Variations In Magnesium Concentration Research Articles

Variations in Magnesium Concentration Are Associated with Increased Mortality: Study in an Unselected Population of Hospitalized Patients.

Dysmagnesemia is a serious disturbance of microelement homeostasis. The aim of this study was to analyze the distribution of serum magnesium concentrations in hospitalized patients according to gender, age, and result of hospitalization. The study was conducted from February 2018 to January 2019 at the Central Clinical Hospital in Warsaw. Laboratory test results from 20,438 patients were included in this retrospective analysis. When a lower reference value 0.65 mmol/L was applied, hypermagnesemia occurred in 196 patients (1%), hypomagnesemia in 1505 patients (7%), and normomagnesemia in 18,711 patients (92%). At a lower reference value of 0.75 mmol/L, hypomagnesemia was found in 25% and normomagnesemia in 74% of patients. At a lower reference value of 0.85 mmol/L, hypomagnesemia was found in 60% and normomagnesemia in 39% of patients. Either hypo- or hyper-magnesemia was associated with increased risk of in-hospital mortality. This risk is the highest in patients with hypermagnesemia (40.1% of deaths), but also increases inversely with magnesium concentration below 0.85 mmol/L. Serum magnesium concentration was not gender-dependent, and there was a slight positive correlation with age (p < 0.0001, r = 0.07). Large fluctuations in serum magnesium level were associated with increased mortality (p = 0.0017). The results indicate that dysmagnesemia is associated with severe diseases and generally severe conditions. To avoid misdiagnosis, an increase of a lower cut-off for serum magnesium concentration to at least 0.75 mmol/L is suggested.

Why spatial and temporal variations in magnesium in drinking water are important considerations when magnesium in drinking water is used as exposure in health related studies

TPS 931: Water and foodborne chemicals, Exhibition Hall, Ground floor, August 28, 2019, 3:00 PM - 4:30 PM Background and objectives The aim of the study was to investigate the stability of magnesium, sodium, potassium and calcium in drinking water and thereby be able to improve exposure estimates in future health related studies. Focusing on magnesium, the objective was to investigate annual temporal and spatial variations in magnesium in drinking water for the period 1980 – 2017 in Denmark. Methods: Public waterworks were linked to water supply areas by spatial joins and the number of addresses within each water supply area was calculated. For each public water supply area (WSA), linear regression and change point analyses were used to analyse the temporal variations in magnesium concentration. Afterwards, each WSA was categorized according to the analysed temporal trend in magnesium concentration. Spatial variations were analysed using spatial scan statistics in SatScan. Results: The study included 62,941 magnesium analyses, covering 2,539 WSAs, 99.5 percent of the Danish addresses, and 417 to 2,106 samples per year. Mean magnesium concentration = 12.1 mg/L and median = 9.8 mg/L. The magnesium concentration was constant for 40 percent of the WSAs, covering 18 percent of the Danish addresses. Two statistically significant clusters were detected, a hotspot (18.2 mg/L, p-value <=0.001) in the eastern part of Denmark and a cold spot (8.1 mg/L, p-value <= 0.001) in the western part of Denmark. Conclusion: A mean magnesium concentration, covering 37 years, is adequate as exposure estimate for two fifths of the WSAs, though only covering about one fifth of the addresses in Denmark. Furthermore, the magnesium concentration in drinking water was clustered at a regional scale. In future health related studies, it is therefore recommended, that magnesium exposure estimates are not only based on a single mean value, but annual temporal and spatial variations should also be included.

