential-dependent Ca2+channels can be blocked by Crocus, Carthamus and Bulbus. This implies that these Chinese crude drugs have obvious calcium antagonistic effects

  7. The effect of theophylline on the labelling of nitracellular myocardial calcium with 45Ca

    International Nuclear Information System (INIS)

    The effect of theophylline of varying concentration on the labelling of intracellular myocardial calcium was investigated by isotope tests with radioactively labelled Ca (45Ca) in isolated, electrically stimulated left auricles of guinea pigs. The preparates were incubated in a 45Ca solution for 60 minutes, and activity uptake and intracellular Ca concentration were determined. In contrast to earlier investigations, the extracellular Ca was removed after charge by rinsing the resting auricles with inactive, Ca++- and Na+-free choline chloride solution. Under controlled conditions, the intercellular Ca was found to be 45Ca-labelled by about 36% theophylline in 'therapeutical' concentration (5 x 10-4 g/ml) induced a significant increase of the labelled Ca fraction of 16.9% as compared to the controls. 'Toxic' theophylline concentrations, too, lead to a significantly higher absorption of 45Ca. The interchangeable intracellular Ca fraction increased by 11.7% and 10.3% as compared to the untreated preparates. The findings are discussed with regard to earlier investigations on the influence of methylxanthines on the Ca metabolism of the heart. The author assumes that the positively inotropic effect of theophylline and the theophylline-induced contracture may be ascribed to a shift in the intracellular Ca distribution towards ionized Ca. This shift could be explained by a suppression of Ca rebinding in intracellular Ca storage places or by Ca release from these structures. (orig./AK)

  8. Ethanol production at 45 C using preparations of Kluyveromyces marxianus IMB3 immobilized in calcium alginate and kissiris

    Energy Technology Data Exchange (ETDEWEB)

    Love, G. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom); Nigam, P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom); Barron, N. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom); Singh, D. [Microbiology Dept., Haryana Agricultural University, Hisar (India); Marchant, R. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom); McHale, A.P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom)

    1996-10-01

    The thermotolerant yeast, K. marxianus IMB3, was grown in free and immobilized states in batch-fed culture at 45 C and ethanol production was examined over a 61-day period. The organism was grown in the free state, in the free state with mineral kissiris, immobilized in calcium alginate and immobilized in calcium alginate together with kissiris. Initially, reactors were fed every two days with 10% (w/v) glucose-containing media and no significant difference in ethanol production was observed. In subsequent refeeding experiments, reactors were re-fed every two days with 15% (w/v) sucrose-containing media. Although overall ethanol concentrations decreased, production in the immobilized systems was higher. In the final stages fermentations were re-fed every 3 days and although overall ethanol production decreased further, production remained highest in the systems containing calcium alginate and kissiris. (orig.). With 1 tab.

  9. Translocation and bonding of calcium (45Ca) in two-year-old seedlings of spruce (Picea abies[L.] Karst.) and pine (Pinus sylvestris L.)

    International Nuclear Information System (INIS)

    Within the framework of the project ''Effect of liming and magnesium fertilization on the uptake, transport, and chemical bonding form of calcium and magnesium in conifers'', experiments regarding the calcium budget of two-year-old spruce and pine seedlings under conditions of controlled nutrition in a gravel culture were carried out. Two variants of calcium nutrition demonstrated which of the mechanisms in the calcium metabolism of trees are dependent on changes in element availability. Root labelling using the radioactive tracer 45Ca permitted aimed investigation of the uptake and translocation of calcium during shoot formation in May. The functional importance of the investigated nutritive element was characterized by breaking up the total calcium contents (45Ca) into the three essential chemical bonding forms (water-soluble Ca, Ca-pectate, Ca-oxalate) for the different tree fractions.- The culture experiments led to the conclusion that the root tips are most important as sites of calcium uptake. Translocation within the roots to the shoot took place via diffusion and exchange displacement as a function of calcium supply in the nutritive solution. There is no clue to support the assumption of a regulation of calcium uptake in spruces; in pines, by contrast, it cannot be excluded.- From a nutrition-physiological viewpoint, a total calcium content of 2 mg per gramme of dry mass is to be considered as sufficient. As this target is always attained, even where calcium supply is scarce, it is not appropriate to equate increased calcium availability with enhanced nutrient supply. Rather, the results discussed seem to support the theory that the trees now need to detoxicate excessively high calcium concentrations, which are liable to endanger the physiological cell metabolism, by a reaction with oxalic acid resulting in the formation of calcium oxalate. (orig.)

  10. Calcium antagonistic effects of Bambusa Rigida investigated by 45Ca and its protection on myocardial ischemia of rats

    Institute of Scientific and Technical Information of China (English)

    LIN Rushan; YE Ling; YANG Yuanyou; LIAO Jiali; MO Shangwu; LIU Ning

    2008-01-01

    An investigation was conducted using 45Ca as a radioactive tracer to evaluate calcium antagonistic effects of several extracts from Bambusa Rigida in living rats. The relationship between the flavonoid and saccharide contents of Bambusa Rigida and calcium antagonistic effects were also analyzed. The protective effects of the alkali extracts ofBambusa Rigida on myocardial ischemia were investigated in living rats. The results indicated that the alkali extracts of Bambusa Rigida had a prominent influence on Ca2+ influx and efflux in the isolated rat aorta and heart, as they could obviously block 45Ca entering into cells and stimulate efflux of intracellular Ca2+. Moreover, the alkali extracts of Bambusa Rigida had favorable protective effects on myocardial ischemia induced either by isoproterenol injection (ISO) or by the ligation of coronary artery. These results implied that the Bambusa Rigida had attractive potential for the treatment of heart, cerebrovascular and other diseases. However, the conclusion that whether the flavonoid or saccharide in Bambusa Rigida affected the calcium antagonistic effects and Ca2+ channels or not was hard to make within the results of the investigation.

  11. Continuous ethanol fermentation at 45 C using Kluyveromyces marxianus IMB3 immobilized in Calcium alginate and kissiris

    Energy Technology Data Exchange (ETDEWEB)

    Love, G.; Gough, S.; Brady, D.; Barron, N.; Nigam, P.; Marchant, R.; McHale, A.P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom); Singh, D. [Microbiology Dept., Haryana Agricultural University, Hisar (India)

    1998-03-01

    The thermotolerant ethanol-producing yeast strain Kluyveromyces marxianus IMB3 was immobilized in calcium alginate and a 1:1 mixture of calcium alginate and the porous volcanic mineral, kissiris. Immobilized preparations were placed in fixed-bed column bioreactors and continuous ethanol production by systems containing both immobilized preparations was examined at 45 C with a 100 g/l glucose feed. The effect of residence time on product concentration, bioreactor efficiency and volumetric productivities have been examined and these were all higher in systems containing the alginate/kissiris mixed immobilization matrix. Maximum ethanol concentrations produced by the continuous system ranged between 46 and 48 g/l representing efficiencies of 90-94%. (orig.) With 1 tab., 13 refs.

  12. The influence of ionizing radiation at the alkaline phosphatase activity and calcium 45 transport under hypothyroid conditions

    International Nuclear Information System (INIS)

    The experiments with 2-month-old hypothyroid male rats (mercasolil 10 mg/kg per os during 21 days) have shown that total gamma-irradiation ( 0,5 Gy) caused phased changes of alkaline phosphatase - its reduction in the first dates of the investigation (3, 10 and 30 days), normal activity in a 90 days and repeated drop of the activity at the end of the experiment (180 days). In a 3 and 10 days after irradiation it was revealed the diminish of the calcium-accumulated ability of the duodenum mucous membrane in the hypothyroid rats. So it was concluded that combined action of radiation and mercasolil leaded to a decrease in calcium 45 transport in the duodenum and reduction in the activity of thermo labile isoenzyme of alkaline phosphatase in blood serum

  13. Different effects of R 56865 and calcium entry blockers on K+- and noradrenaline-induced contractions and45Ca uptake in rat aorta

    NARCIS (Netherlands)

    Koch, P.; Wilhelm, D.; Wermelskirchen, D.; Nebel, U.; Wilffert, B.; Peters, Thies

    1988-01-01

    The effects of R 56865, nifedipine, verapamil, diltiazem and flunarizine on K+- and NA-induced contractions and K+-induced45Ca uptake were compared in the isolated rat aorta. The calcium entry blockers concentration dependently inhibited the K+-induced contraction and45Ca uptake over the same dose-r

  14. Effect of 50 Hz sinusoidal electromagnetic field on 45Calcium uptake and bone resorption

    International Nuclear Information System (INIS)

    The hypothesis that exposure to weak exogenous electromagnetic field emulates physiological and strain related electrical currents which stimulate the bone formation, has been evaluated in this study. It was observed that a dose dependent increase in 45Ca levels in tibias of animals exposed to sinusoidal EMF full day for 30 days as compared to control animals

  15. Calcium transport in sealed vesicles from red beet (Beta vulgaris L.) storage tissue. II. Characterization of 45Ca2+ uptake into plasma membrane vesicles

    International Nuclear Information System (INIS)

    Calcium uptake was examined in sealed plasma membrane vesicles isolated from red beet (Beta vulgaris L.) storage tissue using 45Ca2+. Uptake of 45Ca2+ by the vesicles was ATP-dependent and radiotracer accumulated by the vesicles could be released by the addition of the calcium ionophore A23187. The uptake was stimulated by gramicidin D but slightly inhibited by carbonylcyanide m-chlorophenylhydrazone. Although the latter result might suggest some degree of indirect coupling of 45Ca2+ uptake to ATP utilization via ΔμH+, no evidence for a secondary H+/Ca2+ antiport in this vesicle system could be found. Following the imposition of an acid-interior pH gradient, proton efflux from the vesicle was not enhanced by the addition of Ca2+ and an imposed pH gradient could not drive 45Ca2+ uptake. Optimal uptake of 45Ca2+ occurred broadly between pH 7.0 and 7.5 and the transport was inhibited by orthovanadate, N,N'-dicyclohexylcarbodiimide, and diethylstilbestrol but insensitive to nitrate and azide. The dependence of 45Ca2+ uptake on both calcium and Mg:ATP concentration demonstrated saturation kinetics with K/sub m/ values of 6 micromolar and 0.37 millimolar, respectively. While ATP was the preferred substrate for driving 45Ca2+ uptake, GTP could drive transport at about 50% of the level observed for ATP. The results of this study demonstrate the presence of a unique primary calcium transport system associated with the plasma membrane which could drive calcium efflux from the plant cell

  16. Calcium transport in sealed vesicles from red beet (Beta vulgaris L. ) storage tissue. II. Characterization of /sup 45/Ca/sup 2 +/ uptake into plasma membrane vesicles

    Energy Technology Data Exchange (ETDEWEB)

    Giannini, J.L.; Ruiz-Cristin, J.; Briskin, D.P.

    1987-12-01

    Calcium uptake was examined in sealed plasma membrane vesicles isolated from red beet (Beta vulgaris L.) storage tissue using /sup 45/Ca/sup 2 +/. Uptake of /sup 45/Ca/sup 2 +/ by the vesicles was ATP-dependent and radiotracer accumulated by the vesicles could be released by the addition of the calcium ionophore A23187. The uptake was stimulated by gramicidin D but slightly inhibited by carbonylcyanide m-chlorophenylhydrazone. Although the latter result might suggest some degree of indirect coupling of /sup 45/Ca/sup 2 +/ uptake to ATP utilization via ..delta mu..H/sup +/, no evidence for a secondary H/sup +//Ca/sup 2 +/ antiport in this vesicle system could be found. Following the imposition of an acid-interior pH gradient, proton efflux from the vesicle was not enhanced by the addition of Ca/sup 2 +/ and an imposed pH gradient could not drive /sup 45/Ca/sup 2 +/ uptake. Optimal uptake of /sup 45/Ca/sup 2 +/ occurred broadly between pH 7.0 and 7.5 and the transport was inhibited by orthovanadate, N,N'-dicyclohexylcarbodiimide, and diethylstilbestrol but insensitive to nitrate and azide. The dependence of /sup 45/Ca/sup 2 +/ uptake on both calcium and Mg:ATP concentration demonstrated saturation kinetics with K/sub m/ values of 6 micromolar and 0.37 millimolar, respectively. While ATP was the preferred substrate for driving /sup 45/Ca/sup 2 +/ uptake, GTP could drive transport at about 50% of the level observed for ATP. The results of this study demonstrate the presence of a unique primary calcium transport system associated with the plasma membrane which could drive calcium efflux from the plant cell.

  17. Calcium dynamics in the healing of tooth extraction sockets in mice evaluated using 45Ca-autoradiography and Electron Probe Micro Analysis

    International Nuclear Information System (INIS)

    The calcium distribution in tooth extraction sockets of mice was examined using 45-Calcium autoradiography (ARG) and Electron Probe Micro Analysis (EPMA). Mice were divided into 8 groups (n=8) according to the number of days (1, 2, 3, 4, 5, 7, 10, 20 respectively) after extraction. Frozen sections were taken from mice on each experimental day after injection of 45-Calcium (RI). The process of formation of new bone was observed using ARG. An ultimate analysis was performed by EPMA. Histological analysis was performed with toluidine blue- and alizarin red S-staining. In toluidine blue-staining, an osteoblast was found along the socket wall at 4 days and non-calcified periodontal ligament was recognized until 5 days after extraction. In alizarin red S-staining, new bone was recognized separated from the socket wall at 4 days after extraction. 45Ca-labeling was detected strongly in the periosteum of the mandible, the surface of cement and periodontal ligament in control animals. 45Ca-labeling was moved from the bottom to the top of the tooth extraction socket during the period from 1 to 5 days after extraction, but in the periodontal ligament lower than in the granulation tissue. 45Ca-labeling was detected in the socket at 7, 10 and 20 days. At 4 days, calcium phosphate was observed in the central portion of the socket using EPMA. 45Ca-labeling showed deposition of calcium phosphate for alveolar bone and new bone. These results suggest that the granulation tissue may be involved in the initial calcification in the tooth extraction socket and lead to the formation of new bone in it. (author)

  18. Serum ionised calcium and cardiovascular disease in 45-years old men and women followed for 18 years

    DEFF Research Database (Denmark)

    Ogard, Christina Gerlach; Petersen, Janne; Jørgensen, Torben;

    2006-01-01

    High level of total serum calcium within the normal range has been associated with increased cardiovascular risk. We wanted to evaluate whether the physiological active ionised form of calcium also was a risk factor for cardiovascular disease (CVD). Methods: A total of 974 participants from...... a health survey in 1981 in Copenhagen had ionised serum calcium and different cardiovascular risk factors measured. The participants were followed until 1999 in The National Hospital Patients Registry and The National Death Registry in Denmark regarding the diagnosis ischemic heart disease (IHD......) and a broader definition of CVD. Persons with ionised serum calcium in the highest quintile were compared with persons in the lower four quintiles. Results: In a univariate analysis persons with ionised serum calcium in the highest quintile had increased risk of IHD (p=0.001) and CVD (p=0.02) compared...

  19. XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite-Bioglass (registered) 45S5 co-sintered bioceramics

    International Nuclear Information System (INIS)

    Bioglass (registered) 45S5 was co-sintered with hydroxyapatite at 1200 deg. C. When small amounts (5(PO4)2SiO4 and Na3Ca6(PO4)5 in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite-Bioglass (registered) 45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L2,3-edge and calcium (Ca) K-edge XANES. Si L2,3-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination. Using P L2,3-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and β-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na3Ca6(PO4)5 in a silicate matrix indicating that it is more soluble compared to the other compositions.

  20. A COMPARATIVE ANALYSIS ON CALCIUM RELEASE FROM ENAMEL AFTER TREATMENT WITH VARIOUS REMINERALIZING AGENTS AT A PH 4.5 : AN ATOMIC ABSORBTION SPECTROMETRIC ANALYSIS

    Directory of Open Access Journals (Sweden)

    Shetty Shishir

    2013-07-01

    Full Text Available Focus of this study was to compare the amount of calcium released from enamel treated with different remineralizing agents at pH 4.5 using atomic spectrophotometric analysis. The present study was designed to assess the calcium release from enamel when subjected to an acid challenge. Enamel samples were divided into four groups of which intact enamel served the purpose of control group and other three groups were based on the remineralizing agents used (CPP-ACP [GC Tooth Mousse], CPP-ACPF [GC Tooth Mousse Plus], 0.044 % Sodium Fluoride [Phosflur]. All the groups of enamel samples were initially demineralized and followed up with remineralisation by adopting the pH cycling model. Acetate buffer was prepared at a specific pH of 4.5. The enamel samples were subjected to acid challenge in presence of a magnetic stirrer and buffer solution were pipetted at specific time intervals for pH 4.5. The solutions collected were transferred into sterile containers and subjected to atomic spectrometry analysis.

  1. Synthetic peptides corresponding to human follicle-stimulating hormone (hFSH)-beta-(1-15) and hFSH-beta-(51-65) induce uptake of 45Ca++ by liposomes: evidence for calcium-conducting transmembrane channel formation

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, P.; Santa-Coloma, T.A.; Reichert, L.E. Jr. (Department of Biochemistry, Albany Medical College, New York, NY (USA))

    1991-06-01

    We have previously described FSH receptor-mediated influx of 45Ca++ in cultured Sertoli cells from immature rats and receptor-enriched proteoliposomes via activation of voltage-sensitive and voltage-independent calcium channels. We have further shown that this effect of FSH does not require cholera toxin- or pertussis toxin-sensitive guanine nucleotide binding protein or activation of adenylate cyclase. In the present study, we have identified regions of human FSH-beta-subunit which appear to be involved in mediating calcium influx. We screened 11 overlapping peptide amides representing the entire primary structure of hFSH-beta-subunit for their effects on 45Ca++ flux in FSH receptor-enriched proteoliposomes. hFSH-beta-(1-15) and hFSH-beta-(51-65) induced uptake of 45Ca++ in a concentration-related manner. This effect of hFSH-beta-(1-15) and hFSH-beta-(51-65) was also observed in liposomes lacking incorporated FSH receptor. Reducing membrane fluidity by incubating liposomes (containing no receptor) with hFSH-beta-(1-15) or hFSH-beta-(51-65) at temperatures lower than the transition temperatures of their constituent phospholipids resulted in no significant (P greater than 0.05) difference in 45Ca++ uptake. The effectiveness of the calcium ionophore A23187, however, was abolished. Ruthenium red, a voltage-independent calcium channel antagonist, was able to completely block uptake of 45Ca++ induced by hFSH-beta-(1-15) and hFSH-beta-(51-65) whereas nifedipine, a calcium channel blocker specific for L-type voltage-sensitive calcium channels, was without effect. These results suggest that in addition to its effect on voltage-sensitive calcium channel activity, interaction of FSH with its receptor may induce formation of transmembrane aqueous channels which also facilitate influx of extracellular calcium.

  2. Synthetic peptides corresponding to human follicle-stimulating hormone (hFSH)-beta-(1-15) and hFSH-beta-(51-65) induce uptake of 45Ca++ by liposomes: evidence for calcium-conducting transmembrane channel formation

    International Nuclear Information System (INIS)

    We have previously described FSH receptor-mediated influx of 45Ca++ in cultured Sertoli cells from immature rats and receptor-enriched proteoliposomes via activation of voltage-sensitive and voltage-independent calcium channels. We have further shown that this effect of FSH does not require cholera toxin- or pertussis toxin-sensitive guanine nucleotide binding protein or activation of adenylate cyclase. In the present study, we have identified regions of human FSH-beta-subunit which appear to be involved in mediating calcium influx. We screened 11 overlapping peptide amides representing the entire primary structure of hFSH-beta-subunit for their effects on 45Ca++ flux in FSH receptor-enriched proteoliposomes. hFSH-beta-(1-15) and hFSH-beta-(51-65) induced uptake of 45Ca++ in a concentration-related manner. This effect of hFSH-beta-(1-15) and hFSH-beta-(51-65) was also observed in liposomes lacking incorporated FSH receptor. Reducing membrane fluidity by incubating liposomes (containing no receptor) with hFSH-beta-(1-15) or hFSH-beta-(51-65) at temperatures lower than the transition temperatures of their constituent phospholipids resulted in no significant (P greater than 0.05) difference in 45Ca++ uptake. The effectiveness of the calcium ionophore A23187, however, was abolished. Ruthenium red, a voltage-independent calcium channel antagonist, was able to completely block uptake of 45Ca++ induced by hFSH-beta-(1-15) and hFSH-beta-(51-65) whereas nifedipine, a calcium channel blocker specific for L-type voltage-sensitive calcium channels, was without effect. These results suggest that in addition to its effect on voltage-sensitive calcium channel activity, interaction of FSH with its receptor may induce formation of transmembrane aqueous channels which also facilitate influx of extracellular calcium

  3. XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite-Bioglass (registered) 45S5 co-sintered bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, Hande [Graduate Student, Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States); Hu Yongfeng; Zuin, Lucia [Beamline Scientist, Canadian Light Source, Saskatoon, SK (Canada); Appathurai, Narayana [Beamline Scientist, Synchrotron Radiation Center, Madison, WI (United States); Aswath, Pranesh B., E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States)

    2011-03-12

    Bioglass (registered) 45S5 was co-sintered with hydroxyapatite at 1200 deg. C. When small amounts (< 5 wt.%) of Bioglass (registered) 45S5 was added it behaved as a sintering aid and also enhanced the decomposition of hydroxyapatite to {beta}-tricalcium phosphate. However when 10 wt.% and 25 wt.% Bioglass (registered) 45S5 was used it resulted in the formation of Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4} and Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite-Bioglass (registered) 45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L{sub 2,3}-edge and calcium (Ca) K-edge XANES. Si L{sub 2,3}-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination. Using P L{sub 2,3}-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and {beta}-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in a silicate matrix indicating that it is more soluble compared to the other compositions.

  4. USP2-45 Is a Circadian Clock Output Effector Regulating Calcium Absorption at the Post-Translational Level.

    Directory of Open Access Journals (Sweden)

    Daniel Pouly

    Full Text Available The mammalian circadian clock influences most aspects of physiology and behavior through the transcriptional control of a wide variety of genes, mostly in a tissue-specific manner. About 20 clock-controlled genes (CCGs oscillate in virtually all mammalian tissues and are generally considered as core clock components. One of them is Ubiquitin-Specific Protease 2 (Usp2, whose status remains controversial, as it may be a cogwheel regulating the stability or activity of core cogwheels or an output effector. We report here that Usp2 is a clock output effector related to bodily Ca2+ homeostasis, a feature that is conserved across evolution. Drosophila with a whole-body knockdown of the orthologue of Usp2, CG14619 (dUsp2-kd, predominantly die during pupation but are rescued by dietary Ca2+ supplementation. Usp2-KO mice show hyperabsorption of dietary Ca2+ in small intestine, likely due to strong overexpression of the membrane scaffold protein NHERF4, a regulator of the Ca2+ channel TRPV6 mediating dietary Ca2+ uptake. In this tissue, USP2-45 is found in membrane fractions and negatively regulates NHERF4 protein abundance in a rhythmic manner at the protein level. In clock mutant animals (Cry1/Cry2-dKO, rhythmic USP2-45 expression is lost, as well as the one of NHERF4, confirming the inverse relationship between USP2-45 and NHERF4 protein levels. Finally, USP2-45 interacts in vitro with NHERF4 and endogenous Clathrin Heavy Chain. Taken together these data prompt us to define USP2-45 as the first clock output effector acting at the post-translational level at cell membranes and possibly regulating membrane permeability of Ca2+.

  5. Fabrication and characterization of nano-HA-45S5 bioglass composite coatings on calcium-phosphate containing micro-arc oxidized CP-Ti substrates

    Energy Technology Data Exchange (ETDEWEB)

    Farnoush, Hamidreza, E-mail: farnoush@aut.ac.ir [Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Kashan, P.O. Box 87317-51167, Kashan (Iran, Islamic Republic of); Muhaffel, Faiz; Cimenoglu, Huseyin [Department of Metallurgical and Materials Engineering, Istanbul Technical University, 34469 Maslak, Istanbul (Turkey)

    2015-01-01

    Highlights: • Introducing a calcium-containing titanium oxide interlayer by MAO on CP-Ti. • EPD was utilized for HA and HA-BG coatings on MAO CP-Ti substrates. • Highest bonding strength was obtained for HA-BG/MAO 360 Ti sample. • Enhancement of corrosion resistance for HA-BG/MAO 360 Ti sample in SBF. - Abstract: In the present study, micro-arc oxidation (MAO) was carried out on commercially pure titanium (CP-Ti) to fabricate porous titanium oxide coatings containing calcium phosphates (CaP) at different applied voltages of 300, 330 and 360 V for 5 min. Subsequently, nano-hydroxyapatite (HA) and HA-45S5 bioglass (BG) composite were effectively coated on micro-arc oxidized substrate by electrophoretic deposition (EPD) at a constant voltage of 30 V for 120 s. The phase, structural agents, microstructure and composition of MAO interlayer and subsequent EPD coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. Thermal stability of the as-deposited coatings was analyzed by simultaneous differential scanning calorimetry and thermal gravimetery. The pull-off adhesion tests showed the highest bonding strength was obtained for HA-BG coating on micro-oxidized sample at 360 V. The results of potentiodynamic polarization and impedance spectroscopic measurements in simulated body fluid solution depicted that the combination of MAO treatment at 360 V and EPD of HA-BG composite could effectively increase the corrosion resistance of CP-Ti substrates.

