Role Of Magnesium Research Articles

Abstract 1199: Low Serum Magnesium Concentrations Predict Increase in Left Ventricular Mass Over Five Years Independently of Common Cardiovascular Risk Factors: Study of Health in Pomerania

Increased cardiac left ventricular mass (LVM) is a significant predictor of adverse cardiovascular events. Experimental studies suggest a pathophysiological role of magnesium (Mg ++ ) in the development of arterial hypertension and left ventricular hypertrophy (LVH). Subjects, aged 45 – 79 years, from the population-based, epidemiological, longitudinal “Study of Health in Pomerania” with complete echocardiographic data (n = 1 348 after exclusion of aortic valve disease) were grouped into five quintiles according to serum Mg ++ at baseline (0.790±0.003 mmol/l, mean±SEM). In the lowest Mg ++ -quintile (Mg ++ <<26>0.73 mmol/l), LVM (187.4±3.1 g at baseline) increased by 14.9±1.2 g over the following five years, while in the highest Mg ++ -quintile (Mg ++ <<0.85 mmol/l) LVM (186.7±3.4 g at baseline) decreased by −0.5±2.8 g (p<0.0001 between quintiles). After five years, LVM was significantly higher in the lowest Mg ++ -quintile (LVM: 202.2±3.4 g) in comparison to the highest Mg ++ -quintile (187.2±3.5 g, p<0.003 between quintiles). Mg ++ inversely correlated with the difference in LVM over five years (p<0.0001, females: p<0.002, males: p<0.024) and also with differences in Sokolow-Lyon-index over five years (p<0.01). Unlike age, gender, presence of hypertension or diabetes mellitus, body mass index, smoking status, renal function, high-sensitive C-reactive protein and use of various antihypertensive drugs including diuretics, only Mg ++ (p<0.0001), pulse pressure (p<0.002) and use of β-blockers (p<0.04) were identified as independent predictors of difference in LVM over five years. Hypomagnesemia is one of the strongest predictors of increase in LVM over the following five years. It should initiate decisive preventive measures in subjects prone to developing LVH.

Simultaneous, Bilateral Pathological Displaced Intracapsular Hip Fractures Occurring Spontaneously Secondary to Osteomalacia of Hypomagnesemic Origin: A Case Report and Review of the Literature.

Spontaneous fractures involving both of the femoral necks simultaneously are exceedingly rare events. We report a case of an elderly female who presented after breaking both femoral necks following a trivial fall, initially diagnosed as age-related osteoporosis. Both the hips were treated by hemiarthroplasty. The diagnosis was revised to vitamin D-resistant osteomalacia secondary to hypomagnesemia after histopathological confirmation and further investigations. We examine the different etiological factors and mechanisms operating in the causation of this rare injury and explore the possible role of magnesium in the pathogenesis of osteomalacia. Fractures may remain occult until late, leading to increased morbidity and mortality. The value of an early MRI is recapitulated, with emphasis placed on prevention and early fixation.