Ways of increasing the magnesium content in sward from a long-term fertilizer experiment

The paper discusses fluctuations, and their underlying causes, in the magnesium content of meadow sward from a fertilizer experiment set up on a mountain meadow in 1968. The fertilization experiment comprised 8 different treatments, with the following modifications: liming, magnesium and microelement fertilization and a change in the sward use made during the experiment so as to regenerate the sward and to improve the yielding potential. In the initial period, magnesium concentrations in the sward were assessed using the ASS technique after dry mineralization of samples and dissolution of the residue in diluted nitric acid. Later, the ICP technique was applied, including an internal reference sample for the methods. The cultivation measures caused variations in magnesium concentrations in the sward, depending on a number of factors, among which direct fertilization was not the most significant one. For example, the ambient temperature during the plant growing season strongly influenced the magnesium content, irrespectively of a cut. There was no effect of rainfall of the magnesium content, although atmospheric precipitation was able to raise considerably the charge of this element. In the second cut and under neutral soil pH, higher concentrations of magnesium were noted in the sward. This could have resulted from either the lower second swath yielding or the optimum conditions for the uptake of magnesium by the sward that occurred during its growth. The investigation results failed to provide an unambiguous answer to the question whether magnesium fertilization affected the concentrations of this element. Nonetheless, in order to maintain the production of valuable fodder it is essential to return systematically the elements taken up with plant yield to the soil. In intensively managed meadows, amounts of magnesium removed from the soil with the harvested biomass can be as high as several kilograms per hectare.

Crystallographic contribution to the vital effect in biogenic carbonates Mg/Ca thermometry

ABSTRACTThe processes involved in vital effects, defined as biological processes overriding environmental signals, are not well understood and this hampers the interpretation of environmental parameters such as seawater temperature. Insufficient knowledge is available about changes in physico-chemical parameters, in particular those related to crystallography, associated with biomineral formation and emplacement. This paper assesses the influence of crystallography on Mg2+ concentration and distribution in calcite biominerals of bivalved marine organisms, mussels and rhynchonelliform brachiopods, and considers the implications for Mg/Ca thermometry. In the mussel Mytilus edulis, changes in Mg2+ are not associated with crystallography; but in the brachiopod Terebratulina retusa, increases in Mg2+ concentrations (∼0·5–0·6 wt. ) are associated with the {0001 planes of calcite biominerals. A comparison between mussels and brachiopods with avian eggshells, which form at constant ambient temperature, also reveals that there is at least a common 0·1 wt. variation in magnesium concentration in these calcite biomineral systems unrelated to temperature or crystallography. Results demonstrate that the integration of contextual crystallographic, biological and chemical information may be important to extract accurate environmental information from biominerals.

Magnesium and phosphorus distribution in the avian eggshell

Magnesium and phosphorus are major inorganic constituents of the avian eggshell. The Mg/Ca ratio has been used as a palaeothermometer in a range of calcite biominerals. Eggshells provide the opportunity to examine the Mg/Ca ratio of a calcite biomineral produced in a constant temperature environment. Mg distribution is not constant throughout the shell, decreasing from nucleation until after fusion of the mammillary caps and then increasing to termination. This indicates that temperature of deposition is not the only factor controlling the Mg content of this biomineral system. There is a greater increase in magnesium concentration in the outer region of eggshells from older birds. The variation in magnesium concentration does not appear to correlate with organic content. Phosphorus occurs in the outer quarter of the eggshell and rises to termination and is therefore not confined to cuticular vesicles.

Quantitative magnesium analysis of mononuclear cells: Electron probe x‐ray microanalysis and atomic absorption spectroscopy methods compared

AbstractWe quantitated magnesium concentration of pooled human peripheral mononuclear blood cell populations and individual human peripheral mononuclear blood cells by flame atomic absorption spectroscopy and electron probe X‐ray microanalysis, respectively. We found no significant difference (p &gt; .1) between the mean cell magnesium concentrations (61.4 ± 10.9 and 51.2 ± 11.2 mmol/kg dry weight) determined by electron probe X‐ray microanalysis and flame atomic absorption spectroscopy, respectively. Using electron probe X‐ray microanalysis, we found a 20% variation in magnesium concentration among individual cells. The cell magnesium concentration was independent of cell size, but the cell magnesium content increased with cell volume. We discuss the analytical limitations and artifacts of flame atomic absorption spectroscopy and electron probe X‐ray microanalysis for determination of mononuclear blood cell magnesium.

