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Sample records for active magnesium chelatase

  1. ATPases and phosphate exchange activities in magnesium chelatase subunits of Rhodobacter sphaeroides.

    PubMed

    Hansson, M; Kannangara, C G

    1997-11-25

    Three separate proteins, BchD, BchH, and BchI, together with ATP, insert magnesium into protoporphyrin IX. An analysis of ATP utilization by the subunits revealed the following: BchH catalyzed ATP hydrolysis at the rate of 0.9 nmol per min per mg of protein. BchI and BchD, tested individually, had no ATPase activity but, when combined, hydrolyzed ATP at the rate of 117.9 nmol/min per mg of protein. Magnesium ions were required for the ATPase activities of both BchH and BchI+D, and these activities were inhibited 50% by 2 mM o-phenanthroline. BchI additionally catalyzed a phosphate exchange reaction from ATP and ADP. We conclude that ATP hydrolysis by BchI+D is required for an activation step in the magnesium chelatase reaction, whereas ATPase activity of BchH and the phosphate exchange activity of BchI participate in subsequent reactions leading to the insertion of Mg2+ into protoporphyrin IX.

  2. 1-N-histidine phosphorylation of ChlD by the AAA(+) ChlI2 stimulates magnesium chelatase activity in chlorophyll synthesis.

    PubMed

    Sawicki, Artur; Zhou, Shuaixiang; Kwiatkowski, Kathrin; Luo, Meizhong; Willows, Robert D

    2017-06-09

    Magnesium chelatase (Mg-chelatase) inserts magnesium into protoporphyrin during the biosynthesis of chlorophyll and bacteriochlorophyll. Enzyme activity is reconstituted by forming two separate preactivated complexes consisting of a GUN4/ChlH/protoporphyrin IX substrate complex and a ChlI/ChlD enzyme 'motor' complex. Formation of the ChlI/ChlD complex in both Chlamydomonas reinhardtii and Oryza sativa is accompanied by phosphorylation of ChlD by ChlI, but the orthologous protein complex from Rhodobacter capsulatus, BchI/BchD, gives no detectable phosphorylation of BchD. Phosphorylation produces a 1-N-phospho-histidine within ChlD. Proteomic analysis indicates that phosphorylation occurs at a conserved His residue in the C-terminal integrin I domain of ChlD. Comparative analysis of the ChlD phosphorylation with enzyme activities of various ChlI/ChlD complexes correlates the phosphorylation by ChlI2 with stimulation of Mg-chelatase activity. Mutation of the H641 of CrChlD to E641 prevents both phosphorylation and stimulation of Mg-chelatase activity, confirming that phosphorylation at H641 stimulates Mg-chelatase. The properties of ChlI2 compared with ChlI1 of Chlamydomonas and with ChlI of Oryza, shows that ChlI2 has a regulatory role in Chlamydomonas. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  3. Reduced chlorophyll biosynthesis in heterozygous barley magnesium chelatase mutants.

    PubMed

    Braumann, Ilka; Stein, Nils; Hansson, Mats

    2014-05-01

    Chlorophyll biosynthesis is initiated by magnesium chelatase, an enzyme composed of three proteins, which catalyzes the insertion of Mg2+ into protoporphyrin IX to produce Mg-protoporphyrin IX. In barley (Hordeum vulgare L.) the three proteins are encoded by Xantha-f, Xantha-g and Xantha-h. Two of the gene products, XanH and XanG, belong to the structurally conserved family of AAA+ proteins (ATPases associated with various cellular activities) and form a complex involving six subunits of each protein. The complex functions as an ATP-fueled motor of the magnesium chelatase that uses XanF as substrate, which is the catalytic subunit responsible for the insertion of Mg2+ into protoporphyrin IX. Previous studies have shown that semi-dominant Xantha-h mutations result in non-functional XanH subunits that participate in the formation of inactive AAA complexes. In the present study, we identify severe mutations in the barley mutants xantha-h.38, -h.56 and -h.57. A truncated form of the protein is seen in xantha-h.38, whereas no XanH is detected in xantha-h.56 and -h.57. Heterozygous mutants show a reduction in chlorophyll content by 14-18% suggesting a slight semi-dominance of xantha-h.38, -h.56 and -h.57, which otherwise have been regarded as recessive mutations.

  4. Reconstitution of an active magnesium chelatase enzyme complex from the bchI, -D, and -H gene products of the green sulfur bacterium Chlorobium vibrioforme expressed in Escherichia coli.

    PubMed

    Petersen, B L; Jensen, P E; Gibson, L C; Stummann, B M; Hunter, C N; Henningsen, K W

    1998-02-01

    Magnesium-protoporphyrin chelatase, the first enzyme unique to the (bacterio)chlorophyll-specific branch of the porphyrin biosynthetic pathway, catalyzes the insertion of Mg2+ into protoporphyrin IX. Three genes, designated bchI, -D, and -H, from the strictly anaerobic and obligately phototrophic green sulfur bacterium Chlorobium vibrioforme show a significant level of homology to the magnesium chelatase-encoding genes bchI, -D, and -H and chlI, -D, and -H of Rhodobacter sphaeroides and Synechocystis strain PCC6803, respectively. These three genes were expressed in Escherichia coli; the subsequent purification of overproduced BchI and -H proteins on an Ni2+-agarose affinity column and denaturation of insoluble BchD protein in 6 M urea were required for reconstitution of Mg-chelatase activity in vitro. This work therefore establishes that the magnesium chelatase of C. vibrioforme is similar to the magnesium chelatases of the distantly related bacteria R. sphaeroides and Synechocystis strain PCC6803 with respect to number of subunits and ATP requirement. In addition, reconstitution of an active heterologous magnesium chelatase enzyme complex was obtained by combining the C. vibrioforme BchI and -D proteins and the Synechocystis strain PCC6803 ChlH protein. Furthermore, two versions, with respect to the N-terminal start of the bchI gene product, were expressed in E. coli, yielding ca. 38- and ca. 42-kDa versions of the BchI protein, both of which proved to be active. Western blot analysis of these proteins indicated that two forms of BchI, corresponding to the 38- and the 42-kDa expressed proteins, are also present in C. vibrioforme.

  5. The magnesium-chelatase in developing cucumber cotyledons

    SciTech Connect

    Walker, C.J.; Weinstein, J.D. )

    1990-05-01

    Mg-chelatase in chloroplasts catalyzes the insertion of Mg into protoporphyrin. This step is the first in the tetrapyrrole pathway unique to chlorophyll biosynthesis. Mg-chelatase was assayed in semi-green cucumber cotyledons by an adaptation of the method of Fuesler at al, (1984) Plant Physiol. 74, 928-933. Plastid intactness was essential for Mg-chelatase activity. The estimated Km for the protoporphyrin substrate was between 0.5 and 1.0 {mu}M. In the presence of 4 mM ATP and an ATP regenerating system, activities of 500 pmol Mg-Protoporphyrin/mg protein/20 min were routinely recorded. In greening cotyledons, the specific activity of the Mg-chelatase increased steadily until the chlorophyll content of the plastids reached about 30 nmol/mg plastid protein, at which point further greening caused a decrease in Mg-chelatase activity. The total heme content of the plastids also rose with greening and paralleled the increase in Mg-chelatase activity. The regulation of heme levels and Mg-chelatase activity in greening cotyledons will be discussed. Substrate specificity studies showed that mesoporphyrin and deuteroporphyrin were active substrates for Mg chelation. The Mg-chelatase was not inhibited by its product, Mg-Protoporphyrin, but was inhibited by N-methyl mesoporphyrin (I{sub 50} = 2.5 {mu}M). Mg-chelatase activity was also measured in fully mature pea and corn chloroplasts (grown under diurnal light); the specific activities were comparable with those in cucumber.

  6. Three separate proteins constitute the magnesium chelatase of Rhodobacter sphaeroides.

    PubMed

    Willows, R D; Gibson, L C; Kanangara, C G; Hunter, C N; von Wettstein, D

    1996-01-15

    The insertion of magnesium into protoporphyrin IX is the first step unique to chlorophyll production and is catalyzed by magnesium chelatase. The Rhodobacter sphaeroides genes, bchI and bchD together, and bchH alone, were cloned and expressed with the pET3a vector in Escherichia coli strain BL21 (DE3). The 40-kDa BchI protein was synthesized in greater abundance compared to the 70-kDa BchD protein when both were expressed together from the same plasmid. The production of large amounts of the 140-kDa BchH protein in E. coli was accompanied by an accumulation of protoporphyrin IX. The accumulated protoporphyrin IX was bound specifically to BchH in an approximate molar ratio of 1:1. All three recombinant proteins were soluble; BchH was monomeric, Bchl was dimeric, while BchD appeared to be polymeric with a molecular mass of approximately 550 kDa. The BchH and BchI proteins were purified to apparent homogeneity while BchD was separated from BchI and partially purified. Magnesium was inserted into protoporphyrin IX and deuteroporphyrin by combining these three proteins in the presence of ATP. One monomer of BchH to one dimer of BchI gave the optimal magnesium chelatase activity and the activity was dependent on the amount of partially purified BchD added to the assay at the optimum BchH:BchI ratio. The reaction was dissected into two parts with an activation step requiring BchI, BchD, and Mg2+-ATP, and a metal-insertion step which in addition requires Mg2+, protoporphyrin IX, and BchH. The stoichiometric binding of protoporphyrin IX to BchH in vitro is direct evidence for BchH carrying out such a role in vivo whereas the other two proteins are involved in ATP activation and magnesium insertion.

  7. Catalytic turnover triggers exchange of subunits of the magnesium chelatase AAA+ motor unit.

    PubMed

    Lundqvist, Joakim; Braumann, Ilka; Kurowska, Marzena; Müller, André H; Hansson, Mats

    2013-08-16

    The ATP-dependent insertion of Mg(2+) into protoporphyrin IX is the first committed step in the chlorophyll biosynthetic pathway. The reaction is catalyzed by magnesium chelatase, which consists of three gene products: BchI, BchD, and BchH. The BchI and BchD subunits belong to the family of AAA+ proteins (ATPases associated with various cellular activities) and form a two-ring complex with six BchI subunits in one layer and six BchD subunits in the other layer. This BchID complex is a two-layered trimer of dimers with the ATP binding site located at the interface between two neighboring BchI subunits. ATP hydrolysis by the BchID motor unit fuels the insertion of Mg(2+) into the porphyrin by the BchH subunit. In the present study, we explored mutations that were originally identified in semidominant barley (Hordeum vulgare L.) mutants. The resulting recombinant BchI proteins have marginal ATPase activity and cannot contribute to magnesium chelatase activity although they apparently form structurally correct complexes with BchD. Mixing experiments with modified and wild-type BchI in various combinations showed that an exchange of BchI subunits in magnesium chelatase occurs during the catalytic cycle, which indicates that dissociation of the complex may be part of the reaction mechanism related to product release. Mixing experiments also showed that more than three functional interfaces in the BchI ring structure are required for magnesium chelatase activity.

  8. Magnesium-protoporphyrin chelatase of Rhodobacter sphaeroides: reconstitution of activity by combining the products of the bchH, -I, and -D genes expressed in Escherichia coli.

    PubMed

    Gibson, L C; Willows, R D; Kannangara, C G; von Wettstein, D; Hunter, C N

    1995-03-14

    Magnesium-protoporphyrin chelatase lies at the branch point of the heme and (bacterio)chlorophyll biosynthetic pathways. In this work, the photosynthetic bacterium Rhodobacter sphaeroides has been used as a model system for the study of this reaction. The bchH and the bchI and -D genes from R. sphaeroides were expressed in Escherichia coli. When cell-free extracts from strains expressing BchH, BchI, and BchD were combined, the mixture was able to catalyze the insertion of Mg into protoporphyrin IX in an ATP-dependent manner. This was possible only when all three genes were expressed. The bchH, -I, and -D gene products are therefore assigned to the Mg chelatase step in bacteriochlorophyll biosynthesis. The mechanism of the Mg chelation reaction and the implications for chlorophyll biosynthesis in plants are discussed.

  9. Magnesium chelatase subunit D from pea: characterization of the cDNA, heterologous expression of an enzymatically active protein and immunoassay of the native protein.

    PubMed

    Luo, M; Weinstein, J D; Walker, C J

    1999-12-01

    Mg-chelatase catalyzes the insertion of Mg into protoporphyrin and lies at the branchpoint of heme and (bacterio)chlorophyll synthesis. In prokaryotes, three genes--BchI, D and H--encode subunits for Mg-chelatase. In higher plants, homologous cDNAs for the I, D and H subunits have been characterized. Since the N-terminal half of the D subunit is homologous to the I subunit, the C-terminal portion of the pea D was used for antigen production. The antibody recognized the chloroplast D subunit and was used to demonstrate that this subunit associated with the membranes in the presence of MgCl2. The antibody immunoprecipitated the native protein and inhibited Mg-chelatase activity. Expression in Escherichia coli with a construct for the full-length protein (minus the putative transit peptide) resulted in induction of 24.5 kDa (major) and 89 kDa (minor) proteins which could only be solubilized in 6 M urea. However, when host cells were co-transformed with expression vectors for the full-length D subunit and for the 70 kDa HSP chaperonin protein, a substantial portion of the 89 kDa protein was expressed in a soluble form which was active in a Mg-chelatase reconstitution assay.

  10. Further characterization of the magnesium chelatase in isolated developing cucumber chloroplasts

    SciTech Connect

    Walker, C.J.; Weinstein, J.D. )

    1991-04-01

    Mg-chelatase catalyzes the first step unique to the chlorophyll branch of tetrapyrrole biosynthesis, namely the insertion of Mg into protoporphyrin IX (Proto). Mg-chelatase was assayed in intact chloroplasts from semi-green cucumber (Cucumis sativus, cv Sumter) cotyledons. In the presence of Proto and MgATP, enzyme activity was linear for 50 minutes. Plastid intactness was directly related to (and necessary for) Mg-chelatase activity. Uncouplers and ionophores did not inhibit Mg-chelatase in the presence of ATP. The nonhydrolyzable ATP analogs, {beta},{gamma}-methylene ATP and adenylylimidodiphosphate, could not sustain Mg-chelatase activity alone and were inhibitory in the presence of ATP (I{sub 50} 10 and 3 millimolar, respectively). Mg-chelatase was also inhibited by N-ethylmaleimide (I{sub 50}, 50 micromolar) and the metal ion chelators 2,2{prime}-dipyridyl and 1,10 phenanthroline (but not to the same degree by their nonchelating analogs). In addition to Proto, the following porphyrins acted as Mg-chelatase substrates, giving comparable specific activities: deuteroporphyrin, mesoporphyrin, 2-ethyl, 4-vinyl Proto and 2-vinyl, 4-ethyl Proto. Mg-chelatase activity and freely exchangeable heme levels increased steadily with greening, reaching a maximum and leveling off after 15 hours in the light. Exogenous protochlorophyllide, chlorophyllide, heme, and Mg-Proto had no measurable effect on Mg-chelatase activity. The potent ferrochelatase inhibitors, N-methylmesoporphyrin and N-methylprotoporphyrin, inhibited Mg-chelatase at micromolar concentrations.

  11. Characterization of three homologs of the large subunit of the magnesium chelatase from Chlorobaculum tepidum and interaction with the magnesium protoporphyrin IX methyltransferase.

    PubMed

    Johnson, Ethan T; Schmidt-Dannert, Claudia

    2008-10-10

    Green bacteria synthesize several types of (bacterio)chlorophylls for the assembly of functional photosynthetic reaction centers and antenna complexes. A distinctive feature of green bacteria compared with other photosynthetic microbes is that their genomes contain multiple homologs of the large subunit (BchH) of the magnesium chelatase which is a three-subunit enzyme complex (BchH, BchD, and BchI) that inserts magnesium into protoporphyrin IX as the first committed step of (bacterio)chlorophyll biosynthesis. There is speculation that the additional BchH homologs may regulate the biosynthesis of each type of chlorophyll, although the biochemical properties of the different magnesium chelatase complexes from a single species of green bacteria have not yet been compared. In this study, we investigated the activities of all three chelatase complexes from the green sulfur bacterium Chlorobaculum tepidum and interactions with the next enzyme in the pathway, magnesium protoporphyrin IX methyltransferase (BchM). Although all three chelatase complexes insert magnesium into protoporphyrin IX, the activities range by a factor of 10(5). Further, there are differences in the interactions between the BchH homologs and BchM; two of the subunits increase the methyltransferase activity by 30-60%, and the third decreases it by 30%. Expression of the chelatase complexes alone and together with BchM in Escherichia coli overproducing protoporphyrin IX suggests that the chelatase is the rate-limiting enzyme. We observed that BchM uses protoporphyrin IX without bound metal as a substrate. Our results conflict with expectations generated by previous gene inactivation studies and suggest a complex regulation of chlorophyll biosynthesis in green bacteria.

  12. Kinetic analyses of the magnesium chelatase provide insights into the mechanism, structure, and formation of the complex.

    PubMed

    Sawicki, Artur; Willows, Robert D

    2008-11-14

    The metabolic pathway known as (bacterio)chlorophyll biosynthesis is initiated by magnesium chelatase (BchI, BchD, BchH). This first step involves insertion of magnesium into protoporphyrin IX (proto), a process requiring ATP hydrolysis. Structural information shows that the BchI and BchD subunits form a double hexameric enzyme complex, whereas BchH binds proto and can be purified as BchH-proto. We utilized the Rhodobacter capsulatus magnesium chelatase subunits using continuous magnesium chelatase assays and treated the BchD subunit as the enzyme with both BchI and BchH-proto as substrates. Michaelis-Menten kinetics was observed with the BchI subunit, whereas the BchH subunit exhibited sigmoidal kinetics (Hill coefficient of 1.85). The BchI.BchD complex had intrinsic ATPase activity, and addition of BchH greatly increased ATPase activity. This was concentration-dependent and gave sigmoidal kinetics, indicating there is more than one binding site for the BchH subunit on the BchI.BchD complex. ATPase activity was approximately 40-fold higher than magnesium chelatase activity and continued despite cessation of magnesium chelation, implying one or more secondary roles for ATP hydrolysis and possibly an as yet unknown switch required to terminate ATPase activity. One of the secondary roles for BchH-stimulated ATP hydrolysis by a BchI.BchD complex is priming of BchH to facilitate correct binding of proto to BchH in a form capable of participating in magnesium chelation. This porphyrin binding is the rate-limiting step in catalysis. These data suggest that ATP hydrolysis by the BchI.BchD complex causes a series of conformational changes in BchH to effect substrate binding, magnesium chelation, and product release.

  13. Three semidominant barley mutants with single amino acid substitutions in the smallest magnesium chelatase subunit form defective AAA+ hexamers.

    PubMed

    Hansson, A; Willows, R D; Roberts, T H; Hansson, M

    2002-10-15

    Many enzymes of the bacteriochlorophyll and chlorophyll biosynthesis pathways have been conserved throughout evolution, but the molecular mechanisms of the key steps remain unclear. The magnesium chelatase reaction is one of these steps, and it requires the proteins BchI, BchD, and BchH to catalyze the insertion of Mg(2+) into protoporphyrin IX upon ATP hydrolysis. Structural analyses have shown that BchI forms hexamers and belongs to the ATPases associated with various cellular activities (AAA(+)) family of proteins. AAA(+) proteins are Mg(2+)-dependent ATPases that normally form oligomeric ring structures in the presence of ATP. By using ATPase-deficient BchI subunits, we demonstrate that binding of ATP is sufficient to form BchI oligomers. Further, ATPase-deficient BchI proteins can form mixed oligomers with WT BchI. The formation of BchI oligomers is not sufficient for magnesium chelatase activity when combined with BchD and BchH. Combining WT BchI with ATPase-deficient BchI in an assay disrupts the chelatase reaction, but the presence of deficient BchI does not inhibit ATPase activity of the WT BchI. Thus, the ATPase of every WT segment of the hexamer is autonomous, but all segments of the hexamer must be capable of ATP hydrolysis for magnesium chelatase activity. We suggest that ATP hydrolysis of each BchI within the hexamer causes a conformational change of the hexamer as a whole. However, hexamers containing ATPase-deficient BchI are unable to perform this ATP-dependent conformational change, and the magnesium chelatase reaction is stalled in an early stage.

  14. BchJ and BchM interact in a 1 : 1 ratio with the magnesium chelatase BchH subunit of Rhodobacter capsulatus.

    PubMed

    Sawicki, Artur; Willows, Robert D

    2010-11-01

    Substrate channeling between the enzymatic steps in the (bacterio)chlorophyll biosynthetic pathway catalyzed by magnesium chelatase (BchI/ChlI, BchD/ChlD and BchH/ChlH subunits) and S-adenosyl-L-methionine:magnesium-protoporphyrin IX O-methyltransferase (BchM/ChlM) has been suggested. This involves delivery of magnesium-protoporphyrin IX from the BchH/ChlH subunit of magnesium chelatase to BchM/ChlM. Stimulation of BchM/ChlM activity by BchH/ChlH has previously been shown, and physical interaction of the two proteins has been demonstrated. In plants and cyanobacteria, there is an added layer of complexity, as Gun4 serves as a porphyrin (protoporphyrin IX and magnesium-protoporphyrin IX) carrier, but this protein does not exist in anoxygenic photosynthetic bacteria. BchJ may play a similar role to Gun4 in Rhodobacter, as it has no currently assigned function in the established pathway. Purified recombinant Rhodobacter capsulatus BchJ and BchM were found to cause a shift in the equilibrium amount of Mg-protoporphyrin IX formed in a magnesium chelatase assay. Analysis of this shift revealed that it was always in a 1 : 1 ratio with either of these proteins and the BchH subunit of the magnesium chelatase. The establishment of the new equilibrium was faster with BchM than with BchJ in a coupled magnesium chelatase assay. BchJ bound magnesium-protoporphyrin IX or formed a ternary complex with BchH and magnesium-protoporphyrin IX. These results suggest that BchJ may play a role as a general magnesium porphyrin carrier, similar to one of the roles of GUN4 in oxygenic organisms.

  15. An organelle-free assay for pea chloroplast Mg-chelatase: Resolution of the activity into soluble and membrane bound fractions

    SciTech Connect

    Walker, C.J.; Weinstein, J.D. )

    1991-05-01

    Mg-chelatase, which catalyzes the insertion of magnesium into protoporphyrin, lies at the branchpoint of heme and chlorophyll biosynthesis in chloroplasts. Since magnesium chelation is the first step unique to chlorophyll synthesis, one would expect this step to be highly regulated. However, to date little is known about the enzymology or regulation of Mg-chelatase due mostly to an inability to assay it's activity outside of the intact plastid. Here the authors report the first truly in vitro i.e. organelle-free, assay for Mg-chelatase. Mg-chelatase activity in intact pea chloroplasts which is 3 to 4 fold higher than in cucumber chloroplasts, survived chloroplast lysis and could be fractionated, by centrifugation, into supernatant and pellet components. Both of these fractions were required to reconstitute Mg-chelatase activity and both were inactivated by boiling; indicating that the enzyme is composed of soluble and membrane bound protein(s). The specific activity of the reconstituted system was typically 1 nmol Mg-Deuteroporphyrin/h/mg protein and activity was linear for at least 60 min under our assay conditions. ATP and magnesium were required for Mg-chelatase activity. The soluble component could be fractionated with ammonium sulfate. The product of the reaction was confirmed fluorometrically as the magnesium chelate of the porphyrin substrate. Crude separation of chloroplast membranes into thylakoids and envelopes, suggested that the membrane-bound component of Mg-chelatase is probably located in the envelope.

  16. Expression of the chlI, chlD, and chlH genes from the Cyanobacterium synechocystis PCC6803 in Escherichia coli and demonstration that the three cognate proteins are required for magnesium-protoporphyrin chelatase activity.

    PubMed

    Jensen, P E; Gibson, L C; Henningsen, K W; Hunter, C N

    1996-07-12

    Magnesium-protoporphyrin chelatase catalyzes the first step unique to chlorophyll synthesis: the insertion of Mg2+ into protoporphyrin IX. Genes from Synechocystis sp. PCC6803 with homology to the bchI and bchD genes of Rhodobacter sp. were cloned using degenerate oligonucleotides. The function of these genes, putatively encoding subunits of magnesium chelatase, was established by overexpression in Escherichia coli, including the overexpression of Synechocystis chlH, previously cloned as a homolog of the Rhodobacter bchH gene. The combined cell-free extracts were able to catalyze the insertion of Mg2+ into protoporphyrin IX in an ATP-dependent manner and only when the products of all three genes were present. The ChlH, ChlI, and ChlD gene products are therefore assigned to the magnesium chelatase step in chlorophyll a biosynthesis in Synechocystis PCC6803. The primary structure of the Synechocystis ChlD protein reveals some interesting features; the N-terminal half of the protein shows 40-41% identity to Rhodobacter BchI and Synechocystis ChlI, whereas the C-terminal half displays 33% identity to Rhodobacter BchD. This suggests a functional as well as an evolutionary relationship between the "I" and "D" genes.

  17. Interplay between an AAA module and an integrin I domain may regulate the function of magnesium chelatase.

    PubMed

    Fodje, M N; Hansson, A; Hansson, M; Olsen, J G; Gough, S; Willows, R D; Al-Karadaghi, S

    2001-08-03

    In chlorophyll biosynthesis, insertion of Mg(2+) into protoporphyrin IX is catalysed in an ATP-dependent reaction by a three-subunit (BchI, BchD and BchH) enzyme magnesium chelatase. In this work we present the three-dimensional structure of the ATP-binding subunit BchI. The structure has been solved by the multiple wavelength anomalous dispersion method and refined at 2.1 A resolution to the crystallographic R-factor of 22.2 % (R(free)=24.5 %). It belongs to the chaperone-like "ATPase associated with a variety of cellular activities" (AAA) family of ATPases, with a novel arrangement of domains: the C-terminal helical domain is located behind the nucleotide-binding site, while in other known AAA module structures it is located on the top. Examination by electron microscopy of BchI solutions in the presence of ATP demonstrated that BchI, like other AAA proteins, forms oligomeric ring structures. Analysis of the amino acid sequence of subunit BchD revealed an AAA module at the N-terminal portion of the sequence and an integrin I domain at the C terminus. An acidic, proline-rich region linking these two domains is suggested to contribute to the association of BchI and BchD by binding to a positively charged cleft at the surface of the nucleotide-binding domain of BchI. Analysis of the amino acid sequences of BchI and BchH revealed integrin I domain-binding sequence motifs. These are proposed to bind the integrin I domain of BchD during the functional cycle of magnesium chelatase, linking porphyrin metallation by BchH to ATP hydrolysis by BchI. An integrin I domain and an acidic and proline-rich region have been identified in subunit CobT of cobalt chelatase, clearly demonstrating its homology to BchD. These findings, for the first time, provide an insight into the subunit organisation of magnesium chelatase and the homologous colbalt chelatase.

  18. Rhodobacter capsulatus magnesium chelatase subunit BchH contains an oxygen sensitive iron-sulfur cluster.

    PubMed

    Sirijovski, Nick; Mamedov, Fikret; Olsson, Ulf; Styring, Stenbjörn; Hansson, Mats

    2007-12-01

    Magnesium chelatase is the first unique enzyme of the bacteriochlorophyll biosynthetic pathway. It consists of three subunits (BchI, BchD, and BchH). Amino acid sequence analysis of the Rhodobacter capsulatus BchH revealed a novel cysteine motif (393CX2CX3CX14C) that was found in only six other proteobacteria (CX2CX3CX11-14C). The cysteine motif is likely to coordinate an unprecedented [Fe-S] cluster. Purified BchH demonstrated absorbance in the 460 nm region. This absorbance was abolished in BchH proteins with alanine substitutions at positions Cys396 and Cys414. These modified proteins were also EPR silent. In contrast, wild type BchH protein in the reduced state showed EPR signals resembling those of a [4Fe-4S] cluster with rhombic symmetry and g values at 1.90, 1.93, and 2.09, superimposed with a [3Fe-4S] cluster centered at g = 2.02. The [3Fe-4S] signal was observed independently of the [4Fe-4S] signal under oxidizing conditions. Mg-chelatase activity assays showed that the cluster is not catalytic. We suggest that the [4Fe-4S] and [3Fe-4S] signals originate from a single coordination site on the monomeric BchH protein and that the [4Fe-4S] cluster is sensitive to oxidation. It is speculated that the cluster participates in the switching between aerobic and anaerobic life of the proteobacteria.

  19. In vitro assay of the chlorophyll biosynthetic enzyme Mg-chelatase: Resolution of the activity into soluble and membrane-bound fractions

    SciTech Connect

    Walker, C.J.; Weinstein, J.D. )

    1991-07-01

    The first committed step in chlorophyll synthesis is the Mg-chelatase-catalyzed insertion of magnesium into protoporphyrin IX. Since iron insertion into protoporphyrin leads to heme formation, Mg-chelatase lies at the branch point of heme and chlorophyll synthesis in chloroplasts. Little is known about the enzymology or regulation of Mg-chelatase, as it has been assayed only in intact cucumber chloroplasts. In this report we describe an in vitro assay for Mg-chelatase. Mg-chelatase activity in intact pea chloroplasts was 3- to 4-fold higher than in cucumber chloroplasts. This activity survived chloroplast lysis and could be fractionated by centrifugation into supernatant and pellet components. Both of these fractions were required to reconstitute Mg-chelatase activity, and both were inactivated by boiling indicating that the enzyme is composed of soluble and membrane-bound protein(s). The product of the reaction was confirmed fluorometrically as the magnesium chelate of the porphyrin substrate. The specific activity of the reconstituted system was typically 1 nmol of Mg-deuteroporphyrin per h per mg of protein, and activity was linear for at least 60 min under our assay conditions. ATP and magnesium were required for Mg-chelatase activity and the enzymen was sensitive to the sulfhydryl reagent N-ethylmaleimide (I{sub 50}, 20 {mu}M). Broken and reconstituted cucumber chloroplasts were unable to maintain Mg-chelatase activity. However, the cucumber supernatant fraction was active when combined with the pellet fraction of peas; the converse was not true, which suggested that the cucumber pellet was the component that lost activity during lysis.

  20. ATP-induced conformational dynamics in the AAA+ motor unit of magnesium chelatase.

    PubMed

    Lundqvist, Joakim; Elmlund, Hans; Wulff, Ragna Peterson; Berglund, Lisa; Elmlund, Dominika; Emanuelsson, Cecilia; Hebert, Hans; Willows, Robert D; Hansson, Mats; Lindahl, Martin; Al-Karadaghi, Salam

    2010-03-10

    Mg-chelatase catalyzes the first committed step of the chlorophyll biosynthetic pathway, the ATP-dependent insertion of Mg(2+) into protoporphyrin IX (PPIX). Here we report the reconstruction using single-particle cryo-electron microscopy of the complex between subunits BchD and BchI of Rhodobacter capsulatus Mg-chelatase in the presence of ADP, the nonhydrolyzable ATP analog AMPPNP, and ATP at 7.5 A, 14 A, and 13 A resolution, respectively. We show that the two AAA+ modules of the subunits form a unique complex of 3 dimers related by a three-fold axis. The reconstructions demonstrate substantial differences between the conformations of the complex in the presence of ATP and ADP, and suggest that the C-terminal integrin-I domains of the BchD subunits play a central role in transmitting conformational changes of BchI to BchD. Based on these data a model for the function of magnesium chelatase is proposed.

  1. Heterologous expression of the Rhodobacter capsulatus BchI, -D, and -H genes that encode magnesium chelatase subunits and characterization of the reconstituted enzyme.

    PubMed

    Willows, R D; Beale, S I

    1998-12-18

    Magnesium chelatase inserts Mg2+ into protoporphyrin IX in the chlorophyll and bacteriochlorophyll biosynthetic pathways. In photosynthetic bacteria, the products of three genes, bchI, bchD, and bchH, are required for magnesium chelatase activity. These genes from Rhodobacter capsulatus were cloned separately into expression plasmids pET3a and pET15b. The pET15b constructs produced NH2-terminally His6-tagged proteins. All proteins were highly expressed and were purified to near homogeneity. The BchI and BchH proteins were soluble. BchD proteins were insoluble, inactive inclusion bodies that were renatured by rapid dilution from 6 M urea. The presence of BchI in the solution into which the urea solution of BchD was diluted increased the yield of active BchD. A molar ratio of 1 BchI:1 BchD was sufficient for maximum renaturation of BchD. All of the proteins were active in the magnesium chelatase assay except His-tagged BchI, which was inactive and inhibited in incubations containing non-His-tagged BchI. Expressed BchH proteins contained tightly bound protoporphyrin IX, and they were susceptible to inactivation by light. Maximum magnesium chelatase activity per mol of BchD occurred at a stoichiometry of 4 BchI:1 BchD. The optimum reaction pH was 8.0. The reaction exhibited Michaelis-Menten kinetics with respect to protoporphyrin IX and BchH.

  2. Magnesium insertion by magnesium chelatase in the biosynthesis of zinc bacteriochlorophyll a in an aerobic acidophilic bacterium Acidiphilium rubrum.

    PubMed

    Masuda, T; Inoue, K; Masuda, M; Nagayama, M; Tamaki, A; Ohta, H; Shimada, H; Takamiya, K

    1999-11-19

    To elucidate the mechanism for formation of zinc-containing bacteriochlorophyll a in the photosynthetic bacterium Acidiphilium rubrum, we isolated homologs of magnesium chelatase subunits (bchI, -D, and -H). A. rubrum bchI and -H were encoded by single genes located on the clusters bchP-orf168-bchI-bchD-orf320-crtI and bchF-N-B-H-L as in Rhodobacter capsulatus, respectively. The deduced sequences of A. rubrum bchI, -D, and -H had overall identities of 59. 8, 40.5, and 50.7% to those from Rba. capsulatus, respectively. When these genes were introduced into bchI, bchD, and bchH mutants of Rba. capsulatus for functional complementation, all mutants were complemented with concomitant synthesis of bacteriochlorophyll a. Analyses of bacteriochlorophyll intermediates showed that A. rubrum cells accumulate magnesium protoporphyrin IX monomethyl ester without detectable accumulation of zinc protoporphyrin IX or its monomethyl ester. These results indicate that a single set of magnesium chelatase homologs in A. rubrum catalyzes the insertion of only Mg(2+) into protoporphyrin IX to yield magnesium protoporphyrin IX monomethyl ester. Consequently, it is most likely that zinc-containing bacteriochlorophyll a is formed by a substitution of Zn(2+) for Mg(2+) at a step in the bacteriochlorophyll biosynthesis after formation of magnesium protoporphyrin IX monomethyl ester.

  3. Five glutamic acid residues in the C-terminal domain of the ChlD subunit play a major role in conferring Mg(2+) cooperativity upon magnesium chelatase.

    PubMed

    Brindley, Amanda A; Adams, Nathan B P; Hunter, C Neil; Reid, James D

    2015-11-10

    Magnesium chelatase catalyzes the first committed step in chlorophyll biosynthesis by inserting a Mg(2+) ion into protoporphyrin IX in an ATP-dependent manner. The cyanobacterial (Synechocystis) and higher-plant chelatases exhibit a complex cooperative response to free magnesium, while the chelatases from Thermosynechococcus elongatus and photosynthetic bacteria do not. To investigate the basis for this cooperativity, we constructed a series of chimeric ChlD proteins using N-terminal, central, and C-terminal domains from Synechocystis and Thermosynechococcus. We show that five glutamic acid residues in the C-terminal domain play a major role in this process.

  4. Nanomechanical and thermophoretic analyses of the nucleotide-dependent interactions between the AAA+ subunits of magnesium chelatase

    SciTech Connect

    Adams, Nathan B. P.; Vasilev, Cvetelin; Brindley, Amanda A.; Hunter, C. Neil

    2016-04-30

    In chlorophyll biosynthesis, the magnesium chelatase enzyme complex catalyzes the insertion of a Mg2+ ion into protoporphyrin IX. Prior to this event, two of the three subunits, the AAA+ proteins ChlI and ChlD, form a ChlID–MgATP complex. We used microscale thermophoresis to directly determine dissociation constants for the I-D subunits from Synechocystis, and to show that the formation of a ChlID–MgADP complex, mediated by the arginine finger and the sensor II domain on ChlD, is necessary for the assembly of the catalytically active ChlHID–MgATP complex. The N-terminal AAA+ domain of ChlD is essential for complex formation, but some stability is preserved in the absence of the C-terminal integrin domain of ChlD, particularly if the intervening polyproline linker region is retained. Single molecule force spectroscopy (SMFS) was used to determine the factors that stabilize formation of the ChlID–MgADP complex at the single molecule level; ChlD was attached to an atomic force microscope (AFM) probe in two different orientations, and the ChlI subunits were tethered to a silica surface; the probability of subunits interacting more than doubled in the presence of MgADP, and we show that the N-terminal AAA+ domain of ChlD mediates this process, in agreement with the microscale thermophoresis data. Analysis of the unbinding data revealed a most probable interaction force of around 109 pN for formation of single ChlID–MgADP complexes. Finally, these experiments provide a quantitative basis for understanding the assembly and function of the Mg chelatase complex.

  5. Nanomechanical and thermophoretic analyses of the nucleotide-dependent interactions between the AAA+ subunits of magnesium chelatase

    DOE PAGES

    Adams, Nathan B. P.; Vasilev, Cvetelin; Brindley, Amanda A.; ...

    2016-04-30

    In chlorophyll biosynthesis, the magnesium chelatase enzyme complex catalyzes the insertion of a Mg2+ ion into protoporphyrin IX. Prior to this event, two of the three subunits, the AAA+ proteins ChlI and ChlD, form a ChlID–MgATP complex. We used microscale thermophoresis to directly determine dissociation constants for the I-D subunits from Synechocystis, and to show that the formation of a ChlID–MgADP complex, mediated by the arginine finger and the sensor II domain on ChlD, is necessary for the assembly of the catalytically active ChlHID–MgATP complex. The N-terminal AAA+ domain of ChlD is essential for complex formation, but some stability ismore » preserved in the absence of the C-terminal integrin domain of ChlD, particularly if the intervening polyproline linker region is retained. Single molecule force spectroscopy (SMFS) was used to determine the factors that stabilize formation of the ChlID–MgADP complex at the single molecule level; ChlD was attached to an atomic force microscope (AFM) probe in two different orientations, and the ChlI subunits were tethered to a silica surface; the probability of subunits interacting more than doubled in the presence of MgADP, and we show that the N-terminal AAA+ domain of ChlD mediates this process, in agreement with the microscale thermophoresis data. Analysis of the unbinding data revealed a most probable interaction force of around 109 pN for formation of single ChlID–MgADP complexes. Finally, these experiments provide a quantitative basis for understanding the assembly and function of the Mg chelatase complex.« less

  6. Magnesium chelatase from Rhodobacter sphaeroides: initial characterization of the enzyme using purified subunits and evidence for a BchI-BchD complex.

    PubMed

    Gibson, L C; Jensen, P E; Hunter, C N

    1999-01-15

    The enzyme magnesium-protoporphyrin IX chelatase (Mg chelatase) catalyses the insertion of Mg into protoporphyrin IX, the first committed step in (bacterio)chlorophyll biosynthesis. In the photosynthetic bacterium Rhodobacter sphaeroides, this reaction is catalysed by the products of the bchI, bchD and bchH genes. These genes have been expressed in Escherichia coli so that the BchI, BchD and BchH proteins are produced with N-terminal His6 affinity tags, which has led to the production of large amounts of highly purified, highly active Mg chelatase subunits from a single chromatography step. Furthermore, BchD has been purifed free of contamination with the chaperone GroEL, which had proven to be a problem in the past. BchD, present largely as an insoluble protein in E. coli, was purified in 6 M urea and refolded by addition of BchI, MgCl2 and ATP, yielding highly active protein. BchI/BchD mixtures prepared in this way were used in conjunction with BchH to determine the kinetic parameters of R. sphaeroides Mg chelatase for its natural substrates. We have been able to demonstrate for the first time that BchI and BchD form a complex, and that Mg2+ and ATP are required to establish and maintain this complex. Gel filtration data suggest that BchI and BchD form a complex of molecular mass 200 kDa in the presence of Mg2+ and ATP. Our data suggest that, in vivo, BchD is only folded correctly and maintained in its correct conformation in the presence of BchI, Mg2+ and ATP.

  7. Magnesium chelatase: association with ribosomes and mutant complementation studies identify barley subunit Xantha-G as a functional counterpart of Rhodobacter subunit BchD.

    PubMed

    Kannangara, C G; Vothknecht, U C; Hansson, M; von Wettstein, D

    1997-03-18

    Magnesium chelatase catalyses the insertion of Mg2+ into protoporphyrin and is found exclusively in organisms which synthesise chlorophyll or bacteriochlorophyll. Soluble protein preparations containing >10 mg protein/ml, obtained by gentle lysis of barley plastids and Rhodobacter sphaeroplasts, inserted Mg2+ into deuteroporphyrin IX in the presence of ATP at rates of 40 and 8 pmoles/mg protein per min, respectively. With barley extracts optimal activity was observed with 40 mM Mg2+. The activity was inhibited by micromolar concentrations of chloramphenicol. Mutations in each of three genetic loci, Xantha-f, -g and -h, in barley destroyed the activity. However, Mg-chelatase activity was reconstituted in vitro by combining pairwise the plastid stroma protein preparations from non-leaky xantha-f -g and -h mutants. This establishes that, as in Rhodobacter, three proteins are required for the insertion of magnesium into protoporphyrin IX in barley. These three proteins, Xantha-F, -G and -H, are referred to as Mg-chelatase subunits and they appear to exist separate from each other in vivo. Active preparations from barley and Rhodobacter yielded pellet and supernatant fractions upon centrifugation for 90 min at 272,000 x g. The pellet and the supernatant were inactive when assayed separately, but when they were combined activity was restored. Differential distribution of the Mg-chelatase subunits in the fractions was established by in vitro complementation assays using stroma protein from the xantha-f, -g, and -h mutants. Xantha-G protein was confined to the pellet fraction, while Xantha-H was confined to the supernatant. Reconstitution assays using purified recombinant BchH, BchI and partially purified BchD revealed that the pellet fraction from Rhodobacter contained the BchD subunit. The pellet fractions from both barley and Rhodobacter contained ribosomes and had an A260:A280 ratio of 1.8. On sucrose density gradients both Xantha-G and BchD subunits migrated with the

  8. EM single particle analysis of the ATP-dependent BchI complex of magnesium chelatase: an AAA+ hexamer.

    PubMed

    Willows, R D; Hansson, A; Birch, D; Al-Karadaghi, S; Hansson, M

    2004-01-01

    BchI, belonging to the AAA+ -protein family, forms the enzyme magnesium chelatase together with BchD and BchH. This enzyme catalyses the insertion of Mg2+ into protoporphyrin IX upon ATP hydrolysis. Previous studies have indicated that BchI forms ATP-dependent complexes and it is a member of the AAA+ -protein family (ATPases associated with various cellular activities) and it was suggested based on structural homology that the BchI formed hexameric complexes. AAA+ -proteins are Mg2+ -dependent ATPases that normally form oligomeric ring complexes in the presence of ATP. Single particle analysis of fully formed ring complexes of BchI observed by negative staining EM indicate that the BchI has strong 6- and 2-fold rotational symmetries and a weaker 4-fold rotational symmetry which are reminiscent of DNA helicase. A 2D average of the fully formed BchI-ATP ring complex is presented here from images of the complex obtained from negative staining EM. Other complexes are also observed in the EM micrographs and the class averages of these are indicative of the fragility and dynamic nature of the BchI complex which has been reported and they are suggestive of partially circular complexes with six or less protomers per particle. The resolution of the average circular complex is estimated at approximately 30A and it is similar in shape and size to an atomic resolution hexameric model of BchI rendered at 30A.

  9. Substrate-binding model of the chlorophyll biosynthetic magnesium chelatase BchH subunit.

    PubMed

    Sirijovski, Nickolche; Lundqvist, Joakim; Rosenbäck, Matilda; Elmlund, Hans; Al-Karadaghi, Salam; Willows, Robert D; Hansson, Mats

    2008-04-25

    Photosynthetic organisms require chlorophyll and bacteriochlorophyll to harness light energy and to transform water and carbon dioxide into carbohydrates and oxygen. The biosynthesis of these pigments is initiated by magnesium chelatase, an enzyme composed of BchI, BchD, and BchH proteins, which catalyzes the insertion of Mg(2+) into protoporphyrin IX (Proto) to produce Mg-protoporphyrin IX. BchI and BchD form an ATP-dependent AAA(+) complex that transiently interacts with the Proto-binding BchH subunit, at which point Mg(2+) is chelated. In this study, controlled proteolysis, electron microscopy of negatively stained specimens, and single-particle three-dimensional reconstruction have been used to probe the structure and substrate-binding mechanism of the BchH subunit to a resolution of 25A(.) The apo structure contains three major lobe-shaped domains connected at a single point with additional densities at the tip of two lobes termed the "thumb" and "finger." With the independent reconstruction of a substrate-bound BchH complex (BchH.Proto), we observed a distinct conformational change in the thumb and finger subdomains. Prolonged proteolysis of native apo-BchH produced a stable C-terminal fragment of 45 kDa, and Proto was shown to protect the full-length polypeptide from degradation. Fitting of a truncated BchH polypeptide reconstruction identified the N- and C-terminal domains. Our results show that the N- and C-terminal domains play crucial roles in the substrate-binding mechanism.

  10. Cloning, subcellular localization and expression of CHL1, a subunit of magnesium-chelatase in soybean.

    PubMed

    Nakayama, M; Masuda, T; Sato, N; Yamagata, H; Bowler, C; Ohta, H; Shioi, Y; Takamiya, K

    1995-10-04

    Mg-insertion is the first committed step in chlorophyll synthesis and is catalyzed by Mg-chelatase. In photosynthetic bacteria, bchI gene product was suggested to be a subunit of Mg-chelatase. We isolated a bchI homolog from a soybean cDNA library and designated it as chlI. CHLI consisted of 421 amino acid residues and the sequence exhibited a high similarity to other BchI homologs. CHLI contained an ATP-binding motif found in other BchI homologs. CHLI was localized in the soluble fraction in soybean chloroplasts, suggesting that it was a stromal subunit of Mg-chelatase. chlI mRNA in cell culture (SB-P) of soybean was reversibly induced by light.

  11. The chlorophyll-deficient golden leaf mutation in cucumber is due to a single nucleotide substitution in CsChlI for magnesium chelatase I subunit.

    PubMed

    Gao, Meiling; Hu, Liangliang; Li, Yuhong; Weng, Yiqun

    2016-10-01

    The cucumber chlorophyll-deficient golden leaf mutation is due to a single nucleotide substitution in the CsChlI gene for magnesium chelatase I subunit which plays important roles in the chlorophyll biosynthesis pathway. The Mg-chelatase catalyzes the insertion of Mg(2+) into the protoporphyrin IX in the chlorophyll biosynthesis pathway, which is a protein complex encompassing three subunits CHLI, CHLD, and CHLH. Chlorophyll-deficient mutations in genes encoding the three subunits have played important roles in understanding the structure, function and regulation of this important enzyme. In an EMS mutagenesis population, we identified a chlorophyll-deficient mutant C528 with golden leaf color throughout its development which was viable and able to set fruits and seeds. Segregation analysis in multiple populations indicated that this leaf color mutation was recessively inherited and the green color showed complete dominance over golden color. Map-based cloning identified CsChlI as the candidate gene for this mutation which encoded the CHLI subunit of cucumber Mg-chelatase. The 1757-bp CsChlI gene had three exons and a single nucleotide change (G to A) in its third exon resulted in an amino acid substitution (G269R) and the golden leaf color in C528. This mutation occurred in the highly conserved nucleotide-binding domain of the CHLI protein in which chlorophyll-deficient mutations have been frequently identified. The mutant phenotype, CsChlI expression pattern and the mutated residue in the CHLI protein suggested the mutant allele in C528 is unique among mutations identified so far in different species. This golden leaf mutant not only has its potential in cucumber breeding, but also provides a useful tool in understanding the CHLI function and its regulation in the chlorophyll biosynthesis pathway as well as chloroplast development.

  12. Crystallization and preliminary X-ray analysis of the Rhodobacter capsulatus magnesium chelatase BchI subunit.

    PubMed

    Willows, R D; Hansson, M; Beale, S I; Laurberg, M; Al-Karadaghi, S

    1999-03-01

    The Rhodobacter capsulatus BchI protein is one of three subunits of Mg chelatase, the enzyme which catalyzes the first committed step of chlorophyll and bacteriochlorophyll biosynthesis. The BchI protein was produced with an inducible T7 RNA polymerase expression system in Escherichia coli. The protein was purified from the soluble cell-extract fraction and crystallized from polyethylene glycol solution. The crystals diffract to a minimum Bragg spacing of 2.1 A. The space group is P63 with unit-cell dimensions a = b = 90.6, c = 84.1 A.

  13. Phosphorylation of GENOMES UNCOUPLED 4 Alters Stimulation of Mg Chelatase Activity in Angiosperms1[OPEN

    PubMed Central

    Hochheuser, Caroline; Fufezan, Christian; Heinze, Laura

    2016-01-01

    GENOMES UNCOUPLED 4 (GUN4) is a positive regulator of light-dependent chlorophyll biosynthesis. GUN4 activates Mg chelatase (MgCh) that catalyzes the insertion of an Mg2+ ion into protoporphyrin IX. We show that Arabidopsis (Arabidopsis thaliana) GUN4 is phosphorylated at Ser 264 (S264), the penultimate amino acid residue at the C terminus. While GUN4 is preferentially phosphorylated in darkness, phosphorylation is reduced upon accumulation of Mg porphyrins. Expression of a phosphomimicking GUN4(S264D) results in an incomplete complementation of the white gun4-2 null mutant and a chlorotic phenotype comparable to gun4 knockdown mutants. Phosphorylated GUN4 has a reduced stimulatory effect on MgCh in vitro and in vivo but retains its protein stability and tetrapyrrole binding capacity. Analysis of GUN4 found in oxygenic photosynthetic organisms reveals the evolution of a C-terminal extension, which harbors the phosphorylation site of GUN4 expressed in angiosperms. Homologs of GUN4 from Synechocystis and Chlamydomonas lack the conserved phosphorylation site found in a C-terminal extension of angiosperm GUN4. Biochemical studies proved the importance of the C-terminal extension for MgCh stimulation and inactivation of GUN4 by phosphorylation in angiosperms. An additional mechanism regulating MgCh activity is proposed. In conjunction with the dark repression of 5-aminolevulinic acid synthesis, GUN4 phosphorylation minimizes the flow of intermediates into the Mg branch of the tetrapyrrole metabolic pathway for chlorophyll biosynthesis. PMID:27688621

  14. The Magnesium-Chelatase H Subunit Binds Abscisic Acid and Functions in Abscisic Acid Signaling: New Evidence in Arabidopsis1[W][OA

    PubMed Central

    Wu, Fu-Qing; Xin, Qi; Cao, Zheng; Liu, Zhi-Qiang; Du, Shu-Yuan; Mei, Chao; Zhao, Chen-Xi; Wang, Xiao-Fang; Shang, Yi; Jiang, Tao; Zhang, Xiao-Feng; Yan, Lu; Zhao, Rui; Cui, Zi-Ning; Liu, Rui; Sun, Hai-Li; Yang, Xin-Ling; Su, Zhen; Zhang, Da-Peng

    2009-01-01

    Using a newly developed abscisic acid (ABA)-affinity chromatography technique, we showed that the magnesium-chelatase H subunit ABAR/CHLH (for putative abscisic acid receptor/chelatase H subunit) specifically binds ABA through the C-terminal half but not the N-terminal half. A set of potential agonists/antagonists to ABA, including 2-trans,4-trans-ABA, gibberellin, cytokinin-like regulator 6-benzylaminopurine, auxin indole-3-acetic acid, auxin-like substance naphthalene acetic acid, and jasmonic acid methyl ester, did not bind ABAR/CHLH. A C-terminal C370 truncated ABAR with 369 amino acid residues (631–999) was shown to bind ABA, which may be a core of the ABA-binding domain in the C-terminal half. Consistently, expression of the ABAR/CHLH C-terminal half truncated proteins fused with green fluorescent protein (GFP) in wild-type plants conferred ABA hypersensitivity in all major ABA responses, including seed germination, postgermination growth, and stomatal movement, and the expression of the same truncated proteins fused with GFP in an ABA-insensitive cch mutant of the ABAR/CHLH gene restored the ABA sensitivity of the mutant in all of the ABA responses. However, the effect of expression of the ABAR N-terminal half fused with GFP in the wild-type plants was limited to seedling growth, and the restoring effect of the ABA sensitivity of the cch mutant was limited to seed germination. In addition, we identified two new mutant alleles of ABAR/CHLH from the mutant pool in the Arabidopsis Biological Resource Center via Arabidopsis (Arabidopsis thaliana) Targeting-Induced Local Lesions in Genomes. The abar-2 mutant has a point mutation resulting in the N-terminal Leu-348→Phe, and the abar-3 mutant has a point mutation resulting in the N-terminal Ser-183→Phe. The two mutants show altered ABA-related phenotypes in seed germination and postgermination growth but not in stomatal movement. These findings support the idea that ABAR/CHLH is an ABA receptor and reveal

  15. Evolution in a family of chelatases facilitated by the introduction of active site asymmetry and protein oligomerization

    PubMed Central

    Romão, Célia V.; Ladakis, Dimitrios; Lobo, Susana A. L.; Carrondo, Maria A.; Brindley, Amanda A.; Deery, Evelyne; Matias, Pedro M.; Pickersgill, Richard W.; Saraiva, Lígia M.; Warren, Martin J.

    2011-01-01

    The class II chelatases associated with heme, siroheme, and cobalamin biosynthesis are structurally related enzymes that insert a specific metal ion (Fe2+ or Co2+) into the center of a modified tetrapyrrole (protoporphyrin or sirohydrochlorin). The structures of two related class II enzymes, CbiXS from Archaeoglobus fulgidus and CbiK from Salmonella enterica, that are responsible for the insertion of cobalt along the cobalamin biosynthesis pathway are presented in complex with their metallated product. A further structure of a CbiK from Desulfovibrio vulgaris Hildenborough reveals how cobalt is bound at the active site. The crystal structures show that the binding of sirohydrochlorin is distinctly different to porphyrin binding in the protoporphyrin ferrochelatases and provide a molecular overview of the mechanism of chelation. The structures also give insights into the evolution of chelatase form and function. Finally, the structure of a periplasmic form of Desulfovibrio vulgaris Hildenborough CbiK reveals a novel tetrameric arrangement of its subunits that are stabilized by the presence of a heme b cofactor. Whereas retaining colbaltochelatase activity, this protein has acquired a central cavity with the potential to chaperone or transport metals across the periplasmic space, thereby evolving a new use for an ancient protein subunit. PMID:21173279

  16. Color formation in nitrite-free dried hams as related to Zn-protoporphyrin IX and Zn-chelatase activity.

    PubMed

    Parolari, Giovanni; Benedini, Riccardo; Toscani, Tania

    2009-08-01

    The development of red pigment Zn-protoporphyrin IX (ZPP) in nitrite-free Parma hams was investigated in 5 leg muscles at several stages of processing and the activity of muscle Zn-chelatase was concurrently assayed for its potential role in ZPP formation. A steady increase of the pigment was observed throughout the manufacturing stages at mild temperatures while no development was observed during the prior cold resting phase. The enzyme was partly inactivated according to a muscle-dependent pattern, resulting in similar ZPP contents, hence color, in finished hams. It is concluded that enzyme-dependent synthesis of ZPP in nitrite-free dried hams contributes to color development, enabling muscles in dried hams to become more similar in redness than in green thighs. Therefore, checking raw meat for the enzyme content may be a means to control color formation in nitrite-free dry-cured meat derivatives.

  17. The magnesium chelation step in chlorophyll biosynthesis

    SciTech Connect

    Weinstein, J.D.

    1991-01-01

    The biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins and lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX. Insertion of iron leads to heme, while insertion of magnesium leads to chlorophyll. The Mg-chelatase from intact cucumber chloroplasts has been characterized with regard to substrate specificity, regulation, ATP requirement, and a requirement for intact chloroplasts. Mg-chelatase was isolated from maize, barley and peas and characterized in order to circumvent the intact chloroplast requirement of cucumber Mg-chelatase. Pea Mg-chelatase activity is higher than cucumber Mg-chelatase activity, and lacks the requirement for intact chloroplasts. Studies on isolated pea Mg-chelatase have shown more cofactors are required for the reaction than are seen with ferrochelatase, indicating a greater opportunity for regulatory control of this pathway. Two of the cofactors are proteins, and there appears to be a requirement for a protease-sensitive component which is outside the outer envelope. We are developing a continuous spectrophotometric assay for Mg-chelatase activity, and an assay for free heme which has shown heme efflux from intact chloroplasts. 18 refs. (MHB)

  18. Mechanism and regulation of Mg-chelatase.

    PubMed Central

    Walker, C J; Willows, R D

    1997-01-01

    Mg-chelatase catalyses the insertion of Mg into protoporphyrin IX (Proto). This seemingly simple reaction also is potentially one of the most interesting and crucial steps in the (bacterio)chlorophyll (Bchl/Chl)-synthesis pathway, owing to its position at the branch-point between haem and Bchl/Chl synthesis. Up until the level of Proto, haem and Bchl/Chl synthesis share a common pathway. However, at the point of metal-ion insertion there are two choices: Mg2+ insertion to make Bchl/Chl (catalysed by Mg-chelatase) or Fe2+ insertion to make haem (catalysed by ferrochelatase). Thus the relative activities of Mg-chelatase and ferrochelatase must be regulated with respect to the organism's requirements for these end products. How is this regulation achieved? For Mg-chelatase, the recent design of an in vitro assay combined with the identification of Bchl-biosynthetic enzyme genes has now made it possible to address this question. In all photosynthetic organisms studied to date, Mg-chelatase is a three-component enzyme, and in several species these proteins have been cloned and expressed in an active form. The reaction takes place in two steps, with an ATP-dependent activation followed by an ATP-dependent chelation step. The activation step may be the key to regulation, although variations in subunit levels during diurnal growth may also play a role in determining the flux through the Bchl/Chl and haem branches of the pathway. PMID:9359397

  19. Mg-chelatase of tobacco: identification of a Chl D cDNA sequence encoding a third subunit, analysis of the interaction of the three subunits with the yeast two-hybrid system, and reconstitution of the enzyme activity by co-expression of recombinant CHL D, CHL H and CHL I.

    PubMed

    Papenbrock, J; Gräfe, S; Kruse, E; Hänel, F; Grimm, B

    1997-11-01

    Mg-protoporphyrin IX chelatase catalyzes insertion of the magnesium ion into protoporphyrin IX, the last common intermediate precursor in chlorophyll and heme biosynthesis, to form Mg-protoporphyrin IX. In Rhodobacter sphaeroides, and Synechocystis, the three open reading frames bchD/chID, bchH/chIH and bchI/chII encode proteins which are required for in vitro Mg-chelatase activity. In higher plants also, three proteins are necessary for the Mg chelation, and genes homologous to bchH and bchI have been isolated previously. In this study, a novel tobacco cDNA sequence homologous to bchD is isolated and initially characterized. Together with the tobacco clones encoding the other two subunits, full-length cDNAs are now available for the first time for all three subunits of one plant species. The CHL D polypeptide deduced from the open reading frame encodes a protein of 758 aa (82.9 kDa) with an amino terminal extension that resembles a plastid transit peptide. Sequence comparison of tobacco CHL D revealed similarities to the D subunit of Rhodobacter and Synechocystis of 44% and 75%. The amino terminal half of CHL D shows significant similarity (46%) to the entire CHL I peptide sequence, indicating a gene duplication from an ancestral gene. The carboxy terminal half seemed to be unique. Both parts of CHL D are linked with a glutamine/asparagine/proline-rich region flanked by a highly acid-rich segment. Protein-protein interaction among the three subunits CHL D, H and I was studied using the yeast two-hybrid system. Physical interaction was demonstrated between CHL D and CHL I indicating that CHL D is part of the Mg-chelatase. Heterodimer formation of CHL H with CHL I or CHL D could not be demonstrated by transactivation of the lacZ reporter gene. Homodimerization of the CHL D subunit was indicated in the more sensitive assay on X-Gal-containing agar plates. In vitro Mg2+ insertion into protoporphyrin IX was demonstrated in protein extracts of yeast strains expressing

  20. GUN4-Porphyrin Complexes Bind the ChlH/GUN5 Subunit of Mg-Chelatase and Promote Chlorophyll Biosynthesis in Arabidopsis[W

    PubMed Central

    Adhikari, Neil D.; Froehlich, John E.; Strand, Deserah D.; Buck, Stephanie M.; Kramer, David M.; Larkin, Robert M.

    2011-01-01

    The GENOMES UNCOUPLED4 (GUN4) protein stimulates chlorophyll biosynthesis by activating Mg-chelatase, the enzyme that commits protoporphyrin IX to chlorophyll biosynthesis. This stimulation depends on GUN4 binding the ChlH subunit of Mg-chelatase and the porphyrin substrate and product of Mg-chelatase. After binding porphyrins, GUN4 associates more stably with chloroplast membranes and was proposed to promote interactions between ChlH and chloroplast membranes—the site of Mg-chelatase activity. GUN4 was also proposed to attenuate the production of reactive oxygen species (ROS) by binding and shielding light-exposed porphyrins from collisions with O2. To test these proposals, we first engineered Arabidopsis thaliana plants that express only porphyrin binding–deficient forms of GUN4. Using these transgenic plants and particular mutants, we found that the porphyrin binding activity of GUN4 and Mg-chelatase contribute to the accumulation of chlorophyll, GUN4, and Mg-chelatase subunits. Also, we found that the porphyrin binding activity of GUN4 and Mg-chelatase affect the associations of GUN4 and ChlH with chloroplast membranes and have various effects on the expression of ROS-inducible genes. Based on our findings, we conclude that ChlH and GUN4 use distinct mechanisms to associate with chloroplast membranes and that mutant alleles of GUN4 and Mg-chelatase genes cause sensitivity to intense light by a mechanism that is potentially complex. PMID:21467578

  1. The magnesium chelation step in chlorophyll biosynthesis. Annual technical progress report for 1994

    SciTech Connect

    Weinstein, J.

    1994-02-01

    Mg-chelatase catalyses the first step unique to chlorophyll synthesis, namely the insertion of magnesium into protoporphyrin IX. When pea (Pisum sativum L., cv. Spring) chloroplasts are lysed in a buffer lacking magnesium and the thylakoids removed by centrifugation, the remaining mixture of light membranes and soluble proteins (LM/S) has high Mg-chelatase activity. Several lines of evidence are presented to show that the magnesium insertion catalysed by this preparation is a two-step reaction consisting of activation followed by magnesium chelation. An activated state of Mg-chelatase is achieved by preincubating LM/S with ATP. The activated state is observed as the elimination of the approximately 6 min lag in the rate of magnesium chelation upon addition of the prophyrin substrate. The activity of LM/S assayed at low protein concentrations can be greatly enhanced by preincubating at high protein concentrations (12 mg/ml is optimal). This activation effect requires the presence of both LM and S fractions, as well as ATP. Both steps require ATP, but at different concentrations; the first step is optimal at > 0.5 mM (EC{sub 50} = 0.3 mM) and the second step is optimal at 0.3 mM (EC{sub 50} < 0.2 mM). ATP in the first step could be replaced by ATP{gamma}S; this analog could not sustain activity in the second step. This activated state was stable for at least 30 min at room temperature, but chilling of preincubated LM/S on ice for 30 min caused an almost complete loss of the activated state.