Role of magnesium in carbon partitioning and alleviating photooxidative damage

Magnesium (Mg) deficiency exerts a major influence on the partitioning of dry matter and carbohydrates between shoots and roots. One of the very early reactions of plants to Mg deficiency stress is the marked increase in the shoot-to-root dry weight ratio, which is associated with a massive accumulation of carbohydrates in source leaves, especially of sucrose and starch. These higher concentrations of carbohydrates in Mg-deficient leaves together with the accompanying increase in shoot-to-root dry weight ratio are indicative of a severe impairment in phloem export of photoassimilates from source leaves. Studies with common bean and sugar beet plants have shown that Mg plays a fundamental role in phloem loading of sucrose. At a very early stage of Mg deficiency, phloem export of sucrose is severely impaired, an effect that occurs before any noticeable changes in shoot growth, Chl concentration or photosynthetic activity. These findings suggest that accumulation of carbohydrates in Mg-deficient leaves is caused directly by Mg deficiency stress and not as a consequence of reduced sink activity. The role of Mg in the phloem-loading process seems to be specific; resupplying Mg for 12 or 24 h to Mg-deficient plants resulted in a very rapid recovery of sucrose export. It appears that the massive accumulation of carbohydrates and related impairment in photosynthetic CO2 fixation in Mg-deficient leaves cause an over-reduction in the photosynthetic electron transport chain that potentiates the generation of highly reactive O2 species (ROS). Plants respond to Mg deficiency stress by marked increases in antioxidative capacity of leaves, especially under high light intensity, suggesting that ROS generation is stimulated by Mg deficiency in chloroplasts. Accordingly, it has been found that Mg-deficient plants are very susceptible to high light intensity. Exposure of Mg-deficient plants to high light intensity rapidly induced leaf chlorosis and necrosis, an outcome that was effectively delayed by partial shading of the leaf blade, although the Mg concentrations in different parts of the leaf blade were unaffected by shading. The results indicate that photooxidative damage contributes to development of leaf chlorosis under Mg deficiency, suggesting that plants under high-light conditions have a higher physiological requirement for Mg. Maintenance of a high Mg nutritional status of plants is, thus, essential in the avoidance of ROS generation, which occurs at the expense of inhibited phloem export of sugars and impairment of CO2 fixation, particularly under high-light conditions.

Role of Magnesium in Soda-Lime Glasses: Insight into Structural, Transport, and Mechanical Properties through Computer Simulations

The role of Mg in soda-lime glasses was elucidated by classical molecular dynamics (MD) simulations. The effect of the replacement of CaO for MgO on the structure, transport, and elastic properties of a series of glasses with compositions 15Na2O·(10 − x)CaO·xMgO·75SiO2 (x = 0, 5, and 10 mol) was studied. Different structural roles were found for the Ca and Mg ions. The former, coordinated by six oxygen atoms, acts as a network modifier, while the latter, four-fold coordinated, participates in the silica network. Consequently, Na ion diffusion is favored by the replacement of MgO for CaO in these glasses, as shown by variation in the computed diffusion coefficients and activation energy of the process in the series of glasses studied. Moreover, the consequences of these structural modifications on the elastic properties (Young’s modulus, shear modulus, bulk modulus, Poisson’s ratio, and compressibility) of the glasses were evaluated by means of energy minimization techniques carried out on the structures o...

Magnesium and the control of cell proliferation: looking for a needle in a haystack.

Experimental evidence supports the important role of magnesium in the process of cellular proliferation, even though cell magnesium homeostasis is not completely clarified. We were the first to describe some molecular characteristics of the magnesium-dependent regulation of the cell cycle, and others proposed a mechanism for the magnesium-dependent regulation of protein synthesis occurring in the early phases of cell proliferation. We will attempt to relate such mechanisms with pathologic conditions whereby cell proliferation is severely disregulated, as in the case of tumors. It is interesting to note that recently some efforts have been made to correlate magnesium transport systems with its functions within the cells. Few, but stimulating new data are emerging which relate molecularly defined ion channels with magnesium homeostasis and its functions. Old and new data are now being merged and corroborated by diverse experimental approaches including molecular genetics, proteomics, electrophysiology and biochemistry. This, together with the development of new techniques to measure cell magnesium content and distribution, will hopefully pave the way to unravel the intimate mechanisms of such an essential though undefined metabolic regulator. New and deeper appreciation of magnesium homeostasis will help in delineating the key role of this cation in the regulation of normal or pathologic cell proliferation.