  6. Fabrication and characterization of nano-HA-45S5 bioglass composite coatings on calcium-phosphate containing micro-arc oxidized CP-Ti substrates

    International Nuclear Information System (INIS)

    Highlights: • Introducing a calcium-containing titanium oxide interlayer by MAO on CP-Ti. • EPD was utilized for HA and HA-BG coatings on MAO CP-Ti substrates. • Highest bonding strength was obtained for HA-BG/MAO 360 Ti sample. • Enhancement of corrosion resistance for HA-BG/MAO 360 Ti sample in SBF. - Abstract: In the present study, micro-arc oxidation (MAO) was carried out on commercially pure titanium (CP-Ti) to fabricate porous titanium oxide coatings containing calcium phosphates (CaP) at different applied voltages of 300, 330 and 360 V for 5 min. Subsequently, nano-hydroxyapatite (HA) and HA-45S5 bioglass (BG) composite were effectively coated on micro-arc oxidized substrate by electrophoretic deposition (EPD) at a constant voltage of 30 V for 120 s. The phase, structural agents, microstructure and composition of MAO interlayer and subsequent EPD coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. Thermal stability of the as-deposited coatings was analyzed by simultaneous differential scanning calorimetry and thermal gravimetery. The pull-off adhesion tests showed the highest bonding strength was obtained for HA-BG coating on micro-oxidized sample at 360 V. The results of potentiodynamic polarization and impedance spectroscopic measurements in simulated body fluid solution depicted that the combination of MAO treatment at 360 V and EPD of HA-BG composite could effectively increase the corrosion resistance of CP-Ti substrates

  7. Fabrication and characterization of nano-HA-45S5 bioglass composite coatings on calcium-phosphate containing micro-arc oxidized CP-Ti substrates

    Science.gov (United States)

    Farnoush, Hamidreza; Muhaffel, Faiz; Cimenoglu, Huseyin

    2015-01-01

    In the present study, micro-arc oxidation (MAO) was carried out on commercially pure titanium (CP-Ti) to fabricate porous titanium oxide coatings containing calcium phosphates (CaP) at different applied voltages of 300, 330 and 360 V for 5 min. Subsequently, nano-hydroxyapatite (HA) and HA-45S5 bioglass (BG) composite were effectively coated on micro-arc oxidized substrate by electrophoretic deposition (EPD) at a constant voltage of 30 V for 120 s. The phase, structural agents, microstructure and composition of MAO interlayer and subsequent EPD coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. Thermal stability of the as-deposited coatings was analyzed by simultaneous differential scanning calorimetry and thermal gravimetery. The pull-off adhesion tests showed the highest bonding strength was obtained for HA-BG coating on micro-oxidized sample at 360 V. The results of potentiodynamic polarization and impedance spectroscopic measurements in simulated body fluid solution depicted that the combination of MAO treatment at 360 V and EPD of HA-BG composite could effectively increase the corrosion resistance of CP-Ti substrates.

  8. Production of ethanol from molasses at 45 C using Kluyveromyces marxianus IMB3 immobilized in calcium alginate gels and poly(vinyl alcohol) cryogel

    Energy Technology Data Exchange (ETDEWEB)

    Gough, S.; Barron, N.; McHale, A.P. [Biotechnology Research Group, Univ. of Ulster (United Kingdom); Zubov, A.L.; Lozinsky, V.I. [Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-08-01

    The thermotolerant, ethanol-producing yeast strain Kluyveromyces marxianus IMB3 has been immobilized in calcium alginate gel and poly(vinyl alcohol) cryogel (PVAC) beads. The immobilized preparations were used as biocatalyst in fed-batch reactor systems for prolonged periods. The substrate utilized in each case consisted of sugar cane molasses diluted to yield a sugar load of 140 g/l. During the first cycle the maximum ethanol concentration produced by the alginate system was 57 g/l, representing 80% of the maximum theoretical yield. In the system employing the PVAC-immobilized biocatalyst, ethanol production increased to a maximum of 52-53 g/l, representing 73% of the maximum theoretical yield. In both cases, maximum ethanol concentration was achieved within a 72-hour period. When each system was operated on a fed-batch basis for a prolonged period of time the average ethanol concentrations produced in the alginate- and the PVAC-immobilized systems were 21 and 45 g/l, respectively. The results suggest that the PVAC-based immobilization system may provide a more practical alternative to alginate for the production of ethanol by K. marxianus IMB3 in continuous or semi-continuous fermentation systems. (orig.) With 1 fig., 13 refs.

  9. Influence of extra-cellular and intra-cellular acting thiol oxidants on the 45calcium uptake by the islets of Langerhans of the rat

    International Nuclear Information System (INIS)

    The glucose-stimulated calcium uptake by the islets of Langerhans is dependent on the intra-cellular GSH/GSSG ratios. The inhibition of calcium uptake is not the consequence of a direct oxidation of membrane-fixed thiol groups. In contrast, direct oxidation of extra cellular thiols leads to an increase in calcium uptake when intra-cellular oxidation is simultaneously prevented. Since this effect only occurs at high intra-cellular GSH/GSSG ratios it can be assumed that the redox state of extra-cellular thiols is dependent on the redox state of the intra-cellular GSH/GSSG ratios. These findings support the theory that the oxidation of extra-cellular thiols by thiol oxidants leads to an increase in calcium uptake and that the extent of uptake is higher, the more the redox state of the extra-cellular thiols tends towards the reduced state prior to oxidation. (orig./MG)

  10. 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 ...

  11. 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 ...

  12. 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...

  13. Contribution of intracellular calcium and pH in ischemic uncoupling of cardiac gap junction channels formed of connexins 43, 40, and 45: a critical function of C-terminal domain.

    Directory of Open Access Journals (Sweden)

    Giriraj Sahu

    Full Text Available Ischemia is known to inhibit gap junction (GJ mediated intercellular communication. However the detail mechanisms of this inhibition are largely unknown. In the present study, we determined the vulnerability of different cardiac GJ channels formed of connexins (Cxs 43, 40, and 45 to simulated ischemia, by creating oxygen glucose deprived (OGD condition. 5 minutes of OGD decreased the junctional conductance (Gj of Cx43, Cx40 and Cx45 by 53±3%, 64±1% and 85±2% respectively. Reduction of Gj was prevented completely by restricting the change of both intracellular calcium ([Ca(2+]i and pH (pHi with potassium phosphate buffer. Clamping of either [Ca(2+]i or pHi, through BAPTA (2 mM or HEPES (80 mM respectively, offered partial resistance to ischemic uncoupling. Anti-calmodulin antibody attenuated the uncoupling of Cx43 and Cx45 significantly but not of Cx40. Furthermore, OGD could reduce only 26±2% of Gj in C-terminus (CT truncated Cx43 (Cx43-Δ257. Tethering CT of Cx43 to the CT-truncated Cx40 (Cx40-Δ249, and Cx45 (Cx45-Δ272 helped to resist OGD mediated uncoupling. Moreover, CT domain played a significant role in determining the junction current density and plaque diameter. Our results suggest; OGD mediated uncoupling of GJ channels is primarily due to elevated [Ca(2+]i and acidic pHi, though the latter contributes more. Among Cx43, Cx40 and Cx45, Cx43 is the most resistant to OGD while Cx45 is the most sensitive one. CT of Cx43 has major necessary elements for OGD induced uncoupling and it can complement CT of Cx40 and Cx45.

  14. Transfer of 45Ca and 36Cl at the blood-nerve barrier of the sciatic nerve in rats fed low or high calcium diets

    International Nuclear Information System (INIS)

    Unidirectional fluxes of 45Ca, 36Cl, and of [3H]mannitol from blood into the sciatic nerve and cerebral cortex were determined from 5- and 15-min uptakes of these tracers after an intravenous (i.v.) bolus injection in awake rats. Rats were fed diets for 8 wk, that had either a low (0.01% wt/wt), normal (0.67%), or high (3%) Ca content. Plasma [Ca] was 32% less and 11% more in rats fed low (LOCA) and high Ca diets (HICA), respectively, than in rats fed a normal Ca diet (CONT). The mean permeability-surface area product (PA) of 45Ca at the blood-nerve barrier was about eightfold higher than at the blood-brain barrier in the same animals and did not differ significantly between groups (greater than 0.05). Mean PA ratios of 45Ca/36Cl for the blood-nerve and blood-brain barriers in CONT rats, 0.52 ± 0.04 and 0.40 ± 0.02, respectively, were not significantly different from corresponding ratios in LOCA and HICA groups, and corresponded to the aqueous limiting diffusion ratio (0.45). The authors results show no evidence for concentration-dependent transport of Ca over a plasma [Ca] range of 0.8-1.4 mmol/liter at the blood-nerve barrier of the rat peripheral nerve, and suggest that Ca and Cl exchange slowly between nerve and blood via paracellular pathways

  15. Effectiveness of acidic calcium sulfate with propionic and lactic acid and lactates as postprocessing dipping solutions to control Listeria monocytogenes on frankfurters with or without potassium lactate and stored vacuum packaged at 4.5 degrees C.

    Science.gov (United States)

    Nuñez de Gonzalez, Maryuri T; Keeton, Jimmy T; Acuff, Gary R; Ringer, Larry J; Lucia, Lisa M

    2004-05-01

    The safety of ready-to-eat meat products such as frankfurters can be enhanced by treating with approved antimicrobial substances to control the growth of Listeria monocytogenes. We evaluated the effectiveness of acidic calcium sulfate with propionic and lactic acid, potassium lactate, or lactic acid postprocessing dipping solutions to control L. monocytogenes inoculated (ca. 10(8) CFU/ml) onto the surface of frankfurters with or without potassium lactate and stored in vacuum packages at 4.5 degrees C for up to 12 weeks. Two frankfurter formulations were manufactured without (control) or with potassium lactate (KL, 3.3% of a 60% [wt/wt] commercially available syrup). After cooking, chilling, and peeling, each batch was divided into inoculated (four strains of L. monocytogenes mixture) and noninoculated groups. Each group was treated with four different dips: (i) control (saline solution), (ii) acidic calcium sulfate with propionic and lactic acid (ACS, 1:2 water), (iii) KL, or (iv) lactic acid (LA, 3.4% of a 88% [wt/wt] commercially available syrup) for 30 s. Noninoculated frankfurters were periodically analyzed for pH, water activity, residual nitrite, and aerobic plate counts (APCs), and L. monocytogenes counts (modified Oxford medium) were determined on inoculated samples. Surface APC counts remained at or near the lower limit of detection (dip, which indicated a residual bactericidal effect when L. monocytogenes populations were monitored over 12 weeks. L. monocytogenes numbers were also reduced, but not to the same degree in franks made without or with KL and treated with LA. These results revealed the effectiveness of ACS (bactericidal effect) or LA (bacteriostatic effect) as postprocessing dipping solutions to inhibit or control the growth of L. monocytogenes on vacuum-packaged frankfurters stored at 4.5 degrees C for up to 12 weeks. PMID:15151227

  16. The application of spectrographic analysis to the radioisotope production control. II. Analysis of calcium-45, scandium-46, nickel-63, and copper-64 solutions

    International Nuclear Information System (INIS)

    Semi-quantitative and quantitative determinations of both the radioactive and the target element in each radioisotope are described. The copper-spark technique was used except for Cu determinations, that need silver or.graphite electro des. Inter-element effects and their compensation through the use of Bi, 6a, In, Ho, Pd, TI and Y as reference elements was examined. For the determination of Ca in Ca-45 samples, Ba, La, Li and Sr were also tested. Good results are achieved with Li for Ca, Y for Sc,Ti and Ni, and either In or Y for Cu and Zn. (Author) 7 refs

  17. 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

  18. Ca2+ Influx through Store-operated Calcium Channels Replenishes the Functional Phosphatidylinositol 4,5-Bisphosphate Pool Used by Cysteinyl Leukotriene Type I Receptors.

    Science.gov (United States)

    Alswied, Abdullah; Parekh, Anant B

    2015-12-01

    Oscillations in cytoplasmic Ca(2+) concentration are a universal mode of signaling following physiological levels of stimulation with agonists that engage the phospholipase C pathway. Sustained cytoplasmic Ca(2+) oscillations require replenishment of the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2), the source of the Ca(2+)-releasing second messenger inositol trisphosphate. Here we show that cytoplasmic Ca(2+) oscillations induced by cysteinyl leukotriene type I receptor activation run down when cells are pretreated with Li(+), an inhibitor of inositol monophosphatases that prevents PIP2 resynthesis. In Li(+)-treated cells, cytoplasmic Ca(2+) signals evoked by an agonist were rescued by addition of exogenous inositol or phosphatidylinositol 4-phosphate (PI4P). Knockdown of the phosphatidylinositol 4-phosphate 5 (PIP5) kinases α and γ resulted in rapid loss of the intracellular Ca(2+) oscillations and also prevented rescue by PI4P. Knockdown of talin1, a protein that helps regulate PIP5 kinases, accelerated rundown of cytoplasmic Ca(2+) oscillations, and these could not be rescued by inositol or PI4P. In Li(+)-treated cells, recovery of the cytoplasmic Ca(2+) oscillations in the presence of inositol or PI4P was suppressed when Ca(2+) influx through store-operated Ca(2+) channels was inhibited. After rundown of the Ca(2+) signals following leukotriene receptor activation, stimulation of P2Y receptors evoked prominent inositol trisphosphate-dependent Ca(2+) release. Therefore, leukotriene and P2Y receptors utilize distinct membrane PIP2 pools. Our findings show that store-operated Ca(2+) entry is needed to sustain cytoplasmic Ca(2+) signaling following leukotriene receptor activation both by refilling the Ca(2+) stores and by helping to replenish the PIP2 pool accessible to leukotriene receptors, ostensibly through control of PIP5 kinase activity. PMID:26468289

  19. Balanço de cálcio e fósforo e estudo dos níveis desses minerais em dietas para codornas japonesas (45 a 57 semanas de idade Balance of calcium and phosphorus and study of these minerals in diets for Japanese quails (from 45 to 57 weeks of age

    Directory of Open Access Journals (Sweden)

    Carlos Henrique Rocha Costa

    2010-08-01

    Full Text Available Objetivou-se verificar o efeito de quatro níveis de cálcio (Ca e de fósforo disponível (Pd na dieta sobre o desempenho, a qualidade dos ovos e a excreção mineral em codornas japonesas durante o terço final do ciclo de produção. Utilizaram-se 384 codornas, com 313 dias de idade, distribuídas em delineamento inteiramente casualizado em esquema fatorial 4 × 2, composto de quatro níveis de cálcio (2,0; 2,5; 3,0 e 3,5% e dois de fósforo disponível (0,15 e 0,35%, de modo que cada combinação foi avaliada em seis repetições de oito aves. As dietas experimentais foram isoproteicas (19,31% de PB, isocalóricas (2.800 kcal de EM/kg e isoaminoacídicas. Foram avaliados a produção, o peso, a massa, a altura e o diâmetro dos ovos, o consumo de ração, a conversão alimentar, a viabilidade, o peso específico, os componentes dos ovos (peso e porcentagem de casca, albúmem e gema, o balanço de cálcio e fósforo total e a excreção de matéria mineral. Não houve interação dos níveis de cálcio e fósforo disponível utilizados. O aumento do nível de cálcio na dieta melhorou linearmente a conversão por dúzia e reduziu o consumo. Promoveu também aumento no peso específico, no peso e na porcentagem de casca e redução linear no peso da gema e aumentou o teor de cálcio nas excretas. A viabilidade e o teor de fósforo nas excretas aumentaram com o acréscimo de fósforo disponível, enquanto as demais variáveis não foram influenciadas pelos níveis de cálcio e fósforo disponível da dieta. Os níveis de 3,5% de cálcio e o de 0,15% de fósforo disponível são suficientes para proporcionar bom desempenho produtivo e manutenção satisfatória da qualidade dos ovos de codornas japonesas no terço final de postura (45 a 57 semanas de idade, e correspondem a consumos diários de 899 mg de cálcio e 40 mg de fósforo disponível por ave.This experiment was conducted aiming to verify the effect of four levels of calcium (Ca and

  20. Comparison of growth-induced resorption and denervation-induced resorption on the release of [3H]tetracycline, 45calcium, and [3H]collagen from whole bones of growing rats

    International Nuclear Information System (INIS)

    The major effect of immobilization during growth is a smaller bone mass induced by either an increased bone resorption or a decreased bone formation. Using a method of analyzing radioisotopic loss of [3H]tetracycline and [3H]collagen from bone prelabeled in vivo, we compared the amount of bone resorption due to immobilization with bone resorption induced by growth. One hind limb was denervated in growing male rats, 6 weeks of age, that had been chronically prelabeled with [3H]tetracycline, 45calcium, and [3H]proline. The total radioactivity of the whole femur and tibia/fibula from the denervated limb was compared with that from bones of the control limb at 0, 1, 2, 4, and 8 weeks after denervation. The effect of growth on bone formation was measured by net increases in bone length, volume, and mass of matrix and mineral. Experimental bones had a significantly smaller volume and mass. Bone resorption was much greater during growth modeling than during denervation. The additional bone resorption induced by denervation was a small fraction (one-fourth) of the resorption induced by growth. Denervation during growth resulted in less bone being formed due to a smaller gain in matrix and mineral mass as a result of a reduction in bone formation

  1. 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 ...

  2. 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...

  3. 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 ...

  4. 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 ...

  5. 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. ...

  6. 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 ...

  7. 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 ...

  8. Calcium electrotransfer for termination of transgene expression in muscle

    DEFF Research Database (Denmark)

    Hojman, Pernille; Spanggaard, Iben; Olsen, Caroline Holkman;

    2011-01-01

    clinical grade calcium solution (20 μl, 168 mM) was injected into transfected mouse or rat tibialis cranialis muscle. Ca(2+) uptake was quantified using calcium 45 ((45)Ca), and voltage and time between injection and pulsation were varied. Extinction of transgene expression was investigated by using both...

  9. 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

  10. 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.

  11. 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 ...

  12. 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 ...

  13. 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 ...

  14. 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 ...

  15. 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 ...

  16. 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 ...

  17. Measurement of slowly exchanging45Ca in rat aorta without using EGTA or lanthanum and its application to quantify the effects of the calcium entry blockers nifedipine and verapamil

    NARCIS (Netherlands)

    Wermelskirchen, D.; Wilhelm, D.; Wilffert, B.; Pegram, B.L.; Hunter, J.; Nebel, U.; Peters, Thies

    1988-01-01

    In rat aortic strips a method was developed to measure a fraction of slowly exchanging45Ca, which correlates with contraction and the cytosolic Ca pool that is enhanced by K+-induced depolarization. In this method no EGTA or lanthanum are used, but the strips are washed for 45 min with a Tyrode solu

  18. 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 ...

  19. 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

  20. 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...

  1. Calcium transport abnormality in uremic rat brain synaptosomes.

    OpenAIRE

    Fraser, C.L.; Sarnacki, P; Arieff, A I

    1985-01-01

    Brain calcium is elevated in patients and laboratory animals with uremia. The significance of this finding is unclear. We evaluated calcium transport in brain of both normal and acutely uremic rats (blood urea nitrogen = 250 mg/dl) by performing studies in synaptosomes from rat brain cerebral cortex. Synaptosomes are vesicular presynaptic nerve endings from brain that contain mitochondria and are metabolically active. Two mechanisms of calcium transport were evaluated using radioactive 45Ca++...

  2. 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

  3. 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 ...

  4. 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 ...

  5. 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 ...

  6. 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 ...

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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...

  14. 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...

  15. 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

  16. Calcium regulation in frog peripheral nerve by the blood-nerve barrier

    International Nuclear Information System (INIS)

    The objectives of this research were: (a) to investigate the characteristics of calcium transport across the perineurium and the endoneurial capillaries, and (b) to gain a better understanding of the extent of calcium homeostasis in the endoneurial space. To study the nature of calcium transport across the perineurium, the flux of radiotracer 45Ca was measured through the perineurial cylinder, isolated from the frog sciatic nerve, and through the perineurium into the nerve in situ. To study the nature of calcium transport across the endoneurial capillaries, the permeability-surface area product (PA) of 45Ca was determined as a function of the calcium concentration in the blood. To study calcium homeostasis, the calcium content of the frog sciatic nerve was determined as a function of chronic changes in plasma [Ca

  17. ATP- and gap junction-dependent intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jorgensen, N R; Geist, S T; Civitelli, R;

    1997-01-01

    stores. In one model, IP3 traverses gap junctions and initiates the release of intracellular calcium stores in neighboring cells. Alternatively, calcium waves may be mediated not by gap junctional communication, but rather by autocrine activity of secreted ATP on P2 purinergic receptors. We studied...... connexin43 (Cx43), are well dye coupled, and lack P2U receptors, transmitted slow gap junction-dependent calcium waves that did not require release of intracellular calcium stores. UMR 106-01 cells predominantly express the gap junction protein connexin 45 (Cx45), are poorly dye coupled, and express P2U...... receptors; they propagated fast calcium waves that required release of intracellular calcium stores and activation of P2U purinergic receptors, but not gap junctional communication. ROS/P2U transfectants and UMR/Cx43 transfectants expressed both types of calcium waves. Gap junction-independent, ATP...

  18. 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...

  19. 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...

  20. Regulation of intracellular calcium in resting and stimulated rat basophilic leukemia cells

    International Nuclear Information System (INIS)

    Intracellular calcium regulation was studied in a cell line of mast cells, the rat basophilic leukemia (RBL) cells with the purpose of determining (1) The properties of the plasma membrane calcium permeability pathway and (2) The role of intracellular calcium stores. The first set of experiments showed that depolarization did not induce calcium entry or secretion in resting cells and did inhibit antigen-stimulated calcium uptake and secretion. In the second set of experiments the ionic basis of antigen-induced depolarization was studied using the fluorescent potential-sensitive probe bis-oxonol. The properties of the calcium entry pathway were more consistent with a calcium channel than a calcium transport mechanism such as Na:Ca exchange. The third set of experiments examined the effects of the proton ionophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) on RBL cells. CCCP inhibited antigen-stimulated 45Ca uptake and secretion by depolarizing the plasma membrane

  1. 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

  2. M45

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    M45 is better known as the Pleiades, a young open cluster in Taurus. Again, this is a very bright (1.6 mag) object known since antiquity. The Pleiades are sometimes referred to as the `Seven Sisters' since that is the number of stars normally visible to the naked eye. In Greek mythology these represent Pleione and her daughters with Atlas: Alcyone, Asterope (a double star), Electra, Maia, Merope,...

  3. Use of technical biochemical in combination for the detection of proteins of union to calcium in Plasmodium falciparum

    International Nuclear Information System (INIS)

    Calcium plays a fundamental role in the development of Plasmodium falciparum, the intracellular parasite that causes malaria. With the purpose of understanding the mechanism by which calcium acts in this parasite, calcium-binding proteins were detected in this organism the combined use of the metachromatic dye Stains-all and the 45Ca overlay assay allowed the identification, in mature parasites. Of 9 calcium - binding proteins. 6 of which seem to be different from any reported calcium-binding protein. Additionally, it was determined that the combined use of these techniques can be useful for the detection and purification of calcium-binding proteins

  4. 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...

  5. 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....