  2. Inactivation of Mg chelatase during transition from anaerobic to aerobic growth in Rhodobacter capsulatus.

    PubMed

    Willows, Robert D; Lake, Vanessa; Roberts, Thomas Hugh; Beale, Samuel I

    2003-06-01

    The facultative photosynthetic bacterium Rhodobacter capsulatus can adapt from an anaerobic photosynthetic mode of growth to aerobic heterotrophic metabolism. As this adaptation occurs, the cells must rapidly halt bacteriochlorophyll synthesis to prevent phototoxic tetrapyrroles from accumulating, while still allowing heme synthesis to continue. A likely control point is Mg chelatase, the enzyme that diverts protoporphyrin IX from heme biosynthesis toward the bacteriochlorophyll biosynthetic pathway by inserting Mg(2+) to form Mg-protoporphyrin IX. Mg chelatase is composed of three subunits that are encoded by the bchI, bchD, and bchH genes in R. capsulatus. We report that BchH is the rate-limiting component of Mg chelatase activity in cell extracts. BchH binds protoporphyrin IX, and BchH that has been expressed and purified from Escherichia coli is red in color due to the bound protoporphyrin IX. Recombinant BchH is rapidly inactivated by light in the presence of O(2), and the inactivation results in the formation of a covalent adduct between the protein and the bound protoporphyrin IX. When photosynthetically growing R. capsulatus cells are transferred to aerobic conditions, Mg chelatase is rapidly inactivated, and BchH is the component that is most rapidly inactivated in vivo when cells are exposed to aerobic conditions. The light- and O(2)-stimulated inactivation of BchH could account for the rapid inactivation of Mg chelatase in vivo and provide a mechanism for inhibiting the synthesis of bacteriochlorophyll during adaptation of photosynthetically grown cells to aerobic conditions while still allowing heme synthesis to occur for aerobic respiration.

  3. A Magnesium-Activated Carbon Hybrid Capacitor

    SciTech Connect

    Yoo, HD; Shterenberg, I; Gofer, Y; Doe, RE; Fischer, CC; Ceder, G; Aurbach, D

    2013-12-11

    Prototype cells of hybrid capacitor were developed, comprising activated carbon (AC) cloth and magnesium (Mg) foil as the positive and negative electrodes, respectively. The electrolyte solution included ether solvent (TBF) and a magnesium organo-halo-aluminate complex 0.25 M Mg2Cl3+-Ph2AlCl2-. In this solution Mg can be deposited/dissolved reversibly for thousands of cycles with high reversibility (100% cycling efficiency). The main barrier for integrating porous AC electrodes with this electrolyte solution was the saturation of the pores with the large ions in the AC prior to reaching the potential limit. This is due to the existence of bulky Mg and Al based ionic complexes consisting Cl, alkyl or aryl (R), and THF ligands. This problem was resolved by adding 0.5 M of lithium chloride (LiCl), thus introducing smaller ionic species to the solution. This Mg hybrid capacitor system demonstrated a stable cycle performance for many thousands of cycles with a specific capacitance of 90 Fg(-1) for the AC positive electrodes along a potential range of 2.4 V. (C) 2014 The Electrochemical Society. All rights reserved.

  4. Magnesium Based Materials and their Antimicrobial Activity

    NASA Astrophysics Data System (ADS)

    Robinson, Duane Allan

    The overall goals of this body of work were to characterize the antimicrobial properties of magnesium (Mg) metal and nano-magnesium oxide (nMgO) in vitro, to evaluate the in vitro cytotoxicity of Mg metal, and to incorporate MgO nanoparticles into a polymeric implant coating and evaluate its in vitro antimicrobial properties. In the course of this work it was found that Mg metal, Mg-mesh, and nMgO have in vitro antimicrobial properties that are similar to a bactericidal antibiotic. For Mg metal, the mechanism of this activity appears to be related to an increase in pH (i.e. a more alkaline environment) and not an increase in Mg2+. Given that Mg-mesh is a Mg metal powder, the assumption is that it has the same mechanism of activity as Mg metal. The mechanism of activity for nMgO remains to be elucidated and may be related to a combination of interaction of the nanoparticles with the bacteria and the alkaline pH. It was further demonstrated that supernatants from suspensions of Mg-mesh and nMgO had the same antimicrobial effect as was noted when the particles were used. The supernatant from Mg-mesh and nMgO was also noted to prevent biofilm formation for two Staphylococcus strains. Finally, poly-epsilon-caprolactone (PCL) composites of Mg-mesh (PCL+Mg-mesh) and nMgO (PCL+nMgO) were produced. Coatings applied to screws inhibited growth of Escherichia coli and Pseudomonas aeruginosa and in thin disc format inhibited the growth of Staphylococcus aureus in addition to the E. coli and P. aeruginosa. Pure Mg metal was noted to have some cytotoxic effect on murine fibroblast and osteoblast cell lines, although this effect needs to be characterized further. To address the need for an in vivo model for evaluating implant associated infections, a new closed fracture osteomyelitis model in the femur of the rat was developed. Magnesium, a readily available and inexpensive metal was shown to have antimicrobial properties that appear to be related to its corrosion products and

  5. Structure and organization of a 25 kbp region of the genome of the photosynthetic green sulfur bacterium Chlorobium vibrioforme containing Mg-chelatase encoding genes.

    PubMed

    Petersen, B L; Møller, M G; Stummann, B M; Henningsen, K W

    1998-01-01

    A region comprising approximately 25 kbp of the genome of the strictly anaerobic and obligate photosynthetic green sulfur bacterium Chlorobium vibrioforme has been mapped, subcloned and partly sequenced. Approximately 15 kbp have been sequenced in it's entirety and three genes with significant homology and feature similarity to the bchI, -D and -H genes and the chlI, -D and -H genes of Rhodobacter and Synechocystis strain PCC6803, respectively, which encode magnesium chelatase subunits, have been identified. Magnesium chelatase catalyzes the insertion of Mg2+ into protoporphyrin IX, and is the first enzyme unique to the (bacterio)chlorophyll specific branch of the porphyrin biosynthetic pathway. The organization of the three Mg-chelatase encoding genes is unique to Chlorobium and suggests that the magnesium chelatase of C. vibrioforme is encoded by a single operon. The analyzed 25 kbp region contains five additional open reading frames, two of which display significant homology and feature similarity to genes encoding lipoamide dehydrogenase and genes with function in purine synthesis, and another three display significant homology to open reading frames with unknown function in distantly related bacteria. Putative E. coli sigma 70-like promoter sequences, ribosome binding sequences and rho-independent transcriptional stop signals within the sequenced 15 kbp region are related to the identified genes and orfs. Southern analysis, restriction mapping and partial sequencing of the remaining ca. 10 kbp of the analyzed 25 kbp region have shown that this part includes the hemA, -C, -D and -B genes (MOBERG and AVISSAR 1994), which encode enzymes with function in the early part of the biosynthetic pathway of porphyrins.

  6. Structural genes for Mg-chelatase subunits in barley: Xantha-f, -g and -h.

    PubMed

    Jensen, P E; Willows, R D; Petersen, B L; Vothknecht, U C; Stummann, B M; Kannangara, C G; von Wettstein, D; Henningsen, K W

    1996-03-07

    Barley mutants in the loci Xantha-f, Xantha-g and Xantha-h, when fed with 5-aminolevulinate in the dark, accumulate protoporphyrin IX. Mutant alleles at these loci that are completely blocked in protochlorophyllide synthesis are also blocked in development of prolamellar bodies in etioplasts. In contrast to wild type, the xan-f, -g and -h mutants had no detectable Mg-chelatase activity, whereas they all had methyltransferase activity for synthesis of Mg-protoporphyrin monomethyl ester. Antibodies recognising the CH42 protein of Arabidopsis thaliana and the OLIVE (OLI) protein of Antirrhinum majus immunoreacted in wild-type barley with 42 and 150 kDa proteins, respectively. The xan-h mutants lacked the protein reacting with antibodies raised against the CH42 protein. Two xan-f mutants lacked the 150 kDa protein recognised by the anti-OLI antibody. Barley genes homologous to the A. majus olive and the A. thaliana Ch-42 genes were cloned using PCR and screening of cDNA and genomic libraries. Probes for these genes were applied to Northern blots of RNA from the xantha mutants and confirmed the results of the Western analysis. The mutants xan-f27, -f40, -h56 and -h57 are defective in transcript accumulation while -h38 is defective in translation. Southern blot analysis established that h38 has a deletion of part of the gene. Mutants xan-f10 and -f41 produce both transcript and protein and it is suggested that these mutations are in the catalytic sites of the protein. It is concluded that X an-f -h genes encode two subunits of the barley Mg-chelatase and that X an-g is likely to encode a third subunit. The XAN-F protein displays 82% amino acid sequence identity to the OLI protein of Antirrhinum, 66% to the Synechocystis homologue and 34% identity to the Rhodobacter BchH subunit of Mg-chelatase. The XAN-H protein has 85% amino acid sequence identity to the Arabidopsis CH42 protein, 69% identity to the Euglena CCS protein, 70% identity to the Cryptomonas BchA and

  7. Magnesium Counteracts Vascular Calcification: Passive Interference or Active Modulation?

    PubMed

    Ter Braake, Anique D; Shanahan, Catherine M; de Baaij, Jeroen H F

    2017-08-01

    Over the last decade, an increasing number of studies report a close relationship between serum magnesium concentration and cardiovascular disease risk in the general population. In end-stage renal disease, an association was found between serum magnesium and survival. Hypomagnesemia was identified as a strong predictor for cardiovascular disease in these patients. A substantial body of in vitro and in vivo studies has identified a protective role for magnesium in vascular calcification. However, the precise mechanisms and its contribution to cardiovascular protection remain unclear. There are currently 2 leading hypotheses: first, magnesium may bind phosphate and delay calcium phosphate crystal growth in the circulation, thereby passively interfering with calcium phosphate deposition in the vessel wall. Second, magnesium may regulate vascular smooth muscle cell transdifferentiation toward an osteogenic phenotype by active cellular modulation of factors associated with calcification. Here, the data supporting these major hypotheses are reviewed. The literature supports both a passive inorganic phosphate-buffering role reducing hydroxyapatite formation and an active cell-mediated role, directly targeting vascular smooth muscle transdifferentiation. However, current evidence relies on basic experimental designs that are often insufficient to delineate the underlying mechanisms. The field requires more advanced experimental design, including determination of intracellular magnesium concentrations and the identification of the molecular players that regulate magnesium concentrations in vascular smooth muscle cells. © 2017 American Heart Association, Inc.

  8. Activation of magnesium hydride by pressing with catalytic additives

    NASA Astrophysics Data System (ADS)

    Shikin, I. V.; Elets, D. I.; Voyt, A. P.; Gabis, I. E.

    2017-02-01

    We have studied the activation of magnesium hydride decomposition by means of its pressing with a catalyst. It is established that pressing leads to the formation of metal nuclei, which favor a decrease in the temperature threshold of magnesium hydride decomposition. The introduction of catalytic additives also reduces the temperature of dehydrogenation. The most effective in this respect was found to be the addition of nickel powder.

  9. Mechanism of the Mg-chelatase step in chlorophyll biosynthesis. Final technical report

    SciTech Connect

    Weinstein, Jon

    2002-05-02

    Mg-chelatase catalyzes the insertion of Mg2+ into protoporphyrin-IX (Proto) in the chlorophyll biosynthetic pathway. This is the first step unique to the chlorophyll pathway and is at the branchpoint between heme and chlorophyll biosynthesis. Previous work from our laboratory has shown that the enzyme from pea chloroplasts requires three distinct protein fractions (now known to contain the D, I and H subunits). The reaction requires ATP in two distinct steps: activation requiring two of the fractions (I and D) and metal ion insertion, requiring all three fractions. Work covered in this granting period includes the cloning and expression of the active form of one of the pea subunits and demonstration of the change in chromatographic behavior of the subunits upon activation with ATP.

  10. Regulation of Chloroplast Photosynthetic Activity by Exogenous Magnesium 1

    PubMed Central

    Huber, Steven C.

    1978-01-01

    Magnesium was most inhibitory to photosynthetic reactions by intact chloroplasts when the magnesium was added in the dark before illumination. Two millimolar MgCl2, added in the dark, inhibited CO2-dependent O2 evolution by Hordeum vulgare L. and Spinacia oleracea L. (C3 plants) chloroplasts 70 to 100% and inhibited (pyruvate + oxaloacetate)-dependent O2 evolution by Digitaria sanguinalis L. (C4 plant) mesophyll chloroplasts from 80 to 100%. When Mg2+ was added in the light, O2 evolution was reduced only slightly. O2 evolution in the presence of phosphoglycerate was less sensitive to Mg2+ inhibition than was CO2-dependent O2 evolution. Magnesium prevented the light activation of several photosynthetic enzymes. Two millimolar Mg2+ blocked the light activation of NADP-malate dehydrogenase in D. sanguinalis mesophyll chloroplasts, and the light activation of phosphoribulokinase, NADP-linked glyceraldehyde-3-phosphate dehydrogenase, and fructose 1,6-diphosphatase in barley chloroplasts. The results suggest that Mg2+ inhibits chloroplast photosynthesis by preventing the light activation of certain enzymes. PMID:16660509

  11. Magnesium Modulates Doxorubicin Activity through Drug Lysosomal Sequestration and Trafficking.

    PubMed

    Trapani, Valentina; Luongo, Francesca; Arduini, Daniela; Wolf, Federica I

    2016-03-21

    Magnesium is directly involved in the control of cell growth and survival, but its role in cancer biology and therapy is multifaceted; in particular, it is highly controversial whether magnesium levels can affect therapy outcomes. Here we investigated whether magnesium availability can modulate cellular responses to the widely used chemotherapeutic doxorubicin. We used an in vitro model consisting of mammary epithelial HC11 cells and found that high magnesium availability was correlated with diminished sensitivity both in cells chronically adapted to high magnesium concentrations and in acutely magnesium-supplemented cells. This decrease in sensitivity resulted from reduced intracellular doxorubicin accumulation in the face of a similar drug uptake rate. We observed that high-magnesium conditions caused a decrease in intracellular drug retention by altering drug lysosomal sequestration and trafficking. In our model, magnesium supplementation correspondingly modulated expression of the TRPM7 channel, which is known to control cytoskeletal organization and dynamics and may be involved in the proposed mechanism. Our findings suggest that magnesium supplementation in hypomagnesemic cancer patients may hinder response to therapy.

  12. Magnesium excretion in C. elegans requires the activity of the GTL-2 TRPM channel.

    PubMed

    Teramoto, Takayuki; Sternick, Laura A; Kage-Nakadai, Eriko; Sajjadi, Shirine; Siembida, Jakub; Mitani, Shohei; Iwasaki, Kouichi; Lambie, Eric J

    2010-03-08

    Systemic magnesium homeostasis in mammals is primarily governed by the activities of the TRPM6 and TRPM7 cation channels, which mediate both uptake by the intestinal epithelial cells and reabsorption by the distal convoluted tubule cells in the kidney. In the nematode, C. elegans, intestinal magnesium uptake is dependent on the activities of the TRPM channel proteins, GON-2 and GTL-1. In this paper we provide evidence that another member of the TRPM protein family, GTL-2, acts within the C. elegans excretory cell to mediate the excretion of excess magnesium. Thus, the activity of GTL-2 balances the activities of the paralogous TRPM channel proteins, GON-2 and GTL-1.

  13. Hemin/G-quadruplex structure and activity alteration induced by magnesium cations.

    PubMed

    Kosman, J; Juskowiak, B

    2016-04-01

    The influence of metal cations on G-quadruplex structure and peroxidase-mimicking DNAzyme activity was investigated. Experiments revealed a significant role of magnesium ion, which in the presence of potassium cation influenced DNAzyme activity. This ability has been associated with alteration of G-quadruplex topology and consequently affinity to bind hemin molecule. It has been demonstrated that G-quadruplex based on PS2.M sequence under these conditions formed parallel topology, which exhibited lower activity than that observed in standard potassium-containing solution. On the other hand DNAzyme/magnesium ion system based on telomeric sequence, which did not undergo significant structural changes, exhibited higher peroxidase activity upon magnesium ion addition. In both cases, the stabilization effect of magnesium cations on G-quadruplex structure was observed. The mechanism of DNAzyme activity alteration by magnesium ion can be explained by its influence on the pKa value of DNAzyme. Magnesium ion decreased pKa for PS2.M based system but increased it for telomeric DNAzyme. Magnesium cation effect on G-quadruplex structure as well as DNAzyme activity is particularly important since this ion is one of the most common metal cations in biological samples.

  14. Mechanisms involved in the antiplatelet activity of magnesium in human platelets.

    PubMed

    Sheu, Joen-Rong; Hsiao, George; Shen, Ming-Yi; Fong, Tsorng-Harn; Chen, Yi-Win; Lin, Chien-Huang; Chou, Duen-Suey

    2002-12-01

    In this study, magnesium sulphate dose-dependently (0.6-3.0 mmol/l) inhibited platelet aggregation in human platelets stimulated by agonists. Furthermore, magnesium sulphate (3.0 mmol/l) markedly interfered with the binding of fluorescein isothiocanate-triflavin to the glycoprotein (GP)IIb/IIIa complex in platelets stimulated by collagen. Magnesium sulphate (1.5 and 3.0 mmol/l) also inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. Magnesium sulphate (3.0 mmol/l) significantly inhibited thromboxane A2 formation stimulated by collagen in platelets. Moreover, magnesium sulphate (1.5 and 3.0 mmol/l) obviously increased the fluorescence of platelet membranes tagged with diphenylhexatriene. In addition, magnesium sulphate (1.5 and 3.0 mmol/l) increased the formation of cyclic adenosine monophosphate (AMP) in platelets. Phosphorylation of a protein of Mr 47 000 (P47) was markedly inhibited by magnesium sulphate (1.5 mmol/l). In conclusion, the antiplatelet activity of magnesium sulphate may involve the following two pathways. (1) Magnesium sulphate may initially induce membrane fluidity changes with resulting interference of fibrinogen binding to the GPIIb/IIIa complex, followed by inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca2+ mobilization and phosphorylation of P47. (2) Magnesium sulphate might also trigger the formation of cyclic AM, ultimately resulting in inhibition of the phosphorylation of P47 and intracellular Ca+2 mobilization.

  15. Synthesis, characterization and study of antioxidant activity of quercetin-magnesium complex.

    PubMed

    Ghosh, Nilanjan; Chakraborty, Tania; Mallick, Sougata; Mana, Supriya; Singha, Deepanwita; Ghosh, Balaram; Roy, Souvik

    2015-12-05

    Quercetin (3,3',4',5,7-pentahydroxyflavone) one of the most abundant dietary flavonoids, has been investigated in the presence of magnesium (II) in methanol. The complex formation between quercetin and magnesium (II) was examined under UV-visible, Infra-red and (1)H NMR spectroscopic techniques. The spectroscopic data denoted that quercetin can reacts with magnesium cation (Mg(+2)) through the chelation site in the quercetin molecule. The free radical antioxidant activity of the complex with respect to the parent molecule was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. It was observed that the free radical scavenging activity of quercetin was increased after complexation of magnesium (Mg(+2)) cation.

  16. Identical substitutions in magnesium chelatase paralogs result in chlorophyll deficient soybean mutants

    USDA-ARS?s Scientific Manuscript database

    The soybean (Glycine max (L.) Merr.) chlorophyll deficient line MinnGold is a spontaneous mutant characterized by yellow foliage. Map-based cloning and transgenic complementation revealed that the mutant phenotype is caused by a non-synonymous nucleotide substitution in the third exon of a Mg-chelat...

  17. Magnesium ions increase the activity of Bacillus deramificans pullulanase expressed by Brevibacillus choshinensis.

    PubMed

    Zou, Chun; Duan, Xuguo; Wu, Jing

    2016-08-01

    Addition of MgCl2 to the culture medium has been found to dramatically increase the activity of Bacillus deramificans pullulanase expressed by Brevibacillus choshinensis. The specific activity of the pullulanase obtained from medium supplemented with MgCl2 was also higher than that obtained in culture medium without added magnesium ions. In this work, the mechanism of this increase was studied. When cultured in medium without added magnesium ions, B. choshinensis mainly produced a thermolabile, inactive form of pullulanase. The addition of magnesium ions led to the production of a thermostable, active form of pullulanase. Circular dichroism assays revealed considerable differences in secondary structure between the active and inactive pullulanase forms. Transmission electron microscopy suggested that magnesium ion addition inhibits the shedding of cell wall protein (HWP) layers from the cell surface. Quantitative real-time PCR showed that magnesium ion addition represses transcription of HWP. Because the pullulanase gene and HWP have identical promoters, pullulanase gene transcription was also inhibited. These results suggest that when pullulanase is expressed slowly, it tends to fold into an active form.

  18. Magnesium Excretion in C. elegans Requires the Activity of the GTL-2 TRPM Channel

    PubMed Central

    Teramoto, Takayuki; Sternick, Laura A.; Kage-Nakadai, Eriko; Sajjadi, Shirine; Siembida, Jakub; Mitani, Shohei; Iwasaki, Kouichi; Lambie, Eric J.

    2010-01-01

    Systemic magnesium homeostasis in mammals is primarily governed by the activities of the TRPM6 and TRPM7 cation channels, which mediate both uptake by the intestinal epithelial cells and reabsorption by the distal convoluted tubule cells in the kidney. In the nematode, C. elegans, intestinal magnesium uptake is dependent on the activities of the TRPM channel proteins, GON-2 and GTL-1. In this paper we provide evidence that another member of the TRPM protein family, GTL-2, acts within the C. elegans excretory cell to mediate the excretion of excess magnesium. Thus, the activity of GTL-2 balances the activities of the paralogous TRPM channel proteins, GON-2 and GTL-1. PMID:20221407

  19. An enzyme-coupled continuous spectrophotometric assay for magnesium protoporphyrin IX methyltransferases.

    PubMed

    McLean, Samantha; Hunter, C Neil

    2009-11-15

    The second committed step in chlorophyll biosynthesis is the transfer of a methyl group from S-adenosyl-L-methionine (SAM) to magnesium protoporphyrin IX (MgP) forming MgP monomethylester (MgPME). This reaction is catalyzed by the enzyme MgP methyltransferase (ChlM). Previous investigation of this enzyme has involved the use of time-consuming techniques requiring separation of products from substrates. More recent methyltransferase studies use coupling enzymes to monitor changes in absorption/fluorescence for the measurement of activity. However, due to the spectral properties of porphyrins, many of these assays are unsuitable for analysis of the catalytic properties of ChlM. Here we report the successful development of a coupled, continuous spectrophotometric assay to measure the activity of ChlM. The product of the methyltransferase reaction, S-adenosyl-l-homocysteine (SAH), is converted into adenine and then hypoxanthine by the recombinant coupling enzymes SAH nucleosidase and adenine deaminase, respectively. The appearance of hypoxanthine results in a decrease in absorbance at 265nm. The utility of this assay was shown by the characterization of ChlM from the cyanobacterium Synechocystis sp. PCC 6803. Kinetic parameters obtained support data acquired using the discontinuous HPLC-based assay and provide further evidence for the stimulation of ChlM by the H subunit of magnesium chelatase (ChlH).

  20. Magnesium inhibits Wnt/β-catenin activity and reverses the osteogenic transformation of vascular smooth muscle cells.

    PubMed

    Montes de Oca, Addy; Guerrero, Fatima; Martinez-Moreno, Julio M; Madueño, Juan A; Herencia, Carmen; Peralta, Alan; Almaden, Yolanda; Lopez, Ignacio; Aguilera-Tejero, Escolastico; Gundlach, Kristina; Büchel, Janine; Peter, Mirjam E; Passlick-Deetjen, Jutta; Rodriguez, Mariano; Muñoz-Castañeda, Juan R

    2014-01-01

    Magnesium reduces vascular smooth muscle cell (VSMC) calcification in vitro but the mechanism has not been revealed so far. This work used only slightly increased magnesium levels and aimed at determining: a) whether inhibition of magnesium transport into the cell influences VSMC calcification, b) whether Wnt/β-catenin signaling, a key mediator of osteogenic differentiation, is modified by magnesium and c) whether magnesium can influence already established vascular calcification. Human VSMC incubated with high phosphate (3.3 mM) and moderately elevated magnesium (1.4 mM) significantly reduced VSMC calcification and expression of the osteogenic transcription factors Cbfa-1 and osterix, and up-regulated expression of the natural calcification inhibitors matrix Gla protein (MGP) and osteoprotegerin (OPG). The protective effects of magnesium on calcification and expression of osteogenic markers were no longer observed in VSMC cultured with an inhibitor of cellular magnesium transport (2-aminoethoxy-diphenylborate [2-APB]). High phosphate induced activation of Wnt/β-catenin pathway as demonstrated by the translocation of β-catenin into the nucleus, increased expression of the frizzled-3 gene, and downregulation of Dkk-1 gene, a specific antagonist of the Wnt/β-catenin signaling pathway. The addition of magnesium however inhibited phosphate-induced activation of Wnt/β-catenin signaling pathway. Furthermore, TRPM7 silencing using siRNA resulted in activation of Wnt/β-catenin signaling pathway. Additional experiments were performed to test the ability of magnesium to halt the progression of already established VSMC calcification in vitro. The delayed addition of magnesium decreased calcium content, down-regulated Cbfa-1 and osterix and up-regulated MGP and OPG, when compared with a control group. This effect was not observed when 2-APB was added. In conclusion, magnesium transport through the cell membrane is important to inhibit VSMC calcification in vitro

  1. Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

    USDA-ARS?s Scientific Manuscript database

    The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against E. coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achievin...

  2. Gonadotropin stimulates oocyte translation by increasing magnesium activity through intracellular potassium-magnesium exchange

    SciTech Connect

    Horowitz, S.B.; Tluczek, L.J. )

    1989-12-01

    We previously showed that gonadotropin increases the K{sup +} activity in Xenopus oocytes and that this is a signal for increased translation. However, K{sup +} need not act to control synthesis directly but may act through an unidentified downstream effector. Using microinjection to vary the salt content of oocytes and concomitantly measuring ({sup 3}H)leucine incorporation, we found that small changes in Mg{sup 2+} greatly affect translation rates. (Ca{sup 2+} had little influence.) By measuring intracellular ion activities, we found that oocyte cations existed in a buffer-like (ion-exchange) equilibrium in which K{sup +} and Mg{sup 2+} are the preponderant monovalent and divalent cations. Hence, increasing cellular K{sup +} activity might increase translation by causing Mg{sup 2+} activity to rise. If so, the increased translation rates produced by hormone treatment or K{sup +} injection would be prevented by EDTA, a Mg{sup 2+} chelating agent. This prediction was tested and confirmed. We conclude that, when gonadotropin increases K{sup +} activity, the cell's internal ion-exchange equilibrium is altered thereby increasing Mg{sup 2+} activity and this up-regulates translation.

  3. The magnesium transporter A is activated by cardiolipin and is highly sensitive to free magnesium in vitro.

    PubMed

    Subramani, Saranya; Perdreau-Dahl, Harmonie; Morth, Jens Preben

    2016-01-18

    The magnesium transporter A (MgtA) is a specialized P-type ATPase, believed to import Mg(2+) into the cytoplasm. In Salmonella typhimurium and Escherichia coli, the virulence determining two-component system PhoQ/PhoP regulates the transcription of mgtA gene by sensing Mg(2+) concentrations in the periplasm. However, the factors that affect MgtA function are not known. This study demonstrates, for the first time, that MgtA is highly dependent on anionic phospholipids and in particular, cardiolipin. Colocalization studies confirm that MgtA is found in the cardiolipin lipid domains in the membrane. The head group of cardiolipin plays major role in activation of MgtA suggesting that cardiolipin may act as a Mg(2+) chaperone for MgtA. We further show that MgtA is highly sensitive to free Mg(2+) (Mg(2+)free) levels in the solution. MgtA is activated when the Mg(2+)free concentration is reduced below 10 μM and is strongly inhibited above 1 mM, indicating that Mg(2+)free acts as product inhibitor. Combined, our findings conclude that MgtA may act as a sensor as well as a transporter of Mg(2+).

  4. The magnesium transporter A is activated by cardiolipin and is highly sensitive to free magnesium in vitro

    PubMed Central

    Subramani, Saranya; Perdreau-Dahl, Harmonie; Morth, Jens Preben

    2016-01-01

    The magnesium transporter A (MgtA) is a specialized P-type ATPase, believed to import Mg2+ into the cytoplasm. In Salmonella typhimurium and Escherichia coli, the virulence determining two-component system PhoQ/PhoP regulates the transcription of mgtA gene by sensing Mg2+ concentrations in the periplasm. However, the factors that affect MgtA function are not known. This study demonstrates, for the first time, that MgtA is highly dependent on anionic phospholipids and in particular, cardiolipin. Colocalization studies confirm that MgtA is found in the cardiolipin lipid domains in the membrane. The head group of cardiolipin plays major role in activation of MgtA suggesting that cardiolipin may act as a Mg2+ chaperone for MgtA. We further show that MgtA is highly sensitive to free Mg2+ (Mg2+free) levels in the solution. MgtA is activated when the Mg2+free concentration is reduced below 10 μM and is strongly inhibited above 1 mM, indicating that Mg2+free acts as product inhibitor. Combined, our findings conclude that MgtA may act as a sensor as well as a transporter of Mg2+. DOI: http://dx.doi.org/10.7554/eLife.11407.001 PMID:26780187

  5. Effect of physical activity and age on plasma copper, zinc, iron, and magnesium concentration in physically active healthy males.

    PubMed

    Rakhra, Gurseen; Masih, Daisy; Vats, Annu; Verma, Saroj K; Singh, Vijay K; Rana, Rashmi Tomar; Kirar, Vandana; Singh, Som Nath

    The concentration of nutritionally important minerals in circulation is under tight homeostatic control, however, physical activity and aging influence their body stores and nutritional requirement. The aim of this study was to evaluate the effect of both physical activity and age on plasma concentrations of copper, zinc, iron, and magnesium. Stratified cluster sampling was used for selection of study participants (N = 360) belonging to three physical activity groups: sedentary, moderately active, and highly active on the basis of their physical activity levels as 1.53, 1.8, and 2.3, respectively. They were also divided into six different age groups (18-20, 21-25, 26-30, 31-35, 36-40, and 41-45 y). We assessed nutritional status by determining their body composition using bioelectrical impedance method and measuring intake levels. Fasting blood samples were taken to separate plasma for analysis of copper, zinc, magnesium, and iron. There was a major difference (P < 0.001) in the mean value of plasma copper, zinc, magnesium, and iron for the three activity groups. The plasma copper and iron concentrations were higher in the moderately active group (copper: 1.59 ± 0.05 mg/L, iron: 0.79 ± 0.22 mg/L) whereas zinc concentration was higher in the sedentary group (2.37 ± 0.29 mg/L). Both the highly and moderately active groups had higher plasma magnesium levels compared with the sedentary group. Plasma copper, zinc, magnesium, and iron levels also were influenced by age in a different pattern with respect to physical activity. Physical activity-related energy expenditure and age play a remarkable role in deciphering the plasma mineral levels in the healthy individuals. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Reductive degradation of oxygenated polycyclic aromatic hydrocarbons using an activated magnesium/co-solvent system.

    PubMed

    Elie, Marc R; Clausen, Christian A; Yestrebsky, Cherie L

    2013-05-01

    This study evaluates the capability of zero-valent magnesium and a protic co-solvent to promote the degradation of oxygenated polycyclic aromatic hydrocarbons compounds, specifically 9-fluorenone, 9,10-anthraquinone, 7,12-benz(a)anthraquionone, and 7H-benz(de)anthracene-7-one. At room temperature conditions, greater than 86% degradation efficiency is observed after 24h of reaction time for a mixture containing 0.05 g of magnesium and four selected oxygenated aromatic hydrocarbons with 250 mg L(-1) concentrations. It is noted that glacial acetic acid is needed as an activator for the degradation reaction to proceed. It is also presumed that the acid removes oxide and hydroxide species from the magnesium surface. With the GC-MS analysis of the reaction products, possible reductive pathways are suggested. Furthermore, this study is the first report on the degradation of these emerging contaminants and it is proposed that the magnesium-powder/protic-solvent system is a promising low-cost reagent and may allow for the future development of an economic and environmentally-friendly remediation application. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Effect of changing extracellular levels of magnesium on spontaneous activity and glutamate release in the mouse neocortical slice.

    PubMed Central

    Smith, D. A.; Connick, J. H.; Stone, T. W.

    1989-01-01

    1. The mouse neocortical slice preparation, maintained in a two compartment, grease gap bath, exhibits spontaneous depolarizing activity (with or without rhythmic after potentials) after perfusion with magnesium-free artificial cerebrospinal fluid. 2. If the magnesium concentration is decrementally lowered over an extended time period, then incrementally raised following a similar time course, the spontaneous depolarizing shift activity shows a hysteresis (with regard to both frequency and amplitude), the depolarizing shifts being more resistant to magnesium during the incremental period. 3. The amino acid content of the perfusing fluid was analysed by high performance liquid chromatography (h.p.l.c.). Although a basal efflux of 6 amino acids was quantifiable, only glutamate levels increased following superfusion of the preparation with magnesium-free, artificial cerebrospinal fluid. 4. Glutamate release increased to 266% of the resting release in the presence of magnesium within the first 12 min of the change into magnesium-free artificial cerebrospinal fluid. This increase in release preceded the onset of spontaneous depolarising activity. The release of glutamate remained elevated at 182% of control up to 60 min after perfusion with magnesium-free buffer, when depolarizing activity was well established. 5. A model is presented and discussed for the genesis and maintenance of the spontaneous depolarizing shifts. It is suggested that the maintenance of this spontaneous activity reflects a long term enhancement of neocortical neurone excitability which may be related to long term potentiation in the hippocampus. PMID:2758226

  8. Involvement of the antiplatelet activity of magnesium sulfate in suppression of protein kinase C and the Na+/H+ exchanger.

    PubMed

    Hsiao, George; Shen, Ming-Yi; Chou, Duen-Suey; Lin, Chien-Huang; Chen, Tzeng-Fu; Sheu, Joen-Rong

    2004-01-01

    Magnesium sulfate is widely used to prevent seizures in pregnant women with hypertension. The aim of this study was to examine the inhibitory mechanisms of magnesium sulfate in platelet aggregation in vitro. In this study, magnesium sulfate concentration-dependently (0.6-3.0 mM) inhibited platelet aggregation in human platelets stimulated by agonists. Magnesium sulfate (1.5 and 3.0 mM) also concentration-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by thrombin. Rapid phosphorylation of a platelet protein of M(r) 47,000 (P47), a marker of protein kinase C activation, was triggered by phorbol-12-13-dibutyrate (PDBu, 50 nM). This phosphorylation was markedly inhibited by magnesium sulfate (3.0 mM). Magnesium sulfate (1.5 and 3.0 mM) further inhibited PDBu-stimulated platelet aggregation in human platelets. The thrombin-evoked increase in pHi was markedly inhibited in the presence of magnesium sulfate (3.0 mM). In conclusion, these results indicate that the antiplatelet activity of magnesium sulfate may be involved in the following two pathways: (1) Magnesium sulfate may inhibit the activation of protein kinase C, followed by inhibition of phosphoinositide breakdown and intracellular Ca+2 mobilization, thereby leading to inhibition of the phosphorylation of P47. (2) On the other hand, magnesium sulfate inhibits the Na+/H+ exchanger, leading to reduced intracellular Ca+2 mobilization, and ultimately to inhibition of platelet aggregation and the ATP-release reaction.

  9. Allosteric regulation of SecA: magnesium-mediated control of conformation and activity.

    PubMed

    Gold, Vicki A M; Robson, Alice; Clarke, Anthony R; Collinson, Ian

    2007-06-15

    In bacteria, the SecA protein associates with a ubiquitous protein channel SecYEG where it drives the post-translational secretion of pre-proteins across the plasma membrane. The high-resolution structures of both proteins have been determined in their resting states; however, the mechanism that couples ATP hydrolysis to active transport of substrate proteins through the membrane is not well understood. An analysis of the steady-state ATPase activity of the enzyme reveals that there is an allosteric binding site for magnesium distinct from that associated with hydrolysis of ATP. We have demonstrated that this regulation involves a large conformational change to the SecA dimer, which exerts a strong influence on the turnover and affinity for ATP, as well as the affinity for ADP. The strong inhibitory influence of magnesium on the ATPase activity can be countered by cardiolipin and conditions that promote protein translocation.

  10. Enhancement of antidepressant-like activity by joint administration of imipramine and magnesium in the forced swim test: Behavioral and pharmacokinetic studies in mice.

    PubMed

    Poleszak, Ewa; Wlaź, Piotr; Szewczyk, Bernadeta; Kedzierska, Ewa; Wyska, Elzbieta; Librowski, Tadeusz; Szymura-Oleksiak, Joanna; Fidecka, Sylwia; Pilc, Andrzej; Nowak, Gabriel

    2005-07-01

    The effect of joint administration of imipramine (IMI) and magnesium (Mg) on antidepressant-like activity was studied in mice using forced swim test (FST). Mg doses ineffective per se (5 and 10 mg/kg) given jointly with IMI also at ineffective doses (10 and 15 mg/kg) resulted in a potent reduction in the immobility time. Since these combined treatments did not influence locomotor activity, the antidepressant-like activity was not due to non-specific behavioral activation. Moreover, we estimated the effect of joint administration of magnesium and IMI in FST on serum and brain magnesium, IMI and its active metabolite desipramine (DMI) concentrations in mice. Swim stress (mice subjected to FST) increased the magnesium concentration in serum and decreased it in the brain compared to naive animals. Moreover administration of IMI increased (normalized) magnesium brain concentration, without influence on the serum level. Joint administration of IMI and magnesium did not influence magnesium (compared with FST) or IMI and DMI (compared with IMI treatment alone) concentrations in both examined tissues. The present data demonstrated an enhancement of the antidepressant-like effect by joint administration of IMI and magnesium in the FST, and further indicate the particular role of magnesium in the antidepressant action. Since there was no increase in IMI, DMI or magnesium concentration after joint administration of magnesium and IMI, the data suggest that pharmacodynamic rather than pharmacokinetic interaction between magnesium and IMI is accountable for behavioral effect in the FST.

  11. Propofol and magnesium attenuate isoflurane-induced caspase-3 activation via inhibiting mitochondrial permeability transition pore

    PubMed Central

    2012-01-01

    Background The inhalation anesthetic isoflurane has been shown to open the mitochondrial permeability transition pore (mPTP) and induce caspase activation and apoptosis, which may lead to learning and memory impairment. Cyclosporine A, a blocker of mPTP opening might attenuate the isoflurane-induced mPTP opening, lessening its ripple effects. Magnesium and anesthetic propofol are also mPTP blockers. We therefore set out to determine whether propofol and magnesium can attenuate the isoflurane-induced caspase activation and mPTP opening. Methods We investigated the effects of magnesium sulfate (Mg2+), propofol, and isoflurane on the opening of mPTP and caspase activation in H4 human neuroglioma cells stably transfected to express full-length human amyloid precursor protein (APP) (H4 APP cells) and in six day-old wild-type mice, employing Western blot analysis and flowcytometry. Results Here we show that Mg2+ and propofol attenuated the isoflurane-induced caspase-3 activation in H4-APP cells and mouse brain tissue. Moreover, Mg2+ and propofol, the blockers of mPTP opening, mitigated the isoflurane-induced mPTP opening in the H4-APP cells. Conclusion These data illustrate that Mg2+ and propofol may ameliorate the isoflurane-induced neurotoxicity by inhibiting its mitochondrial dysfunction. Pending further studies, these findings may suggest the use of Mg2+ and propofol in preventing and treating anesthesia neurotoxicity. PMID:22901676

  12. Magnesium Inhibits Wnt/β-Catenin Activity and Reverses the Osteogenic Transformation of Vascular Smooth Muscle Cells

    PubMed Central

    Montes de Oca, Addy; Guerrero, Fatima; Martinez-Moreno, Julio M.; Madueño, Juan A.; Herencia, Carmen; Peralta, Alan; Almaden, Yolanda; Lopez, Ignacio; Aguilera-Tejero, Escolastico; Gundlach, Kristina; Büchel, Janine; Peter, Mirjam E.; Passlick-Deetjen, Jutta; Rodriguez, Mariano; Muñoz-Castañeda, Juan R.

    2014-01-01

    Magnesium reduces vascular smooth muscle cell (VSMC) calcification in vitro but the mechanism has not been revealed so far. This work used only slightly increased magnesium levels and aimed at determining: a) whether inhibition of magnesium transport into the cell influences VSMC calcification, b) whether Wnt/β-catenin signaling, a key mediator of osteogenic differentiation, is modified by magnesium and c) whether magnesium can influence already established vascular calcification. Human VSMC incubated with high phosphate (3.3 mM) and moderately elevated magnesium (1.4 mM) significantly reduced VSMC calcification and expression of the osteogenic transcription factors Cbfa-1 and osterix, and up-regulated expression of the natural calcification inhibitors matrix Gla protein (MGP) and osteoprotegerin (OPG). The protective effects of magnesium on calcification and expression of osteogenic markers were no longer observed in VSMC cultured with an inhibitor of cellular magnesium transport (2-aminoethoxy-diphenylborate [2-APB]). High phosphate induced activation of Wnt/β-catenin pathway as demonstrated by the translocation of β-catenin into the nucleus, increased expression of the frizzled-3 gene, and downregulation of Dkk-1 gene, a specific antagonist of the Wnt/β-catenin signaling pathway. The addition of magnesium however inhibited phosphate-induced activation of Wnt/β-catenin signaling pathway. Furthermore, TRPM7 silencing using siRNA resulted in activation of Wnt/β-catenin signaling pathway. Additional experiments were performed to test the ability of magnesium to halt the progression of already established VSMC calcification in vitro. The delayed addition of magnesium decreased calcium content, down-regulated Cbfa-1 and osterix and up-regulated MGP and OPG, when compared with a control group. This effect was not observed when 2-APB was added. In conclusion, magnesium transport through the cell membrane is important to inhibit VSMC calcification in vitro

  13. Mg-chelatase I subunit 1 and Mg-protoporphyrin IX methyltransferase affect the stomatal aperture in Arabidopsis thaliana.

    PubMed

    Tomiyama, Masakazu; Inoue, Shin-Ichiro; Tsuzuki, Tomo; Soda, Midori; Morimoto, Sayuri; Okigaki, Yukiko; Ohishi, Takaya; Mochizuki, Nobuyoshi; Takahashi, Koji; Kinoshita, Toshinori

    2014-07-01

    To elucidate the molecular mechanisms of stomatal opening and closure, we performed a genetic screen using infrared thermography to isolate stomatal aperture mutants. We identified a mutant designated low temperature with open-stomata 1 (lost1), which exhibited reduced leaf temperature, wider stomatal aperture, and a pale green phenotype. Map-based analysis of the LOST1 locus revealed that the lost1 mutant resulted from a missense mutation in the Mg-chelatase I subunit 1 (CHLI1) gene, which encodes a subunit of the Mg-chelatase complex involved in chlorophyll synthesis. Transformation of the wild-type CHLI1 gene into lost1 complemented all lost1 phenotypes. Stomata in lost1 exhibited a partial ABA-insensitive phenotype similar to that of rtl1, a Mg-chelatase H subunit missense mutant. The Mg-protoporphyrin IX methyltransferase (CHLM) gene encodes a subsequent enzyme in the chlorophyll synthesis pathway. We examined stomatal movement in a CHLM knockdown mutant, chlm, and found that it also exhibited an ABA-insensitive phenotype. However, lost1 and chlm seedlings all showed normal expression of ABA-induced genes, such as RAB18 and RD29B, in response to ABA. These results suggest that the chlorophyll synthesis enzymes, Mg-chelatase complex and CHLM, specifically affect ABA signaling in the control of stomatal aperture and have no effect on ABA-induced gene expression.

  14. Purification and characterization of ferro- and cobalto-chelatases.

    PubMed

    Cánepa, E T; Llambías, E B

    1988-01-01

    Pig liver ferrochelatase was purified 465-fold with about 30% yield, to apparent homogeneity, by a procedure involving solubilization from mitochondria, ammonium sulfate fractionation, and Sephacryl S-300 chromatography. The fraction of each purification step had cobaltochelatase as well as ferrochelatase activity. A purified protein of molecular weight 40,000 was found by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. A molecular weight of approximately 240,000 was obtained by Sephacryl S-300 chromatography. Both activities of the purified fraction increased linearly with time until 2 h, but nonlinear plots were obtained with increasing concentrations of protein. Their optimum pH values were similar. Km values were, for ferrochelatase activity, 23.3 microM for the metal and 30.3 microM for mesoporphyrin, and for cobaltochelatase activity, 27 and 45.5 microM, respectively. Fe2+ and Co2+ each protected against inactivation by heat. Pb2+, Zn2+, Cu2+, or Hg2+ inhibited both activities, while Mn2+ slightly activated; Mg2+ had no effect, at the concentrations tested. There appeared to be an involvement of sulfhydryl groups in metal insertion. Lipids, in correlation with their degree of unsaturation, activated both purified activities; phospholipids also had activation effects. We conclude that a single protein catalyzes the insertion of Fe2+ or Co2+ into mesoporphyrin.

  15. Physiological concentrations of divalent magnesium ion activate the serine/threonine specific protein kinase ERK2.

    PubMed

    Waas, William F; Dalby, Kevin N

    2003-03-18

    Extracellular regulated protein kinase 2 (ERK2) is a eukaryotic protein kinase whose activity is regulated by phorbol esters, serum, and growth factors, and displays enhanced activity in several human tumors. Despite its important biological function, its mechanism of catalysis and mode of regulation are poorly understood. Recently, we showed that in the presence of 10 mM magnesium chloride, ERK2 phosphorylates the transcription factor Ets-1 through a random-ordered ternary-complex mechanism [Waas, W. F., and Dalby, K. N. (2002) J. Biol. Chem. 277, 12532]. Now we provide kinetic evidence that ERK2 must bind two divalent magnesium ions to facilitate catalysis at a physiologically relevant rate, because a second magnesium ion promotes both MgATP2- binding and phosphoryl transfer. The velocity dependence on magnesium at saturating concentrations of the protein substrate, Ets138, over a range of ATP4- and Mg2+ ion concentrations, supports the notion that magnesium is an essential activator of ERK2. At high (> or = 1 mM) concentrations of ATP4-, the velocity dependence on total Mg2+ is sigmoidal, but plateaus at high concentrations of free Mg2+, where the enzyme is fully activated. At concentrations of Mg2+ of < or = 4 mM, the velocity dependence on ATP4- displays a peak when the concentration of ATP4- approaches that of total Mg2+ and tends to zero at high concentrations of ATP4-, where the enzyme is predominantly unactivated. The observed velocity dependencies are consistent with the notion that ERK2*Etsdelta138 complexes and ATP4- compete for the same pool of Mg2+ ions in solution. No binding of ATP4- (0-2.5 mM) by ERK2 (65 microM) can be detected using isothermal titration calorimetry at 27 degrees C, pH 8.0, and an ionic strength of 0.15 M (KCl), suggesting that the complex, MgATP2-, is the true substrate for ERK2. In contrast, 5-iodotubericidin binds ERK2 tightly (K(d) = 1 microM) and displays a competitive inhibition pattern toward MgATP2- and a mixed pattern

  16. Mg chelatase in chlorophyll synthesis and retrograde signaling in Chlamydomonas reinhardtii: CHLI2 cannot substitute for CHLI1

    PubMed Central

    Brzezowski, Pawel; Sharifi, Marina N.; Dent, Rachel M.; Morhard, Marius K.; Niyogi, Krishna K.; Grimm, Bernhard

    2016-01-01

    The oligomeric Mg chelatase (MgCh), consisting of the subunits CHLH, CHLI, and CHLD, is located at the central site of chlorophyll synthesis, but is also thought to have an additional function in regulatory feedback control of the tetrapyrrole biosynthesis pathway and in chloroplast retrograde signaling. In Arabidopsis thaliana and Chlamydomonas reinhardtii, two genes have been proposed to encode the CHLI subunit of MgCh. While the role of CHLI1 in A. thaliana MgCh has been substantially elucidated, different reports provide inconsistent results with regard to the function of CHLI2 in Mg chelation and retrograde signaling. In the present report, the possible functions of both isoforms were analyzed in C. reinhardtii. Knockout of the CHLI1 gene resulted in complete loss of MgCh activity, absence of chlorophyll, acute light sensitivity, and, as a consequence, down-regulation of tetrapyrrole biosynthesis and photosynthesis-associated nuclear genes. These observations indicate a phenotypical resemblance of chli1 to the chlh and chld C. reinhardtii mutants previously reported. The key role of CHLI1 for MgCh reaction in comparison with the second isoform was confirmed by the rescue of chli1 with genomic CHLI1. Because CHLI2 in C. reinhardtii shows lower expression than CHLI1, strains overexpressing CHLI2 were produced in the chli1 background. However, no complementation of the chli1 phenotype was observed. Silencing of CHLI2 in the wild-type background did not result in any changes in the accumulation of tetrapyrrole intermediates or of chlorophyll. The results suggest that, unlike in A. thaliana, changes in CHLI2 content observed in the present studies do not affect formation and activity of MgCh in C. reinhardtii. PMID:26809558

  17. Influence of increased adrenergic activity and magnesium depletion on cardiac rhythm in alcohol withdrawal.

    PubMed Central

    Denison, H; Jern, S; Jagenburg, R; Wendestam, C; Wallerstedt, S

    1994-01-01

    OBJECTIVE--To investigate the prevalence of arrhythmias in alcoholic men during detoxification and its relation to neuroendocrine activation and electrolyte disturbances. DESIGN--Consecutive case-control study. SETTING--Primary and secondary care, detoxification ward. PATIENTS AND CONTROLS--19 otherwise healthy alcoholic men (DSM-III-R) with withdrawal symptoms necessitating detoxification in hospital. 19 age matched, healthy non-alcoholic men as controls for Holter recordings. INTERVENTIONS--Treatment with chlomethiazole; additional treatment with carbamazepine in patients with previous seizures. MAIN OUTCOME MEASURES--Computer based analyses of mean heart rate and arrhythmias from 24 hour Holter recordings, 24 hour urinary excretion of adrenaline and noradrenaline, magnesium retention measured by means of intravenous loading test, and serum concentrations of electrolytes. RESULTS--The 24 hour mean heart rate was higher in the alcoholic men (97.4 beats/minute, 95% confidence interval (CI) 91.2 to 103.6) than in the controls (69.6 beats/minute, 95% CI 65.4 to 73.8, P < 0.001). However, there was no difference in diurnal heart rate variation. The prevalence of premature supraventricular depolarisations was lower in the alcoholic men (P < 0.05). Neither atrial fibrillation nor malignant ventricular arrhythmias occurred. The sinus tachycardia in the alcoholic men correlated with the concomitant urinary excretion of catecholamines (P < 0.05). The mean serum magnesium concentration was 0.78 mmol/l (95% CI 0.73 to 0.83) in the alcoholic men and 0.83 mmol/l (95% CI 0.81 to 0.85) in a reference population of 55 men aged 40. Magnesium depletion (defined as magnesium retention > 30%) was detected in 10 alcoholic men (53%). Three alcoholic men had serum potassium concentrations < or = 3.3 mmol/l on admission. CONCLUSION--Increased adrenergic activity, magnesium depletion, and hypokalaemia are often seen after heavy drinking, but in alcoholic men without clinical heart disease

  18. Thermally activated diffusion of magnesium from bioapatite crystals

    NASA Astrophysics Data System (ADS)

    Danil'Chenko, S. N.; Kulik, A. N.; Pavlenko, P. A.; Kalinichenko, T. G.; Bugai, A. N.; Chemeris, I. I.; Sukhodub, L. F.

    2006-05-01

    We have attempted to use heat treatment followed by ultrasonic treatment to separate the apatite from the non-apatite components of bone mineral in samples from different animals. The Mg content and the Ca/P ratio in the temperature range 560°C-720°C in the samples before and after ultrasonic treatment were determined by electron-probe x-ray microanalysis. Furthermore, we used atomic absorption spectrometry to measure the Mg content in powdered bone samples only after annealing and in distilled water, which was the “sonication” medium. We obtained evidence for thermally activated transition of Mg from a structurally bound state to a labile state at 680°C-720°C. At the same temperature, the Ca-deficient apatite is transformed to stoichiometric apatite. The data presented are evidence that crystals of Ca-deficient bioapatite are surrounded by Ca-enriched surface layers. As a result of thermal transformations at 680°C-720°C, all the Mg in the biomineral is found in the non-apatite environment surrounding the crystals and is removed by ultrasonic treatment, while the surface-localized Ca penetrates into the apatite lattice, restoring its stoichiometry.

  19. Ultrasound-assisted activation of zero-valent magnesium for nitrate denitrification: identification of reaction by-products and pathways.

    PubMed

    Ileri, Burcu; Ayyildiz, Onder; Apaydin, Omer

    2015-07-15

    Zero-valent magnesium (Mg(0)) was activated by ultrasound (US) in an aim to promote its potential use in water treatment without pH control. In this context, nitrate reduction was studied at batch conditions using various doses of magnesium powder and ultrasound power. While neither ultrasound nor zero-valent magnesium alone was effective for reducing nitrate in water, their combination removed up to 90% of 50 mg/L NO3-N within 60 min. The rate of nitrate reduction by US/Mg(0) enhanced with increasing ultrasonic power and magnesium dose. Nitrogen gas (N2) and nitrite (NO2(-)) were detected as the major reduction by-products, while magnesium hydroxide Mg(OH)2 and hydroxide ions (OH(-)) were identified as the main oxidation products. The results from SEM-EDS measurements revealed that the surface oxide level decreased significantly when the samples of Mg(0) particles were exposed to ultrasonic treatment. The surface passivation of magnesium particles was successfully minimized by mechanical forces of ultrasound, which in turn paved the way to sustain the catalyst activity toward nitrate reduction.

  20. Effect of Surface-active Additives on Physical Properties of Slurries of Vapor-process Magnesium

    NASA Technical Reports Server (NTRS)

    Pinns, Murray L

    1955-01-01

    The presence of 3 to 5 percent surface-active additive gave the lowest Brookfield apparent viscosity, plastic viscosity, and yield value that were obtained for slurry fuels containing approximately 50 percent vapor-process magnesium in JP-1 fuel. The slurries settled little and were easily remixed. A polyoxyethylene dodecyl alcohol was the most effective of 13 additives tested in reducing the Brookfield apparent viscosity and the yield value of the slurry. The seven most effective additives all had a hydroxyl group plus an ester or polyoxethylene group in the molecule. The densities of some of the slurries were measured.

  1. Magnesium as Novel Material for Active Plasmonics in the Visible Wavelength Range.

    PubMed

    Sterl, Florian; Strohfeldt, Nikolai; Walter, Ramon; Griessen, Ronald; Tittl, Andreas; Giessen, Harald

    2015-12-09

    Investigating new materials plays an important role for advancing the field of nanoplasmonics. In this work, we fabricate nanodisks from magnesium and demonstrate tuning of their plasmon resonance throughout the whole visible wavelength range by changing the disk diameter. Furthermore, we employ a catalytic palladium cap layer to transform the metallic Mg particles into dielectric MgH2 particles when exposed to hydrogen gas. We prove that this transition can be reversed in the presence of oxygen. This yields plasmonic nanostructures with an extinction spectrum that can be repeatedly switched on or off or kept at any intermediate state, offering new perspectives for active plasmonic metamaterials.

  2. A new activator strontium for magnesium tetraborate: PL and TL studies.

    PubMed

    Evis, D; Yucel, A; Kizilkaya, N; Depci, T; Kafadar, V E; Öztürk, E; Yildirim, R G

    2016-10-01

    Strontium was used for the first time as an activator agent for magnesium tetraborate (MBO) and photoluminescence (PL) and thermoluminescence (TL) properties were determined using a spectrophotometer and a TL reader, respectively. The results proved that 0.25wt% Sr ratio played an important role in prolonging the afterglow and the phosphor gave the main TL peak with the highest intensity at 200°C like an ideal case. Therefore, it is worthwhile to carry out continuous and systematic research on it. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Influence of the phosphodiesterase type 5 inhibitor, sildenafil, on antidepressant-like activity of magnesium in the forced swim test in mice.

    PubMed

    Socała, Katarzyna; Nieoczym, Dorota; Poleszak, Ewa; Wlaź, Piotr

    2012-01-01

    Magnesium, which acts as an antagonist of N-methyl-D-aspartate (NMDA) subtype of glutamate receptors, exerts antidepressant-like activity in animal models of depression. The present study was undertaken to elucidate the influence of sildenafil, a phosphodiesterase type 5 inhibitor, on the anti-immobility action of magnesium in the forced swim test in mice. Swim sessions were conducted by placing mice in glass cylinders filled with water for 6 min and the duration of the behavioral immobility during the last 4 min of the test was evaluated. Locomotor activity was measured with photoresistor actimeters. Serum and brain magnesium levels were assayed spectrophotometrically. Magnesium at a dose of 30 mg/kg, i.p. significantly decreased the immobility time while sildenafil (5, 10 and 20 mg/kg, i.p.) in a dose-dependent manner reduced the antidepressant-like activity of magnesium. The co-administration of magnesium with sildenafil at the highest dose entirely abolished the antidepressant-like effect of magnesium and caused a statistically significant increase in immobility duration as compared to the control group. Combination of magnesium with sildenafil resulted in a potent reduction (80%) of locomotor activity and pharmacokinetic studies showed a significant increase of magnesium concentration in serum (as compared to magnesium treatment alone) without changes within brain tissue in mice treated with magnesium and sildenafil. When given alone, sildenafil caused a significant increase in magnesium levels in both serum and brain. Our results indicate that a simultaneous treatment with magnesium and sildenafil results in hypermagnesemia in laboratory animals. However, the mechanism underlying this effect remains elusive.

  4. Mutation of Gly195 of the ChlH Subunit of Mg-chelatase Reduces Chlorophyll and Further Disrupts PS II Assembly in a Ycf48-Deficient Strain of Synechocystis sp. PCC 6803

    PubMed Central

    Crawford, Tim S.; Eaton-Rye, Julian J.; Summerfield, Tina C.

    2016-01-01

    Biogenesis of the photosystems in oxygenic phototrophs requires co-translational insertion of chlorophyll a. The first committed step of chlorophyll a biosynthesis is the insertion of a Mg2+ ion into the tetrapyrrole intermediate protoporphyrin IX, catalyzed by Mg-chelatase. We have identified a Synechocystis sp. PCC 6803 strain with a spontaneous mutation in chlH that results in a Gly195 to Glu substitution in a conserved region of the catalytic subunit of Mg-chelatase. Mutant strains containing the ChlH Gly195 to Glu mutation were generated using a two-step protocol that introduced the chlH gene into a putative neutral site in the chromosome prior to deletion of the native gene. The Gly195 to Glu mutation resulted in strains with decreased chlorophyll a. Deletion of the PS II assembly factor Ycf48 in a strain carrying the ChlH Gly195 to Glu mutation did not grow photoautotrophically. In addition, the ChlH-G195E:ΔYcf48 strain showed impaired PS II activity and decreased assembly of PS II centers in comparison to a ΔYcf48 strain. We suggest decreased chlorophyll in the ChlH-G195E mutant provides a background to screen for the role of assembly factors that are not essential under optimal growth conditions. PMID:27489555

  5. Biological activity evaluation of magnesium fluoride coated Mg-Zn-Zr alloy in vivo.

    PubMed

    Jiang, Hongfeng; Wang, Jingbo; Chen, Minfang; Liu, Debao

    2017-06-01

    To explore the biodegradable characteristics and biological properties, which could promote new bone formation, of MgF2 coated magnesium alloy (Mg-3wt%Zn-0.5wt%Zr) in rabbits. Magnesium alloy with MgF2 coating was made and the MgF2/Mg-Zn-Zr was implanted in the femoral condyle of rabbits. Twelve healthy adult Japanese white rabbits in weight of 2.8-3.2kg were averagely divided into A(Mg-Zn-Zr) group and B(MgF2/MgZn-Zr) group. Indexes such as microstructural evolution, SEM scan, X-ray, Micro-CT and mechanical properties were observed and detected at 1th day, 2th, 4th, 8th, 12th, 24th week after implantation. Low-density regions occurred around the cancellous bone, and the regions gradually expanded during the 12weeks after implantation. The implant was gradually absorbed from 12 to 24weeks. The density of surrounding cancellous bone increased compared with the 12th week data. The degradation rate of B group was lower than that of A group (P<0.01), while the density of the surrounding cancellous bone increased more evenly. In B group, SEM images after 12weeks showed the rich bone tissues on the alloy surface that were attached by active fibers. Micro-CT also presented alloy residue potholes on the surfaces of alloy combinated with bone tissues. Additionally, the trabecular bone had relatively integrated structures with surrounding cavities. MgF2 can effectively decrease the degradation rate of Mg-Zn-Zr in vivo. Mg-Zn-Zr coated with MgF2 can effectively inhibit the corrosion, and delay the release of magnesium ions. The biological properties of the coating itself presented good biocompatibility and bioactivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Effect of magnesium cations on the activity and stability of β-galactosidases

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Pilipenko, O. S.; Poltorak, O. M.; Chukhrai, E. S.

    2007-07-01

    It was shown that the presence of magnesium cations in the reaction mixture increases, approximately twofold, the activity of bacterial Escherichia coli and yeast Kluyveromyces lactis β-galactosidases but does not affect the activity of bovine liver and fungous Penicillium canescens β-galactosidases. The catalytic constants for E. coli and yeast K. lactis β-galactosidases in the presence of 0.01 M and in the absence of Mg2+ cations were determined (490 and 220 s-1 and 59.8 and 37.4 s-1, respectively). It was shown that the Michaelis constants for these two enzymes are higher in the presence of Mg2+ cations, that the thermal stability of E. coli and K. Lactis β-galactosidases is higher in the presence of 0.01 M Mg2+, and that the effective rate constants of thermal inactivation of the enzymes are two-to eightfold lower, depending on conditions, in the presence of Mg2+ cations. The maximum stabilizing effect of magnesium cations was observed at weak alkaline pH values (7.5-8.5).