Role of Magnesium in Mitigating Membrane Fouling in Membrane Bioreactors

Role of Magnesium in Mitigating Membrane Fouling in Membrane Bioreactors

The role of magnesium on the stability of crystalline sepiolite structure

Sepiolite is a hydrate magnesium silicate special clay mineral. Some of the specific properties of this silicate are its large specific surface (about 320 m 2/g) together with a very reduced ion exchange capacity. Additionally, it is possible to leach the magnesium cations at the octahedral layer by acid attack, increasing the specific surface area up to the limit of the collapse of the structure. In the present investigation, we have found that the crystalline framework collapses when the fraction of leached Mg 2+ is greater than or equal to 0.33. Before the collapse it is possible to obtain sepiolite with different substituted metallic cations into the octahedral sites. As an example, the optimal composition of Ni–sepiolite was obtained after the lixiviation by acid attack at pH 0 for 1 h without the collapse of structure.

Cell (patho)physiology of magnesium

There is an unsettled debate about the role of magnesium as a 'chronic regulator' of biological functions, as opposed to the well-known role for calcium as an 'acute regulator'. New and old findings appear to delineate an increasingly complex and important role for magnesium in many cellular functions. This review summarizes the available evidence for a link between the regulation of intracellular magnesium availability and the control of cell growth, energy metabolism and death, both in healthy and diseased conditions. A comprehensive view is precluded by technical difficulties in tracing magnesium within a multicompartment and dynamic environment like the cell; nevertheless, the last few years has witnessed encouraging progress towards a better characterization of magnesium transport and its storage or mobilization inside the cell. The latest findings pave the road towards a new and deeper appreciation of magnesium homoeostasis and its role in the regulation of essential cell functions.

Kinetics and Mechanism of Ni(II) Chelation in Model and Real Solutions of Xylem Sap of Quercus ilex

AbstractThe kinetics of formation and dissociation of Ni(II) complexes with oxalic and citric acids was studied by cyclic voltammetry in model solutions of xylem sap of Q. ilex (the dominant tree growing on serpentine soils of Northeast Portugal) using representative concentrations, pH and ionic strength. The role of magnesium on complex formation was analyzed from solutions where Mg is present at concentration levels found in the xylem sap of Q. ilex growing on both nonserpentine and serpentine soils. Kinetics studies were also done in diluted solutions of real xylem sap samples, spiked with increasing amounts of magnesium. The values obtained for the apparent rate constants were those anticipated by the proposed model. To test the validity of the methodology and mechanisms, formation rate constants, kf (M−1 s−1) of Ni(II) complexes with citrate and oxalate were evaluated that compare with the values from Eigen mechanism.

Role of Magnesium on Anodic Activation of Aluminum Alloys Caused by Segregation of Trace Element Lead

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Magnesium's role in pediatric asthma

Magnesium's role in pediatric asthma

The role of magnesium in hydrolysis of triphosphates in water: Quantum mechanical/molecular mechanical modeling

The mechanism of hydrolysis of deprotonated methyl triphosphate (MTP) to methyl diphosphate (MDP) and inorganic phosphate (Pi) in water clusters in the presence and absence of magnesium cations has been modeled. Modeling has been performed by the effective fragment potential-based quantum mechanical/molecular mechanical method. The energies and energy derivatives in the quantum subsystem including MTP, reacting water molecules, and Mg2+ has been calculated at the density functional theory (B3LYP) level, whereas water-water interactions have been described by the TIP3P model potential. The minimum-energy path for the reaction MTP + H2O → MDP + Pi is consistent with a two-stage dissociative process in the absence of Mg2+ and with a one-stage mechanism in the presence of Mg2+.

Magnesium in the treatment of asthma

To provide an update of recent research on the role of magnesium in the management of asthma. Further evidence has been published that long-term oral magnesium supplementation does not lead to improved control in adult asthma. In contrast, updated meta-analyses of randomized controlled trials have confirmed the efficacy of both intravenous and inhaled (as an adjuvant to salbutamol nebulizer solution) magnesium therapy in severe asthma. This conclusion is still limited by the paucity of randomized controlled trials, however, with many issues yet to be firmly established, such as the efficacy in different patient subgroups, the dose regimes, and the optimal method of administration. International guidelines currently recommend the use of intravenous magnesium in severe asthma, and there is evidence that this approach is now widely used in emergency departments in North America. This audit also illustrated the emerging unregistered use of nebulized magnesium/salbutamol solution. Further investigation of the efficacy and safety of magnesium in severe asthma is now urgently required to determine its role in this clinical situation. The research community must heed the call for more research that is being made by funding agencies dealing with this area.