  6. 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)

  7. Role of calcium in growth inhibition induced by a novel cell surface sialoglycopeptide

    Science.gov (United States)

    Betz, N. A.; Westhoff, B. A.; Johnson, T. C.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    Our laboratory has purified an 18 kDa cell surface sialoglycopeptide growth inhibitor (CeReS-18) from intact bovine cerebral cortex cells. Evidence presented here demonstrates that sensitivity to CeReS-18-induced growth inhibition in BALB-c 3T3 cells is influenced by calcium, such that a decrease in the calcium concentration in the growth medium results in an increase in sensitivity to CeReS-18. Calcium did not alter CeReS-18 binding to its cell surface receptor and CeReS-18 does not bind calcium directly. Addition of calcium, but not magnesium, to CeReS-18-inhibited 3T3 cells results in reentry into the cell cycle. A greater than 3-hour exposure to increased calcium is required for escape from CeReS-18-induced growth inhibition. The calcium ionophore ionomycin could partially mimic the effect of increasing extracellular calcium, but thapsigargin was ineffective in inducing escape from growth inhibition. Increasing extracellular calcium 10-fold resulted in an approximately 7-fold increase in total cell-associated 45Ca+2, while free intracellular calcium only increased approximately 30%. However, addition of CeReS-18 did not affect total cell-associated calcium or the increase in total cell-associated calcium observed with an increase in extracellular calcium. Serum addition induced mobilization of intracellular calcium and influx across the plasma membrane in 3T3 cells, and pretreatment of 3T3 cells with CeReS-18 appeared to inhibit these calcium mobilization events. These results suggest that a calcium-sensitive step exists in the recovery from CeReS-18-induced growth inhibition. CeReS-18 may inhibit cell proliferation through a novel mechanism involving altering the intracellular calcium mobilization/regulation necessary for cell cycle progression.

  8. [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

  9. 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

  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. Activation of purified calcium channels by stoichiometric protein phosphorylation

    International Nuclear Information System (INIS)

    Purified dihydropyridine-sensitive calcium channels from rabbit skeletal muscle were reconstituted into phosphatidylcholine vesicles to evaluate the effect of phosphorylation by cyclic AMP-dependent protein kinase (PK-A) on their function. Both the rate and extent of 45Ca2+ uptake into vesicles containing reconstituted calcium channels were increased severalfold after incubation with ATP and PK-A. The degree of stimulation of 45Ca2+ uptake was linearly proportional to the extent of phosphorylation of the alpha 1 and beta subunits of the calcium channel up to a stoichiometry of approximately 1 mol of phosphate incorporated into each subunit. The calcium channels activated by phosphorylation were determined to be incorporated into the reconstituted vesicles in the inside-out orientation and were completely inhibited by low concentrations of dihydropyridines, phenylalkylamines, Cd2+, Ni2+, and Mg2+. The results demonstrate a direct relationship between PK-A-catalyzed phosphorylation of the alpha 1 and beta subunits of the purified calcium channel and activation of the ion conductance activity of the dihydropyridine-sensitive calcium channels

  12. 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)

  13. 45 CFR 84.45 - Housing.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Housing. 84.45 Section 84.45 Public Welfare... PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Postsecondary Education § 84.45 Housing. (a) Housing provided by the recipient. A recipient that provides housing to its nonhandicapped students...

  14. 45 CFR 1170.45 - Housing.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Housing. 1170.45 Section 1170.45 Public Welfare... ACTIVITIES Postsecondary Education § 1170.45 Housing. (a) Housing provided by the recipient. A recipient that provides housing to its nonhandicapped students shall provide comparable, convenient, and...

  15. 45 CFR 605.45 - Housing.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Housing. 605.45 Section 605.45 Public Welfare... § 605.45 Housing. (a) Housing provided by the recipient. A recipient that provides housing to its nonhandicapped students shall provide comparable, convenient, and accessible housing to handicapped students...

  16. 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...

  17. 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...

  18. 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.

  19. 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 ...

  20. 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

  1. 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...

  2. 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.

  3. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

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

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and...... renal tubule and then discuss why not all gene defects that cause renal tubular acidosis are associated with hypercalciuria and nephrocalcinosis....

  4. Comparative aspects of calcium dynamics in calcified tissues in the goldfish Carassius auratus

    International Nuclear Information System (INIS)

    The comparative nature of calcium physiology in bone, scales and otoliths was studied in young goldfish, Carassius auratus. Net calcium uptake by the fish was estimated to be 143 μg/g body weight/day. Of that, 79 % was distributed in bone, 13 % in scales, 3.5 % in otoliths and 4.5 % in soft tissues. Scales showed the highest incorporation of 45Ca per mg-tissue weight after 1 or 2 days in 45Ca-containing water; bone came second and otoliths last. However, 35 days after transfer to non-radioactive water, the order of descending radioactivity had changed to otoliths, bone and scales, reflecting different rates of calcium turnover. In bone, prelabeled 45Ca activity increased for the first 2 days after transfer and then decreased gradually (biological half-life, Tsub(0.5) = 94 days). In otoliths, prelabeled radioactivity consistently increased for 35 days. Scales showed two phases of calcium turnover. They lost about 33 % of their prelabeled radioactivity during the first 7 days (Tsub(0.5) = 10.5 days) in non-radioactive water, but thereafter the rate of decrease slowed down greatly (Tsub(0.5) = 210 days). These two phases of calcium turnover were found in the osseous layer (including calcium crystals in the fibrillary plate) of scales, indicating the presence of physiologically labile as well as stable forms of calcium in the layer. (author)

  5. ATP stimulates calcium influx in primary astrocyte cultures

    International Nuclear Information System (INIS)

    The effect of ATP and other purines on 45Ca uptake was studied in primary cultures of rat astrocytes. Treatment of the cells with ATP for 1 to 30 min brought about an increase in cellular 45Ca. Stimulation of calcium influx by ATP was investigated using a 90 sec exposure to 45Ca and over a concentration range of 0.1 nM to 3 mM; a biphasic dose-response curve was obtained with EC50 values of 0.3 nM and 9 uM, indicating the presence of low and high affinity purinergic binding sites. Similar levels of 45Ca influx at 90 sec were observed with ATP, ADP and adenosine (all at 100 uM). Prior treatment of the cultures with LaCl3 blocked the purine-induced 45Ca influx. These findings indicate that one pathway for calcium entry in astrocytes involves purinergic receptor-operated, calcium channels

  6. 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

  7. 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

  8. 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...

  9. 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.

  10. Calcium diffusion through perineurium of frog sciatic nerve

    International Nuclear Information System (INIS)

    Calcium and sucrose permeabilities (PCa or Psucrose) were calculated from the fluxes of 45Ca and [3H]sucrose across perfused everted and normal configurations of the perineurial cylinder isolated from the frog sciatic nerve and from fluxes into an intact nerve segment bathed in Ringer. Mean PCa for influx across the isolated perineurium equaled 10.2 ± 0.6 x 10-7 cm/s compared with Psucrose = 7.4 ± 0.4 x 10-7 cm/s. For efflux, PCa = 27.5 ± 5.0 x 10-7 cm/s and Psucrose = 23.2 ± 4.7 x 10-7 cm/s. The mean ratio of PCa for efflux to PCa for influx was not significantly different from the flux ratio for sucrose. Asymmetrical fluxes across the perineurial cylinder were due presumably to bulk flow and resultant solvent drag out of the lumen caused by perfusion pressure. Calcium accumulated in the perineurial tissue in a saturable manner with a Km of 80 μM and a Bmax of 0.22 μmol/g wet wt. The half time for calcium exchange from the external medium to the nerve was calculated as 3 h. This long half time and the calcium-sequestering ability of the perineurium suggest that the perineurium can stabilize endoneurial calcium during transient changes in the calcium concentration of plasma

  11. 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...

  12. Voltage-dependent calcium channels in skeletal muscle transverse tubules. Measurements of calcium efflux in membrane vesicles

    International Nuclear Information System (INIS)

    Transverse tubule membranes isolated from rabbit skeletal muscle consist mainly of sealed vesicles that are oriented primarily inside out. These membranes contain a high density of binding sites for 1,4-dihydropyridine calcium channel antagonists. The presence of functional voltage-dependent calcium channels in these membranes has been demonstrated by their ability to mediate 45Ca2+ efflux in response to changes in membrane potential. Fluorescence changes of the voltage-sensitive dye, 3,3'-dipropyl-2,2'-thiadicarbocyanine, have shown that transverse tubule vesicles may generate and maintain membrane potentials in response to establishing potassium gradients across the membrane in the presence of valinomycin. A two-step procedure has been developed to measure voltage-dependent calcium fluxes. Vesicles loaded with 45Ca2+ are first diluted into a buffer designed to generate a membrane potential mimicking the resting state of the cell and to reduce the extravesicular Ca2+ to sub-micromolar levels. 45Ca2+ efflux is then measured upon subsequent depolarization. Flux responses are modulated with appropriate pharmacological specificity by 1,4-dihydropyridines and are inhibited by other calcium channel antagonists such as lanthanum and verapamil

  13. Effect of sepsis on calcium uptake and content in skeletal muscle and regulation in vitro by calcium of total and myofibrillar protein breakdown in control and septic muscle: Results from a preliminary study

    International Nuclear Information System (INIS)

    Because high calcium concentration in vitro stimulates muscle proteolysis, calcium has been implicated in the pathogenesis of increased muscle breakdown in different catabolic conditions. Protein breakdown in skeletal muscle is increased during sepsis, but the effect of sepsis on muscle calcium uptake and content is not known. In this study the influence of sepsis, induced in rats by cecal ligation and puncture, on muscle calcium uptake and content was studied. Sixteen hours after cecal ligation and puncture or sham operation, calcium content of the extensor digitorum longus (EDL) and soleus (SOL) muscles was determined with an atomic absorption spectrometer. Calcium uptake was measured in intact SOL muscles incubated in the presence of calcium 45 (45Ca) for between 1 and 120 minutes. Total and myofibrillar protein breakdown was determined in SOL muscles, incubated in the presence of different calcium concentrations (0; 2.5; 5.0 mmol/L), and measured as release into the incubation medium of tyrosine and 3-methylhistidine (3-MH), respectively. Calcium content was increased by 51% (p less than 0.001) during sepsis in SOL and by 10% (p less than 0.05) in EDL muscle. There was no difference in 45Ca uptake between control and septic muscles during the early phase (1 to 5 minutes) of incubation. During more extended incubation (30 to 120 minutes), muscles from septic rats took up significantly more 45Ca than control muscles (p less than 0.05). Tyrosine release by incubated SOL muscles from control and septic rats was increased when calcium was added to the incubation medium, and at a calcium concentration of 2.5 mmol/L, the increase in tyrosine release was greater in septic than in control muscle. Addition of calcium to the incubation medium did not affect 3-MH release in control or septic muscle

  14. 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...

  15. Vitamin D does not increase calcium absorption in young women: a randomized clinical trial.

    Science.gov (United States)

    Gallagher, J Christopher; Jindal, Prachi S; Smith, Lynette M

    2014-01-01

    It is commonly said that vitamin D should be used to increase calcium absorption. We tested this statement in a dose-response study of vitamin D on calcium absorption. A total of 198 white and African American women, aged 25 to 45 years, with vitamin D insufficiency, serum 25-hydroxyvitamin D (25OHD) ng/mL, were randomized in a double-blind study to vitamin D3 400, 800, 1600, 2400 IU, or placebo. A calcium supplement was given to increase mean calcium intake at baseline from 706 mg/d to 1031 mg/d. Calcium absorption was measured at baseline and after 12 months using a single isotope method with radiocalcium45 and 100 mg of calcium. Mean baseline serum 25OHD was 13.4 ng/mL (33.5 nmol/L) and increased to 40 ng/mL (100 nmol/L) on the highest dose of 2400 IU. Using a multivariate regression analysis with significant predictors, baseline absorption, calcium intake, and weight, there was no increase in 12-month calcium absorption compared with baseline on any dose of vitamin D in either whites or African Americans. There was no significant relationship between 12-month calcium absorption and final serum 25OHD. In an analysis of calcium absorption and serum 25OHD at baseline, serum 25OHD levels were divided into groups: 0 to 5, 6 to 10, 11 to 15, or 16 to 20 ng/mL. There was no evidence of a threshold decrease in calcium absorption or serum 1,25 dihydroxyvitamin D (1,25(OH)2 D) amongst the lowest groups. Vitamin D doses up to 2400 IU daily did not increase calcium absorption. No threshold level of serum 25OHD for calcium absorption was found at baseline or in the longitudinal study, suggesting that active transport of calcium is saturated at very low serum 25OHD levels ng/mL. There is no need to recommend vitamin D for increasing calcium absorption in normal subjects. Very efficient calcium absorption at very low levels of serum 25OHD explains why people do not develop osteomalacia provided that dietary intakes of calcium and phosphorus are adequate. PMID

  16. 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...

  17. 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.

  18. 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...

  19. 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.

  20. 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...

  1. 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...

  2. 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......

  3. 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.

  4. 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.

  5. Effect of ticlopidine ex vivo on platelet intracellular calcium mobilization

    Energy Technology Data Exchange (ETDEWEB)

    Derian, C.K.; Friedman, P.A.

    1988-04-01

    The antiplatelet compound ticlopidine exerts its potent inhibitory activity through an as yet undetermined mechanism(s). The goal of this study was to determine the effect, if any, of ticlopidine ex vivo on platelet calcium mobilization. Ticlopidine inhibited ADP-induced platelet aggregation by 50-80%. In the presence of 1 mM EGTA, ticlopidine inhibited ADP- and thrombin-stimulated increases in (Ca2+)i in fura-2 loaded platelets. We evaluated further the effect of ticlopidine on calcium mobilization by examining both agonist-stimulated formation of inositol trisphosphate in intact platelets and the ability of inositol trisphosphate to release /sup 45/Ca from intracellular sites in permeabilized cells. We show here that while ticlopidine significantly affected agonist-induced intracellular calcium mobilization in intact platelets, the drug was without effect on agonist-stimulated formation of inositol trisphosphate in intact platelets and on inositol trisphosphate-induced /sup 45/Ca release in saponin-permeabilized platelets. Our study demonstrates that ticlopidine exerts at least part of its effect via inhibition of intracellular calcium mobilization but that its site of action remains to be determined.

  6. 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 ...

  7. 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 ...

  8. 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)

  9. Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

    OpenAIRE

    Ganesan Lavanya; Josephraj Jegan

    2015-01-01

    This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study...

  10. 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...

  11. Role of calcium in the constriction of isolated cerebral arteries

    International Nuclear Information System (INIS)

    Calcium entry blockers (CEB) have been used in the experimental treatment or prevention of many cerebrovascular disorders including stroke, post-ischemic hypoperfusion after cardiac arrest, cerebral vasospasm after subarachnoid hemorrhage, and migraine headache. However, the mechanism of action of these drugs on the cerebral circulation is poorly understood. This study examined the effects of calcium antagonists, Ca2+-deficient solutions, and vasocostrictors on cerebrovascular tone and 45Ca fluxes, to determine the role of calcium in cerebral arterial constriction. A Scatchard plot of 45Ca binding to BMCA showed that Ca2+ was bound at either low or high affinity binding sties. The four vasoconstrictors (potassium, serotonin, PGF/sub 2 α/, or SQ-26,655) each increased low affinity 45Ca uptake into BMCA. The results demonstrate that: (1) Potassium and serotonin constrict BMCA mainly by promoting Ca2+ influx through CEB-sensitive channels; (2) PGF/sub 2 α/ and SQ-26,655 constrict BMCA in part by promoting Ca2+ influx through CEB-sensitive channels, and in part by releasing Ca2+ from depletable internal stores; (3) The major action of CEB on BMCA is to block vasoconstrictor-induced Ca2+ uptake through both potential-operated (K+-stimulated) and receptor-operated channels

  12. Early postischemic 45Ca accumulation in rat dentate hilus

    International Nuclear Information System (INIS)

    Several studies have found postischemic regional accumulation of calcium to be time-dependent and coincident with the progression of ischemic cell change. In the most vulnerable cells in the hippocampus one would therefore expect to find a primary and specific early uptake of calcium after ischemia. Autoradiograms of 45Ca and 3H-inulin distribution were investigated before and 1 h after 20 min ischemia in the rat hippocampus. Two different methodological approaches were used for administration of 45Ca: (a) administration via microdialysis probes, (b) intraventricular injection. During control conditions the 45Ca autoradiograms showed variations in distribution volume in accordance with 3H-inulin determination of extracellular space size. One hour after ischemia a massive accumulation of 45Ca was found in the dentate hilus. No change in the distribution pattern of 3H-inulin could be demonstrated 1 h after ischemia. We suggest that 45Ca accumulation in dentate hilus 1 h after ischemia is a result of increased Ca2+ uptake before irreversible cell damage occurs and is not due to passive influx of calcium across a leaky plasma membrane

  13. 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

  14. Calcium bioavailability of vegetarian diets in rats: potential application in a bioregenerative life-support system

    Science.gov (United States)

    Nickel, K. P.; Nielsen, S. S.; Smart, D. J.; Mitchell, C. A.; Belury, M. A.

    1997-01-01

    Calcium bioavailability of vegetarian diets containing various proportions of candidate crops for a controlled ecological life-support system (CELSS) was determined by femur 45Ca uptake. Three vegetarian diets and a control diet were labeled extrinsically with 45Ca and fed to 5-wk old male rats. A fifth group of rats fed an unlabeled control diet received an intraperitoneal (IP) injection of 45Ca. There was no significant difference in mean calcium absorption of vegetarian diets (90.80 +/- 5.23%) and control diet (87.85 +/- 5.25%) when calculated as the percent of an IP dose. The amounts of phytate, oxalate, and dietary fiber in the diets did not affect calcium absorption.

  15. Antibodies against the calcium-binding protein

    International Nuclear Information System (INIS)

    Plant microsomes contain a protein clearly related to a calcium-binding protein, calsequestrin, originally found in the sarcoplasmic reticulum of muscle cells, responsible for the rapid release and uptake of Ca2+ within the cells. The location and role of calsequestrin in plant cells is unknown. To generate monoclonal antibodies specific to plant calsequestrin, mice were immunized with a microsomal fraction from cultured cells of Streptanthus tortuosus (Brassicaceae). Two clones cross-reacted with one protein band with a molecular weight equal to that of calsequestrin (57 kilodaltons) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. This band is able to bind 45Ca2+ and can be recognized by a polyclonal antibody against the canine cardiac muscle calsequestrin. Rabbit skeletal muscle calsequestrin cross-reacted with the plant monoclonal antibodies. The plant monoclonal antibodies generated here are specific to calsequestrin protein

  16. 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.

  17. 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.

  18. Calcium uptake by cowpea as influenced by mycorrhizal colonization and water stress

    International Nuclear Information System (INIS)

    The role of vesicular-arbuscular mycorrhizal (VAM) colonization on calcium uptake was studied under different levels of moisture stress. Pots maintained at different moisture levels were given water containing known amount of radioactive calcium. The radioactivity in different parts of the plant was assessed 60 h after giving 45Ca to the soil. High 45 Ca activity was present in all parts of vesicular-arbuscular mycrrohizal (VAM) plants compared to non-mycorrhizal plants at all levels of moisture stress. (author). 14 refs., 1 tab

  19. Preparation of 45Ca(HDEHP)n and (CaH1502)2 samples for liquid scintillation counting, compared to 45caCl2 results

    International Nuclear Information System (INIS)

    A procedure for preparation of liquid scintillation counting organic samples of the Di-2-ethylhexyl phosphate calcium complex and the 2-ethylhexanoate calcium salt, labelled with 45Ca, is described. The chemical quench, the counting stability and spectral evolution of both compounds is studied in six scintillators,Toluene-alcohol, Dioxane-naphtalene, Hi safe II, Ultimate-Gold and Instagel, and compared to results obtained from a commercial solution of 4 5CaCl2. (Author) 7 refs

  20. Preparation of 45 Ca (HDEHP)n and (C8H15O2)2 samples for liquid scintillation counting, compared to 45CaCl2 results

    International Nuclear Information System (INIS)

    A procedure for preparation of liquid scintillation counting organic samples of the Di-2-ethylhexyl phosphate calcium complex and the 2-ethyhexanoate calcium salt, labelled with ''45 Ca, is described. The chemical quench, the counting stability and spectral evolution of both compounds is studied in six scintillators, Toluene, Toluene-alcohol, Dioxane-napthalhene, Hisafe II, Ultima-Gold and Instagel, and compared to results obtained from a commercial solution of ''45 CaCl2

  1. 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...

  2. Lipopolysaccharide (LPS)-mediated macrophage activation: the role of calcium in the generation of tumoricidal activity

    Energy Technology Data Exchange (ETDEWEB)

    Drysdale, B.E.; Shin, H.S.

    1986-03-01

    As the authors reported, calcium ionophore, A23187, activates macrophages (M theta) for tumor cell killing and the activated M theta produce a soluble cytotoxic factor (M theta-CF) that is similar if not identical to tumor necrosis factor. Based on these observations they have investigated whether calcium is involved in the activation mediated by another potent M theta activator, LPS. The authors have shown that A23187 caused uptake of extracellular /sup 45/Ca/sup + +/ but LPS did not. They have examined the effect of depleting extracellular calcium by using medium containing no added calcium containing 1.0 mM EGTA. In no case did depletion result in decreased M theta-CF production by the M theta activated with LPS. Measurements using the fluorescent, intracellular calcium indicator, Quin 2 have also been performed. While ionomycin, caused a rapid change in the Quin-2 signal, LPS at a concentration even in excess of that required to activate the M theta caused no change in the signal. When high doses of Quin 2 or another intracellular chelator, 8-(diethylaminol-octyl-3,4,5-trimethoxybenzoate, were used to treat M theta, M theta-CF production decreased and cytotoxic activity was impaired. These data indicate that one or more of the processes involved in M theta-CF production does require calcium, but that activation mediated by LPS occurs without the influx of extracellular calcium or redistribution of intracellular calcium.

  3. Characterization of transport of calcium by microsomal membranes from roots maize

    Energy Technology Data Exchange (ETDEWEB)

    Vaughan, M.A.

    1985-01-01

    This study investigates calcium transport by membranes of roots of maize isolated by differential centrifugation. The preparation was determined to be enriched in plasma membrane using market enzyme and electron microscopy. Using the /sup 45/Ca filtration technique and liquid scintillation counting, vesicular calcium uptake was shown to be stimulated by added calmodulin and specific for and dependent on ATP. Conditions for maximal calcium accumulation were found to be 30 min incubation in the presence of 5 mM ATP, 5 mM MgCl/sub 2/, 50 ..mu..M CaCl/sub 2/, at 23/sup 0/C, and at pH 6.5. Calcium uptake was inhibited by the ionophores A23187, X-537A, and ionomycin. Sodium fluoride, ruthenium red, and p-chloromercuribenzoate completely inhibited transport: diamide and vanadate produced slight inhibition; caffeine, caffeic acid, oligomycin, and ouabain produced little or no inhibition. Chlorpromazine, W7, trifluoperazine, and R 24 571 inhibit calcium uptake irrespective of added calmodulin, while W5 showed little effect on uptake. Verapamil, nifedipine, cinnarizine, flunarizine, lidoflazine, and diltiazem decreased calcium uptake by 17%-50%. Electron microscopic localization of calcium by pyroantimonate showed vesicles incubated with calmodulin and ATP showed the greatest amount of precipitate. These results suggest that these vesicles accumulate calcium in an ATP-dependent, calmodulin-stimulated manner.

  4. 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

  5. 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...

  6. 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

  7. Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels

    Directory of Open Access Journals (Sweden)

    S.A. Gomes

    2004-09-01

    Full Text Available the response to an oral calcium load test was assessed in 17 hypercalciuric nephrolithiasis patients who presented elevated parathyroid hormone (PTH irrespective of the ionized calcium (sCa2+ levels. Blood samples were collected at baseline (0 min and at 60 and 180 min after 1 g calcium load for serum PTH, total calcium, sCa2+, and 1.25(OH2D3 determinations. According to the sCa2+ level at baseline, patients were classified as normocalcemic (N = 9 or hypercalcemic (N = 8. Six healthy subjects were also evaluated as controls. Bone mineral density was reduced in 14/17 patients. In the normocalcemic group, mean PTH levels at 0, 60 and 180 min (95 ± 76, 56 ± 40, 57 ± 45 pg/ml, respectively did not differ from the hypercalcemic group (130 ± 75, 68 ± 35, 80 ± 33 pg/ml but were significantly higher compared to healthy subjects despite a similar elevation in sCa2+ after 60 and 180 min vs baseline in all 3 groups. Mean total calcium and 1.25(OH2D3 were similar in the 3 groups. Additionally, we observed that 5 of 9 normocalcemic patients presented a significantly higher concentration-time curve for serum PTH (AUC0',60',180' than the other 4 patients and the healthy subjects, suggesting a primary parathyroid dysfunction. These data suggest that the individual response to an oral calcium load test may be a valuable dynamic tool to disclose a subtle primary hyperparathyroidism in patients with high PTH and fluctuating sCa2+ levels, avoiding repeated measurements of both parameters.