A sample preparation for quantitative determination of magnesium in individual lymphocytes by electron probe X‐ray microanalysis

We present a sample preparation method for measuring magnesium in individual whole lymphocytes by electron probe X-ray microanalysis. We use Burkitt's lymphoma cells in culture as the test sample and compare X-ray microanalysis of individual cells with atomic absorption analysis of pooled cell populations. We determine the magnesium peak-to-local continuum X-ray intensity ratio by electron probe X-ray microanalysis and calculate a mean cell magnesium concentration of 39 +/- 19 mmol/kg dry weight from analysis of 100 cells. We determine a mean cell magnesium concentration of 34 +/- 4 mmol/kg dry weight by atomic absorption analysis of pooled cells in three cell cultures. The mean cell magnesium concentrations determined by the two methods are not significantly different. We find a 10% coefficient of variation for both methods of analysis and a 30% coefficient of variation in magnesium concentration among individual cells by electron probe X-ray microanalysis. We wash cells in ammonium nitrate for microanalysis or in buffered saline glucose for atomic absorption analysis. We find cells washed in either solution have the same cell viability (85%), recovery (75%), cell volume (555 microns 3) and cytology. We air dry cells on thin film supports and show by magnesium X-ray mapping that magnesium is within the cells. We conclude that: our microanalysis cell preparation method preserves whole intact lymphocytes; there is no systematic difference in results from the two methods of analysis; electron probe X-ray microanalysis can determine the variation in magnesium concentration among individual cells.

Radiaxial Calcite in Lower Miocene Strata, Subsurface Enewetak Atoll

ABSTRACT Radiaxial calcite is abundant in Lower Miocene strata, 377-819 m deep on Enewetak Atoll. These radiaxial crystals have equant, bladed, and fibrous morphologies and occur as isopachous crusts 0.05-2.0 mm thick. Radiaxial terminations consist of fibrous subcrystals bundled together into larger acute, obtuse, or rounded shapes. Enewetak radiaxial calcite ranges from clear to very inclusion-rich. Most inclusions are microcavities caused by organic infestations (Videtich 1985). Alternating bands of inclusion-rich and inclusion-poor calcite mimic existing termination patterns. Radiaxial calcites fill intergranular pores, sponge borings, fractures, and aragonite molds. Aragonite has been pervasively dissolved from the Lower Miocene strata containing radiaxial calcite. Banded radiaxial calcit can be traced from intergranular pores into aragonite molds. Radiaxial calcites have a mean magnesium concentration of 3.2 mole % MgCO3 with a range from 1.6 to 11.1 mole % MgCO3. Inclusion-rich bands and more deeply buried radiaxial calcite tend to have lower magnesium concentrations. Enewetak radiaxial calcite has 13C values of +1.3 to +2.5 (PDB) and 18O values of -1.8 to +0.4 (PDB). Petrographic and stable isotopic data are consistent with precipitation of radiaxial calcite in its present form directly from seawater. Precipitation of radiaxial calcite after aragonite dissolution indicates precipitation distinctly after deposition, probably in a burial environment. Dissolution of aragonite by deep marine water is suggested by: 1) abundant marine cement associated with aragonite dissolution; 2) a lack of meteoric cements associated with aragonite dissolution; and 3) no evidence of subaerial exposure in Lower Miocene strata between 400 and 819 m. Modern Pacific Ocean water is undersaturated with respect to aragonite at depths where aragonite dissolution is observed (375-850 m). Tidal fluctuations and temperature profiles indicate that Lower Miocene strata containing radiaxial calcite are in open communication With modern Pacific Ocean water. Therefore, aragonite dissolution and radiaxial cementation are interpreted as having occurred in seawater (undersaturated with respect to aragonite) circulating through the atoll. Variations in magnesium concentration in Enewetak radiaxial calcite may be the result of original heterogeneity or differential loss of magnesium during later diagenesis in seawater. The first alternative is preferred. Precipitation of radiaxial calcite at different rates (at different degrees of saturation) could cause variable magnesium concentrations. More deeply buried radiaxial calcite may have precipitated more slowly in deeper, less supersaturated water, resulting in lower magnesium concentrations. Likewise, slower rates of precipitation may have resultedin organic infestations and lower magnesium concentrations in inclusion-rich bands. Enewetak radiaxial calcites suggest that two factors might be critical to development of radiaxial fabric: 1) precipitation at fluctuati g rates, and 2) formation in waters undersaturated with respect to aragonite.