  7. Controlling the corrosion and cathodic activation of magnesium via microalloying additions of Ge.

    PubMed

    Liu, R L; Hurley, M F; Kvryan, A; Williams, G; Scully, J R; Birbilis, N

    2016-06-28

    The evolution of corrosion morphology and kinetics for magnesium (Mg) have been demonstrated to be influenced by cathodic activation, which implies that the rate of the cathodic partial reaction is enhanced as a result of anodic dissolution. This phenomenon was recently demonstrated to be moderated by the use of arsenic (As) alloying as a poison for the cathodic reaction, leading to significantly improved corrosion resistance. The pursuit of alternatives to toxic As is important as a means to imparting a technologically safe and effective corrosion control method for Mg (and its alloys). In this work, Mg was microalloyed with germanium (Ge), with the aim of improving corrosion resistance by retarding cathodic activation. Based on a combined analysis herein, we report that Ge is potent in supressing the cathodic hydrogen evolution reaction (reduction of water) upon Mg, improving corrosion resistance. With the addition of Ge, cathodic activation of Mg subject to cyclic polarisation was also hindered, with beneficial implications for future Mg electrodes.

  8. Controlling the corrosion and cathodic activation of magnesium via microalloying additions of Ge

    NASA Astrophysics Data System (ADS)

    Liu, R. L.; Hurley, M. F.; Kvryan, A.; Williams, G.; Scully, J. R.; Birbilis, N.

    2016-06-01

    The evolution of corrosion morphology and kinetics for magnesium (Mg) have been demonstrated to be influenced by cathodic activation, which implies that the rate of the cathodic partial reaction is enhanced as a result of anodic dissolution. This phenomenon was recently demonstrated to be moderated by the use of arsenic (As) alloying as a poison for the cathodic reaction, leading to significantly improved corrosion resistance. The pursuit of alternatives to toxic As is important as a means to imparting a technologically safe and effective corrosion control method for Mg (and its alloys). In this work, Mg was microalloyed with germanium (Ge), with the aim of improving corrosion resistance by retarding cathodic activation. Based on a combined analysis herein, we report that Ge is potent in supressing the cathodic hydrogen evolution reaction (reduction of water) upon Mg, improving corrosion resistance. With the addition of Ge, cathodic activation of Mg subject to cyclic polarisation was also hindered, with beneficial implications for future Mg electrodes.

  9. Magnesium basics

    PubMed Central

    Ketteler, Markus

    2012-01-01

    As a cofactor in numerous enzymatic reactions, magnesium fulfils various intracellular physiological functions. Thus, imbalance in magnesium status—primarily hypomagnesaemia as it is seen more often than hypermagnesaemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Measuring total serum magnesium is a feasible and affordable way to monitor changes in magnesium status, although it does not necessarily reflect total body magnesium content. The following review focuses on the natural occurrence of magnesium and its physiological function. The absorption and excretion of magnesium as well as hypo- and hypermagnesaemia will be addressed. PMID:26069819

  10. Exogenous Magnesium Chloride Reduces the Activated Partial Thromboplastin Times of Lupus Anticoagulant-Positive Patients

    PubMed Central

    Tokutake, Takayoshi; Baba, Hisami; Shimada, Yuji; Takeda, Wataru; Sato, Keijiro; Hiroshima, Yuki; Kirihara, Takehiko; Shimizu, Ikuo; Nakazawa, Hideyuki; Kobayashi, Hikaru; Ishida, Fumihiro

    2016-01-01

    The activated partial thromboplastin time (APTT) assay is a basic hemostatic assay based on the time it takes for clots to form in plasma samples after the addition of calcium chloride. It is used to screen for various coagulation disorders. Several previous reports have suggested that magnesium (Mg) might contribute to coagulation reactions by binding to specific coagulation proteins. We investigated the effects of Mg on the APTT. In healthy controls, the APTT was significantly prolonged in proportion to the increase in the concentration of magnesium chloride in the range from 2.1 to 16.7 mmol/L. Among eight samples from patients with various disorders that exhibited prolonged APTT, two samples demonstrated shorter APTT when Mg was added, both of which were from patients that were positive for lupus anticoagulant. When we examined 206 clinical APTT samples, we found that Mg shortened the APTT of two samples. These two samples were also from lupus anticoagulant-positive patients (p-value: <0.003). Our findings regarding the unique effects of exogenous Mg on the APTT of lupus anticoagulant-positive patients might shed light on the role of Mg in APTT assays and lead to the development of a novel screening method for lupus anticoagulant. PMID:27355205

  11. Magnesium sulfate treatment against sarin poisoning: dissociation between overt convulsions and recorded cortical seizure activity.

    PubMed

    Katalan, Shahaf; Lazar, Shlomi; Brandeis, Rachel; Rabinovitz, Ishai; Egoz, Inbal; Grauer, Ettie; Bloch-Shilderman, Eugenia; Raveh, Lily

    2013-02-01

    Sarin, a potent organophosphate cholinesterase inhibitor, induces an array of toxic effects including convulsions. Many antidotal treatments contain anticonvulsants to block seizure activity and the ensuing brain damage. Magnesium sulfate (MGS) is used to suppress eclamptic seizures in pregnant women with hypertension and was shown to block kainate-induced convulsions. Magnesium sulfate was evaluated herein as an anticonvulsant against sarin poisoning and its efficacy was compared with the potent anticonvulsants midazolam (MDZ) and caramiphen (CRM). Rats were exposed to a convulsant dose of sarin (96 μg/kg, im) and 1 min later treated with the oxime TMB4 and atropine to increase survival. Five minutes after initiation of convulsions, MGS, CRM, or MDZ were administered. Attenuation of tonic-clonic convulsions was observed following all these treatments. However, radio-telemetric electro-corticography (ECoG) monitoring demonstrated sustained seizure activity in MGS-injected animals while this activity was completely blocked by MDZ and CRM. This disrupted brain activity was associated with marked increase in brain translocator protein levels, a marker for brain damage, measured 1 week following exposure. Additionally, histopathological analyses of MGS-treated group showed typical sarin-induced brain injury excluding the hippocampus that was partially protected. Our results clearly show that MGS demonstrated misleading features as an anticonvulsant against sarin-induced seizures. This stems from the dissociation observed between overt convulsions and seizure activity. Thus, the presence or absence of motor convulsions may be an unreliable indicator in the assessment of clinical status and in directing adequate antidotal treatments following exposure to nerve agents in battle field or terror attacks.

  12. Magnesium sulfate provides neuroprotection in lipopolysaccharide-activated primary microglia by inhibiting NF-κB pathway.

    PubMed

    Gao, Feng; Ding, Baozhong; Zhou, Longan; Gao, Xueshan; Guo, Huiguang; Xu, Hong

    2013-10-01

    Magnesium sulfate has been used as an anticonvulsant in severe preeclamptic or eclamptic women prior to surgical trauma, but its effects on neuroinflammation is not well defined. In the present study, we investigated the neuroprotective effects of magnesium sulfate in lipopolysaccharide (LPS)-induced microglia and explored the underlying mechanism. Microglia was incubated with LPS in the presence or absence of various concentrations of magnesium sulfate, or L-type calcium channel activator BAY-K8644. The levels of inflammatory mediators, such as nitric oxide, prostaglandin E2, interleukin 1β, and tumor necrosis factor α, were measured using enzyme-linked immunosorbent assay. The expression of inducible nitric oxide synthase mRNA was detected by reverse-transcription polymerase chain reaction. Nuclear factor κB (NF-κB) activity in the nuclear extract of microglia was detected by NF-κB p50/p65 transcription factor assay kit. Magnesium sulfate at 5 and 10 mmol/L significantly inhibited the release of nitric oxide, prostaglandin E2, interleukin 1β, and tumor necrosis factor α, and the expression of inducible nitric oxide synthase mRNA in LPS-activated microglia. Furthermore, magnesium sulfate inhibited the translocation of NF-κB from the cytoplasm to the nucleus in a dose-dependent manner. Notably, these effects were significantly reversed by L-type calcium channel activator BAY-K8644. Magnesium sulfate protects microglia against LPS-induced release of inflammatory mediators, and these effects may be mediated by inhibiting L-type calcium channels and NF-κB signaling. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  13. Correlation of magnesium intake with metabolic parameters, depression and physical activity in elderly type 2 diabetes patients: a cross-sectional study

    PubMed Central

    2012-01-01

    Background Type 2 diabetes mellitus is a major global public health problem in the worldwide and is increasing in aging populations. Magnesium intake may be one of the most important factors for diabetes prevention and management. Low magnesium intake may exacerbate metabolic abnormalities. In this study, the relationships of magnesium intake with metabolic parameters, depression and physical activity in elderly patients with type 2 diabetes were investigated. Methods This cross-sectional study involved 210 type 2 diabetes patients aged 65 years and above. Participants were interviewed to obtain information on lifestyle and 24-hour dietary recall. Assessment of depression was based on DSM-IV criteria. Clinical variables measured included anthropometric measurements, blood pressure, and biochemical determinations of blood and urine samples. Linear regression was applied to determine the relationships of magnesium intake with nutritional variables and metabolic parameters. Results Among all patients, 88.6% had magnesium intake which was less than the dietary reference intake, and 37.1% had hypomagnesaemia. Metabolic syndromes and depression were associated with lower magnesium intake (p < 0.05). A positive relationship was found between magnesium intake and HDL-cholesterol (p = 0.005). Magnesium intake was inversely correlated with triglyceride, waist circumference, body fat percent and body mass index (p < 0.005). After controlling confounding factor, HDL-cholesterol was significantly higher with increasing quartile of magnesium intake (p for trend = 0005). Waist circumference, body fat percentage, and body mass index were significantly lower with increase quartile of magnesium intake (p for trend < 0.001). The odds of depression, central obesity, high body fat percentage, and high body mass index were significantly lower with increasing quartile of magnesium intake (p for trend < 0.05). In addition, magnesium intake was related to high

  14. Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag.

    PubMed

    Chartier, D; Muzeau, B; Stefan, L; Sanchez-Canet, J; Monguillon, C

    2017-03-15

    Magnesium alloys and graphite from spent nuclear fuel have been stored together in La Hague plant. The packaging of these wastes is under consideration. These wastes could be mixed in a grout composed of industrially available cement (Portland, calcium aluminate…). Within the alkaline pore solution of these matrixes, magnesium alloys are imperfectly protected by a layer of Brucite resulting in a slow corrosion releasing hydrogen. As the production of this gas must be considered for the storage safety, and the quality of wasteform, it is important to select a cement matrix capable of lowering the corrosion kinetics. Many types of calcium based cements have been tested and most of them have caused strong hydrogen production when magnesium alloys and graphite are conditioned together because of galvanic corrosion. Exceptions are binders based on alkali hydroxide activated ground granulated blast furnace slag (BFS) which are presented in this article.

  15. Magnesium deficiency promotes a pro-atherogenic phenotype in cultured human endothelial cells via activation of NFkB.

    PubMed

    Ferrè, Silvia; Baldoli, Erika; Leidi, Marzia; Maier, Jeanette A M

    2010-11-01

    Phenotypic modulation of endothelium to a dysfunctional state contributes to the pathogenesis of atherosclerosis, partly through the activation of the transcription factor NFkB. Several data indicate that magnesium deficiency caused by prolonged insufficient intake and/or defects in its homeostasis may be a missing link between diverse cardiovascular risk factors and atherosclerosis. Here we report that endothelial cells cultured in low magnesium rapidly activate NFkB, an event which is prevented by exposure to the anti-oxidant trolox. It is well known that NFkB activation correlates with marked alterations of the cytokine network. In the present study, we show that exposure of endothelial cells to low magnesium increases the secretion of RANTES, interleukin 8 and platelet derived growth factor BB, all important players in atherogenesis. Moreover, we describe the increased secretion of matrix metalloprotease-2 and -9 and of their inhibitor TIMP-2. Interestingly, by zymography we show that metalloprotease activity predominated over the inhibitory effect of TIMP-2. These results indicate that low magnesium promotes endothelial dysfunction by inducing pro-inflammatory and pro-atherogenic events. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Effect of magnesium ions on the activity of the cytosolic NADH/cytochrome c electron transport system.

    PubMed

    La Piana, Gianluigi; Gorgoglione, Vincenza; Laraspata, Daniela; Marzulli, Domenico; Lofrumento, Nicola E

    2008-12-01

    Cytochrome c (cyto-c), added to isolated mitochondria, activates the oxidation of extramitochondrial NADH and the generation of a membrane potential, both linked to the activity of the cytosolic NADH/cyto-c electron transport pathway. The data presented in this article show that the protective effect of magnesium ions on the permeability of the mitochondrial outer membrane, supported by previously published data, correlates with the finding that, in hypotonic but not isotonic medium, magnesium promotes a differential effect on both the additional release of endogenous cyto-c and on the increased rate of NADH oxidation, depending on whether it is added before or after the mitochondria. At the same time, magnesium prevents or almost completely removes the binding of exogenously added cyto-c. We suggest that, in physiological low-amplitude swelling, magnesium ions may have the function, together with other factors, of modulating the amount of cyto-c molecules transferred from the mitochondrial intermembrane space into the cytosol, required for the correct execution of the apoptotic programme and/or the activation of the NADH/cyto-c electron transport pathway.

  17. Convenient method of simultaneously analyzing aluminum and magnesium in pharmaceutical dosage forms using californium-252 thermal neutron activation.

    PubMed

    Landolt, R R; Hem, S L

    1983-05-01

    A commercial antacid suspension containing aluminum hydroxide and magnesium hydroxide products was used as a model sample to study the use of a californium-252 thermal neutron activation as a method for quantifying aluminum content as well as for the simultaneous assay of aluminum and magnesium. A 3.5-micrograms californium-252 source was used for the activation, and the induced aluminum-28 and magnesium-27 activity was simultaneously measured by sodium iodide crystal gamma-ray spectrometry using dual single-channel analyzers and scalers. The antacid suspension was contained in a chamber designed with the unique capability of serving as the container for counting the induced radioactivity in addition to being the irradiation chamber itself. Ten replicate irradiations were performed, and the precision was compared with 10 replicate analyses of the antacid suspension using the official ethylenediaminetetraacetic acid titration method. For aluminum the precision was 1.4 versus 0.62% for the titration method. For the magnesium the precision was 5.3 versus 0.79% for the titration method. This pilot study demonstrated that use of more intense californium-252 sources, which are commonly available, would provide a method that is competitive with the ethylenediaminetetraacetic acid titration method in precision and in other aspects as well.

  18. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H.

    1998-12-31

    This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

  19. Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

    NASA Astrophysics Data System (ADS)

    Jin, Tony; He, Yiping

    2011-12-01

    The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against Escherichia coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achieving more than 7 log reductions in bacterial counts. The antibacterial activity of MgO NP increased as the concentrations of MgO increased. A synergistic effect of MgO in combination with nisin was observed as well. However, the addition of ZnO NP to MgO NP did not enhance the antibacterial activity of MgO against both pathogens. Scanning electron microscopy was used to characterize the morphological changes of E. coli O157:H7 before and after antimicrobial treatments. It was revealed that MgO NP treatments distort and damage the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. These results suggest that MgO NP alone or in combination with nisin could potentially be used as an effective antibacterial agent to enhance food safety.

  20. Controlling the corrosion and cathodic activation of magnesium via microalloying additions of Ge

    PubMed Central

    Liu, R. L.; Hurley, M. F.; Kvryan, A.; Williams, G.; Scully, J. R.; Birbilis, N.

    2016-01-01

    The evolution of corrosion morphology and kinetics for magnesium (Mg) have been demonstrated to be influenced by cathodic activation, which implies that the rate of the cathodic partial reaction is enhanced as a result of anodic dissolution. This phenomenon was recently demonstrated to be moderated by the use of arsenic (As) alloying as a poison for the cathodic reaction, leading to significantly improved corrosion resistance. The pursuit of alternatives to toxic As is important as a means to imparting a technologically safe and effective corrosion control method for Mg (and its alloys). In this work, Mg was microalloyed with germanium (Ge), with the aim of improving corrosion resistance by retarding cathodic activation. Based on a combined analysis herein, we report that Ge is potent in supressing the cathodic hydrogen evolution reaction (reduction of water) upon Mg, improving corrosion resistance. With the addition of Ge, cathodic activation of Mg subject to cyclic polarisation was also hindered, with beneficial implications for future Mg electrodes. PMID:27350286

  1. Effect of Food Thickener on Dissolution and Laxative Activity of Magnesium Oxide Tablets in Mice.

    PubMed

    Tomita, Takashi; Goto, Hidekazu; Yoshimura, Yuya; Kato, Kazushige; Yoshida, Tadashi; Tanaka, Katsuya; Sumiya, Kenji; Kohda, Yukinao

    2016-01-01

    The present study examined the dissolution of magnesium oxide (MgO) from MgO tablets placed in a food thickening agent (food thickener) and its effects on laxative activity. We prepared mixtures of MgO tablets suspended in an aqueous suspension and food thickeners in order to evaluate the dissolution of MgO. The results of the dissolution tests revealed that agar-based food thickeners did not affect the MgO dissolution. In contrast, some xanthan gum-based food-thickener products show dissolution rates with certain mixtures containing disintegrated MgO tablets suspended in a food thickener that decrease over time. However, other xanthan gum-based food-thickener products show dissolution rates that decrease immediately after mixing, regardless of the time they were allowed to stand. In order to investigate the laxative activity of MgO, we orally administered a mixture of MgO suspension and food thickener to mice and observed their bowel movements. The animal experiments showed that when agar-based food thickeners were used, the laxative activity of MgO was not affected, but it decreased when xanthan gum-based food thickeners were used.

  2. The Surface Modification and Antimicrobial Activity of Basic Magnesium Hypochlorite Nanoparticles.

    PubMed

    Xu, Lijian; Tang, Zengmin; Xu, Jianxiong; Zhang, Jide; Du, Jingjing; Li, Na

    2015-02-01

    The basic magnesium hypochlorite (BMH) nanoparticles were prepared by two micro-emulsion techniques and modified with sodium stearate. The influences of the main technical parameters such as the addition amount of sodium stearate, reaction temperature and reaction time on the Lipophilic degree (LD) of the modified BMH nanoparticles were investigated. The characteristics of the BMH nanoparticles were analysed by means of Malvern Instruments, transmission electron microscopy (TEM), water contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). The antimicrobial activity of the modified BMH nanoparticles was investigated with the antibacterial circle test. The results showed that the average size of the BMH nanoparticles was 305 nm. The BMH nanoparticles had been successfully modified by sodium stearate and the LD of.the modified BMH nanoparticles was 8.4% when the addition amount of sodium stearate was 0.15 g, the reaction temperature was 10 °C and the reaction time was 5 h. The dispersibility and hydrophobicity of the modified BMH nanoparticles were improved and the contact angle was up to 103 °, the modified BMH nanoparticles still had excellent antimicrobial activity after modification.

  3. Magnesium sulfate reduces EEG activity but is not neuroprotective after asphyxia in preterm fetal sheep.

    PubMed

    Galinsky, Robert; Draghi, Vittoria; Wassink, Guido; Davidson, Joanne O; Drury, Paul P; Lear, Christopher A; Gunn, Alistair J; Bennet, Laura

    2017-04-01

    Magnesium sulfate is now widely recommended for neuroprotection for preterm birth; however, this has been controversial because there is little evidence that magnesium sulfate is neuroprotective. Preterm fetal sheep (104 days gestation; term is 147 days) were randomly assigned to receive sham occlusion (n = 7), i.v. magnesium sulfate (n = 10) or saline (n = 8) starting 24 h before asphyxia until 24 h after asphyxia. Sheep were killed 72 h after asphyxia. Magnesium sulfate infusion reduced electroencephalograph power and fetal movements before asphyxia. Magnesium sulfate infusion did not affect electroencephalograph power during recovery, but was associated with marked reduction of the post-asphyxial seizure burden (mean ± SD: 34 ± 18 min vs. 107 ± 74 min, P < 0.05). Magnesium sulfate infusion did not affect subcortical neuronal loss. In the intragyral and periventricular white matter, magnesium sulfate was associated with reduced numbers of all (Olig-2+ve) oligodendrocytes in the intragyral (125 ± 23 vs. 163 ± 38 cells/field) and periventricular white matter (162 ± 39 vs. 209 ± 44 cells/field) compared to saline-treated controls ( P < 0.05), but no effect on microglial induction or astrogliosis. In conclusion, a clinically comparable dose of magnesium sulfate showed significant anticonvulsant effects after asphyxia in preterm fetal sheep, but did not reduce asphyxia-induced brain injury and exacerbated loss of oligodendrocytes.

  4. Inhibition of beta-amylase activity by calcium, magnesium and zinc ions determined by spectrophotometry and isothermal titration calorimetry.

    PubMed

    Dahot, M Umar; Saboury, A A; Moosavi-Movahedi, A A

    2004-04-01

    The inhibition effect of metal ions on beta amylase activity was studied. The inhibitor-binding constant (Ki) was determined by spectrophotometric and isothermal titration calorimetric (ITC) methods. The binding of calcium, magnesium and zinc ion as inhibitors at the active site of barley beta amylase was studied at pH = 4.8 (sodium acetate 16 mM) and T = 300K. The Ki and enthalpy of binding for calcium (13.4, 13.1 mM and -14.3 kJ/mol), magnesium (18.6, 17.8mM and -17.7 kJ/mol) and zinc (17.5, 17.7 mM and -20.0 kJ/mol) were found by spectrophotometric and ITC methods respectively.

  5. Abundance ratios of oxygen, neon, and magnesium in solar active regions and flares: The FIP effect

    NASA Technical Reports Server (NTRS)

    Widing, K. G.; Feldman, U.

    1995-01-01

    Relative abundances of oxygen, neon, and magnesium have been derived for a sample of nine solar active regions, flares, and an erupting prominance by combining plots of the ion differential emission measures. The observations were photographed in the 300-600 A range by the Naval Research Laboratory (NRL) spectroheliograph on Skylab. Methods for deriving the Mg/Ne abundance ratio-which measures the separation between the low- first ionization potential (FIP) and high-FIP abundnace plateaus-have been described in previous papers. In this paper we describe the spectroscopic methods for deriving the O/Ne abundance ratio, which gives the ratio between two high-FIP elements. The plot of the O/Ne ratio versus the Mg/Ne ratio in the sample of nine Skylab events is shown. The variation in the Mg/Ne ratio by a factor of 6 is associated with a much smaller range in the O/Ne ratio. This is broadly consistent with the presence of the standard FIP pattern of abundances in the outer atmosphere of the Sun. However, a real change in the relative abundances of oxygen and neon by a factor of 1.5 cannot be excluded.

  6. Magnesium oxide nanoparticles on green activated carbon as efficient CO{sub 2} adsorbent

    SciTech Connect

    Wan Isahak, Wan Nor Roslam; Ramli, Zatil Amali Che; Mohamed Hisham, Mohamed Wahab; Yarmo, Mohd Ambar

    2013-11-27

    This study was focused on carbon dioxide (CO{sub 2}) adsorption ability using Magnesium oxide (MgO) nanoparticles and MgO nanoparticles supported activated carbon based bamboo (BAC). The suitability of MgO as a good CO{sub 2} adsorbent was clarified using Thermodynamic considerations (Gibbs-Helmholtz relationship). The ΔH and ΔG of this reaction were − 117.5 kJ⋅mol{sup −1} and − 65.4 kJ⋅mol{sup −1}, respectively, at standard condition (298 K and 1 atm). The complete characterization of these adsorbent were conducted by using BET, XRD, FTIR, TEM and TPD−CO{sub 2}. The surface areas for MgO nanoparticles and MgO nanoparticles supported BAC were 297.1 m{sup 2}/g and 702.5 m{sup 2}/g, respectively. The MgO nanoparticles supported BAC shown better physical and chemical adsorption ability with 39.8 cm{sup 3}/g and 6.5 mmol/g, respectively. The combination of MgO nanoparticle and BAC which previously prepared by chemical method can reduce CO{sub 2} emissions as well as better CO{sub 2} adsorption behavior. Overall, our results indicate that nanoparticles of MgO on BAC posses unique surface chemistry and their high surface reactivity coupled with high surface area allowed them to approach the goal as an efficient CO{sub 2} adsorbent.

  7. Abundance ratios of oxygen, neon, and magnesium in solar active regions and flares: The FIP effect

    NASA Technical Reports Server (NTRS)

    Widing, K. G.; Feldman, U.

    1995-01-01

    Relative abundances of oxygen, neon, and magnesium have been derived for a sample of nine solar active regions, flares, and an erupting prominance by combining plots of the ion differential emission measures. The observations were photographed in the 300-600 A range by the Naval Research Laboratory (NRL) spectroheliograph on Skylab. Methods for deriving the Mg/Ne abundance ratio-which measures the separation between the low- first ionization potential (FIP) and high-FIP abundnace plateaus-have been described in previous papers. In this paper we describe the spectroscopic methods for deriving the O/Ne abundance ratio, which gives the ratio between two high-FIP elements. The plot of the O/Ne ratio versus the Mg/Ne ratio in the sample of nine Skylab events is shown. The variation in the Mg/Ne ratio by a factor of 6 is associated with a much smaller range in the O/Ne ratio. This is broadly consistent with the presence of the standard FIP pattern of abundances in the outer atmosphere of the Sun. However, a real change in the relative abundances of oxygen and neon by a factor of 1.5 cannot be excluded.

  8. Magnesium oxide nanoparticles on green activated carbon as efficient CO2 adsorbent

    NASA Astrophysics Data System (ADS)

    Wan Isahak, Wan Nor Roslam; Ramli, Zatil Amali Che; Mohamed Hisham, Mohamed Wahab; Yarmo, Mohd Ambar

    2013-11-01

    This study was focused on carbon dioxide (CO2) adsorption ability using Magnesium oxide (MgO) nanoparticles and MgO nanoparticles supported activated carbon based bamboo (BAC). The suitability of MgO as a good CO2 adsorbent was clarified using Thermodynamic considerations (Gibbs-Helmholtz relationship). The ΔH and ΔG of this reaction were - 117.5 kJṡmol-1 and - 65.4 kJṡmol-1, respectively, at standard condition (298 K and 1 atm). The complete characterization of these adsorbent were conducted by using BET, XRD, FTIR, TEM and TPD-CO2. The surface areas for MgO nanoparticles and MgO nanoparticles supported BAC were 297.1 m2/g and 702.5 m2/g, respectively. The MgO nanoparticles supported BAC shown better physical and chemical adsorption ability with 39.8 cm3/g and 6.5 mmol/g, respectively. The combination of MgO nanoparticle and BAC which previously prepared by chemical method can reduce CO2 emissions as well as better CO2 adsorption behavior. Overall, our results indicate that nanoparticles of MgO on BAC posses unique surface chemistry and their high surface reactivity coupled with high surface area allowed them to approach the goal as an efficient CO2 adsorbent.

  9. In vitro anti-foot-and-mouth disease virus activity of magnesium oxide nanoparticles.

    PubMed

    Rafiei, Solmaz; Rezatofighi, Seyedeh Elham; Ardakani, Mohammad Roayaei; Madadgar, Omid

    2015-10-01

    Foot-and-mouth disease (FMD) is an extremely contagious viral disease of cloven-hoofed animals that can lead to huge economic losses in the livestock production. No antiviral therapies are available for treating FMD virus (FMDV) infections in animals. The antiviral effects of magnesium oxide nanoparticles (MgO NPs) on the FMDV were investigated in cell culture. The viability of the cells after MgO NP treatment was determined using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The direct effects of MgO NPs on the FMDV in extracellular (virucidal assay) and also different stages of virus replication (antiviral assay) were evaluated by plaque reduction assay. The results showed that MgO NPs were safe at concentrations up to 250 µg/ml in the Razi Bovine kidney cell line. The treatments with NPs indicated that the MgO NPs exerted in vitro virucidal and antiviral activities. Plaque reduction assay revealed that MgO NPs can inhibit FMDV by more than 90% at the early stages of infection such as attachment and penetration but not after penetration. The results of this study suggested that NPs might be applied locally as an antiviral agent in early stages of infection in susceptible animals.

  10. Does magnesium sulfate delay the active phase of labor in women with premature rupture of membranes? A randomized controlled trial.

    PubMed

    Mirzamoradi, Masoumeh; Behnam, Marzieh; Jahed, Tayebeh; Saleh-Gargari, Soraya; Bakhtiyari, Mahmood

    2014-09-01

    Administration of many drugs including magnesium sulfate (MS) has considerable influences on pregnancy outcomes. The present study investigates the effects of MS administration on reaching the active phase of labor in women with premature rupture of membrane (PROM) and subsequent fetal complications. A double blind, randomized, placebo-controlled trial was performed among primipara women referred to the PROM center in Tehran, Iran between March 2010 and August 2012. Patients were equally allocated into two groups; the intervention group who received MS (n = 46) and the control (placebo) group (n = 46). Both groups received a corticosteroid, 1g oral azithromycin (oral) and 2 g ampicillin (IV) every 6 hours for 48 hours, followed by amoxicillin (500 mg orally 3 times daily) for an additional 5 days. None of the research staff were aware of the treatment allocation of patients in order for blinding purposes. Administration of MS in intervention group increases this period 2.7 times compared to the control group. In women whose gestational age was <30 weeks, MS administration increased the active phase of labor up to 77%. Administration of magnesium sulfate reduced the risk of respiratory distress syndrome significantly (p = 0 .002), without producing any adverse pregnancy outcomes. Magnesium sulfate increases delay in reaching the active phase of labor in mothers with PROM, without producing adverse birth outcomes. (Registration ID in IRCT; IRCT2012091810876N1). Copyright © 2014. Published by Elsevier B.V.

  11. Magnesium deficiency and metabolic syndrome: stress and inflammation may reflect calcium activation.

    PubMed

    Rayssiguier, Yves; Libako, Patrycja; Nowacki, Wojciech; Rock, Edmond

    2010-06-01

    Magnesium (Mg) intake is inadequate in the western diet and metabolic syndrome is highly prevalent in populations around the world. Epidemiological studies suggest that high Mg intake may reduce the risk but the possibility of confounding factors exists, given the strong association between Mg and other beneficial nutriments (vegetables, fibers, cereals). The concept that metabolic syndrome is an inflammatory condition may explain the role of Mg.Mg deficiency results in a stress effect and increased susceptibility to physiological damage produced by stress. Stress activates the hypothalamic-pituitary-adrenal axis (HPA) axis and the sympathetic nervous system. The activation of the renin-angiotensin-aldosterone system is a factor in the development of insulin resistance by increasing oxidative stress. In both humans and rats, aldosteronism results in an immunostimulatory state and leads to an inflammatory phenotype. Stress response induces the release of large quantities of excitatory amino acids and activates the nuclear factor NFkappaB, promoting translation of molecules involved in cell regulation, metabolism and apoptosis. The rise in neuropeptides is also well documented. Stress-induced HPA activation has been identified to play an important role in the preferential body fat accumulation but evidence that Mg is involved in body weight regulation is lacking. One of the earliest events in the acute response to stress is endothelial dysfunction. Endothelial cells actively contribute to inflammation by elaborating cytokines, synthesizing chemical mediators and expressing adhesion molecules. Experimental Mg deficiency in rats induces a clinical inflammatory syndrome characterized by leukocyte and macrophage activation, synthesis of inflammatory cytokines and acute phase proteins, extensive production of free radicals. An increase in extracellular Mg concentration decreases inflammatory effects, while reduction in extracellular Mg results in cell activation. The

  12. Magnesium impacts myosin V motor activity by altering key conformational changes in the mechanochemical cycle.

    PubMed

    Trivedi, Darshan V; Muretta, Joseph M; Swenson, Anja M; Thomas, David D; Yengo, Christopher M

    2013-07-09

    We investigated how magnesium (Mg) impacts key conformational changes during the ADP binding/release steps in myosin V and how these alterations impact the actomyosin mechanochemical cycle. The conformation of the nucleotide binding pocket was examined with our established FRET system in which myosin V labeled with FlAsH in the upper 50 kDa domain participates in energy transfer with mant labeled nucleotides. We examined the maximum actin-activated ATPase activity of MV FlAsH at a range of free Mg concentrations (0.1-9 mM) and found that the highest activity occurs at low Mg (0.1-0.3 mM), while there is a 50-60% reduction in activity at high Mg (3-9 mM). The motor activity examined with the in vitro motility assay followed a similar Mg-dependence, and the trend was similar with dimeric myosin V. Transient kinetic FRET studies of mantdADP binding/release from actomyosin V FlAsH demonstrate that the transition between the weak and strong actomyosin.ADP states is coupled to movement of the upper 50 kDa domain and is dependent on Mg with the strong state stabilized by Mg. We find that the kinetics of the upper 50 kDa conformational change monitored by FRET correlates well with the ATPase and motility results over a wide range of Mg concentrations. Our results suggest the conformation of the upper 50 kDa domain is highly dynamic in the Mg free actomyosin.ADP state, which is in agreement with ADP binding being entropy driven in the absence of Mg. Overall, our results demonstrate that Mg is a key factor in coupling the nucleotide- and actin-binding regions. In addition, Mg concentrations in the physiological range can alter the structural transition that limits ADP dissociation from actomyosin V, which explains the impact of Mg on actin-activated ATPase activity and in vitro motility.

  13. Effects of magnesium ions on recombinant human furin: selective activation of hydrolytic activity upon substrates derived from virus envelope glycoprotein.

    PubMed

    Izidoro, Mario A; Assis, Diego M; Oliveira, Vitor; Santos, Jorge A N; Juliano, Maria A; Lindberg, Iris; Juliano, Luiz

    2010-09-01

    Here we report a detailed analysis of magnesium (Mg²+) ion effects on furin hydrolysis of fluorescent resonance energy transfer decapeptide substrates derived from canonical R-X-K/R-R furin cleavage motifs within certain viral envelope glycoproteins and eukaryotic proproteins. Using virus-derived sequences a selective activation of furin by Mg²+) ions was observed as a result of cooperativity between furin subsites. Furin hydrolysis of the peptides Abz-SRRHKR↓FAGV-Q-EDDnp (from measles virus fusion protein F₀ and Abz-RERRRKKR↓GLFG-Q-EDDnp (from Asian avian influenza A, H5N1) was activated between 60- and 80-fold by MgCl₂. It appears that virus envelope glycoprotein mutations have been selected to increase their susceptibility to furin within cells, a location where Mg²+ is present in adequate concentrations for activation. Both the pH profile of furin and its intrinsic fluorescence were modified by Mg²+ ions, which bind to furin with a K(d) value of 1.1 mM.

  14. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2011-01-01

    Seawater and natural brines accounted for about 54 percent of U.S. magnesium compounds production in 2010. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash-Wendover and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its operation mentioned above.

  15. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2010-01-01

    Seawater and natural brines accounted for about 40 percent of U.S. magnesium compounds production in 2009. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Chemicals in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover, and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta from its operation mentioned above.

  16. Determination of aluminium, silicon and magnesium in geological matrices by delayed neutron activation analysis based on k0 instrumental neutron activation analysis.

    PubMed

    Baidoo, I K; Dampare, S B; Opata, N S; Nyarko, B J B; Akaho, E H K; Quagraine, R E

    2013-12-01

    In this work, concentrations of silicon, aluminium and magnesium in geological matrices were determined by Neutron Activation Analysis based on k0-IAEA software. The optimum activation and delay times were found to be 5 min and 15-20 min respectively for the determination of Si via (29)Si (n,p) (29)Al reaction. The adopted irradiation scheme did not work for the determination of magnesium. Each sample was irradiated under a thermal neutron flux density of 5.0 × 10(11) ncm(-2)s(-1). Cadmium covered activation indicated that a permanent epithermal irradiation site for research reactors would be very useful for routine determination of silicon in environmental samples.

  17. Magnesium Test

    MedlinePlus

    ... Mag Formal name: Magnesium Related tests: Calcium , Potassium , Phosphorus , PTH , Vitamin D At a Glance Test Sample ... checked to help diagnose problems with calcium, potassium, phosphorus , and/or parathyroid hormone – another component of calcium ...

  18. Production of magnesium metal

    DOEpatents

    Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

    2010-02-23

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention further relates to a process for production of magnesium metal or a magnesium compound where an external source of carbon dioxide is not used in any of the reactions of the process. The invention also relates to the magnesium metal produced by the processes described herein.

  19. Comparative study for the removal and destruction of pentachlorophenol using activated magnesium treatment systems.

    PubMed

    Garbou, Amel M; Clausen, Christian A; Yestrebsky, Cherie L

    2017-01-01

    Chlorophenols are highly toxic, environmentally-persistent compounds which have been classified as probable human carcinogens by the United States Environmental Protection Agency. Due to the high toxicity of these compounds, it is necessary to treat water and soils with concentrations of chlorophenols above the detection limit set by regulatory agencies. The aim of this work is to demonstrate the capabilities of using ball-milled magnesium for the dechlorination of PCP. Comparison of dechlorination processes were performed in an attempt to determine the most effective system for degradation of PCP to phenol. Three systems with powerful capabilities of treatment were studied: ball-milled zero-valent magnesium (ZVMg), ball-milled zero-valent magnesium carbon (ZVMg/C), and ball-milled zero-valent magnesium with palladium (ZVMg/Pd). In addition to measuring PCP disappearance, all byproducts were identified and quantified for each degradation system. The results of these studies indicate that all three of the systems degrade PCP within 30 min. The most rapid and complete PCP dechlorination is achieved using ball-milled Mg/Pd and a matrix consisting of at least 0.02 g Mg0/mL ethanol, and 10 μL acetic acid/mL ethanol, in which case 20 ng/μL of PCP was dechlorinated to chlorophenols in approximately 15 min with complete dechlorination achieved in six days. Carbon mass balances of 90.16% for Mg, 94.76% (Mg/C) and 97.05% (Mg/Pd) verify dechlorination was responsible for declining concentrations of PCP. The reactions of PCP degradation and phenol formation were found to follow pseudo-first order kinetics for all systems. Further work will consist of optimization and development of field-scale applications.

  20. Hiding in Plain Sight: The Bimetallic Magnesium Covalent Bond in Enzyme Active Sites.

    PubMed

    Perera, Lalith; Beard, William A; Pedersen, Lee G; Wilson, Samuel H

    2017-01-03

    The transfer of phosphate groups is an essential function of many intracellular biological enzymes. The transfer is in many cases facilitated by a protein scaffold involving two closely spaced magnesium "ions". It has long been a mystery how these "ions" can retain their closely spaced positions throughout enzymatic phosphate transfer: Coulomb's law would dictate large repulsive forces between these ions at the observed distances. Here we show, however, that the electron density can be borrowed from nearby electron-rich oxygens to populate a bonding molecular orbital that is largely localized between the magnesium "ions". The result is that the Mg-Mg core of these phosphate transfer enzymes is surprisingly similar to a metastable [Mg2](2+) ion in the gas phase, an ion that has been identified experimentally and studied with high-level quantum-mechanical calculations. This similarity is confirmed by comparative computations of the electron densities of [Mg2](2+) in the gas phase and the Mg-Mg core in the structures derived from QM/MM studies of high-resolution X-ray crystal structures. That there is a level of covalent bonding between the two Mg "ions" at the core of these enzymes is a novel concept that enables an improved vision of how these enzymes function at the molecular level. The concept is broader than magnesium-other biologically relevant metals (e.g., Mn and Zn) can also form similar stabilizing covalent Me-Me bonds in both organometallic and inorganic crystals.

  1. Comparative study of antifibrotic activity of some magnesium-containing supplements on experimental liver toxicity. Molecular study.

    PubMed

    El-Tantawy, Walid Hamdy; Sabry, Dina; Abd Al Haleem, Ekram Nemr

    2017-01-01

    Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) proteins including collagen that occurs in most types of chronic liver diseases. This study aimed to investigate and compare the therapeutic efficacy of different magnesium (Mg)-containing supplements (formulations A, B, and C) on carbon tetrachloride (CCl4)-induced liver fibrosis in rats. Liver fibrosis was induced by intraperitoneal injection of rats with CCl4 (1:1 in olive oil, 2 mL/kg, three times/week) for 4 weeks, and then rats were orally treated with different Mg-containing supplements (formulations A, B, and C) once daily for another one month. Liver fibrosis was quantified by evaluation of expressions of Collagen I, transforming growth factor β-1 (TGFβ1), platelet-derived growth factor-C (PDGF-C), nuclear factor kappa-β (NF-κβ), and measurement of hepatic collagen (hydroxyproline) level. Also, malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH) level, superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities were estimated. CCl4 administration significantly elevated expressions of the studied genes, hepatic hydroxyproline, MDA, and NO levels and caused depletion of GSH level, decreased SOD, and GST activities when compared with those of their corresponding control, p < 0.05. All magnesium supplements significantly inhibited expressions of the studied genes and attenuated the hepatic hydroxyproline level as compared with those of CCl4-treated group; p < 0.05; for NF-κβ, the highest inhibition was by formulations B and C. Regarding Collagen I, TGFβ1, and hepatic hydroxyproline content, the highest inhibition was by Formulation C, and Formulation A revealed highest inhibition for PDGF-C. All magnesium supplements revealed normalization of oxidant and antioxidants parameters. Histopathological examination supports the biochemical and molecular findings. Mg supplements were effective in the treatment of hepatic CCl4-induced fibrosis-rat model.

  2. Evidence for a hydroxide ion bridging two magnesium ions at the active site of the hammerhead ribozyme.

    PubMed Central

    Hermann, T; Auffinger, P; Scott, W G; Westhof, E

    1997-01-01

    In the presence of magnesium ions, cleavage by the hammerhead ribozyme RNA at a specific residue leads to 2'3'-cyclic phosphate and 5'-OH extremities. In the cleavage reaction an activated ribose 2'-hydroxyl group attacks its attached 3'-phosphate. Molecular dynamics simulations of the crystal structure of the hammerhead ribozyme, obtained after flash-freezing of crystals under conditions where the ribozyme is active, provide evidence that a mu-bridging OH-ion is located between two Mg2+ions close to the cleavable phosphate. Constrained simulations show further that a flip from the C3'- endo to the C2'- endo conformation of the ribose at the cleavable phosphate brings the 2'-hydroxyl in proximity to both the attacked phosphorous atom and the mu-bridging OH-ion. Thus, the simulations lead to a detailed new insight into the mechanism of hammerhead ribozyme cleavage where a mu-hydroxo bridged magnesium cluster, located on the deep groove side, provides an OH-ion that is able to activate the 2'-hydroxyl nucleophile after a minor and localized conformational change in the RNA. PMID:9254698

  3. Magnesium Elevation Promotes Neuronal Differentiation While Suppressing Glial Differentiation of Primary Cultured Adult Mouse Neural Progenitor Cells through ERK/CREB Activation

    PubMed Central

    Liao, Wang; Jiang, Mujun; Li, Mei; Jin, Congli; Xiao, Songhua; Fan, Shengnuo; Fang, Wenli; Zheng, Yuqiu; Liu, Jun

    2017-01-01

    This study aimed to explore the influence of magnesium elevation on fate determination of adult neural progenitor cells (aNPCs) and the underlying mechanism in vitro. Adult neurogenesis, which is the generation of functional neurons from neural precursors, occurs throughout life in restricted anatomical regions in mammals. Magnesium is the fourth most abundant ion in mammals, and its elevation in the brain has been shown to enhance memory and synaptic plasticity in vivo. However, the effects of magnesium on fate determination of aNPCs, which are vital processes in neurogenesis, remain unknown. NPCs isolated from the dentate gyrus of adult C57/BL6 mice were induced to differentiate in a medium with varying magnesium concentrations (0.6, 0.8, and 1.0 mM) and extracellular signal-regulated kinase (ERK) inhibitor PD0325901. The proportion of cells that differentiated into neurons and glial cells was evaluated using immunofluorescence. Quantitative real-time polymerase chain reaction and Western blot methods were used to determine the expression of β-III tubulin (Tuj1) and glial fibrillary acidic protein (GFAP). The activation of ERK and cAMP response element-binding protein (CREB) was examined by Western blot to reveal the underlying mechanism. Magnesium elevation increased the proportion of Tju1-positive cells and decreased the proportion of GFAP-positive cells. Also, the expression of Tuj1 was upregulated, whereas the expression of GFAP was downregulated. Moreover, magnesium elevation enhanced the activation of both ERK and CREB. Treatment with PD0325901 reversed these effects in a dose-dependent manner. Magnesium elevation promoted neural differentiation while suppressing glial cell differentiation, possibly via ERK-induced CREB activation. PMID:28280456

  4. Magnesium in sea water: an electrode measurement.

    PubMed

    Thompson, M E

    1966-08-19

    Magnesium ion in standard I.A.P.O. sea water was measured with a magnesium-sensitive electrode. The results, presented either as magnesiumion activity (0.017) or as the amount of ionized magnesium (0.048M or about 90 percent of the total magnesium), agree well with the data from the chemical model for sea water proprosed by Garrels and Thompson.

  5. Production of magnesium metal

    DOEpatents

    Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

    2012-04-10

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention also relates to the magnesium metal produced by the processes described herein.

  6. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  7. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2002-01-01

    Seawater and natural brines accounted for about 60% of US magnesium compounds production in 2001. Dead-burned and caustic-calcined magnesias were recovered from seawater in Florida by Premier Chemicals. They were also recovered from Michigan well brines by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And Premier Chemicals recovered dead-burned and caustic-calcined magnesias from magnesite in Nevada. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  8. Comparison of esomeprazole enteric-coated capsules vs esomeprazole magnesium in the treatment of active duodenal ulcer: A randomized, double-blind, controlled study

    PubMed Central

    Liang, Xiao-Yan; Gao, Qing; Gong, Neng-Ping; Tang, Li-Ping; Wang, Pi-Long; Tao, Xiao-Hong

    2008-01-01

    AIM: To evaluate the efficacy and tolerability of two different preparations of esomeprazole in healing duodenal ulcers. METHODS: A total of 60 patients with active duodenal ulcers were enrolled and randomized to receive esomeprazole enteric-coated capsules (40 mg) or esomeprazole magnesium (40 mg), once daily, for 4 consecutive wk, with ulcer healing being monitored by endoscopy. Safety and tolerability were also assessed. RESULTS: Fifty seven patients completed the whole trial. The ulcer healing rates at the end of wk 2 were 86.7% and 85.2% in the esomeprazole enteric-coated capsules and esomeprazole magnesium groups, respectively (P = 0.8410), and reached 100% at the end of wk 4 in both groups. Symptom relief at the end of wk 2 was 90.8% in the esomeprazole enteric-coated capsules group and 86.7% in the esomeprazole magnesium group (P = 0.5406); at the end of wk 4 symptom relief was 95.2% and 93.2%, respectively (P = 0.5786). Adverse events occurred in 16.7% of the esomeprazole enteric-coated capsules group and 14.8% of the esomeprazole magnesium group (P = 1.0000). CONCLUSION: The efficacies of esomeprazole enteric-coated capsules and esomeprazole magnesium in healing duodenal ulcer lesions and relieving gastrointestinal symptoms are equivalent. The tolerability and safety of both drugs were comparable. PMID:18350637

  9. Comparison of esomeprazole enteric-coated capsules vs esomeprazole magnesium in the treatment of active duodenal ulcer: a randomized, double-blind, controlled study.

    PubMed

    Liang, Xiao-Yan; Gao, Qing; Gong, Neng-Ping; Tang, Li-Ping; Wang, Pi-Long; Tao, Xiao-Hong

    2008-03-28

    To evaluate the efficacy and tolerability of two different preparations of esomeprazole in healing duodenal ulcers. A total of 60 patients with active duodenal ulcers were enrolled and randomized to receive esomeprazole enteric-coated capsules (40 mg) or esomeprazole magnesium (40 mg), once daily, for 4 consecutive wk, with ulcer healing being monitored by endoscopy. Safety and tolerability were also assessed. Fifty seven patients completed the whole trial. The ulcer healing rates at the end of wk 2 were 86.7% and 85.2% in the esomeprazole enteric-coated capsules and esomeprazole magnesium groups, respectively (P = 0.8410), and reached 100% at the end of wk 4 in both groups. Symptom relief at the end of wk 2 was 90.8% in the esomeprazole enteric-coated capsules group and 86.7% in the esomeprazole magnesium group (P = 0.5406); at the end of wk 4 symptom relief was 95.2% and 93.2%, respectively (P = 0.5786). Adverse events occurred in 16.7% of the esomeprazole enteric-coated capsules group and 14.8% of the esomeprazole magnesium group (P = 1.0000). The efficacies of esomeprazole enteric-coated capsules and esomeprazole magnesium in healing duodenal ulcer lesions and relieving gastrointestinal symptoms are equivalent. The tolerability and safety of both drugs were comparable.

  10. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

  11. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida; from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties, and Rohm & Haas; and from magnesite in Nevada by Premier Chemicals. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  12. Intracellular and extracellular blood magnesium fractions in hemodialysis patients; is the ionized fraction a measure of magnesium excess?

    PubMed

    Huijgen, H J; Sanders, R; van Olden, R W; Klous, M G; Gaffar, F R; Sanders, G T

    1998-03-01

    To establish the best measure for determining magnesium overload, we measured ionized and total magnesium in serum and mononuclear blood cells and total magnesium in erythrocytes in blood of 23 hemodialysis patients, known for their disturbed magnesium homeostasis. When comparing the mean magnesium values obtained in the patient population with those of a control population, all of these magnesium markers, including the biologically active fractions, were significantly (P < 0.05) increased. Because serum total magnesium was not increased in all dialysis patients studied, the population was divided into two groups, according to total serum magnesium > 1.0 mmol/L or less than that. Results in these two populations showed that ionized serum magnesium and ionized magnesium in mononuclear blood cells might give a better indication about the magnesium status of the tested patients than the currently used total serum magnesium data. However, neither of the two markers, especially ionized serum magnesium, was able to discriminate fully between normal magnesium homeostasis and magnesium excess. We therefore conclude that the two ionized magnesium markers offer minimal advantage for this discrimination, and that the total magnesium concentration in serum remains the measurement of choice.

  13. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2003-01-01

    Seawater and natural brines accounted for about 60 percent of U.S. magnesium compounds production during 2002. Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida. They were also recovered from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And they were recovered from magnesite in Nevada by Premier Chemicals.

  14. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, seawater and natural brines accounted for 51% of US magnesium compounds production. World magnesia production was estimated to be 14.5 Mt. Most of the production came from China, North Korea, Russia and Turkey. Although no specific production figures are available, Japan and the United States are estimated to account for almost one-half of the world's capacity from seawater and brines.

  15. Effects of manganese, calcium, magnesium and zinc on nickel-induced suppression of murine natural killer cell activity

    SciTech Connect

    Smialowicz, R.J.; Rogers, R.R.; Riddle, M.M.; Luebke, R.W.; Fogelson, L.D.; Rowe, D.G.

    1987-01-01

    The effects that divalent metals have on nickel-induced suppression of natural killer (NK) cell activity were studied in mice. Male CBA/J mice were given a single intramuscular injection of the following: nickel chloride, 4.5-36 ..mu..g/g; manganese chloride, 20-80 ..mu..g/g; magnesium acetate, 50-200 ..mu..g/g; zinc acetate, 2-8 ..mu..g/g; or calcium acetate, 12.5-50 ..mu..g/g. Twenty-four hours after metal injection, splenic NK cell activity was assessed using a /sup 51/Cr-release assay. Ni significantly suppressed NK activity, while Mn significantly enhanced NK activity. No alteration in NK activity was observed in mice injected with Mg, Ca, or Zn. The injection of Ni and Mn in combination at a single site resulted in the enhancement of NK activity, although this enhancement was at a level below that observed following the injection of Mn alone. Injection of Mg, Zn, or Ca in combination with Ni did not affect NK activity compared to saline controls. In contrast, the injection of Ni in one thigh followed immediately by Mn, Mg, Ca, or Zn into the other thigh resulted in significant suppression of NK activity for all metals compared with saline controls. An interesting finding was that the injection of Ni followed immediately by Mn into the opposite thigh resulted in even greater reduction in NK activity than Ni alone. Suppression of NK activity by Ni and Mn injected at separate sites was not seen when Mn injection preceded Ni injection by 1 h.

  16. Biophysical characterization and activity analysis of nano-magnesium supplemented cellulase obtained from a psychrobacterium following graphene oxide immobilization.

    PubMed

    Dutta, N; Biswas, S; Saha, M K

    2016-12-01

    Cellulase enzyme was purified from a psychrophilic strain of Bacillus subtilis obtained from east Himalayan mountains. The native enzyme showed optimum activity at 15°C and pH 8.0.The Magnesium oxide nanoparticle (MgN) supplemented enzyme when immobilized on graphene oxide nanosupport (GO), via glutaraldehyde as cross linker, showed 2.98 folds increase in enzymatic activity at 8°C and more than 3.5 folds activity increment at 90°C. The MgN-cel on graphene (GO-MgN-cel) showed a decrease in Km by 6.7 folds at 8°C and 34 folds at 90°C. GO-MgN-cel showed 5 fold and 4.7 fold increase in Vmax at 8°C and 90°C respectively than the untreated enzyme.When compared to native enzyme, GO-MgN-cel had t1/2 (half life) and Ed increased by 72.5 fold and 2.48 fold respectively at 90°C; and 41.6 fold and 2.19 fold respectively at 8°C. Enzymatic activity of GO-MgN-cel was retained even after 12 repeated uses and showed storage stability at 4°C for more than 120days. This nanoparticle assisted immobilization technique can be utilized in bioprocessing industries which require functioning at these extreme ranges of temperature.

  17. Low magnesium level

    MedlinePlus

    Low magnesium level is a condition in which the amount of magnesium in the blood is lower than normal. The medical ... that convert or use energy ( metabolism ). When the level of magnesium in the body drops below normal, ...

  18. Synthesis of a novel alkali-activated magnesium slag-based nanostructural composite and its photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Zhang, Yao Jun; Kang, Le; Liu, Li Cai; Si, Hai Xiao; Zhang, Ji Fang

    2015-03-01

    A novel type of alkali-activated magnesium slag-based nanostructural composite (AMSNC) co-loaded bimetallic oxide semiconductors of NiO and CuO were synthesized by alkaline activation, ion exchange and wet co-impregnation methods, and then firstly employed as a photocatalyst for the degradation of indigo carmine dye. The XRD, TEM and HRTEM results revealed that CuO in the form of tenorite with mean particle size of about 15 nm and NiO in amorphous phase dispersed on the surface of AMSNC support. The decrease of photoluminescence with increasing amount of NiO and CuO demonstrated that the recombination of photogenerated electrons-holes pairs was prevented when the photogenerated electrons transferred from the metal oxide semiconductor to the AMSNC matrix. The 10(NiO + CuO)/AMSNC specimen showed that the photocatalytic degradation efficiency was up to 100% under UV irradiation for 1 h due to the synergistic effect between the AMSNC and active species of NiO and CuO. The mesoporous structures of specimens acted as critical role for the adsorption of dye molecules, and the photocatalytic degradation of indigo carmine dye obeyed first-order reaction kinetics. A degradation mechanism of photocatalytic oxidation was proposed in the paper.

  19. Self-assembled air-stable magnesium hydride embedded in 3-D activated carbon for reversible hydrogen storage.

    PubMed

    Shinde, S S; Kim, Dong-Hyung; Yu, Jin-Young; Lee, Jung-Ho

    2017-06-01

    The rational design of stable, inexpensive catalysts with excellent hydrogen dynamics and sorption characteristics under realistic environments for reversible hydrogen storage remains a great challenge. Here, we present a simple and scalable strategy to fabricate a monodispersed, air-stable, magnesium hydride embedded in three-dimensional activated carbon with periodic synchronization of transition metals (MHCH). The high surface area, homogeneous distribution of MgH2 nanoparticles, excellent thermal stability, high energy density, steric confinement by carbon, and robust architecture of the catalyst resulted in a noticeable enhancement of the hydrogen storage performance. The resulting MHCH-5 exhibited outstanding hydrogen storage performance, better than that of most reported Mg-based hydrides, with a high storage density of 6.63 wt% H2, a rapid kinetics loading in <5 min at 180 °C, superior reversibility, and excellent long-term cycling stability over ∼435 h. The significant reduction of the enthalpy and activation energy observed in the MHCH-5 demonstrated enhancement of the kinetics of de-/hydrogenation compared to that of commercial MgH2. The origin of the intrinsic hydrogen thermodynamics was elucidated via solid state (1)H NMR. This work presents a readily scaled-up strategy towards the design of realistic catalysts with superior functionality and stability for applications in reversible hydrogen storage, lithium ion batteries, and fuel cells.

  20. The TMS Magnesium Committee: Committed to the Advancement of Global Magnesium Technology

    SciTech Connect

    Sillekens, Wim H.; Nyberg, Eric A.

    2011-04-21

    The TMS Magnesium Committee was established in the year 2000 as a spin-off of the Reactive Metals Committee, triggered by the strong global growth of magnesium being used in a variety of structural lightweight applications since the mid-1990’s. Since then the committee has seen a distinct development in terms of size, participation and focus. The article at hand outlines this development by recapitulating the output of its two main activities: the annual Magnesium Technology Symposia and the JOM Special Issues dedicated to magnesium research and development. Further records on the Magnesium Committee are available from the committee homepage (accessible through http://members.tms.org).

  1. Magnesium(I) Dimers Bearing Tripodal Diimine-Enolate Ligands: Proficient Reagents for the Controlled Reductive Activation of CO2 and SO2.

    PubMed

    Boutland, Aaron J; Pernik, Indrek; Stasch, Andreas; Jones, Cameron

    2015-10-26

    The first examples of magnesium(I) dimers bearing tripodal ligands, [(Mg{κ(3) -N,N',O-(ArNCMe)2 (OCCPh2 )CH})2 ] [Ar=2,6-iPr2 C6 H3 (Dip) 7, 2,6-Et2 C6 H3 (Dep) 8, or mesityl (Mes) 9] have been prepared by post-synthetic modification of the β-diketiminato ligands of previously reported magnesium(I) systems, using diphenylketene, OCCPh2 . In contrast, related reactions between β-diketiminato magnesium(I) dimers and the isoelectronic ketenimine, MesNCCPh2 , resulted in reductive insertion of the substrate into the MgMg bond of the magnesium(I) reactant, and formation of [{(Nacnac)Mg}2 {μ-κ(2) -N,C-(Mes)NCCPh2 }] (Nacnac=[(ArNCMe)2 CH](-) ; Ar=Dep 10 or Mes 11). Reactions of the four-coordinate magnesium(I) dimer 8 with excess CO2 are readily controlled, and cleanly give carbonate [(LMg)2 (μ-κ(2) :κ(2) -CO3 )] 12 (L=[κ(3) -N,N',O-(DepNCMe)2 (OCCPh2 )CH](-) ; thermodynamic product), or oxalate [(LMg)2 (μ-κ(2) :κ(2) -C2 O4 )] 13 (kinetic product), depending on the reaction temperature. Compound 12 and CO are formed by reductive disproportionation of CO2 , whereas 13 results from reductive coupling of two molecules of the gas. Treatment of 8 with an excess of N2 O cleanly gives the μ-oxo complex [(LMg)2 (μ-O)] 14, which reacts facilely with CO2 to give 12. This result presents the possibility that 14 is an intermediate in the formation of 12 from the reaction of 8 and CO2 . In contrast to its reactions with CO2 , 8 reacts with SO2 over a wide temperature range to give only one product; the first example of a magnesium dithionite complex, [(LMg)2 (μ-κ(2) :κ(2) -S2 O4 )] 16, which is formed by reductive coupling of two molecules of SO2 , and is closely related to f-block metal dithionite complexes derived from similar SO2 reductive coupling processes. On the whole, this study strengthens previously proposed analogies between the reactivities of magnesium(I) systems and low-valent f-block metal complexes, especially with respect to small

  2. Sulla carnosa modulates root invertase activity in response to the inhibition of long-distance sucrose transport under magnesium deficiency.

    PubMed

    Farhat, N; Smaoui, A; Maurousset, L; Porcheron, B; Lemoine, R; Abdelly, C; Rabhi, M

    2016-11-01

    Being the principal product of photosynthesis, sucrose is involved in many metabolic processes in plants. As magnesium (Mg) is phloem mobile, an inverse relationship between Mg shortage and sugar accumulation in leaves is often observed. Mg deficiency effects on carbohydrate contents and invertase activities were determined in Sulla carnosa Desf. Plants were grown hydroponically at different Mg concentrations (0.00, 0.01, 0.05 and 1.50 mM Mg) for one month. Mineral analysis showed that Mg contents were drastically diminished in shoots and roots mainly at 0.01 and 0.00 mM Mg. This decline was adversely associated with a significant increase of sucrose, fructose and mainly glucose in shoots of plants exposed to severe deficiency. By contrast, sugar contents were severely reduced in roots of these plants indicating an alteration of carbohydrate partitioning between shoots and roots of Mg-deficient plants. Cell wall invertase activity was highly enhanced in roots of Mg-deficient plants, while the vacuolar invertase activity was reduced at 0.00 mM Mg. This decrease of vacuolar invertase activity may indicate the sensibility of roots to Mg starvation resulting from sucrose transport inhibition. (14) CO2 labeling experiments were in accordance with these findings showing an inhibition of sucrose transport from source leaves to sink tissues (roots) under Mg depletion. The obtained results confirm previous findings about Mg involvement in photosynthate loading into phloem and add new insights into mechanisms evolved by S. carnosa to cope with Mg shortage in particular the increase of the activity of cell wall invertase.

  3. Nano-magnesium aided activity enhancement and biophysical characterization of a psychrophilic α-amylase immobilized on graphene oxide nanosupport.

    PubMed

    Dutta, Nalok; Biswas, Subrata; Saha, Malay Kumar

    2017-03-03

    In the current literature we have devised an immobilization technique for conferring psychrostability to a cold active α-amylase (amy) enzyme by the use of magnesium nanoparticle (MgNP) and graphene oxide (GO). The GO-MgNP-amy nanocomposite showed enhanced enzymatic activity and thermostability at both upper (90°C) and lower (8°C) temperature extremes. The GO-MgNP-amy showed increased affinity towards substrate, reflected in the decrease in its Km by 2.35 and 14.9-fold at 8°C and 90°C, respectively, than the untreated enzyme. GO-MgNP-amy showed 2.34-fold and 4.29-fold increase in Vmax at 8°C and 90°C, respectively, than the untreated enzyme. When compared to native enzyme at 90°C, GO-MgNP-amy had t1/2 (half life) increased by 44-fold with simultaneous increase in Ed by 1.9-fold. Again at 8°C, GO-MgNP-amy had t1/2 increased by 6.48-fold with simultaneous increase in Ed by 2.21-fold when compared to the native enzyme. The enzymatic activity of GO-MgNP-amy was retained even after 12 repeated uses and showed storage stability at 4°C for more than 120 days. The ability of GO-MgNP to sustain and aggravate enzyme activity and stability at temperatures beyond the optimal range can be utilized in bioprocessing industries which requires functioning at these extreme ranges of temperature.

  4. Dual ions implantation of zirconium and nitrogen into magnesium alloys for enhanced corrosion resistance, antimicrobial activity and biocompatibility.