  8. Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels

    Directory of Open Access Journals (Sweden)

    Gomes S.A.

    2004-01-01

    Full Text Available the response to an oral calcium load test was assessed in 17 hypercalciuric nephrolithiasis patients who presented elevated parathyroid hormone (PTH irrespective of the ionized calcium (sCa2+ levels. Blood samples were collected at baseline (0 min and at 60 and 180 min after 1 g calcium load for serum PTH, total calcium, sCa2+, and 1.25(OH2D3 determinations. According to the sCa2+ level at baseline, patients were classified as normocalcemic (N = 9 or hypercalcemic (N = 8. Six healthy subjects were also evaluated as controls. Bone mineral density was reduced in 14/17 patients. In the normocalcemic group, mean PTH levels at 0, 60 and 180 min (95 ± 76, 56 ± 40, 57 ± 45 pg/ml, respectively did not differ from the hypercalcemic group (130 ± 75, 68 ± 35, 80 ± 33 pg/ml but were significantly higher compared to healthy subjects despite a similar elevation in sCa2+ after 60 and 180 min vs baseline in all 3 groups. Mean total calcium and 1.25(OH2D3 were similar in the 3 groups. Additionally, we observed that 5 of 9 normocalcemic patients presented a significantly higher concentration-time curve for serum PTH (AUC0',60',180' than the other 4 patients and the healthy subjects, suggesting a primary parathyroid dysfunction. These data suggest that the individual response to an oral calcium load test may be a valuable dynamic tool to disclose a subtle primary hyperparathyroidism in patients with high PTH and fluctuating sCa2+ levels, avoiding repeated measurements of both parameters.

  9. Effects of gastrin on calcium homeostasis in chickens

    International Nuclear Information System (INIS)

    As in the rat, gastrin and an extract of the acid-producing part of the stomach (proventriculus) were found to lower the blood Ca2+ concentration in the chicken. Furthermore, gastrin enhanced the uptake of 45Ca into the femur. It has been suggested previously that gastrin causes hypocalcemia in the rat by releasing gastrocalcin, a hypothetical hormone thought to reside in the acid-producing part of the stomach. The results of the present study in the chicken are in agreement with this concept. Not only exogenous, but also endogenous gastrin lowered blood calcium levels. Thus, the serum gastrin concentration was increased in response to ranitidine-evoked blockade of the gastric acid output; the rise in gastrin was associated with a transient drop in blood calcium. Also, food intake produced a rise in the serum gastrin concentration and a transient drop in blood calcium. However, injection of ranitidine or food intake in proventriclectomized (acid-producing part of the stomach extirpated) chickens failed to lower blood calcium, supporting the view that the gastrin-evoked hypocalcemia depends upon an agent in the gastric (proventriculus) mucosa. The authors suggest that endogenous and exogenous gastrin evoke hypocalcemia in the chicken by the same mechanism as that which has been postulated in the rat, i.e. by mobilization of the candidate hormone gastrocalcin from endocrine cells in the acid-producing gastric mucosa

  10. Hydrolytically stable titanium-45

    DEFF Research Database (Denmark)

    Severin, Gregory; Fonslet, Jesper; Zhuravlev, Fedor

    2014-01-01

    . The high cross-section and production rates on an unenriched metal foil target contribute to make 45Ti an ideal PET radionuclide. In order to bring 45Ti to even a preclinical plat-form, the hydrolytic instability of aqueous Ti(IV) needs to be addressed. Recently, the groups of Edit Tshuva (Hebrew......, similar to ion-pairing, and eluted with isopropanol. iv. 45Ti was extracted onto a polystyrene based 1,3 diol resin (RAPP polymers) and labeling commenced on the column. Radiolabeling was slightly different in each condition, but in general the salan and dipic ligands were added to the 45Ti in pyridine...

  11. "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...

  12. 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...

  13. 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 ...

  14. 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

  15. 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

  16. Red blood cell calcium homeostasis in patients with end-stage renal disease

    International Nuclear Information System (INIS)

    Low cell calcium level is essential for preservation of red blood cell (RBC) membrane deformability and survival. RBCs from patients with end-stage renal disease (ESRD) demonstrate reduction in membrane deformability, possibly as a result of increased RBC cellular calcium level. To evaluate calcium homeostasis in RBCs from patients with ESRD, we measured cell calcium level, basal and calmodulin-stimulated calcium-stimulated Mg-dependent ATPase (CaATPase) activity, and calcium 45 efflux were measured before and after hemodialysis. The in vitro effect of uremic plasma and of urea on CaATPase activity of normal RBCs was tested, and 45Ca influx into RBCs of patients undergoing hemodialysis also was determined. A morphologic evaluation of red cells from patients with ESRD was performed with a scanning electron microscope. RBC calcium level in patients (mean +/- SEM 21.2 +/- 2.8 mumol/L of cells; n = 28) was higher than in controls (4.9 +/- 0.3 mumol/L of cells; n = 24; p less than 0.001). Hemodialysis had no effect on cell calcium level. Both basal and calmodulin-stimulated RBC CaATPase activities in patients with ESRD (n = 9) were reduced by approximately 50% (p less than 0.01), but after hemodialysis, enzyme activity returned to normal. 45Ca efflux from calcium-loaded cells, which was 2574.0 +/- 217.0 mumol/L of cells per 0.5 hours before hemodialysis, increased to 3140.7 +/- 206.8 mumol/L of cells per 0.5 hours after hemodialysis (p less than 0.005). In vitro incubation of normal RBCs with uremic plasma depressed CaATPase activity, but incubation with urea had no effect. RBCs of patients with ESRD revealed increased 45Ca influx, 7.63 +/- 1.15 mumol/L of cells per hour versus 4.61 +/- 0.39 mumol/L of cells per hour (p less than 0.025). RBCs of patients revealed a high incidence of spherocytosis and echynocytosis, which correlated with a high cell calcium level (r = 0.894, p less than 0.01)

  17. 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

  18. 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

  19. Heat-resistant mechanism of transgenic rape by 45Ca isotope tracer

    International Nuclear Information System (INIS)

    The Ca2+ uptake differences of the rape with heat-resistant gene and the general rape were investigated by 45Ca isotope tracer. The results showed that the rape with heat-resistant gene can strengthen the regulation of calcium absorption. The calcium regulation ability of the heat-resistant genes may be able to play in the rape aspect of the mechanism of resistance. (authors)

  20. 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...

  1. 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

  2. Calcium handling by platelets from normal and malignant hyperthermia-susceptible pigs

    International Nuclear Information System (INIS)

    Platelets from normal and malignant hyperthermia (MH)-susceptible pigs were evaluated for differences in 45calcium uptake in the absence or presence of caffeine, halothane, or halothane and caffeine together. There were no statistically significant differences in basal or halothane-inhibited calcium uptake by platelets from either source. There was a small statistically significant difference in calcium uptake between platelets from normal and MH-susceptible pigs in the presence of 16 mM caffeine and 0.5% halothane. Calcium uptake by platelets from one pedigree of MH-susceptible pigs were stimulated in a concentration-dependent manner by caffeine. These data suggest that exposure of platelets to caffeine may have potential for identifying MH-susceptibility

  3. 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

  4. Effect of fasting and parathyroid hormone injection on plasma 45Ca concentrations in rats

    International Nuclear Information System (INIS)

    Young male rats were administered 45Ca 5 days to 2 weeks prior to use. All rats were either parathyroidectomized (PTX) or thyroparathyroidectomized (TPTX) and given several days to recover from surgery. The first group of rats were maintained on a 12 h dark-fed and 12 h light-fasted daily cycle. The remainder of the rats were used for parathyroid hormone (PTH) studies (0.1-0.6 U/g body weight) following which blood samples were obtained from the tail for 1 to 6 h. Two groups of these rats were bilaterally nephrectomized 18 h before PTH injection. Two contrasting results were obtained: in PTX (or TPTX) rats maintained on the closely regulated food and light regime, plasma 45Ca concentrations rose markedly each day at the start of the fasting period and then fell slowly. Total plasma calcium values fell throughout the fasting period. A similar rise and fall was also observed in 45Ca values of rats experimentally fasted after being maintained with food continuously available. In contrast, in all PTX or TPTX rats, PTH injection was followed by an equal rise in both plasma calcium and 45Ca values so that for the first few hours plasma 45Ca specific activity was unchanged. These data are consistent with the concept of a bone fluid compartment (BFC) separated by a cellular interface from the primary extracellular fluid space (ECF). It is postulated that through this cellular interface calcium is actively 'pumped' from the BFC to the ECF. The rise in plama 45Ca values at the start of fasting is explained on the basis of decreased entry of stable calcium from the gastrointestinal tract and a continued movement of calcium and 45Ca from the BFC to the ECF. The concomitant increase in plasma calcium and 45Ca during the first few hours after PTH injection is explained by a rapid action of PTH to increase the rate of calcium movement from BFC to ECF by its action at the cellular interface, without altering 45Ca specific activity until such time as dissolution of bone crystals is

  5. 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.

  6. Phorbol ester stimulates calcium sequestration in saponized human platelets

    International Nuclear Information System (INIS)

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

  7. Phorbol ester stimulates calcium sequestration in saponized human platelets

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K.; Nachmias, V.T.

    1987-11-25

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

  8. Contribution to the study of calcium metabolism in the deficiency of testosterone

    International Nuclear Information System (INIS)

    Kinetic parameters of calcium mobilization in rats were determined to estimate the role of testosterone in the metabolism of this ion. Calcium multicompartimental theory was combined to and used in measurements of metabolic balance (for 45CaCl2 or 40CaCl2). Three groups of 60 day old rats were used: G I-control; G II-castrated; G III-castrated and treated with testosterone propionate. Data were obtained from measurements of Ca++ in samples of plasma, feces and urine. Balance studies suggest that calcium level in blood plasma remained constant in all groups, the increase of bone reabsorption in groups II and III being counterbalanced by the elevation of the urinary excrection. This result implies the equilibrium occurring at renal level. Intestinal calcium absorption remained the same in the three groups of animals, indicating that testosterone has no consistent effect at intestinal level. The increase of total calcium in feces of groups II and III arises from a great endogenous secretion. A significant negative balance of calcium was also observed in these groups. This fact permits the conclusion that in the absence of testosterone the organism doesn't retain calcium efficiently. (M.A.)

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

    Directory of Open Access Journals (Sweden)

    Fateme Rostami

    2012-07-01

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

  10. Cytoplasmic calcium levels in protoplasts from the cap and elongation zone of maize roots

    Science.gov (United States)

    Kiss, H. G.; Evans, M. L.; Johnson, J. D.

    1991-01-01

    Calcium has been implicated as a key component in the signal transduction process of root gravitropism. We measured cytoplasmic free calcium in protoplasts isolated from the elongation zone and cap of primary roots of light-grown, vertically oriented seedlings of Zea mays L. Protoplasts were loaded with the penta-potassium salts of fura-2 and indo-1 by incubation in acidic solutions of these calcium indicators. Loading increased with decreasing pH but the pH dependence was stronger for indo-1 than for fura-2. In the case of fura-2, loading was enhanced only at the lowest pH (4.5) tested. Dyes loaded in this manner were distributed predominantly in the cytoplasm as indicated by fluorescence patterns. As an alternative method of loading, protoplasts were incubated with the acetoxymethylesters of fura-2 and indo-1. Protoplasts loaded by this method exhibited fluorescence both in the cytoplasm and in association with various organelles. Cytoplasmic calcium levels measured using spectrofluorometry, were found to be 160 +/- 40 nM and 257 +/- 27 nM, respectively, in populations of protoplasts from the root cap and elongation zone. Cytoplasmic free calcium did not increase upon addition of calcium to the incubation medium, indicating that the passive permeability to calcium was low.

  11. Calcium absorbability from milk products, an imitation milk, and calcium carbonate

    International Nuclear Information System (INIS)

    Whole milk, chocolate milk, yogurt, imitation milk (prepared from dairy and nondairy products), cheese, and calcium carbonate were labeled with 45Ca and administered as a series of test meals to 10 healthy postmenopausal women. Carrier Ca content of the test meals was held constant at 250 mg and subjects fasted before each meal. The absorbability of Ca from the six sources was compared by measuring fractional absorption by the double isotope method. The mean absorption values for all six sources were tightly clustered between 21 and 26% and none was significantly different from the others using one-way analysis of variance. We conclude that none of the sources was significantly superior or inferior to the others

  12. 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.)

  13. 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

  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. Myo-Inositol trisphosphate mobilizes calcium from fusogenic carrot (Daucus carota L.) protoplasts

    International Nuclear Information System (INIS)

    To determine whether or not inositol trisphosphate (IP3) mobilizes calcium in higher plant cells; they investigated the effect of IP3 on Ca2+ fluxes in fusogenic carrot (Daucus carota L.) protoplasts. The protoplasts were incubated in 45Ca2+-containing medium and the 45Ca2+ associated with the protoplasts was monitored with time. Addition of IP3 (20 micromolar) caused a 17% net loss of the accumulated 45Ca2+ within 4 minutes. There was a reuptake of 45Ca2+ and the protoplasts recovered to their initial value by 10 minutes. Phytic acid (IP6), also stimulated 45Ca2+ efflux from the protoplasts. Both the IP3- and the IP6-induced 45Ca2+ efflux were inhibited by the calmodulin antagonist, trifluoperazine

  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. A COMPARATIVE STUDY OF EFFICACY OF CALCIUM + VITAMI N D3 AND CALCIUM + VITAMIN D3 + VITAMIN K2 IN PREVENTION OF OSTEOPOROSIS IN POSTMENOPAUSAL OSTEOPENIC WOMEN WHO ARE ADOPTING A SEDENTARY PATTERN OF LIFE STYLE

    OpenAIRE

    Verma; Gandhi,, D

    2013-01-01

    ABSTRACT: OBJECTIVE:- The aim of the study was to determine the efficacy of combination of vitamin K2+ vitamin D3+calcium in prevention of ost eoporosis in osteopenic postmenopausal women . MATERIALS AND METHODS: This study included 60 postmenopausal osteopenic w omen. They were divided in two groups one group were admi nistered 1gm calcium+ vitamin D3 1 mcg /day and other group were administered 1gm calcium+ vita min D3 1mcg+vitamin K2 45mg/day. All the ...

  1. 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…

  2. 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

  3. Effects of protein incorporation on calcium phosphate coating

    OpenAIRE

    Leonor, I. B.; C.M. Alves; Azevedo, Helena S.; Reis, R.L.

    2009-01-01

    The incorporation of proteins into calcium phosphate (Ca–P) coatings is expected to alter their properties. The aim of this work is, therefore, to study the effect of protein concentration on the formation of Ca–P film. A biodegradable blend of corn starch/ethylene vinyl alcohol (SEVA-C) was used as substrate and bioactive glass (45S5 Bioglass®) was used as a nucleating agent. Bovine serum albumin (BSA) and α-amylase were added, separately, at a concentration of 0.5, 1, and 5 mg/mLto simulate...

  4. 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)....

  5. 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)....

  6. 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)....

  7. 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....

  8. 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....

  9. 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,...

  10. 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....

  11. 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....

  12. 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)...

  13. 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....

  14. 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

  15. Location and nature of calcium-binding sites in salivary acidic proline-rich phosphoproteins

    International Nuclear Information System (INIS)

    The location of the calcium-binding sites in the human acidic proline-rich proteins, salivary proteins A and C, was determined by equilibrium dialysis of the tryptic peptides with buffers containing 45Ca. All the calcium-binding sites are located in the NH2-terminal tryptic peptide (TX peptide). The nature of the calcium binding sites in the TX peptide and native salivary proteins A and C, as well as dephosphorylated proteins was compared. Two types of sites can be distinguished in peptide TX. Type I sites have an apparent dissociation constant (K) of 38 μM and are responsible for the binding of 2.6 mol of Ca/mol of peptide. The corresponding figures for Type II sites are 780 μM and 5.3 mol of Ca/mol of peptide. In the native proteins, the amount of calcium bound at the type II sites decreases to 3.9 mol of Ca/mol of proteins A and C and K increases to 1100 μM. The amount of calcium bound at type I sites decreases to 1.5 mol/mol of protein A and 0.6 mol/mol of protein C, but there is no change in K. Dephosphorylation affects the calcium binding at both types of sites. The experiments indicate that the COOH-terminal parts of the native proteins affect the number and the nature of the protein calcium-binding sites. Proton and phosphorous NMR data demonstrate that β-COOH in aspartic acid, as well as phosphoserine, are part of the calcium-binding sites. The difference in calcium binding to salivary proteins A and C may be due at least partially to differences in the environment of one or more aspartic acids

  16. Location and nature of calcium-binding sites in salivary acidic proline-rich phosphoproteins

    Energy Technology Data Exchange (ETDEWEB)

    Bennick, A. (Univ. of Toronto, Ontario); McLaughlin, A.C.; Grey, A.A.; Madapallimattam, G.

    1981-05-25

    The location of the calcium-binding sites in the human acidic proline-rich proteins, salivary proteins A and C, was determined by equilibrium dialysis of the tryptic peptides with buffers containing /sup 45/Ca. All the calcium-binding sites are located in the NH/sub 2/-terminal tryptic peptide (TX peptide). The nature of the calcium binding sites in the TX peptide and native salivary proteins A and C, as well as dephosphorylated proteins was compared. Two types of sites can be distinguished in peptide TX. Type I sites have an apparent dissociation constant (K) of 38 ..mu..M and are responsible for the binding of 2.6 mol of Ca/mol of peptide. The corresponding figures for Type II sites are 780 ..mu..M and 5.3 mol of Ca/mol of peptide. In the native proteins, the amount of calcium bound at the type II sites decreases to 3.9 mol of Ca/mol of proteins A and C and K increases to 1100 ..mu..M. The amount of calcium bound at type I sites decreases to 1.5 mol/mol of protein A and 0.6 mol/mol of protein C, but there is no change in K. Dephosphorylation affects the calcium binding at both types of sites. The experiments indicate that the COOH-terminal parts of the native proteins affect the number and the nature of the protein calcium-binding sites. Proton and phosphorous NMR data demonstrate that ..beta..-COOH in aspartic acid, as well as phosphoserine, are part of the calcium-binding sites. The difference in calcium binding to salivary proteins A and C may be due at least partially to differences in the environment of one or more aspartic acids.

  17. Use of digitonin permeabilization for characterization of calcium incorporated into β cells in response to glucose

    International Nuclear Information System (INIS)

    β cell-rich pancreatic islets were used to characterize 45Ca uptake into pools with different sensitivities to permeabilization with digitonin. The plasma and secretory granule membranes were among the membranes most sensitive to digitonin treatment whereas the mitochondria were more resistant. Most of the 45Ca incorporated in response to glucose was found in a fraction released after exposure to a high concentration of digitonin. The results suggest that glucose promotes active sequestration of calcium in mitochondria and that the uptake of 45Ca in the secretory granules in secondary to a raised cytosolic Ca2+ activity. (author)

  18. 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...

  19. 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...

  20. 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 ...

  1. Multiple calcium channels in synaptosomes: voltage dependence of 1,4-dihydropyridine binding and effects on function

    International Nuclear Information System (INIS)

    The voltage dependence of binding of the calcium channel antagonist, (+)-(3H]PN200-110, to rat brain synaptosomes and the effects of dihydropyridines on 45Ca2+ uptake have been investigated. Under nondepolarizing conditions (+)-(3H)PN200-110 binds to a single class of sites with a K/sub d/ of 0.07 nM and a binding capacity of 182 fmol/mg of protein. When the synaptosomal membrane potential was dissipated either by osmotic lysis of the synaptosomes or by depolarization induced by raising the external K+ concentration, there was a decrease in affinity with no change in the number of sites. The effects of calcium channel ligands on 45Ca2+ uptake by synaptosomes have been measured as a function of external potassium concentration, i.e., membrane potential. Depolarization led to a rapid influx of 45Ca2+ whose magnitude was voltage-dependent. Verapamil almost completely inhibited calcium uptake at all potassium concentrations studies. In contrast, the effects of dihydropyridines (2 μM) appear to be voltage-sensitive. At relatively low levels of depolarization nitrendipine and PN200-110 completely inhibited 45Ca2+ influx, whereas the agonist Bay K8644 slightly potentiated the response. At higher K+ concentrations an additional dihydropyridine-insensitive component of calcium uptake was observed. These results provide evidence for the presence of dihydropyridine-sensitive calcium channels in synaptosomes which may be activated under conditions of partial depolarization

  2. 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.

  3. 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.

  4. 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).

  5. Quantitative electron microscopical autoradiography of calcium during dentinogenesis

    International Nuclear Information System (INIS)

    45Ca migration from the dental papilla and the odontablasts towards predentin and dentin has been studied through electron microscopical autoradiography in toothgerms of newborn cats. A quantitative procedure was applied to the study of the 45Ca migration in dentinogenesis. Two pathways of almost identical importance have been demonstrated. The direct pathway followed the intercellular spaces of the dental papilla and of the odontoblasts and reached the dentin via predentin. The second road, after passage through the intercellular spaces of the dental papilla, consisted of an intracellular migration through the odontoblast. The mitochondria and the golgi apparatus were progressively the most labelet at 5 min., 30 min. and 1 h. after intravenous injection. The calcium diffused into the odontablastic process without being associated with the dense granule. At 6 hours, maximum radioactivity was observed in the intertubular dentin. (auth.)

  6. Calcium-antagonists and islet function. Pt. 5

    International Nuclear Information System (INIS)

    R33711, a new drug with presumed potent calcium-antagonistic property, was found to suppress the insulinotropic action of glucose und gliclazide but not that of theophylline. A 0.2 μM concentration of R33711 was sufficient to abolish glucose-induced insulin release. At this concentration, R33711 inhibited the net uptake of 45Ca2+ by isolated islets, whether in the absence or presence of either glucose or sulfonylurea. In the isolated islets, R33711 failed to affect the glucose-stimulated production of lactate, the rate of 45Ca2+ efflux, the inhibitory action of glucose upon such an efflux and its increase in response to theophylline. These data are compatible with the view that R33711 inhibits entry of Ca2+ into the B-cell and that integrity of such an inward cationic movement usually plays a permissive role in the maintenance of the Ca2+-dependent insulin secretory process. (orig.)

  7. 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.

  8. 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.

  9. Precipitation in a lead calcium tin anode

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico); Camurri, Carlos G., E-mail: ccamurri@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Carrasco, Claudia A., E-mail: ccarrascoc@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-02-15

    Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.

  10. Precipitation in a lead calcium tin anode

    International Nuclear Information System (INIS)

    Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 °C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn3 particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: ► The distance between precipitates in a lead alloy is recorded. ► The relationship between the distance and the cooling rate is established. ► It is found that the strengthening of the alloy depends on the distance between precipitates.