Role of magnesium in neural process of rat cultured neurons

Role of magnesium in neural process of rat cultured neurons

The role of magnesium as an adjuvant during general anaesthesia

Magnesium sulphate is used extensively in the treatment of eclampsia, and is also used to treat refractory arrhythmias, asthma, myocardial ischaemia and acute respiratory failure. We studied the interaction between magnesium sulphate and the anaesthetic agents propofol, rocuronium bromide and fentanyl citrate. This randomised, double blind study was conducted in 50 patients. The magnesium group A (n = 25) received 30 mg x kg(-1) magnesium sulphate before induction of anaesthesia and 10 mg x kg(-1) continuously intra-operatively until the end of surgery. Group B (n = 25) received the same volume of isotonic saline. Propofol, rocuronium and fentanyl infusions were started and the patients lungs' were ventilated with 33% oxygen in nitrous oxide. Anaesthetic depth was maintained at a bispectral index value of between 40 and 60. Muscle relaxation was maintained at a train-of-four count of 1 throughout surgery using neuromuscular monitoring. The fentanyl infusion was titrated to haemodynamic variables: heart rate and blood pressure. We concluded that magnesium sulphate has anaesthetic, analgesic and muscle relaxation effects and significantly reduces the drug requirements of propofol, rocuronium and fentanyl during anaesthesia.

A Randomized Controlled Study of Effects of Dietary Magnesium Oxide Supplementation on Bone Mineral Content in Healthy Girls

The role of magnesium (Mg) as a determinant of bone mass has not been extensively explored. Limited studies suggest that dietary Mg intake and bone mineral density are correlated in adults, but no data from interventional studies in children and adolescents are available. We sought to determine whether Mg supplementation in periadolescent girls enhances accrual of bone mass. We carried out a prospective, placebo-controlled, randomized, one-year double-blind trial of Mg supplementation. The study was conducted in the Clinical Research Centers at Yale University School of Medicine. Healthy 8- to 14-yr-old Caucasian girls were recruited from community pediatricians' offices. Dietary diaries from over 120 volunteers were analyzed, and those with dietary Mg intake of less than 220 mg/d were invited to participate in the intervention. Magnesium (300 mg elemental Mg per day in two divided doses) or placebo was given orally for 12 months. The primary outcome measure was interval change in bone mineral content (BMC) of the total hip, femoral neck, Ward's area, and lumbar spine (L1-L4) after 12 months of Mg supplementation. Significantly increased accrual (P = 0.05) in integrated hip BMC occurred in the Mg-supplemented vs. placebo group. Trends for a positive Mg effect were evident in the pre- and early puberty and in mid-late puberty. Lumbar spinal BMC accrual was slightly (but not significantly) greater in the Mg-treated group. Compliance was excellent; 73% of capsules were ingested as inferred by pill counts. Serum mineral levels, calciotropic hormones, and bone markers were similar between groups. Oral Mg oxide capsules are safe and well tolerated. A positive effect of Mg supplementation on integrated hip BMC was evident in this small cohort.

Serum magnesium profile in heroin addicts: according to psychiatric comorbidity.