    PubMed

    Cheng, Mengqi; Qiao, Yuqin; Wang, Qi; Qin, Hui; Zhang, Xianlong; Liu, Xuanyong

    2016-12-01

    Biodegradable magnesium-based alloys have shown great potential for medical applications due to their superior biological performances and mechanical properties. However, on one hand, some side effects including inferior biocompatibility, a local high-alkaline environment and gas cavities caused by a rapid corrosion rate, hinder their clinical application. On the other hand, it is also necessary to endow Mg alloys with antibacterial properties, which are crucial for clinic orthopedic applications. In this study, Zr and N ions are simultaneously implanted into AZ91 Mg alloys by plasma immersion ion implantation (PIII). A modified layer with a thickness of approximately 80nm is formed on the surface of AZ91 Mg alloys, and the hydrophobicity and roughness of these AZ91 Mg alloys obviously increase after Zr and N implantation. The in vitro evaluations including corrosion resistance tests, antimicrobial tests and cytocompatibility and alkaline phosphatase (ALP) activity tests, revealed that the dual ions implantation of Zr and N not only enhanced the corrosion resistance of the AZ91 Mg alloy but also provided better antimicrobial properties in vitro. Furthermore, the formation of biocompatible metal nitrides and metal oxides layer in the near surface of the Zr-N-implanted AZ91 Mg alloy provided a favorable implantation surface for cell adhesion and growth, which in return further promoted the bone formation in vivo. These promising results suggest that the Zr-N-implanted AZ91 Mg alloy shows potential for future application in the orthopedic field.

  5. Temporal changes in circulating P-selectin, plasminogen activator inhibitor-1, magnesium, and creatine kinase after percutaneous coronary intervention*

    PubMed Central

    Ying, Shu-qin; Xiang, Mei-xiang; Fang, Lu; Wang, Jian-an

    2010-01-01

    Objective: This study aims to determine the mechanisms underlying restenosis and ischemia-reperfusion injury of the myocardium after percutaneous coronary intervention (PCI). Methods: The present study examined serial changes (5 min, 30 min, 2 h, 6 h, and 24 h after PCI) in circulating P-selectin, plasminogen activator inhibitor-1 (PAI-1), magnesium (Mg), and creatine kinase-myocardial band fraction (CK-MB) levels, which may be associated with restenosis and myocardial injury in patients undergoing PCI. The occurrence rates of major adverse cardiovascular events were collected over a six-month follow-up. Results: PCI induced an early elevation of P-selectin, which correlated positively with the inflation pressure used in the PCI procedure. PCI also caused a significant and sustained decrease in serum Mg in PCI patients, without an effect on PAI-1. An increase in CK-MB was observed in PCI patients, although values were within normal reference range. In addition, elevated P-selectin and decreased Mg measured shortly after the coronary angioplasty procedure were associated with recurrent treatment and heart failure, respectively. Conclusions: Our study demonstrates that PCI induces temporal changes of P-selectin, Mg, and CK-MB, which may be involved in restenosis and ischemia-reperfusion injury. These findings highlight the need for using antiplatelet therapy and Mg to reduce the risks associated with PCI. PMID:20669347

  6. Corrosion in Magnesium and a Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Akavipat, Sanay

    Magnesium and a magnesium alloy (AZ91C) have been ion implanted over a range of ions energies (50 to 150 keV) and doses (1 x 10('16) to 2 x 10('17) ions/cm('2)) to modify the corrosion properties of the metals. The corrosion tests were done by anodic polarization in chloride -free and chloride-containing aqueous solutions of a borated -boric acid with a pH of 9.3. Anodic polarization measurements showed that some implantations could greatly reduce the corrosion current densities at all impressed voltages and also increased slightly the pitting potential, which indicated the onset of the chloride attack. These improvements in corrosion resistance were caused by boron implantations into both types of samples. However, iron implantations were found to improve only the magnesium alloy. To study the corrosion in more detail, Scanning Auger Microprobe Spectrometer (SAM), Scanning Electron Microscope (SEM) with an X-ray Energy Spectrometry (XES) attachment, and Transmission Electron Microscope (TEM) measurements were used to analyze samples before, after, and at various corrosion stages. In both the unimplanted pure magnesium and AZ91C samples, anodic polarization results revealed that there were three active corrosion stages (Stages A, C, and E) and two passivating stages (Stages B and D). Examination of Stages A and B in both types of samples showed that only a mild, generalized corrosion had occurred. In Stage C of the TD samples, a pitting breakdown in the initial oxide film was observed. In Stage C of the AZ91C samples, galvanic and intergranular attack around the Mg(,17)Al(,12) intermetallic islands and along the matrix grain boundaries was observed. Stage D of both samples showed the formation of a thick, passivating oxygen containing, probably Mg(OH)(,2) film. In Stage E, this film was broken down by pits, which formed due to the presence of the chloride ions in both types of samples. Stages A through D of the unimplanted samples were not seen in the boron or iron

  7. The chlorophyll-deficient golden leaf mutation in cucumber is due to a single nucleotide substitution in CsChlI for magnesium chelatase I subunit

    USDA-ARS?s Scientific Manuscript database

    The chlorophyll gives the green color in plants. Any mutations in chloroplhyll biosynthesis or regulation may result in colr changes. Leaf color mutants are common in higher plants, which can be used as markers in crop breeding or as a tool in understanding regulatory mechanisms in chlorophyll biosy...

  8. Alkalization is responsible for antibacterial effects of corroding magnesium.

    PubMed

    Rahim, Muhammad Imran; Eifler, Rainer; Rais, Bushra; Mueller, Peter P

    2015-11-01

    Magnesium alloys are presently investigated as potential medical implant materials for temporary applications. Magnesium has been reported to have antibacterial activities and could therefore be used to prevent antibiotic treatment-resistant bacterial implant infections. For characterizing the effects of magnesium on infectious bacteria, bioluminescent S. aureus or P. aeruginosa were employed. The proliferation of both types of bacteria was suppressed in the presence of metallic magnesium and also in aqueous magnesium corrosion extracts. Of the two soluble corrosion products, magnesium ions were well tolerated while antibacterial activities correlated with increased pH levels of the supernatants. The alkaline pH alone was sufficient for the antibacterial effects which were completely abolished when the pH of the corrosion supernatants was neutralized. These results demonstrate that pH increases are necessary and sufficient for the antibacterial activity of metallic magnesium. In an animal model magnesium implants showed an enhanced but variable resistance to bacterial colonization.

  9. Phosphatidylinositol 4,5-bisphosphate (PIP(2)) controls magnesium gatekeeper TRPM6 activity.

    PubMed

    Xie, Jia; Sun, Baonan; Du, Jianyang; Yang, Wenzhong; Chen, Hsiang-Chin; Overton, Jeffrey D; Runnels, Loren W; Yue, Lixia

    2011-01-01

    TRPM6 is crucial for human Mg2+ homeostasis as patients carrying TRPM6 mutations develop hypomagnesemia and secondary hypocalcemia (HSH). However, the activation mechanism of TRPM6 has remained unknown. Here we demonstrate that phosphatidylinositol-4,5-bisphophate (PIP2) controls TRPM6 activation and Mg2+ influx. Stimulation of PLC-coupled M1-receptors to deplete PIP2 potently inactivates TRPM6. Translocation of over-expressed 5-phosphatase to cell membrane to specifically hydrolyze PIP2 also completely inhibits TRPM6. Moreover, depolarization-induced-activation of the voltage-sensitive-phosphatase (Ci-VSP) simultaneously depletes PIP2 and inhibits TRPM6. PLC-activation induced PIP2-depletion not only inhibits TRPM6, but also abolishes TRPM6-mediated Mg2+ influx.Furthermore, neutralization of basic residues in the TRP domain leads to nonfunctional or dysfunctional mutants with reduced activity by PIP2, suggesting that they are likely to participate in interactions with PIP2.Our data indicate that PIP2 is required for TRPM6 channel function; hydrolysis of PIP2 by PLC-coupled hormones/agonists may constitute an important pathway for TRPM6 gating, and perhaps Mg2+ homeostasis.

  10. Ionized and total magnesium concentration in patients with severe preeclampsia-eclampsia undergoing magnesium sulfate therapy.

    PubMed

    Aali, Bibi Shahnaz; Khazaeli, Payam; Ghasemi, Fatemeh

    2007-04-01

    As ionized magnesium is the active form of magnesium and exerts a therapeutic effect, the present study was performed to determine the levels and correlations between ionized and total magnesium under baseline and therapeutic conditions in patients with severe preeclampsia and eclampsia receiving magnesium sulfate. Fifty singleton patients with severe preeclampsia received a loading dose of 4 g of magnesium sulfate, followed by 2 g per hour as maintenance dose until 24 h after delivery, or 24 h after the last seizure in case of postpartum convulsions. Serial blood samples were taken before magnesium sulfate infusion, 30 min and 240 min after the initiation of the infusion and 4 h after the discontinuation of the drug. Data were analyzed by repeated measure ANOVA and paired t-test. Baseline levels of total and ionized magnesium were 2.4+/-0.6 mEq/L and 1.3+/-0.5 mEq/L (mean+/-SD), respectively. Putative level of 4 mEq/L of total magnesium was not obtained in up to 42% of patients during the treatment. There was not any significant correlation between the two forms of magnesium under baseline and therapeutic conditions. Despite the effectiveness of the standard regimen of magnesium sulfate in the treatment and prevention of eclamptic seizures, it can not provide the proposed therapeutic level of magnesium in all patients. With respect to the lack of correlation between ionized and total magnesium, further studies are necessary to investigate the superiority of measurement of ionized, rather than total magnesium, for titration of therapeutic magnesium sulfate infusion.

  11. Pharmacokinetics of ionized versus total magnesium in subjects with preterm labor and preeclampsia.

    PubMed

    Taber, Evan B; Tan, Lily; Chao, Conrad R; Beall, Marie H; Ross, Michael G

    2002-05-01

    Intravenous magnesium sulfate is widely used in obstetrics for the treatment of both preterm labor and preeclampsia. Although therapeutic levels of total magnesium have been proposed, the levels remain controversial. Because the active form of magnesium is the free or ionized form, it is essential to determine whether ionized magnesium and total magnesium levels are highly correlated in vivo. We sought to examine the correlation between ionized magnesium and total magnesium under basal and therapeutic conditions and to define the initiation and elimination pharmacokinetics of both forms during intravenous magnesium sulfate infusion. Twenty-four singleton pregnant patients who were candidates for magnesium sulfate were studied (preterm labor, 15; preeclampsia, 9). Serial blood samples were taken before the magnesium sulfate infusion, during the first 4 hours after the initiation of magnesium sulfate infusion and for 4 hours after the discontinuation of the infusion. Baseline levels of total magnesium and ionized magnesium were not different between patients with preterm labor and with preeclampsia. Among patients with preeclampsia, although not patients with preterm labor, the initial apparent volume of distribution was significantly smaller for total magnesium than for ionized magnesium (16,397 +/- 1441 vs 23,856 +/- 2745 mL, respectively; P =.03), and the elimination half-life was greater for total magnesium as compared to ionized magnesium (707 +/- 160 vs 313 +/- 29 minutes;P <.05). Linear regression analysis demonstrated a lack of correlation between ionized magnesium and total magnesium during the pretreatment period and during the steady state infusion for both preterm labor and preeclampsia. The measurement of total magnesium may not be adequate for the titration of therapeutic magnesium infusions in patients with preeclampsia or preterm labor because of the lack of correlation between total magnesium and the physiologically active ionized magnesium. Further

  12. Magnesium-Dependent Active-Site Conformational Selection in the Diels-Alderase Ribozyme

    SciTech Connect

    Berezniak, Tomasz; Zahran, Mai; Imhof, Petra; Jaeschke, Andres; Smith, Jeremy C

    2010-10-01

    The Diels-Alderase ribozyme, an in vitro-evolved ribonucleic acid enzyme, accelerates the formation of carbon-carbon bonds between an anthracene diene and a maleimide dienophile in a [4 + 2] cycloaddition, a reaction with broad application in organic chemistry. Here, the Diels-Alderase ribozyme is examined via molecular dynamics (MD) simulations in both crystalline and aqueous solution environments. The simulations indicate that the catalytic pocket is highly dynamic. At low Mg(2+) ion concentrations, inactive states with the catalytic pocket closed dominate. Stabilization of the enzymatically active, open state of the catalytic pocket requires a high concentration of Mg(2+) ions (e.g., 54 mM), with cations binding to specific phosphate sites on the backbone of the residues bridging the opposite strands of the pocket. The free energy profile for pocket opening at high Mg(2+) cation concentration exhibits a double minimum, with a barrier to opening of approximately 5.5 kJ/mol and the closed state approximately 3 kJ/mol lower than the open state. Selection of the open state on substrate binding leads to the catalytic activity of the ribozyme. The simulation results explain structurally the experimental observation that full catalytic activity depends on the Mg(2+) ion concentration

  13. Shielding gas effect to diffusion activities of magnesium and copper on aluminum clad

    NASA Astrophysics Data System (ADS)

    Manurung, Charles SP; Napitupulu, Richard AM

    2017-09-01

    Aluminum is the second most metal used in many application, because of its corrosion resistance. The Aluminum will be damaged in over time if it’s not maintained in good condition. That is important to give protection to the Aluminums surface. Cladding process is one of surface protection methodes, especially for metals. Aluminum clad copper (Al/Cu) or copper clad aluminum (Cu/Al) composite metals have been widely used for many years. These mature protection method and well tested clad metal systems are used industrially in a variety application. The inherent properties and behavior of both copper and aluminum combine to provide unique performance advantages. In this paper Aluminum 2024 series will be covered with Aluminum 1100 series by hot rolling process. Observations will focus on diffusion activities of Mg and Cu that not present on Aluminum 1100 series. The differences of clad material samples is the use of shielding gas during heating before hot rolling process. The metallurgical characteristics will be examined by using optical microscopy. Transition zone from the interface cannot be observed but from Energy Dispersive Spectrometry it’s found that Mg and Cu are diffused from base metal (Al 2024) to the clad metal (Al 1100). Hardness test proved that base metals hardness to interface was decrease.

  14. Differential effects of zinc and magnesium ions on mineralization activity of phosphatidylserine calcium phosphate complexes.

    PubMed

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

    2009-07-01

    Mg(2+) and Zn(2+) are present in the mineral of matrix vesicles (MVs) and biological apatites, and are known to influence the onset and progression of mineral formation by amorphous calcium phosphate (ACP) and hydroxyapatite (HAP). However, neither has been studied systematically for its effect on mineral formation by phosphatidylserine-Ca(2+)-Pi complexes (PS-CPLX), an important constituent of the MV nucleation core. Presented here are studies on the effects of increasing levels of Mg(2+) and Zn(2+) on the process of mineral formation, either when present in synthetic cartilage lymph (SCL), or when incorporated during the formation of PS-CPLX. Pure HAP and PS-CPLX proved to be powerful nucleators, but ACP took much longer to induce mineral formation. In SCL, Mg(2+) and Zn(2+) had significantly different inhibitory effects on the onset and amount of mineral formation; HAP and PS-CPLX were less affected than ACP. Mg(2+) and Zn(2+) caused similar reductions in the rate and length of rapid mineral formation, but Zn(2+) was a more potent inhibitor on a molar basis. When incorporated into PS-CPLX, Mg(2+) and Zn(2+) caused significantly different effects than when present in SCL. Even low, subphysiological levels of Mg(2+) altered the inherent structure of PS-CPLX and markedly reduced its ability to induce and propagate mineral formation. Incorporated Zn(2+) caused significantly less effect, low (<20 microM) levels causing almost no inhibition. Levels of Zn(2+) present in MVs do not appear to inhibit their nucleational activity.

  15. Effect of acute hyperinsulinemia on magnesium homeostasis in humans.

    PubMed

    Xu, Li Hao Richie; Maalouf, Naim M

    2017-02-01

    Insulin may influence magnesium homeostasis through multiple mechanisms. Acutely, it stimulates the shift of magnesium from plasma into red blood cells and platelets, and in vitro, it stimulates the activity of the TRPM6 channel, a key regulator of renal magnesium reabsorption. We investigated the impact of hyperinsulinemia on magnesium handling in participants with a wide range of insulin sensitivity. Forty-seven participants were recruited, including 34 nondiabetic controls and 13 with type 2 diabetes mellitus. After stabilization under fixed metabolic diet, participants underwent hyperinsulinemic-euglycemic clamp. Serum and urine samples were collected before and during hyperinsulinemia. Change in serum magnesium, urinary magnesium to creatinine (Mg(2)(+) :Cr) ratio, fractional excretion of urinary magnesium (FEMg(2)(+) ), and estimated transcellular shift of magnesium were compared before and during hyperinsulinemia. Hyperinsulinemia led to a small but statistically significant decrease in serum magnesium, and to a shift of magnesium into the intracellular compartment. Hyperinsulinemia did not significantly alter urinary magnesium to creatinine ratio or fractional excretion of urinary magnesium in the overall population, although a small but statistically significant decline in these parameters occurred in participants with diabetes. There was no significant correlation between change in fractional excretion of urinary magnesium and body mass index or insulin sensitivity measured as glucose disposal rate. In human participants, acute hyperinsulinemia stimulates the shift of magnesium into cells with minimal alteration in renal magnesium reabsorption, except in diabetic patients who experienced a small decline in fractional excretion of urinary magnesium. The magnitude of magnesium shift into the intracellular compartment in response to insulin does not correlate with that of insulin-stimulated glucose entry into cells. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Choline Magnesium Trisalicylate

    MedlinePlus

    Choline magnesium trisalicylate is used to relieve the pain, tenderness, inflammation (swelling), and stiffness caused by arthritis ... painful shoulder. It is also used to relieve pain and lower fever. Choline magnesium trisalicylate is in ...

  17. Coagulant Activity of Water-Soluble Moringa oleifera Lectin Is Linked to Lowering of Electrical Resistance and Inhibited by Monosaccharides and Magnesium Ions.

    PubMed

    de Moura, Kézia Santana; da Silva, Hugo Rafael Chaves; Dornelles, Leonardo Prezzi; Coelho, Luana Cassandra Breitenbach Barroso; Napoleão, Thiago Henrique; de Oliveira, Maria Danielly Lima; Paiva, Patrícia Maria Guedes

    2016-12-01

    Moringa oleifera seeds contain a water-soluble lectin [water-soluble M. oleifera lectin (WSMoL)] that has shown coagulant activity. Magnesium ions are able to interfere with the ability of this lectin to bind carbohydrates. In this study, we performed structural characterization of WSMoL and analyzed its effect on the electrical resistance of a kaolin clay suspension in both presence and absence of monosaccharides (N-acetylglucosamine, glucose, or fructose) and magnesium ions. The coagulant activity of WSMoL was monitored by measuring optical density and electrical resistance over a period of 60 min. Native WSMoL had a molecular mass of 60 kDa and exhibited anionic nature (pI 5.5). In sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), it appeared as three polypeptide bands of 30, 20, and 10 kDa. WSMoL reduced the optical density and electrical resistance of the kaolin suspension, which suggests that suspended particles are destabilized and that this is followed by formation of complexes. The coagulant activity of lectin decreased in the presence of Mg(2+) ions and carbohydrates at concentrations that also inhibited hemagglutinating activity. This was most likely due to conformational changes in lectin structure. Our findings suggest that the coagulant activity of WSMoL is enhanced by lowering of electrical resistance of the medium and is impaired by lectin-carbohydrate and lectin-Mg(2+) interactions.

  18. Magnesium and Space Flight.

    PubMed

    Smith, Scott M; Zwart, Sara R

    2015-12-08

    Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4-6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4-6-month space missions.

  19. Magnesium and Space Flight

    PubMed Central

    Smith, Scott M.; Zwart, Sara R.

    2015-01-01

    Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4–6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4–6-month space missions. PMID:26670248

  20. Major Minerals - Calcium, Magnesium, Phosphorus

    USDA-ARS?s Scientific Manuscript database

    Calcium, magnesium and phosphorus are essential elements critically important for the function of the musculoskeletal system, including the formation and transduction of energy and the maintenance of healthy bone. The major calcium concern for physically active healthy middle-aged adults is to consu...

  1. Magnesium industry overview

    SciTech Connect

    Clow, B.B.

    1996-10-01

    Magnesium products provide an excellent strength-to-weight ratio, good fatigue strength, high impact strength, good corrosion resistance, high-speed machinability, and good thermal and electrical conductivities. As a result, applications are expanding in almost every industry. Dozens of automotive components are now made of magnesium, including steering wheels, valve covers, and seat frames. Magnesium alloys are also used in computer housings, in-line roller skates, golf clubs, tennis racquets, and baseball bats. Good strength and stiffness at both room and elevated temperatures make magnesium alloys especially valuable for aerospace applications. This article presents an overview of magnesium technology, world production, increasing demand, and recycling.

  2. Micronized Organic Magnesium Salts Enhance Opioid Analgesia in Rats

    PubMed Central

    Bujalska-Zadrożny, Magdalena; Kulik, Kamila; Ordak, Michał; Sasinowska-Motyl, Małgorzata; Gąsińska, Emilia; de Corde, Anna; Kowalczyk, Agnieszka; Sacharczuk, Mariusz; Naruszewicz, Marek

    2016-01-01

    Purpose As previously reported, magnesium sulphate administered parenterally significantly increased an opioid antinociception in different kinds of pain. Since the typical form of magnesium salts are poorly and slowly absorbed from the gastrointestinal tract we examined whether their micronized form could increase opioids induced antinociception. Methods In behavioural studies on rats morphine, tramadol and oxycodone together with magnesium (lactate dihydrate, hydroaspartate, chloride) in micronized (particles of size D90 < 50 μm) and conventional forms were used. Changes in pain thresholds were determined using mechanical stimuli. The intestinal absorption of two forms of magnesium lactate dihydrate (at the doses of 7.5 or 15 mg ions) in the porcine gut sac model were also compared. Results Micronized form of magnesium lactate dihydrate or hydroaspartate but not chloride (15 mg of magnesium ions kg-1) enhanced the analgesic activity of orally administered opioids, significantly faster and more effective in comparison to the conventional form of magnesium salts (about 40% for oxycodone administered together with a micronized form of magnesium hydroaspartate). Moreover, in vitro studies of transport across porcine intestines of magnesium ions showed that magnesium salts administered in micronized form were absorbed from the intestines to a greater extent than the normal form of magnesium salts. Conclusions The co-administration of micronized magnesium organic salts with opioids increased their synergetic analgesic effect. This may suggest an innovative approach to the treatment of pain in clinical practice. PMID:27792736

  3. Activation of Magnesium Lignosulfonate and Kraft Lignin: Influence on the Properties of Phenolic Resin-Based Composites for Potential Applications in Abrasive Materials.

    PubMed

    Klapiszewski, Lukasz; Jamrozik, Artur; Strzemiecka, Beata; Matykiewicz, Danuta; Voelkel, Adam; Jesionowski, Teofil

    2017-06-08

    Magnesium lignosulfonate and kraft lignin were activated by different oxidizing agents for use in phenolic resin composites used for the production of abrasive components. The physicochemical properties of the oxidized materials were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic mechanical-thermal analysis (DMTA) and inverse gas chromatography (IGC). The homogeneity of the model abrasive composites containing the studied products was assessed based on observations obtained using a scanning electron microscope (SEM). FTIR and XPS analysis of the oxidized products indicated that the activation process leads mainly to the formation of carbonyl groups. The IGC technique was used to assess changes in the surface energy and the acid-base properties of the studied biopolymers. The changes in the acid-base properties suggest that more groups acting as electron donors appear on the oxidized surface of the materials. DMTA studies showed that the model composites with 5% magnesium lignosulfonate oxidized by H₂O₂ had the best thermomechanical properties. Based on the results it was possible to propose a hypothetical mechanism of the oxidation of the natural polymers. The use of such oxidized products may improve the thermomechanical properties of abrasive articles.

  4. Activation of Magnesium Lignosulfonate and Kraft Lignin: Influence on the Properties of Phenolic Resin-Based Composites for Potential Applications in Abrasive Materials

    PubMed Central

    Klapiszewski, Lukasz; Jamrozik, Artur; Strzemiecka, Beata; Matykiewicz, Danuta; Voelkel, Adam; Jesionowski, Teofil

    2017-01-01

    Magnesium lignosulfonate and kraft lignin were activated by different oxidizing agents for use in phenolic resin composites used for the production of abrasive components. The physicochemical properties of the oxidized materials were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic mechanical-thermal analysis (DMTA) and inverse gas chromatography (IGC). The homogeneity of the model abrasive composites containing the studied products was assessed based on observations obtained using a scanning electron microscope (SEM). FTIR and XPS analysis of the oxidized products indicated that the activation process leads mainly to the formation of carbonyl groups. The IGC technique was used to assess changes in the surface energy and the acid–base properties of the studied biopolymers. The changes in the acid–base properties suggest that more groups acting as electron donors appear on the oxidized surface of the materials. DMTA studies showed that the model composites with 5% magnesium lignosulfonate oxidized by H2O2 had the best thermomechanical properties. Based on the results it was possible to propose a hypothetical mechanism of the oxidation of the natural polymers. The use of such oxidized products may improve the thermomechanical properties of abrasive articles. PMID:28594358

  5. Magnesium in disease

    PubMed Central

    Wanner, Christoph

    2012-01-01

    Although the following text will focus on magnesium in disease, its role in healthy subjects during physical exercise when used as a supplement to enhance performance is also noteworthy. Low serum magnesium levels are associated with metabolic syndrome, Type 2 diabetes mellitus (T2DM) and hypertension; consequently, some individuals benefit from magnesium supplementation: increasing magnesium consumption appears to prevent high blood pressure, and higher serum magnesium levels are associated with a lower risk of developing a metabolic syndrome. There are, however, conflicting study results regarding magnesium administration with myocardial infarction with and without reperfusion therapy. There was a long controversy as to whether or not magnesium should be given as a first-line medication. As the most recent trials have not shown any difference in outcome, intravenous magnesium cannot be recommended in patients with myocardial infarction today. However, magnesium has its indication in patients with torsade de pointes and has been given successfully to patients with digoxin-induced arrhythmia or life-threatening ventricular arrhythmias. Magnesium sulphate as an intravenous infusion also has an important established therapeutic role in pregnant women with pre-eclampsia as it decreases the risk of eclamptic seizures by half compared with placebo. PMID:26069818

  6. Superplasticity in Thermomechanically Processed High Magnesium Aluminum-Magnesium Alloys.

    DTIC Science & Technology

    1984-03-01

    California DTIC EECTE JL I 1984 THESIS SUPERPLASTICITY IN THERMOMECHANICALLY PROCESSED HIGH MAGNESIUM ALUMINUM-MAGNESIUM ALLOYS C:L by CD) John J. Becker...High Magnesium Aluminum- March 1984 Magnesium Alloys S. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(@) S. CONTRACT OR GRANT NUMBER(&) John J. Becker 9...magnesium, aluminum-magnesium alloys were investigated. The thermomechanical processing itself included warm rolling at 300°C to 94% reduction

  7. Magnesium in pregnancy.

    PubMed

    Dalton, Lynne M; Ní Fhloinn, Deirdre M; Gaydadzhieva, Gergana T; Mazurkiewicz, Ola M; Leeson, Heather; Wright, Ciara P

    2016-09-01

    Magnesium deficiency is prevalent in women of childbearing age in both developing and developed countries. The need for magnesium increases during pregnancy, and the majority of pregnant women likely do not meet this increased need. Magnesium deficiency or insufficiency during pregnancy may pose a health risk for both the mother and the newborn, with implications that may extend into adulthood of the offspring. The measurement of serum magnesium is the most widely used method for determining magnesium levels, but it has significant limitations that have both hindered the assessment of deficiency and affected the reliability of studies in pregnant women. Thus far, limited studies have suggested links between magnesium inadequacy and certain conditions in pregnancy associated with high mortality and morbidity, such as gestational diabetes, preterm labor, preeclampsia, and small for gestational age or intrauterine growth restriction. This review provides recommendations for further study and improved testing using measurement of red cell magnesium. Pregnant women should be counseled to increase their intake of magnesium-rich foods such as nuts, seeds, beans, and leafy greens and/or to supplement with magnesium at a safe level. © The Author(s) 2016. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. The Magnesium Branch of the Tetrapyrrole Biosynthetic Pathway

    SciTech Connect

    Beale, S. I.

    2004-05-11

    It should be noted that the focus of the research changed somewhat during the course of the current award. The initial focus is indicated by the title of the current grant, ''The Magnesium Branch of the Chlorophyll Biosynthetic Pathway''. During the current grant period, Dr. Robert Willows, a postdoctoral associate, joined the faculty of McQuarie University in Australia. When he left my lab, we decided that he should independently pursue research on structure/function relationships in Mg chelatase and that our laboratories would collaborate on regulatory studies of this enzyme. Also, during the current award period, I began collaborating with Dr. Ariane Atteia and Mr. Robert van Lis, who were at the time located at the Autonomous University of Mexico. Dr. Atteia has since joined my laboratory and Mr. van Lis will also do so when he obtains his Ph.D. in the near future. These individuals bring to the laboratory their interests and expertise in the respiratory components of Chlamydomonas and their desire to become experts in tetrapyrrole metabolism. Recently, in a collaboration with Dr. David Bollivar, a former postdoctoral associate who is now at Illinois Wesleyan University, and Dr. Caroline Walker, who was at Clemson University but has since left this research area, we recently made a major breakthrough on the oxygen-independent cyclase reaction, which has now become an important component of the current proposal. Finally, our research on phycobilin biosynthesis in Synechucystis has revealed that this organism can grow at very low oxygen concentrations and its genome contains several genes that may encode for enzymes that catalyze alternative oxygen-independent reactions for tetrapyrrole biosynthesis, so characterizing the genes, their enzymes, and regulation of expression have also become parts of the current proposal.

  9. On the effect of food magnesium level on the activity of BASP, ALAT, ASAT and LD in pig serum.

    PubMed

    Nuoranne, P

    1978-02-01

    Studies were made to investigate the effect of food Mg level on ALAT, ASAT, LD and BASP values in pigs. The following conclusions were drawn:--a high food Mg level (0.31% in ordinary pig food) can cause an increase in serum BASP values.--leg weakness, at the primary stage, is hardly caused by disturbances in bone.--an ordinary diet low in Mg may cause an abnormal rise in ALAT values in pigs.--when feeding pigs on an ordinary diet, pigs may suffer from Mg deficiency despite the fact that the food Mg content is distinctly higher than that recommended by international norms for feeding.--a prompt lowering of food Mg level can cause a manifest increase in ASAT, LD and BASP values within 2 to 3 days in pigs. Heart and liver injuries caused by low Mg diets and the individual ability of pits to utilize magnesium were discussed.

  10. Magnesium in obstetrics.

    PubMed

    James, M F M

    2010-06-01

    Magnesium is a critical physiological ion, and magnesium deficiency might contribute to the development of pre-eclampsia, to impaired neonatal development and to metabolic problems extending into adult life. Pharmacologically, magnesium is a calcium antagonist with substantial vasodilator properties but without myocardial depression. Cardiac output usually increases following magnesium administration, compensating for the vasodilatation and minimising hypotension. Neurologically, the inhibition of calcium channels and antagonism of the N-methyl-d-aspartic acid (NMDA) receptor raises the possibility of neuronal protection, and magnesium administration to women with premature labour may decrease the incidence of cerebral palsy. It is the first-line anticonvulsant for the management of pre-eclampsia and eclampsia, and it should be administered to all patients with severe pre-eclampsia or eclampsia. Magnesium is a moderate tocolytic but the evidence for its effectiveness remains disputed. The side effects of magnesium therapy are generally mild but the major hazard of magnesium therapy is neuromuscular weakness. 2009 Elsevier Ltd. All rights reserved.

  11. Oxalate metabolism in magnesium-deficient rats.

    PubMed

    Rattan, V; Thind, S K; Jethi, R K; Sidhu, H; Nath, R

    1993-06-01

    Male weanling rats were maintained on magnesium-deficient diet for 30 d and compared with pair-fed control rats fed magnesium-supplemented diet. Magnesium deficiency led to slow growth and finally to a significant decrease in body weight (P < 0.001) accompanied by a significant hypomagnesaemia, hypomagnesuria and hyperoxaluria (P < 0.001 in each case) in experimental rats as compared to the control rats. Magnesium deficiency altered the glyoxylate metabolism in the liver and kidney mitochondria by significantly decreasing glyoxylate oxidation (by 26 per cent in liver and 17 per cent in kidney) and activity of alpha-ketoglutarate:glyoxylate carboligase enzyme (by 35 per cent in liver and 27 per cent in kidney) in the experimental animals. A significant increase in the specific activities of glycolic acid oxidase (P < 0.001) and glycolic acid dehydrogenase (P < 0.01) and a significant decrease in alanine transaminase (P < 0.01) was also observed in magnesium-deficient rats. No change in liver and kidney lactate dehydrogenase was observed. Thus magnesium deficiency in rats leads to accumulation of glyoxylate in the tissues, a part of which is converted into oxalate, thereby promoting hyperoxaluria.

  12. Parenteral magnesium tolerance testing in the evaluation of magnesium deficiency.

    PubMed

    Ryzen, E; Elbaum, N; Singer, F R; Rude, R K

    1985-01-01

    Magnesium deficiency is a common clinical condition, frequently present even with normal serum magnesium (S-Mg) concentrations. We have studied retention of a low-dose (0.2 mEq/kg lean body weight), intravenously administered magnesium load in 6 hypomagnesemic patients and 18 normomagnesemic alcoholics as compared with 16 normal subjects. Both normomagnesemic and hypomagnesemic subjects retained significantly greater amounts of the administered magnesium than did the normal subjects. In patients who were restudied following parenteral magnesium repletion, retention of the magnesium load normalized. We conclude that increased retention of a magnesium load is a more sensitive index of magnesium deficiency than is the S-Mg concentration, and suggest that low-dose magnesium tolerance testing be used more frequently as a clinical tool in the evaluation of states of normomagnesemic magnesium deficiency.

  13. Transport of Magnesium by a Bacterial Nramp-Related Gene

    PubMed Central

    Rodionov, Dmitry A.; Freedman, Benjamin G.; Senger, Ryan S.; Winkler, Wade C.

    2014-01-01

    Magnesium is an essential divalent metal that serves many cellular functions. While most divalent cations are maintained at relatively low intracellular concentrations, magnesium is maintained at a higher level (∼0.5–2.0 mM). Three families of transport proteins were previously identified for magnesium import: CorA, MgtE, and MgtA/MgtB P-type ATPases. In the current study, we find that expression of a bacterial protein unrelated to these transporters can fully restore growth to a bacterial mutant that lacks known magnesium transporters, suggesting it is a new importer for magnesium. We demonstrate that this transport activity is likely to be specific rather than resulting from substrate promiscuity because the proteins are incapable of manganese import. This magnesium transport protein is distantly related to the Nramp family of proteins, which have been shown to transport divalent cations but have never been shown to recognize magnesium. We also find gene expression of the new magnesium transporter to be controlled by a magnesium-sensing riboswitch. Importantly, we find additional examples of riboswitch-regulated homologues, suggesting that they are a frequent occurrence in bacteria. Therefore, our aggregate data discover a new and perhaps broadly important path for magnesium import and highlight how identification of riboswitch RNAs can help shed light on new, and sometimes unexpected, functions of their downstream genes. PMID:24968120

  14. Transport of magnesium by a bacterial Nramp-related gene.

    PubMed

    Shin, Jung-Ho; Wakeman, Catherine A; Goodson, Jonathan R; Rodionov, Dmitry A; Freedman, Benjamin G; Senger, Ryan S; Winkler, Wade C

    2014-06-01

    Magnesium is an essential divalent metal that serves many cellular functions. While most divalent cations are maintained at relatively low intracellular concentrations, magnesium is maintained at a higher level (∼0.5-2.0 mM). Three families of transport proteins were previously identified for magnesium import: CorA, MgtE, and MgtA/MgtB P-type ATPases. In the current study, we find that expression of a bacterial protein unrelated to these transporters can fully restore growth to a bacterial mutant that lacks known magnesium transporters, suggesting it is a new importer for magnesium. We demonstrate that this transport activity is likely to be specific rather than resulting from substrate promiscuity because the proteins are incapable of manganese import. This magnesium transport protein is distantly related to the Nramp family of proteins, which have been shown to transport divalent cations but have never been shown to recognize magnesium. We also find gene expression of the new magnesium transporter to be controlled by a magnesium-sensing riboswitch. Importantly, we find additional examples of riboswitch-regulated homologues, suggesting that they are a frequent occurrence in bacteria. Therefore, our aggregate data discover a new and perhaps broadly important path for magnesium import and highlight how identification of riboswitch RNAs can help shed light on new, and sometimes unexpected, functions of their downstream genes.

  15. Neonatal effects of magnesium sulfate given to the mother.

    PubMed

    Abbassi-Ghanavati, Mina; Alexander, James M; McIntire, Donald D; Savani, Rashmin C; Leveno, Kenneth J

    2012-11-01

    Magnesium historically has been used for treatment and/or prevention of eclampsia or preterm labor. More recently, antepartum magnesium sulfate has been suggested for prevention of cerebral palsy in preterm infants. Although adverse effects and toxicity of magnesium in pregnant women are well known, the fetal-neonatal effects of magnesium are less clear. The objective of this study was to evaluate the effects of magnesium on the newborn infant. This is a retrospective cohort analysis of women who received antepartum magnesium sulfate for prevention or treatment of eclampsia. Magnesium sulfate was given intravenously beginning with a 6-g dose, followed by 2- to 3-g/h infusion. Newborn hypotonia was diagnosed if an infant exhibited less than normal tone/activity upon admission to the nursery. Between January 2000 and February 2009, a total of 6654 women with preeclampsia were treated with intravenous magnesium sulfate as described; 88 (6%) of the infants were diagnosed with hypotonia. Lower 1-minute and 5-minute Apgar scores, intubation in the delivery room, admission to special care nursery, and hypotonia were all significantly increased as maternal serum magnesium concentrations increased before birth. Several neonatal complications are significantly related to increasing concentrations of magnesium in the maternal circulation. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  16. Magnesium and depression.

    PubMed

    Serefko, Anna; Szopa, Aleksandra; Poleszak, Ewa

    2016-03-01

    Magnesium is one of the most important elements in the human body and is involved in a number of biochemical processes crucial for the proper functioning of the cardiovascular, alimentary, endocrine, and osteoarticular systems. It also plays a vital modulatory role in brain biochemistry, influencing several neurotransmission pathways associated with the development of depression. Personality changes, including apathy, depression, agitation, confusion, anxiety, and delirium are observed when there is a deficiency of this element. Rodents receiving a diet deficient in magnesium displayed depressive behaviour that was reversed by antidepressant drugs. Poor nutrition, gastrointestinal and renal diseases, insulin resistance and/or type 2 diabetes, alcoholism, stress, and certain medications may lead to magnesium deficiency. Since the extracellular concentration of magnesium ions may not reflect their intracellular level, none of the current methods of evaluating magnesium status is regarded as satisfactory. The mood-improving potential of magnesium compounds have been confirmed by the results of numerous pre-clinical and clinical studies. It seems that magnesium supplementation is well-tolerated and enhances the efficacy of conventional antidepressant treatments, and as such could be a valuable addition to the standard treatments for depression, although differences in bioavailability between inorganic and organic compounds should be taken into consideration.

  17. Method for production of magnesium

    DOEpatents

    Diaz, A.F.; Howard, J.B.; Modestino, A.J.; Peters, W.A.

    1998-07-21

    A continuous process for the production of elemental magnesium is described. Magnesium is made from magnesium oxide and a light hydrocarbon gas. In the process, a feed stream of the magnesium oxide and gas is continuously fed into a reaction zone. There the magnesium oxide and gas are reacted at a temperature of about 1400 C or greater in the reaction zone to provide a continuous product stream of reaction products, which include elemental magnesium. The product stream is continuously quenched after leaving the reaction zone, and the elemental magnesium is separated from other reaction products. 12 figs.

  18. Method for production of magnesium

    DOEpatents

    Diaz, Alexander F.; Howard, Jack B.; Modestino, Anthony J.; Peters, William A.

    1998-01-01

    A continuous process for the production of elemental magnesium is described. Magnesium is made from magnesium oxide and a light hydrocarbon gas. In the process, a feed stream of the magnesium oxide and gas is continuously fed into a reaction zone. There the magnesium oxide and gas are reacted at a temperature of about 1400.degree. C. or greater in the reaction zone to provide a continuous product stream of reaction products, which include elemental magnesium. The product stream is continuously quenched after leaving the reaction zone, and the elemental magnesium is separated from other reaction products.

  19. Struvite precipitation from urine with electrochemical magnesium dosage.

    PubMed

    Hug, Alexandra; Udert, Kai M

    2013-01-01

    When magnesium is added to source-separated urine, struvite (MgNH(4)PO(4)·6H(2)O) precipitates and phosphorus can be recovered. Up to now, magnesium salts have been used as the main source of magnesium. Struvite precipitation with these salts works well but is challenging in decentralized reactors, where high automation of the dosage and small reactor sizes are required. In this study, we investigated a novel approach for magnesium dosage: magnesium was electrochemically dissolved from a sacrificial magnesium electrode. We demonstrated that this process is technically simple and economically feasible and thus interesting for decentralized reactors. Linear voltammetry and batch experiments at different anode potentials revealed that the anode potential must be higher than -0.9 V vs. NHE (normal hydrogen electrode) to overcome the strong passivation of the anode. An anode potential of -0.6 V vs. NHE seemed to be suitable for active magnesium dissolution. For 13 subsequent cycles at this potential, we achieved an average phosphate removal rate of 3.7 mg P cm(-2) h(-1), a current density of 5.5 mA cm(-2) and a current efficiency of 118%. Some magnesium carbonate (nesquehonite) accumulated on the anode surface; as a consequence, the current density decreased slightly, but the current efficiency was not affected. The energy consumption for these experiments was 1.7 W h g P(-1). A cost comparison showed that sacrificial magnesium electrodes are competitive with easily soluble magnesium salts such as MgCl(2) and MgSO(4), but are more expensive than dosing with MgO. Energy costs for the electrochemical process were insignificant. Dosing magnesium electrochemically could thus be a worthwhile alternative to dosing magnesium salts. Due to the simple reactor and handling of magnesium, this may well be a particularly interesting approach for decentralized urine treatment.

  20. Natural killer cell activity, lymphocyte proliferation, and cytokine profile in tumor-bearing mice treated with MAPA, a magnesium aggregated polymer from Aspergillus oryzae.

    PubMed

    Justo, G Z; Durán, N; Queiroz, M L S

    2003-08-01

    The present study examined the effects of MAPA, an antitumor aggregated polymer of protein magnesium ammonium phospholinoleate-palmitoleate anhydride, isolated from Aspergillus oryzae, on concanavalin A (Con A)-induced spleen cell proliferation, cytokine production and on natural killer (NK) cell activity in Ehrlich ascites tumor-bearing mice. The Ehrlich ascites tumor (EAT) growth led to diminished mitogen-induced expansion of spleen cell populations and total NK activity. This was accompanied by striking spleen enlargement, with a marked increase in total cell counts. Moreover, a substantial enhancement in IL-10 levels, paralleled by a significant decrease in IL-2 was observed, while production of IL-4 and interferon-gamma (IFN-gamma) was not altered. Treatment of mice with 5 mg/kg MAPA for 7 days promoted spleen cell proliferation, IL-2 production and NK cell activity regardless of tumor outgrowth. In addition, MAPA treatment markedly enhanced IFN-gamma levels and reduced IL-10 production relative to EAT mice. A 35% reduction in splenomegaly with normal number of nucleated cells was also found. Altogether, our results suggest that MAPA directly and/or indirectly modulates immune cell activity, and probably disengages tumor-induced suppression of these responses. Clearly, MAPA has an impact and may delay tumor outgrowth through immunotherapeutic mechanisms.

  1. Magnesium battery disposal characteristics

    NASA Astrophysics Data System (ADS)

    Soffer, Louis; Atwater, Terrill

    1994-12-01

    This study assesses the disposal characteristics of U.S. Army procured military magnesium batteries under current Resource Conservation and Recovery Act (RCRA) hazardous waste identification regulations administered by the U.S. Environmental Protection Agency. Magnesium batteries were tested at 100, 50, 10 and 0 percent remaining state of charge. Present findings indicate that magnesium batteries with less than 50 percent remaining charge do not exceed the federal regulatory limit of 5.0 mg/L for chromium. All other RCRA contaminates were below regulatory limits at all levels of remaining charge. Assay methods, findings, disposal requirements and design implications are discussed.

  2. Castability of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Bowles, A. L.; Han, Q.; Horton, J. A.

    There is intense research effort into the development of high pressure die cast-able creep resistant magnesium alloys. One of the difficulties encountered in magnesium alloy development for creep resistance is that many additions made to improve the creep properties have reportedly resulted in alloys that are difficult to cast. It is therefore important to have an understanding of the effect of alloying elements on the castability. This paper gives a review of the state of the knowledge of the castability of magnesium alloys.

  3. Magnesium toxicosis in two horses.

    PubMed

    Henninger, R W; Horst, J

    1997-07-01

    Magnesium sulfate, a saline laxative, is often used for treatment of intestinal impactions in horses. Clinical signs of hypermagnesemia are an uncommon complication following oral administration of magnesium sulfate. Overdose of magnesium sulfate in combination with renal insufficiency, hypocalcemia, or compromise of intestinal integrity may predispose horses to magnesium toxicosis. Establishment of diuresis with fluids and IV administration of calcium may provide successful treatment of magnesium toxicosis in horses.

  4. Sodium-dependent magnesium uptake by ferret red cells.

    PubMed Central

    Flatman, P W; Smith, L M

    1991-01-01

    1. Magnesium uptake can be measured in ferret red cells incubated in media containing more than 1 mM-magnesium. Uptake is substantially increased if the sodium concentration in the medium is reduced. 2. Magnesium uptake is half-maximally activated by 0.37 mM-external magnesium when the external sodium concentration is 5 mM. Increasing the external sodium concentration increases the magnesium concentration needed to activate the system. 3. Magnesium uptake is increased by reducing the external sodium concentration. Uptake is half-maximum at sodium concentrations of 17, 22 and 62 nM when the external magnesium concentrations are 2, 5 and 10 mM respectively. 4. Replacement of external sodium with choline does not affect the membrane potential of ferret red cells over a 45 min period. 5. Magnesium uptake from media containing 5 mM-sodium is inhibited by amiloride, quinidine and imipramine. It is not affected by ouabain or bumetanide. Vanadate stimulates magnesium uptake but has no effect on magnesium efflux. 6. When cell ATP content is reduced to 19 mumol (1 cell)-1 by incubating cells for 3 h with 2-deoxyglucose, magnesium uptake falls by 50% in the presence of 5 mM-sodium and is completely abolished in the presence of 145 mM-sodium. Some of the inhibition may be due to the increase in intracellular ionized magnesium concentration ([Mg2+]i) from 0.7 to 1.0 mM which occurs under these conditions. 7. Magnesium uptake can be driven against a substantial electrochemical gradient if the external sodium concentration is reduced sufficiently. 8. These findings are discussed in terms of several possible models for magnesium transport. It is concluded that the majority of magnesium uptake observed in low-sodium media is via sodium-magnesium antiport. A small portion of uptake is through a parallel leak pathway. It is believed that the antiport is responsible for maintaining [Mg2+]i below electrochemical equilibrium in these cells at physiological external sodium concentration

  5. Magnesium for automotive applications

    SciTech Connect

    VanFleteren, R.

    1996-05-01

    Die cast magnesium parts are rapidly replacing steel and aluminum structural components in automotive applications, as design engineers seek to reduce assembly costs, raise fuel efficiency, and improve safety. Dozens of automotive components are now die cast from magnesium alloys, including seat stanchions, valve covers, steering wheels, and a variety of steering column components. Because of their excellent castability, complex magnesium die castings can sometimes consolidate several components and eliminate assembly steps. Highly ductile magnesium alloys such as AM60B (6% aluminum) and AM50A (5% aluminum) are important in helping to meet automotive industry crash-energy requirements for car seating and steering components. AZ91D (9% aluminum, 1% zinc) alloys are making removable rear seats in new minivans much easier to handle.

  6. Magnesium blood test

    MedlinePlus

    Magnesium - blood ... A blood sample is needed. ... When the needle is inserted to draw blood, some people feel slight pain. Others feel a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon ...

  7. Rechargeable Magnesium Power Cells

    NASA Technical Reports Server (NTRS)

    Koch, Victor R.; Nanjundiah, Chenniah; Orsini, Michael

    1995-01-01

    Rechargeable power cells based on magnesium anodes developed as safer alternatives to high-energy-density cells like those based on lithium and sodium anodes. At cost of some reduction in energy density, magnesium-based cells safer because less susceptible to catastrophic meltdown followed by flames and venting of toxic fumes. Other advantages include ease of handling, machining, and disposal, and relatively low cost.

  8. Interstellar magnesium abundances

    NASA Technical Reports Server (NTRS)

    Murray, M. J.; Dufton, P. L.; Hibbert, A.; York, D. G.

    1984-01-01

    An improved evaluation of the Mg II 1240 A doublet oscillator strength is used in conjunction with recently published Copernicus observations to derive accurate Mg II column densities toward 74 stars. These imply an average of 40 percent of interstellar magnesium is in the gaseous phase. Magnesium depletion is examined as a function of various interstellar extinction and density parameters, and the results are briefly discussed in terms of current depletion theories.

  9. Magnesium and cardiovascular system.

    PubMed

    Shechter, Michael

    2010-06-01

    Hypomagnesemia is common in hospitalized patients, especially in the elderly with coronary artery disease (CAD) and/or those with chronic heart failure. Hypomagnesemia is associated with an increased incidence of diabetes mellitus, metabolic syndrome, mortality rate from CAD and all causes. Magnesium supplementation improves myocardial metabolism, inhibits calcium accumulation and myocardial cell death; it improves vascular tone, peripheral vascular resistance, afterload and cardiac output, reduces cardiac arrhythmias and improves lipid metabolism. Magnesium also reduces vulnerability to oxygen-derived free radicals, improves human endothelial function and inhibits platelet function, including platelet aggregation and adhesion, which potentially gives magnesium physiologic and natural effects similar to adenosine-diphosphate inhibitors such as clopidogrel. The data regarding its use in patients with acute myocardial infarction (AMI) is conflicting. Although some previous, relatively small randomized clinical trials demonstrated a remarkable reduction in mortality when administered to relatively high risk AMI patients, two recently published large-scale randomized clinical trials (the Fourth International Study of Infarct Survival and Magnesium in Coronaries) failed to show any advantage of intravenous magnesium over placebo. Nevertheless, there are theoretical potential benefits of magnesium supplementation as a cardioprotective agent in CAD patients, as well as promising results from previous work in animal and humans. These studies are cost effective, easy to handle and are relatively free of adverse effects, which gives magnesium a role in treating CAD patients, especially high-risk groups such as CAD patients with heart failure, the elderly and hospitalized patients with hypomagnesemia. Furthermore, magnesium therapy is indicated in life-threatening ventricular arrhythmias such as Torsades de Pointes and intractable ventricular tachycardia.

  10. Effect of magnesium chloride on psychomotor activity, emotional status, and acute behavioural responses to clonidine, d-amphetamine, arecoline, nicotine, apomorphine, and L-5-hydroxytryptophan.

    PubMed

    Iezhitsa, Igor N; Spasov, Alexander A; Kharitonova, Maria V; Kravchenko, Maria S

    2011-01-01

    The beneficial effects of magnesium (Mg) salts on central manifestations of Mg deficiency are well known. Mg replacement therapy can be effective to prevent some of the serious depression-like and anxiety-related behaviour sequelae of Mg deficiency. However, few experimental studies have been undertaken on Mg-deficiency-induced behavioural changes. Even fewer studies have been carried out on acute behavioural responses to clonidine, D-amphetamine, arecoline, nicotine, apomorphine, and L-5-hydroxytryptophan (HTP), which might characterize possible neuromediator changes in Mg deficiency. The effects of correcting Mg deficiency by magnesium chloride (MgCl₂ · 6H₂O) and the combination of this salt with vitamin B₆, on the behavioural manifestations of Mg deficiency have never been described as well. The aims of this study were: to estimate effect of MgCl₂ · 6H₂O alone and in combination with vitamin B6 on acute behavioural responses to agonists or blockers of the main neurotransmitter systems in CNS, psychomotor activity and emotional status of rats fed with Mg-deficient diet for 49 days. In our study open field test has shown that in Mg-deficient rats locomotor activity and vertical activity, number of visiting and residence time in central squares were decreased significantly. In the elevated plus maze test, the number of visiting open arms and residence time of rats were significantly less as compared with the control group. In the forced swimming test, time immobile was significantly increased by 44.29% and time of swimming was decreased by 52.79% compared to control. In our study Mg-deficient rats were more sensitive to d-amphetamine-induced motor stereotypes. Mg deficiency antagonized 5-hydroxytryptophan-induced head-twitch response and arecoline-induced tremor. Supplement of MgCl₂ · 6H₂O with vitamin B₆ administered to a Mg-deficient rat increased the Mg level in plasma and erythrocytes. Furthermore, this increase was in relation to vitamin B

  11. Magnesium for Future Autos

    SciTech Connect

    Nyberg, Eric A.; Luo, Alan A.; Sadayappan, Kumar; Shi, Wenfang

    2008-10-01

    In the quest for better fuel economy and improved environmental performance, magnesium may well become a metal of choice for constructing lighter, more efficient vehicles. Magnesium is the lightest structural metal, yet it has a high strength-to-weight ratio makes it comparable to steel in many applications. The world’s automakers already use magnesium for individual components. But new alloys and processing methods are needed before the metal can become economically and technologically feasible as a major automotive structural material. This article will explore the formation, challenges and initial results of an international collaboration—the Magnesium Front End Research and Development (MFERD) project—that is leveraging the expertise and resources of Canada, China and the United States to advance the creation of magnesium-intensive vehicles. The MFERD project aims to develop the enabling technologies and knowledge base that will lead to a vehicles that are 50-60 percent lighter, equally affordable, more recyclable and of equal or better quality when compared to today’s vehicles. Databases of information also will be captured in models to enable further alloy and manufacturing process optimization. Finally, a life-cycle analysis of the magnesium used will be conducted.

  12. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, A.

    1988-01-21

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  13. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, Anton

    1988-01-01

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  14. Effects of extracellular magnesium on the differentiation and function of human osteoclasts.

    PubMed

    Wu, Lili; Luthringer, Bérengère J C; Feyerabend, Frank; Schilling, Arndt F; Willumeit, Regine

    2014-06-01

    Magnesium-based implants have been shown to influence the surrounding bone structure. In an attempt to partially reveal the cellular mechanisms involved in the remodelling of magnesium-based implants, the influence of increased extracellular magnesium content on human osteoclasts was studied. Peripheral blood mononuclear cells were driven towards an osteoclastogenesis pathway via stimulation with receptor activator of nuclear factor kappa-B ligand and macrophage colony-stimulating factor for 28 days. Concomitantly, the cultures were exposed to variable magnesium concentrations (from either magnesium chloride or magnesium extracts). Osteoclast proliferation and differentiation were evaluated based on cell metabolic activity, total protein content, tartrate-resistant acid phosphatase activity, cathepsin K and calcitonin receptor immunocytochemistry, and cellular ability to form resorption pits. While magnesium chloride first enhanced and then opposed cell proliferation and differentiation in a concentration-dependent manner (peaking between 10 and 15mM magnesium chloride), magnesium extracts (with lower magnesium contents) appeared to decrease cell metabolic activity (≈50% decrease at day 28) while increasing osteoclast activity at a lower concentration (twofold higher). Together, the results indicated that (i) variations in the in vitro extracellular magnesium concentration affect osteoclast metabolism and (ii) magnesium extracts should be used preferentially in vitro to more closely mimic the in vivo environment. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Reduced toxicological activity of cigarette smoke by the addition of ammonia magnesium phosphate to the paper of an electrically heated cigarette: subchronic inhalation toxicology.

    PubMed

    Moennikes, O; Vanscheeuwijck, P M; Friedrichs, B; Anskeit, E; Patskan, G J

    2008-05-01

    Cigarette smoke is a complex chemical mixture that causes a variety of diseases, such as lung cancer. With the electrically heated cigarette smoking system (EHCSS), temperatures are applied to the tobacco below those found in conventional cigarettes, resulting in less combustion, reduced yields of some smoke constituents, and decreased activity in some standard toxicological tests. The first generation of electrically heated cigarettes (EHC) also resulted in increased formaldehyde yields; therefore, a second generation of EHC was developed with ammonium magnesium phosphate (AMP) in the cigarette paper in part to address this increase. The toxicological activity of mainstream smoke from these two generations of EHC and of a conventional reference cigarette was investigated in two studies in rats: a standard 90-day inhalation toxicity study and a 35-day inhalation study focusing on lung inflammation. Many of the typical smoke exposure-related changes were found to be less pronounced after exposure to smoke from the second-generation EHC with AMP than to smoke from the first-generation EHC or the conventional reference cigarette, when compared on a particulate matter or nicotine basis. Differences between the EHC without AMP and the conventional reference cigarette were not as prominent. Overall, AMP incorporated in the EHC cigarette paper reduced the inhalation toxicity of the EHCSS more than expected based on the observed reduction in aldehyde yields.

  16. Absence of correlation between magnesium and riboflavin status.

    PubMed

    Eisinger, J; Clairet, D; Brue, F; Ayavou, T

    1993-06-01

    Erythrocyte magnesium and glutathione reductase activity coefficient (EGR-AC), reflecting vitamin B-2 status, were assessed in 11 athletes, 20 patients with fibromyalgia, 18 patients with hypothyroidism, and 13 controls. No correlation was demonstrated between erythrocyte magnesium and EGR-AC.

  17. Magnesium alloy ingots: Chemical and metallographic analyses

    NASA Astrophysics Data System (ADS)

    Tartaglia, John M.; Swartz, Robert E.; Bentz, Rodney L.; Howard, Jane H.

    2001-11-01

    The quality of a magnesium die casting is likely dependent on the quality of the feed stockingot material. Therefore, both Daimler-Chrysler and General Motors have established quality assurance measures that include analysis of magnesium ingots. These processes include chemical analysis, corrosion testing, fast neutron activation analysis, and metallography. Optical emission spectroscopy, inductively coupled plasma spectroscopy, and gravimetric analysis are several methods for determining the chemical composition of the material. Fast neutron activation analysis, image analysis and energy dispersive X-ray spectroscopy are used to quantify ingot cleanliness. These experimental techniques are described and discussed in this paper, and example case studies are presented for illustration.

  18. Blood compatibility of magnesium and its alloys.

    PubMed

    Feyerabend, Frank; Wendel, Hans-Peter; Mihailova, Boriana; Heidrich, Stefanie; Agha, Nezha Ahmad; Bismayer, Ulrich; Willumeit-Römer, Regine

    2015-10-01

    Blood compatibility analysis in the field of biomaterials is a highly controversial topic. Especially for degradable materials like magnesium and its alloys no established test methods are available. The purpose of this study was to apply advanced test methodology for the analysis of degrading materials to get a mechanistic insight into the corrosion process in contact with human blood and plasma. Pure magnesium and two magnesium alloys were analysed in a modified Chandler-Loop setup. Standard clinical parameters were determined, and a thorough analysis of the resulting implant surface chemistry was performed. The contact of the materials to blood evoked an accelerated inflammatory and cell-induced osteoconductive reaction. Corrosion products formed indicate a more realistic, in vivo like situation. The active regulation of corrosion mechanisms of magnesium alloys by different cell types should be more in the focus of research to bridge the gap between in vitro and in vivo observations and to understand the mechanism of action. This in turn could lead to a better acceptance of these materials for implant applications. The presented study deals with the first mechanistic insights during whole human blood contact and its influence on a degrading magnesium-based biomaterial. The combination of clinical parameters and corrosion layer analysis has been performed for the first time. It could be of interest due to the intended use of magnesium-based stents and for orthopaedic applications for clinical applications. An interest for the readers of Acta Biomaterialia may be given, as one of the first clinically approved magnesium-based devices is a wound-closure device, which is in direct contact with blood. Moreover, for orthopaedic applications also blood contact is of high interest. Although this is not the focus of the manuscript, it could help to rise awareness for potential future applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All

  19. The Association Between Effective Dose of Magnesium and Mild Compulsive Exercise on Spatial Learning, Memory, and Motor Activity of Adult Male Rats.

    PubMed

    Hajizade Ghonsulakandi, Shahnaz; Sheikh, Mahmuod; Dehghan Shasaltaneh, Marzieh; Chopani, Samira; Naghdi, Nasser

    2017-01-25

    One of the most important survival mechanisms is learning and memory processes. To emphasize the role of physical exercises and magnesium (Mg) in improvement of cognitive performance, we planned to investigate the effect of Mg and mild compulsive exercise on spatial learning and memory of adult male rats. Accordingly, we divided male Wistar rats into four groups: (I) control, (II) Mg treatment, (III) exercise, and (IV) Mg-exercise in the different dosages of Mg (0.5, 1, 1.5, and 2 mmol/kbw) were injected in the form of gavage during 1 week. Also, 1-week mild running on treadmill was used for exercise treatment. The Morris water maze (MWM) test and open field tool were used to evaluate spatial learning, memory, and motor activity, respectively. Our results clearly showed that 1 mmol/kbw Mg was applied as an effective dosage. Strikingly, 1-week mild exercise on treadmill had no significant effect on spatial motor activity, learning, and memory. Feeding 1 mmol/kbw Mg for a week showed a significant difference in learning and exploration stages. Compared to control animals, these results reveal exercise and Mg simultaneously had effect on learning and reminding. As a consequence, although mild exercise had no effect on motor activity and memory, Mg intake improved spatial learning, memory, and locomotor activity. The Mg feeding could be a promising supplemental treatment in the neurodegenerative disease. It is worthwhile to mention consumption of Mg leads to enhancement of memory, so animals find the hidden platform with the highest velocity.

  20. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium phosphate. 184.1434 Section 184.1434 Food... Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic (MgHPO4·3H2O...

  1. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic (MgHPO4·3H2O, CAS Reg. No. 7782-0975...

  2. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... Listing of Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic...

  3. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... Listing of Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic...

  4. 21 CFR 184.1434 - Magnesium phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium phosphate. 184.1434 Section 184.1434... Listing of Specific Substances Affirmed as GRAS § 184.1434 Magnesium phosphate. (a) Magnesium phosphate includes both magnesium phosphate, dibasic, and magnesium phosphate, tribasic. Magnesium phosphate, dibasic...

  5. Uniform dispersion of cobalt nanoparticles over nonporous TiO2 with low activation energy for magnesium sulfate recovery in a novel magnesia-based desulfurization process.