  11. IgE receptor-activated calcium permeability pathway in rat basophilic leukemia cells

    International Nuclear Information System (INIS)

    When antigen-stimulated 45Ca uptake is measured in RBL cells loaded with > 3 mM quin2, re-extrusion of 45Ca is minimized and the initial rate of 45Ca uptake reflects the true unidirectional influx of Ca. This influx correlates more closely with secretion than with the number of IgE receptors aggregated by antigen. The antigen-induced permeability pathway is saturable, having a Km of about 0.7 mM and a Vmax of 0.9 nmol Ca/106 cells/min and it persists for at least an hour provided that receptor aggregation is maintained. The negatively charged fluorescent probe bis-oxonol is insensitive to changes in the mitochondrial membrane potential and is, therefore, a useful plasma membrane potential indicator. Antigen-stimulation of RBL cells equilibrated with bis-oxonol causes a rapid depolarization that peaks within 2-3 minutes and persists until receptor aggregates are disrupted. Antigen-induced depolarization is seen in the absence of extracellular calcium, but is almost completely abolished when both sodium and calcium are replaced by glucose. Addition of calcium restores this response even when sodium is absent. This suggests that the IgE receptor-activated permeability pathway has a similar conductance for sodium and calcium ions

  12. Gallium increases bone calcium and crystallite perfection of hydroxyapatite.

    Science.gov (United States)

    Bockman, R S; Boskey, A L; Blumenthal, N C; Alcock, N W; Warrell, R P

    1986-12-01

    Gallium, a group IIIa metal, is known to interact with hydroxyapatite as well as the cellular components of bone. In recent studies we have found gallium to be a potent inhibitor of bone resorption that is clinically effective in controlling cancer-related hypercalcemia as well as the accelerated bone resorption associated with bone metastases. To begin to elucidate gallium's mechanism of action we have examined its effects on bone mineral properties. After short-term (14 days) administration to rats, gallium nitrate produced measurable changes in bone mineral properties. Using atomic absorption spectroscopy, low levels of gallium were noted to preferentially accumulate in regions of active bone formation, 0.54 +/- .07 microgram/mg bone in the metaphyses versus 0.21 +/- .03 microgram/mg bone in the diaphyses, P less than 0.001. The bones of treated animals had increased calcium content measured spectrophotometrically. Rats injected with radiolabeled calcium during gallium treatment had greater 45-calcium content compared to control animals. By wide-angle X-ray analyses, larger and/or more perfect hydroxyapatite was observed. The combined effects of gallium on bone cell function and bone mineral may explain its clinical efficacy in blocking accelerated bone resorption. PMID:3026592

  13. Calcium Carbonate versus Sevelamer Hydrochloride as Phosphate Binders after Long-Term Disease Progression in 5/6 Nephrectomized Rats

    Directory of Open Access Journals (Sweden)

    Suvi Törmänen

    2014-01-01

    Full Text Available Our aim was to compare the effects of calcium carbonate and sevelamer-HCl treatments on calcium-phosphate metabolism and renal function in 5/6 nephrectomized (NX rats so that long-term disease progression preceded the treatment. After 15-week progression, calcium carbonate (3.0%, sevelamer-HCl (3.0%, or control diets (0.3% calcium were given for 9 weeks. Subtotal nephrectomy reduced creatinine clearance (−40%, plasma calcidiol (−25%, and calcitriol (−70% and increased phosphate (+37%, parathyroid hormone (PTH (11-fold, and fibroblast growth factor-23 (FGF-23 (4-fold. In NX rats, calcium carbonate diet increased plasma (+20% and urinary calcium (6-fold, reduced plasma phosphate (−50% and calcidiol (−30%, decreased creatinine clearance (−35% and FGF 23 (−85%, and suppressed PTH without influencing blood pH. In NX rats, sevelamer-HCl increased urinary calcium (4-fold and decreased creatinine clearance (−45%, PTH (−75%, blood pH (by 0.20 units, plasma calcidiol (−40%, and calcitriol (−65%. Plasma phosphate and FGF-23 were unchanged. In conclusion, when initiated after long-term progression of experimental renal insufficiency, calcium carbonate diet reduced plasma phosphate and FGF-23 while sevelamer-HCl did not. The former induced hypercalcemia, the latter induced acidosis, while both treatments reduced vitamin D metabolites and deteriorated renal function. Thus, delayed initiation influences the effects of these phosphate binders in remnant kidney rats.

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

    International Nuclear Information System (INIS)

    Patients with acute vitiligo have low epidermal catalase expression/activities and accumulate 10-3 M H2O2. One consequence of this severe oxidative stress is an altered calcium homeostasis in epidermal keratinocytes and melanocytes. Here, we show decreased epidermal calmodulin expression in acute vitiligo. Since 10-3M H2O2 oxidises methionine and tryptophan residues in proteins, we examined calcium binding to calmodulin in the presence and absence of H2O2 utilising 45calcium. The results showed that all four calcium atoms exchanged per molecule of calmodulin. Since oxidised calmodulin looses its ability to activate calcium ATPase, enzyme activities were followed in full skin biopsies from lesional skin of patients with acute vitiligo (n = 6) and healthy controls (n = 6). The results yielded a 4-fold decrease of ATPase activities in the patients. Computer simulation of native and oxidised calmodulin confirmed the loss of all four calcium ions from their specific EF-hand domains. Taken together H2O2-mediated oxidation affects calcium binding in calmodulin leading to perturbed calcium homeostasis and perturbed L-phenylalanine-uptake in the epidermis of acute vitiligo

  15. [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

  16. 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....

  17. Calcium-activated butyrylcholinesterase in human skin protects acetylcholinesterase against suicide inhibition by neurotoxic organophosphates

    International Nuclear Information System (INIS)

    The human epidermis holds an autocrine acetylcholine production and degradation including functioning membrane integrated and cytosolic butyrylcholinesterase (BuchE). Here we show that BuchE activities increase 9-fold in the presence of calcium (0.5 x 10-3M) via a specific EF-hand calcium binding site, whereas acetylcholinesterase (AchE) is not affected. 45Calcium labelling and computer simulation confirmed the presence of one EF-hand binding site per subunit which is disrupted by H2O2-mediated oxidation. Moreover, we confirmed the faster hydrolysis by calcium-activated BuchE using the neurotoxic organophosphate O-ethyl-O-(4-nitrophenyl)-phenylphosphonothioate (EPN). Considering the large size of the human skin with 1.8 m2 surface area with its calcium gradient in the 10-3M range, our results implicate calcium-activated BuchE as a major protective mechanism against suicide inhibition of AchE by organophosphates in this non-neuronal tissue

  18. EFFECT OF PH AND TIME ON CALCIUM RELEASE FROM SOUND ENAMEL: AN ATOMIC SPECTROMETRIC ANALYSIS

    Directory of Open Access Journals (Sweden)

    Shetty Shishir

    2013-06-01

    Full Text Available Dental Caries is a disease of great concern which affects people of all races in all places, the exact etiology of caries though unknown; it is well established that the release of calcium and phosphate from hydroxyapatite crystal is due to decreased pH of saliva. However the relationship between calcium release, pH and time is not well documented.The present study was designed to assess the calcium release from intact enamel when subjected to different pH at different time intervals. The enamel samples were subjected to acid challenge using Acetate buffer of pH of 3.5, 4, 4.5, 5, 5.5, 6 and 6.5 and buffer solution were analyzed for calcium release at specific time intervals for each pH using atomic absorption spectrometry. The results show that the rate of calcium release significantly increased from pH 5.0 to 3.5, however the calcium release was very little in pH 5.5 to 6.5. From the observations made from this study we can conclude that sound enamel is resistant to acid attack between pH of 5 to 5.5 and Time plays an important role in the reaction of enamel to acid.

  19. 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

  20. 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...

  1. 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...

  2. Calcium and available phosphorus levels for laying hens in second production cycle

    OpenAIRE

    K Pelicia; EA Garcia; ABG Faitarone; de Silva AP; DA Berto; AB Molino; F Vercese

    2009-01-01

    This experiment studied the effect of four calcium (3.0, 3.5, 4.0, and 4.5%) and four available phosphorus levels (0.25, 0.30, 0.35, and 0.40%) in the diet of semi-heavy commercial layers after molting. Hisex Brown® layers between 90 and 108 weeks of age were distributed in a completely randomized experimental design with a 4x4 factorial arrangement with 16 treatments of five replicates of eight birds each. mortality, egg production, feed intake, egg mass, average egg weight, calcium and phos...

  3. Contribution to the study of calcium metabolism in rats treated with tetracycline

    International Nuclear Information System (INIS)

    The tetracycline is one of the most used antibiotics. The interferences in the rats calcium metabolism were studied. Sixteen rats, R dutch type were treated with a 1 mg/100 g of corporal weight, of tetracycline twice a day, for 23 days. In the twentieth day of the treatment, a dose of Calcium 45 was administrated to verify thhe decay curve of the radionuclide plasmatic concentration. A control group of 16 rats was studied to compare the results. A significative decrease of the calcemy and of bone reabsorption in the group treated with tetracycline were observed. (L.M.J.)

  4. 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

  5. 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.

  6. 27 CFR 45.45a - Notice for pipe tobacco.

    Science.gov (United States)

    2010-04-01

    ..., WITHOUT PAYMENT OF TAX, FOR USE OF THE UNITED STATES Packaging Requirements § 45.45a Notice for pipe... of the product contained therein. Effective Date Note: By T.D. TTB-78, at 74 FR 29420, June 22, 2009, § 45.45a was amended by removing the last sentence, effective June 22, 2009 through June 22, 2012....

  7. 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

  8. 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

  9. 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...

  10. Self-diffusion of calcium ions in soda-lime and slag glasses

    International Nuclear Information System (INIS)

    The self-diffusion coefficients of calcium ions in 16Na2O.12CaO.72SiO2(wt%) glass and 40CaO.20Al2O3.40SiO2(wt%) slag glass at temperatures near and below transition point have been measured employing radio-isotope 45Ca. The concentration gradient of radio-activity in surface layer of glass samples after diffusion annealing was determined by counting the residual activity with a GM-tube counter on the surface by progressively chemical etching away the material in steps of about 1 micron meter. It was found that the self-diffusion coefficients of calcium ions in both glasses below the transition point were of the order of 10-14 -- 10-16 cm2/s, suggesting that the mobility of calcium ions was extremely small in the solid glasses. The activation energy for diffusion of calcium ions in solid glasses was about 60 kcal/mol, which seemed to be reasonable in comparison with the electrostatic binding energy between cation and oxygen ion. The self-diffusion coefficients of calcium ions in the slag glass agrees closely with those of oxygen ions below the transition point, while the self-diffusion coefficients of calcium ions in the soda-lime glass are greater by one order of magnitude than those of oxygen ions in the same glass. The difference of diffusion behavior of calcium ions in the slag and the soda-lime glasses may be attributed to action of alkali ions on the mobility of calcium ions. (auth.)

  11. 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

  12. 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

  13. Kinetic identification of an intracellular calcium compartment sensitive to phosphate and dinitrophenol in intact isolated rabbit aorta

    International Nuclear Information System (INIS)

    Previous work from this laboratory revealed the presence of at least three distinct intracellular calcium compartments in intact segments of rabbit aorta. In this study one of these intracellular compartments is shown to be sensitive to dinitrophenol and to increased extracellular phosphate. Intact aortic segments were loaded with 45Ca in bicarbonate-buffered physiologic salt solution for 1 hour, and then transferred to a flow-through chamber perfused with physiologic salt solution. Effluent from the chamber was collected for 8 hours, and 45Ca efflux curves were analyzed using compartmental analysis. When aortic segments were loaded and washed out in dinitrophenol, the slowest component of the efflux curve was less prominent; in high phosphate it was more prominent. The rate constant changes required to account for these data were primarily in the exchange between the cytosolic and slowest intracellular calcium compartment, suggesting that the slowest calcium compartment resolved during the 8-hour washout was mitochondrial. This compartment contained 5.4 +/- 3.2 nmol calcium/g wet wt. tissue. The calcium flux across its membranes was 0.32 +/- 0.04 nmol min-1g-1. Because this flux is much smaller than the plasma-membrane calcium flux, we suggest that, in normal physiological circumstances, plasma-membrane extrusion is more important for the removal of Ca from the smooth muscle cytosol than is uptake into this slow intracellular compartment

  14. 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...

  15. 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.

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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...

  3. 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

  4. 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....

  5. 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.

  6. 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

  7. 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...

  8. 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...

  9. 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...

  10. Effects on anionic salts in a pre-partum dairy ration on calcium metabolism

    Directory of Open Access Journals (Sweden)

    C.J. Van Dijk

    2001-07-01

    Full Text Available The effects of anionic salts in the transition diet on serum and urine calcium at calving and on peripartal health, subsequent milk production and fertility performance were studied in a well-managed, high-producing Friesland dairy herd. Over a period of a year, approximately 21 days before the expected date of calving, 28 pre-partum heifers and 44 multiparous dry cows were randomly allocated within parity to 1 of 2 transition diets, designated control and experimental anionic diets. The anionic diet contained the same quantities of the basic transition ration fed to the control group as well as a standard anionic salt mixture containing 118 g NH4Cl, 36 g (NH42SO4 and 68 g MgSO4 (total 222 g per animal per day. This reduced the DCAD to -11.68 mEq/100 g dietary dry matter compared to +13.57 for the control diet. Blood and urine were randomly sampled from 7 to 8 animals within each category within 3 hours post-partum. Serum calcium (total and ionised and creatinine, urine calcium and creatinine and the fractional clearance of calcium were assessed. Relevant clinical, milk production, and fertility data were collected. The total serum calcium (2.07 versus 1.60 mmol/ , serum ionised calcium (1.12 vs 1.02 mmol/ , urine calcium (0.92 vs 0.10 mmol/ and the fractional clearance of calcium (1.88 vs 0.09 % were significantly higher (P <0.01 at calving for multiparous cows fed the anionic diet compared to those fed the control diet. In the primiparous cows there were no significant differences in serumcalcium levels. However, the urine calcium (1.07 vs 0.43 mmol/ and the fractional clearance of calcium was higher (1.75 vs 0.45 % in cows fed the anionic diet (P <0.05 and 0.01 respectively. These results illustrated that there were benefits, although no differences were demonstrated with respect to health, milk production or fertility. The supplementation of diets with anionic salts in the last 2-3 weeks before calving has the potential to significantly

  11. 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...

  12. 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.

  13. 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)

  14. Multiple myeloma: 45 cases

    International Nuclear Information System (INIS)

    We evaluated 45 cases of multiple myelomas retrospectively confirmed in Severance Hospital from the period of 1983-1989. In order to assess the radiologic features of the multiple myeloma and to assist in possible early diagnosis and treatment. The result were as follows: 1. IgG(41%) was the most common immunoglobulin type secreted followed by light chain(36%). IgA(19%) and IgD(2%). Two percent of the patients had non-secretory type. 89% of patients were in their stage III of the disease. 2. Among the 45 patients, 96% had abnormal plain radiographic findings with average number of 4.5 lesions. Common sites were the spine, rib, skull, pelvis, and humerus in descending orders. The findings were localized or diffuse osteolytic bone destruction(85%). osteoporosis(49%), pathologic fracture and endosteal scalloping(55%). Osteoporosis was more prominent in stage III than stage II. 3. Both plain X-ray and radioisotope study was available for comparison in 28 patients. Concordance between the two studies were 44%, lesions detected only on plain X-ray film were 51%, and lesions detected only on the radioisotope were 5%. The plain radiography was able to detect only 54% of bone lesions confirmed by bone marrow biopsy. With the above results, accurate evaluation of bone lesions in multiple myeloma may be difficult with radiologic studies only. But familiarity with these radiologic findings of the this disease entity is necessary for early suspicion of the disease, thus for early diagnosis and treatment

  15. 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 ...

  16. 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, ...

  17. Metabolism of intra muscularly injected 45Ca in a buffalo (Babalus bubalis) during late lactation

    International Nuclear Information System (INIS)

    Intramuscular injection of 45CaCl2 in to a buffalo during late lactation suggested an immediate transport of the injected 45Ca into blood followed by its secretion or excretion into milk, urine and faeces. Calcium from blood is concentrated several folds by mammary secretory cells before secretion. Over a period of 162 hr after administration of 45Ca, the cumulative activity of 45Ca (per cent of injected dose) secreted or excreted in the milk, urine and faeces was 11.75, 4.26 and 52.07 per cent, respectively. Subsequently secretion of 45Ca (per cent of injected dose) into milk decreased to 0.22 per cent at 1001 to 1200 hr after administration of 45CaCl2. (author). 10 refs., 3 figs., 1 tab

  18. The hemodynamic effect of calcium ion concentration in the infusate during predilution hemofiltration in chronic renal failure

    DEFF Research Database (Denmark)

    Karamperis, N.; Sloth, E.; Jensen, Jens Dam

    2005-01-01

    BACKGROUND: It is the prevailing view that convective dialysis techniques stabilize blood pressure. Calcium concentration in the substitution fluid may be important in this respect. The aim of this study is to investigate the influence of calcium ion concentration in the substitution fluid on......Eq/L (1.25 mmol/L; low-calcium session [L-HF]) or 3.5 mEq/L (1.75 mmol/L; high-calcium session [H-HF]) during 4.5 hours of predilution HF with a volume of 1.24 +/- 0.09 L/kg dry body weight and a temperature of 37 degrees C. Ultrafiltration was kept constant in each patient. Blood pressure (mean, systolic...

  19. 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

  20. Calcium and available phosphorus levels for laying hens in second production cycle

    Directory of Open Access Journals (Sweden)

    K Pelicia

    2009-03-01

    Full Text Available This experiment studied the effect of four calcium (3.0, 3.5, 4.0, and 4.5% and four available phosphorus levels (0.25, 0.30, 0.35, and 0.40% in the diet of semi-heavy commercial layers after molting. Hisex Brown® layers between 90 and 108 weeks of age were distributed in a completely randomized experimental design with a 4x4 factorial arrangement with 16 treatments of five replicates of eight birds each. mortality, egg production, feed intake, egg mass, average egg weight, calcium and phosphorus intake, feed conversion ratio (per dozen eggs and per kg eggs, eggshell percentage and thickness, eggshell strength, eggshell weight per surface area (ESWSA, yolk percentage and color, albumen percentage, albumen and yolk heights, and blood and excreta calcium and phosphorus concentrations. There was no interaction (P>0.05 between dietary Ca and avP for any of the studied parameters. There were linear increases in Ca intake (P0.05 by dietary Ca and avP levels. The diet containing 4.5% calcium improved feed conversion ratio per dozen eggs and eggshell quality. The lowest avP level fed (0.25% is sufficient to maintain the performance and the egg quality of semi-heavy commercial layers after molting.

  1. THE EFFECT OF PHOTOTHERAPY ON SERUM IONIZED CALCIUM LEVELS IN NEONATES WITH UNCONJUGATED HYPER BILIRUBINEMIA

    Directory of Open Access Journals (Sweden)

    Durga

    2015-04-01

    Full Text Available AIM : T o study the occurance of hypocalcemia in neonates with hyperbilirubinemia after 48 hours of continuous phototherapy and to compare the results between term and preterm neonates. METHODS : T his study was performed on 100 neonates with unconjugated hyper bilirubinemia , 55 term and 45 preterm , who were given photo phototherapy in neonatal intensive care unit . serum ionized calcium levels were checked and after 48 hours of phototherapy . The prevalence of hypo calcemia after 48 hrs. of phototherapy was observed and compared between full term and preterm neonates. Neonates who had hyperbilirubinemia , asphyxia , respiratory distress , haemolytic anaemia sepsis were excluded from the study . RESULTS: 46/100 NEONATES, THAT IS 46 % developed hypocalcemia. 22/55 full term neonates , that is 40% and 24/45 preterm neonates that is 53% developed hypocalcemia after 48 hrs. of phototherapy. CONCLUSION: significant decline in serum calcium level is observed in neonates receiving phototherapy for hyperbilirubinemia

  2. Leukocyte common antigen (CD45) is required for immunoglobulin E- mediated degranulation of mast cells

    OpenAIRE

    1994-01-01

    We demonstrate using primary mast cell cultures derived from wild-type and CD45-deficient mice that mast cell triggering through the high- affinity immunoglobulin E (IgE) receptor requires the cell surface tyrosine phosphatase CD45. Unlike wild-type cells, cross-linking of surface-bound IgE in mast cells deficient in CD45 does not induce degranulation. Degranulation in these mutant cells does occur after treatment with the calcium ionophore A23187 indicating that the degranulation machinery i...

  3. 45 CFR 74.45 - Cost and price analysis.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Cost and price analysis. 74.45 Section 74.45... analysis. Some form of cost or price analysis shall be made and documented in the procurement files in connection with every procurement action. Price analysis may be accomplished in various ways, including...

  4. 45 CFR 96.45 - Preventive health and health services.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Preventive health and health services. 96.45... Direct Funding of Indian Tribes and Tribal Organizations § 96.45 Preventive health and health services... preventive health and health services block grant. (b) For the purposes of determining eligible...

  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. 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.

  14. 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...

  15. 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...

  16. 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.

  17. 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

  18. 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.

  19. 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...

  20. Incidence and Progression of Aortic Valve Calcium in the Multi-Ethnic Study of Atherosclerosis (MESA)

    OpenAIRE

    Owens, David S.; Katz, Ronit; Takasu, Junichiro; Kronmal, Richard; Budoff, Matthew J.; O’Brien, Kevin D.

    2010-01-01

    Aortic valve calcium (AVC) is common among older adults and shares epidemiologic and histopathologic similarities to atherosclerosis. However, prospective studies have failed to identify meaningful risk-associations with incident (“new”) AVC or its progression. In this study, AVC was quantified from serial computed tomography (CT) images in 5,880 participants (aged 45–84 years) of the Multi-Ethnic Study of Atherosclerosis, using Agatston methodology. Multivariate backwards selection modeling ...

  1. Pharmacologic study of calcium influx pathways in rabbit aortic smooth muscle

    International Nuclear Information System (INIS)

    Functional characteristics and pharmacologic domains of receptor-operated and potential-sensitive calcium (Ca2+) channels (ROCs and PSCs, respectively) were derived via measurements of 45Ca2+ influx (M/sup Ca/) during activation by the neurotransmitters norepinephrine (NE), histamine (HS), and serotonin (5-HT) and by elevated extracellular potassium (K+) in the individual or combined presence of organic Ca2+ channel antagonists (CAts), calmodulin antagonists (Calm-ants), lanthanum (La3+), and agents that increase intracellular levels of cyclic AMP

  2. Effects of ethanol on calcium transport across the liver cell plasma membrane

    International Nuclear Information System (INIS)

    The effect of ethanol on calcium transport by the liver cell was studied by using a rat liver slice preparation. Ethanol was shown to decrease by about 30% the rate constant for 45Ca efflux from the intracellular compartment. This inhibitory effect of ethanol was not observed in the absence of Ca2+ or Na+ from the incubation medium. Ethanol was also shown to greatly increase non-insulin calcium uptake by liver slices. This effect of ethanol appeared to be dose dependent and was not observed in the absence of Na+ from the incubation medium. The ability of ethanol to increase calcium uptake by the hepatocyte was completely blocked by 1 mM Amiloride. Amiloride, however, did not affect the increased entry of either Na+ or Ca2+ produced by 10 mM Ouabain, a specific inhibitor of the sodium pump. Carbon tetrachloride (CCl4), a well known hepatotoxin, also increased calcium uptake by the hepatocyte. Amiloride, however, was not able to block the CCl4-induced calcium uptake. These results suggest that ethanol activates a Na+ entry pathway, probably represented by a Na+/H+ exchanger, which in turn stimulates an entry of Ca2+ through a Na+/Ca2+ exchange mechanism located in the plasma membrane of the hepatocyte

  3. Effects of adrenalectomy on the control and adrenergic regulation of cytosolic free calcium in hepatocytes

    Energy Technology Data Exchange (ETDEWEB)

    Freudenrich, C.C.

    1987-01-01

    The purpose of this study was to investigate the effects of adrenalectomy on the control and ..cap alpha..-adrenergic regulation of the concentration of cytosolic free calcium (Ca/sub i/) in hepatocytes. In hepatocytes isolated from adrenalectomized (adx) and sham-operated male rats 7-1 days after surgery, Ca/sub i/ at rest and in response to epinephrine (EPI) was measured with the calcium-sensitive photoprotein aequorin, /sup 45/Ca efflux was measured, and Ca/sup 2 +/ release from intracellular stores in response to inositol triphosphate (IP/sub 3/) was measured in saponin-permeabilized cells. Liver calmodulin content was also assayed by radioimmunoassay. It was found in adx rats that the resting Ca/sub i/ was elevated, the rise in Ca/sub i/ during EPI stimulation was reduced at physiological EPI concentrations, and the rise in calcium efflux evoked by EPI was reduced. Furthermore, the slope of the relationship between Ca/sub i/ and calcium efflux was reduced 60% in adx. Adx did not alter the characteristics of Ca/sup 2 +/ release from intracellular calcium pools in response to IP/sub 3/ in permeabilized cells. Finally, the liver calmodulin contents were not significantly different between the 2 groups.

