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Results for “Magnesium Compounds”

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PubMed2004

Discovery of ancient silicate stardust in a meteorite.

We have discovered nine presolar silicate grains from the carbonaceous chondrite Acfer 094. Their anomalous oxygen isotopic compositions indicate formation in the atmospheres of evolved stars. Two grains are identified as pyroxene, two as olivine, one as a glass with embedded metal and sulfides (GEMS), and one as an Al-rich silicate. One grain is enriched in 26Mg, which is attributed to the radioactive decay of 26Al and provides information about mixing processes in the parent star. This discovery opens new means for studying stellar processes and conditions in various solar system environments.

Aluminum↗
PubMed2005

Supernova olivine from cometary dust.

An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

Cosmic Dust↗
PubMed1997

Some silicates.

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Animals↗
PubMed1985

Ultrastructural study of mineral fiber uptake by hepatocytes in vitro.

Cellular interactions of a series of fibrous materials were examined by the use of a well established in vitro system. Primary cultures of hepatocytes were exposed to natural attapulgite, synthetic xonotlite and natural sepiolite. Ultrastructural analyses revealed that hepatocytes can engage in the phagocytosis of all 3 types of fibers over an exposure period of 20 h. Attapulgite fibers were found in plasma membrane invaginations, and deeper in the cytoplasm, in vesicles exhibiting various shapes. Xonotlite was also incorporated in plasma membrane invaginations; furthermore, these fibers were present in large vacuoles where they were circumscribed by membranes and appeared somewhat isolated from the cytoplasm. Sepiolite fibers were also taken up by the cells and could likewise be identified in the previously described structures. These observations point to the relevance of the hepatocyte model for investigating the effects of fibrous materials at the cellular level.

Animals↗
PubMed2000

Gel-derived materials of a CaO-P(2)O(5)-SiO(2) system modified by boron, sodium, magnesium, aluminum, and fluorine compounds.

Bioactive glass-ceramic materials of the CaO-P(2)O(5)-SiO(2) system modified by adding boron, magnesium, sodium, fluorine, and aluminum were obtained using the sol-gel method. Gel-derived materials were produced in the pellet form obtained by compression of powders as well as in coatings on glass slides. The materials obtained were examined in vitro with regard to the ability of calcium phosphate layer to form on the material surface as the result of contact with simulated body fluid (SBF). SBF pH changes and calcium solubility in this solution were determined and scanning electron microscopy, energy-dispersive X-ray analysis, and infrared spectroscopy studies were conducted before and after contact of the materials with SBF. The gels modified by aluminum were amorphous, whereas the sodium and fluorine additives promoted the bulk crystallization of gel-derived materials. The ability of calcium phosphates to crystallize on the surface of gel-derived materials depended only slightly on the types of additives applied, and the character of this dependence was different from that observed in melted glasses. Moreover, to estimate the biocompatibility of gel-derived coatings, we examined the proliferation, collagen synthesis, adhesion, and morphology of fibroblasts (NRK cells) cultured in the presence of gel-derived materials. The results of these experiments showed that none of the tested materials significantly reduced any cell function.

Animals↗
PubMed1994

Inhibition of collagen hydroxylation by lithospermic acid magnesium salt, a novel compound isolated from Salviae miltiorrhizae Radix.

We have screened several chinese medicinal herbs for the presence of antifibrotic agents. An aqueous extract of Salviae miltorrhizae Radix was found to inhibit collagen secretion by human skin fibroblasts without affecting DNA or noncollagen protein synthesis. We have subsequently purified the material exhibiting the inhibitory activity and identified it as magnesium lithospermate. From its chemical structure this compound was predicted to be an inhibitor of the post-translational modifying enzymes prolyl and lysyl hydroxylases in collagen biosynthesis. Accordingly, it decreased the extent of prolyl and lysyl hydroxylations in collagen by approx. 50%. Added to cell extracts it inhibited both prolyl and lysyl hydroxylase activities, but only lysyl hydroxylase activity when added to intact cells. Oral administration of this compound to mice led to a significant reduction of prolyl hydroxylation in newly-synthesized skin collagen. This naturally-occurring compound thus offers a potential means for treating fibrotic diseases, such as systemic scleroderma and keloid.

Animals↗
PubMed1998

Short time effect of Chemiron (a combination iron preparation), single iron, and different magnesium salts on plasma. Magnesium concentration during early pregnancy in Nigerian women. A preliminary report.

Maternal magnesium requirements increase during pregnancy because of the synthesis of new tissue--both fetal and maternal. Magnesium takes part in almost 300 enzymatic reactions in the human body and regulates membrane permeability and protein bio-synthesis by promoting initiation and dissociation factors. The absorption velocity of magnesium differs from one tissue to another in animal experiments. It is highest in the liver, kidney, heart and is low in skeletal muscle, the brain and erythrocytes. It obeys and follows the Michaelis-Menten Kinetic law. 15 mmol of magnesium is consumed daily depending on the types of food takenin. The main sources of magnesium are vegetables and meats. Many Nigerian women are not able to afford enough of these. The amount of magnesium reabsorbed depends on the magnesium intake and not on magnesium needed which is about 10-40% of the intake. In this study, we examined the short-term effect of magnesium asphat HCL (614.18 mgMG), magnesium diasporal (magnesium citrate 610 mg + magnesium laevalitat 30 mg = 100 mg magnesium = 8.2 mval), ferrous gluconate (300 mg) plus folic acid and chemiron, a new combination hematinic agent (ferrous fumarate 300 mg, folic acid 5 mg, vitamin B12 10 mg, vitamin C 25 mg, magnesium sulfate 0.3 mg and zinc sulfate 0.3 mg) on plasma magnesium concentration during early pregnancy in Nigerian women. Significant increases of plasma magnesium concentrations were found in these groups (magnesium asphat HCL, 0.83 +/- 0.12 to 0.96 +/- 0.14 mmol/l, magnesium diasporal 0.843 +/- 0.14 to 0.891 +/- 0.14 mmol/l and chemiron 0.848 +/- to 0.866 +/- 0.16 mmol/l after five days. The ferrous gluconate and folic acid treated group showed no significant changes. This study shows that a chemiron supplement leads to increased magnesium plasma levels whereas ferrous gluconate and folic acid do not. These results suggest that the low level of magnesium is a normal physiological adjustment of pregnancy and that iron supplementation does not influence this unless magnesium salt is given.

Adult↗
PubMed1999

Characterization of bis(isoorotato)diaquamagnesium(II) dihydrate: a potentially useful complex for magnesium supplementation.

The synthesis and crystal structure of a new Mg(II) complex of stoichiometry [Mg(isoor)2(H2O)2].2H2O, where isoor is the monoanion of 5-carboxyuracil (isoorotic acid), are reported. The structure, solved by single-crystal X-ray diffractometry, shows that it crystallizes in the triclinic space group P(-1) with Z = 1. The electronic, IR and Raman spectra of the complex are briefly discussed. Its thermal behavior was also investigated by means of thermal gravimetry (TG) and differential thermal analysis (DTA) measurements in an oxygen atmosphere. Dissolution studies support the usefulness of the compound for magnesium supplementation.

Crystallography, X-Ray↗