    PubMed

    Wang, Lidong; Qi, Tieyue; Wang, Juan; Zhang, Shihan; Xiao, Huining; Ma, Yongliang

    2017-09-08

    The forced oxidation of magnesium sulfite (MgSO3) aims to not only reclaim the by-product in the magnesia desulfurization, but also lower the risk of secondary pollution. The non-porous titanium dioxide nanoparticle was used as a support to prepare the cobalt catalyst (Co-TiO2) in order to expedite the oxidation rate. This fabricated Co-TiO2 was characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and energy dispersive spectroscopy (EDS) to figure out its catalytic mechanism. The results revealed that the cobalt nanoparticles were uniformly dispersed on the surface of the TiO2 in forms of Co3O4 and Co2O3. The kinetics of the MgSO3 oxidation catalyzed by the prepared Co-TiO2 was investigated in a bubbling tank reactor, indicating that the oxidation rate was dependent on the catalyst concentration, oxygen partial pressure, pH value, and the reaction temperature. Compared with the reported porous catalyst (Co-CNTs), the activation energy with the Co-TiO2 (17.29kJmol(-1)) decreased by 50.9%, resulting in a good catalytic performance in sulfite oxidation. The findings will help advance the industrial application of the novel magnesia desulfurization process. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Magnesium inhibition of calcite dissolution kinetics

    SciTech Connect

    Arvidson, Rolf S.; Collier, Martin; Davis, Kevin J.; Vinson, Michael D.; Amonette, James E.; Luttge, Andreas

    2006-02-01

    We present evidence of inhibition of calcite dissolution by dissolved magnesium through direct observations of the (104) surface using atomic force microscopy (AFM) and vertical scanning interferometry (VSI). Far from equilibrium, the pattern of magnesium inhibition is dependent on solution composition and specific to surface step geometry. In CO2-free solutions (pH 8.8), dissolved magnesium brings about little inhibition even at concentrations of 0.8 x 10-3 molal. At the same pH, magnesium concentrations of less than 0.05 x 10-3 molal in carbonate-buffered solutions generate significant inhibition, although no changes in surface and etch pit morphology are observed. As concentrations exceed magnesite saturation, the dissolution rate shows little additional decrease; however, selective pinning of step edges results in unique etch-pit profiles, seen in both AFM and VSI datasets. Despite the decreases in step velocity, magnesium addition in carbonated solutions also appears to activate the surface by increasing the nucleation rate of new defects. These relationships suggest that the modest depression of the bulk rate measured by VSI reflects a balance between competing reaction mechanisms that simultaneously depress the rate through selective inhibition of step movement, but also enhance reactivity on terraces by lowering the energy barrier to new etch-pit formation.

  7. Improvement of hydrogen storage properties of magnesium alloys by cold rolling and forging

    NASA Astrophysics Data System (ADS)

    Huot, Jacques; Amira, Sofiene; Lang, Julien; Skryabina, Nataliya; Fruchart, Daniel

    2014-08-01

    In this talk we show that cold rolling (CR) could be used to enhance hydrogen sorption properties of magnesium and magnesium alloys. In particular, cold rolling could reduce the first hydrogenation time, the so-called activation. Pure magnesium, commercial AZ91D alloy, and an experimental creep resistant magnesium alloy MRI153 in the as-cast and die-cast states were investigated. We found that both MRI and AZ91 alloys present faster activation kinetic than pure magnesium. This could be explained by the texture, higher number of defects, and nanostructure in CR materials but also precipitates at the grain boundaries. The effect of filing was also investigated.

  8. A Quick Reference on Magnesium.

    PubMed

    Bateman, Shane W

    2017-03-01

    This article serves as a quick reference on the distribution, handling, and supplementation of magnesium. It also lists the manifestations and causes of magnesium deficit and provides criteria for the diagnosis of a magnesium deficit. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Magnesium Metabolism and its Disorders

    PubMed Central

    Swaminathan, R

    2003-01-01

    Magnesium is the fourth most abundant cation in the body and plays an important physiological role in many of its functions. Magnesium balance is maintained by renal regulation of magnesium reabsorption. The exact mechanism of the renal regulation is not fully understood. Magnesium deficiency is a common problem in hospital patients, with a prevalence of about 10%. There are no readily available and easy methods to assess magnesium status. Serum magnesium and the magnesium tolerance test are the most widely used. Measurement of ionised magnesium may become more widely available with the availability of ion selective electrodes. Magnesium deficiency and hypomagnesaemia can result from a variety of causes including gastrointestinal and renal losses. Magnesium deficiency can cause a wide variety of features including hypocalcaemia, hypokalaemia and cardiac and neurological manifestations. Chronic low magnesium state has been associated with a number of chronic diseases including diabetes, hypertension, coronary heart disease, and osteoporosis. The use of magnesium as a therapeutic agent in asthma, myocardial infarction, and pre-eclampsia is also discussed. Hypermagnesaemia is less frequent than hypomagnesaemia and results from failure of excretion or increased intake. Hypermagnesaemia can lead to hypotension and other cardiovascular effects as well as neuromuscular manifestations. Causes and management of hypermagnesaemia are discussed. PMID:18568054

  10. Porphyrin Binding to Gun4 Protein, Facilitated by a Flexible Loop, Controls Metabolite Flow through the Chlorophyll Biosynthetic Pathway.

    PubMed

    Kopečná, Jana; Cabeza de Vaca, Israel; Adams, Nathan B P; Davison, Paul A; Brindley, Amanda A; Hunter, C Neil; Guallar, Victor; Sobotka, Roman

    2015-11-20

    In oxygenic phototrophs, chlorophylls, hemes, and bilins are synthesized by a common branched pathway. Given the phototoxic nature of tetrapyrroles, this pathway must be tightly regulated, and an important regulatory role is attributed to magnesium chelatase enzyme at the branching between the heme and chlorophyll pathway. Gun4 is a porphyrin-binding protein known to stimulate in vitro the magnesium chelatase activity, but how the Gun4-porphyrin complex acts in the cell was unknown. To address this issue, we first performed simulations to determine the porphyrin-docking mechanism to the cyanobacterial Gun4 structure. After correcting crystallographic loop contacts, we determined the binding site for magnesium protoporphyrin IX. Molecular modeling revealed that the orientation of α6/α7 loop is critical for the binding, and the magnesium ion held within the porphyrin is coordinated by Asn-211 residue. We also identified the basis for stronger binding in the Gun4-1 variant and for weaker binding in the W192A mutant. The W192A-Gun4 was further characterized in magnesium chelatase assay showing that tight porphyrin binding in Gun4 facilitates its interaction with the magnesium chelatase ChlH subunit. Finally, we introduced the W192A mutation into cells and show that the Gun4-porphyrin complex is important for the accumulation of ChlH and for channeling metabolites into the chlorophyll biosynthetic pathway.

  11. Porphyrin Binding to Gun4 Protein, Facilitated by a Flexible Loop, Controls Metabolite Flow through the Chlorophyll Biosynthetic Pathway*

    PubMed Central

    Kopečná, Jana; Cabeza de Vaca, Israel; Adams, Nathan B. P.; Davison, Paul A.; Brindley, Amanda A.; Hunter, C. Neil; Guallar, Victor; Sobotka, Roman

    2015-01-01

    In oxygenic phototrophs, chlorophylls, hemes, and bilins are synthesized by a common branched pathway. Given the phototoxic nature of tetrapyrroles, this pathway must be tightly regulated, and an important regulatory role is attributed to magnesium chelatase enzyme at the branching between the heme and chlorophyll pathway. Gun4 is a porphyrin-binding protein known to stimulate in vitro the magnesium chelatase activity, but how the Gun4-porphyrin complex acts in the cell was unknown. To address this issue, we first performed simulations to determine the porphyrin-docking mechanism to the cyanobacterial Gun4 structure. After correcting crystallographic loop contacts, we determined the binding site for magnesium protoporphyrin IX. Molecular modeling revealed that the orientation of α6/α7 loop is critical for the binding, and the magnesium ion held within the porphyrin is coordinated by Asn-211 residue. We also identified the basis for stronger binding in the Gun4-1 variant and for weaker binding in the W192A mutant. The W192A-Gun4 was further characterized in magnesium chelatase assay showing that tight porphyrin binding in Gun4 facilitates its interaction with the magnesium chelatase ChlH subunit. Finally, we introduced the W192A mutation into cells and show that the Gun4-porphyrin complex is important for the accumulation of ChlH and for channeling metabolites into the chlorophyll biosynthetic pathway. PMID:26446792

  12. The influence of magnesium on the activity of some enzymes (AST, ALT, ALP) and lead content in some tissues.

    PubMed

    Todorovic, Tatjana; Vujanovic, Dragana

    2002-12-01

    Many authors in different studies have reported the antagonism between Mg and Pb. Our previous results suggested that oral Mg treatment have better effect on investigation biochemical parameters (protoporphyrins, aminolevulinic acid--ALA and d-aminolevulinic dehydratase ALA-D) used in evaluating Pb intoxication, then CaNa2EDTA, chelation agents, currently used in therapy of Pb intoxication. The toxic effect of Pb induced considerably modifies the activity of many other enzymes. In this work we have examined the influence of Mg (as alternative therapy of Pb poisoning) on enzymes activity--biochemical markers for general health conditions--aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in condition of lead intoxication. Many studies showed disturbances of activity ALT, AST and ALP. The aim of this study was to confirm positive effects of Mg intake in condition of such intoxication at the level on activity of investigated enzymes. The experiment was performed on 45 male Wister rats, divided in three groups. I--control group; II--group treated daily for 30 days with 100 mg Pb, per kg body weight and next 60 without Pb treatment (spontaneous detoxication); III group--the same treatment as II group for the first 30 days, but next 60 days rats were treated orally with 40 mg Mg/kg body weight. Activity of AST and ALT was significant increased in condition of Pb poisoning, but ALP activity was significant reduced. Influence of excessive oral Mg treatment was positive: decrease of AST activity and ALT activity, which was probably in correlation with significant elimination of Pb from liver and increase of ALT enzyme activity at the normal level.

  13. Magnesium in cystic fibrosis--Systematic review of the literature.

    PubMed

    Santi, Maristella; Milani, Gregorio P; Simonetti, Giacomo D; Fossali, Emilio F; Bianchetti, Mario G; Lava, Sebastiano A G

    2016-02-01

    The metabolism of sodium, potassium, and chloride and the acid-base balance are sometimes altered in cystic fibrosis. Textbooks and reviews only marginally address the homeostasis of magnesium in cystic fibrosis. We performed a search of the Medical Subject Headings terms (cystic fibrosis OR mucoviscidosis) AND (magnesium OR hypomagnes[a]emia) in the US National Library of Medicine and Excerpta Medica databases. We identified 25 reports dealing with magnesium and cystic fibrosis. The results of the review may be summarized as follows. First, hypomagnesemia affects more than half of the cystic fibrosis patients with advanced disease; second, magnesemia, which is normally age-independent, relevantly decreases with age in cystic fibrosis; third, aminoglycoside antimicrobials frequently induce both acute and chronic renal magnesium-wasting; fourth, sweat magnesium concentration was normal in cystic fibrosis patients; fifth, limited data suggest the existence of an impaired intestinal magnesium balance. Finally, stimulating observations suggest that magnesium supplements might achieve an improvement in respiratory muscle strength and mucolytic activity of both recombinant and endogenous deoxyribonuclease. The first comprehensive review of the literature confirms that, despite being one of the most prevalent minerals in the body, the importance of magnesium in cystic fibrosis is largely overlooked. In these patients, hypomagnesemia should be sought once a year. Furthermore, the potential of supplementation with this cation deserves more attention. © 2015 Wiley Periodicals, Inc.

  14. Magnesium Research and Technology Development

    SciTech Connect

    Nyberg, Eric A.; Joost, William; Smith, Mark T.

    2009-12-30

    The Magnesium Research and Technical Development (MR&TD) project supports efforts to increase using magnesium in automotive applications, including improving technology, lowering costs and increasing the knowledge needed to enable alloy and manufacturing process optimization. MR&TD supports the U.S. Department of Energy (DOE)/United States Automotive Materials Partnership (USAMP) Magnesium Front End Research and Development (MFERD) project in collaboration with China and Canada. The MR&TD projects also maintains the magnesium bibliographic database at magnesium.pnl.gov.

  15. Serum ionized versus total magnesium in patients with intestinal or liver disease.

    PubMed

    Saha, H; Harmoinen, A; Karvonen, A L; Mustonen, J; Pasternack, A

    1998-09-01

    In serum, magnesium exists in three fractions: protein-bound, complex-bound and free ionized form. Only the free ionized fraction is biologically active. Until recently, only the measurement of serum total magnesium has been in clinical use. Now, commercially available instruments using new ion-selective electrodes for Mg++ have made possible the reliable measurement of serum ionized magnesium in clinical practice. For the measurement of serum ionized magnesium we used a magnesium-selective electrode installed in a six-channel electrolyte analyzer. We compared the use of ionized versus total magnesium measurement in 52 patients with intestinal disease, 54 with liver disease, and in 75 healthy control subjects. In the patients with alcoholic liver disease both serum ionized and total magnesium were lower, and in those with inflammatory bowel disease slightly higher than in control subjects. The correlation coefficient between serum ionized and total magnesium was r=0.87 (p<0.001) in the patients, and r=0.75 (p<0.001) in the controls. In the patient group the fraction of ionized magnesium in the total was negatively related to the serum albumin level (r=-0.41, p<0.001). Serum total magnesium was below the reference range in 30 out of 150 measurements, serum ionized magnesium in only 9 out of 150 measurements, respectively. Thus, 21 cases with low total but normal ionized magnesium (two thirds of hypomagnesemia according to serum total magnesium) were false positive. Total magnesium measurement may overestimate the incidence of hypomagnesemia when significant hypoalbuminemia is present. Measurement of serum ionized magnesium instead of total magnesium may therefore be of advantage in evaluating patients with hypoalbuminemia and when hypomagnesemia is expected.

  16. Grain Refinement of Magnesium

    NASA Astrophysics Data System (ADS)

    Lee, Y. C.; Dahle, A. K.; StJohn, D. H.

    Grain formation during solidification of magnesium and Mg-Al alloys has been studied with a focus on grain refinement mechanisms, solute and particle effects. The variation in grain size with increased aluminium content in hypoeutectic Mg-Al alloys showed a continuous decrease in grain size up to 5 wt% Al, and a stabilisation at higher Al contents (above 5 wt%). Strontium additions to both low- and high-aluminium content magnesium alloys showed that Sr had a significant grain refining effect in low-aluminium containing alloys. However, strontium had a negligible effect on grain size in the Mg-9Al alloy. Additions of Zr, Si, or Ca to pure magnesium produced significant grain refinement, probably because these elements have high growth restriction effects during solidification. An attempt was made to identify the grain refinement effect of particles added directly to the melt that are considered to be powerful nucleants in Al based alloys (TiC) and in Mg based alloys (AlN, Al4C3). Most of these particles produced grain refinement, probably because of enhanced nucleation due to the small lattice disregistry between their crystal structures and that of magnesium. However, it is not clear whether the grain refining mechanism of the effective particles was catalysis of primary crystal nucleation or simply restriction of crystal growth during solidification.

  17. Magnesium fluoride recovery method

    SciTech Connect

    Gay, R.L.; McKenzie, D.E.

    1989-10-17

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag formed in the production of metallic uranium by the reduction of depleted uranium tetrafluoride with metallic magnesium in a retort wherein the slag contains the free metals magnesium and uranium and also oxides and fluorides of the metals. The slag having a radioactivity level of at least about 7,000 rhoCi/gm. The method comprises the steps of: grinding the slag to a median particle size of about 200 microns; contacting the ground slag in a reaction zone with an acid having a strength of from about 0.5 to 1.5 N for a time of from about 4 to about 20 hours in the presence of a catalytic amount of iron; removing the liquid product; treating the particulate solid product; repeating the last two steps at least one more time to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 rhoCi/gm.

  18. Magnesium fluoride recovery method

    SciTech Connect

    Gay, R.L.; McKenzie, D.E.

    1989-10-17

    This patent describes a method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag formed in the production of metallic uranium by the reduction of depleted uranium tetrafluoride with metallic magnesium in a retort wherein the slag contains the free metals magnesium and uranium and also oxides and fluorides of the metals, the slag having a radioactivity level of at least about 7,000 pCi/gm. The method comprises: grinding the slag to a median particle size of about 200 microns; contacting the ground slag in a reaction zone with an acid having a strength of from about 0.5 to 1.5 N for a time of from about 4 to about 20 hours in the presence of a catalytic amount of iron, the reaction zone being maintained at a temperature within the range of from about 60{degrees} to 90{degrees} C. and the weight of ratio of slag to acid being within the range of from about 1:2 to 1:6 to produce a liquid product and a particulate solid product; removing the liquid product; treating the particulate solid product; and repeating steps at least one more time to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 pCi/gm.

  19. Do diuretics cause magnesium deficiency?

    PubMed Central

    Davies, D L; Fraser, R

    1993-01-01

    1. Controlled trials, of which there are few, do not substantiate claims that diuretics play a role in causing magnesium deficiency. Consequently, the vast majority of patients taking conventional doses of thiazide diuretics (i.e. bendrofluazide 2.5 mg day-1 or equivalent) do not need magnesium supplements. On balance, potassium-sparing diuretics tend to increase serum and intracellular magnesium content; this should not be taken as evidence of prior magnesium deficiency. It remains theoretically possible that large doses of loop diuretics given more than once daily for long periods could induce negative magnesium balance and magnesium deficiency. However, it has been difficult to run appropriately controlled trials in conditions where such therapy is needed (i.e. heart failure) and until more reliable information becomes available no absolute recommendation can be made. 2. Methods for the measurement of intracellular free magnesium levels are now available and are more relevant to the assessment of magnesium deficiency than total intracellular magnesium content; the complex relationship between intracellular free and total magnesium content remains to be defined. Future work involving the effect of diuretics on intracellular free magnesium measurements should make every attempt to avoid the errors of trial design and multiple publication that litter current and past literature. PMID:8373706

  20. Preparation and hydriding behavior of magnesium metal clusters formed in low-temperature cocondensation: application of magnesium for hydrogen storage

    SciTech Connect

    Imamura, H.; Nobunaga, T.; Kawahigashi, M.; Tsuchiya, S.

    1984-08-01

    Magnesium metal clusters formed in low-temperature matrices were investigated with a view to forming the metal hydride. In practice, magnesium readily absorbed large amounts of hydrogen under more moderate conditions (P/sub H/sub 2// = 460 torr, T = 200-250/sup 0/C) when it had been transformed into tetrahydrofuran- (THF-) solvated small particles formed by the cocondensation reaction of magnesium atoms with THF molecules at -196/sup 0/C. To elucidate the characteristics of hydrogen sorption of Mg-THF, a comparative study with pure magnesium powder was carried out. It is believed from the H/sub 2/-D/sub 2/ isotope scrambling measurements that the high activity of the present Mg-THF system for hydrogen absorption is due to a rapid surface process in comparison with the case of the pure magnesium. This identification is reinforced by the employment of surface modification. 19 references, 2 figures, 1 table.

  1. Electrochemical Film Formation on Magnesium Metal in an Ionic Liquid That Dissolves Metal Triflate and Its Application to an Active Material with Anion Charge Carrier.

    PubMed

    Shiga, Tohru; Kato, Yuichi; Inoue, Masae

    2016-11-16

    Irregular metallic growth at the anode during recharging of batteries can seriously influence the safety of batteries. To address this problem, we have attempted to design active anode materials with anion charge carriers and recently observed the formation and dissolution of an electrochemical film by triflate anions (CF3SO3(-)) at the surface of magnesium in an ionic liquid (IL) electrolyte of Mg(CF3SO3)2, which represents a rare anode material. The effect of heterogeneous cations on film formation was examined in this work. In an IL that dissolves NaCF3SO3, sodium ions with a lower reduction potential than Mg(2+)/Mg would not be expected to assist film formation. However, to our surprise, we discovered that some sodium ions are involved in film formation. The sodium ions are believed to act as a cross-linking point for the formation of a film network, which resulted in fairly good reversibility for film formation. In a Ce(CF3SO3)3-IL electrolyte, an electrochemically formed film free of Ce(3+) was obtained. The trivalent cerium cations were deactivated and transformed to an oxide on Mg metal. However, the reversibility of film formation in the Ce(CF3SO3)3 system did not meet the expected level. By coupling the film formation and dissolution behavior with a V2O5 cathode, a rechargeable battery was fabricated with dual ion transport species of Na(+) or Ce(3+) for the cathode and CF3SO3(-) for the anode. The unique battery with NaCF3SO3 is demonstrated to exhibit good discharge/charge performance with long-term cyclability.

  2. Calcium and Magnesium Ions Are Membrane-Active against Stationary-Phase Staphylococcus aureus with High Specificity

    NASA Astrophysics Data System (ADS)

    Xie, Yuntao; Yang, Lihua

    2016-02-01

    Staphylococcus aureus (S. aureus) is notorious for its ability to acquire antibiotic-resistance, and antibiotic-resistant S. aureus has become a wide-spread cause of high mortality rate. Novel antimicrobials capable of eradicating S. aureus cells including antibiotic-resistant ones are thus highly desired. Membrane-active bactericides and species-specific antimicrobials are two promising sources of novel anti-infective agents for fighting against bacterial antibiotic-resistance. We herein show that Ca2+ and Mg2+, two alkaline-earth-metal ions physiologically essential for diverse living organisms, both disrupt model S. aureus membranes and kill stationary-phase S. aureus cells, indicative of membrane-activity. In contrast to S. aureus, Escherichia coli and Bacillus subtilis exhibit unaffected survival after similar treatment with these two cations, indicative of species-specific activity against S. aureus. Moreover, neither Ca2+ nor Mg2+ lyses mouse red blood cells, indicative of hemo-compatibility. This works suggests that Ca2+ and Mg2+ may have implications in targeted eradication of S. aureus pathogen including the antibiotic-resistant ones.

  3. Calcium and Magnesium Ions Are Membrane-Active against Stationary-Phase Staphylococcus aureus with High Specificity.

    PubMed

    Xie, Yuntao; Yang, Lihua

    2016-02-11

    Staphylococcus aureus (S. aureus) is notorious for its ability to acquire antibiotic-resistance, and antibiotic-resistant S. aureus has become a wide-spread cause of high mortality rate. Novel antimicrobials capable of eradicating S. aureus cells including antibiotic-resistant ones are thus highly desired. Membrane-active bactericides and species-specific antimicrobials are two promising sources of novel anti-infective agents for fighting against bacterial antibiotic-resistance. We herein show that Ca(2+) and Mg(2+), two alkaline-earth-metal ions physiologically essential for diverse living organisms, both disrupt model S. aureus membranes and kill stationary-phase S. aureus cells, indicative of membrane-activity. In contrast to S. aureus, Escherichia coli and Bacillus subtilis exhibit unaffected survival after similar treatment with these two cations, indicative of species-specific activity against S. aureus. Moreover, neither Ca(2+) nor Mg(2+) lyses mouse red blood cells, indicative of hemo-compatibility. This works suggests that Ca(2+) and Mg(2+) may have implications in targeted eradication of S. aureus pathogen including the antibiotic-resistant ones.

  4. Calcium and Magnesium Ions Are Membrane-Active against Stationary-Phase Staphylococcus aureus with High Specificity

    PubMed Central

    Xie, Yuntao; Yang, Lihua

    2016-01-01

    Staphylococcus aureus (S. aureus) is notorious for its ability to acquire antibiotic-resistance, and antibiotic-resistant S. aureus has become a wide-spread cause of high mortality rate. Novel antimicrobials capable of eradicating S. aureus cells including antibiotic-resistant ones are thus highly desired. Membrane-active bactericides and species-specific antimicrobials are two promising sources of novel anti-infective agents for fighting against bacterial antibiotic-resistance. We herein show that Ca2+ and Mg2+, two alkaline-earth-metal ions physiologically essential for diverse living organisms, both disrupt model S. aureus membranes and kill stationary-phase S. aureus cells, indicative of membrane-activity. In contrast to S. aureus, Escherichia coli and Bacillus subtilis exhibit unaffected survival after similar treatment with these two cations, indicative of species-specific activity against S. aureus. Moreover, neither Ca2+ nor Mg2+ lyses mouse red blood cells, indicative of hemo-compatibility. This works suggests that Ca2+ and Mg2+ may have implications in targeted eradication of S. aureus pathogen including the antibiotic-resistant ones. PMID:26865182

  5. Structural Basis for Calcium and Magnesium Regulation of a Large Conductance Calcium-activated Potassium Channel with β1 Subunits*

    PubMed Central

    Liu, Hao-Wen; Hou, Pan-Pan; Guo, Xi-Ying; Zhao, Zhi-Wen; Hu, Bin; Li, Xia; Wang, Lu-Yang; Ding, Jiu-Ping; Wang, Sheng

    2014-01-01

    Large conductance Ca2+- and voltage-activated potassium (BK) channels, composed of pore-forming α subunits and auxiliary β subunits, play important roles in diverse physiological activities. The β1 is predominately expressed in smooth muscle cells, where it greatly enhances the Ca2+ sensitivity of BK channels for proper regulation of smooth muscle tone. However, the structural basis underlying dynamic interaction between BK mSlo1 α and β1 remains elusive. Using macroscopic ionic current recordings in various Ca2+ and Mg2+ concentrations, we identified two binding sites on the cytosolic N terminus of β1, namely the electrostatic enhancing site (mSlo1(K392,R393)-β1(E13,T14)), increasing the calcium sensitivity of BK channels, and the hydrophobic site (mSlo1(L906,L908)-β1(L5,V6,M7)), passing the physical force from the Ca2+ bowl onto the enhancing site and S6 C-linker. Dynamic binding of these sites affects the interaction between the cytosolic domain and voltage-sensing domain, leading to the reduction of Mg2+ sensitivity. A comprehensive structural model of the BK(mSlo1 α-β1) complex was reconstructed based on these functional studies, which provides structural and mechanistic insights for understanding BK gating. PMID:24764303

  6. Mechanistic studies of copper(II)-aminoglycoside mediated DNA damage and magnesium catalyzed nuclease activity of hammerhead ribozyme

    NASA Astrophysics Data System (ADS)

    Patwardhan, Anjali A.

    The antibacterial activity of aminoglycosides stems from their high affinity binding to the 16S rRNA in bacteria resulting in inhibition of protein synthesis. Used to treat acute bacterial infections these antibiotics have limited applications due to their high dosage requirements and the emergence of resistant strains. We have synthesized and characterized Cu(II) derivatives of the aminoglycosides, kanamycin A, tobramycin, neamine, kanamycin B, neomycin B, and paromomycin. The first three exhibit preferential and tight binding to Cu(II) as against neomycin B and kanamycin B and paromomycin. EPR of frozen solutions and UV-visible spectroscopy suggest a change in geometry around the Cu(II) but the stabilities of the complexes in water differ. These copper derivatives efficiently cleave plasmid DNA at micromolar concentrations (hydrolytic) and at nanomolar concentrations in the presence co-reactants like hydrogen peroxide or ascorbic acid. Hydrolysis is multi turnover and exhibits Michelis-Menten kinetics with enzyme-like behavior whereas oxidative cleavage is highly specific with C-4' H abstraction resulting in characteristic base propenal and nucleotide base products. Hydroxyl radicals generated are copper based and are generated in close proximity of the substrate. Hammerhead ribozymes are selectively hydrolyzed in the presence of divalent ions with Mg2+ being the metal ion of choice in vivo . Our studies with complex ions like cobalt hexaammine and fac-triamminetriaquochromium(III) establish outer sphere interactions of Mg2+ with the hammerhead in the catalytic site. There are two sets of sites, one structural and one catalytic. Complex ions in the catalytic site and divalent ions in the structural site result in a slow but active hammerhead ribozyme suggesting that the complex ions are not inhibitory, contrary to what was suggested previously.

  7. Cerium relieves the inhibition of nitrogen metabolism of spinach caused by magnesium deficiency.

    PubMed

    Yin, Sitao; Ze, Yuguan; Liu, Chao; Li, Na; Zhou, Min; Duan, Yanmei; Hong, Fashui

    2009-12-01

    Magnesium is one of the essential elements for plant growth and cerium is a beneficial element for plant growth. However, the effects of the fact that cerium improves the nitrogen metabolism of plants under magnesium deficiency is poorly understood. The main aim of the study was to determine the role of cerium in the amelioration of magnesium-deficiency effects in spinach plants. Spinach plants were cultivated in Hoagland's solution. They were subjected to magnesium deficiency and to cerium chloride administered in the magnesium-present media and magnesium-deficient media. Spinach plants grown in the magnesium-present media and magnesium-deficient media were measured for key enzyme activities involved in nitrogen metabolism such as nitrate reductase, nitrite reductase, glutamate dehydrogenase, glutamate synthase, urease, glutamic–pyruvic transaminase, and glutamic–oxaloace protease transaminase. As the nitrogen metabolism in spinach was significantly inhibited by magnesium deficiency, it caused a significant reduction of spinach plant weight, leaf turning chlorosis. However, cerium treatment grown in magnesium-deficiency media significantly promoted the activities of the key enzymes as well as the contents of the free amino acids, chlorophyll, soluble protein, and spinach growth. It implied that Ce3+ could partly substitute for magnesium to facilitate the transformation from inorganic nitrogen to organic nitrogen, leading to the improvement of spinach growth, although the metabolism needs to be investigated further.

  8. A preorganized metalloreceptor for alkaline earth ions showing calcium versus magnesium selectivity in water: biological activity of selected metal complexes.

    PubMed

    Amatori, Stefano; Ambrosi, Gianluca; Fanelli, Mirco; Formica, Mauro; Fusi, Vieri; Giorgi, Luca; Macedi, Eleonora; Micheloni, Mauro; Paoli, Paola; Rossi, Patrizia

    2014-08-25

    The N,N'-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,N'-dimethylethylendiamine (Malten = L) forms the highly stable [CuH(-2)L] species in water, in which the converging maltol oxygen atoms form an electron-rich area able to host hard metal ions. When considering the alkaline earth series (AE), the [Cu(H(-2)L)] species binds all metal ions, with the exception of Mg(2+), exhibiting the relevant property to discriminate Ca(2+) versus Mg(2+) at physiological pH 7.4; the binding of the AE metal is visible to the naked eye. The stability constant values of the trinuclear [AE{Cu(H(-2)L)}2](2+) species formed reach the maximum for Ca(2+) (log K=7.7). Ca(2+) also forms a tetranuclear [Ca{Cu(H(-2)L)}]2(4+) species at a high Ca(2+) concentration. Tri- and tetranuclear calcium complexes show blue- and pink-colored crystals, respectively. [Cu(H(-2)L)] is the most active species in inducing DNA alterations. The DNA damages are compatible with its hydrolytic cleavages. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Antithrombotic effects of magnesium sulfate in in vivo experiments.

    PubMed

    Sheu, Joen R; Hsiao, George; Shen, Ming Y; Lee, Yen M; Yen, Mao H

    2003-05-01

    In this study, magnesium sulfate was effective in reducing the mortality of adenosine diphosphate-induced acute pulmonary thromboembolism in mice, when it was administered intravenously at doses of 100 and 200 microg/g body weight. In addition, intravenous injections of magnesium sulfate (100 and 200 microg/g) significantly prolonged bleeding time in the severed mesenteric arteries of rats by approximately 1.7- and 1.9-fold, respectively, compared with normal saline. Continuous infusion of magnesium sulfate (20 microg/g per minute) for 10 minutes also significantly increased the bleeding time by approximately 1.7-fold, and the bleeding time returned to baseline within 60 minutes of cessation of magnesium sulfate infusion. On the other hand, platelet thrombi formation was induced by irradiating mesenteric venules with filtered light in mice pretreated with intravenous fluorescein sodium. When magnesium sulfate was administered at 300 microg/g during induction of platelet plug formation with 10 microg/kg fluorescein sodium, occlusion time was not significantly prolonged, but a dose of 600 microg/g did significantly prolong the occlusion time. Furthermore, aspirin (250 microg/g) also showed a similar activity in this experiment in prolonging the occlusion time. In conclusion, these results suggest that magnesium sulfate has an effective antithrombotic activity in vivo, and treatment with magnesium sulfate may lower the risk of thromboembolic-related disorders.

  10. Nondestructive spot test method for magnesium and magnesium alloys

    NASA Technical Reports Server (NTRS)

    Wilson, M. L. (Inventor)

    1973-01-01

    A method for spot test identification of magnesium and various magnesium alloys commonly used in aerospace applications is described. The spot test identification involves color codes obtained when several drops of 3 M hydrochloric acid are placed on the surface to be tested. After approximately thirty seconds, two drops of this reacted acid is transferred to each of two depressions in a spot plate for additions of other chemicals with subsequent color changes indicating magnesium or its alloy.

  11. Highly Soluble Alkoxide Magnesium Salts for Rechargeable Magnesium Batteries

    SciTech Connect

    Liao, Chen; Guo, Bingkun; Jiang, Deen; Custelcean, Radu; Mahurin, Shannon Mark; Sun, Xiao-Guang; Dai, Sheng

    2014-01-01

    A unique class of air-stable and non-pyrophoric magnesium electrolytes has been developed based on alkoxide magnesium compounds. The crystals obtained from this class of electrolytes exhibit a unique structure of tri-magnesium cluster, [Mg3Cl3(OR)2(THF)6]+ [(THF)MgCl3] . High reversible capacities and good rate capabilities were obtained in Mg-Mo6S8 batteries using these new electrolytes at both 20 and 50 oC.

  12. Magnesium borohydride: from hydrogen storage to magnesium battery.

    PubMed

    Mohtadi, Rana; Matsui, Masaki; Arthur, Timothy S; Hwang, Son-Jong

    2012-09-24

    Beyond hydrogen storage: The first example of reversible magnesium deposition/stripping onto/from an inorganic salt was seen for a magnesium borohydride electrolyte. High coulombic efficiency of up to 94 % was achieved in dimethoxyethane solvent. This Mg(BH(4))(2) electrolyte was utilized in a rechargeable magnesium battery. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Magnesium fluoride recovery method

    DOEpatents

    Gay, Richard L.; McKenzie, Donald E.

    1989-01-01

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is contacted with an acid under certain prescribed conditions to produce a liquid product and a particulate solid product. The particulate solid product is separated from the liquid and treated at least two more times with acid to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 pCi/gm. In accordance with a particularly preferred embodiment of the invention a catalyst and an oxidizing agent are used during the acid treatment and preferably the acid is sulfuric acid having a strength of about 1.0 Normal.

  14. Constraining magnesium cycling in marine sediments using magnesium isotopes

    NASA Astrophysics Data System (ADS)

    Higgins, J. A.; Schrag, D. P.

    2010-09-01

    Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid δ 26Mg values increase with depth by as much as 2‰. Because carbonates preferentially incorporate 24Mg (low δ 26Mg), the increase in pore-fluid δ 26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid δ 26Mg values decrease with depth by up to 2‰. The decline in pore-fluid δ 26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion-advection-reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured δ 26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0-2.7‰ depleted in δ 26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the

  15. The Magnesium Chelation Step in Chlorophyll Biosynthesis

    SciTech Connect

    Gregory L. Dilworth, Ph.D Chemical Sciences, Geosciences and Biosciences Division Office of Basis Energy Sciences, greg.dilworth@science.doe.gov

    2001-01-17

    The progress described in this report encompasses work supported by DOE grant DE-FG09-89ER13989 for the period 2/15/92 to the present 6/14/94. The goals of the project were to continue investigating the enzymology of Mg-chelatase and to investigate the co-regulation of heme and chlorophyll formation in intact plastids. During this period the laboratory had additional support (two years) from USDA to investigate heme metabolism in chloroplasts. This report is arranged so that the progress is described by reference to manuscripts which are published, under review or in preparation.

  16. Magnesium in Prevention and Therapy.

    PubMed

    Gröber, Uwe; Schmidt, Joachim; Kisters, Klaus

    2015-09-23

    Magnesium is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status-primarily hypomagnesemia as it is seen more common than hypermagnesemia-might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium's many functions within the human body, it plays an important role in prevention and treatment of many diseases. Low levels of magnesium have been associated with a number of chronic diseases, such as Alzheimer's disease, insulin resistance and type-2 diabetes mellitus, hypertension, cardiovascular disease (e.g., stroke), migraine headaches, and attention deficit hyperactivity disorder (ADHD).

  17. Low brain magnesium in migraine

    SciTech Connect

    Ramadan, N.M.; Halvorson, H.; Vande-Linde, A.; Levine, S.R.; Helpern, J.A.; Welch, K.M.

    1989-10-01

    Brain magnesium was measured in migraine patients and control subjects using in vivo 31-Phosphorus Nuclear Magnetic Resonance Spectroscopy. pMg and pH were calculated from the chemical shifts between Pi, PCr and ATP signals. Magnesium levels were low during a migraine attack without changes in pH. We hypothesize that low brain magnesium is an important factor in the mechanism of the migraine attack.

  18. In vivo assessment of magnesium status in human body using accelerator-based neutron activation measurement of hands: a pilot study.

    PubMed

    Aslam; Pejović-Milić, A; McNeill, F E; Byun, S H; Prestwich, W V; Chettle, D R

    2008-02-01

    Magnesium (Mg) is an element essential for many enzymatic reactions in the human body. Various human and animal studies suggest that changes in Mg status are linked to diseases such as cardiac arrhythmia, coronary heart disease, hypertension, premenstrual syndrome, and diabetes mellitus. Thus, knowledge of Mg levels in the human body is needed. A direct measurement of human blood serum, which contains only 0.3% of the total body Mg, is generally used to infer information about the status of Mg in the body. However, in many clinical situations, Mg stored in large levels, for example in bones, muscles, and soft tissues, needs to be monitored either to evaluate the efficacy of a treatment or to study the progression of diseases associated with the deficiency of total body Mg. This work presents a feasibility study of a noninvasive, in vivo neutron activation analysis (IVNAA) technique using the 26Mg (n, gamma) 27Mg reaction to measure Mg levels in human hands. The technique employs the McMaster University high beam current Tandetron accelerator hand irradiation facility and an array of eight NaI (T1) detectors arranged in a 4 pi geometry for delayed counting of the 0.844 and 1.014 MeV gamma rays emitted when 27Mg decays in the irradiated hand. Mg determination in humans using IVNAA of hands has been demonstrated to be feasible, with effective doses as low as one-quarter of those delivered in chest x rays. The overall experimental uncertainty in the measurements is estimated to be approximately 5% (1 sigma). The results are found to be in the range of the in vitro measurements reported for other cortical bones collected from different sites of the human skeleton, which confirms that this technique mainly provides a measure of the amount of Mg in hand bones. The average concentration of Mg determined in human hands is 10.96 +/- 1.25 (+/- 1 SD) mg Mg/g Ca. The coefficient of variation (11%) observed in this study is comparable with or lower than several studies using in

  19. In vivo assessment of magnesium status in human body using accelerator-based neutron activation measurement of hands: A pilot study

    SciTech Connect

    Aslam; Pejovic-Milic, A.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Chettle, D. R.

    2008-02-15

    Magnesium (Mg) is an element essential for many enzymatic reactions in the human body. Various human and animal studies suggest that changes in Mg status are linked to diseases such as cardiac arrhythmia, coronary heart disease, hypertension, premenstrual syndrome, and diabetes mellitus. Thus, knowledge of Mg levels in the human body is needed. A direct measurement of human blood serum, which contains only 0.3% of the total body Mg, is generally used to infer information about the status of Mg in the body. However, in many clinical situations, Mg stored in large levels, for example in bones, muscles, and soft tissues, needs to be monitored either to evaluate the efficacy of a treatment or to study the progression of diseases associated with the deficiency of total body Mg. This work presents a feasibility study of a noninvasive, in vivo neutron activation analysis (IVNAA) technique using the {sup 26}Mg(n,{gamma}){sup 27}Mg reaction to measure Mg levels in human hands. The technique employs the McMaster University high beam current Tandetron accelerator hand irradiation facility and an array of eight NaI (T1) detectors arranged in a 4{pi} geometry for delayed counting of the 0.844 and 1.014 MeV gamma rays emitted when {sup 27}Mg decays in the irradiated hand. Mg determination in humans using IVNAA of hands has been demonstrated to be feasible, with effective doses as low as one-quarter of those delivered in chest x rays. The overall experimental uncertainty in the measurements is estimated to be approximately 5% (1{sigma}). The results are found to be in the range of the in vitro measurements reported for other cortical bones collected from different sites of the human skeleton, which confirms that this technique mainly provides a measure of the amount of Mg in hand bones. The average concentration of Mg determined in human hands is 10.96{+-}1.25 ({+-}1 SD) mg Mg/g Ca. The coefficient of variation (11%) observed in this study is comparable with or lower than several

  20. [Magnesium and the oxidative stress].

    PubMed

    Spasov, A A; Zheltova, A A; Kharitonov, M V

    2012-07-01

    Magnesium deficiency has been shown to result in alterations of cellular functions and biological activity of molecules. The review discusses possible relationship between Mg2+ deficiency and development of oxidative stress. Decrease of Mg2+ concentration in tissues and blood is accompanied with elevation of the oxidative stress markers, including products of the oxidative modification of lipids, proteins and DNA. The reduction in antioxidant defenses is synchronous with oxidative stress markers elevation. Different mechanisms including systemic reactions (hyperactivation of inflammation and endothelial dysfunction) and cellular changes (mitochondrial dysfunction and excessive production of fatty acids) are supposed to be involved in development and maintenance of the oxidative stress due to Mg2+ deficiency. Therefore the facts consolidated into the review evidence clear relation between Mg2+ deficiency and the oxidative stress development.

  1. [Magnesium disorder in metabolic bone diseases].

    PubMed

    Ishii, Akira; Imanishi, Yasuo

    2012-08-01

    Magnesium is abundantly distributed among the body. The half of the magnesium exists in the bone. In addition, magnesium is the second most abundant intracellular cation in vertebrates and essential for maintaining physiological function of the cells. Epidemiologic studies have demonstrated that magnesium deficiency is a risk factor for osteoporosis. The mechanism of bone fragility caused by magnesium deficiency has been intensely studied using animal models of magnesium deficiency. Magnesium deficiency causes decreased osteoblastic function and increased number of osteoclasts. Magnesium deficiency also accelerates mineralization in bone. These observations suggest that disturbed bone metabolic turnover and mineralization causes bone fragility.

  2. Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Status Interact with Vitamin D and/or Calcium Status?12

    PubMed Central

    Rosanoff, Andrea; Dai, Qi; Shapses, Sue A

    2016-01-01

    Although much is known about magnesium, its interactions with calcium and vitamin D are less well studied. Magnesium intake is low in populations who consume modern processed-food diets. Low magnesium intake is associated with chronic diseases of global concern [e.g., cardiovascular disease (CVD), type 2 diabetes, metabolic syndrome, and skeletal disorders], as is low vitamin D status. No simple, reliable biomarker for whole-body magnesium status is currently available, which makes clinical assessment and interpretation of human magnesium research difficult. Between 1977 and 2012, US calcium intakes increased at a rate 2–2.5 times that of magnesium intakes, resulting in a dietary calcium to magnesium intake ratio of >3.0. Calcium to magnesium ratios <1.7 and >2.8 can be detrimental, and optimal ratios may be ∼2.0. Background calcium to magnesium ratios can affect studies of either mineral alone. For example, US studies (background Ca:Mg >3.0) showed benefits of high dietary or supplemental magnesium for CVD, whereas similar Chinese studies (background Ca:Mg <1.7) showed increased risks of CVD. Oral vitamin D is widely recommended in US age-sex groups with low dietary magnesium. Magnesium is a cofactor for vitamin D biosynthesis, transport, and activation; and vitamin D and magnesium studies both showed associations with several of the same chronic diseases. Research on possible magnesium and vitamin D interactions in these human diseases is currently rare. Increasing calcium to magnesium intake ratios, coupled with calcium and vitamin D supplementation coincident with suboptimal magnesium intakes, may have unknown health implications. Interactions of low magnesium status with calcium and vitamin D, especially during supplementation, require further study. PMID:26773013

  3. Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Status Interact with Vitamin D and/or Calcium Status?

    PubMed

    Rosanoff, Andrea; Dai, Qi; Shapses, Sue A

    2016-01-01

    Although much is known about magnesium, its interactions with calcium and vitamin D are less well studied. Magnesium intake is low in populations who consume modern processed-food diets. Low magnesium intake is associated with chronic diseases of global concern [e.g., cardiovascular disease (CVD), type 2 diabetes, metabolic syndrome, and skeletal disorders], as is low vitamin D status. No simple, reliable biomarker for whole-body magnesium status is currently available, which makes clinical assessment and interpretation of human magnesium research difficult. Between 1977 and 2012, US calcium intakes increased at a rate 2-2.5 times that of magnesium intakes, resulting in a dietary calcium to magnesium intake ratio of >3.0. Calcium to magnesium ratios <1.7 and >2.8 can be detrimental, and optimal ratios may be ∼2.0. Background calcium to magnesium ratios can affect studies of either mineral alone. For example, US studies (background Ca:Mg >3.0) showed benefits of high dietary or supplemental magnesium for CVD, whereas similar Chinese studies (background Ca:Mg <1.7) showed increased risks of CVD. Oral vitamin D is widely recommended in US age-sex groups with low dietary magnesium. Magnesium is a cofactor for vitamin D biosynthesis, transport, and activation; and vitamin D and magnesium studies both showed associations with several of the same chronic diseases. Research on possible magnesium and vitamin D interactions in these human diseases is currently rare. Increasing calcium to magnesium intake ratios, coupled with calcium and vitamin D supplementation coincident with suboptimal magnesium intakes, may have unknown health implications. Interactions of low magnesium status with calcium and vitamin D, especially during supplementation, require further study. © 2016 American Society for Nutrition.

  4. Magnesium Hall Thruster

    NASA Technical Reports Server (NTRS)

    Szabo, James J.

    2015-01-01

    This Phase II project is developing a magnesium (Mg) Hall effect thruster system that would open the door for in situ resource utilization (ISRU)-based solar system exploration. Magnesium is light and easy to ionize. For a Mars- Earth transfer, the propellant mass savings with respect to a xenon Hall effect thruster (HET) system are enormous. Magnesium also can be combusted in a rocket with carbon dioxide (CO2) or water (H2O), enabling a multimode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in situ on Mars or the moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium-power (1- to 3-kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate a specific impulse (Isp) greater than 4,000 s was achieved at a discharge potential of 400 V. The feasibility of delivering fluidized Mg powder to a medium- or high-power thruster also was demonstrated. Phase II of the project evaluated the performance of an integrated, highpower Mg Hall thruster system in a relevant space environment. Researchers improved the medium power thruster system and characterized it in detail. Researchers also designed and built a high-power (8- to 20-kW) Mg HET. A fluidized powder feed system supporting the high-power thruster was built and delivered to Busek Company, Inc.

  5. Lithium-aluminum-magnesium electrode composition

    DOEpatents

    Melendres, Carlos A.; Siegel, Stanley

    1978-01-01

    A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

  6. Magnesium reduction of uranium oxide

    SciTech Connect

    Elliott, G.R.B.

    1985-08-13

    A method and apparatus are provided for reducing uranium oxide with magnesium to form uranium metal. The reduction is carried out in a molten-salt solution of density greater than 3.4 grams per cubic centimeter, thereby allowing the uranium product to sink and the magnesium oxide byproduct to float, consequently allowing separation of product and byproduct.

  7. Electrolytes for magnesium electrochemical cells

    DOEpatents

    Burrell, Anthony K.; Sa, Niya; Proffit, Danielle Lee; Lipson, Albert; Liao, Chen; Vaughey, John T.; Ingram, Brian J.

    2017-07-04

    An electrochemical cell includes a high voltage cathode configured to operate at 1.5 volts or greater; an anode including Mg.sup.0; and an electrolyte including an ether solvent and a magnesium salt; wherein: a concentration of the magnesium salt in the ether is 1 M or greater.

  8. Innovative Vacuum Distillation for Magnesium Recycling

    NASA Astrophysics Data System (ADS)

    Zhu, Tianbai; Li, Naiyi; Mei, Xiaoming; Yu, Alfred; Shang, Shixiang

    Magnesium recycling now becomes a very important subject as magnesium consumption increases fast around the world. All commonly used magnesium die-casting alloys can be recycled and recovered to the primary metal quality. The recycled materials may be comprised of biscuits, sprues, runners, flash, overflows, dross, sludge, scrap parts, and old parts that are returned from service, An innovative magnesium recycle method, vacuum distillation, is developed and proved out to be able to recycle magnesium scraps, especially machining chips, oily magnesium, smelting sludge, dross or the mixture. With this process at a specific temperature and environment condition, magnesium in scraps can be gasified and then solidified to become crystal magnesium crown. This `recycled' magnesium crown is collected and used as the raw material of magnesium alloys. The experimental results show the vacuum distillation is a feasible and plausible method to recycle magnesium. Further, the cost analysis will be addressed in this paper.

  9. Magnesium substitution in brushite cements.

    PubMed

    Alkhraisat, Mohammad Hamdan; Cabrejos-Azama, Jatsue; Rodríguez, Carmen Rueda; Jerez, Luis Blanco; Cabarcos, Enrique López

    2013-01-01

    The use of magnesium-doped ceramics has been described to modify brushite cements and improve their biological behavior. However, few studies have analyzed the efficiency of this approach to induce magnesium substitution in brushite crystals. Mg-doped ceramics composed of Mg-substituted β-TCP, stanfieldite and/or farringtonite were reacted with primary monocalcium phosphate (MCP) in the presence of water. The cement setting reaction has resulted in the formation of brushite and newberyite within the cement matrix. Interestingly, the combination of SAED and EDX analyses of single crystal has indicated the occurrence of magnesium substitution within brushite crystals. Moreover, the effect of magnesium ions on the structure, and mechanical and setting properties of the new cements was characterized as well as the release of Ca(2+) and Mg(2+) ions. Further research would enhance the efficiency of the system to incorporate larger amounts of magnesium ions within brushite crystals.

  10. Magnesium in Prevention and Therapy

    PubMed Central

    Gröber, Uwe; Schmidt, Joachim; Kisters, Klaus

    2015-01-01

    Magnesium is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status—primarily hypomagnesemia as it is seen more common than hypermagnesemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium’s many functions within the human body, it plays an important role in prevention and treatment of many diseases. Low levels of magnesium have been associated with a number of chronic diseases, such as Alzheimer’s disease, insulin resistance and type-2 diabetes mellitus, hypertension, cardiovascular disease (e.g., stroke), migraine headaches, and attention deficit hyperactivity disorder (ADHD). PMID:26404370

  11. Transition metal (Co, Ni) nanoparticles wrapped with carbon and their superior catalytic activities for the reversible hydrogen storage of magnesium hydride.

    PubMed

    Huang, Xu; Xiao, Xuezhang; Zhang, Wei; Fan, Xiulin; Zhang, Liuting; Cheng, Changjun; Li, Shouquan; Ge, Hongwei; Wang, Qidong; Chen, Lixin

    2017-02-01

    Magnesium hydride (MgH2) exhibits long-term stability and has recently been developed as a safe alternative to store hydrogen in the solid state, due to its high capacity of 7.6 wt% H2 and low cost compared to other metal hydrides. However, the high activation energy and poor kinetics of MgH2 lead to inadequate hydrogen storage properties, resulting in low energy efficiency. Nano-catalysis is deemed to be the most effective strategy in improving the kinetics performance of hydrogen storage materials. In this work, robust and efficient architectures of carbon-wrapped transition metal (Co/C, Ni/C) nanoparticles (8-16 nm) were prepared and used as catalysts in the MgH2 system via ball milling to improve its de/rehydrogenation kinetics. Between the two kinds of nano-catalysts, the Ni/C nanoparticles exhibit a better catalytic efficiency. MgH2 doped with 6% Ni/C (MgH2-6%Ni/C) exhibits a peak dehydrogenation temperature of 275.7 °C, which is 142.7, 54.2 and 32.5 °C lower than that of commercial MgH2, milled MgH2 and MgH2 doped with 6% Co/C (MgH2-6%Co/C), respectively. MgH2 doped with 6% Ni/C can release about 6.1 wt% H2 at 250 °C. More importantly, the dehydrogenated MgH2-6%Ni/C is even able to uptake 5.0 wt% H2 at 100 °C within 20 s. Moreover, a cycling test of MgH2 doped with 8% Ni/C demonstrates its excellent hydrogen absorption/desorption stability with respect to both capacity (up to 6.5 wt%) and kinetics (within 8 min at 275 °C for dehydrogenation and within 10 s at 200 °C for rehydrogenation). Mechanistic research reveals that the in situ formed Mg2Ni and Mg2NiH4 nanoparticles can be regarded as advanced catalytically active species in the MgH2-Ni/C system. Meanwhile, the carbon attached around the surface of transition metal nanoparticles can successfully inhibit the aggregation of the catalysts and achieve the steadily, prompting de/rehydrogenation during the subsequent cycling process. The intrinsic catalytic effects and the uniform distributions of Mg2Ni

  12. 21 CFR 331.11 - Listing of specific active ingredients.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., aluminum hydroxide-magnesium carbonate codried gel, aluminum hydroxide-magnesium trisilicate codried gel... or salt; maximum daily dosage limit 8 grams. (f) Glycine (aminoacetic acid). (g) Magnesium-containing active ingredients: (1) Hydrate magnesium aluminate activated sulfate. (2) Magaldrate. (3) Magnesium...

  13. Electrochemical performance of magnesium alloy and its application on the sea water battery.

    PubMed

    Zhao, Hongyang; Bian, Pei; Ju, Dongying

    2009-01-01

    The magnesium sea water battery belongs to a kind of reserved battery, which takes the active metal such as magnesium alloy as the anode based on the sea water as the electrolyte. Experiments of magnesium alloy sea water battery were carried out and its electrochemical performance was studied. Thin sheets of Mg-Al-Zn and Mg-Mn series of magnesium alloy were fabricated and used as the anode of magnesium battery. The discharging voltage and current were measured for different composition and thickness of Mg alloy sheet under various surface state, temperature as well as electrolyte. The effect of the temperature, the surface condition and the electrolyte to the electrical current and voltage were investigated. Anodic dissolution and mechanism of activation of Mg alloy anode were discussed based on surface microstructure observation. The feasibility to apply magnesium alloy sheet to highly effective sea water battery was verified.

  14. Briefly Bound to Activate: Transient Binding of a Second Catalytic Magnesium Activates the Structure and Dynamics of CDK2 Kinase for Catalysis

    SciTech Connect

    Bao, Zhao Qin; Jacobsen, Douglas M.; Young, Matthew A.

    2014-10-02

    We have determined high-resolution crystal structures of a CDK2/Cyclin A transition state complex bound to ADP, substrate peptide, and MgF{sub 3}{sup -}. Compared to previous structures of active CDK2, the catalytic subunit of the kinase adopts a more closed conformation around the active site and now allows observation of a second Mg{sup 2+} ion in the active site. Coupled with a strong [Mg{sup 2+}] effect on in vitro kinase activity, the structures suggest that the transient binding of the second Mg{sup 2+} ion is necessary to achieve maximum rate enhancement of the chemical reaction, and Mg{sup 2+} concentration could represent an important regulator of CDK2 activity in vivo. Molecular dynamics simulations illustrate how the simultaneous binding of substrate peptide, ATP, and two Mg{sup 2+} ions is able to induce a more rigid and closed organization of the active site that functions to orient the phosphates, stabilize the buildup of negative charge, and shield the subsequently activated {gamma}-phosphate from solvent.

  15. Briefly bound to activate: How the transient binding of a second catalytic Magnesium alters the structure and dynamics of the CDK2 protein kinase active site during catalysis

    PubMed Central

    Bao, Zhao Qin; Jacobsen, Douglas M.; Young, Matthew A.

    2012-01-01

    We have determined high resolution crystal structures of a CDK2/CyclinA transition-state complex bound to ADP, substrate peptide and MgF3−. Compared to previous structures of active CDK2, the catalytic subunit of the kinase adopts a more closed conformation around the active site and now allows observation of a second Mg2+ ion in the active site. Coupled with a strong [Mg2+] effect on in vitro kinase activity, the structures suggest that the transient binding of the second Mg2+ ion is necessary to achieve maximum rate-enhancement of the chemical reaction and Mg2+ concentration could represent an important regulator of CDK2 activity in vivo. Molecular dynamics simulations illustrate how the simultaneous binding of substrate peptide, ATP and two Mg2+ ions is able to induce a more rigid and closed organization of the active site that functions to orient the phosphates, stabilize the buildup of negative charge, and shield the subsequently activated γ-phosphate from solvent. PMID:21565702

  16. Magnesium sulphate for preventing preterm birth in threatened preterm labour.

    PubMed

    Crowther, Caroline A; Brown, Julie; McKinlay, Christopher J D; Middleton, Philippa

    2014-08-15

    Magnesium sulphate has been used in some settings as a tocolytic agent to inhibit uterine activity in women in preterm labour with the aim of preventing preterm birth. To assess the effects of magnesium sulphate therapy given to women in threatened preterm labour with the aim of preventing preterm birth and its sequelae. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (last searched 31 January 2014). Randomised controlled trials of magnesium sulphate as the only tocolytic, administered by any route, compared with either placebo, no treatment or alternative tocolytic therapy (not magnesium sulphate) to women considered to be in preterm labour. At least two review authors assessed trial eligibility and risk of bias and undertook data extraction independently. The 37 included trials (total of 3571 women and over 3600 babies) were generally of moderate to high risk of bias. Antenatal magnesium sulphate was compared with either placebo, no treatment, or a range of alternative tocolytic agents.For the primary outcome of giving birth within 48 hours after trial entry, no significant differences were seen between women who received magnesium sulphate and women who did not (whether placebo/no alternative tocolytic drug, betamimetics, calcium channel blockers, cox inhibitors, prostaglandin inhibitors, or human chorionic gonadotropin) (19 trials, 1913 women). Similarly for the primary outcome of serious infant outcome, there were no significant differences between the infants exposed to magnesium sulphate and those not (whether placebo/no alternative tocolytic drug, betamimetics, calcium channel blockers, cox inhibitors, prostaglandin inhibitors, human chorionic gonadotropin or various tocolytic drugs) (18 trials; 2187 babies). No trials reported the outcome of extremely preterm birth. In the seven trials that reported serious maternal outcomes, no events were recorded.In the group treated with magnesium sulphate compared with women receiving

  17. Synthesis of magnesium diboride by magnesium vapor infiltration process (MVIP)

    DOEpatents

    Serquis, Adriana C.; Zhu, Yuntian T.; Mueller, Frederick M.; Peterson, Dean E.; Liao, Xiao Zhou

    2003-01-01

    A process of preparing superconducting magnesium diboride powder by heating an admixture of solid magnesium and amorphous boron powder or pellet under an inert atmosphere in a Mg:B ratio of greater than about 0.6:1 at temperatures and for time sufficient to form said superconducting magnesium diboride. The process can further include exposure to residual oxygen at high synthesis temperatures followed by slow cooling. In the cooling process oxygen atoms dissolved into MgB.sub.2 segregated to form nanometer-sized coherent Mg(B,O) precipitates in the MgB.sub.2 matrix, which can act as flux pinning centers.

  18. Magnesium deficiency: What is our status

    USDA-ARS?s Scientific Manuscript database

    Low magnesium intake has been implicated in a broad range of cardiometabolic conditions, including diabetes, hypertension, and cardiovascular disease. Dietary magnesium and total body magnesium status have a widely-used but imperfect biomarker in serum magnesium. Despite serum magnesium’s limitation...

  19. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium oxide. 184.1431 Section 184.1431 Food and... Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4... powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or carbonate...

  20. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to crystallization...

  1. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to crystallization...

  2. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in aqueous...

  3. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4) occurs naturally as... a relatively dense white powder (heavy) by heating magnesium hydroxide or carbonate. Heating these...

  4. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium hydroxide. 184.1428 Section 184.1428... Listing of Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide... is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble magnesium...

  5. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... Specific Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No... bulky white powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or...

  6. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... Specific Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No... bulky white powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or...

  7. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to crystallization...

  8. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in aqueous...

  9. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in aqueous...

  10. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... mineral bischofite. It is prepared by dissolving magnesium oxide, hydroxide, or carbonate in aqueous...

  11. 21 CFR 184.1431 - Magnesium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium oxide. 184.1431 Section 184.1431 Food... Specific Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No... bulky white powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or...

  12. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium hydroxide. 184.1428 Section 184.1428... Listing of Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide... is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble magnesium...

  13. 21 CFR 184.1443 - Magnesium sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to crystallization...

  14. Mineral resource of the month: magnesium

    USGS Publications Warehouse

    Kramer, Deborah A.

    2012-01-01

    Magnesium is the eighthmost abundant element in Earth’s crust, and the second-most abundant metal ion in seawater. Although magnesium is found in more than 60 minerals, only brucite, dolomite, magnesite and carnallite are commercially important for their magnesium content. Magnesium and its compounds also are recovered from seawater, brines found in lakes and wells, and bitterns (salts).

  15. Dietary magnesium and urolithiasis in growing calves.

    PubMed

    Kallfelz, F A; Ahmed, A S; Wallace, R J; Sasangka, B H; Warner, R G

    1987-01-01

    The effect of high levels of dietary magnesium (1.4%) alone or in combination with elevated calcium (1.8%) or phosphorus (1.6%) on growth and health of male calves was evaluated during a nine week feeding trial after weaning. Twenty calves were randomly divided into 4 feeding groups consisting of controls, high magnesium, high magnesium and calcium or high magnesium and phosphorus. Elevated dietary minerals caused decreased feed intake and growth rate. Blood urea nitrogen and serum creatinine levels were greatly elevated in calves fed high magnesium or magnesium and phosphorus and serum urea nitrogen was moderately elevated in calves fed high magnesium and calcium. These elevations suggested the occurrence of renal damage as a result of microcrystalline obstruction of renal tubules. Serum magnesium levels were three times normal in calves fed high magnesium or magnesium and phosphorus, but only twice normal in calves fed high magnesium and calcium. High dietary magnesium resulted in a significant depression in blood calcium level. This effect was somewhat overcome by additional dietary calcium Three calves fed the high magnesium diet and two calves fed the high magnesium and phosphorus diet developed urinary tract obstruction. The chemical composition of uroliths recovered from these calves was calcium apatite. Elevated dietary magnesium has been shown to be a cause of urolithiasis in growing male calves. Additional dietary calcium, but not phosphorus, appears to protect calves against urolithiasis induced by elevated dietary magnesium.

  16. Understanding the effect of magnesium ion concentration on the catalytic activity of ribonuclease H through computation: Does a third metal binding site modulate endonuclease activity?

    PubMed Central

    Ho, Ming-Hsun; De Vivo, Marco; Peraro, Matteo Dal; Klein, Michael L.