Variation in the magnesium concentration of ryegrass plants

Abstract 415 ryegrass genotypes, collected from pastures on soils of different exchangeable magnesium concentration, together with 160 genotypes from 8 commercial cultivars were examined for variation in herbage magnesium concentration. There was no evidence for ecotypic or cultivar differences in magnesium concentration, but there was substantial variation within all populations. Magnesium concentrations up to 0.552% of DM were found. When a high magnesium selection of perennial ryegrass was tested further, indications of genetic control of herbage magnesium concentrations were obtained. Within this selection there were positive correlations between cOl1centrations of magnesium and potassium, calcium, iron, copper, manganese, and zinc, but a significant negative correlation with sodium. It is concluded that there is scope for selection of high-magnesium ryegrass, but sodium content would have to be monitored.

Fluctuations in total calcium and magnesium in the plasma and uterine fluid of the domestic fowl.

Synopsis Fluctuations in calcium and magnesium were measured in the shell gland fluid and blood from the inferior oviducal vein of the domestic fowl throughout the laying cycle. It was concluded that: The variations in calcium concentration reflected both the known uptake of this ion by the albumen and medullary bone formation and destruction. The variations in magnesium concentration did not parallel the changes in calcium concentration. Magnesium was released into the blood during medullary bone formation.

Effect of the magnesium concentration in the extracting medium on the polyribosome content and the cell-free amino acid incorporating ability of extracts of logarithmic phase cells of a Bacillus sp.

1. This investigation is concerned with the effect of variation in magnesium concentration, at constant monovalent cation concentration, on the distribution of ribosomal components in and on the cell-free amino acid incorporating abilities of extracts of Bacillus amyloliquefaciens disrupted under considerable shear and disrupted gently, with and without depletion of mRNA by actinomycin D in the latter case. 2. Extracts containing mRNA-depleted ribosomes which no longer had the ability to incorporate amino acids into protein contained a small basal level of faster than 70 S sedimenting material. The amount of this material was found to be Mg 2+ dependent and is thought to represent aggregates of ribosomes containing no mRNA. 3. Preparations of cells disrupted in the presence of a low Mg 2+ concentration. by shear at 2.5 mM Mg 2+ or gently with lysozyme at 1.25 mM Mg 2+, contained 50-S and 30-S particles which did not associate on increasing the Mg 2+ to 10 mM but nevertheless showed considerable ability to incorporate amino acids. 4. The effect of Mg 2+ on the polyribosomes in extracts of cells disrupted under mild conditions showed that in the range 5 to 10 mM there was preservation of maximal cell-free amino acid incorporating ability and interconvertibility of ribosomal distribution patterns, below 5 mM Mg 2+ both incorporating ability and faster than 70 S sedimenting material was lost. 5. Extracts of cells disrupted by shear under conditions which preserved the maximal cell-free incorporating ability incorporated approximately half as much 14C-labelled amino acid as preparations lysed gently under optimal conditions. 6. When a preparation was isolated in the presence of 5 mM Mg 2+ it showed identical kinetics of amino acid incorporation, in the presence of 10 mM Mg 2+, to a preparation isolated in 10 mM Mg 2+. However, when the incorporation was examined at 5 mM Mg 2+ the same preparation incorporated amino acid to only 20% of the 10 mM Mg 2+ level.