  4. Calcium flouride (CaF2) from oyster shell as a raw material for thermoluminescence dosimeter

    International Nuclear Information System (INIS)

    This study aims to develop a thermoluminescence dosimeter raw material made of calcium fluoride from locally available seashells that is suitable for personal radiation monitoring. Oyster shells were collected and grounded as powder samples and analyzed for calcium fluoride (CaF2) content using XRF and XRD testing. Samples include pure CaF2, pure oyster shell, and oyster shells treated with acid. Based from the XRF results, natural oyster shell (w/ and w/o HNO3) had high percentage of calcium about 49.64% and 47.45%, next to the pure calcium fluoride of 51.08%. X-ray diffractrogram shows that oyster sample had the nearest desired structure of CaF2 compared with two seashells relative to the pure CaF2 as standard materials. Results show that all of the natural oyster samples displayed TL emission glow curves at the temperature range 200-300oC. It was also found that pure oyster sample has better TL response as compared to the treated ones. The researchers concluded that the calcium fluoride from oyster shells (without acid and heated) is a potentially good low-cost TLD raw material and may be used as an alternative for the much more expensive LiF dosimeters. (Authors)

  5. Vitamin D, calcium and phosphorus status of pregnant women and their newborns in west iran

    International Nuclear Information System (INIS)

    To determine the prevalence of Hypovitaminosis D in pregnant women and in cord blood of their newborns. Serum calcium, phosphorus and 25(OH) Vit D, were measured in 193 pregnant subjects between 16-45 years of age in third trimester admitted in Be'sat hospital. Same were measured in the cord blood of 193 newborns belonging to them. Mean maternal serum 25(OH) Vit D was 16.5+-14.2 ng/mL, and cord blood was 12+-0.2 ng/mL. Fifty-seven percent of pregnant women had 25(OH) Vit D values below the cutoff level. Seventy six percent of newborns had 25(OH) Vit D values below the cutoff level. Maternal serum 25(OH) Vit D correlated positively with cord 25(OH) Vit D (r=0.77, P<0.05). Mean maternal serum calcium was 8.89+-0.73 mg/ml and mean newborn serum calcium was 9.46+-0.93. Mean maternal serum calcium correlated with mean newborn serum calcium (r= 0.38, P<0.05). Twenty six percent of women and 37.8% of newborns had hypocalcemia. There was a high prevalence of significant hypovitaminosis D among pregnant women and their newborns. Our study emphasize the need of majority of pregnant women and their newborns to supplemental vitamin D and has significant public health implications. (author)

  6. Effects of adrenalectomy on the alpha-adrenergic regulation of cytosolic free calcium in hepatocytes

    Energy Technology Data Exchange (ETDEWEB)

    Freudenrich, C.C.; Borle, A.B.

    1988-06-25

    We have previously published that bilateral adrenalectomy in the rat reduces the Ca2+-mediated alpha-adrenergic activation of hepatic glycogenolysis, while it increases the cellular calcium content of hepatocytes. In the experiments presented here, the concentration of cytosolic free calcium (Ca2+i) at rest and in response to epinephrine was measured in aequorin-loaded hepatocytes isolated from sham and adrenalectomized male rats. We found that in adrenalectomized rats the resting Ca2+i was elevated, the rise in Ca2+i evoked by epinephrine was reduced, and the rise in /sup 45/Ca efflux that follows such stimulation was depressed. Furthermore, the slope of the relationship between Ca2+i and calcium efflux was decreased 60% in adrenalectomized. Adrenalectomy did not change Ca2+ release from intracellular calcium pools in response to IP3 in saponin-permeabilized hepatocytes. The EC50 for inositol 1,4,5-triphosphate and the maximal Ca2+ released were similar in both sham and adrenalectomized animals. Finally, the liver calmodulin content determined by radioimmunoassay was not significantly different between sham and adrenalectomized rats. These results suggest that 1) adrenalectomy reduces calcium efflux from the hepatocyte, probably by an effect on the plasma membrane (Ca2+-Mg2+)-ATPase-dependent Ca2+ pump and thus alters cellular calcium homeostasis; 2) adrenalectomy decreases the rise in Ca2+i in response to epinephrine; 3) this decreased rise in Ca2+i is not due to defects in the intracellular Ca2+ storage and mobilization processes; and 4) the effects of adrenalectomy on cellular calcium metabolism and on alpha-adrenergic activation of glycogenolysis are not caused by a reduction in soluble calmodulin.

  7. 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.

  8. 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.

  9. Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Ganesan Lavanya

    2015-01-01

    Full Text Available This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 2.50. The molarity of sodium hydroxide was fixed as 12. The test specimens were 150×150×150 mm cubes, 100×200 mm cylinders, and 100×50 mm discs cured at ambient temperature. Surface deterioration, density, and strength over a period of 14, 28, and 45 days were observed. The results of geopolymer and ordinary Portland cement concrete were compared and discussed. After 45 days of exposure to the magnesium sulfate solution, the reduction in strength was up to 12% for geopolymer concrete and up to 25% for ordinary Portland cement concrete. After the same period of exposure to the sulphuric acid solution, the compressive strength decrease was up to 20% for geopolymer concrete and up to 28% for ordinary Portland cement concrete.

  10. 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.

  11. 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.)

  12. 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

  13. Polar fluxes of calcium ions and growth of plant tissues

    International Nuclear Information System (INIS)

    The authors studied the action exerted by auxin transport inhibitors (2,3,5-triiodobenzoic acid, 10-4 M; 1-N-naphthylphthalamic acid, 10-4 M), inhibitors of membrane-bound ATPases (sodium orthovanadate, 10-4 M; diethylstilbestrol, 10-5 M), and a blocker of Ca-channels (verapamil, 1.3 x 10-4 M) on growth processes (lengthwise growth, the gravitropic response) and translocation of 45Ca in segments of corn (Zea mays L.) coleoptiles and pea (Pisum sativum L.) internodes. Calcium in vertically oriented and gravistimulated segments was polarly translocated in a direction opposite the vector of gravitational force. It is hypothesized that the polar fluxes of Ca2+ ions which arise in tissues with a change in position of the plant organism in space are capable of correcting the direction of active basipetal transport of IAA and thereby able to induce polarization of growth processes. In studying transport of Ca2+ ions on plasmalemma vesicles with the aid of chlorotetracycline, it was found that creation of a potassium diffusion potential on the membrane (as a results of valinomycin treatment) induces entry of calcium into the vesicles. Since this effect was removed by verapamil and ruthenium red, it is postulated that potential-dependent Ca-channels are present on the plasma membrane of corn coleoptile cells

  14. Use of calcium hydroxylapatite (Radiesse® for facial augmentation

    Directory of Open Access Journals (Sweden)

    Patricio F Jacovella

    2008-03-01

    Full Text Available Patricio F JacovellaHospital de Clinicas, University of Buenos Aires, ArgentinaAbstract: Radiesse® (Bioform Inc, USA is a sterile, latex-free, non-pyrogenic, semi-solid, cohesive subdermal, injectable implant, whose principal component is synthetic calcium hydroxylapatite, a biocompatible material with over 20 years of use in medicine. The semi-solid nature of the product is created by suspending calcium hydroxylapatite microspheres of 25–45 microns diameter in a gel carrier of carboxymethylcellulose. The product has FDA approval for esthetic facial augmentation in the US. Such approval includes the long-lasting correction of moderate to severe facial wrinkles and folds and the treatment of facial fat loss due to immunodeficiency virus infection. Diverse facial regions can be injected in order to ameliorate or enhance some features: glabellar lines, subdermal support of the brows, malar and buccal fat pads, tear troughs, nasolabial folds, nose, lips, perioral region, marionette lines, oral commisures and chin among others, as well as saucerized acne scars. Other medical indications include nipple projection for nipple areolar reconstruction, urinary incontinence, vesicoureteral reflux, vocal cord augmentation, and use as a radiographic tissue marker. The average lasting result is from 12 to 18 months. Radiesse can be considered an effective soft-tissue filler for overall longevity, biocompatibility, and low rate of side effects.Keywords: hydroxylapatite, facial augmentation, Radiesse

  15. 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.

  16. 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.

  17. The Incredible, Embryological Egg: Calcium and Strontium Isotopes Recapitulate Ontogeny

    Science.gov (United States)

    Gordon, G. W.; Skulan, J. L.

    2011-12-01

    that caused by osteoporosis in humans. For both mass-dependent Ca and Sr isotopes, the isotopic value of the albumen is the highest natural value yet measured. The offset between the δ88/86Sr values of the albumen and shell is 0.45%, less than half that of the δ44/42Ca offset value (1.29%), as predicted by the relative mass differences. However, the yolk is 0.35% heavier than the shell in δ44/42Ca but 0.70% lighter in δ88/86Sr. In addition, the 87Sr/86Sr value of the shell (0.70854 ±0.000012, 2σ) is statistically the same as the albumen (0.70856 ±0.000018), but slightly offset from the yolk (0.70830 ±0.000014). The apparent decoupling of Ca and Sr, and the radiogenic offset between yolk and shell, may reflect differences in the residence time of calcium and strontium in different reproductive organs, as well as the contribution of medullary bone to shell formation. In addition, it may also reflect differential discrimination against Sr versus Ca in oviduct and uterus. Further studies could extend to thinning eggshells in wild avian populations, biochemical mechanisms of bone formation, and the mechanism of strontium ranelate in the treatment of osteoporosis.

  18. β-endorphin modulation of mitogen-stimulated calcium uptake by rat thymocytes

    International Nuclear Information System (INIS)

    Lymphocytes stimulated by mitogens or antigens exhibit an enhanced calcium uptake early in the proliferation or activation response. Modulation of this calcium uptake results in alterations of proliferation and immunocompetence. β-endorphin and other opioids affect several parameters of lymphocyte competence. Limited data are available concerning the mechanism(s) of these effects. This study examines whether a possible opioid mechanism is the modification of the early calcium influx into stimulated lymphocytes. The time course of both concanavalin A (Con A) and phytohemagglutinin (PHA)-stimulated 45Ca2+ uptake into thymocytes was characterized to determine the optimal time for testing the effects of opioids. Β-Endorphin 1-31 significantly enhanced Con A-stimulated 45Ca2+ uptake into rat thymocytes. This peptide had no significant effect on PHA-simulated 45Ca2+ uptake or on basal thymocyte 45Ca2+ flux. The β/sub h/-endorphin stimulatory effect was titratable in the range of 0.1 nM to 10 μM. Naloxone did not reverse the enhancement. Met-enkephalinamide and other opioid agonists did not duplicate the stimulatory effect. Thus, the β/sub h/-endorphin 1-31 enhancement of Con A-stimulated 45Ca2+ uptake by rat thymocytes does not operate via classical opioid receptor mechanisms. β/sub h/-endorphin 1-31 appears to be acting on a subset of T cells that are responsive to Con A but not to PHA. 30 references, 4 figures, 1 table

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-10-19

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

  20. Taurine effects on 45Ca2+ transport in retinal subcellular fractions

    International Nuclear Information System (INIS)

    The effect of taurine on 45Ca2+ transport by subcellular fractions from the chick retina was examined. An inhibitory action of taurine on 45Ca2+ uptake was observed in retinal fractions incubated for 1-5 min in a Krebs-bicarbonate medium, pH 7.4. In the crude nuclear fraction, 25 mM taurine produced a decrease of 50% in 45Ca2+ uptake; in the crude synaptosomal fraction, taurine reduced 45Ca2+ accumulation by 70%; the maximum inhibitory effect of taurine on 45Ca2+ uptake (80%) was observed in a fraction containing outer segments and pigment epithelium cells. Taurine effect was specific, dose-dependent and related to osmotically sensitive particles. The results suggest a role of taurine in the regulation of calcium fluxes in the retina. (Auth.)

  1. 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.

  2. 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

  3. 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.

  4. 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...

  5. Calcium overload injury of rats' enterocyte IEC-6 by heat stress in vitro

    Directory of Open Access Journals (Sweden)

    Yan GENG

    2013-07-01

    Full Text Available Objective To investigate the effect of gradient heat stress on calcium overload of rats' enterocyte IEC-6 and calcium overload-related cell injury in vitro. Methods Thermal gradient was set in culturing IEC-6 cells in vitro. After thermal stimulation, Fluo-3Am probe with fluorescence microscope or flow cytometry was used to detect the change in intracellular Ca2+ concentration of IEC-6 cells. Phase contrast microscope was used to observe the morphological change in IEC-6. Coomassie blue dying method was employed to test the change in IEC-6 cytoskeleton. CCK-8 assay was used to assess cellular viability. Adhesion assay was applied to test the change in basilar membrane adhesiveness of IEC-6 cells. Results Compared with normal control group, cells of heat stress groups showed a thermal-dependent increase in intracellular Ca2+ concentration (P<0.01. Cells of heat stress groups were rounded in shape, the pseudopod was shorter, and cell space was enlarged. These phenomena were more obvious in 45℃ culture than in that of 43℃. Coomassie blue dying showed that the cytoskeleton of cells in heat stress groups became thickened and disordered, and stress fibers appeared. These phenomena were also more obvious in 45℃ culture than in that of 43℃. A thermal-dependant decline of cell viability in heat stress groups was observed via CCK-8 assay (P<0.01, and a thermal-dependant decline of basilar membrane adhesiveness in heat stress groups was observed via adhesion assay (P<0.01. Conclusion Heat stress may cause calcium overload of IEC-6 cells, and thus resulting in a series of calcium overload-related cell injury. Further investigation of the effect and mechanism of heat stress on calcium overload of intestinal mucosa endothelial cells may help further understand the mechanism of the pathogenesis of heat stroke.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-21

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

  7. A COMPARATIVE STUDY OF EFFICACY OF CALCIUM + VITAMI N D3 AND CALCIUM + VITAMIN D3 + VITAMIN K2 IN PREVENTION OF OSTEOPOROSIS IN POSTMENOPAUSAL OSTEOPENIC WOMEN WHO ARE ADOPTING A SEDENTARY PATTERN OF LIFE STYLE

    Directory of Open Access Journals (Sweden)

    Verma

    2013-05-01

    Full Text Available ABSTRACT: OBJECTIVE:- The aim of the study was to determine the efficacy of combination of vitamin K2+ vitamin D3+calcium in prevention of ost eoporosis in osteopenic postmenopausal women . MATERIALS AND METHODS: This study included 60 postmenopausal osteopenic w omen. They were divided in two groups one group were admi nistered 1gm calcium+ vitamin D3 1 mcg /day and other group were administered 1gm calcium+ vita min D3 1mcg+vitamin K2 45mg/day. All the patients were investigated for bone marker undercar boxilated osteocalcin, N Telopeptide and bone mineral density. RESULTS: It was observed that group I that was treat with vi tamin D3+calcium had less percentage improvement in bone mineral density and reduction of undercarboxilated osteocalcin and N telopeptide in comparison to patients who wer e treat with vitamin K2+vitaminD3+calcium observed had more percentage improvement in bone mi neral density and reduction of undercarboxilated osteocalcin and N telopeptide. CONCLUSION- According the results of this study vitamin K2 to be more effective as a protective age nt than combined calcium and vitamin D3 administration in cases of osteoporosis.

  8. 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...

  9. 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 ...

  10. 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 ...

  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. 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

  9. 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...

  10. 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 ...

  11. 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

  12. 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.

  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. Maitotoxin: Effects on calcium channels, phosphoinositide breakdown, and arachidonate release in pheochromocytoma PC12 cells

    International Nuclear Information System (INIS)

    Maitotoxin (MTX) increases formation of [3H]inositol phosphates from phosphoinositides and release of [3H]arachidonic acid from phospholipids in pheochromocytoma PC12 cells. Formation of [3H]inositol phosphates is detected within 1 min of incubation even with concentrations as low as 0.3 ng/ml (90 pm) MTX, whereas release of [3H]arachidonic acid is not detected until 20 min even with concentrations as high as 1 ng/ml (300 pm) MTX. Stimulation of arachidonic acid release can be detected at 0.03 ng/ml (9 pm) MTX, whereas 0.1 ng/ml (30 pm) MTX is the threshold for detection of phosphoinositide breakdown. Organic and inorganic calcium channel blockers, except Cd2+ and a high concentration of Mn2+, have no effect on MTX-elicited phosphoinositide breakdown, whereas inorganic blockers (e.g., Co2+, Mn2+, Cd2+), but not organic blockers (nifedipine, verapamil, diltiazem), inhibit MTX-stimulated arachidonic acid release. All calcium channel blockers, however, inhibited MTX-elicited influx of 45Ca2+ and the MTX-elicited increase in internal Ca2+ measured with fura-2 was markedly reduced by nifedipine. MTX-elicited phosphoinositide breakdown and arachidonic acid release are abolished or reduced, respectively, in the absence of extracellular calcium plus chelating agent. The calcium ionophore A23187 has little or no effect alone but, in combination with MTX, A23187 inhibits MTX-elicited phosphoinositide breakdown and enhances arachidonic acid release, the latter even in the absence of extracellular calcium. The results suggest that different sites and/or mechanisms are involved in stimulation of calcium influx, breakdown of phosphoinositides, and release of arachidonic acid by MTX

  18. 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)

  19. 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...

  20. 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...

  1. 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 ...

  2. 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...

  3. Aging Reduces L-Type Calcium Channel Current and the Vasodilatory Response of Small Mesenteric Arteries to Calcium Channel Blockers

    Science.gov (United States)

    Albarwani, Sulayma A.; Mansour, Fathi; Khan, Abdul Aleem; Al-Lawati, Intisar; Al-Kaabi, Abdulla; Al-Busaidi, Al-Manar; Al-Hadhrami, Safa; Al-Husseini, Isehaq; Al-Siyabi, Sultan; Tanira, Musbah O.

    2016-01-01

    Calcium channel blockers (CCBs) are widely used to treat cardiovascular disease (CVD) including hypertension. As aging is an independent risk factor for CVD, the use of CCBs increases with increasing age. Hence, this study was designed to evaluate the effect of aging on the sensitivity of small mesenteric arteries to L-type voltage-gated calcium channel (LTCC) blockers and also to investigate whether there was a concomitant change in calcium current density. Third order mesenteric arteries from male F344 rats, aged 2.5–3 months (young) and 22–26 months (old) were mounted on wire myograph to measure the tension during isometric contraction. Arteries were contracted with 100 mM KCl and were then relaxed in a cumulative concentration-response dependent manner with nifedipine (0.1 nM–1 μM), verapamil (0.1 nM–10 μM), or diltiazem (0.1 nM–10 μM). Relaxation-concentration response curves produced by cumulative concentrations of three different CCBs in arteries of old rats were shifted to the right with statistically significant IC50s. pIC50 ± s.e.m: (8.37 ± 0.06 vs. 8.04 ± 0.05, 7.40 ± 0.07 vs. 6.81 ± 0.04, and 6.58 ± 0.07 vs. 6.34 ± 0.06) in young vs. old. It was observed that the maximal contractions induced by phenylephrine and reversed by sodium nitroprusside were not different between young and old groups. However, Bay K 8644 (1 μM) increased resting tension by 23 ± 4.8% in young arteries and 4.7 ± 1.6% in old arteries. LTCC current density were also significantly lower in old arteries (−2.77 ± 0.45 pA/pF) compared to young arteries (−4.5 ± 0.40 pA/pF); with similar steady-state activation and inactivation curves. Parallel to this reduction, the expression of Cav1.2 protein was reduced by 57 ± 5% in arteries from old rats compared to those from young rats. In conclusion, our results suggest that aging reduces the response of small mesenteric arteries to the vasodilatory effect of the CCBs and this may be due to, at least in part, reduced

  4. Preparation of 45Ca(HDEHP)n and (CaH{sub 1}50{sub 2})2 samples for liquid scintillation counting, compared to 45caCl{sub 2} results; Preparacion de Ca (HDEHP)n y (C{sub 8}H{sub 1}50{sub 2})2 marcados con 45Ca y estudio comparativo con 4 5ca Cl2 en medidas por centelleo liquido

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, L.; Arcos, J. M. los; Grau Malonda, A.

    1994-07-01

    A procedure for preparation of liquid scintillation counting organic samples of the Di-2-ethylhexyl phosphate calcium complex and the 2-ethylhexanoate calcium salt, labelled with 45Ca, is described. The chemical quench, the counting stability and spectral evolution of both compounds is studied in six scintillators,Toluene-alcohol, Dioxane-naphtalene, Hi safe II, Ultimate-Gold and Instagel, and compared to results obtained from a commercial solution of 4 5CaCl2. (Author) 7 refs.

  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. 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...

  7. 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.

  8. 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

  9. Carbon monoxide effects on calcium levels in vascular smooth muscle

    International Nuclear Information System (INIS)

    Previously the authors showed that carbon monoxide (CO) relaxes vascular smooth muscle in the working heart and thoracic aorta preparation perfused with hemoglobin-free, Krebs-Henseleit (KH) solution. The CO-induced relaxation was not caused by hypoxia, nor was it mediated by adrenergic influences, adenosine, or prostaglandins. In these studies the effect of CO on calcium (Ca++) concentrations in vascular smooth muscle was determined using 45Ca as a tracer. Isolated rat thoracic aorta segments were incubated with 45Ca and gassed with O2, N2, or CO for 60 min. Verapamil was used to verify the effectiveness of the test system. Ca++ concentrations were 488 /+ -/ 35 and 515 /+ -/ 26 mM/g tissue (X /+ -/ SE) in aortic rings gassed with O2 and N2, respectively. CO reduced Ca++ concentrations significantly (P++ concentrations by 40% to 314 /+ -/ 23 mM/g tissue. These results suggest that CO relaxes vascular smooth muscle and dilates blood vessels by decreasing Ca++ concentrations in vascular smooth muscle

  10. Characterization of voltage calcium channels in a clonal pituitary cell line

    International Nuclear Information System (INIS)

    The authors have pharmacologically characterized voltage sensitive calcium channels (VSCCs) in GH3 cells, an anterior pituitary clonal cell line known to secrete prolactin and growth hormone. Raising the medium K+ concentration from 5 to 50 mM caused an immediate increase in net 45Ca2+ uptake which remained apparent over a 15 minute time course. 45Ca2+ uptake was maximally stimulated nearly 10-fold over basal levels. This K+-induced stimulation of Ca2+ uptake was not prevented by 10-5M tetrodotoxin or by replacing sodium with choline in the assay medium. Ca2+ uptake was, however, inhibited by several VSCC antagonists: nitrendipine, D-600, diltiazem and Ca2+. Further, the novel dihydropyridine VSCC agonists, BAY K8644 and CGP 28392, enhanced 50-mM K+-stimulated 45Ca2+ uptake and these effects were blocked by nitrendipine. 40 references, 3 figures

  11. An interventional study (calcium supplementation & health education on premenstrual syndrome - effect on premenstrual and menstrual symptoms

    Directory of Open Access Journals (Sweden)

    Shailesh Sutariya, Nitiben Talsania, Chintul Shah, Mitesh Patel

    2011-01-01

    Full Text Available The study was conducted to study the effect of calcium supplementation on Premenstrual and Menstrual Symptoms. It was a one year follow-up prospective, randomized controlled interventional study. After the initial 2-cycle screening phase, a total of 215 healthy premenopausal women were enrolled in the study group calcium supplementation(500 BD of the trial and 140 subjects either the relatives or neighbors of the study population were enrolled as control group health, nutrition, hygiene education of the trial. By the second and third treatment months, all symptoms except for fatigue and insomnia showed a significant response to calcium. For the symptom of low backache, the mean screening score was significantly higher than the control group score (0.82±0.74 vs 0.69±0.66,p=0.033 and became significantly lower than the control group score by the end of third treatment cycle. (0.30±0.45 vs 0.49±0.59,p<0.01. Nearly half (55% of the women in the study group reported ?50% improvement and one-third (30% of the women in study group reported ?75% improvement. Significantly lower symptoms score was detected in the urban sites during the first treatment phase with calcium and during the final treatment phase

  12. CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

    Directory of Open Access Journals (Sweden)

    Kaziliunas A.