    2010-01-01

    Ribonuclease H (RNase H) belongs to the nucleotidyl-transferase (NT) superfamily and hydrolyzes the phosphodiester linkage on the RNA strand of a DNA/RNA hybrid duplex. Due to its activity in HIV reverse transcription, it represents a promising target for anti-HIV drug design. While crystallographic data have located two ions in the catalytic site, there is ongoing debate concerning just how many metal ions bound at the active site are optimal for catalysis. Indeed, experiments have shown a dependency of the catalytic activity on the Mg2+ concentration. Moreover, in RNase H the glutamate residue E188 has been shown to be essential for full enzymatic activation regardless of the Mg2+ concentration. The catalytic center is known to contain two Mg2+ ions (Nowotny et al.) and E188 is not one of the primary metal ligands. Herein, classical molecular dynamics (MD) simulations are employed to study the metal-ligand coordination in RNase H at different concentration of Mg2+. Importantly, the presence of a third Mg2+ ion, bound to the second-shell ligand E188, is persistent feature of the MD simulations. Free energy calculations have identified two distinct conformations depending on the concentration of Mg2+. At standard concentration, a third Mg2+ is found in the catalytic pocket but it does not perturb the optimal RNase H active conformation. However, at higher concentration, the third Mg2+ ion heavily perturbs the nucleophilic water and thereby influences the catalytic efficiency of RNase H. In addition, the E188A mutant shows no ability to engage additional Mg2+ ions nearby the catalytic pocket. This finding likely explains the decrease in catalytic activity of E188A, and also supports the key role of E188 in localizing the third Mg2+ ion at the active site. Glutamate residues are commonly found surrounding the metal center in the endonuclease family, which suggests that this structural motif may be an important feature to enhance catalytic activity. The present MD

  17. Expanding Mg-Zn hybrid chemistry: inorganic salt effects in addition reactions of organozinc reagents to trifluoroacetophenone and the implications for a synergistic lithium-magnesium-zinc activation.

    PubMed

    Armstrong, David R; Clegg, William; García-Álvarez, Pablo; Kennedy, Alan R; McCall, Matthew D; Russo, Luca; Hevia, Eva

    2011-07-18

    Numerous organic transformations rely on organozinc compounds made through salt-metathesis (exchange) reactions from organolithium or Grignard reagents with a suitable zinc precursor. By combining X-ray crystallography, NMR spectroscopy and DFT calculations, this study sheds new light on the constitution of the organometallic species involved in this important synthetic tool. Investigations into the metathesis reactions of equimolar amounts of Grignard reagents (RMgX) and ZnCl(2) in THF led to the isolation of novel magnesium-zinc hybrids, [{(thf)(2)Mg(μ-Cl)(3)ZnR}(2)] (R=Et, tBu, nBu or o-OMe-C(6)H(4)), which exhibit an unprecedented structural motif in mixed magnesium-zinc chemistry. Furthermore, theoretical modelling of the reaction of EtMgCl with ZnCl(2) reveals that formation of the mixed-metal compound is thermodynamically preferred to that of the expected homometallic products, RZnCl and MgCl(2). This study also assesses the alkylating ability of hybrid 3 towards the sensitive ketone trifluoroacetophenone, revealing a dramatic increase in the chemoselectivity of the reaction when LiCl is introduced as an additive. This observation, combined with recent related breakthroughs in synthesis, points towards the existence of a trilateral Li/Mg/Zn synergistic effect.

  18. Physicochemical action of potassium-magnesium citrate in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Pak, C. Y.; Koenig, K.; Khan, R.; Haynes, S.; Padalino, P.

    1992-01-01

    Effect of potassium-magnesium citrate on urinary biochemistry and crystallization of stone-forming salts was compared with that of potassium citrate at same dose of potassium in five normal subjects and five patients with calcium nephrolithiasis. Compared to the placebo phase, urinary pH rose significantly from 6.06 +/- 0.27 to 6.48 +/- 0.36 (mean +/- SD, p less than 0.0167) during treatment with potassium citrate (50 mEq/day for 7 days) and to 6.68 +/- 0.31 during therapy with potassium-magnesium citrate (containing 49 mEq K, 24.5 mEq Mg, and 73.5 mEq citrate per day). Urinary pH was significantly higher during potassium-magnesium citrate than during potassium citrate therapy. Thus, the amount of undissociated uric acid declined from 118 +/- 61 mg/day during the placebo phase to 68 +/- 54 mg/day during potassium citrate treatment and, more prominently, to 41 +/- 46 mg/day during potassium-magnesium citrate therapy. Urinary magnesium rose significantly from 102 +/- 25 to 146 +/- 37 mg/day during potassium-magnesium citrate therapy but not during potassium citrate therapy. Urinary citrate rose more prominently during potassium-magnesium citrate therapy (to 1027 +/- 478 mg/day from 638 +/- 252 mg/day) than during potassium citrate treatment (to 932 +/- 297 mg/day). Consequently, urinary saturation (activity product) of calcium oxalate declined significantly (from 1.49 x 10(-8) to 1.03 x 10(-8) M2) during potassium-magnesium citrate therapy and marginally (to 1.14 x 10(-8) M2) during potassium citrate therapy.(ABSTRACT TRUNCATED AT 250 WORDS).

  19. Physicochemical action of potassium-magnesium citrate in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Pak, C. Y.; Koenig, K.; Khan, R.; Haynes, S.; Padalino, P.

    1992-01-01

    Effect of potassium-magnesium citrate on urinary biochemistry and crystallization of stone-forming salts was compared with that of potassium citrate at same dose of potassium in five normal subjects and five patients with calcium nephrolithiasis. Compared to the placebo phase, urinary pH rose significantly from 6.06 +/- 0.27 to 6.48 +/- 0.36 (mean +/- SD, p less than 0.0167) during treatment with potassium citrate (50 mEq/day for 7 days) and to 6.68 +/- 0.31 during therapy with potassium-magnesium citrate (containing 49 mEq K, 24.5 mEq Mg, and 73.5 mEq citrate per day). Urinary pH was significantly higher during potassium-magnesium citrate than during potassium citrate therapy. Thus, the amount of undissociated uric acid declined from 118 +/- 61 mg/day during the placebo phase to 68 +/- 54 mg/day during potassium citrate treatment and, more prominently, to 41 +/- 46 mg/day during potassium-magnesium citrate therapy. Urinary magnesium rose significantly from 102 +/- 25 to 146 +/- 37 mg/day during potassium-magnesium citrate therapy but not during potassium citrate therapy. Urinary citrate rose more prominently during potassium-magnesium citrate therapy (to 1027 +/- 478 mg/day from 638 +/- 252 mg/day) than during potassium citrate treatment (to 932 +/- 297 mg/day). Consequently, urinary saturation (activity product) of calcium oxalate declined significantly (from 1.49 x 10(-8) to 1.03 x 10(-8) M2) during potassium-magnesium citrate therapy and marginally (to 1.14 x 10(-8) M2) during potassium citrate therapy.(ABSTRACT TRUNCATED AT 250 WORDS).

  20. Magnesium Research and Technology Development

    SciTech Connect

    Nyberg, Eric A.; Carpenter, Joseph A.; Sklad, Philip S.

    2007-05-17

    The primary objective of this project is to provide DOE with high quality and state of the art information on magnesium R&D within the U.S. and around the world. The purpose of this information enables DOE to make informed decisions on direction for future funding related to magnesium applications within the U.S. and international cooperative programs. A second key objective is to serve as the Projecct Technical Committee representative for the 3-country Magnesium Front End R&D Project.

  1. Confession of a Magnesium Battery.

    PubMed

    Bucur, Claudiu B; Gregory, Thomas; Oliver, Allen G; Muldoon, John

    2015-09-17

    Magnesium is an ideal metal anode that has nearly double the volumetric capacity of lithium metal with a very negative reduction potential of -2.37 vs SHE. A significant advantage of magnesium is the apparent lack of dendrite formation during charging, which overcomes major safety and performance challenges encountered with using lithium metal anodes. Here, we highlight major recent advances in nonaqueous Mg electrochemistry, notably the development of electrolytes and cathodes, and discuss some of the challenges that must be overcome to realize a practical magnesium battery.

  2. Nonlinear anelasticity of magnesium

    NASA Astrophysics Data System (ADS)

    Aning, Alexander; Suzuki, Tetsuro; Wuttig, Manfred

    1982-10-01

    An approximate solution of the equation of motion of a nonlinear anelastic reed at or near resonance is presented. The steady state solution reproduces the well-known nonlinear resonances. The solution also predicts the existence of automodulations, i.e., self-excited modulations of the amplitude and phase at constant power of excitation of the reed. Numerical examples of such automodulations are presented for an antisymmetric deformation potential. Experimental studies of finite amplitude oscillations of a magnesium reed vibrating at 72 and 431 Hz at room temperature confirm the existence of automodulations. The experimental results can be semiquantitatively described in terms of the solution given. The assumption that finite deformation by twinning represents the essential nonlinearity leads to a self-consistent interpretation. The relaxation time of twinning is obtained from the analysis of the automodulation and is 22 msec in the sample investigated. It is proposed that point defects control the relaxation process.

  3. Magnesium: Engineering the Surface

    NASA Astrophysics Data System (ADS)

    Chen, X. B.; Yang, H. Y.; Abbott, T. B.; Easton, M. A.; Birbilis, N.

    2012-06-01

    Magnesium (Mg) and its alloys provide numerous benefits as lightweight materials; however, industrial deployment of Mg in most instances requires anticorrosion coatings. Engineering the Mg surface is an area that has been undergoing intense research recently. Surface engineering commences with the "pretreatment" step, which can be used to modify the surface composition and morphology, resulting in surface enrichment or depletion of alloying elements. Following this, electrochemical plating (including electro- and electroless plating) and conversion coatings have emerged as common means of coating Mg. In this study, we present the key aspects relating to the science and technology associated with pretreatment, electrochemical plating, and conversion coatings. This is followed by experimental examples of engineered surfaces of industrial relevance.

  4. (—) S-adenosyl-L-methionine-magnesium Protoporphyrin Methyltransferase, an Enzyme in the Biosynthetic Pathway of Chlorophyll in Zea mays 1

    PubMed Central

    Radmer, Richard J.; Bogorad, Lawrence

    1967-01-01

    The enzyme (—) S-adenosyl-L-methionine-magnesium protoporphyrin methyltransferase, which catalyzes the transfer of the methyl group from (—) S-adenosyl-L-methionine to magnesium protoporphyrin to form magnesium protoporphyrin monomethyl ester, has been detected in chloroplasts isolated from Zea mays. Zinc protoporphyrin and free protoporphyrin also act as substrates in the system, although neither one is as active as magnesium protoporphyrin. The following scheme of chlorophyll synthesis in higher plants is proposed: δ-aminolevulinic acid → → → protoporphyrin → magnesium protoporphyrin → magnesium protoporphyrin monomethyl ester → → → chlorophyll a. PMID:6045301

  5. Analysis of magnesium from magnesium stearate in pharmaceutical tablet formulations using hydrophilic interaction liquid chromatography with nano quantity analyte detection.

    PubMed

    Risley, Donald S; Magnusson, Lars-Erik; Morow, Paul R; Aburub, Aktham

    2013-05-05

    This study demonstrates the use of hydrophilic interaction liquid chromatography with a nano quantity analyte detector for the retention, separation and detection of magnesium from magnesium stearate in tablet formulations for a drug product formulation blend containing a hydrochloride salt of a weakly basic compound as the active ingredient. The nano quantity analyte detector can provide direct detection of inactive excipients and inorganic salts lacking ultraviolet chromophores, as well as, all non-volatile compounds. The separation was accomplished using a SeQuant ZIC-HILIC column and mobile phase consisting of 32.5:32.5:35 of acetone/methanol/ammonium formate buffer (150 mM, pH 4.5). Common validation parameters were evaluated to assess the method's quantitative potential for magnesium (from magnesium stearate) including: linearity, accuracy, specificity, solution stability, repeatability, and intermediate precision. Overall, the method described in this report proved to be very robust and represents a novel technique to conveniently separate and detect magnesium from magnesium stearate in pharmaceutical preparations both quickly and accurately.

  6. The effects of magnesium on potassium transport in ferret red cells.

    PubMed Central

    Flatman, P W

    1988-01-01

    1. The magnesium dependence of net and isotopic (using 86Rb as tracer) potassium transport was measured in fed ferret red cells. Bumetanide (0.1 mM) was used to dissect total flux into two components: bumetanide sensitive and bumetanide resistant. 2. Increasing the external magnesium concentration from zero (added) to 2 mM stimulated bumetanide-sensitive uptake by 16% but inhibited the bumetanide-resistant component by about 20%. 3. Ionophore A23187 was used to control internal magnesium concentration. A23187 was usually present in the cells during measurement of isotopic fluxes but was washed away before measurement of net fluxes. The magnesium-buffering characteristics of fed ferret red cells were assessed during these experiments. The cytoplasm acts as a high-capacity, low-affinity magnesium buffer over most of the range. Some high-affinity binding was seen in the presence of A23187 and 2 mM-EDTA. 4. A23187 itself slightly inhibits bumetanide-sensitive potassium transport. 5. Bumetanide-sensitive potassium transport is strongly dependent on the concentration of internal ionized magnesium. Transport is 35% maximal at 10(-7) M and increases up to the maximal rate at 1.3 mM. Further increase in ionized magnesium concentration to 3.5 mM has no additional effect. The curve relating activity to magnesium concentration is steepest at the physiological magnesium concentration. The effects of changing magnesium concentration are fully reversible. 6. Reduction of internal ionized magnesium concentration to 10(-7) M with A23187 and EDTA approximately doubles bumetanide-resistant potassium transport. 7. Bumetanide-sensitive fluxes occur via the sodium-potassium-chloride co-transport system under the conditions used. Results described in this paper thus suggest that internal magnesium may be an important physiological controller of sodium-potassium-chloride co-transport activity. PMID:3137332

  7. The effects of magnesium on potassium transport in ferret red cells.

    PubMed

    Flatman, P W

    1988-03-01

    1. The magnesium dependence of net and isotopic (using 86Rb as tracer) potassium transport was measured in fed ferret red cells. Bumetanide (0.1 mM) was used to dissect total flux into two components: bumetanide sensitive and bumetanide resistant. 2. Increasing the external magnesium concentration from zero (added) to 2 mM stimulated bumetanide-sensitive uptake by 16% but inhibited the bumetanide-resistant component by about 20%. 3. Ionophore A23187 was used to control internal magnesium concentration. A23187 was usually present in the cells during measurement of isotopic fluxes but was washed away before measurement of net fluxes. The magnesium-buffering characteristics of fed ferret red cells were assessed during these experiments. The cytoplasm acts as a high-capacity, low-affinity magnesium buffer over most of the range. Some high-affinity binding was seen in the presence of A23187 and 2 mM-EDTA. 4. A23187 itself slightly inhibits bumetanide-sensitive potassium transport. 5. Bumetanide-sensitive potassium transport is strongly dependent on the concentration of internal ionized magnesium. Transport is 35% maximal at 10(-7) M and increases up to the maximal rate at 1.3 mM. Further increase in ionized magnesium concentration to 3.5 mM has no additional effect. The curve relating activity to magnesium concentration is steepest at the physiological magnesium concentration. The effects of changing magnesium concentration are fully reversible. 6. Reduction of internal ionized magnesium concentration to 10(-7) M with A23187 and EDTA approximately doubles bumetanide-resistant potassium transport. 7. Bumetanide-sensitive fluxes occur via the sodium-potassium-chloride co-transport system under the conditions used. Results described in this paper thus suggest that internal magnesium may be an important physiological controller of sodium-potassium-chloride co-transport activity.

  8. Magnesium deficiency impairs fear conditioning in mice.

    PubMed

    Bardgett, Mark E; Schultheis, Patrick J; McGill, Diana L; Richmond, Raymond E; Wagge, Jordan R

    2005-03-15

    Magnesium (Mg2+) is one of the most abundant cations found in the body. In the central nervous system, Mg2+ plays an important role in the function of N-methyl-D-aspartate (NMDA)-type glutamate receptors, which are centrally involved in memory processing. Despite the relatively large concentration of Mg2+ in the CNS, little is known about the behavioral consequences of Mg2+ deficiency. The purpose of this study was to address this issue by assessing fear conditioning and related behaviors in mice maintained on normal or Mg(2+)-deficient diets. Young adult male C57Bl/6J mice were placed on a control or Mg(2+)-deficient diet, and testing was conducted between 10 and 21 days later. Magnesium-deficient mice exhibited impairments in contextual and cued fear conditioning. These impairments could not be attributed to changes in locomotor activity, exploration, or pain sensitivity. Furthermore, Mg(2+)-deficient mice were more sensitive to the convulsant effects of a peripheral injection of NMDA (100 mg/kg, IP). The results suggest that magnesium deficiency can lead to specific impairments in emotional memory. Such impairments may be related to hypersensitivity of NMDA-type glutamate receptors in Mg(2+)-deficient mice.

  9. NMDA/glutamate mechanism of antidepressant-like action of magnesium in forced swim test in mice.

    PubMed

    Poleszak, Ewa; Wlaź, Piotr; Kedzierska, Ewa; Nieoczym, Dorota; Wróbel, Andrzej; Fidecka, Sylwia; Pilc, Andrzej; Nowak, Gabriel

    2007-12-01

    Antidepressant-like activity of magnesium in forced swim test (FST) was demonstrated previously. Also, enhancement of such activity by joint administration of magnesium and antidepressants was shown. However, the mechanism(s) involved in such activity remain to be established. In the present study we examined the involvement of NMDA/glutamate pathway in the magnesium activity in FST in mice. In the present study we investigated the effect of NMDA agonists on magnesium-induced activity in FST and the influence of NMDA antagonists with sub-effective doses of magnesium in this test. Magnesium-induced antidepressant-like activity was antagonized by N-methyl-d-aspartic acid (NMDA). Moreover, low, ineffective doses of NMDA antagonists (CGP 37849, L-701,324, d-cycloserine, and MK-801) administered together with low and ineffective doses of magnesium exhibit significant reduction of immobility time in FST. The active in FST doses of examined agents did not alter the locomotor activity (with an exception of increased activity induced by MK-801). The present study indicates the involvement of NMDA/glutamate pathway in the antidepressant-like activity of magnesium in mouse FST and further suggests antidepressant properties of magnesium.

  10. In defense of magnesium sulfate.

    PubMed

    Elliott, John P; Lewis, David F; Morrison, John C; Garite, Thomas J

    2009-06-01

    Magnesium sulfate has been used by obstetricians for more than 25 years to treat preterm labor. Magnesium sulfate is effective in delaying delivery for at least 48 hours in patients with preterm labor when used in higher dosages. There do not seem to be any harmful effects of the drug on the fetus, and indeed there is a neuroprotective effect in reducing the incidence of cerebral palsy in premature newborns weighing less than 1,500 g.

  11. Thallium magnesium chloride: A high light yield, large effective atomic number, intrinsically activated crystalline scintillator for X-ray and gamma-ray detection

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yutaka; Koshimizu, Masanori; Yanagida, Takayuki; Okada, Go; Saeki, Keiichiro; Asai, Keisuke

    2016-09-01

    We report the luminescence and the scintillation properties of a newly developed thallium magnesium chloride (TlMgCl3) crystal. The crystal sample can be easily fabricated from the melt using the Bridgman method. The photoluminescence band appeared near the wavelength of 405 nm under excitation at 230 nm. An X-ray-induced scintillation spectrum showed an intense emission band near the wavelength of 405 nm. The decay time constant was estimated to be approximately 60 ns (∼25%) and 350 ns (∼75%) using a bi-exponential fitting. The scintillation light yield reached 46,000 photons/MeV with an energy resolution of 5% at 662 keV.

  12. Cement from magnesium substituted hydroxyapatite.

    PubMed

    Lilley, K J; Gbureck, U; Knowles, J C; Farrar, D F; Barralet, J E

    2005-05-01

    Brushite cement may be used as a bone graft material and is more soluble than apatite in physiological conditions. Consequently it is considerably more resorbable in vivo than apatite forming cements. Brushite cement formation has previously been reported by our group following the mixture of nanocrystalline hydroxyapatite and phosphoric acid. In this study, brushite cement was formed from the reaction of nanocrystalline magnesium-substituted hydroxyapatite with phosphoric acid in an attempt to produce a magnesium substituted brushite cement. The presence of magnesium was shown to have a strong effect on cement composition and strength. Additionally the presence of magnesium in brushite cement was found to reduce the extent of brushite hydrolysis resulting in the formation of HA. By incorporating magnesium ions in the apatite reactant structure the concentration of magnesium ions in the liquid phase of the cement was controlled by the dissolution rate of the apatite. This approach may be used to supply other ions to cement systems during setting as a means to manipulate the clinical performance and characteristics of brushite cements.

  13. Facile and fast fabrication of superhydrophobic surface on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Zhongwei; Li, Qing; She, Zuxin; Chen, Funan; Li, Longqin; Zhang, Xiaoxu; Zhang, Peng

    2013-04-01

    Superhydrophobic surface has many special functions and is widely investigated by researchers. Magnesium alloy is one of the lightest metal materials among the practice metals. It plays an important role in automobile, airplane and digital product for reducing devices weight. But due to the low standard potential, magnesium alloy has a high chemical activity and easily be corroded. That seriously impedes the application of magnesium alloy. In the process of fabrication a superhydrophobic surface on magnesium alloy, there are two ineluctable problems that must be solved: (1) high chemical activity and (2) the chemical activity is inhomogeneous on surface. In this study, we solved those problems by using the two characters to gain a rough surface on magnesium alloy and obtained a superhydrophobic surface after following modification process. The results show that the as-prepared superhydrophobic surface has obvious anti-corrosion effect in typically corrosive solution and naturally humid air. The delay-icing and self-cleaning effects are also investigated. The presented method is low-cost, fast and has great potential value in large-scale industry production.

  14. Magnesium and Dialysis: The Neglected Cation.

    PubMed

    Alhosaini, Mohamad; Leehey, David J

    2015-09-01

    Disorders of magnesium homeostasis are very common in dialysis patients but have received scant attention. In this review, we address measurement of plasma magnesium, magnesium balance and the factors that affect magnesium flux during dialysis, the prevalence of hypo- and hypermagnesemia in dialysis patients, and the potential clinical significance of hypo- and hypermagnesemia in dialysis patients. Many factors can affect plasma magnesium concentration, including diet, nutritional status (including plasma albumin level), medications (such as proton pump inhibitors), and dialysis prescription. Further interventional studies to determine the effect of normalization of plasma magnesium concentration on clinical outcomes are needed. At the present time, we recommend that predialysis plasma magnesium be measured on a regular basis, with the dialysate magnesium concentration adjusted to maintain plasma magnesium concentration within the normal range.

  15. Maternal magnesium sulfate fetal neuroprotective effects to the fetus: inhibition of neuronal nitric oxide synthase and nuclear factor kappa-light-chain-enhancer of activated B cells activation in a rodent model.

    PubMed

    Beloosesky, Ron; Khatib, Nizar; Ginsberg, Yuval; Anabosy, Saja; Shalom-Paz, Einat; Dahis, Masha; Ross, Michael G; Weiner, Zeev

    2016-09-01

    Maternal magnesium administration has been shown to protect the preterm fetus from white- and gray-matter injury, although the mechanism is unknown. The purpose of the study is to test the following hypotheses: (1) maternal infections/inflammation activate fetal neuronal N-methyl-D-aspartate receptors that up-regulate neuronal nitric oxide synthase and nuclear factor kappa-light-chain-enhancer of activated B cells pathways; and (2) maternal magnesium sulfate attenuates fetal brain neuronal nitric oxide synthase and nuclear factor kappa-light-chain-enhancer of activated B cells activation through N-methyl-D-aspartate receptors. Pregnant rats at embryonic day 16 and embryonic day 18 (n = 6, 48 total) received injections of intraperitoneal lipopolysaccharide 500 μg/kg or saline at time 0. Dams were randomized for treatment with subcutaneous magnesium sulfate (270 mg/kg) or saline for 2 hours prior to and following lipopolysaccharide/saline injections. At 4 hours after lipopolysaccharide administration, fetal brains were collected from the 4 treatment groups (lipopolysaccharide/saline, lipopolysaccharide/magnesium sulfate, saline/magnesium sulfate, saline/saline), and phosphoneuronal nitric oxide synthase, nuclear factor kappa-light-chain-enhancer of activated B cells p65, and chemokine (C-C motif) ligand 2 protein levels were determined by Western blot. An additional group of pregnant rats (n = 5) received N-methyl-D-aspartate-receptor antagonist following the lipopolysaccharide injection to study magnesium sulfate protective mechanism. Lipopolysaccharide (lipopolysaccharide/saline) significantly increased fetal brain phosphoneuronal nitric oxide synthase, nuclear factor kappa-light-chain-enhancer of activated B cells p65, and chemokine (C-C motif) ligand 2 protein levels compared to the saline/saline group at both embryonic day 16 (phosphoneuronal nitric oxide synthase 0.23 ± 0.01 vs 0.11 ± 0.01 U; nuclear factor kappa-light-chain-enhancer of activated B cells

  16. Magnesium Protects Cognitive Functions and Synaptic Plasticity in Streptozotocin-Induced Sporadic Alzheimer’s Model

    PubMed Central

    Bao, Jian; Wang, Zhi-Hao; Zeng, Juan; Liu, En-Jie; Li, Xiao-Guang; Huang, Rong-Xi; Gao, Di; Li, Meng-Zhu; Zhang, Yao; Liu, Gong-Ping; Wang, Jian-Zhi

    2014-01-01

    Alzheimer’s disease (AD) is characterized by profound synapse loss and impairments of learning and memory. Magnesium affects many biochemical mechanisms that are vital for neuronal properties and synaptic plasticity. Recent studies have demonstrated that the serum and brain magnesium levels are decreased in AD patients; however, the exact role of magnesium in AD pathogenesis remains unclear. Here, we found that the intraperitoneal administration of magnesium sulfate increased the brain magnesium levels and protected learning and memory capacities in streptozotocin-induced sporadic AD model rats. We also found that magnesium sulfate reversed impairments in long-term potentiation (LTP), dendritic abnormalities, and the impaired recruitment of synaptic proteins. Magnesium sulfate treatment also decreased tau hyperphosphorylation by increasing the inhibitory phosphorylation of GSK-3β at serine 9, thereby increasing the activity of Akt at Ser473 and PI3K at Tyr458/199, and improving insulin sensitivity. We conclude that magnesium treatment protects cognitive function and synaptic plasticity by inhibiting GSK-3β in sporadic AD model rats, which suggests a potential role for magnesium in AD therapy. PMID:25268773

  17. Cytotoxic effect of galvanically coupled magnesium-titanium particles.

    PubMed

    Kim, Jua; Gilbert, Jeremy L

    2016-01-01

    that during active corrosion of both Mg and Mg-Ti particles cells cultured with the particles are killed in a dose-dependent particle concentration fashion. Additionally, galvanically-coupled magnesium-titanium microparticles kill cells more effectively than magnesium particles alone. The killing effect was shown to not be due to pH shifts since no differences were seen for different particle types and pH adjusted medium without particles did not exhibit the same level of killing. The significance of this work is the recognition of this killing effect with Mg particles and the potential therapeutic applications in infection control and cancer treatment that this process may provide. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Leaf Senescence by Magnesium Deficiency

    PubMed Central

    Tanoi, Keitaro; Kobayashi, Natsuko I.

    2015-01-01

    Magnesium ions (Mg2+) are the second most abundant cations in living plant cells, and they are involved in various functions, including photosynthesis, enzyme catalysis, and nucleic acid synthesis. Low availability of Mg2+ in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis, necrotic spots on the leaves, and droop. During the last decade, a variety of physiological and molecular responses to Mg2+ deficiency that potentially link to leaf senescence have been recognized, allowing us to reconsider the mechanisms of Mg2+ deficiency. This review focuses on the current knowledge about the physiological responses to Mg2+ deficiency including a decline in transpiration, accumulation of sugars and starch in source leaves, change in redox states, increased oxidative stress, metabolite alterations, and a decline in photosynthetic activity. In addition, we refer to the molecular responses that are thought to be related to leaf senescence. With these current data, we give an overview of leaf senescence induced by Mg deficiency. PMID:27135350

  19. Magnesium Uptake by Soybeans

    PubMed Central

    Leggett, J. E.; Gilbert, W. A.

    1969-01-01

    Magnesium contents of soybean (Glycine max) roots increase and the K and Ca contents decrease with increased MgCl2 concentrations in ambient solutions. The Mg uptake is inhibited when both Ca and K are present in the solution, but not by K or Ca alone. Chloride uptake, which is very low from the MgCl2 solution, is greatly enhanced by the presence of K. The selectivity against Mg imparted by K + Ca appears to be at an external barrier for cation uptake as shown by its dependence on the presence of Ca in the external solution. The Ca content of roots is influenced only slightly by changes in external Ca concentrations from 10−4 to 10−2m, but that of shoots is greatly enhanced as the Ca concentration is increased or the K concentration is decreased. These effects on Ca contents are explained as arising from transport to the shoot without involvement of vacuoles of root cells. PMID:16657186

  20. Myth or Reality-Transdermal Magnesium?

    PubMed

    Gröber, Uwe; Werner, Tanja; Vormann, Jürgen; Kisters, Klaus

    2017-07-28

    In the following review, we evaluated the current literature and evidence-based data on transdermal magnesium application and show that the propagation of transdermal magnesium is scientifically unsupported. The importance of magnesium and the positive effects of magnesium supplementation are extensively documented in magnesium deficiency, e.g., cardiovascular disease and diabetes mellitus. The effectiveness of oral magnesium supplementation for the treatment of magnesium deficiency has been studied in detail. However, the proven and well-documented oral magnesium supplementation has become questioned in the recent years through intensive marketing for its transdermal application (e.g., magnesium-containing sprays, magnesium flakes, and magnesium salt baths). In both, specialist and lay press as well as on the internet, there are increasing numbers of articles claiming the effectiveness and superiority of transdermal magnesium over an oral application. It is claimed that the transdermal absorption of magnesium in comparison to oral application is more effective due to better absorption and fewer side effects as it bypasses the gastrointestinal tract.

  1. An efficient and economical treatment for batik textile wastewater containing high levels of silicate and organic pollutants using a sequential process of acidification, magnesium oxide, and palm shell-based activated carbon application.

    PubMed

    Birgani, Payam Moradi; Ranjbar, Navid; Abdullah, Rosniah Che; Wong, Kien Tiek; Lee, Gooyong; Ibrahim, Shaliza; Park, Chulhwan; Yoon, Yeomin; Jang, Min

    2016-12-15

    Considering the chemical properties of batik effluents, an efficient and economical treatment process was established to treat batik wastewater containing not only high levels of Si and chemical oxygen demand (COD), but also toxic heavy metals. After mixing the effluents obtained from the boiling and soaking steps in the batik process, acidification using concentrated hydrochloric acid (conc. HCl) was conducted to polymerize the silicate under acidic conditions. Consequently, sludge was produced and floated. XRD and FT-IR analyses showed that wax molecules were coordinated by hydrogen bonding with silica (SiO2). The acidification process removed ∼78-95% of COD and ∼45-50% of Si, depending on the pH. In the next stage, magnesium oxide (MgO) was applied to remove heavy metals completely and almost 90% of the Si in the liquid phase. During this step, about 70% of COD was removed in the hydrogel that arose as a consequence of the crosslinking characteristics of the formed nano-composite, such as magnesium silicate or montmorillonite. The hydrogel was composed mainly of waxes with polymeric properties. Then, the remaining Si (∼300 mg/L) in the wastewater combined with the effluents from the rinsing steps was further treated using 50 mg/L MgO. As a final step, palm-shell activated carbon (PSAC) was used to remove the remaining COD to < 50 mg/L at pH 3. Overall, the sequential process of acidification and MgO/PSAC application developed could serve as an economical and effective treatment option for treating heavily polluted batik effluents.

  2. System and process for production of magnesium metal and magnesium hydride from magnesium-containing salts and brines

    DOEpatents

    McGrail, Peter B.; Nune, Satish K.; Motkuri, Radha K.; Glezakou, Vassiliki-Alexandra; Koech, Phillip K.; Adint, Tyler T.; Fifield, Leonard S.; Fernandez, Carlos A.; Liu, Jian

    2016-11-22

    A system and process are disclosed for production of consolidated magnesium metal products and alloys with selected densities from magnesium-containing salts and feedstocks. The system and process employ a dialkyl magnesium compound that decomposes to produce the Mg metal product. Energy requirements and production costs are lower than for conventional processing.

  3. [Development of biodegradable magnesium-based biomaterials].

    PubMed

    Zhu, Shengfa; Xu, Li; Huang, Nan

    2009-04-01

    Magnesium is a macroelement which is indispensable to human bodies. As a lightweight metal with high specific strength and favorable biocompatibility, magnesium and its alloys have been introduced in the field of biomedical materials research and have a broad application prospect. It is possible to develop new type of biodegradable medical magnesium alloys by use of the poor corrosion resistance of magnesium. Bioabsorbable magnesium stents implanted in vivo could mechanically support the vessel in a short term, effectly prevent the acute coronary occlusion and in-stent restenosis, and then be gradully biodegraded and completely absorbed in a long term. Osteoconductive bioactivity in magnesium-based alloys could promote the apposition growth of bone tissue. This paper reviews the progress of magnesium and its alloys applied in bone tissue and cardiovascular stents, and the prospect of the future research of magnesium-based biomaterials is discussed.

  4. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... a white precipitate by the addition of sodium hydroxide to a water soluble magnesium salt or by hydration of reactive grades of magnesium oxide. (b) The ingredient meets the specifications of the Food...

  5. 21 CFR 184.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... is prepared as a white precipitate by the addition of sodium hydroxide to a water soluble magnesium salt or by hydration of reactive grades of magnesium oxide. (b) The ingredient meets the specifications...

  6. Magnesium/Calcium Competition at Excitable Membranes.

    ERIC Educational Resources Information Center

    Belzer, Bill; Fry, Panni

    1998-01-01

    Considers some consequences of altering intracellular calcium supply by magnesium concentration changes. Focuses on using this procedure as an exercise with allied health students as they witness therapeutic uses of magnesium and other calcium entry inhibitors. (DDR)

  7. Magnesium/Calcium Competition at Excitable Membranes.

    ERIC Educational Resources Information Center

    Belzer, Bill; Fry, Panni

    1998-01-01

    Considers some consequences of altering intracellular calcium supply by magnesium concentration changes. Focuses on using this procedure as an exercise with allied health students as they witness therapeutic uses of magnesium and other calcium entry inhibitors. (DDR)

  8. Magnesium silicide intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Li, Gh.; Gill, H. S.; Varin, R. A.

    1993-11-01

    Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 °C ± 5 °C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

  9. Effects of dietary magnesium on sodium-potassium pump action in the heart of rats

    SciTech Connect

    Fischer, P.W.; Giroux, A.

    1987-12-01

    Sprague-Dawley rats were fed a basal AIN-76 diet containing 80, 200, 350, 500 or 650 mg of magnesium per kilogram of diet for 6 wk. Ventricular slices, as well as microsomal fractions, were prepared from the hearts and were used to determine sodium-potassium pump activity. Sodium-potassium pump activity was assessed in the microsomal membranes by determining the ouabain-inhibitable Na+, K+-ATPase activity and (/sup 3/H)ouabain binding, and in the ventricular slices, by determining ouabain-sensitive /sup 86/Rb uptake under K+-free conditions. The ATPase activity increased with increasing dietary magnesium, so that in the hearts of those animals that were fed 500 and 650 mg of magnesium/kg diet, it was significantly greater than the activity in the hearts of the animals fed 80 and 200 mg/kg diet. Similarly, /sup 86/Rb uptake by heart slices from rats fed 500 and 650 mg of magnesium/kg diet was significantly greater than the uptake by heart slices from animals fed 80 and 200 mg/kg diet. (/sup 3/H)Ouabain binding did not change with increasing dietary magnesium. Thus, magnesium deficiency appears to have no effect on the number of sodium-potassium pump sites, but does decrease the activity of the pump. It is suggested that this leads to an increase in intracellular Na+, resulting in a change in the membrane potential, and may contribute to the arrhythmias associated with magnesium deficiency.

  10. Solid-state rechargeable magnesium battery

    DOEpatents

    Shao, Yuyan; Liu, Jun; Liu, Tianbiao; Li, Guosheng

    2016-09-06

    Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency .gtoreq.95% and exhibit cycling stability for at least 50 cycles.

  11. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium carbonate. 184.1425 Section 184.1425 Food... Specific Substances Affirmed as GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium carbonate...

  12. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate by...

  13. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate by...

  14. 21 CFR 184.1426 - Magnesium chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium chloride. 184.1426 Section 184.1426 Food... GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS Reg. No. 7786-30-3) is a... prepared by dissolving magnesium oxide, hydroxide, or carbonate in aqueous hydrochloric acid solution and...

  15. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium carbonate. 184.1425 Section 184.1425... Listing of Specific Substances Affirmed as GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium...

  16. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate by...

  17. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... Specific Substances Affirmed as GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate by...

  18. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium carbonate. 184.1425 Section 184.1425... GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium carbonate hydroxide. It is a white...

  19. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium carbonate. 184.1425 Section 184.1425... Listing of Specific Substances Affirmed as GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium...

  20. 21 CFR 184.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium carbonate. 184.1425 Section 184.1425... Listing of Specific Substances Affirmed as GRAS § 184.1425 Magnesium carbonate. (a) Magnesium carbonate (molecular formula approximately (MgCO3)4·Mg(OH)2·5H2O, CAS Reg. No. 39409-82-0) is also known as magnesium...

  1. 21 CFR 184.1440 - Magnesium stearate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium stearate. 184.1440 Section 184.1440 Food... GRAS § 184.1440 Magnesium stearate. (a) Magnesium stearate (Mg(C17H34COO)2, CAS Reg. No. 557-04-0) is the magnesium salt of stearic acid. It is produced as a white precipitate by the addition of an...

  2. Deleterious effects of magnesium intoxication upon the domestic broiler chick

    SciTech Connect

    Lee, S.R.

    1984-01-01

    Dietary levels of 0.6 to 0.8% magnesium in a corn-soy basal were rachitogenic. These rickets appeared most like phosphorus deficiency. Bone Ca/P ratios were numerically quite low implying a lack of transformation from amorphous calcium phosphate to hydroxyapatite. Bone alkaline phosphatase activity was elevated. Additional dietary phosphorus ameliorated, but could not overcome the rachitogenic effects of magnesium. Tibial dyschondroplasia (TD), induced by elevated dietary P, was decreased by high levels of dietary Mg, but with no decrease in plasma phosphorus. Anticoccidial ionophores fed in conjunction with a moderate dietary challenge of Mg (0.48%) produced no clear changes in plasma calcium or Mg, but did interact to reduce body weight. The diarrhea caused by magnesium intoxication is not due to hyperosmotic loads of Mg per se. Rather, Cl was observed to be the major ionic constituent of the gut osmotic load implying different gut ionic fluxes in control versus magnesium intoxicated chicks. These data imply that the cathartic action of Mg is due to hypersecretion of the gut. Effects mediated or modified by the CNS changed in magnesium intoxicated chicks. Such chicks appeared cold and stayed near the heat. When startled, they exhibited extreme avoidance behavior and seizures similar to epilepsy and/or Cl deficiency. Brain tissue Mg content did not concomitantly increase. Whether these effects are due to central signals is unclear.

  3. Antenatal magnesium sulfate: Neuro-protection for preterm infants.

    PubMed

    Oddie, S; Tuffnell, D J; McGuire, W

    2015-11-01

    The neuro-protective effect of antenatal magnesium sulfate on very preterm infants has been demonstrated in good-quality randomised controlled trials and meta-analyses. Magnesium administered prior to preterm delivery crosses over to the foetal circulation and acts via several pathways to reduce perinatal neuronal damage. Meta-analysis of the trial data indicates that antenatal magnesium sulfate reduces the risk of cerebral palsy by one-third, and results in one fewer case in every 50 women treated. Treatment is associated with discomfort and flushing in some women, but maternal side-effects are mostly transient and manageable. Magnesium sulfate has also been found to be without any serious adverse consequences in newborn infants. Consensus recommendations and guidelines have been developed and implemented internationally, and endorsed by the UK Royal College of Obstetricians and Gynaecologists. However, magnesium sulfate for neuro-protection of very preterm infants has not yet become established widely in UK practice. Paediatricians, neonatologists and advocacy groups for preterm infants and their families could contribute to raising awareness and engage in dissemination activities and implementation initiatives to develop local protocols for adoption of this safe, effective and cost-effective intervention to reduce the burden of cerebral palsy in children born very preterm. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  4. Physicochemical properties of magnesium salicylate.

    PubMed

    Alam, A S; Gregoriades, D

    1981-08-01

    Magnesium salicylate tetrahydrate is a nonhygroscopic, crystalline powder, whereas anhydrous magnesium salicylate is amorphous and very hygroscopic. Magnesium salicylate tetrahydrate tablets formulated with gelatin as a binder showed a dissolution half-life (t1/2) of 12 min, whereas a formulation using pregelatinized starch as a binder showed a t1/2 of 33 min. The optimum level of calcium stearate in the formulation was determined by the oscilloscope tracings of compressional and ejectional forces from an instrumented rotary tableting machine. Increasing the level of calcium stearate from 1 to 1.5 and 2% resulted in dissolution t1/2 values of 12, 18, and 21 min, respectively, and a higher incidence of softer tablets and capping.

  5. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

  6. 76 FR 69284 - Pure Magnesium From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ... COMMISSION Pure Magnesium From China Determination On the basis of the record \\1\\ developed in the subject... order on pure magnesium from China would be likely to lead to continuation or recurrence of material... USITC Publication 4274 (October 2011), entitled Pure Magnesium from China: Investigation No. 731-TA-696...

  7. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use. This...

  8. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

  9. Synthesis of superconducting magnesium diboride objects

    DOEpatents

    Finnemore, Douglas K.; Canfield, Paul C.; Bud'ko, Sergey L.; Ostenson, Jerome E.; Petrovic, Cedomir; Cunningham, Charles E.; Lapertot, Gerard

    2003-08-15

    A process to produce magnesium diboride objects from boron objects with a similar form is presented. Boron objects are reacted with magnesium vapor at a predetermined time and temperature to form magnesium diboride objects having a morphology similar to the boron object's original morphology.

  10. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  11. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use. This...

  12. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

  13. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium content...

  14. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use. This...

  15. Synthesis Of Superconducting Magnesium Diboride Objects.

    DOEpatents

    Finnemore, Douglas K.; Canfield, Paul C.; Bud'ko, Sergey L.; Ostenson, Jerome E.; Petrovic, Cedomir; Cunningham, Charles E.; Lapertot, Gerard

    2003-07-08

    A process to produce magnesium diboride objects from boron objects with a similar form is presented. Boron objects are reacted with magnesium vapor at a predetermined time and temperature to form magnesium diboride objects having a morphology similar to the boron object's original morphology.

  16. 21 CFR 582.5443 - Magnesium sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

  17. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use. This...

  18. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium content...

  19. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use. This...

  20. 21 CFR 582.5431 - Magnesium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  1. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use. This...

  2. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  3. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  4. 21 CFR 201.71 - Magnesium labeling.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium content...

  5. 21 CFR 582.5443 - Magnesium sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

  6. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  7. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use. This...

  8. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use. This...

  9. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2437 Magnesium silicate. (a) Product. Magnesium...

  10. 21 CFR 582.5443 - Magnesium sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

  11. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  12. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  13. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  14. 21 CFR 582.5431 - Magnesium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  15. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  16. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use. This...

  17. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  18. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

  19. 21 CFR 582.5431 - Magnesium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  20. 21 CFR 582.1431 - Magnesium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

  1. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium carbonate. 582.1425 Section 582.1425 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use. This...

  2. 21 CFR 582.5443 - Magnesium sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

  3. 21 CFR 582.5431 - Magnesium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  4. 21 CFR 582.5434 - Magnesium phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium phosphate. 582.5434 Section 582.5434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5434 Magnesium phosphate. (a) Product. Magnesium phosphate (di- and tribasic). (b...

  5. 21 CFR 582.5431 - Magnesium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  6. 21 CFR 582.5434 - Magnesium phosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium phosphate. 582.5434 Section 582.5434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5434 Magnesium phosphate. (a) Product. Magnesium phosphate (di- and tribasic). (b...

  7. 21 CFR 582.5443 - Magnesium sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

  8. 21 CFR 582.5434 - Magnesium phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium phosphate. 582.5434 Section 582.5434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5434 Magnesium phosphate. (a) Product. Magnesium phosphate (di- and tribasic). (b...

  9. 21 CFR 582.5434 - Magnesium phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium phosphate. 582.5434 Section 582.5434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5434 Magnesium phosphate. (a) Product. Magnesium phosphate (di- and tribasic). (b...

  10. 21 CFR 582.5434 - Magnesium phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium phosphate. 582.5434 Section 582.5434 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5434 Magnesium phosphate. (a) Product. Magnesium phosphate (di- and tribasic). (b...

  11. High Dietary Magnesium Intake Is Associated with Low Insulin Resistance in the Newfoundland Population

    PubMed Central

    Shea, Jennifer; Wadden, Danny; Gulliver, Wayne; Randell, Edward; Vasdev, Sudesh; Sun, Guang

    2013-01-01

    Background Magnesium plays a role in glucose and insulin homeostasis and evidence suggests that magnesium intake is associated with insulin resistance (IR). However, data is inconsistent and most studies have not adequately controlled for critical confounding factors. Objective The study investigated the association between magnesium intake and IR in normal-weight (NW), overweight (OW) and obese (OB) along with pre- and post- menopausal women. Design A total of 2295 subjects (590 men and 1705 women) were recruited from the CODING study. Dietary magnesium intake was computed from the Willett Food Frequency Questionnaire (FFQ). Adiposity (NW, OW and OB) was classified by body fat percentage (%BF) measured by Dual-energy X-ray absorptiometry according to the Bray criteria. Multiple regression analyses were used to test adiposity-specific associations of dietary magnesium intake on insulin resistance adjusting for caloric intake, physical activity, medication use and menopausal status. Results Subjects with the highest intakes of dietary magnesium had the lowest levels of circulating insulin, HOMA-IR, and HOMA-ß and subjects with the lowest intake of dietary magnesium had the highest levels of these measures, suggesting a dose effect. Multiple regression analysis revealed a strong inverse association between dietary magnesium with IR. In addition, adiposity and menopausal status were found to be critical factors revealing that the association between dietary magnesium and IR was stronger in OW and OB along with Pre-menopausal women. Conclusion The results of this study indicate that higher dietary magnesium intake is strongly associated with the attenuation of insulin resistance and is more beneficial for overweight and obese individuals in the general population and pre-menopausal women. Moreover, the inverse correlation between insulin resistance and dietary magnesium intake is stronger when adjusting for %BF than BMI. PMID:23472169

  12. The UK geochemical environment and cardiovascular diseases: magnesium in food and water.

    PubMed

    Davies, B E

    2015-06-01

    Cardiovascular diseases (CVDs) contribute approximately one-third to noncommunicable diseases in the UK. The central role of magnesium in CVDs (enzyme activity, cardiac signalling, etc.) is well established. Mortality and morbidity rates for CVDs may be inversely related to water hardness, suggesting a role for environmental magnesium. Published official and quasi-official data sources were evaluated to establish a model magnesium intake for a representative adult: standardised reference individual (SRI), standardised reference male (SRM) or standardised reference female (SRF). For typical dietary constituents, only tap water is probably locally derived and bottled water may not be. Fruits and vegetables are imported from many countries, while meat, dairy and cereal products represent a composite of UK source areas. Alcoholic beverages provide magnesium, there is doubt about its absorptive efficiency, and they are not locally derived. A simple model was devised to examine the effect of varying dietary contributions to total daily intake of magnesium. Omitting tap or bottled water, the combined intake, solid food plus alcoholic beverages, is 10.57 mmol Mg (84.5 % RNI) for the SRM and for the SRF, 8.10 mmol Mg (71.7 % RNI). Consumers drinking water derived from reservoirs or rivers, or supplementing it with the purest bottled water, improve their magnesium intake only slightly compared with water containing no magnesium. Choosing bottled water with high magnesium content when the public supply derives from rivers or reservoirs partially satisfies magnesium needs. Real improvement in SRI magnesium nutrition is seen only where water is hard. However, this conclusion cannot be validated until new measurement technologies for body magnesium become available.

  13. Neonatal serum magnesium concentrations are determined by total maternal dose of magnesium sulfate administered for neuroprotection.

    PubMed

    Borja-Del-Rosario, Pamela; Basu, Sudeepta Kumar; Haberman, Shoshana; Bhutada, Alok; Rastogi, Shantanu

    2014-03-01

    Antenatal magnesium in preterm labor for neuroprotection decreases the incidence of cerebral palsy. However, there are no guidelines on the dose and duration of magnesium infusion for neuroprotection. As increased neonatal serum magnesium concentrations may be related to higher risk of morbidity and mortality, the role of total amount of magnesium and maternal serum magnesium concentrations associated with safe neonatal serum magnesium concentrations is not known. A retrospective study was conducted on 289 mothers who received antenatal magnesium for neuroprotection as a loading dose of 4-6 g infused over 30 min, followed by a maintenance infusion of 1-2 g/h. Total magnesium dose infused to the mother and maternal serum magnesium concentrations were correlated with neonatal serum magnesium concentrations. Of the 289 mothers, 192 mother/baby dyads had all three measurements (maternal total magnesium dose, and maternal and neonatal serum magnesium concentrations). Magnesium infusion was continued beyond 24 h in 60 mothers. Total maternal magnesium dose at 24 and 48 h of infusion correlated with neonatal serum magnesium concentrations (r=0.55, P<0.0001 and r=0.35, P<0.0001, respectively), but not with maternal serum magnesium concentrations (r=0.004, P=0.98 and r=0.14, P=0.21). However, there was no correlation between the maternal and neonatal serum magnesium concentrations (r=0.10, P=0.15). Total dose of magnesium infused to the mother correlates with neonatal serum magnesium concentrations. To keep neonatal serum magnesium concentrations within a range that is effective for neuroprotection and safe for the neonates, the total dose received by the mother needs to be monitored and limited.

  14. Production, structure, texture, and mechanical properties of severely deformed magnesium

    NASA Astrophysics Data System (ADS)

    Volkov, A. Yu.; Antonova, O. V.; Kamenetskii, B. I.; Klyukin, I. V.; Komkova, D. A.; Antonov, B. D.

    2016-05-01

    Methods of the severe plastic deformation (SPD) of pure magnesium at room temperature, namely, transverse extrusion and hydroextrusion in a self-destroyed shell, have been developed. The maximum true strain of the samples after the hydroextrusion was e ~ 3.2; in the course of transverse extrusion and subsequent cold rolling, a true strain of e ~ 6.0 was achieved. The structure and mechanical properties of the magnesium samples have been studied in different structural states. It has been shown that the SPD led to a decrease in the grain size d to ~2 μm; the relative elongation at fracture δ increased to ~20%. No active twinning has been revealed. The reasons for the high plasticity of magnesium after SPD according to the deformation modes suggested are discussed from the viewpoint of the hierarchy of the observed structural states.

  15. High Strength and Thermally Stable Nanostructured Magnesium Alloys and Nanocomposites

    NASA Astrophysics Data System (ADS)

    Chang, Yuan-Wei

    Magnesium and its alloys are currently in the spotlight of global research because of the need to limit energy consumption and reduce the environmental impact. In particular, their low densities compared to other structural metals make them a very attractive alternative in the automobile and aerospace industries. However, their low strength compared to other structural materials (e.g. Al and steels) has limited their widespread application. This dissertation presents the results of developing and investigation of a high strength nanostructured magnesium-aluminum alloy and composite. The nanostructured magnesium alloy is prepared by cryomilling and consolidated by spark-plasma-sintering. Focused ion beam is used to prepare micropillars with different diameters ranging from 1.5 to 8 mum and micro-compression test is conducted by nanoindenter in order to evaluate the mechanical properties. The yield strength obtained in the present study is around three times higher than conventional magnesium alloys (120 MPa vs. 370 MPa). The yield strength of the nanostructured magnesium alloy is further improved through hot extrusion, resulting in a yield strength of 550 MPa and an ultimate strength of 580 MPa. The nanostructured magnesium alloy exhibits a strong size-dependence, and a significant improvement in strength is observed when the pillar diameter is reduced to below 3.5 mum. The deformation mechanisms of the compressed pillars were characterized using transmission electron microscopy. The size-induced strengthening is attributed to a less number of dislocation sources along with a higher activity of non-basal deformation mechanisms. We have also developed a high strength and thermally stable nanostructured magnesium composite by adding diamantane. A yield strength of 500 MPa is achieved, moreover, excellent thermal stability is demonstrated in the magnesium alloy containing diamantanes. The strength and grain size are thermally stable after annealing at 400°C for 100

  16. Magnesium Diboride Current Leads

    NASA Technical Reports Server (NTRS)

    Panek, John

    2010-01-01

    A recently discovered superconductor, magnesium diboride (MgB2), can be used to fabricate conducting leads used in cryogenic applications. Dis covered to be superconducting in 2001, MgB2 has the advantage of remaining superconducting at higher temperatures than the previously used material, NbTi. The purpose of these leads is to provide 2 A of electricity to motors located in a 1.3 K environment. The providing environment is a relatively warm 17 K. Requirements for these leads are to survive temperature fluctuations in the 5 K and 11 K heat sinks, and not conduct excessive heat into the 1.3 K environment. Test data showed that each lead in the assembly could conduct 5 A at 4 K, which, when scaled to 17 K, still provided more than the required 2 A. The lead assembly consists of 12 steelclad MgB2 wires, a tensioned Kevlar support, a thermal heat sink interface at 4 K, and base plates. The wires are soldered to heavy copper leads at the 17 K end, and to thin copper-clad NbTi leads at the 1.3 K end. The leads were designed, fabricated, and tested at the Forschungszentrum Karlsruhe - Institut foer Technische Physik before inclusion in Goddard's XRS (X-Ray Spectrometer) instrument onboard the Astro-E2 spacecraft. A key factor is that MgB2 remains superconducting up to 30 K, which means that it does not introduce joule heating as a resistive wire would. Because the required temperature ranges are 1.3-17 K, this provides a large margin of safety. Previous designs lost superconductivity at around 8 K. The disadvantage to MgB2 is that it is a brittle ceramic, and making thin wires from it is challenging. The solution was to encase the leads in thin steel tubes for strength. Previous designs were so brittle as to risk instrument survival. MgB2 leads can be used in any cryogenic application where small currents need to be conducted at below 30 K. Because previous designs would superconduct only at up to 8 K, this new design would be ideal for the 8-30 K range.

  17. Magnesium Decreases Inflammatory Cytokine Production: A Novel Innate Immunomodulatory Mechanism

    PubMed Central

    Sugimoto, Jun; Romani, Andrea M.; Valentin-Torres, Alice M.; Luciano, Angel A.; Ramirez Kitchen, Christina M.; Funderburg, Nicholas; Mesiano, Sam; Bernstein, Helene B.

    2013-01-01

    MgSO4 exposure before preterm birth is neuroprotective, reducing the risk of cerebral palsy and major motor dysfunction. Neonatal inflammatory cytokine levels correlate with neurologic outcome, leading us to assess the effect of MgSO4 on cytokine production in humans. We found reduced maternal TNF-α and IL-6 production following in vivo MgSO4 treatment. Short-term exposure to a clinically effective MgSO4 concentration in vitro substantially reduced the frequency of neonatal monocytes producing TNF-α and IL-6 under constitutive and TLR-stimulated conditions, decreasing cytokine gene and protein expression, without influencing cell viability or phagocytic function. In summary, MgSO4 reduced cytokine production in intrapartum women, term and preterm neonates, demonstrating effectiveness in those at risk for inflammation-associated adverse perinatal outcomes. By probing the mechanism of decreased cytokine production, we found that the immunomodulatory effect was mediated by magnesium and not the sulfate moiety, and it was reversible. Cellular magnesium content increased rapidly upon MgSO4 exposure, and reduced cytokine production occurred following stimulation with different TLR ligands as well as when magnesium was added after TLR stimulation, strongly suggesting that magnesium acts intracellularly. Magnesium increased basal IκBα levels, and upon TLR stimulation was associated with reduced NF-κB activation and nuclear localization. These findings establish a new paradigm for innate immunoregulation, whereby magnesium plays a critical regulatory role in NF-κB activation, cytokine production, and disease pathogenesis. PMID:22611240

  18. Intravenous magnesium in experimental stent thrombosis in swine.

    PubMed

    Rukshin, V; Azarbal, B; Shah, P K; Tsang, V T; Shechter, M; Finkelstein, A; Cercek, B; Kaul, S

    2001-09-01

    We investigated the effects of magnesium on acute platelet-dependent stent thrombosis in an ex vivo porcine arteriovenous shunt model of high-shear blood flow. Control nitinol stents were expanded to 2 mm in diameter in a tubular perfusion chamber interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100 s(-1) for 20 minutes (n=156 perfusion runs in 10 swine). Animals were treated with intravenous heparin or MgSO(4) alone (2 g bolus over 20 minutes, followed by 2 g/h infusion) and combined heparin plus MgSO(4) in random fashion. Effects on thrombus weight (TW), platelet aggregation, bleeding time, activated clotting time, mean arterial blood pressure, and heart rate were quantified. Data points in the magnesium-treated animals were examined within 20 minutes after bolus (Mg-early) and >40 minutes after bolus (Mg-late). Stent TW (20+/-3 mg, pretreatment) was reduced by 42+/-21%, 47+/-19%, 48+/-16%, 67+/-12%, and 86+/-8% in the groups treated with Mg-early alone, Mg-late alone, heparin alone, heparin+Mg-early, and heparin+Mg-late, respectively (all P<0.001 versus pretreatment, P<0.001 for heparin+Mg-early and Mg-late versus heparin or magnesium alone, and P<0.05 for heparin+Mg-late versus heparin+Mg-early, ANOVA). Magnesium had no significant effect on platelet aggregation, activated clotting time, or bleeding time. There were no significant effects on heart rate or mean arterial blood pressure. The serum magnesium level was inversely correlated with TW (r=-0.70, P=0.002). In conclusion, treatment with intravenous MgSO(4) produced a time-dependent inhibition of acute stent thrombosis under high-shear flow conditions without any hemostatic or significant hemodynamic complications. Thus, magnesium may be an effective agent for preventing stent thrombosis.

  19. Combustion Synthesis of Magnesium Aluminate

    SciTech Connect

    Kale, M. A.; Joshi, C. P.; Moharil, S. V.

    2011-10-20

    In the system MgO-Al{sub 2}O{sub 3}, three compounds MgAl{sub 2}O{sub 4}, MgAl{sub 6}O{sub 10}(also expressed as-Mg{sub 0.4}Al{sub 2.4}O{sub 4}) and MgAl{sub 26}O{sub 40} are well known. Importance of the first two is well established. Magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel is a technologically important material due to its interesting thermal properties. The MgAl{sub 2}O{sub 4} ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl{sub 2}O{sub 4} is due to various applications such as humidity-sensing and PEM fuel cells, TL/OSL dosimetry of the ionizing radiations, white light source. Interest in the MgAl{sub 6}O{sub 10} has aroused due to possible use as a substrate for GaN growth. Attempt was made to synthesize these compounds by the combustion synthesis using metal nitrates as oxidizer and urea as a fuel. Compounds MgAl{sub 2}O{sub 4} and MgAl{sub 6}O{sub 10} were formed in a single step, while MgAl{sub 26}O{sub 40} was not formed by this procedure. Activation of MgAl{sub 6}O{sub 10} by rare earth ions like Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+} and ns{sup 2} ion Pb{sup 2+} could be achieved. Excitation bands for MgAl{sub 6}O{sub 10} are at slightly shorter wavelengths compared to those reported for MgAl{sub 2}O{sub 4}.

  20. Biodegradation of metallic magnesium elicits an inflammatory response in primary nasal epithelial cells.

    PubMed

    Schumacher, S; Roth, I; Stahl, J; Bäumer, W; Kietzmann, M

    2014-02-01

    Resorbable magnesium-based implants hold great promise for various biomedical applications, such as osteosynthesis and coronary stenting. They also offer a new therapeutic option for the treatment of chronic rhinosinusitis, but little data is yet available regarding the use of magnesium in the nasal cavity. To model this field of application, primary porcine nasal epithelial cells were used to test the biocompatibility of degrading pure magnesium and investigate whether the degradation products may also affect cellular metabolism. Magnesium specimens did not induce apoptosis and we found no major influence on enzyme activities or protein synthesis, but cell viability was reduced and elevated interleukin 8 secretion indicated proinflammatory reactions. Necrotic damage was most likely due to osmotic stress, and our results suggest that magnesium ion build-up is also involved in the interleukin 8 release. Furthermore, the latter seems to be mediated, at least in part, by the p38 signaling pathway. These effects probably depended on the accumulation of very high concentrations of magnesium ions in the in vitro set-up, which might not be achieved in vivo, although we cannot exclude that further, as yet unknown, factors played a role in the inflammatory response during the degradation process. In conclusion, the biocompatibility of pure magnesium with cells in the immediate vicinity appears less ideal than is often supposed, and this needs to be considered in the evaluation of magnesium materials containing additional alloying elements. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. [Magnesium deficiency in an endocrinologist's practice].

    PubMed

    Tereshchenko, I V

    2008-01-01

    The review concerning a value of magnesium in an organism in healthy persons and cases with endocrine disorders is presented. The causes of magnesium-deficient conditions in cases with type 1 and type 2 diabetes, thyrotoxic goiter, hypothyroidism and obesity were analyzed. Participation of magnesium in secretion of parathormone and a control of calcium exchange is shown. The clinical semiology of hypomagnesemia seems to be nonspecific and manifold, and, therefore, as a rule, in most of endocrine patients magnesium deficiency remains to be undiagnosed. Questions on preventive measures and management of treatment magnesium-deficient conditions are considered.

  2. A SEARCH FOR MAGNESIUM IN EUROPA'S ATMOSPHERE

    SciTech Connect

    Hoerst, S. M.; Brown, M. E.

    2013-02-20

    Europa's tenuous atmosphere results from sputtering of the surface. The trace element composition of its atmosphere is therefore related to the composition of Europa's surface. Magnesium salts are often invoked to explain Galileo Near Infrared Mapping Spectrometer spectra of Europa's surface, thus magnesium may be present in Europa's atmosphere. We have searched for magnesium emission in the Hubble Space Telescope Faint Object Spectrograph archival spectra of Europa's atmosphere. Magnesium was not detected and we calculate an upper limit on the magnesium column abundance. This upper limit indicates that either Europa's surface is depleted in magnesium relative to sodium and potassium, or magnesium is not sputtered as efficiently resulting in a relative depletion in its atmosphere.

  3. Carbothermal Production of Magnesium in Vacuum

    NASA Astrophysics Data System (ADS)

    Qu, Tao; Yang, Bin; Tian, Yang; Dai, Yongnian

    Carbothermal production has been recognized as conceptually the cleanest and energy-efficient route to magnesium metal, but has suffered from technical challenges of development and scale-up. Work by National Engineering Laboratory for Vacuum Metallurgy of China has overcome some barriers of carbothermal production. By changing the condition of condensation, the magnesium vapor is condensed into bulk, so that the risk of magnesium powder explosion can be avoided, and it can reduce the oxygen content, enhance the recovered of magnesium. The mechanism of the carbothermic reduction process has be investigated, the reversion reactions are favored below 1373K at 30 100Pa, and reversion below 9% at bulk in condensation. Purification of magnesium by distillation is known technology, but difficulties with continuous operation are also known. In terms of process control, distillation temperature and pressure are controlled, the magnesium vapor is condensed into liquid, and then solidified into a solid, the solid magnesium is purified (>99.9%).