Effects of morphine on the hormonal control of metabolism—IV: Morphine-induced changes in sensitivity of the glucose-uptake system of muscle to extracellular magnesium

The effects of morphine, adrenaline, and hydrocortisone on uptake of glucose from media of different magnesium content by diaphragm of normal and of chronically morphinized rats have been studied in vitro. The effects of morphine, of adrenaline, and of hydrocortisone on normal diaphragm are each dependent upon the presence in the medium of magnesium within a limited range of concentration. The basic rate of glucose-uptake by chronically morphinized diaphragm, unlike that of normal diaphragm, is not influenced by changes in the magnesium content of the medium and the effect of morphine is not changed by variations in magnesium concentration from 0 to 2.5 mM. Chronically morphinized diaphragm is insensitive to hydrocortisone (3.85 × 10 −6 M) and sensitivity is not restored by changes in magnesium concentration. Chronically morphinized diaphragm is insensitive to adrenaline (3.85 × 10 −6 M) in the standard medium (1.25 mM Mg), but sensitivity is restored by raising the magnesium content of the medium to a level (2.5 mM) which abolishes the effect of the hormone on normal diaphragm.

Ribosome structures revealed by negative staining subcellular fractions from a crystalline ribonucleoprotein body

1. 1. A fractionation procedure has been developed which utilizes ascorbic acid as an anti-oxidant and variations in magnesium concentration to control the state of aggregation of RNA containing particles. The procedure was used to obtain free ribosomes and particles from the chromatoid body. 2. 2. Electron microscopic evidence is presented to support the hypothesis that the chromatoid body consists of a crystalline mass of particles in the early cyst stage of the life cycle. 3. 3. Negative staining of the two particulate fractions revealed a diversity of particle size varying from 150–660 Å in diameter. This diversity of size is shown to be due to the aggregation in different combinations of two ribosome-like particles of 150 and 250 Å. 4. 4. Preliminary results of analysis of sedimentation rates of both untreated and citrate treated chromatoid body particles indicate the differing states of aggregation of ribosome-like particles. 5. 5. The results support the hypothesis that the chromatoid body represents a crystalline store of ribosomes and are incompatible with a virus interpretation of the nature of the body.

Ultracentrifugal Studies on Ribonucleoprotein from Rat Liver Microsomes

The ribonucleoprotein of rat liver microsomes requires some dialyzable substance for stability (Z), and can be purified by repeated washings with liver dialysate (3). Since a similar ribonucleoprotein from yeast is stabilized by low concentrations of magnesium or calcium (4,5), it seemed probable that dibasic ions were the effective constituents of the liver dialysate. Dilute solutions of magnesium salts can be substituted for the liver dialysate. The magnesium concentration, however, is critical; too much magnesium causes aggregation and precipitation of the ribonucleoprotein, whereas too little leads to dissociation into smaller units. The optimal concentration of magnesium depends on the pH and on the nature and concentration of the other ions in the solution. In this paper an improved method of purification is described, in which the RNPl is washed in a buffer containing magnesium chloride, and further purified by precipitation with barium acetate. The changes in the structure of the RNP which result from variations in magnesium concentration, pH, and the ionic composition of the solution, have been followed in the analytical ultracentrifuge.

Relationship of changes in ionic concentrations to the augmentation produced by extra contractions in isolated mammalian ventricular muscle.

Studies performed on the isolated cat papillary muscle show that at calcium levels which reduce to about one-half the force of regularly spaced contractions, the extent of augmentation produced by a single interpolated beat is unchanged. Increase in potassium concentration produced a slight decrease in the augmentation effect. Variation in magnesium concentration had no effect. Changes from bicarbonate to phosphate buffer lowered the force of the regularly spaced contractions but did not change the degree of augmentation. It appears that the augmentation phenomenon probably cannot be explained on the basis of loss of intracellular potassium.