    2013-12-01

    Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

  13. Effects of inositol trisphosphate on calcium mobilization in high-voltage and saponin-permeabilized platelets

    International Nuclear Information System (INIS)

    Interest in phosphatidylinositol metabolism has been greatly stimulated by the findings that diglyceride and inositol phosphates may serve as second messengers in modulating cellular function. Formation of 1,4,5-inositol trisphosphate (IP3), in particular, has been linked to mobilization of intracellular calcium in a number of cell types. The authors have examined the ability of IP3 to mobilize calcium in human platelets permeabilized by either saponin or high-voltage discharge. Saponin at 15 μg/ml effectively permeabilized platelets to exogenous inositol 1,4,5-trisphosphate which released bound [45Ca] within 1 min and with a Ka of 7.4 +/- 4.1 μM. A small (25%) azide-sensitive pool was also responsive to inositol trisphosphate. The calcium pools were completely discharged by A-23187 and the ATP-dependent uptake was prevented by dinitrophenol. In contrast to the result with saponin, platelets accessed by high-voltage discharge were insensitive to challenge by inositol 1,4,5-trisphosphate. The data suggest that while inositol 1,4,5-trisphosphate can rapidly mobilize platelet calcium, the ability to demonstrate this depends on the method of permeabilization

  14. INIS at 45 years

    International Nuclear Information System (INIS)

    Do you remember punched paper tape? That’s how many INIS Member States sent their input to the database in the early years of the system. And you had to be careful with that tape; a torn paper tape was a nuisance. Of course the rolls of paper came by post, how else? And if it took two weeks to get a postal package with paper tape in it from somewhere in Asia to Vienna, so be it! Of course the more sophisticated INIS imputing centers used magnetic tapes. Yes, magnetic tapes were also shipped by post from the ends of the earth to Vienna and that also sometimes took weeks. I recall the total thesaurus revision that we undertook in 1971. INIS had taken over the nuclear terminology contained in the thesaurus of the ENDS system (European Nuclear Documentation System of the European Community) but soon decided on a total revision, total in the sense that we decided to revise both the terminological content of the thesaurus AND the structure (interrelationships) that was given to the terminology. Who were the “we” who carried out the revision? Staff at the national INIS centres of Czechoslovakia (as it was at the time), France, the U.S.A. and staff at the University of California in Berkley, California, plus of course the INIS staff in Vienna. Magnetic tapes were naturally the support used for the exchange of data. Can you imagine the crisscrossing of tapes around the globe during that one year of work? Almost incredible by today’s standards, where the tip of a key will send immeasurably vaster quantities of data anywhere on earth within a fraction of a second! But apart from its technological aspects and the continuous developments that these were subjected to and from which the system profited, it was the human aspect of the system, that is, the people that made INIS work, that was so interesting, challenging and finally rewarding for all those involved. And here we must immediately stress that what made the system such a success over these past 45 years, was

  15. Aluminium effects on calcium uptake in chicken isolated duodenal cells

    International Nuclear Information System (INIS)

    Full text: The objective of this work was to study in vitro actions of aluminium (Al) on kinetics of radio calcium uptake (45CaUPT) in chicken isolated duodenal cells. Epithelial cells, obtained according to method described by Liang et al., were incubated in aero-biosis, during 30 min. with 0 and 100 μM Al lactate, at [Ca2+] varying from 0.01 to 5 μM (pH 7.4). Apparent constants Vmax and Km were calculated from 45CaUPT vs. [Ca2+] plots by a non-linear fitting method using the Marquardt-Levenburg algorithm. Curves were compared by analysis of covariance. In other series of experiments, enterocytes were treated with Al in presence of: 1) diltiazem (D) or nifedipine (N) (blockers of L-type voltage-dependent Ca channels, VOCC): 1, 10 and 100 μM; 2) A23187 (Ca ionophore): 1 μM; 3) Bay K8644 (Ca channel activator, acting on dihydroxypyridine site): 1 μM; 4) capsaicin (activator of Epithelial Calcium Channel, ECaC): 2 and 20 μM; 5) U73122 (activator of store-operated Ca channels): 1 nM. Controls were incubated with respective vehicles (C). Results were expressed as % of respective Al-free control. Al significantly reduced both Vmax (15.3 ± 1.9 vs. 22.1 ± 3.4 nmol Ca/mg prot.) and Km (1.4 ± 0.2 vs. 2.1 ± 0.4 mM) as compared to Al-free control (P< 0.05). D from 1 μM (101 ± 2 %) and N from 10 μM (100 ± 3%), completely annulled Al inhibition as compared to C (56 ± 3%). Bay K8644 (82 ± 4%), U73122 (84 ± 3%) and capsaicin (2 μM= 97 ± 2%, 20 μM= 89 ± 3%) reduced Al inhibition. A23187 increased Al inhibition (45 ± 3%, n = 4, P< 0.05, ANOVA). In summary, Al could reduce Ca entry in chicken enterocytes acting directly on VOCC, preferably in the open state of channels. (author)

  16. 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

  17. 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...

  18. 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.

  19. 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)

  20. 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

  1. 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

  2. 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...

  3. 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...

  4. Whole body retention of Tc-99m Methylene Diphosphonate (MDP) in monitoring skeletal calcium status in post-menopausal women

    International Nuclear Information System (INIS)

    The detection and estimation of skeletal calcium loss has become an important consideration in the management of post-menopausal women. The need to supplement large amounts of calcium of 1000-1500 mg per day is recommended to forestall the risk of skeletal fractures. The added supplementation of estrogens and progesterone for several years is also recommended to prevent bone calcium loss. The need to record the calcium status in post-menopausal women is becoming necessary in the present scenario. A total of 159 women in the peri-menopausal, menopausal and post-menopausal groups were selected. None of them had other systemic diseases. They were healthy and not on any medication. They were randomly grouped into 3 groups. One was considered as control and no medication was advised. The second group was advised 1000-1500 mg of calcium carbonate daily. The third group was given the same dose of calcium, but also received additionally another 2 mg of estradiol daily. Whole Body Retention (WBR) studies of Tc-99m MDP were carried out before starting treatment and at 6 monthly intervals for a period of 5 years. Serum calcium and alkaline phosphatase were estimated on fasting samples at the start of the study and at every 6 monthly intervals. WBR studies were done using a shadow shield whole body counter attached with a 5 inch diameter sodium iodide crystal detector and a 5 mm wide slit collimator. The WBR of Tc-99m MDP at 24 hours was found to be 27.55 ± 6.76% in women in the peri-menopausal age range of 25-45 years. It was also observed that at the time of menopause 13.3% of the women had WBR values above 2 SD of the normal values. This suggests that calcium loss from the skeleton is present only in a small number of women at menopause. However in women who were not supplemented with calcium or subjected to hormonal and calcium treatment, the number of women who showed loss of bone calcium increased within a period of 1-2 years after menopause. This simple method of WBR

  5. Nanoscale observations of the effect of citrate on calcium oxalate precipitation on calcite surfaces.

    Science.gov (United States)

    Burgos-Cara, Alejandro; Ruiz-Agudo, Encarnacion; Putnis, Christine V.

    2016-04-01

    . Inhibition of calcium oxalate monohydrate growth by citrate and the effect of the background electrolyte. J Cryst Growth 2007;306:135-45.

  6. 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.

  7. 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....

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Comparison of intrinsic and extrinsic tracer methods for estimating calcium bioavailability to rats from dairy foods

    International Nuclear Information System (INIS)

    Dairy products doubly labeled with 45Ca and 47Ca were used to evaluate an extrinsic labeling procedure for calcium bioavailability determination. Nonfat milk, yogurt, and fresh cheese curd were prepared from caprine milk that was intrinsically labeled with 45Ca. The products were then labeled extrinsically with 47Ca and administered to rats by gavage. The 47Ca to 45Ca ratio in bone and teeth averaged about 1.00 with either milk, yogurt, or CaCl2, but the ratio was about 1.04 when dosed with cheese curd. Ca absorption, determined by whole-body counting of 47Ca, was lower (P less than 0.05) in cheese curd (59%) than in either milk (69%), yogurt (72%), or CaCl2 (72%). Expressed as percent of dose, the absorption of 47Ca was highly correlated with bone 47Ca (r = 0.973) and with bone 45Ca (r = 0.946). Correlation between tibia 47Ca and tibia 45Ca was r = 0.923. For the dairy products tested, our results indicated that extrinsic 47Ca was absorbed similarly to intrinsic 45Ca. Moreover, the percent of radioactive dose retained in bone appears to be a valid indicator of relative bioavailability of food Ca

  13. 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

  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. Biochemical and functional interactions of a selective kappa opioid agonist with calcium

    Energy Technology Data Exchange (ETDEWEB)

    VonVoigtlander, P.F.; Ochoa, M.C.; Lewis, R.A.

    1987-01-01

    The discovery of the selective kappa opioid receptor agonist, U-50488H, has provided a tool for the study of the mechanisms and function of the kappa receptor-effector. We have investigated the interactions of this compound with calcium in several biochemical and functional studies to assess the involvement of calcium mechanisms in the kappa receptor-linked effector. In rat brain synaptosomes, U-50488H attenuated the uptake of /sup 45/Ca++ induced by K+ (40 mM) depolarization. This effect was concentration-related (U-50488H 10(-5) to 10(-7) M), was apparent in short (8-second) but not longer (1-minute) term incubations, and did not occur in the presence of a non-polarizing concentration (5.6 mM) of K+. Naloxone (10(-7) M) did not block this effect of U-50488H (10(-6) M), and higher concentrations (10(-5) M) alone blocked calcium uptake. We have found that the binding of the depolarizing amino acid analog, kainic acid, is enhanced by CaCl2. U-50488H (10(-4) to 10(-6) M) blocks this enhancement of /sup 3/H-kainic acid binding in vitro and also blocks the in vivo effects of kainic acid. In mice, intravenous injection of kainic acid causes scratching, convulsions, and death, depending on the dose administered. U-50488H blocks all of these effects (ED50 = 4.5 mg/kg for antagonism of convulsions induced by 27.5 mg/kg kainic acid). The convulsions induced by intracerebroventricularly administered kainic acid are also blocked by U-50488H as are those induced by similarly administered Bay K 8644, a calcium channel activator. All of these anticonvulsant effects of U-50488H were antagonized by naltrexone. Together these data indicate that the kappa agonist U-50488H has functionally relevant interactions with depolarization-related Ca++ mechanisms in the central nervous system.

  18. Biochemical and functional interactions of a selective kappa opioid agonist with calcium

    International Nuclear Information System (INIS)

    The discovery of the selective kappa opioid receptor agonist, U-50488H, has provided a tool for the study of the mechanisms and function of the kappa receptor-effector. We have investigated the interactions of this compound with calcium in several biochemical and functional studies to assess the involvement of calcium mechanisms in the kappa receptor-linked effector. In rat brain synaptosomes, U-50488H attenuated the uptake of 45Ca++ induced by K+ (40 mM) depolarization. This effect was concentration-related (U-50488H 10(-5) to 10(-7) M), was apparent in short (8-second) but not longer (1-minute) term incubations, and did not occur in the presence of a non-polarizing concentration (5.6 mM) of K+. Naloxone (10(-7) M) did not block this effect of U-50488H (10(-6) M), and higher concentrations (10(-5) M) alone blocked calcium uptake. We have found that the binding of the depolarizing amino acid analog, kainic acid, is enhanced by CaCl2. U-50488H (10(-4) to 10(-6) M) blocks this enhancement of 3H-kainic acid binding in vitro and also blocks the in vivo effects of kainic acid. In mice, intravenous injection of kainic acid causes scratching, convulsions, and death, depending on the dose administered. U-50488H blocks all of these effects (ED50 = 4.5 mg/kg for antagonism of convulsions induced by 27.5 mg/kg kainic acid). The convulsions induced by intracerebroventricularly administered kainic acid are also blocked by U-50488H as are those induced by similarly administered Bay K 8644, a calcium channel activator. All of these anticonvulsant effects of U-50488H were antagonized by naltrexone. Together these data indicate that the kappa agonist U-50488H has functionally relevant interactions with depolarization-related Ca++ mechanisms in the central nervous system

  19. Purification and partial characterization of a novel calcium-binding protein from Bacillus cereus T spores and inhibition of germination by calmodulin antagonists

    International Nuclear Information System (INIS)

    A novel calcium-binding protein has been purified from the dormant spores of Bacillus cereus T. B. cereus T spores were extensively washed, broken, and heated at 90 degree C for 2 min. Using calcium-dependent hydrophobic interaction chromatography plus DEAE-cellulose and hydroxylapatite columns, a single protein was obtained which possessed calcium-binding capacity and some characteristics of calmodulin. This heat-stable protein was retained by hydrophobic matrices or a calmodulin antagonist in a calcium-dependent manner. The crude spore extract displaced bovine brain calmodulin from its antibody in a radioimmunoassay and the immunoreactive specific activity of the partially purified fraction which eluted from phenyl-Sepharose was ca. 200-fold greater than the crude spore extract. Purity of this protein was verified by sodium dodecyl sulfate-polyarcylamide gel electrophoresis and reversed-phase HPLC. Calcium-binding ability was verified with a competitive calcium binding assay using Chelex-100 resin and 45Ca autoradiography. SDS-PAGE and amino acid composition indicated the molecular weight of the protein was 24-kDa. The effects of two calmodulin antagonists, trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W-7) on L-alanine-induced germination of Bacillus cereus T spores were examined by measuring commitment to germination, loss of heat resistance, release of calcium, decrease in optical density at 660 nm and phase-contrast microscopy

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Comparison of serum calcium, copper and iron levels in serum samples from gallstone patients and control subjects

    International Nuclear Information System (INIS)

    Objective: Present study was designed to investigate the levels of calcium, copper and iron in the serum samples of gallstone patients and control subjects with no personal or family history of gallstones. Methodology: Sera of 109 gallstone patients and 100 control subjects were obtained during January 2010 to November 2010 from Memon Charitable Hospital, Hyderabad. The serum calcium, copper and iron concentrations were determined by Hitachi double beam atomic absorption spectrophotometer 180 - 50. Results: Comparison of serum calcium, copper, and iron levels between gallstone patients and control subjects showed that all these variables were significantly (p0.01) was found when mean serum concentrations for these variables were compared between male and female gallstone patients, between female gallstone patients of up to 45 and over 45 years age and between female gallstone patients having up to 3 and more than 3 children. Conclusions: The higher levels of calcium, copper and iron in blood samples of gallstone patients compared to controls suggest that these metals do play a contributory role in the pathogenesis of human gallstones. (author)

  6. 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

  7. 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.)

  8. 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)

  9. 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...

  10. 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

  11. 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 ...

  12. SNX-325, a novel calcium antagonist from the spider Segestria florentina.

    Science.gov (United States)

    Newcomb, R; Palma, A; Fox, J; Gaur, S; Lau, K; Chung, D; Cong, R; Bell, J R; Horne, B; Nadasdi, L

    1995-07-01

    A novel selective calcium channel antagonist peptide, SNX-325, has been isolated from the venom of the spider Segestria florentina. The peptide was isolated using as bioassays the displacement of radioiodinated omega-conopeptide SNX-230 (MVIIC) from rat brain synaptosomal membranes, as well as the inhibition of the barium current through cloned expressed calcium channels in oocytes. The primary sequence of SNX-325 is GSCIESGKSCTHSRSMKNGLCCPKSRCNCRQIQHRHDYLGKRKYSCRCS, which is a novel amino acid sequence. Solid-phase synthesis resulted in a peptide that is chromatographically identical with the native peptide and which has the same configuration of cysteine residues as the spider venom peptide omega-Aga-IVa [Mintz, I. M., et al., (1992) Nature 355, 827-829]. At micromolar concentrations, SNX-325 is an inhibitor of most calcium, but not sodium or potassium, currents. At nanomolar concentrations, SNX-325 is a selective blocker of the cloned expressed class B (N-type), but not class C (cardiac L), A, or E, calcium channels. SNX-325 is approximately equipotent with the N-channel selective omega-conopeptides (GVIA and MVIIA as well as closely related synthetic derivatives) in blocking the potassium induced release of tritiated norepinephrine from hippocampal slices (IC50s, 0.1-0.5 nM) and in blocking the barium current through cloned expressed N-channels in oocytes (IC50s 3-30 nM). By contrast, SNX-325 is 4-5 orders of magnitude less potent than is SNX-111 (synthetic MVIIA) at displacing radioiodinated SNX-111 from rat brain synaptosomal membranes. SNX-325 will be a useful comparative tool in further defining the function and pharmacology of the N- and possibly other types of high-voltage activated calcium channels. PMID:7541240

  13. Radioligand assay of cardiac calcium release channel and its application in SHR

    International Nuclear Information System (INIS)

    Purpose: To establish the best condition in assaying the calcium release channel (ryanodine receptor) in cardiac sarcoplasmic reticulum (CSR), and analyse the CSR ryanodine receptor in spantanous hypertensive rat (SHR). Methods: 3H-ryanodine was used as a radioligand to analyse the binding in Sprague Dawley rat cardiac homogenate in following conditions: varied protein concentrations, different free calcium concentrations, different incubation time. The effect of sarcoplasmic reticulum purifying process and ryanodine competitive binding were also studied. Using these best conditions, SHR and control group (WKY) CSR ryanodine receptor were studied. Results: 1) There was a positive linear correlation between 3H-ryanodine binding and the homogenate protein concentration. 2) When the free calcium concentration was 30 μmol/L∼1 mmol/L, the 3H-ryanodine binding reached the maximum. While the free calcium concentration was lower than 1 μmol/L, there was no 3H-ryanodine binding. 3) The 3H-ryanodine binding kept increasing during incubation, from 0 to 60 min, and equilibrium reached by 90 min. 4) The ryanodine specifically inhibited 3H-ryanodine binding in cardiac homogenate. 5) During the sarcoplasmic reticulum purifying process, the 3H-ryanodine binding in a unit amount of cardiac homogenate decreased with the centrifugal force and times applied in centrifugation. 6) SHR and WKY CSR ryanodine receptor saturation curve and Scatchard analysis showed this method produced a very high level of specific binding, up to 45 nmol/L ryanodine, which inferred a single class of binding sites. The Bmax value of CSR ryanodine receptor in SHR left ventricle was significantly higher than that in WKY (P3H-ryanodine can be used as a radioligand to analyse the calcium release channel in cardiac homogenate, and ryanodine receptor may play an important role in hypertensive left ventricular remodeling process

  14. X-ray fluorescence with synchrotron radiation to elemental analysis of lead and calcium content of primary teeth

    International Nuclear Information System (INIS)

    Primary teeth were analyzed by micro-SRXRF. The aim of this study was to determine the elemental distribution of lead and calcium in different regions of primary incisor of children living in a notoriously contaminated area (Santo Amaro da Purificacao, Bahia State, Brazil). The measurements were performed in standard geometry of 45 deg. incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil).

  15. Effect of immobilization on urine calcium excretion in orthopedic patients with pelvic fracture treated by skin traction

    Directory of Open Access Journals (Sweden)

    Ali Derakhshan

    2015-03-01

    Full Text Available Objectives: To determine the effects on urine calcium excretion of immobilization by skin traction in patients with pelvic fracture. Methods: In a prospective study, a consecutive series of patients with pelvic fracture treated by skin traction were enrolled. Serum (calcium, phosphorous, alkaline phosphatase, sodium, potassium, uric acid, BUN, creatinine and fasting urine calcium, creatinine, sodium, potassium and uric acid were checked within 48 hours of hospitalization and at 7, 14 and 21 days of immobilization and then after 3 months of mobilization. Trends in changes of variables were recorded. Results: Fifty five patients were enrolled in this study; they were 45 (81.8% males and 10 (18.2% females with a mean age 19.4 ± 12.7 years. We found that serum levels of calcium (p = 0.004, phosphorous (p = 0.047 and alkaline phosphatase (p = 0.001 increased significantly during the 3 weeks of immobilization. In the same way, urine calcium/ urine creatinine ratio increased significantly in the study period (p = 0.004. No symptomatic renal stone formation was observed during the study period. Conclusions: Immobilization even in short term causes hypercalciuria in orthopedic patients. Although it is transient and improves with subsequent mobilization, it is needed to be considered specifically by the team caring for this group of patients.

  16. Stimulatory effects of maitotoxin on insulin release in insulinoma HIT cells: Role of calcium uptake and phosphoinositide breakdown

    International Nuclear Information System (INIS)

    In hamster insulinoma (HIT) cells, maitotoxin (MTX) induces a time-dependent and concentration-dependent release of insulin that requires the presence of extracellular calcium. The response is nearly completely blocked by cinnarizine and cadmium, but is not inhibited by the L-type calcium channel blocker nifedipine or by manganese. MTX induces 45Ca+ uptake in these cells in a dose-dependent mode, and the uptake is blocked with cinnarizine, nifedipine and cadmium, and is partially inhibited by manganese. MTX induces phosphoinositide breakdown in HIT cells, and the response is partially blocked by cadmium, but is not affected by nifedipine, cinnarizine or manganese. High concentrations of potassium ions also induce insulin release and calcium uptake in HIT cells. Both effects of potassium are blocked partially by nifedipine, cadmium and cinnarizine. High concentrations of potassium do not induce phosphoinositide breakdown in HIT cells. The results suggest that MTX-elicited release of insulin is attained by two mechanisms: (1) a nifedipine-sensitive action, which results from MTX-induced activation of L-type calcium channels, which can be mimicked with high potassium concentrations; and (2) a nifedipine-insensitive action, which may be initiated by the activation of phosphoinositide breakdown by MTX. Such an activation of phospholipase C would result in the formation of 1,4,5-inositol trisphosphate, a release of intracellular calcium and then release of insulin to the extracellular space. Cinnarizine is proposed to block both MTX-elicited mechanisms, the first by blockade of calcium channels and the second by blocking 1,4,5-inositol trisphosphate-induced release of internal calcium. Either mechanism alone appears capable of eliciting release of insulin

  17. Polarity Alteration of a Calcium Site Induces a Hydrophobic Interaction Network and Enhances Cel9A Endoglucanase Thermostability.

    Science.gov (United States)

    Wang, Hsiu-Jung; Hsiao, Yu-Yuan; Chen, Yu-Pei; Ma, Tien-Yang; Tseng, Ching-Ping

    2016-03-01

    Structural calcium sites control protein thermostability and activity by stabilizing native folds and changing local conformations. Alicyclobacillus acidocaldarius survives in thermal-acidic conditions and produces an endoglucanase Cel9A (AaCel9A) which contains a calcium-binding site (Ser465 to Val470) near the catalytic cleft. By superimposing the Ca(2+)-free and Ca(2+)-bounded conformations of the calcium site, we found that Ca(2+) induces hydrophobic interactions between the calcium site and its nearby region by driving a conformational change. The hydrophobic interactions at the high-B-factor region could be enhanced further by replacing the surrounding polar residues with hydrophobic residues to affect enzyme thermostability and activity. Therefore, the calcium-binding residue Asp468 (whose side chain directly ligates Ca(2+)), Asp469, and Asp471 of AaCel9A were separately replaced by alanine and valine. Mutants D468A and D468V showed increased activity compared with those of the wild type with 0 mM or 10 mM Ca(2+) added, whereas the Asp469 or Asp471 substitution resulted in decreased activity. The D468A crystal structure revealed that mutation D468A triggered a conformational change similar to that induced by Ca(2+) in the wild type and developed a hydrophobic interaction network between the calcium site and the neighboring hydrophobic region (Ala113 to Ala117). Mutations D468V and D468A increased 4.5°C and 5.9°C, respectively, in melting temperature, and enzyme half-life at 75°C increased approximately 13 times. Structural comparisons between AaCel9A and other endoglucanases of the GH9 family suggested that the stability of the regions corresponding to the AaCel9A calcium site plays an important role in GH9 endoglucanase catalysis at high temperature. PMID:26729722

  18. Investigation of function similarities between the sarcoplasmic reticulum and platelet calcium-dependent adenosinetriphosphatases with the inhibitors quercetin and calmidazolium

    International Nuclear Information System (INIS)

    The platelet and skeletal sarcoplasmic reticulum calcium-dependent adenosinetriphosphatases (Ca2+-ATPases) were functionally compared with respect to substrate activation by steady-state kinetic methods using the inhibitors quercetin and calmidazolium. Quercetin inhibited platelet and sarcoplasmic reticulum Ca2+-ATPase activities in a dose-dependent manner with IC50 values of 25 and 10 μM, respectively. Calmidazolium also inhibited platelet and sarcoplasmic reticulum Ca2+-ATPase activities, with half-maximal inhibition measured at 5 and 4 μM, respectively. Both inhibitors also affected the [45Ca] calcium transport activity of intact platelet microsomes at concentrations similar to those which reduced Ca2+-ATPase activity. These inhibitors were then used to examine substrate ligation by the platelet and sarcoplasmic reticulum calcium pump proteins. For both Ca2+-ATPase proteins, quercetin has an affinity for the E-Ca2 (fully ligated with respect to calcium at the exterior high-affinity calcium binding sites, unligated with respect to ATP) conformational state of the protein that is approximately 10-fold grater than for other conformational states in the hydrolytic cycle. Quercetin can thus be considered a competitive inhibitor of the calcium pump proteins with respect to ATP. In contrast to the effect of quercetin, calmidazolium interacts with the platelet and sarcoplasmic reticulum Ca2+-ATPases in an uncompetitive manner. The dissociation constants for this inhibitor for the different conformational states of the calcium pump proteins were similar, indicating that calmidazolium has equal affinity for all of the reaction intermediates probed. These observations indicate that the substrate ligation processes are similar for the two pump proteins. This supports the concept that the hydrolytic cycles of the two proteins are comparable

  19. Data for accelerated degradation of calcium phosphate surface-coated polycaprolactone and polycaprolactone/bioactive glass composite scaffolds

    OpenAIRE

    Poh, Patrina S.P.; Hutmacher, Dietmar W.; Holzapfel, Boris M; Solanki, Anu K.; Woodruff, Maria A.