  4. [Magnesium: a kardio-renal viewpoint].

    PubMed

    Brandenburg, Vincent Matthias; Kaesler, Nadine; Kramann, Rafael; Floege, Jürgen; Marx, Nikolaus

    2016-10-01

    Disturbances in magnesium homeostasis are frequent clinical conditions, particularly the prevalence of hypomagnesaemia is high. However, it remains an open question which laboratory method is optimal to assess the magnesium level in the body. Most frequently physicians measure total magnesium in serum. Many associative data from observational studies point towards an association between low magnesium levels and increased cardiovascular risk as well as increased mortality. Vice versa, normal-to-high magnesium levels in patients with advanced renal failure translate to a better outcome. The present review summarizes our knowledge on protective effects of magnesium. Additionally, we address the limited evidence supporting targeted magnesium supplementation. © Georg Thieme Verlag KG Stuttgart · New York.

  5. Intracellular sodium, potassium and magnesium concentration, ouabain-sensitive 86rubidium-uptake and sodium-efflux and Na+, K+-cotransport activity in erythrocytes of normal male subjects studied on two occasions.

    PubMed

    Lijnen, P; Hespel, P; Lommelen, G; Laermans, M; M'Buyamba-Kabangu, J R; Amery, A

    1986-09-01

    The red cell Na+,K+-ATPase pump activity estimated by the ouabain-sensitive 86Rb-uptake or Na+-efflux, the Na+,K+-cotransport activity measured either by the furosemide-sensitive K+- or Na+- efflux or by the ethacrynic acid-sensitive 86Rb-uptake as well as the intraerythrocyte concentration of sodium, potassium and magnesium were studied in 29 normal male subjects with one to three weeks interval between the first and second blood sampling. Both the red cell sodium and potassium concentration, the erythrocyte ouabain-sensitive 86Rb-uptake and Na+-efflux, the furosemide-sensitive Na+- and K+-efflux and the ethacrynic acid-sensitive 86Rb-uptake are stable over time in the same individual. The furosemide-sensitive Na+-and K+-efflux is significantly related to the ethacrynic acid-sensitive 86Rb-uptake. The intraerythrocyte Na+ concentration was negatively related to the ouabain-sensitive 86Rb-uptake, but not to the ouabain-sensitive Na+-efflux; it was, however, negatively related to the rate constant for the ouabain-sensitive Na+-efflux.

  6. Magnesium therapy in a hypocalcemic African grey parrot (Psittacus erithacus).

    PubMed

    Kirchgessner, Megan S; Tully, Thomas N; Nevarez, Javier; Sanchez-Migallon Guzman, David; Acierno, Mark J

    2012-03-01

    Hypocalcemic-induced seizure activity is a clinical entity that is commonly diagnosed in neurologic African grey parrots (Psittacus erithacus). Plasma calcium levels are typically less than 6.0 mg/dL at the time of seizure activity, and although the underlying cause of the hypocalcemia has not yet been determined, many theories have been proposed. An African grey parrot that had been fed a seed diet for 8 years was presented with hypocalcemia and seizures and exhibited precipitously declining plasma calcium levels, despite aggressive calcium and vitamin A, D, and E supplementation for 4 days. Baseline magnesium levels in this parrot were determined to be 1.9 mg/dL; therefore, magnesium sulfate was administered at a dose of 20 mg/kg IM once. Twenty-four hours after supplementation, the plasma magnesium level was 3.3 mg/dL, and no further seizure activity was observed. We believe that a primary dietary magnesium deficiency may have been present in this African grey parrot, similar to a syndrome in leghorn chicks, which is frequently characterized by progressive hypocalcemia that is unable to be corrected by calcium supplementation alone.

  7. Measuring Serum Level of Ionized Magnesium in Patients with Migraine

    PubMed Central

    ASSARZADEGAN, Farhad; ASADOLLAHI, Mostafa; DERAKHSHANFAR, Hojjat; KASHEFIZADEH, Azam; ARYANI, Omid; KHORSHIDI, Mona

    2015-01-01

    Objective Migraine is known as one of the most disabling types of headache. Among the variety of theories to explain mechanism of migraine, role of serum magnesium is of great importance. Serum magnesium, as a pathogenesis factor, was considerably lower in patients with migraine. We established this study to see if serum ionized magnesium, not its total serum level, was different in migraineurs from normal individuals. Materials & Methods In this case control study, all participants were recruited from Neurology Clinic of Imam Hossein Hospital, Tehran, Iran. Ninety-six people were entered in the study, 48 for each of case and control groups. The two groups were matched by age and sex. Migrainous patients were selected according to the criteria of International Headache Society. Various characteristics of headache were recorded based on patients’ report. Controls had no history of migraine or any significant chronic headaches. Serum ionized magnesium level was measured in both of the case and control groups and the results were compared to each other. P value of <0.05 was considered as significant. Results Case group consisted of 13 males, 35 females, and control group included 14 males, as well as 34 females. Mean age was 33.47± 10.32 yr for case and 30.45 ±7.12 yr for control group. Twenty-eight patients described the intensity of their headaches as moderate; 15 patients had severe and the 5 remainders had only mild headaches. Mean serum level of ionized Mg was 1.16± 0.08 in case group and 1.13± 0.11 in control group of no significant difference (P >0.05). Conclusion Serum ionized magnesium, which is the active form of this ion, was not significantly different in migraineurs and those without migraine. This may propose a revision regarding pathogenesis of migraine and question the role of magnesium in this type of headache. PMID:26401148

  8. Attenuation of Magnesium Sulfate on CoCl₂-Induced Cell Death by Activating ERK1/2/MAPK and Inhibiting HIF-1α via Mitochondrial Apoptotic Signaling Suppression in a Neuronal Cell Line.

    PubMed

    Huang, Chih-Yang; Hsieh, You-Liang; Ju, Da-Tong; Lin, Chien-Chung; Kuo, Chia-Hua; Liou, Yi-Fan; Ho, Tsung-Jung; Tsai, Chang-Hai; Tsai, Fuu-Jen; Lin, Jing-Ying

    2015-08-31

    Magnesium sulfate (MgSO₄) ameliorates hypoxia/ischemia-induced neuronal apoptosis in a rat model. This study aimed to investigate the mechanisms governing the anti-apoptotic effect of MgSO₄ on cobalt chloride (CoCl₂)-exposed NB41A3 mouse neuroblastoma cells. MgSO₄ increased the viability of NB41A3 cells treated with CoCl₂ in a dose-dependent manner. MgSO₄ treatment was shown to lead to an increase in the anti-apoptotic Bcl-2 family proteins, with a concomitant decrease in the pro-apoptotic proteins. MgSO₄ also attenuated the CoCl₂-induced disruption of mitochondrial membrane potential (ΔΨ(m)) and reduced the release of cytochrome c form the mitochondria to the cytosol. Furthermore, exposure to CoCl₂ caused activation of the hypoxia-inducible factor 1α (HIF-1α). On the other hand, MgSO₄ markedly reduced CoCl₂-induced HIF-1α activation and suppressed HIF-1α downstream protein BNIP3. MgSO₄ treatment induced ERK1/2 activation and attenuated CoCl₂-induced activation of p38 and JNK. Addition of the ERK1/2 inhibitor U0126 significantly reduced the ability of MgSO₄ to protect neurons from CoCl₂-induced mitochondrial apoptotic events. However, incubation of cultures with the p38 and JNK inhibitors did not significantly affect MgSO₄-mediated neuroprotection. MgSO₄ appears to suppress CoCl₂-induced NB41A3 cell death by activating ERK1/2/ MAPK pathways, which further modulates the role of Bcl-2 family proteins and mitochondria in NB41A3 cells. Our data suggest that MgSO₄ may act as a survival factor that preserves mitochondrial integrity and inhibits apoptotic pathways.

  9. Magnesium-Based Corrosion Nano-Cells For Reductive Transformation Of Contaminants

    EPA Science Inventory

    Magnesium, with its potential to reduce a variety of aqueous contaminants, unique self-limiting corrosion behavior affording long active life times, natural abundance, low cost, and environmentally friendly nature, promises to be an effective technology. However, nanoparticles o...

  10. Magnesium-Based Corrosion Nano-Cells For Reductive Transformation Of Contaminants

    EPA Science Inventory

    Magnesium, with its potential to reduce a variety of aqueous contaminants, unique self-limiting corrosion behavior affording long active life times, natural abundance, low cost, and environmentally friendly nature, promises to be an effective technology. However, nanoparticles o...

  11. Magnesium reduces calcification in bovine vascular smooth muscle cells in a dose-dependent manner

    PubMed Central

    Peter, Mirjam E.; Sevinc Ok, Ebru; Celenk, Fatma Gul; Yilmaz, Mumtaz; Steppan, Sonja; Asci, Gulay; Ok, Ercan; Passlick-Deetjen, Jutta

    2012-01-01

    Background. Vascular calcification (VC), mainly due to elevated phosphate levels, is one major problem in patients suffering from chronic kidney disease. In clinical studies, an inverse relationship between serum magnesium and VC has been reported. However, there is only few information about the influence of magnesium on calcification on a cellular level available. Therefore, we investigated the effect of magnesium on calcification induced by β-glycerophosphate (BGP) in bovine vascular smooth muscle cells (BVSMCs). Methods. BVSMCs were incubated with calcification media for 14 days while simultaneously increasing the magnesium concentration. Calcium deposition, transdifferentiation of cells and apoptosis were measured applying quantification of calcium, von Kossa and Alizarin red staining, real-time reverse transcription–polymerase chain reaction and annexin V staining, respectively. Results. Calcium deposition in the cells dramatically increased with addition of BGP and could be mostly prevented by co-incubation with magnesium. Higher magnesium levels led to inhibition of BGP-induced alkaline phosphatase activity as well as to a decreased expression of genes associated with the process of transdifferentiation of BVSMCs into osteoblast-like cells. Furthermore, estimated calcium entry into the cells decreased with increasing magnesium concentrations in the media. In addition, higher magnesium concentrations prevented cell damage (apoptosis) induced by BGP as well as progression of already established calcification. Conclusions. Higher magnesium levels prevented BVSMC calcification, inhibited expression of osteogenic proteins, apoptosis and further progression of already established calcification. Thus, magnesium is influencing molecular processes associated with VC and may have the potential to play a role for VC also in clinical situations. PMID:21750166

  12. [A comparative study of antiarrhythmic and antihypoxic effects of magnesium sulfate, its prolonged form and blockers of calcium channels].

    PubMed

    Samsonia, M D; Kandelaki, M A

    2013-01-01

    The aim of the study is the comparative study of treatment of heart and brain damages during the hypoxia with magnesium sulfate, verapamil, diltiazem. As a result of the experiment carried out on rats it was proved that magnesium sulfate and its prolonged form are not less active than the blockers of calcium channels, such as verapamil and diltiazem. It is possible to avoid lethal fibrillations caused by calcium chloride with the help of 25% magnesium sulfate solution (after intraperitoneal administration with the dose of 1000 mg/kg) in case we make arrythmogenic injection 5 minutes after inputting magnesium sulfate solution. During the arrhythmia induced by calcium chloride prolonged form of magnesium sulfate is also effective only if we inject the drug subcutaneous 30 minutes before the arrythmogenic injection. If the interval is 5 minutes lethal fibrillations cant be avoided as the release of magnesium ions from the drug form is slowed down. The drugs containing magnesium ions also displayed cytoprotective activity on the model of normobaric hypoxia. This was resulted in the increase of protective index. Neuroprotective action of magnesium ions (in the condition of hypoxia) is caused by maintaining homeostasis of calcium ions and by inhibition of exocytosis of neuromediators in the synaptic cleft. Thus, magnesium sulfate and its prolonged form can be used with the purpose of pharmacocorrection of heart and brain injuries during hypoxic conditions.

  13. Electrical characterization of magnesium implanted gallium nitride

    NASA Astrophysics Data System (ADS)

    Krtschil, A.; Kielburg, A.; Witte, H.; Christen, J.; Krost, A.; Wenzel, A.; Rauschenbach, B.

    2002-01-01

    Gallium nitride layers grown by molecular beam epitaxy on c axis oriented sapphire substrates were implanted with 180 keV magnesium ions with ion doses between 1×1014 and 1×1016cm-2. The implantation induced defect states were investigated by temperature dependent conductivity (TDC) as well as by thermal and optical admittance spectroscopy (TAS, OAS) measurements. Dominant carrier emissions having thermal activation energies between 360 and 800 meV were found in TAS and TDC. These states are assigned to implantation induced electron traps since they do not appear in the nonimplanted reference sample. Defect states with similar transition energies were also observed in OAS resulting in an enhancement of defect-to-band transitions in the near band-gap region around 3.45 eV, in the blue band around 3.0 eV, as well as in the midgap range for photon energies between 2.5 and 1.80 eV, respectively. In addition, new transitions were found at 2.1 and 1.95 eV. Furthermore, transitions from implantation induced shallow states were observed, i.e., the magnesium acceptor as well as a new donor level at about 70 meV, tentatively discussed as nitrogen vacancy. The critical ion dose for amorphization was determined to be between 5×1015 and 1×1016Mg+ cm-2 using x-ray diffraction.

  14. The biological effects of magnesium-leached chrysotile asbestos.

    PubMed Central

    Morgan, A.; Davies, P.; Wagner, J. C.; Berry, G.; Holmes, A.

    1977-01-01

    Chrysotile asbestos was leached in N hydrochloric acid for varying times to produce a range of magnesium-depleted samples. The protein adsorptive capacity, the haemolytic activity, and the capacity to cause selective release of acid hydrolases from macrophages were measured for the various samples in vitro. The carcinogenicity of the same materials was determined following intrapleural inoculation in rats. The adsorptive capacity for albumin decreased linearly with magnesium removal. The haemolytic activity also declined until about half the magnesium had been removed, after which there was little further change. The selective release of acid hydrolases from macrophages in culture increased up to the point at which half the magnesium had been removed but by 90% depletion had declined rapidly. The carcinogenicity of 50% -depleted chrysotile was similar to that of intact, but at 90% depletion the incidence of mesothelial tumours had fallen considerably. There was no evidence that the leached samples fragmented more than the unleached in vivo. Images Fig. 1 PMID:588440

  15. A review of catalyst-enhanced magnesium hydride as a hydrogen storage material

    NASA Astrophysics Data System (ADS)

    Webb, C. J.

    2015-09-01

    Magnesium hydride remains an attractive hydrogen storage material due to the high hydrogen capacity and low cost of production. A high activation energy and poor kinetics at practical temperatures for the pure material have driven research into different additives to improve the sorption properties. This review details the development of catalytic additives and their effect on the activation energy, kinetics and thermodynamic properties of magnesium hydride.

  16. The magnesium chelation step in chlorophyll biosynthesis

    SciTech Connect

    Weinstein, J.

    1990-11-01

    In photosynthetic organisms, the biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins, and various lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX (Proto). Insertion of iron leads to the formation of hemes, while insertion of magnesium is the first step unique to chlorophyll formation. This project is directed toward identifying the enzyme(s) responsible for magnesium chelation and elucidating the mechanism which regulates the flux of precursors through the branch point enzymes in isolated chloroplasts. Using intact chloroplasts from greening cucumber cotyledons, we have confirmed the ATP requirement for Mg-Proto formation. Use of non-hydrolyzable ATP analogs, uncouplers and ionophores has led to the conclusions that ATP hydrolysis is necessary, but that this hydrolysis is not linked to the requirement for membrane intactness by transmembrane ion gradients or electrical potentials. The enzyme(s) are flexible with respect to the porphyrin substrate specificity, accepting porphyrins with -vinyl, -ethyl, or -H substituents at the 2 and 4 positions. The activity increases approximately four-fold during greening. Possible physiological feedback inhibitors such as heme, protochlorophyllide, and chlorophyllide had no specific effect on the activity. The activity has now been assayed in barely, corn and peas, with the system from peas almost ten-fold more active than the cucumber system. Work is continuing in pea chloroplasts with the development of a continuous assay and investigation of the feasibility of characterizing an active, organelle-free preparation. 6 figs.

  17. Magnesium in chronic kidney disease: unanswered questions.

    PubMed

    Spiegel, David M

    2011-01-01

    Magnesium ion is critical for life and is integrally involved in cellular function and a key component of normal bone mineral. In health, the kidneys, gastrointestinal tract and bone are responsible for maintaining serum magnesium concentrations in the normal range and magnesium balance. Most clinical disorders involving magnesium, other than chronic kidney disease (CKD), result in hypomagnesemia, either from gastrointestinal or kidney losses. CKD and particularly end-stage kidney disease is the only clinical condition where sustained hypermagnesemia may occur and net magnesium balance may be positive. This review will focus on normal magnesium homeostasis and review the literature in CKD with a particular focus on end-stage kidney disease and the potential role of magnesium as a phosphate binder and in cardiovascular and bone health. A number of small to medium-size interventional trials have shown that magnesium-based compounds can serve as effective phosphate binders. Observational studies suggest that higher serum magnesium concentrations in dialysis patients may improve survival and may slow the progression of vascular calcification. While a few small prospective trials support these findings, no large or long-term studies are available. Magnesium balance remains poorly understood in patients with end-stage kidney disease. While observational and small randomized trials suggest that exogenous administration may be useful as a phosphate binder and may have protective cardiovascular effects in terms of both arrhythmias and vascular calcification, large randomized trials are needed to test these hypotheses. Copyright © 2011 S. Karger AG, Basel.

  18. Magnesium: its role in nutrition and carcinogenesis.

    PubMed

    Blaszczyk, Urszula; Duda-Chodak, Aleksandra

    2013-01-01

    Magnesium (Mg2+) plays a key role in many essential cellular processes such as intermediary metabolism, DNA replication and repair, transporting potassium and calcium ions, cell proliferation together with signalling transduction. Dietary sources rich in magnesium are whole and unrefined grains, seeds, cocoa, nuts, almonds and green leafy vegetables. Hard water is also considered to be an important source of magnesium beneficial to human health. The daily dietary intake of magnesium is however frequently found to be below that recommended in Western countries. Indeed, it is recognised that magnesium deficiency may lead to many disorders of the human body, where for instance magnesium depletion is believed to play an important role in the aetiology of the following; cardiovascular disease (including thrombosis, atherosclerosis, ishaemic heart disease, myocardial infarction, hypertension, arrhythmias and congestive heart failure in human), as well as diabetes mellitus, gastrointestinal (GI) tract disease, liver cirrhosis and diseases of the thyroid and parathyroid glands. Insufficient dietary intake of magnesium may also significantly affect the development and exacerbation ofADHD (Attention Deficit- Hyperactivity Disorder) symptoms in children. The known links between magnesium and carcinogenesis still remain unclear and complex, with conflicting results being reported from many experimental, epidemiological and clinical studies; further knowledge is thus required. Mg2+ ions are enzyme cofactors involved in DNA repair mechanisms that maintain genomic stability and fidelity. Any magnesium deficiencies could thereby cause a dysfunction of these systems to occur leading to DNA mutations. Magnesium deficiency may also be associated with inflammation and increased levels of free radicals where both inflammatory mediators and free radicals so arising could cause oxidative DNA damage and therefore tumour formation. The presented review article now provides a summary

  19. Magnesium in disease: a review with special emphasis on the serum ionized magnesium.

    PubMed

    Sanders, G T; Huijgen, H J; Sanders, R

    1999-01-01

    This review deals with the six main clinical situations related to magnesium or one of its fractions, including ionized magnesium: renal disease, hypertension, pre-eclampsia, diabetes mellitus, cardiac disease, and the administration of therapeutic drugs. Issues addressed are the physiological role of magnesium, eventual changes in its levels, and how these best can be monitored. In renal disease mostly moderate hypermagnesemia is seen; measuring ionized magnesium offers minimal advantage. In hypertension magnesium might be lowered but its measurement does not seem relevant. In the prediction of severe pre-eclampsia, elevated ionized magnesium concentration may play a role, but no unequivocal picture emerges. Low magnesium in blood may be cause for, or consequence of, diabetes mellitus. No special fraction clearly indicates magnesium deficiency leading to insulin resistance. Cardiac diseases are related to diminished magnesium levels. During myocardial infarction, serum magnesium drops. Total magnesium concentration in cardiac cells can be predicted from levels in sublingual or skeletal muscle cells. Most therapeutic drugs (diuretics, chemotherapeutics, immunosuppressive agents, antibiotics) cause hypomagnesemia due to increased urinary loss. It is concluded that most of the clinical situations studied show hypomagnesemia due to renal loss, with exception of renal disease. Keeping in mind that only 1% of the total body magnesium pool is extracellular, no simple measurement of the real intracellular situation has emerged; measuring ionized magnesium in serum has little added value at present.

  20. Magnesium-based implants: a mini-review.

    PubMed

    Luthringer, Bérengère J C; Feyerabend, Frank; Willumeit-Römer, Regine

    2014-01-01

    The goal of this review is to bring to the attention of the readership of Magnesium Research another facet of the importance of magnesium, i.e. magnesium-based biomaterials. A concise history of biomaterials and magnesium are thus presented. In addition, historical and current, clinical magnesium-based applications are presented.

  1. Effects of cerium on key enzymes of carbon assimilation of spinach under magnesium deficiency.

    PubMed

    Yuguan, Ze; Min, Zhou; Luyang, Luo; Zhe, Ji; Chao, Liu; Sitao, Yin; Yanmei, Duan; Na, Li; Fashui, Hong

    2009-11-01

    The mechanism of the fact that cerium improves the photosynthesis of plants under magnesium deficiency is poorly understood. The main aim of the study was to determine the role of cerium in the amelioration of magnesium deficiency effects in CO(2) assimilation of spinach. Spinach plants were cultivated in Hoagland's solution. They were subjected to magnesium deficiency and to cerium chloride administered in the magnesium-present Hoagland's media and magnesium-deficient Hoagland's media. The results showed that the chlorophyll synthesis and oxygen evolution was destroyed, and the activities of Rubisco carboxylasae and Rubisco activase and the expression of Rubisco large subunit (rbcL), Rubisco small subunit (rbcS), and Rubisco activase subunit (rca) were significantly inhibited, then plant growth was inhibited by magnesium deficiency. However, cerium promotes the chlorophyll synthesis, the activities of two key enzymes in CO(2) assimilation, and the expression of rbcL, rbcS, and rca, thus leading to the enhancement of spinach growth under magnesium-deficient conditions.

  2. Method for magnesium sulfate recovery

    DOEpatents

    Gay, Richard L.; Grantham, LeRoy F.

    1987-01-01

    A method of obtaining magnesium sulfate substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is then contacted with a concentrated sulfuric acid under certain prescribed conditions to produce a liquid product and a solid product. The particulate solid product and a minor amount of the liquid is then treated to produce a solid residue consisting essentially of magnesium sulfate substantially free of uranium and having a residual radioactivity level of less than 1000 pCi/gm. In accordance with the preferred embodiment of the invention, a catalyst and an oxidizing agent are used during the initial acid treatment and a final solid residue has a radioactivity level of less than about 50 pCi/gm.

  3. Method for magnesium sulfate recovery

    DOEpatents

    Gay, R.L.; Grantham, L.F.

    1987-08-25

    A method is described for obtaining magnesium sulfate substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7,000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is then contacted with a concentrated sulfuric acid under certain prescribed conditions to produce a liquid product and a solid product. The particulate solid product and a minor amount of the liquid is then treated to produce a solid residue consisting essentially of magnesium sulfate substantially free of uranium and having a residual radioactivity level of less than 1,000 pCi/gm. In accordance with the preferred embodiment of the invention, a catalyst and an oxidizing agent are used during the initial acid treatment and a final solid residue has a radioactivity level of less than about 50 pCi/gm.

  4. Substrate and method for the formation of continuous magnesium diboride and doped magnesium diboride wire

    DOEpatents

    Suplinskas, Raymond J.; Finnemore, Douglas; Bud'ko, Serquei; Canfield, Paul

    2007-11-13

    A chemically doped boron coating is applied by chemical vapor deposition to a silicon carbide fiber and the coated fiber then is exposed to magnesium vapor to convert the doped boron to doped magnesium diboride and a resultant superconductor.

  5. Microstructural Effects on the Spall Properties of ECAE Magnesium and Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Williams, Cyril

    2015-06-01

    Magnesium and magnesium alloys are light weight materials and hence, are being increasingly employed as light armor in military applications. However, because of its limited slip systems (HCP) magnesium and magnesium alloys are relatively brittle as compared to FCC and BCC lattice structures. For this study, the effects of microstructure on the spall properties of magnesium and magnesium alloys processed using Equi-Channel Angular Extrusion (ECAE) were investigated using a 51 mm and 105 mm bore gas guns. Symmetric spall and recovery plate impact experiments were performed at impact velocities ranging from approximately 100 m/s and 400 m/s. Free surface velocity profiles of the shocked samples were obtained using Photonic Doppler Velocimetry (PDV). The spall strength and Hugoniot Elastic Limit (HEL) were extracted from the free surface velocity profiles. In addition, the microstructures of the pre-shocked and post-shocked magnesium and magnesium alloys were acquired using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM).

  6. Low extracellular magnesium ions induce lipid peroxidation and activation of nuclear factor-kappa B in canine cerebral vascular smooth muscle: possible relation to traumatic brain injury and strokes.

    PubMed

    Altura, Burton M; Gebrewold, Asefa; Zhang, Aimin; Altura, Bella T

    2003-05-08

    The present study was designed to test the hypothesis that administration of low extracellular levels of magnesium ions ([Mg(2+)](o)) to primary cultured cerebral vascular smooth muscle cells will cause lipid peroxidation, degradation of IkappaB-alpha, and activation of nuclear transcription factor kappa B (NF-kappaB) in cultured cerebral vascular smooth muscle cells. Low [Mg(2+)](o) (0, 0.15, 0.3 and 0.48 mM) resulted in concentration-dependent rises in malondialdehyde (MDA) in as little as 3 h after exposure to low [Mg(2+)](o), rising to levels 3-12xnormal after 18-24 h; the lower the [Mg(2+)](o), the higher the MDA level. Using electrophoretic mobility shift assays and specific antibodies, low [Mg(2+)](o) caused two DNA-binding proteins (p50, p65) to rise in nuclear extracts in a concentration-dependent manner. High [Mg(2+)](o) (i.e. 4.8 mM) downregulated p50 and p65. Using a rabbit antibody, IkappaB phosphorylation (and degradation) was stimulated by low [Mg(2+)](o) (in a concentration-dependent manner) and inhibited by a low concentration of the NF-kappaB inhibitor, pyrrolidine dithiocarbamate. These new biochemical and molecular data indicate that low [Mg(2+)](o), in concentrations found in the blood of patients, after traumatic brain injury (TBI) and diverse types of strokes, can elicit rapid lipid peroxidation and activation of NF-kappaB in cerebral vascular smooth muscle cells. The present results, when viewed in light of other recently published data, suggest that low [Mg(2+)](o)-induced lipid peroxidation and activation of NF-kappaB play important roles in TBI and diverse types of strokes.

  7. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    SciTech Connect

    Doe, Robert E.; Downie, Craig M.; Fischer, Christopher; Lane, George H.; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin A.; Eaglesham, David

    2016-01-19

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  8. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    DOEpatents

    Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

    2015-10-27

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqeuous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  9. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    SciTech Connect

    Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

    2016-07-26

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  10. Polychlorinated biphenyls-containing electrical insulating oil contaminated soil treatment with calcium and magnesium peroxides.

    PubMed

    Goi, Anna; Viisimaa, Marika; Trapido, Marina; Munter, Rein

    2011-02-01

    Calcium and magnesium peroxides were applied for the treatment of soil contaminated by polychlorinated biphenyls-containing electrical insulating oil (Aroclor 1016). The removal of PCB-containing electrical insulating oil was achieved with the addition of either calcium peroxide or magnesium peroxide alone and dependent on dosages of the chemical. A 21-d treatment of 60% watered soil with the moderate addition (chemical/oil weight ratio of 0.005/1) of either calcium peroxide or magnesium peroxide resulted in nearly complete (96 ± 2%) oil removal, unsubstantial increase in soil pH and almost no changes in oxygen consumption and dehydrogenase activity, making it suitable for the soil decontamination.

  11. Catalysts comprising magnesium and a transition metal

    SciTech Connect

    Bujadoux, K.

    1984-10-09

    A catalyst comprising the product obtained by bringing into contact a compound of magnesium comprising at least one species selected from the group consisting of magnesium monohalides (MgX), halo-magnesium hydrides (HMgX) and magnesium hydride (MgH/sub 2/), X being a halogen and the said species MgX or HMgX being obtained by thermal decomposition of a powdery organo-magnesium halide R/sub 1/MgX wherein R/sub 1/ is an organic radical; and at least one halide of a transistion metal selected from the group consisting of titanium and vanadium, the valency of said metal in said halide being lower than or equal to 3, the quantities being such that the atomic ratio of magnesium to said transistion metal is between 1 and 25, and a catalyst system including the catalyst that is suitable for use in the polymerization of olefins and particularly ethylene.

  12. Lightweight Heat Pipes Made from Magnesium

    NASA Technical Reports Server (NTRS)

    Rosenfeld, John N.; Zarembo, Sergei N.; Eastman, G. Yale

    2010-01-01

    Magnesium has shown promise as a lighter-weight alternative to the aluminum alloys now used to make the main structural components of axially grooved heat pipes that contain ammonia as the working fluid. Magnesium heat-pipe structures can be fabricated by conventional processes that include extrusion, machining, welding, and bending. The thermal performances of magnesium heat pipes are the same as those of equal-sized aluminum heat pipes. However, by virtue of the lower mass density of magnesium, the magnesium heat pipes weigh 35 percent less. Conceived for use aboard spacecraft, magnesium heat pipes could also be attractive as heat-transfer devices in terrestrial applications in which minimization of weight is sought: examples include radio-communication equipment and laptop computers.

  13. Magnesium alloy applications in automotive structures

    NASA Astrophysics Data System (ADS)

    Easton, Mark; Beer, Aiden; Barnett, Matthew; Davies, Chris; Dunlop, Gordon; Durandet, Yvonne; Blacket, Stuart; Hilditch, Tim; Beggs, Peter

    2008-11-01

    The use of magnesium alloys in structural applications has great potential for the lightweighting of transportation vehicles. Research within the CAST Cooperative Research Centre has tackled some of the important issues related to the use of magnesium in structural applications. To this end, a new alloy with extrudability and properties similar to 6000 series aluminum alloys has been developed. Furthermore, a method of laser heating magnesium alloys before self-piercing riveting has enabled high-integrity joining between magnesium components or between magnesium and dissimilar metals. In this paper, new technologies and improved understanding of the deformation behavior of wrought magnesium alloys are discussed in light of key metallurgical features such as alloy composition, grain size, and work hardening rate.

  14. Magnesium ion implantation on a micro/nanostructured titanium surface promotes its bioactivity and osteogenic differentiation function.

    PubMed

    Wang, Guifang; Li, Jinhua; Zhang, Wenjie; Xu, Lianyi; Pan, Hongya; Wen, Jin; Wu, Qianju; She, Wenjun; Jiao, Ting; Liu, Xuanyong; Jiang, Xinquan

    2014-01-01

    As one of the important ions associated with bone osseointegration, magnesium was incorporated into a micro/nanostructured titanium surface using a magnesium plasma immersion ion-implantation method. Hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 30 minutes (Mg30) and hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 60 minutes (Mg60) were used as test groups. The surface morphology, chemical properties, and amount of magnesium ions released were evaluated by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy, and inductively coupled plasma-optical emission spectrometry. Rat bone marrow mesenchymal stem cells (rBMMSCs) were used to evaluate cell responses, including proliferation, spreading, and osteogenic differentiation on the surface of the material or in their medium extraction. Greater increases in the spreading and proliferation ability of rBMMSCs were observed on the surfaces of magnesium-implanted micro/nanostructures compared with the control plates. Furthermore, the osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) genes were upregulated on both surfaces and in their medium extractions. The enhanced cell responses were correlated with increasing concentrations of magnesium ions, indicating that the osteoblastic differentiation of rBMMSCs was stimulated through the magnesium ion function. The magnesium ion-implanted micro/nanostructured titanium surfaces could enhance the proliferation, spreading, and osteogenic differentiation activity of rBMMSCs, suggesting they have potential application in improving bone-titanium integration.

  15. Magnesium ion implantation on a micro/nanostructured titanium surface promotes its bioactivity and osteogenic differentiation function

    PubMed Central

    Wang, Guifang; Li, Jinhua; Zhang, Wenjie; Xu, Lianyi; Pan, Hongya; Wen, Jin; Wu, Qianju; She, Wenjun; Jiao, Ting; Liu, Xuanyong; Jiang, Xinquan

    2014-01-01

    As one of the important ions associated with bone osseointegration, magnesium was incorporated into a micro/nanostructured titanium surface using a magnesium plasma immersion ion-implantation method. Hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 30 minutes (Mg30) and hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 60 minutes (Mg60) were used as test groups. The surface morphology, chemical properties, and amount of magnesium ions released were evaluated by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy, and inductively coupled plasma-optical emission spectrometry. Rat bone marrow mesenchymal stem cells (rBMMSCs) were used to evaluate cell responses, including proliferation, spreading, and osteogenic differentiation on the surface of the material or in their medium extraction. Greater increases in the spreading and proliferation ability of rBMMSCs were observed on the surfaces of magnesium-implanted micro/nanostructures compared with the control plates. Furthermore, the osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) genes were upregulated on both surfaces and in their medium extractions. The enhanced cell responses were correlated with increasing concentrations of magnesium ions, indicating that the osteoblastic differentiation of rBMMSCs was stimulated through the magnesium ion function. The magnesium ion-implanted micro/nanostructured titanium surfaces could enhance the proliferation, spreading, and osteogenic differentiation activity of rBMMSCs, suggesting they have potential application in improving bone-titanium integration. PMID:24940056

  16. Nitric oxide as a mediator of the laxative action of magnesium sulphate.

    PubMed Central

    Izzo, A A; Gaginella, T S; Mascolo, N; Capasso, F

    1994-01-01

    1. Magnesium sulphate was studied for its effects on diarrhoea, fluid secretion, gastrointestinal transit and nitric oxide (NO) synthase activity in rats. 2. At a dose of 2 g kg-1 orally magnesium sulphate produced diarrhoea that was delayed in onset and intensity in a dose-related manner by the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). This was prevented by the NO precursor, L-arginine and the NO donating compound, isosorbide-5-mononitrate (IMN). 3. Nitric oxide synthase activity was stimulated in gut tissue from rats given magnesium sulphate and this was inhibited by L-NAME. Dexamethasone (1 mg kg-1, i.p.), an inhibitor of inducible NO synthase, had no effect on magnesium sulphate-induced diarrhoea. 4. Magnesium sulphate stimulated fluid and electrolyte accumulation in the intestinal lumen; these effects were prevented by L-NAME but not D-NAME. 5. Gastrointestinal transit of a non-absorbable marker (charcoal suspension) was increased by oral magnesium sulphate from a mean value of 54.1% to 72.9% (P < 0.01), and this was prevented by pretreatment with L-NAME. 6. The results demonstrate that oral magnesium sulphate produces diarrhoea in rats by increasing the accumulation of fluid in the intestinal lumen and enhancing flow from the proximal to distal intestine. The mechanism involves release of NO, probably through stimulation of the constitutive form of NO synthase. Whether or not the effects of magnesium sulphate are due to an osmotic action or an intrinsic effect of the magnesium or sulphate ions cannot be determined from these experiments. PMID:7529110

  17. IMPROVED MAGNESIUM OXIDE SLIP CASTING METHOD

    DOEpatents

    Stoddard, S.D.; Nuckolls, D.E.

    1963-12-31

    A process for making an aqueous magnesium oxide slip casting slurry comprising the steps of mixing finely ground fused magnesium oxide with water, milling the slurry for at least 30 hours at a temperature of 2-10 deg C (the low temperature during milling inhibiting the formation of hydrated magnesium oxide), discharging the slurry from the mill, adding hydrochloric acid as a deflocculent, and adding a scum inhibitor is presented. (AEC)

  18. Nanotechnology Corrosion Pretreatment for Magnesium Alloys

    DTIC Science & Technology

    2012-08-29

    Pretreatment for Magnesium Alloys AMS-SAE-M-3171, Type IV Replacement on AZ91D Glycolic Nitrate Pickle (GNP) (1 min) PT-60 (3 min) 0 hr SST 1 4 3 2...Nanotechnology Corrosion Pretreatment for Magnesium Alloys Mr. Jules F. Senske and Mr. Daniel Schmidt Army Research Development and...SUBTITLE Nanotechnology Corrosion Pretreatment for Magnesium Alloys 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d

  19. Magnesium deficiency in a medical ICU population.

    PubMed

    Ryzen, E; Wagers, P W; Singer, F R; Rude, R K

    1985-01-01

    The serum magnesium level was measured in 94 consecutive patients admitted to the medical ICU of Los Angeles County/University of Southern California Medical Center over a 2-month period. Sixty-five percent of patients with serum creatinine concentrations of 1.1 mg/dl or less were hypomagnesemic. Of these, one third had hypocalcemia that was corrected with magnesium supplementation. Physicians should be alert to the high incidence of magnesium deficiency in critically ill patients.

  20. Effects of benzotriazole on the magnesium phosphate coating

    NASA Astrophysics Data System (ADS)

    Zuo, Juan; Guo, Fen; Zhu, Junqiu; Chen, Ajiao; Hu, Yanling; Lin, Changjian; Jiang, Chunhai

    2015-12-01

    Magnesium phosphate coatings are extensively used on carbon steel to improve their corrosion resistance. The effect of benzotriazole on the magnesium phosphate coating was investigated. The phosphate coatings were deposited on carbon steel at different bath temperature, room temperature (RM), 60 °C and 80 °C. The change of crystalline phase, morphology, the sludge weight, bath efficiency factor, and corrosion behavior of the coatings after the addition of benzotriazole (BTAH) were investigated by means of Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and potentiodynamic polarization methods. The adsorption of BTAH during the formation of magnesium phosphate coating was also investigated by means of XPS. The effect of BTAH on the formation of magnesium phosphate coating was discussed. The adsorbed BTAH layer could favor the nucleation of phosphate coating by supplying more nuclei centers which leads to the formation of more compact phosphate coating. Meanwhile, the adsorbed atoms can block the active sites and generate a barrier to reduce the transport of corrosive species to the metal surface and hence improve the corrosion behavior of carbon steels.

  1. Effect of magnesium complexation by fluoroquinolones on their antibacterial properties.

    PubMed

    Lecomte, S; Baron, M H; Chenon, M T; Coupry, C; Moreau, N J

    1994-12-01

    By using infrared and 19F nuclear magnetic resonance spectroscopies, we localized the binding site and measured the affinity of magnesium for six fluoroquinolones. It was proven that magnesium is situated between the ketone and the carboxylate groups. We determined the binding constants for the 1:1 Mg(2+)-drug complex in solution. Sparfloxacin and pefloxacin, with affinity constants (Ka) of (10.1 +/- 0.6) x 10(2) M-1 and (21 +/- 1) x 10(2) M-1, respectively, were the least and the most bound, respectively. The trend of the affinities of the assayed fluoroquinolones for magnesium was correlated with their antimicrobial activities against four bacteria and with their accumulation by these bacteria. The reference strain, Escherichia coli KL16, and two resistant mutants, NalA (gyrase mutation) and NalB (uptake defect), plus Staphylococcus aureus 209P were used. It appeared that, in every case, an impairment of accumulation is responsible for the increase in the MICs observed upon the addition of magnesium.

  2. Effect of magnesium complexation by fluoroquinolones on their antibacterial properties.

    PubMed Central

    Lecomte, S; Baron, M H; Chenon, M T; Coupry, C; Moreau, N J

    1994-01-01

    By using infrared and 19F nuclear magnetic resonance spectroscopies, we localized the binding site and measured the affinity of magnesium for six fluoroquinolones. It was proven that magnesium is situated between the ketone and the carboxylate groups. We determined the binding constants for the 1:1 Mg(2+)-drug complex in solution. Sparfloxacin and pefloxacin, with affinity constants (Ka) of (10.1 +/- 0.6) x 10(2) M-1 and (21 +/- 1) x 10(2) M-1, respectively, were the least and the most bound, respectively. The trend of the affinities of the assayed fluoroquinolones for magnesium was correlated with their antimicrobial activities against four bacteria and with their accumulation by these bacteria. The reference strain, Escherichia coli KL16, and two resistant mutants, NalA (gyrase mutation) and NalB (uptake defect), plus Staphylococcus aureus 209P were used. It appeared that, in every case, an impairment of accumulation is responsible for the increase in the MICs observed upon the addition of magnesium. Images PMID:7695267

  3. Surface characterization and cytotoxicity response of biodegradable magnesium alloys.

    PubMed

    Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem

    2015-04-01

    Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS.

  4. Lewis Acid-free and Phenolate-based Magnesium Electrolyte for Rechargeable Magnesium Batteries

    SciTech Connect

    Pan, Baofei; Zhang, Junjie; Huang, Jinhua; Vaughey, John T.; Zhang, Lu; Han, Sang Don; Zhang, Zhengcheng; Liao, Chen

    2015-03-02

    A novel Lewis acid-free and phenolate-based magnesium electrolyte has been established. The excellent reversibility and stability of this electrolyte in battery cycling render this novel Lewis acid-free synthetic approach as a highly promising alternative for the development of highly anodically stable magnesium electrolytes for rechargeable magnesium batteries.

  5. 21 CFR 862.1495 - Magnesium test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of...

  6. 21 CFR 862.1495 - Magnesium test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels...

  7. 21 CFR 862.1495 - Magnesium test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of...

  8. 21 CFR 862.1495 - Magnesium test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of...

  9. 21 CFR 862.1495 - Magnesium test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of...

  10. Magnesium enrichment and distribution in plants.

    PubMed

    Courtois, D; Kastenmayer, P; Clough, J; Vigo, M; Sabatier, M; Arnaud, M J

    2003-12-01

    Food products enriched with stable isotopes are used in nutrition to study the metabolic fate of nutrients in humans. This study reports on the labeling of green beans, white beans, soybeans and wheat with a stable isotope of magnesium (25Mg) obtained in greenhouse conditions for further studies on magnesium bioavailability. Soybean and green bean are the most efficient plant species to obtain large amounts of edible parts rapidly with a minimum loss of labeled Mg in other parts of the plants. The results obtained showed that a relatively high percentage of the magnesium found in seeds (grains/beans) can come from the redistribution of magnesium previously accumulated in other organs.

  11. Wide Strip Casting Technology of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Park, W.-J.; Kim, J. J.; Kim, I. J.; Choo, D.

    Extensive investigations relating to the production of high performance and low cost magnesium sheet by strip casting have been performed for the application to automotive parts and electronic devices. Research on magnesium sheet production technology started in 2004 by Research Institute of Industrial Science and Technology (RIST) with support of Pohang Iron and Steel Company (POSCO). POSCO has completed the world's first plant to manufacture magnesium coil. Another big project in order to develop wide strip casting technology for the automotive applications of magnesium sheets was started in succession.

  12. Evidence for bicarbonate-dependent magnesium reabsorption.

    PubMed

    Hartmann, A; Langberg, H; Dibona, G; Kiil, F

    1983-01-01

    During ethacrynic acid administration about 50% of the filtered load of magnesium is reabsorbed. To examine whether the remaining component of magnesium reabsorption is bicarbonate-dependent, i.e. varies with factors known to alter passive reabsorption, experiments were performed in anesthetized dogs. During ethacrynic acid administration MgCl2 infusion raised the plasma concentration of magnesium (PMg) from 0.64 +/- 0.05 to 3.06 +/- 0.27 mM and doubled magnesium reabsorption. The infusion of acetazolamide at high PMg reduced bicarbonate reabsorption by 41 +/- 3% and magnesium reabsorption by 31 +/- 16%. When plasma pH was reduced to 7.04 +/- 0.02 and increased to 7.83 +/- 0.02 by altering PCO2 at a constant plasma bicarbonate concentration of 31.2 +/- 0.8 mM, magnesium and bicarbonate reabsorption were correlated (r = 0.82). The infusion of mannitol, which acts by reducing passive solute transport without affecting bicarbonate reabsorption, halved magnesium reabsorption. By combining mannitol and acetazolamide infusions, only 6 +/- 4% of the filtered magnesium was still reabsorbed. These results indicate that the reabsorption of magnesium remaining after the infusion of ethacrynic acid and after raising PMg varies with changes in PCO2 and is inhibited by the infusion of acetazolamide and mannitol as expected for bicarbonate-dependent passive reabsorption.

  13. Magnesium prevents β-glycerophosphate-induced calcification in rat aortic vascular smooth muscle cells.

    PubMed

    Bai, Yaling; Zhang, Junxia; Xu, Jinsheng; Cui, Liwen; Zhang, Huiran; Zhang, Shenglei; Feng, Xunwei

    2015-07-01

    Vascular calcification (VC), in which high serum phosphate plays a critical role, is one major problem in patients with chronic kidney disease. Clinical studies report that magnesium has a protective effect on VC. However, the studies regarding the impact of high serum magnesium on VC at a cellular level are few and require further investigation. Therefore, the present study explored the effect of magnesium on calcification induced by β-glycerophosphate (BGP) in rat aortic vascular smooth muscle cells (RAVSMCs). In the present study, the addition of magnesium decreased calcium deposition, which was increased by BGP. Higher magnesium levels inhibited BGP-induced alkaline phosphatase (ALP) activity and decreased the expression of core-binding factor α-1 (Cbfα1). In conclusion, higher magnesium levels prevented BGP-induced calcification in RAVSMCs and inhibited the expression of Cbfα1 and ALP. Thus, magnesium is influencing the expression of Cbfα1 and ALP associated with VC and may have the potential to serve as a role for VC in clinical situations.

  14. Magnesium prevents β-glycerophosphate-induced calcification in rat aortic vascular smooth muscle cells

    PubMed Central

    BAI, YALING; ZHANG, JUNXIA; XU, JINSHENG; CUI, LIWEN; ZHANG, HUIRAN; ZHANG, SHENGLEI; FENG, XUNWEI

    2015-01-01

    Vascular calcification (VC), in which high serum phosphate plays a critical role, is one major problem in patients with chronic kidney disease. Clinical studies report that magnesium has a protective effect on VC. However, the studies regarding the impact of high serum magnesium on VC at a cellular level are few and require further investigation. Therefore, the present study explored the effect of magnesium on calcification induced by β-glycerophosphate (BGP) in rat aortic vascular smooth muscle cells (RAVSMCs). In the present study, the addition of magnesium decreased calcium deposition, which was increased by BGP. Higher magnesium levels inhibited BGP-induced alkaline phosphatase (ALP) activity and decreased the expression of core-binding factor α-1 (Cbfα1). In conclusion, higher magnesium levels prevented BGP-induced calcification in RAVSMCs and inhibited the expression of Cbfα1 and ALP. Thus, magnesium is influencing the expression of Cbfα1 and ALP associated with VC and may have the potential to serve as a role for VC in clinical situations. PMID:26171172

  15. Laser-induced Magnesium Production from Magnesium Oxide for Renewable Magnesium Energy Cycle.

    NASA Astrophysics Data System (ADS)

    Liao, Shi-Hua; Yabe, Takashi; Baasandash, Choijil; Sato, Yuji; Ichikawa, Masashi; Nakatsuka, Masashi; Fukushima, Chika; Uchida, Shigeaki; Ohkubo, Tomomasa

    2010-10-01

    We succeeded in reducing magnesium [Mg] from magnesium oxide [MgO] by laser irradiation. The laser-induced vapor temperature was measured to be approximately 5000 K on the irradiating spot, where MgO separated into Mg and oxygen [O] atoms through thermal dissociation. The Mg vapor was intercepted a cooper plate, forming solid deposits on it. However, the presence of oxygen, resulting from MgO dissociation, leads to Mg oxidization in the course of vapor cooling. The deoxidization process results in lower Mg fraction in the deposits and degrades energy recovery efficiency from laser irradiation. To quench this recombination, we also employed silicon as reducing agents to capture oxygen in favor of Mg extraction. In these experiments, the molar ratio effect (MgO:Si = 1:0-1) on the magnesium fractions and energy efficiencies were measured by means of a chemical reaction. The maximal energy efficiency, %, was obtained at the ratio of MgO:Si = 1:0.5. This ratio is lower than that of the Pidgeon process with Mg:Si = 1:1 resulting in a lower energy efficiency of %. This implies laser-induced Mg production is a economical process of using reducing agents with large throughput. The usage of laser radiation generated from solar energy for Mg metallurgy will significantly reduce CO2 emission.

  16. Magnesium carbonate precipitate strengthened aerobic granules.

    PubMed

    Lee, Duu-Jong; Chen, Yu-You

    2015-05-01

    Aerobic granules were precipitated internally with magnesium carbonate to enhance their structural stability under shear. The strengthened granules were tested in continuous-flow reactors for 220 days at organic loadings of 6-39 kg/m(3)/day, hydraulic retention times of 0.44-19 h, and temperatures of 10 or 28°C. The carbonate salt had markedly improved the granule strength without significant changes in granule morphology or microbial communities (with persistent strains Streptomyces sp., Rhizobium sp., Brevundimonas sp., and Nitratireductor sp.), or sacrifice in biological activity for organic degradation. MgCO3 precipitated granules could be used in continuous-flow reactor for wastewater treatment at low cost and with easy processing efforts.

  17. Effect of Hypoxia on the Calcium and Magnesium Content, Lipid Peroxidation Level, and Ca2+-ATPase Activity of Syncytiotrophoblast Plasma Membranes from Placental Explants

    PubMed Central

    Chiarello, Delia I.; Benzo, Zully; Piñero, Sandy; Botana, Desirée; Abad, Cilia

    2014-01-01

    In the current study the possible relationship between the Ca2+/Mg2+ ratio of human syncytiotrophoblast plasma membranes and their lipid peroxidation and Ca2+-ATPase activity was determined. Syncytiotrophoblast plasma membranes of placental explants cultured under hypoxia increased their lipid peroxidation and Ca2+ content, diminished their Ca2+-ATPase activity, and kept their Mg2+ content unchanged. Membranes preincubated with different concentrations of Ca2+ increased their Ca2+ content without changes in their Mg2+ content. There is a direct relationship between Ca2+ content and lipid peroxidation of the membranes, as well as an inverse relationship between their Ca2+ content and Ca2+-ATPase activity. On the contrary, preincubation of membranes with different concentrations of Mg2+ showed a higher Mg2+ content without changing their lipid peroxidation and Ca2+-ATPase activity. Explants cultured under hypoxia in the presence of 4 mM MgSO4 showed similar values of lipid peroxidation and Ca2+-ATPase activity of their membranes compared to those of explants cultured under normoxia. Increased Ca2+ content of the membranes by interacting with negatively charged phospholipids could result in destabilizing effects of the membrane structure, exposing hydrocarbon chains of fatty acids to the action of free radicals. Mg2+ might exert a stabilizing effect of the membranes, avoiding their exposure to free radicals. PMID:25180187

  18. Effect of hypoxia on the calcium and magnesium content, lipid peroxidation level, and Ca²⁺-ATPase activity of syncytiotrophoblast plasma membranes from placental explants.

    PubMed

    Chiarello, Delia I; Marín, Reinaldo; Proverbio, Fulgencio; Benzo, Zully; Piñero, Sandy; Botana, Desirée; Abad, Cilia

    2014-01-01

    In the current study the possible relationship between the Ca(2+)/Mg(2+) ratio of human syncytiotrophoblast plasma membranes and their lipid peroxidation and Ca(2+)-ATPase activity was determined. Syncytiotrophoblast plasma membranes of placental explants cultured under hypoxia increased their lipid peroxidation and Ca(2+) content, diminished their Ca(2+)-ATPase activity, and kept their Mg(2+) content unchanged. Membranes preincubated with different concentrations of Ca(2+) increased their Ca(2+) content without changes in their Mg(2+) content. There is a direct relationship between Ca(2+) content and lipid peroxidation of the membranes, as well as an inverse relationship between their Ca(2+) content and Ca(2+)-ATPase activity. On the contrary, preincubation of membranes with different concentrations of Mg(2+) showed a higher Mg(2+) content without changing their lipid peroxidation and Ca(2+)-ATPase activity. Explants cultured under hypoxia in the presence of 4 mM MgSO4 showed similar values of lipid peroxidation and Ca(2+)-ATPase activity of their membranes compared to those of explants cultured under normoxia. Increased Ca(2+) content of the membranes by interacting with negatively charged phospholipids could result in destabilizing effects of the membrane structure, exposing hydrocarbon chains of fatty acids to the action of free radicals. Mg(2+) might exert a stabilizing effect of the membranes, avoiding their exposure to free radicals.

  19. Understanding the effect of magnesium ion concentration on the catalytic activity of ribonuclease H through computation: does a third metal binding site modulate endonuclease catalysis?

    PubMed

    Ho, Ming-Hsun; De Vivo, Marco; Dal Peraro, Matteo; Klein, Michael L

    2010-10-06

    Ribonuclease H (RNase H) belongs to the nucleotidyl-transferase superfamily and hydrolyzes the phosphodiester linkage on the RNA strand of a DNA/RNA hybrid duplex. Due to its activity in HIV reverse transcription, it represents a promising target for anti-HIV drug design. While crystallographic data have located two ions in the catalytic site, there is ongoing debate concerning just how many metal ions bound at the active site are optimal for catalysis. Indeed, experiments have shown a dependency of the catalytic activity on the Mg(2+) concentration. Moreover, in RNase H, the glutamate residue E188 has been shown to be essential for full enzymatic activation, regardless of the Mg(2+) concentration. The catalytic center is known to contain two Mg(2+) ions, and E188 is not one of the primary metal ligands. Herein, classical molecular dynamics (MD) simulations are employed to study the metal-ligand coordination in RNase H at different concentration of Mg(2+). Importantly, the presence of a third Mg(2+) ion, bound to the second-shell ligand E188, is a persistent feature of the MD simulations. Free energy calculations have identified two distinct conformations, depending on the concentration of Mg(2+). At standard concentration, a third Mg(2+) is found in the catalytic pocket, but it does not perturb the optimal RNase H active conformation. However, at higher concentration, the third Mg(2+) ion heavily perturbs the nucleophilic water and thereby influences the catalytic efficiency of RNase H. In addition, the E188A mutant shows no ability to engage additional Mg(2+) ions near the catalytic pocket. This finding likely explains the decrease in catalytic activity of E188A and also supports the key role of E188 in localizing the third Mg(2+) ion at the active site. Glutamate residues are commonly found surrounding the metal center in the endonuclease family, which suggests that this structural motif may be an important feature to enhance catalytic activity. The present MD

  20. The Application of Magnesium(I) Compounds to Energy Storage Materials - Phase 2

    DTIC Science & Technology

    2013-06-24

    1 Final Report The Application of Magnesium (I) Compounds to Energy Storage Materials - Phase 2 Principal Investigator: Professor Cameron...TYPE Final 3. DATES COVERED 01-10-2011 to 31-05-2013 4. TITLE AND SUBTITLE The Application of Magnesium (I) Compounds to Energy Storage Materials...unique properties of these systems in an exploration of their applicability to synthesis, small molecule activation, catalysis, hydrogen storage and

  1. Mechanochemistry of magnesium oxide revisited: facile derivatisation of pharmaceuticals using coordination and supramolecular chemistry.

    PubMed

    Chow, Ernest H H; Strobridge, Fiona C; Friscić, Tomislav

    2010-09-14

    Liquid-assisted grinding allows the rapid, waste-free and one-pot synthesis of a variety of magnesium drug derivatives directly from the excipient MgO; such reactivity is relevant for the behaviour of ibuprofen formulations involving MgO and can be used for oxide-based mechanosynthesis of metal-organic salts, discrete complexes and carboxylate clusters involving magnesium and pharmaceutically active ingredients.

  2. Interdiffusion of magnesium and iron dopants in gallium nitride

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Tomonobu; Kitatani, Takeshi; Terano, Akihisa; Mochizuki, Kazuhiro

    2015-03-01

    The interdiffusion of magnesium and iron in gallium nitride (GaN), i.e., magnesium-iron interdiffusion, was investigated using magnesium-doped GaN layers on iron-doped GaN substrates. The investigation confirms that the magnesium-iron interdiffusion strongly depends on the concentrations of magnesium and iron, that is, it occurs when the iron and magnesium concentrations are high (magnesium: 2 × 1020 cm-3 iron: 2 × 1019 cm-3). It also confirms that diffused iron in the magnesium-doped GaN layer acts as a nonradiative recombination center in GaN.

  3. The effect of feeding with a tryptophan-free amino acid mixture on rat liver magnesium ion-activated deoxyribonucleic acid-dependent ribonucleic acid polymerase

    PubMed Central

    Henderson, A. R.

    1970-01-01

    1. The Widnell & Tata (1966) assay method for Mg2+-activated DNA-dependent RNA polymerase was used for initial-velocity determinations of rat liver nuclear RNA polymerase. One unit (U) of RNA polymerase was defined as that amount of enzyme required for 1 mmol of [3H]GMP incorporation/min at 37°C. 2. Colony fed rats were found to have a mean RNA polymerase activity of 65.9μU/mg of DNA and 18h-starved rats had a mean activity of 53.2μU/mg of DNA. Longer periods of starvation did not significantly decrease RNA polymerase activity further. 3. Rats that had been starved for 18h were used for all feeding experiments. Complete and tryptophan-deficient amino acid mixtures were given by stomach tube and the animals were killed 15–120min later. The response of RNA polymerase to the feeding with the complete amino acid mixture was rapid and almost linear over the first hour of feeding, resulting in a doubling of activity. The activity was still elevated above the starvation value at 120min after feeding. The tryptophan-deficient amino acid mixture produced a much less vigorous response about 45min after the feeding, and the activity had returned to the starvation value by 120min after the feeding. 4. The response of RNA polymerase to the feeding with the complete amino acid mixture was shown to occur within a period of less than 5min to about 10min after the feeding. 5. Pretreatment of the animals with puromycin or cycloheximide was found to abolish the 15min RNA polymerase response to the feeding with the complete amino acid mixture, but the activity of the controls was unaffected. 6. The characteristics of the RNA polymerase from 18h-starved animals and animals fed with the complete or incomplete amino acid mixtures for 1h were examined. The effects of Mg2+ ions, pH, actinomycin D and nucleoside triphosphate omissions were determined. The [Mg2+]– and pH–activity profiles of the RNA polymerase from the animal fed with the complete mixture appeared to differ from

  4. Association between magnesium status, oxidative stress and inflammation in preeclampsia: A case-control study.

    PubMed

    de Sousa Rocha, Vivianne; Della Rosa, Fernanda Brunacci; Ruano, Rodrigo; Zugaib, Marcelo; Colli, Célia

    2015-12-01

    Preeclampsia is responsible for more than one-third of all maternal deaths in Brazil. The objectives of the present study were to evaluate magnesium status and its association with oxidative stress and inflammation in preeclamptic women, and to identify the predictor variables of the disorder. The study population consisted of 36 women divided into preeclamptic (n = 18) and control groups (n = 18). The preeclamptic group included women (≥20 weeks of pregnancy) with arterial pressure ≥ 140/90 mmHg and proteinuria >0.3 g/24 h, while the control group comprised pregnant women with no clinical/obstetric complications. Magnesium intake was assessed via a food frequency questionnaire validated for pregnant women in Brazil. Plasma, erythrocyte and urinary magnesium levels were determined by flame atomic absorption spectroscopy, while oxidative stress and inflammatory markers were assessed using standard protocols. Logistic regression analysis was used to identify the predictors of preeclampsia. Preeclamptic and control groups were similar with respect to magnesium intake and urinary excretion, while plasma and erythrocyte magnesium concentrations were higher in the former group. Plasma magnesium was positively correlated with catalase and glutathione peroxidase activities and with concentrations of interleukin-6 and tumor necrosis factor alpha. Regression analysis showed that plasma magnesium and urinary 8-isoprostane were associated with preeclampsia. Magnesium status appears to result from homeostatic imbalance and physiological alterations typical of preeclampsia. Increased plasma magnesium and decreased urinary 8-isoprostane were considered predictors of preeclampsia. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  5. Quantitative analysis of EEG effects following experimental marginal magnesium and boron deprivation.

    PubMed

    Penland, J G

    1995-12-01

    Magnesium (115 and 315 mg/d) and boron (0.23 and 3.23 mg/d) were fed in a double-blind Latin squares design to 13 healthy postmenopausal women (aged 50-78 years) living on a metabolic unit. An eight-channel electroencephalogram (EEG) was recorded during the last week of each of four 6-week dietary periods. Power and coherence measures were determined for each of four EEG frequency bands: delta (1-3 Hz), theta (4-7 Hz), alpha (8-12 Hz), and beta (13-18 Hz). Compared to high dietary magnesium, the low magnesium intake increased total power in the frontal regions and right temporal and parietal regions and resulted in frequency-specific increases in left occipital delta power, theta power in all but the left temporal region, alpha power in the right frontal and right temporal regions, and beta power in the frontal regions. The proportion of theta to total power in the parietal regions also increased with the low magnesium intake. While magnesium effects were observed primarily during eyes-closed conditions, effects of dietary boron on EEG power were found only during eyes-open conditions. Relative to high dietary boron, the low boron intake increased delta power in the left parietal and left occipital regions, increased the proportion of delta to total power in the frontal regions, and decreased relative right frontal theta, right frontal alpha, and left frontal beta power. Additional magnesium and boron effects were evident in the measures of EEG coherence. Thus relatively short periods of marginal magnesium and boron deprivation can affect brain function in healthy older women. The findings extend previous qualitative observations of increased CNS activity following severe magnesium deprivation and deficiency to cases of experimentally induced marginal magnesium deficiency, and verify CNS hyperexcitability by quantitative analysis of the EEG.

  6. The protein tyrosine phosphatase PRL-2 interacts with the magnesium transporter CNNM3 to promote oncogenesis.

    PubMed

    Hardy, S; Uetani, N; Wong, N; Kostantin, E; Labbé, D P; Bégin, L R; Mes-Masson, A; Miranda-Saavedra, D; Tremblay, M L

    2015-02-19

    The three PRL (phosphatases of regenerating liver) protein tyrosine phosphatases (PRL-1, -2 and -3) have been identified as key contributors to metastasis in several human cancers, yet the molecular basis of their pro-oncogenic property is unclear. Among the subfamily of PRL phosphatases, overexpression of PRL-2 in breast cancer cells has been shown to promote tumor growth by a mechanism that remains to be uncovered. Here we show that PRL-2 regulates intracellular magnesium levels by forming a functional heterodimer with the magnesium transporter CNNM3. We further reveal that CNNM3 is not a phosphorylated substrate of PRL-2, and that the interaction occurs through a loop unique to the CBS pair domains of CNNM3 that exists only in organisms having PRL orthologs. Supporting the role of PRL-2 in cellular magnesium transport is the observation that PRL-2 knockdown results in a substantial decrease of cellular magnesium influx. Furthermore, in PRL-2 knockout mice, serum magnesium levels were significantly elevated as compared with control animals, indicating a pivotal role for PRL-2 in regulating cellular magnesium homeostasis. Although the expression levels of CNNM3 remained unchanged after magnesium depletion of various cancer cell lines, the interaction between endogenous PRL-2 and CNNM3 was markedly increased. Importantly, xenograft tumor assays with CNNM3 and a mutant form that does not associate with PRL-2 confirm that CNNM3 is itself pro-oncogenic, and that the PRL-2/CNNM3 association is important for conferring transforming activities. This finding is further confirmed from data in human breast cancer tissues showing that CNNM3 levels correlate positively with both PRL-2 expression and the tumor proliferative index. In summary, we demonstrate that oncogenic PRL-2 controls tumor growth by modulating intracellular magnesium levels through binding with the CNNM3 magnesium transporter.

  7. The effects of oral magnesium hydroxide administration on rumen fluid in cattle.

    PubMed

    Smith, Geoffrey W; Correa, Maria T

    2004-01-01

    This study was conducted to determine the effects of oral magnesium hydroxide administration on rumen fluid in cattle. Six lactating Holstein cows (4-7 years of age) with rumen fistulas were studied. Cattle were randomly assigned to receive boluses of magnesium hydroxide (162 g) or a powdered form (450 g dissolved in 3.5 L of water) PO daily for 3 days. Analysis of rumen fluid, blood gas tensions, and pH and measurement of serum magnesium concentrations were conducted daily. The study was discontinued after 72 hours, or sooner if rumen pH exceeded 8.0. After at least 3 weeks, the study was repeated with each cow receiving the other form of magnesium hydroxide (powder or bolus). Compared with baseline rumen pH (mean +/- SD: 6.22 +/- 0.28), magnesium hydroxide boluses caused a significant increase (P < .05) in rumen pH after 48 (7.27 +/- 0.11) and 72 (8.01 +/- 0.16) hours of administration, whereas the powdered form caused a significant increase (P < .05) in rumen pH after 24 (7.54 +/- 0.19) and 48 (8.43 +/- 0.22) hours of administration. Both the powdered and bolus forms of magnesium hydroxide decreased rumen protozoal numbers and increased methylene blue reduction times compared with baseline values. There was no change in blood pH, bicarbonate, or base excess values. Serum magnesium concentrations were significantly increased (P < .05) in cows that received the magnesium hydroxide powder. The results of this study indicate that magnesium hydroxide has a potent alkalinizing effect on rumen pH and significantly decreases rumen microbial activity.

  8. Iatrogenic magnesium toxicity following intravenous infusion of magnesium sulfate: risks and strategies for prevention

    PubMed Central

    Cavell, Gillian F; Bryant, Catherine; Jheeta, Seetal

    2015-01-01

    A 65-year-old man being treated with radiotherapy and chemotherapy for recurrent colonic adenocarcinoma was admitted for management of hypokalaemia and hypomagnesaemia secondary to diarrhoea. He was treated with intravenous infusions of potassium chloride and magnesium sulfate. Following an infusion of magnesium sulfate, he experienced a sudden neurological deterioration. A CT of the head revealed no haemorrhage or evidence of acute ischaemic injury. Results of serum biochemistry later that day revealed an elevated magnesium level. Iatrogenic magnesium toxicity was suspected. Further discussions between the pharmacist and ward staff confirmed that a medication error had been made in the preparation of the infusion resulting in an overdose of intravenous magnesium. PMID:26231187

  9. Effect of magnesium infusion on thoracic epidural analgesia

    PubMed Central

    Gupta, Sampa Dutta; Mitra, Koel; Mukherjee, Maitreyee; Roy, Suddhadeb; Sarkar, Aniruddha; Kundu, Sudeshna; Goswami, Anupam; Sarkar, Uday Narayan; Sanki, Prakash; Mitra, Ritabrata

    2011-01-01

    Introduction: Patients of lung volume reduction surgery (LVRS) having an ASA status III or more are likely to be further downgraded by surgery to critical levels of pulmonary function. Aim: To compare the efficacy of thoracic epidural block with (0.125%) bupivacaine, fentanyl combination and (0.125%) bupivacaine, fentanyl combination with adjunctive intravenous magnesium infusion for the relief of postoperative pain in patients undergoing LVRS. Methods: Patients were operated under general anesthesia. Thirty minutes before the anticipated completion of skin closure in both groups, (Group A and Group B) 7 ml of (0.125%) bupivacaine calculated as 1.5 ml/thoracic segment space for achieving analgesia in dermatomes of T4, T5, T6, T7, and T8 segments, along with fentanyl 50 μg (0.5 ml), was administered through the catheter, activating the epidural block, and the time was noted. Thereafter, in patients of Group A, magnesium sulfate injection 30 mg/kg i.v. bolus was followed by infusion of magnesium sulfate at 10 mg/kg/hr and continued up to 24 hours. Group B was treated as control. Results and Analysis: A significant increase in the mean and maximum duration of analgesia in Group A in comparison with Group B (P<0.05) was observed. Total epidural dose of fentanyl and bupivacaine required in Group A was significantly lower in comparison with Group B in 24 hours. Discussion: Requirement of total doses of local anesthetics along with opioids could be minimized by magnesium infusion; therefore, the further downgradation of patients of LVRS may be prevented. Conclusion: Intravenous magnesium can prolong opioid-induced analgesia while minimizing nausea, pruritus, and somnolence. PMID:21655018

  10. Deformation behavior and microstructure evolution of wrought magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wang, Shouren; Song, Linghui; Kang, Sukbong; Cho, Jaehyung; Wang, Yingzi

    2013-05-01

    There are many researches on the deformation behavior of wrought magnesium alloys, such as AZ31, AZ80, AZ91, and ZK60 magnesium alloys at different temperatures and strain rates, but few of them focuses on the deformation behavior of AZ41M and ZK60M alloys, especially under the twin-roll casting (TRC) state. Meanwhile, the existing researches only focus on the grain refinement law of the magnesium alloys under deformation conditions, the deformation mechanism has not been revealed yet. The hot compression behavior of AZ41M and ZK60M magnesium alloys under the temperature and strain rate ranges of 250-400 °C and 0.001-1 s-1 are studied by thermal simulation methods using Gleeble 1500 machine and virtual simulation using finite element analysis software. Simulation results show that sine hyperbolic law is the most suitable flow stress model for wider deformation conditions. The most reasonable selected deformation conditions of ZK60M alloy is 350 °C/0.1 s-1 for TRC and 350 °C/1 s-1 for conventional casting (CC), while AZ41M alloy is 300 °C/0.01 s-1 for TRC and 350 °C/0.1 s-1 for CC. Deformation behavior and dynamic recrystallization (DRX) mechanism of them are analyzed at the same deformation conditions. The microstructures of AZ41M and ZK60M alloys are observed at different deformed conditions by optical microscopy (OM) and electron back scatter diffraction (EBSD) and it reveals the flow behavior and deformation mechanism of them. Working harden and work soften contribute to the activation of basal, non-basal slip systems which promote DRX. The proposed research reveals the deformation behavior and mechanism of the AZ41M and ZK 60M magnesium alloys and concludes their optimized deformation parameters and processes and provides a theory basis for their manufacturing and application.

  11. 21 CFR 331.11 - Listing of specific active ingredients.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... (5) Dihydroxyaluminum sodium carbonate. (b) Bicarbonate-containing active ingredients: Bicarbonate... aluminosilicates. (4) Magnesium carbonate. (5) Magnesium glycinate. (6) Magnesium hydroxide. (7) Magnesium oxide... old and 100 mEq. of bicarbonate ion for persons 60 years or older. (2) Sodium potassium tartrate. (k...

  12. Summary of "Magnesium Vision 2020: A North American Automotive Strategic Vision for Magnesium"

    NASA Astrophysics Data System (ADS)

    Cole, Gerald S.

    This paper summarizes the monograph, "Magnesium Vision 2020. A North American Automotive Strategic Vision for Magnesium"1 prepared under the auspices of the United States Automotive Materials Partnership The objective was to understand the infrastructural and technical challenge that can increase the use of magnesium in the automotive industry. One hundred sixty three (163) Research and Technology Development Themes (RTDTs), or RTD projects were developed that addressed issues of corrosion, fastening, and processing-other-than-high pressure die casting to produce automotive magnesium parts. A major problem identified in the study is the limited ability of the current magnesium industrial infrastructure to supply RTD and implementation-ready automotive magnesium components. One solution is to create a magnesium cyber center wrhere globally networked experts would be able to innovate in process and product development, model metalworking and non-HPDC foundry processes, and integrate theoretical predictions/models of metallurgical structure with component function.

  13. Intraoperative Magnesium Administration Does Not Improve Neurocognitive Function Following Cardiac Surgery

    PubMed Central

    Mathew, Joseph P.; White, William D.; Schinderle, David B.; Podgoreanu, Mihai V.; Berger, Miles; Milano, Carmelo A.; Laskowitz, Daniel T.; Stafford-Smith, Mark; Blumenthal, James A.; Newman, Mark F.

    2014-01-01

    Background and Purpose Neurocognitive decline occurs frequently after cardiac surgery and persists in a significant number of patients. Magnesium is thought to provide neuroprotection through preservation of cellular energy metabolism, blockade of the N-methyl-D-aspartate receptor, diminution of the inflammatory response, and inhibition of platelet activation. We therefore hypothesized that intraoperative magnesium administration would decrease postoperative cognitive impairment. Methods Following IRB approval, 389 patients undergoing cardiac surgery were enrolled into this prospective, randomized, double-blinded placebo controlled clinical trial. Subjects were randomized to receive: 1) Magnesium as a 50 mg/kg bolus followed by another 50 mg/kg infusion over 3 hours or 2) Placebo bolus and infusion. Cognitive function was assessed preoperatively and again at 6 weeks postoperatively using a standardized test battery. Mean CD11b fluorescence and percentage of platelets expressing CD62P, markers of leukocyte and platelet activation respectively, were assessed by flow cytometry as a secondary outcome. The effect of magnesium on postoperative cognition was tested using multivariable regression modeling, adjusting for age, years of education, baseline cognition, gender, race and weight. Results Among the 389 allocated subjects (Magnesium: N=198; Placebo: N=191), the incidence of cognitive deficit in the magnesium group was 44.4% compared to 44.9% in the placebo group (p=0.93). The cognitive change score and platelet and leukocyte activation were also not different between groups. Multivariable analysis revealed a marginal interaction between treatment group and weight, such that heavier subjects receiving magnesium were less likely to suffer cognitive deficit (p=0.06). Conclusions Magnesium administered intravenously during cardiac surgery does not reduce postoperative cognitive dysfunction. Clinical Trials Registration–URL http://clinicaltrials.gov/ Unique identifier

  14. Magnesium: Is It a Viable Option?

    DTIC Science & Technology

    2012-08-01

    strike - High alkalinity • Magnesium strike – High alkalinity • Electroless Nickel - formulated to prevent attach of magnesium. Success Stories...ionic palladium, palladium reducer, electroless copper and electroless nickel. The initial results were encouraging: We were able to Get the parts

  15. An automated method for serum magnesium estimation

    PubMed Central

    Whitmore, D. N.; Evans, D. I. K.

    1964-01-01

    An automated method for magnesium determination in serum is described using conventional AutoAnalyser equipment. The method gives results comparable with those obtained by the flame photometer. The method may prove particularly useful with subnormal serum magnesium levels. PMID:14227433

  16. Nanostructured magnesium increases bone cell density

    NASA Astrophysics Data System (ADS)

    Weng, Lucy; Webster, Thomas J.

    2012-12-01

    Magnesium has attracted some attention in orthopedics due to its biodegradability and mechanical properties. Since magnesium is an essential natural mineral for bone growth, it can be expected that as a biomaterial, it would support bone formation. However, upon degradation in the body, magnesium releases OH- which results in an alkaline pH that can be detrimental to cell density (for example, osteoblasts or bone forming cells). For this reason, modification of magnesium may be necessary to compensate for such detrimental effects to cells. This study created biologically inspired nanoscale surface features on magnesium by soaking magnesium in various concentrations of NaOH (from 1 to 10 N) and for various periods of time (from 10 to 30 min). The results provided the first evidence of increased roughness, surface energy, and consequently greater osteoblast adhesion, after 4 h as well as density up to 7 days on magnesium treated with any concentration of NaOH for any length of time compared to untreated controls. For these reasons, this study suggests that soaking magnesium in NaOH could be an inexpensive, simple and effective manner to promote osteoblast functions for numerous orthopedic applications and, thus, should be further studied.

  17. Magnesium in obstetric anesthesia and intensive care.

    PubMed

    Kutlesic, Marija S; Kutlesic, Ranko M; Mostic-Ilic, Tatjana

    2017-02-01

    Magnesium, one of the essential elements in the human body, has numerous favorable effects that offer a variety of possibilities for its use in obstetric anesthesia and intensive care. Administered as a single intravenous bolus dose or a bolus followed by continuous infusion during surgery, magnesium attenuates stress response to endotracheal intubation, and reduces intraoperative anesthetic and postoperative analgesic requirements, while at the same time preserving favorable hemodynamics. Applied as part of an intrathecal or epidural anesthetic mixture, magnesium prolongs the duration of anesthesia and diminishes total postoperative analgesic consumption with no adverse maternal or neonatal effects. In obstetric intensive care, magnesium represents a first-choice medication in the treatment and prevention of eclamptic seizures. If used in recommended doses with close monitoring, magnesium is a safe and effective medication.

  18. Lloyd M. Pidgeon — Magnesium Pioneer

    NASA Astrophysics Data System (ADS)

    Brown, Robert E.

    Lloyd Montgomery Pidgeon was an unusual man in an unusual time. His contributions to the development of the magnesium industry have never been appreciated (or even known) by many of today's magnesium followers. Dr. Pidgeon, working with one technical graduate, achieved commercial development of a process to produce magnesium by reducing calcined dolomite with ferrosilicon, i.e. the silicothermic process. He also received patents for electrolytic magnesium processes. He worked with engineers to design and build six magnesium production plants in a very short period of time. The original plant at Haley, Ontario is still operating. Dr. Pidgeon received many technical honors, but was always quick-witted, with a humorous approach to life.

  19. Determination of oxygen content in magnesium and its alloys by inert gas fusion-infrared absorptiometry.

    PubMed

    Tsuge, Akira; Achiwa, Hatsumi; Morikawa, Hisashi; Uemoto, Michihisa; Kanematsu, Wataru

    2011-01-01

    A method for the determination of the oxygen content in magnesium and magnesium alloys has been developed. Inert gas fusion-infrared absorptiometry was modified by introducing a multistep heating process; a sample containing oxygen is fused with tin to form an eutectic mixture at 900°C in a graphite crucible, followed by a subsequent gradual temperature increase of up to 2000°C, which enables the evaporation of magnesium from the mixture, and subsequent solidification at the rim of the crucible. Residual tin including magnesium oxide remained at the bottom of the crucible. The oxygen in the tin is measured by a conventional inert gas fusion (IGF) method. From a comparison with the results of charged particle activation analysis, the IGF method is considered to be an attractive candidate for measuring the oxygen content in Mg and its alloys.

  20. Anhydrobiosis in yeast: influence of calcium and magnesium ions on yeast resistance to dehydration-rehydration.

    PubMed

    Trofimova, Yuliya; Walker, Graeme; Rapoport, Alexander

    2010-07-01

    The influence of calcium and magnesium ions on resistance to dehydration in the yeast, Saccharomyces cerevisiae, was investigated. Magnesium ion availability directly influenced yeast cells' resistance to dehydration and, when additionally supplemented with calcium ions, this provided further significant increase of yeast resistance to dehydration. Gradual rehydration of dry yeast cells in water vapour indicated that both magnesium and calcium may be important for the stabilization of yeast cell membranes. In particular, calcium ions were shown for the first time to increase the resistance of yeast cells to dehydration in stress-sensitive cultures from exponential growth phases. It is concluded that magnesium and calcium ion supplementations in nutrient media may increase the dehydration stress tolerance of S. cerevisiae cells significantly, and this finding is important for the production of active dry yeast preparations for food and fermentation industries.

  1. Comparison of magnesium status using X-ray dispersion analysis following magnesium oxide and magnesium citrate treatment of healthy subjects.

    PubMed

    Shechter, Michael; Saad, Tomer; Shechter, Alon; Koren-Morag, Nira; Silver, Burton B; Matetzky, Shlomi

    2012-03-01

    The magnesium content in food consumed in the Western world is steadily decreasing. Hypomagnesemia is associated with increased incidence of diabetes mellitus, metabolic syndrome, all-cause and coronary artery disease mortality. We investigated the impact of supplemental oral magnesium citrate versus magnesium oxide on intracellular magnesium levels ([Mg2+]i) and platelet function in healthy subjects with no apparent heart disease. In a randomized, prospective, double-blind, crossover study, 41 (20 women) healthy volunteers [mean age 53±8 (range 31-75) years] received either magnesium oxide monohydrate tablets (520 mg/day of elemental magnesium) or magnesium citrate tablets (295.8 mg/day of elemental magnesium) for one month (phase 1), followed by a four-week wash-out period, and then crossover treatment for one month (phase 2). [Mg2+]i was assessed from sublingual cells through x-ray dispersion (normal values 37.9±4.0 mEq/L), serum magnesium levels, platelet aggregation, and quality-of-life questionnaires were assessed before and after each phase. Oral magnesium oxide, rather than magnesium citrate, significantly increased [Mg2+]i (34.4±3 versus 36.3±2 mEq/L, p<0.001 and 34.7±2 versus 35.4±2 mEq/L, p=0.097; respectively), reduced total cholesterol (201±37 versus 186±27 mg/dL, p=0.016 and 187±28 versus 187±25 mg/dL, p=0.978; respectively) and low-density lipoprotein (LDL) cholesterol (128±22 versus 120±25 mg/dL, p=0.042 and 120±23 versus 121±22 mg/dL, p=0.622; respectively). Noteworthy is that both treatments significantly reduced epinephrine-induced platelet aggregation (78.9±16% versus 71.7±23%, p=0.013 and 81.3±15% versus 73.3±23%, p=0.036; respectively). Thus, oral magnesium oxide treatment significantly improved [Mg2+]i, total and LDL cholesterol compared with magnesium citrate, while both treatments similarly inhibited platelet aggregation in healthy subjects with no apparent heart disease.

  2. Interactions between magnesium and psychotropic drugs.

    PubMed

    Nechifor, Mihai

    2008-06-01

    Psychotropic drugs (antidepressants, antimanic drugs, antipsychotics, analgesic opioids, and others) are among the most frequently used medicines. Between these drugs and magnesium there are pharmacokinetic and pharmacodynamic interactions. Erythrocyte magnesium is decreased in patients with severe major depression (MD) vs normal subjects (44 +/- 2.7 mg/L in MD group vs 59.1 +/- 3.2 mg/L in control group, p < 0.01). Therapy with sertraline, 150 mg/day p.o. -21 days or with amitryptiline 3 x 25 mg/day p.o. 28 days increases significantly erythrocyte concentration of magnesium (56.9 +/- 5.22 mg/L after sertraline vs 44 +/- 2.7 mg/L before sertraline, p < 0.01). In patients with acute paranoid schizophrenia, erythrocyte magnesium concentration is decreased vs healthy subjects. Haloperidol, 8 mg/day, p.o. for 21 days or risperidone, 6 mg/day p.o. for 21 days have increased significantly erythrocyte magnesium concentration (46.21 +/- 3.1 mg/L before haloperidol and 54.6 +/- 2.7 mg/L after haloperidol, p < 0.05). Antimanic drugs (mood stabilizers) as carbamazepine, 600 mg/day, p.o., 4 weeks and sodium valproate, 900 mg/day p.o., 4 weeks, increased significantly magnesium in patients with bipolar disorder type I. Increased magnesium status positively correlated with enhancement of the clinical state. The existent data sustain the idea that an increase of erythrocyte magnesium is involved in the mechanism of action of some psychotropic drugs. Magnesium supply decreased the intensity of morphine-induced physical drug dependence. In heroin addicts, the plasma magnesium concentration is decreased.

  3. The influence of dietary boron supplementation on egg quality and serum calcium, inorganic phosphorus, magnesium levels and alkaline phosphatase activity in laying hens.

    PubMed

    Eren, M; Uyanik, F; Küçükersan, S

    2004-06-01

    This study was performed to investigate the influence of dietary boron (B) supplementation on egg production, interior and exterior egg quality and serum parameters related to egg formation in laying hens. Two hundred and twenty four, 18 week old, Hyline Brown 98 strain hens were assigned to 7 groups with 4 replicates. After 10 days of adaptation the hens were fed for 8 weeks on diets supplemented with 0, 5, 10, 50, 100, 200 and 400 mg/kg (diet) B (H(3)BO(3)). Live weight, feed consumption and egg production were reduced in the 400 mg/kg B supplemented group. Increases were determined in serum Ca, inorganic P and Mg levels and serum ALP activity was not influenced by supplemental B. Boron changed the interior and exterior quality of eggs. In particular, high level of B supplementation reduced live weight, feed consumption and egg production and changed some blood metabolites.

  4. Natural and synthetic modulators of SK (Kca2) potassium channels inhibit magnesium-dependent activity of the kinase-coupled cation channel TRPM7

    PubMed Central

    Chubanov, V; Mederos y Schnitzler, M; Meißner, M; Schäfer, S; Abstiens, K; Hofmann, T; Gudermann, T

    2012-01-01

    BACKGROUND AND PURPOSE Transient receptor potential cation channel subfamily M member 7 (TRPM7) is a bifunctional protein comprising a TRP ion channel segment linked to an α-type protein kinase domain. TRPM7 is essential for proliferation and cell growth. Up-regulation of TRPM7 function is involved in anoxic neuronal death, cardiac fibrosis and tumour cell proliferation. The goal of this work was to identify non-toxic inhibitors of the TRPM7 channel and to assess the effect of blocking endogenous TRPM7 currents on the phenotype of living cells. EXPERIMENTAL APPROACH We developed an aequorin bioluminescence-based assay of TRPM7 channel activity and performed a hypothesis-driven screen for inhibitors of the channel. The candidates identified were further assessed electrophysiologically and in cell biological experiments. KEY RESULTS TRPM7 currents were inhibited by modulators of small conductance Ca2+-activated K+ channels (KCa2.1–2.3; SK) channels, including the antimalarial plant alkaloid quinine, CyPPA, dequalinium, NS8593, SKA31 and UCL 1684. The most potent compound NS8593 (IC50 1.6 µM) specifically targeted TRPM7 as compared with other TRP channels, interfered with Mg2+-dependent regulation of TRPM7 channel and inhibited the motility of cultured cells. NS8593 exhibited full and reversible block of native TRPM7-like currents in HEK 293 cells, freshly isolated smooth muscle cells, primary podocytes and ventricular myocytes. CONCLUSIONS AND IMPLICATIONS This study reveals a tight overlap in the pharmacological profiles of TRPM7 and KCa2.1–2.3 channels. NS8593 acts as a negative gating modulator of TRPM7 and is well-suited to study functional features and cellular roles of endogenous TRPM7. PMID:22242975

  5. Tape casting of magnesium oxide.

    SciTech Connect

    Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

    2008-02-01

    A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

  6. Identifying acid salts of magnesium

    SciTech Connect

    Plumb, R.; Thivierge, R.F. Jr.; Xu, W.W.

    1987-11-05

    In preliminary work they found that significant quantities of certain nitrogen oxides and of sulfuric acid were absorbed by lower hydrates of magnesium sulfate. It appeared that acid salts were being formed but the known chemistry of group IIA (group 2) sulfates and acid sulfates which was worked out many years ago did not provide an explanation of their observations. They developed a new technique for delineating the solidus boundary of ternary mixtures using friability tests and applied it to the systems of interest. Magnesium acid salt hydrates with compositions on the solidus boundary could be readily identified. X-ray powder patterns confirmed the existence of two previously unknown ternary compounds, Mg/sub 2/(HSO/sub 4/)/sub 2/SO/sub 4/ x 4H/sub 2/O and Mg(HSO/sub 4/)/sub 2/ x H/sub 2/SO/sub 4/ x 3H/sub 2/O. Mixed acid sulfate-nitrate-hydrates could be detected but fuming at room temperatures interfered with quantitative determinations of the solidus boundary and X-ray measurements.

  7. Analysis Methods of Magnesium Chips

    NASA Astrophysics Data System (ADS)

    Ohmann, Sven; Ditze, André; Scharf, Christiane

    2015-11-01

    The quality of recycled magnesium from chips depends strongly on their exposure to inorganic and organic impurities that are added during the production processes. Different kinds of magnesium chips from these processes were analyzed by several methods. In addition, the accuracy and effectiveness of the methods are discussed. The results show that the chips belong either to the AZ91, AZ31, AM50/60, or AJ62 alloy. Some kinds of chips show deviations from the above-mentioned normations. Different impurities result mainly from transition metals and lime. The water and oil content does not exceed 25%, and the chip size is not more than 4 mm in the diameter. The sieve analysis shows good results for oily and wet chips. The determination of oil and water shows better results for the application of a Soxhlet compared with the addition of lime and vacuum distillation. The most accurate values for the determination of water and oil are obtained by drying at 110°C (for water) and washing with acetone (for oil) by hand.

  8. Magnesium intake, bone mineral density, and fractures: results from the Women's Health Initiative Observational Study1234

    PubMed Central

    Orchard, Tonya S; Larson, Joseph C; Alghothani, Nora; Bout-Tabaku, Sharon; Cauley, Jane A; Chen, Zhao; LaCroix, Andrea Z; Wactawski-Wende, Jean; Jackson, Rebecca D

    2014-01-01

    Background: Magnesium is a necessary component of bone, but its relation to osteoporotic fractures is unclear. Objective: We examined magnesium intake as a risk factor for osteoporotic fractures and altered bone mineral density (BMD). Design: This prospective cohort study included 73,684 postmenopausal women enrolled in the Women's Health Initiative Observational Study. Total daily magnesium intake was estimated from baseline food-frequency questionnaires plus supplements. Hip fractures were confirmed by a medical record review; other fractures were identified by self-report. A baseline BMD analysis was performed in 4778 participants. Results: Baseline hip BMD was 3% higher (P < 0.001), and whole-body BMD was 2% higher (P < 0.001), in women who consumed >422.5 compared with <206.5 mg Mg/d. However, the incidence and RR of hip and total fractures did not differ across quintiles of magnesium. In contrast, risk of lower-arm or wrist fractures increased with higher magnesium intake [multivariate-adjusted HRs of 1.15 (95% CI: 1.01, 1.32) and 1.23 (95% CI: 1.07, 1.42) for quintiles 4 and 5, respectively, compared with quintile 1; P-trend = 0.002]. In addition, women with the highest magnesium intakes were more physically active and at increased risk of falls [HR for quintile 4: 1.11 (95% CI: 1.06, 1.16); HR for quintile 5: 1.15 (95% CI: 1.10, 1.20); P-trend < 0.001]. Conclusions: Lower magnesium intake is associated with lower BMD of the hip and whole body, but this result does not translate into increased risk of fractures. A magnesium consumption slightly greater than the Recommended Dietary Allowance is associated with increased lower-arm and wrist fractures that are possibly related to more physical activity and falls. This trial was registered at clinicaltrials.gov as NCT00000611. PMID:24500155

  9. Biofunctional composite coating architectures based on polycaprolactone and nanohydroxyapatite for controlled corrosion activity and enhanced biocompatibility of magnesium AZ31 alloy.

    PubMed

    Zomorodian, A; Garcia, M P; Moura E Silva, T; Fernandes, J C S; Fernandes, M H; Montemor, M F

    2015-03-01

    In this work a biofunctional composite coating architecture for controlled corrosion activity and enhanced cellular adhesion of AZ31 Mg alloys is proposed. The composite coating consists of a polycaprolactone (PCL) matrix modified with nanohydroxyapatite (HA) applied over a nanometric layer of polyetherimide (PEI). The protective properties of the coating were studied by electrochemical impedance spectroscopy (EIS), a non-disturbing technique, and the coating morphology was investigated by field emission scanning electron microscopy (FE-SEM). The results show that the composite coating protects the AZ31 substrate. The barrier properties of the coating can be optimized by changing the PCL concentration. The presence of nanohydroxyapatite particles influences the coating morphology and decreases the corrosion resistance. The biocompatibility was assessed by studying the response of osteoblastic cells on coated samples through resazurin assay, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The results show that the polycaprolactone to hydroxyapatite ratio affects the cell behavior and that the presence of hydroxyapatite induces high osteoblastic differentiation. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Conserved Chloroplast Open-reading Frame ycf54 Is Required for Activity of the Magnesium Protoporphyrin Monomethylester Oxidative Cyclase in Synechocystis PCC 6803

    PubMed Central

    Hollingshead, Sarah; Kopečná, Jana; Jackson, Philip J.; Canniffe, Daniel P.; Davison, Paul A.; Dickman, Mark J.; Sobotka, Roman; Hunter, C. Neil

    2012-01-01

    The cyclase step in chlorophyll (Chl) biosynthesis has not been characterized biochemically, although there are some plausible candidates for cyclase subunits. Two of these, Sll1214 and Sll1874 from the cyanobacterium Synechocystis 6803, were FLAG-tagged in vivo and used as bait in separate pulldown experiments. Mass spectrometry identified Ycf54 as an interaction partner in each case, and this interaction was confirmed by a reciprocal pulldown using FLAG-tagged Ycf54 as bait. Inactivation of the ycf54 gene (slr1780) in Synechocystis 6803 resulted in a strain that exhibited significantly reduced Chl levels. A detailed analysis of Chl precursors in the ycf54 mutant revealed accumulation of very high levels of Mg-protoporphyrin IX methyl ester and only traces of protochlorophyllide, the product of the cyclase, were detected. Western blotting demonstrated that levels of the cyclase component Sll1214 and the Chl biosynthesis enzymes Mg-protoporphyrin IX methyltransferase and protochlorophyllide reductase are significantly impaired in the ycf54 mutant. Ycf54 is, therefore, essential for the activity and stability of the oxidative cyclase. We discuss a possible role of Ycf54 as an auxiliary factor essential for the assembly of a cyclase complex or even a large multienzyme catalytic center. PMID:22711541

  11. Magnesium status and the effect of magnesium supplementation in feline hypertrophic cardiomyopathy.

    PubMed Central

    Freeman, L M; Brown, D J; Smith, F W; Rush, J E

    1997-01-01

    Magnesium deficiency has been associated with the development of cardiovascular disease in several species. Cats may be predisposed to alterations in magnesium status because of recent changes in the composition of commercial feline diets. The purposes of this study were 1) to examine the dietary history of cats with hypertrophic cardiomyopathy (HCM), 2) to study magnesium status of cats with HCM compared to normal cats, and 3) to determine the effects of magnesium supplementation in cats with HCM. In part 1 of the study, diets of 65 cats with HCM were examined retrospectively. Forty of the 45 cats for which diets could be determined (89%) ate a diet designed to be magnesium-restricted and/or to produce an acidic urine. In part 2 of the study, 10 cats with HCM were compared to 10 healthy control cats for serum creatinine and magnesium; urine creatinine and magnesium, urine specific gravity and pH, and fractional excretion of magnesium. Urine creatinine and specific gravity were higher in control cats than in cats with HCM. No other differences were found between the 2 groups. In part 3, cats with HCM were supplemented with either 210 mg magnesium chloride (n = 15) or 210 mg lactose (n = 15) for 12 wk. No differences between the 2 groups were found for changes in either magnesium status or echocardiographic parameters. However, the 30 cats with HCM, as a group, did show significant improvements in measures of cardiac hypertrophy over the 12-week period. This was likely the result of treatment with other medications, rather than the magnesium supplementation. The results of this study suggest that cats with HCM are likely to be fed magnesium-restricted diets, but that they do not appear to have altered magnesium status compared to healthy controls. PMID:9243004

  12. Proposed formation mechanism and active species of hydrogen molecules generated from a novel magnesium-citric acid-hydroxypropyl cellulose coating (MgCC) material

    NASA Astrophysics Data System (ADS)

    Kobayashi, Shigeki; Chikuma, Toshiyuki; Chiba, Kazuyoshi; Tsuchiya, Daisuke; Hirai, Tomomitsu

    2016-02-01

    The presence of acids is known to accelerate the reaction (Mg + 2H2O = Mg(OH)2 + H2). We developed a novel Mg-citric acid coating (MgCC) material produced by milling Mg powder coated with hydroxypropyl cellulose (HPC); because of its H2 generation, this material could be used in antioxidant therapy and antiaging applications. After milling in the presence of citric acid, this material produced H2-rich water upon addition to cooled water. Although the reaction was considered to involve a two-electron transfer from Mg to 2H2O, the role of the acid in H2 generation remains incompletely understood. To clarify the reaction mechanism, we performed studies on the deuterium kinetic isotope effects (KIE) and electron spin resonance (ESR). We observed differences in the concentration ratios, such as H2/D2 > 1 and H2/(H2 + D2 + HD) > 1, involved in H2, D2, and (H2 + D2 + HD) production, and found that adducts with hydrogen atoms (Hrad) were not obtained from the spin-trapping reaction between 5-(2, 2-Dimethyl-1,3-propoxy cyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO) and the MgCC material. The H2, D2, and HD produced from MgCC were identified by using a gas chromatograph connected to a mass spectrometer. The spin-trapping techniques showed that the Hrad adducts formed by the reaction of NaBH4 with CYPMPO could not be observed from reaction of MGCC with CYPMPO in H2O. The data suggest that the rate-controlling step and proposed transition state (TS) exist in the reaction pathway of the O-H bond cleavage and H-H bond formation. A TS of a structure such as [Mg(OH2)2]∗ could be expected in the reaction pathway between Mg and 2H2O by density functional theory calculations. Also, these results show that H2 generation is accelerated in the presence of acids because the activation energy of the TS is significantly smaller than that of H2O.

  13. [Diagnosis of magnesium deficiency in intensive care patients].

    PubMed

    Saur, P M; Zielmann, S; Roth, A T; Frank, L; Warneke, G; Radke, A; Ensink, F B; Kettler, D

    1996-02-01

    Magnesium deficiency was investigated in critically ill patients, comparing measurements of plasma concentrations with the results obtained by the magnesium tolerance test. 20 critically ill patients (5 females, 15 males) between the ages of 27 and 86 were investigated. Magnesium plasma concentrations were determined before the magnesium tolerance test according to Ryzen was performed. For this purpose, magnesium sulfate (0.1 mmol/kg) was infused intravenously over four hours. Renal magnesium excretion was measured in the 24 h urine beginning at the start of the infusion. Magnesium concentrations in plasma and urine were determined using atomic absorption spectrophotometry. In 12 patients magnesium plasma concentrations were decreased to 0.58-0.79 mmol/l. 6 patients showed values within the normal range of 0.80 to 1.0 mmol/l. In 2 patients the plasma concentration was increased to 1.07 and 1.27 mmol/l. Parenteral magnesium tolerance testing revealed a considerable magnesium deficiency by retention of 65-100% of the loading dose in 14 of the 20 patients. The remaining 6 patients retained 23-48% of the loading dose, thus demonstrating a moderate magnesium deficiency. Determination of magnesium plasma concentration appears suitable as an informative preliminary survey, since low values are reliable indicating a magnesium deficiency. However, this study confirms that normal magnesium plasma concentrations do not exclude a considerable magnesium deficiency, which is more sensitively determined by the magnesium tolerance test.

  14. Cobalt-Magnesium and Iron-Magnesium Complexes with Weakened Dinitrogen Bridges

    PubMed Central

    Dugan, Thomas R.; MacLeod, K. Cory; Brennessel, William W.

    2013-01-01

    The cooperative binding of N2 by late transition metals and main-group metals is a promising strategy for N-N bond weakening and activation. We report the use of activated Rieke magnesium for reduction of iron and cobalt complexes supported by bulky β-diketiminate ligands. Binding of N2 is accompanied by assembly of a linear M-NN-Mg-NN-M (M = Co, Fe) core with N-N bonds that are weakened, as judged by infrared spectroscopy. Both the cobalt and iron complexes require THF solvent, because of Mg-THF binding. The cobalt complex can be isolated as a pure solid, but the iron complex is stable only in solution. These results demonstrate the correlation between the binding mode and N-N weakening in heterobimetallic N2 complexes. PMID:24367236

  15. The unexpected discovery of the Mg(HMDS) 2 /MgCl 2 complex as a magnesium electrolyte for rechargeable magnesium batteries

    DOE PAGES

    Liao, Chen; Sa, Niya; Key, Baris; ...

    2015-02-02

    We developed a unique class of non-Grignard, aluminum-free magnesium electrolytes based on a simple mixture of magnesium compounds: magnesium hexamethyldisilazide (Mg(HMDS)2) and magnesium chloride (MgCl2).

  16. Microstructure-Property Correlation in Magnesium-based Hydrogen Storage Systems: The Case for Ball-milled Magnesium Hydride Powder and Magnesium-based Multilayered Composites

    NASA Astrophysics Data System (ADS)

    Danaie, Mohsen

    The main focus of this thesis is the characterization of defects and microstructure in high-energy ball milled magnesium hydride powder and magnesium-based multilayered composites. Enhancement in kinetics of hydrogen cycling in magnesium can be achieved by applying severe plastic deformation. A literature survey reveals that, due to extreme instability of alpha-MgH 2 in transmission electron microscope (TEM), the physical parameters that researchers have studied are limited to particle size and grain size. By utilizing a cryogenic TEM sample holder, we extended the stability time of the hydride phase during TEM characterization. Milling for only 30 minutes resulted in a significant enhancement in desorption kinetics. A subsequent annealing cycle under pressurized hydrogen reverted the kinetics to its initial sluggish state. Cryo-TEM analysis of the milled hydride revealed that mechanical milling induces deformation twinning in the hydride microstructure. Milling did not alter the thermodynamics of desorption. Twins can enhance the kinetics by acting as preferential locations for the heterogeneous nucleation of metallic magnesium. We also looked at the phase transformation characteristics of desorption in MgH2. By using energy-filtered TEM, we investigated the morphology of the phases in a partially desorbed state. Our observations prove that desorption phase transformation in MgH2 is of "nucleation and growth" type, with a substantial energy barrier for nucleation. This is contrary to the generally assumed "core-shell" structure in most of the simulation models for this system. We also tested the hydrogen storage cycling behavior of bulk centimeter-scale Mg-Ti and Mg-SS multilayer composites synthesized by accumulative roll-bonding. Addition of either phase (Ti or SS) allows the reversible hydrogen sorption at 350°C, whereas identically roll-bonded pure magnesium cannot be absorbed. In the composites the first cycle of absorption (also called "activation

  17. Chemical conversion coating for protecting magnesium alloys from corrosion

    DOEpatents

    Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh; Hornish, Peter; Jain, Mohit

    2016-01-05

    A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds as self-healing moieties to defect sites, thus providing active corrosion protection.

  18. Electrical transport behavior of nonstoichiometric magnesium-zinc ferrite

    SciTech Connect

    Ghatak, S.; Sinha, M.; Meikap, A.K.; Pradhan, S.K.

    2010-08-15

    This paper presents the direct current conductivity, alternate current conductivity and dielectric properties of nonstoichiometric magnesium-zinc ferrite below room temperature. The frequency exponent (s) of conductivity shows an anomalous temperature dependency. The magnitude of the temperature exponent (n) of dielectric permittivity strongly depends on frequency and its value decreases with increasing frequency. The grain boundary contribution is dominating over the grain contribution in conduction process and the temperature dependence of resistance due to grain and grain boundary contribution exhibits two activation regions. The ferrite shows positive alternating current magnetoconductivity. The solid state processing technique was used for the preparation of nanocrystalline ferrite powder from oxides of magnesium, zinc and iron. The X-ray diffraction methods were used in determining the structure and composition of obtained ferrite, while multimeter, impedance analyzer, liquid nitrogen cryostat and electromagnet were used in the study of conducting and dielectric properties of ferrite.

  19. Monitoring Biodegradation of Magnesium Implants with Sensors

    NASA Astrophysics Data System (ADS)

    Zhao, Daoli; Wang, Tingting; Guo, Xuefei; Kuhlmann, Julia; Doepke, Amos; Dong, Zhongyun; Shanov, Vesselin N.; Heineman, William R.

    2016-04-01

    Magnesium and its alloys exhibit properties such as high strength, light weight, and in vivo corrosion that make them promising candidates for the development of biodegradable metallic implant materials for bone repair, stents and other medical applications. Sensors have been used to monitor the corrosion of magnesium and its alloys by measuring the concentrations of the following corrosion products: magnesium ions, hydroxyl ions and hydrogen gas. The corrosion characterization system with home-made capillary pH and Mg2+ microsensors has been developed for real-time detection of magnesium corrosion in vitro. A hydrogen gas sensor was used to monitor the corrosion of magnesium by measuring the concentration of the hydrogen gas reaction product in vivo. The high permeability of hydrogen through skin allows transdermal monitoring of the biodegradation of a magnesium alloy implanted beneath the skin by detecting hydrogen gas at the skin surface. The sensor was used to map hydrogen concentration in the vicinity of an implanted magnesium alloy.

  20. Magnesium based degradable biomaterials: A review

    NASA Astrophysics Data System (ADS)

    Gu, Xue-Nan; Li, Shuang-Shuang; Li, Xiao-Ming; Fan, Yu-Bo

    2014-09-01

    Magnesium has been suggested as a revolutionary biodegradable metal for biomedical applications. The corrosion of magnesium, however, is too rapid to match the rates of tissue healing and, additionally, exhibits the localized corrosion mechanism. Thus it is necessary to control the corrosion behaviors of magnesium for their practical use. This paper comprehensively reviews the research progress on the development of representative magnesium based alloys, including Mg-Ca, Mg-Sr, Mg-Zn and Mg-REE alloy systems as well as the bulk metallic glass. The influence of alloying element on their microstructures, mechanical properties and corrosion behaviors is summarized. The mechanical and corrosion properties of wrought magnesium alloys are also discussed in comparison with those of cast alloys. Furthermore, this review also covers research carried out in the field of the degradable coatings on magnesium alloys for biomedical applications. Calcium phosphate and biodegradable polymer coatings are discussed based on different preparation techniques used. We also compare the effect of different coatings on the corrosion behaviors of magnesium alloys substrate.

  1. Magnesium in cardioplegia: Is it necessary?

    PubMed Central

    Shakerinia, Tooraj; Ali, Idris M.; Sullivan, John A.P.

    1996-01-01

    Objective To study the effectiveness of magnesium in cardioplegic solution in preventing postoperative arrhythmias and perioperative ischemia. Design Randomized, control study. Setting The cardiovascular surgery division of a major referral centre for the maritime provinces of Canada. Patients Fifty patients scheduled to undergo coronary artery bypass who had a normal ejection fraction, normal preoperative serum magnesium level and no history of atrial or ventricular arrhythmia were randomized into two groups of 25 patients. One group received magnesium sulfate (15 mmol/L) in the cardioplegic solution (group 1), the other (control) group did not receive magnesium sulfate in the cardioplegic solution (group 2). Intervention Coronary artery bypass grafting during which myocardial protection was provided by intermittent cold blood cardioplegia. Outcome Measures Postoperative serum magnesium levels, cardiac-related death, infarction and arrhythmias. Results All group 2 patients had a lower postoperative serum magnesium level than group 1 patients. There were no cardiac-related deaths in either group. More group 2 patients had ischemic electrocardiographic changes than group 1 patients (p < 0.03). Non-Q-wave myocardial infarction occurred in two patients (one in each group). Eight patients in group 2 had atrial fibrillation compared with five patients in group 1. Ventricular ectopia occurred significantly (p < 0.01) more frequently in group 2 than in group 1. Conclusion The addition of magnesium to the cardioplegic solution is beneficial in reducing the incidence of perioperative ischemia and ventricular arrhythmia in patients who undergo coronary bypass grafting. PMID:8857989

  2. Magnesium-dependent processes are targets of bacterial manganese toxicity

    PubMed Central

    Hohle, Thomas H.; O’Brian, Mark R.

    2014-01-01

    A Bradyrhizobium japonicum mutant defective in the gene encoding the high affinity Mn2+ transporter MntH has a severe growth phenotype under manganese limitation. Here, we isolated suppressor mutants of an mntH strain that grew under manganese limitation, and activities of high affinity Mn2+ transport and Mn2+-dependent enzymes were partially rescued. The suppressor strains harbor gain-of-function mutations in the gene encoding the Mg2+ channel MgtE. The MgtE variants likely allow Mn2+ entry via loss of a gating mechanism that normally holds the transporter in the closed state when cellular Mg2+ levels are high. Both MgtE-dependent and -independent suppressor phenotypes were recapitulated by magnesium-limited growth of the mntH strain. Growth studies of wild type cells suggest that manganese is toxic to cells when environmental magnesium is low. Moreover, extracellular manganese and magnesium levels were manipulated to inhibit growth without substantially altering the intracellular content of either metal, implying that manganese toxicity depends on its cellular distribution rather than the absolute concentration. Mg2+-dependent enzyme activities were found to be inhibited or stimulated by Mn2+. We conclude that Mn2+ can occupy Mg2+-binding sites in cells, and suggest that Mg2+-dependent processes are targets of manganese toxicity. PMID:24975873

  3. Magnesium-dependent processes are targets of bacterial manganese toxicity.

    PubMed

    Hohle, Thomas H; O'Brian, Mark R

    2014-08-01

    A Bradyrhizobium japonicum mutant defective in the gene encoding the high-affinity Mn(2+) transporter MntH has a severe growth phenotype under manganese limitation. Here, we isolated suppressor mutants of an mntH strain that grew under manganese limitation, and activities of high-affinity Mn(2+) transport and Mn(2+) -dependent enzymes were partially rescued. The suppressor strains harbour gain-of-function mutations in the gene encoding the Mg(2+) channel MgtE. The MgtE variants likely allow Mn(2+) entry via loss of a gating mechanism that normally holds the transporter in the closed state when cellular Mg(2+) levels are high. Both MgtE-dependent and MgtE-independent suppressor phenotypes were recapitulated by magnesium-limited growth of the mntH strain. Growth studies of wild-type cells suggest that manganese is toxic to cells when environmental magnesium is low. Moreover, extracellular manganese and magnesium levels were manipulated to inhibit growth without substantially altering the intracellular content of either metal, implying that manganese toxicity depends on its cellular distribution rather than the absolute concentration. Mg(2+) -dependent enzyme activities were found to be inhibited or stimulated by Mn(2+) . We conclude that Mn(2+) can occupy Mg(2+) binding sites in cells, and suggest that Mg(2+) -dependent processes are targets of manganese toxicity.

  4. Room temperature magnesium electrorefining by using non-aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Dilasari, Bonita; Ku, Heesuk; Kim, Hansu; Kwon, Kyungjung; Lee, Churl Kyoung

    2016-09-01

    The increasing usage of magnesium inevitably leads to a fast increase in magnesium scrap, and magnesium recycling appears extremely beneficial for cost reduction, preservation of natural resources and protection of the environment. Magnesium refining for the recovery of high purity magnesium from metal scrap alloy (AZ31B composed of magnesium, aluminum, zinc, manganese and copper) at room temperature is investigated with a non-aqueous electrolyte (tetrahydrofuran with ethyl magnesium bromide). A high purity (99.999%) of electrorefined magneisum with a smooth and dense surface is obtained after potentiostatic electrolysis with an applied voltage of 2 V. The selective dissolution of magnesium from magnesium alloy is possible by applying an adequate potential considering the tolerable impurity level in electrorefined magnesium and processing time. The purity estimation method suggested in this study can be useful in evaluating the maximum content of impurity elements.

  5. Nonaqueous magnesium electrochemistry and its application in secondary batteries.

    PubMed

    Aurbach, Doron; Weissman, Idit; Gofer, Yosef; Levi, Elena

    2003-01-01

    A revolution in modern electronics has led to the miniaturization and evolution of many portable devices, such as cellular telephones and laptop computers, since the 1980s. This has led to an increasing demand for new and compatible energy storage technologies. Furthermore, a growing awareness of pollution issues has provided a strong impetus for the science and technology community to develop alternatives with ever-higher energy densities, with the ultimate goal of being able to propel electric vehicles. Magnesium's thermodynamic properties make this metal a natural candidate for utilization as an anode in high-energy-density, rechargeable battery systems. We report herein on the results of extensive studies on magnesium anodes and magnesium insertion electrodes in nonaqueous electrolyte solutions. Novel, rechargeable nonaqueous magnesium battery systems were developed based on the research. This work had two major challenges: one was to develop electrolyte solutions with especially high anodic stability in which magnesium anodes can function at a high level of cycling efficiency; the other was to develop a cathode that can reversibly intercalate Mg ions in these electrolyte systems. The new magnesium batteries consist of Mg metal anodes, an electrolyte with a general structure of Mg(AlX(3-n)R(n)R')(2) (R',R = alkyl groups, X = halide) in ethereal solutions (e.g., tetrahydrofuran, polyethers of the "glyme" family), and Chevrel phases of MgMo(3)S(4) stoichiometry as highly reversible cathodes. With their practical energy density expected to be >60 Wh/Kg, the battery systems can be cycled thousands of times with almost no capacity fading. The batteries are an environmentally friendly alternative to lead-acid and nickel-cadmium batteries and are composed of abundant, inexpensive, and nonpoisonous materials. The batteries are expected to provide superior results in large devices that require high-energy density, high cycle life, a high degree of safety, and low

  6. Thermal analysis of magnesium reactions with nitrogen/oxygen gas mixtures.

    PubMed

    Chunmiao, Yuan; Lifu, Yu; Chang, Li; Gang, Li; Shengjun, Zhong

    2013-09-15

    The thermal behavior and kinetic parameters of magnesium powder subjected to a nitrogen-rich atmosphere was investigated in thermogravimetric (TG) and differential scanning calorimeter (DSC) experiments with oxygen/nitrogen mixtures heated at rates of 5, 10, 15, and 20 °C/min. At higher temperature increase rates, the observed oxidation or nitridation steps shifted toward higher temperatures. The comparison of mass gain and heat of reaction in different nitrogen concentrations is helpful in interpreting the inerting effect of nitrogen on magnesium powder explosion in closed vessels. Activation energies for oxidation in air calculated by the Kissinger-Akahira-Sunose (KAS) method are generally consistent with previously published reports, but the method was not successful for the entire nitridation process. The change of activation energy with temperature was related to protective properties of the corresponding coating layer at particle surfaces. Two main coating layer growth processes were found in magnesium oxidation and nitridation using a modified Dreizin method which was also employed to determine activation energy for both magnesium oxidation and nitridation. For magnesium powder oxidation, activation energy calculated by the Dreizin method was close to that by KAS. Variation in activation energies was a function of different mechanisms inherent in the two methods.

  7. Improving halide-containing magnesium-ion electrolyte performance via sterically hindered alkoxide ligands

    NASA Astrophysics Data System (ADS)

    Nist-Lund, Carl A.; Herb, Jake T.; Arnold, Craig B.

    2017-09-01

    While homoleptic magnesium dialkoxides (MgR2, R = alkoxide) have shown promise as precursors for magnesium-ion electrolytes, the effect of ligand steric bulk on the performance of electrolytes based on these compounds is not fully understood. Increasing steric hindrance, studied via R groups with additional phenyl moieties, produces electrolytes with sequentially lower deposition overpotentials (less than -90 mV), higher purity Mg deposits (ca. 100% Mg), and lower overall cell impedances. The two largest alkoxide ligands show consistent cycling behavior and low stripping and plating overpotentials over 200 constant-current plating/stripping cycles. A deep-red visual change and the presence of large solubilized magnesium particulates above 450 nm in size is observed in an electrolyte containing magnesium bis(triphenylmethoxide) and aluminum chloride in contact with an abraded magnesium anode. Further morphological and impedance characterization show that this electrolyte system rapidly activates the magnesium metal anode surface to produce low overpotentials and, as such, is a candidate for further investigation.

  8. Direct writing of polymeric coatings on magnesium alloy for tracheal stent applications.

    PubMed

    Perkins, Jessica; Xu, Zhigang; Smith, Christopher; Roy, Abhijit; Kumta, Prashant N; Waterman, Jenora; Conklin, Dawn; Desai, Salil

    2015-05-01

    This paper investigates the direct-write inkjet method for depositing multi-layer coatings of biodegradable polymers on magnesium alloy surface. Immersion studies were conducted on Poly(lactic-co-glycolic) acid (PLGA), polycaprolactone (PCL), and poly-ester urethane urea (PEUU) coatings to determine the corrosion behavior of different samples based on their varying degradation properties. Using the inductively coupled plasma spectroscopy, a reduction in magnesium ion concentration was observed from the polymer-coated samples indicative of the lower corrosion rates as compared to the uncoated Mg substrate. Findings also showed correlation between the release of the magnesium ions and the health of fully differentiated normal human bronchial epithelial (NHBE) cells via evaluation of key biomarkers of inflammation and toxicity, cyclooxygenase-2 (COX-2) and lactate dehydrogenase (LDH), respectively. The induction of COX-2 gene expression was proportional to the increase in magnesium exposure. In addition, the release of higher magnesium content from uncoated and PCL polymer coated samples resulted in lower LDH activity based on the favorable response of the NHBE cells. PEUU and PLGA polymer coatings provided good barrier layer corrosion protection. This research evaluates candidate polymer coatings as a source for therapeutic agents and barrier layer to control the corrosion of magnesium alloys for tracheal applications.

  9. Factors Underlying Bursting Behavior in a Network of Cultured Hippocampal Neurons Exposed to Zero Magnesium

    PubMed Central

    Mangan, Patrick S.; Kapur, Jaideep

    2010-01-01

    Factors contributing to reduced magnesium-induced neuronal action potential bursting were investigated in primary hippocampal cell culture at high and low culture density. In nominally zero external magnesium medium, pyramidal neurons from high-density cultures produced recurrent spontaneous action potential bursts superimposed on prolonged depolarizations. These bursts were partially attenuated by the NMDA receptor antagonist D-APV. Pharmacological analysis of miniature excitatory postsynaptic currents (EPSCs) revealed 2 components: one sensitive to D-APV and another to the AMPA receptor antagonist DNQX. The components were kinetically distinct. Participation of NMDA receptors in reduced magnesium-induced synaptic events was supported by the localization of the NR1 subunit of the NMDA receptor with the presynaptic vesicular protein synaptophysin. Presynaptically, zero magnesium induced a significant increase in EPSC frequency likely attributable to increased neuronal hyperexcitability induced by reduced membrane surface charge screening. Mean quantal content was significantly increased in zero magnesium. Cells from low-density cultures did not exhibit action potential bursting in zero magnesium but did show increased EPSC frequency. Low-density neurons had less synaptophysin immunofluorescence and fewer active synapses as determined by FM1-43 analysis. These results demonstrate that multiple factors are involved in network bursting. Increased probability of transmitter release presynaptically, enhanced NMDA receptor-mediated excitability postsynaptically, and extent of neuronal interconnectivity contribute to initiation and maintenance of elevated network excitability. PMID:14534286

  10. Magnesium in North America: A Changing Landscape

    NASA Astrophysics Data System (ADS)

    Slade, Susan

    The changing landscape of North American manufacturing in the context of global competition is impacting the market of all raw materials, including magnesium. Current automotive fuel economy legislation and pending legislation on the emissions of greenhouse gases are impacting magnesium's largest consuming industries, such as aluminum, automotive components, steel and transition metals. These industries are all considering innovative ways to efficiently incorporate the needed raw materials into their processes. The North American magnesium market differs from other regions based on maturity, supply streams, changing manufacturing capabilities and trade cases, combined with the transformation of North American manufacturing.

  11. Magnesium doping of boron nitride nanotubes

    DOEpatents

    Legg, Robert; Jordan, Kevin

    2015-06-16

    A method to fabricate boron nitride nanotubes incorporating magnesium diboride in their structure. In a first embodiment, magnesium wire is introduced into a reaction feed bundle during a BNNT fabrication process. In a second embodiment, magnesium in powder form is mixed into a nitrogen gas flow during the BNNT fabrication process. MgB.sub.2 yarn may be used for superconducting applications and, in that capacity, has considerably less susceptibility to stress and has considerably better thermal conductivity than these conventional materials when compared to both conventional low and high temperature superconducting materials.

  12. Boron Clusters as Highly Stable Magnesium-Battery Electrolytes**

    PubMed Central

    Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W

    2014-01-01

    Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electrolytes is very high. PMID:24519845

  13. Magnesium stearine production via direct reaction of palm stearine and magnesium hydroxide

    NASA Astrophysics Data System (ADS)

    Pratiwi, M.; Ylitervo, P.; Pettersson, A.; Prakoso, T.; Soerawidjaja, T. H.

    2017-06-01

    The fossil oil production could not compensate with the increase of its consumption, because of this reason the renewable alternative energy source is needed to meet this requirement of this fuel. One of the methods to produce hydrocarbon is by decarboxylation of fatty acids. Vegetable oil and fats are the greatest source of fatty acids, so these can be used as raw material for biohydrocarbon production. From other researchers on their past researchs, by heating base soap from divalent metal, those metal salts will decarboxylate and produce hydrocarbon. This study investigate the process and characterization of magnesium soaps from palm stearine by Blachford method. The metal soaps are synthesized by direct reaction of palm stearine and magnesium hydroxide to produce magnesium stearine and magnesium stearine base soaps at 140-180°C and 6-10 bar for 3-6 hours. The operation process which succeed to gain metal soaps is 180°C, 10 bar, for 3-6 hours. These metal soaps are then compared with commercial magnesium stearate. Based on Thermogravimetry Analysis (TGA) results, the decomposition temperature of all the metal soaps were 250°C. Scanning Electron Microscope with Energy Dispersive X-ray (SEM-EDX) analysis have shown the traces of sodium sulphate for magnesium stearate commercial and magnesium hydroxide for both type of magnesium stearine soaps. The analysis results from Microwave Plasma-Atomic Emission Spectrometry (MP-AES) have shown that the magnesium content of magnesium stearine approximate with magnesium stearate commercial and lower compare with magnesium stearine base soaps. These experiments suggest that the presented saponification process method could produced metal soaps comparable with the commercial metal soaps.

  14. Development and validation of simple titrimetric method for the determination of magnesium content in esomeprazole magnesium.

    PubMed

    Haddadin, R N; Issa, A Y

    2011-07-01

    A simple and inexpensive titrimetric method for the determination of magnesium ion in esomeprazole magnesium raw material was developed and validated according to International Conference on Harmonization guidelines and the United States Pharmacopoeia. The method depends on complex formation between EDTA and magnesium ion. The method was proven to be valid, equivalent and useful as an alternative method to the current pharmacopeial methods that are based on atomic absorption spectrometry.

  15. Development and Validation of Simple Titrimetric Method for the Determination of Magnesium Content in Esomeprazole Magnesium

    PubMed Central

    Haddadin, R. N.; Issa, A. Y.

    2011-01-01

    A simple and inexpensive titrimetric method for the determination of magnesium ion in esomeprazole magnesium raw material was developed and validated according to International Conference on Harmonization guidelines and the United States Pharmacopoeia. The method depends on complex formation between EDTA and magnesium ion. The method was proven to be valid, equivalent and useful as an alternative method to the current pharmacopeial methods that are based on atomic absorption spectrometry. PMID:22707837

  16. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap through Combined Refining and Solid Oxide Membrane Electrolysis Processes

    SciTech Connect

    Xiaofei Guan; Peter A. Zink; Uday B. Pal; Adam C. Powell

    2012-01-01

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.% Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the magnesium content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapor. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium.

  17. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap through Combined Refining and Solid Oxide Membrane (SOM) Electrolysis Processes

    NASA Astrophysics Data System (ADS)

    Guan, Xiaofei; Zink, Peter; Pal, Uday

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5 wt.%Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the Mg content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapors in a separate condenser. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium; could not collect and weigh all of the magnesium recovered.

  18. Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap Through Combined Refining and Solid Oxide Membrane (SOM) Electrolysis Processes

    SciTech Connect

    Guan, Xiaofei; Zink, Peter; Pal, Uday

    2012-03-11

    Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.%Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the Mg content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapors in a separate condenser. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium; could not collect and weigh all of the magnesium recovered.

  19. Magnesium levels in critically ill patients. What should we measure?

    PubMed

    Huijgen, H J; Soesan, M; Sanders, R; Mairuhu, W M; Kesecioglu, J; Sanders, G T

    2000-11-01

    We studied the relation between ionized magnesium, total magnesium, and albumin levels in serum of 115 critically ill patients and the role of extracellular and intracellular magnesium in outcome prediction. Levels of serum total and ionized magnesium, serum albumin, and magnesium in mononuclear blood cells and erythrocytes were measured and the APACHE II score and 1-month mortality recorded. Of all patients, 51.3% had a serum total magnesium concentration below the reference range. In 71% of these hypomagnesemic patients, a normal serum ionized magnesium concentration was measured. None of the patients had an intracellular magnesium concentration below the reference limit. Except for serum total and ionized magnesium, none of the magnesium parameters correlated significantly with each other. A significantly negative correlation was found between serum albumin and the fraction ionized magnesium. There was no association between low extracellular or intracellular magnesium and clinical outcome. The observation of hypomagnesemia in critically ill patients depends on which magnesium fraction is measured. The lack of correlation with clinical outcome suggests hypomagnesemia to be merely an epiphenomenon. Reliable concentrations of serum ionized magnesium can be obtained only by direct measurement and not by calculation from serum total magnesium and albumin.

  20. Struvite precipitation and phosphorus removal using magnesium sacrificial anode.

    PubMed

    Kruk, Damian J; Elektorowicz, Maria; Oleszkiewicz, Jan A

    2014-04-01

    Struvite precipitation using magnesium sacrificial anode as the only source of magnesium is presented. High-purity magnesium alloy cast anode was found to be very effective in recovery of high-quality struvite from water solutions and from supernatant of fermented waste activated sludge from a wastewater treatment plant that does not practice enhanced biological phosphorus removal. Struvite purity was strongly dependent on the pH and the electric current density. Optimum pH of the 24 mM phosphorus and 46 mM ammonia solution (1:1.9 P:N ratio) was in the broad range between 7.5 and 9.3, with struvite purity exceeding 90%. Increasing the current density resulted in elevated struvite purity. No upper limits were observed in the studied current range of 0.05-0.2 A. Phosphorus removal rate was proportional to the current density and comparable for tests with water solutions and with the supernatant from fermented sludge. The highest P-removal rate achieved was 4.0 mg PO4-P cm(-2) h(-1) at electric current density of 45 A m(-2). Initial substrate concentrations affected the rate of phosphorus removal. The precipitated struvite accumulated in bulk liquid with significant portions attached to the anode surface from which regular detachment occurred. Copyright © 2013 Elsevier Ltd. All rights reserved.