    2016-01-01

    Polycaprolactone (PCL)-based composite scaffolds containing 50 wt% of 45S5 bioactive glass (45S5) or strontium-substituted bioactive glass (SrBG) particles were fabricated into scaffolds using melt-extrusion based additive manufacturing technique. Additionally, the PCL scaffolds were surface coated with a layer of calcium phosphate (CaP). For a comparison of the scaffold degradation, the scaffolds were then subjected to in vitro accelerated degradation by immersion in 5 M sodium hydroxide (Na...

  20. 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.

  1. 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)

  2. 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 ...

  3. 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

  4. 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

  5. Simultaneous measurements of magnesium, calcium and sodium influxes in perfused squid giant axons under membrane potential control.

    Science.gov (United States)

    Rojas, E; Taylor, R E

    1975-10-01

    1. Giant axons from the squids Dosidicus gigas, Loligo forbesi and Loligo vulgaris were internally perfused with 550 or 275 mM KF plus sucrose and bathed in artificial sea water containing 45Ca, 28Mg or mixtures of 45Ca-28Mg or 45Ca-22Na. Resting influxes and extra influxes during voltage-clamp pulses were measured by collecting and counting the internal perfusate. 2. For Dosidicus axons in 10 mM-CaCl2 the resting influx of calcium was 0-016 +/- 0-007 p-mole/cm2 sec and a linear function of external concentration. For two experiments in 10 and 84-7 mM-CaCl2, 100 nM tetrodotoxin had no effect. Resting calcium influx in 10 mM-CaCl2 was 0-017 +/- 0-013 p-mole/cm2 sec for Loligo axons. 3. With 55 mM-MgCl2 outside the average resting magnesium influx was 0-124 +/- 0-080 p-mole/cm2 sec for Loligo axons. Discarding one aberrant point the value is 0-105 +/- 0-046 which is not significantly different from the resting calcium influx for Dosidicus fibres in 55 mM-CaCl2, given as 0-094 p-mole/cm2 sec by the regression line shown in Fig. 1. In two experiments 150 nM tetrodotoxin had no effect. 4. With 430 mM-NaCl outside 100 nM tetrodotoxin reduced the average resting influx of sodium in Dosidicus axon from 27-7 +/- 4-5 to 25-1 +/- 6-2 p-mole/cm2 sec and for Loligo fibres in 460 mM-NaCl from 50-5 +/- 4 to 20 +/- 8 p-mole/cm2 sec. 5. Using depolarizing pulses of various durations, the extra calcium influx occurred in two phases. The early phase was eliminated by external application of tetrodotoxin. The results of analysis are consistent with, but do not rigorously demonstrate, the conclusion that the tetrodotoxin sensitive calcium entry is flowing through the normal sodium channels (cf. Baker, Hodgkin & Ridgway, 1971). 6. Measurements of extra influxes using 22Na and 45Ca simultaneously indicate that the time courses of tetrodotoxin sensitive calcium and sodium entry are similar but not necessarily identical. It is very doubtful that any significant calcium entry occurs before

  6. 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...

  7. 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...

  8. 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

  9. 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...

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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...

  15. 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...

  16. 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...

  17. 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.

  18. 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

  19. 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...

  20. 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.

  1. 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

  2. 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

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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.

  12. Chemical composition and dry matter digestibility of sugar cane oxide treated with calcium

    OpenAIRE

    C.O. Romão; G.G.P. Carvalho; V.M. Leite; Santos, A. S.; D.M.T. Chagas; O.L. Ribeiro; P.A. Oliveira; Magalhães, A F; A.J.V. Pires

    2014-01-01

    The aim of this study was to identify the most adequate level of calcium oxide (CaO) in the treatment of sugar cane by evaluating the chemical composition and in vitro digestibility of dry matter. The sugar cane was homogenized with CaO levels 0, 0.75, 1.5, 2.25, 3.0, 3.75 and 4.5%, in natura matter, for 24 hours. The dry matter and mineral matter increased, while the organic matter of the sugar cane decreased (P

  13. Calcium Sulfate Characterized by ChemCam/Curiosity at Gale Crater, Mars

    Science.gov (United States)

    Nachon, M.; Clegg, S. N.; Mangold, N.; Schroeder, S.; Kah, L. C.; Dromart, G.; Ollila, A.; Johnson, J. R.; Oehler, D. Z.; Bridges, J. C.; LeMouelic, S.; Forni, O.; Wiens, R. C.; Rapin, W.; Anderson, R. B.; Blaney, D. L.; Bell, J. F. , III; Clark, B.; Cousin, A.; Dyar, M. D.; Ehlmann, B.; Fabre, C.; Gasnault, O.; Grotzinger, J.; Lasue, J.; Lewin, E.; Leveille, R.; McLennan, S.; Maurice, S.; Meslin, P.-Y.; Rice, M.; Squyres, S. W.; Stack, K.; Sumner, D. Y.; Vaniman, D.; Wellington, D.

    2014-01-01

    Onboard the Mars Science Laboratory (MSL) Curiosity rover, the ChemCam instrument consists of :(1) a Laser-Induced Breakdown Spectrometer (LIBS) for elemental analysis of the targets [1;2] and (2) a Remote Micro Imager (RMI), for the imaging context of laser analysis [3]. Within the Gale crater, Curiosity traveled from Bradbury Landing through the Rocknest region and into Yellowknife Bay (YB). In the latter, abundant light-toned fracture-fill material were seen [4;5]. ChemCam analysis demonstrate that those fracture fills consist of calcium sulfates [6].

  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. 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

  5. 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 ...

  6. 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.

  7. 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.

  8. Effects of temperature and sodium carboxylate additives on mineralization of calcium oxalate in silica gel systems

    Institute of Scientific and Technical Information of China (English)

    OUYANG; Jianming; DENG; Suiping; LI; Xiangping; TAN; Yanh

    2004-01-01

    Lieske, J. C., Norris, R., Toback. F, G., Adhesion, internalization and metabolism of calcium oxalate monohydrate crystals by renal epithelial cells, Kidney Inertnational, 1997, 52: 1291-1301.[25]Mandel, N., Crystal-membrane interaction in kidney stone disease,J. Am. Soc. Nephrol., 1994, 5(supple 1): S37-S45.

  9. 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

  10. A model for the transfer of calcium and strontium to the fetus

    International Nuclear Information System (INIS)

    A biokinetic model has been developed for the transfer of calcium and strontium to the human fetus. For the mother, ICRP models were adapted for pregnancy to include increases in gastrointestinal absorption, urinary excretion and bone turnover rates. The fetus was modelled with blood, soft tissue and bone compartments. Fetal requirements for CA were determined by skeletal calcification and recycling between fetal and maternal blood was included. Daily transfer of Sr to the fetus was taken to be 0.6 times that of Ca. For acute intakes of 45Ca and 90Sr in late pregnancy at 36 weeks after conception, when maximum transfer occurs, the model predicts CF:CM ratios of 19 and 9, respectively. Corresponding committed doses to the red bone marrow of offspring would be greater than in adults by factors of about nine for 45Ca and about two for 90Sr. (author)

  11. 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

  12. 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

  13. 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

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

    Science.gov (United States)

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

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

  15. Calcium transport across the isolated oral epithelium of scleractinian corals

    Science.gov (United States)

    Wright, O. P.; Marshall, A. T.

    1991-07-01

    Oral epithelia were isolated from Lobophyllia temprichii and Plerogyra sinuosa and placed in Ussing chambers. Calcium flux was measured under open circuit and short circuit conditions using 45Ca. Only a small transepithelial potential of 1.5 mV was recorded under open circuit conditions and no effect on flux rates were observed when the preparation was short circuited. Unidirectional fluxes in single and paired experiments were consistently greater in the ectoderm to gastroderm direction than from gastroderm to ectoderm with net flux of Ca2+ frequently being more than 3x10-4 μEq mm-2 min-1. A small number of paired experiments showed that net flux of Ca2+ was reduced by Sr2+ and sodium azide but not by dinitrophenol. Unidirectional fluxes from ectoderm to gastroderm appeared to have maxima in the early and late parts of the day when recorded between 0900 and 2100 hrs. It is concluded that active transport of Ca2+ occurs across the isolated oral epitheia and that this may be an initial step in the process of keletal Ca2+ deposition.

  16. 45 Years with Design Methodology

    DEFF Research Database (Denmark)

    Andreasen, Mogens Myrup

    2011-01-01

    in my area. Therefore the use of ‘I’ is in a non-traditional form. The object of this article is the author’s Weltanschaung concerning design and designing as it has developed over a 45 years period as teacher and researcher. Three dimensions are treated in an attempt to answer the following...

  17. Self nanoemulsifying drug delivery system (SNEDDS) of rosuvastatin calcium: design, formulation, bioavailability and pharmacokinetic evaluation.

    Science.gov (United States)

    Balakumar, Krishnamoorthy; Raghavan, Chellan Vijaya; selvan, Natarajan Tamil; prasad, Ranganathan Hari; Abdu, Siyad

    2013-12-01

    The aim of the present study is to improve solubility and bioavailability of Rosuvastatin calcium using self nanoemulsifying drug delivery system (SNEDDS). Self emulsifying property of various oils including essential oils was evaluated with suitable surfactants and co-surfactants. Ternary phase diagrams were constructed based on Rosuvastatin calcium solubility analysis for optimizing the system. The prepared formulations were evaluated for self emulsifying time, robustness to dilution, droplet size determination and zeta potential analysis. The system was found to be robust in different pH media and dilution volume. The globule size of the optimized system was less than 200nm which could be an acceptable nanoemulsion size range. The zeta potential of the selected CN 7 SNEDDS formulation (cinnamon oil 30%; labrasol 60%; Capmul MCM C8 10%) was -29.5±0.63 with an average particle size distribution of 122nm. In vitro drug release studies showed remarkable increase in dissolution of CN7 SNEDDS compared to marketed formulation. In house developed HPLC method for determination of Rosuvastatin calcium in rat plasma was used in the bioavailability and pharmacokinetic evaluation. The relative bioavailability of self nanoemulsified formulation showed an enhanced bioavailability of 2.45 times greater than that of drug in suspension. The obtained plasma drug concentration data was processed with PKSolver 2.0 and it was best fit into the one compartment model. PMID:24012665

  18. Interaction of calcium with the human divalent metal-ion transporter-1

    International Nuclear Information System (INIS)

    Iron deficiency is the most prevalent micronutrient deficiency worldwide. Whereas dietary calcium is known to reduce the bioavailability of iron, the molecular basis of this interaction is not understood. We tested the hypothesis that divalent metal-ion transporter-1 (DMT1)-the principal or only mechanism by which nonheme iron is taken up at the intestinal brush border-is shared also by calcium. We expressed human DMT1 in RNA-injected Xenopus oocytes and examined its activity using radiotracer assays and the voltage clamp. DMT1 did not mediate 45Ca2+ uptake. Instead, we found that Ca2+ blocked the Fe2+-evoked currents and inhibited 55Fe2+ uptake in a noncompetitive manner (Ki ∼ 20 mM). The mechanism of inhibition was independent of voltage and did not involve intracellular Ca2+ signaling. The alkaline-earth metal ions Ba2+, Sr2+, and Mg2+ also inhibited DMT1-mediated iron-transport activity. We conclude that Ca2+ is a low-affinity noncompetitive inhibitor-but not a transported substrate-of DMT1, explaining in part the effect of high dietary calcium on iron bioavailability.

  19. Degradation of sulfated polysaccharide extracted from algal Laminaria japonica and its modulation on calcium oxalate crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang Jianming, E-mail: toyjm@jnu.edu.cn [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Wang Miao; Lu Peng; Tan Jin [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)

    2010-08-30

    Sulfated polysaccharide (LPS) extracted from alga Laminaria japonica was degraded by hydrogen peroxide (H{sub 2}O{sub 2}). The average molecular weight of LPS was apparently decreased from 172,000 to 9550 after degradation, while the proportion of sulfate groups (-OSO{sub 3}{sup -}) and carboxylic groups (-COO{sup -}) in the molecular chains of LPS were slightly decreased from 4.5% and 5.20% to 3.9% and 4.64%, respectively. The effects of degraded and natural LPS on formation of calcium oxalate (CaOxa) crystals were investigated in vitro using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), zeta-potential, and atomic absorption spectroscopy. LPS could increase the concentration of soluble Ca{sup 2+} ions in the solution, decrease the weight of precipitated CaOxa, and increase the negative value of zeta-potential of CaOxa crystals. LPS also inhibits the formation of thermodynamically stable calcium oxalate monohydrate (COM) crystals, while inducing and stabilizing metastable calcium oxalate dihydrate (COD) crystals. These results suggested that both degraded and natural LPS could decrease CaOxa crystallization, but the inhibition efficiency of the degraded LPS was clearly superior to that of the natural LPS. We expected this investigation would provide encouragement for further exploration into new drugs for the prevention and treatment of urolithiasis.

  20. Interaction of calcium with the human divalent metal-ion transporter-1

    Energy Technology Data Exchange (ETDEWEB)

    Shawki, Ali [Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, P.O. Box 670576, Cincinnati, OH 45267-0576 (United States); Mackenzie, Bryan, E-mail: bryan.mackenzie@uc.edu [Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, P.O. Box 670576, Cincinnati, OH 45267-0576 (United States)

    2010-03-12

    Iron deficiency is the most prevalent micronutrient deficiency worldwide. Whereas dietary calcium is known to reduce the bioavailability of iron, the molecular basis of this interaction is not understood. We tested the hypothesis that divalent metal-ion transporter-1 (DMT1)-the principal or only mechanism by which nonheme iron is taken up at the intestinal brush border-is shared also by calcium. We expressed human DMT1 in RNA-injected Xenopus oocytes and examined its activity using radiotracer assays and the voltage clamp. DMT1 did not mediate {sup 45}Ca{sup 2+} uptake. Instead, we found that Ca{sup 2+} blocked the Fe{sup 2+}-evoked currents and inhibited {sup 55}Fe{sup 2+} uptake in a noncompetitive manner (K{sub i} {approx} 20 mM). The mechanism of inhibition was independent of voltage and did not involve intracellular Ca{sup 2+} signaling. The alkaline-earth metal ions Ba{sup 2+}, Sr{sup 2+}, and Mg{sup 2+} also inhibited DMT1-mediated iron-transport activity. We conclude that Ca{sup 2+} is a low-affinity noncompetitive inhibitor-but not a transported substrate-of DMT1, explaining in part the effect of high dietary calcium on iron bioavailability.

  1. Degradation of sulfated polysaccharide extracted from algal Laminaria japonica and its modulation on calcium oxalate crystallization

    International Nuclear Information System (INIS)

    Sulfated polysaccharide (LPS) extracted from alga Laminaria japonica was degraded by hydrogen peroxide (H2O2). The average molecular weight of LPS was apparently decreased from 172,000 to 9550 after degradation, while the proportion of sulfate groups (-OSO3-) and carboxylic groups (-COO-) in the molecular chains of LPS were slightly decreased from 4.5% and 5.20% to 3.9% and 4.64%, respectively. The effects of degraded and natural LPS on formation of calcium oxalate (CaOxa) crystals were investigated in vitro using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), zeta-potential, and atomic absorption spectroscopy. LPS could increase the concentration of soluble Ca2+ ions in the solution, decrease the weight of precipitated CaOxa, and increase the negative value of zeta-potential of CaOxa crystals. LPS also inhibits the formation of thermodynamically stable calcium oxalate monohydrate (COM) crystals, while inducing and stabilizing metastable calcium oxalate dihydrate (COD) crystals. These results suggested that both degraded and natural LPS could decrease CaOxa crystallization, but the inhibition efficiency of the degraded LPS was clearly superior to that of the natural LPS. We expected this investigation would provide encouragement for further exploration into new drugs for the prevention and treatment of urolithiasis.

  2. 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...

  3. 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.

  4. 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

  5. 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

  6. 45 CFR 1304.50 - Program governance.

    Science.gov (United States)

    2010-10-01

    ... requirements of 45 CFR 1305.3; (iv) The program's philosophy and long- and short-range program goals and... program's philosophy and long- and short-range program goals and objectives (see 45 CFR 1304.51(a) and 45... (see 45 CFR 1301.2 for a definition of a delegate agency). (iii) Parent Committee. For...

  7. Effects of the hexahydroxyhexane myoinositol on bone uptake of radiocalcium in rats: Effect of inositol and vitamin D2 on bone uptake of 45Ca in rats

    International Nuclear Information System (INIS)

    The objective of this study was to investigate the effects of inositol and vitamin D2 on bone uptake of 45Ca in rats. The radioactive calcium was administered to young rats by orogastric intubation (2 μci/100 g body weight (b.wt.)) with inositol (20 mg/100 g b.wt) and/or vitamin D2 (500 IU/100g b.wt) to normal rats. Bone uptake of 45Ca was measured after 24 hours by standard technique. Inositol alone produced a 48% increase in calcium uptake. It is concluded that inositol significantly increases bone uptake to radioactive calcium (P>0.005). Simultaneous administration of vitamin D2 decreases the effect of inositol considerably, while vitamin D2 has no significant effect. (author)

  8. 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.

  9. 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

  10. 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)

  11. 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)

  12. 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...

  13. 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...

  14. 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)

  15. 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...

  16. 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...

  17. 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...

  18. 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.

  19. 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

  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. Dopamine receptors on adrenal chromaffin cells modulate calcium uptake and catecholamine release

    Energy Technology Data Exchange (ETDEWEB)

    Bigornia, L.; Suozzo, M.; Ryan, K.A.; Napp, D.; Schneider, A.S.

    1988-10-01

    The presence of dopamine-containing cells in sympathetic ganglia, i.e., small, intensely fluorescent cells, has been known for some time. However, the role of dopamine as a peripheral neurotransmitter and its mechanism of action are not well understood. Previous studies have demonstrated the presence of D2 dopamine receptors on the surface of bovine adrenal chromaffin cells using radioligand binding methods and dopamine receptor inhibition of catecholamine release from perfused adrenal glands. In the present study, we provide evidence confirming a role of dopamine receptors as inhibitory modulators of adrenal catecholamine release from bovine chromaffin cell cultures and further show that the mechanism of modulation involves inhibition of stimulated calcium uptake. Apomorphine gave a dose-dependent inhibition (IC50 = 1 microM) of 45Ca2+ uptake stimulated by either nicotine (10 microM) or membrane depolarization with an elevated K+ level (60 mM). This inhibition was reversed by a series of specific (including stereospecific) dopamine receptor antagonists: haloperidol, spiperone, sulpiride, and (+)-butaclamol, but not (-)-butaclamol. In addition, the calcium channel agonist Bay K 8644 was used to stimulate uptake of 45Ca2+ into chromaffin cells, and this uptake was also inhibited by the dopamine receptor agonist apomorphine. The combined results suggest that dopamine receptors on adrenal chromaffin cells alter Ca2+ channel conductance, which, in turn, modulates catecholamine release.

  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. 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

  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. 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

  11. 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.

  12. 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

  13. Effects of weak amplitude-modulated microwave fields on calcium efflux from awake cat cerebral cortex

    International Nuclear Information System (INIS)

    Calcium (45Ca2+) efflux was studied from preloaded cortex in cats immobilized under local anesthesia, and exposed to a 3.0-mW/cm2 450-MHz field, sinusoidally amplitude modulated at 16 Hz modulation depth 85%). Tissue dosimetry showed a field of 33 V/m in the interhemispheric fissure (rate of energy deposition 0.29 W/kg). Field exposure lasted 60 min. By comparison with controls, efflux curves from field exposed brains were disrupted by waves of increased 45Ca2+ efflux. These waves were irregular in amplitude and duration, but many exhibited periods of 20-30 min. They continued into the postexposure period. Binomial probability analysis indicates that the field-exposed efflux curves constitute a different population from controls at a confidence level of 0.96. In about 70% of cases, initiation of field exposure was followed by increased end-tidal CO2 excretion for about 5 min. However, hypercapnea induced by hypoventilation did not elicit increased 45Ca2+ efflux. Thus this increase with exposure does not appear to arise as a secondary effect of raised cerebral CO2 levels. Radioactivity measurements in cortical samples after superfusion showed 45Ca2+ penetration at about 1.7 mm/hr, consistent with diffusion of the ion in free solution

  14. 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)

  15. 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 ...

  16. 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...

  17. 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

  18. Growth, grain yield and calcium, potassium and magnesium accumulation in common bean plants as related to calcium nutrition

    Directory of Open Access Journals (Sweden)

    Lucas da Silva Domingues

    2016-04-01

    Full Text Available The objective of this work was to evaluate the plant growth and grain yield characteristics and the accumulation of calcium, potassium and magnesium in the leaves and grains of common bean cultivars grown with different calcium concentrations in the nutrient solution. Two experiments were conducted with nutrient solutions in a soilless system in a greenhouse. In the first experiment, five calcium concentrations (1.10, 1.65, 2.20, 2.75 and 3.30 mmol L-1 and three common bean cultivars (Iraí, BRS Expedito and Carioca were evaluated. Higher calcium concentrations (2.20, 2.75, 3.30, 3.85, 4.40 and 4.95 mmol L-1and two common bean cultivars (BRS Expedito and Carioca were tested in the second experiment. Dry mass of the shoot and root, grain yield and calcium accumulation in the leaves and grains increased linearly in common bean plants supplied with calcium concentrations between 2.20 and 4.95 mmol L-1. The high calcium concentration did not reduce the accumulation of calcium, potassium and magnesium in the leaves and grains. Common bean plants grown with high calcium concentrations present higher dry mass of the shoot and root, high grain yield and high calcium concentration in the leaves and grains.

  19. A new role for follicle-stimulating hormone in the regulation of calcium flux in Sertoli cells: Inhibition of Na+/Ca++ exchange

    International Nuclear Information System (INIS)

    Elucidation of mechanisms regulating intracellular calcium levels in steroidogenic tissues is important for understanding control of cellular function. We have previously described FSH receptor-mediated flux of 45Ca++ into cultured rat Sertoli cells and receptor-enriched proteoliposomes via voltage-sensitive and voltage-independent calcium channels. In the present study, we report heretofore unrecognized inhibitory effects of FSH on Na+/Ca++ exchange in these two systems. An outwardly directed Na+ gradient, developed by preincubating Sertoli cell monolayers in buffer made hypertonic with NaCl, resulted in uptake of 45Ca++ that was unaffected by calcium channel blocking agents, ruthenium red or methoxyverapamil, but was enhanced by ouabain, a specific inhibitor of Na+/K(+)-ATPase. Sodium-dependent 45Ca++ flux into Sertoli cells was inhibited in a concentration-related manner by increased extracellular Na+ (up to 135 mM). FSH consistently and reproducibly (28.9 +/- 3.8%, 10 separate assays) reduced sodium-dependent 45Ca++ influx in the absence or presence of ouabain. A lesser effect on Na+/Ca++ exchange was seen when Li+ replaced Na+ in the preincubation buffer, and a marked reduction occurred when Sertoli cells were incubated in buffer containing KCl, presumably due to membrane depolarization. FSH-sensitive Na+/45Ca++ exchange was also observed when using FSH receptor-enriched proteoliposomes. Our earlier calcium channel studies indicated that FSH affects Ca++ entry into Sertoli cells via a receptor-mediated process. The results reported here demonstrate that the interaction of FSH with its receptor is associated with changes in Na+/Ca++ exchange as well, and suggest that this activity may also be involved in regulating intracellular free Ca++ levels in the Sertoli cell

  20. Heavy metals in fish scales: accumulation and effects on calcium regulation in the mummichog, Fundulus heteroclitus L

    International Nuclear Information System (INIS)

    The scales of Fundulus heteroclitus were used to study the effects of heavy metals on fish calcification. Fish were subjected to laboratory zinc- or cadmium-exposure and scales analyzed for calcium, phosphorus, metals, and organic content. In regenerating scales, both metals caused reductions in scale calcium and phosphorus during the early stages of calcification. In later stages, phosphorus was elevated by cadmium. In calcium-45 uptake experiments metal-specific results were observed. Cd affected calcification indirectly by reducing Ca2+ uptake by the gills while Zn, acted directly at the site of calcification and was accumulated by the scales. Experiments with isolated gills in vitro using metabolic inhibitors suggested that initial Ca2+ uptake occurs by facilitated diffusion and that Cd2+ ions are effective at displacing Ca2+ ions from the calcium carrier. In saltwater fish, Ca2+ transport across the basolateral membranes of gill chloride cells is partially dependent on a metal-insensitive Ca2+-ATPase but most Ca2+ uptake appears to occur passively. In isolated scales, Ca2+ transport was energy dependent and was inhibited by both Cd and Zn