Psychiatric comorbidity in heroin addiction can modify both the biological pattern and clinical course of this disorder. Because of the role of magnesium in neurotransmission and its specific patterns in some psychiatric conditions, such as depression and schizophrenia, we studied a sample of heroin dependent subjects, with and without psychiatric comorbidity. A sample of 162 drug addicts (123 men and 39 women, mean age 32.3 +/- 6.7) was diagnosed for the presence of psychiatric comorbidity with DSM IV criteria. They were subsequently divided in 4 subgroups: No comorbidity, Anxiety Disorders, Mood Disorders, Personality Disorders. Differences in serum magnesium level between the groups were analysed with the Anova method, with age as covariate. Results show that serum Mg++ levels are significantly higher in patients with heroin dependence and personality disorders compared to patients with depression comorbidity and without comorbidity. Psychiatric codiagnosis significantly modifies Mg++ levels in this drug dependent sample. Gender modifies Mg levels in no comorbid subjects so that females show significantly lower Mg++ levels compared to males. The presence of psychiatric comorbidity abates this difference.

Ageing, hippocampal synaptic activity and magnesium.

Ageing is associated with a general decline in physiological functions. Amongst the different aspects of body deterioration, cognitive impairments, and particularly defects in learning and memory, represent one of the most frequent features in the elderly. However, a great variability exists among aged subjects. Clinical reports and experimental data in animal models of ageing have shown that age-associated memory deficits are broadly identical to those induced by damage to the hippocampus. It is therefore not surprising that many functional properties of hippocampal neuronal networks are particularly altered with ageing. Whereas passive membrane properties of neurons are conserved with age, neuronal excitability is altered, in keeping with weaker performances of aged subjects in memory tasks. Synaptic transmission within hippocampal networks also decreases in brain ageing. Deficits concern both glutamatergic and cholinergic pathways, which represent the main excitatory neurotransmitter systems responsible for neuronal communication in the hippocampus. In addition, long-term changes in synaptic transmission, possible cellular substrates for learning and memory, are also impaired in ageing in correlation with cognitive impairments. Neuronal properties and synaptic plasticity closely depend on ion exchanges between intra- and extracellular compartments. Changes in ion regulation during ageing may therefore participate in altering functional properties of neuronal networks. Calcium dysregulation has been extensively investigated in brain ageing but the role of magnesium has received less attention though ageing constitutes a risk factor for magnesium deficit. One of general properties of magnesium at presynaptic fibre terminals is to reduce transmitter release. At the postsynaptic level, it closely controls the activation of the N-methyl-D-aspartate receptor, a subtype of glutamate receptor, which is critical for the expression of long-term changes in synaptic transmission. In addition, magnesium is a cofactor of many enzymes localized either in neurons or in glial cells that control neuronal properties and synaptic plasticity such as protein-kinase C, calcium/calmodulin-dependent protein kinase II and serine racemase. It is therefore likely that a change in magnesium concentration would significantly impair synaptic functions in the aged hippocampus. Experiments addressing this question remain too scarce but recent data indicate that magnesium is involved in age-related deficits in transmitter release, neuronal excitability and in some forms of synaptic plasticity such as long-term depression of synaptic transmission. Further studies are still necessary to better delineate to what extent magnesium contributes to the impaired cellular mechanisms of cognitive functions in the elderly which will help to develop new strategies to minimize age-related memory declines.

Magnesium and muscle performance in older persons: the InCHIANTI study1–3

The role of magnesium in maintaining muscle integrity and function in older adults is largely unknown. We aimed to investigate the relation between serum magnesium concentrations and muscle performance in older subjects. Data are from the baseline examination conducted between September 1998 and March 2000 of the InCHIANTI (aging in the Chianti area) study, a prospective epidemiologic survey of risk factors for late-life disability. From among 1453 randomly selected community residents completing a home interview, 1138 men (46%) and women (aged 66.7 +/- 15.2 y; x +/- SD) with complete data on muscle performance and serum magnesium who were not severely cognitively compromised and had no evidence of kidney disease or hypercalcemia were included in the analysis. Muscle performance was evaluated by grip strength, lower-leg muscle power, knee extension torque, and ankle extension isometric strength and was normalized for age and body mass index (BMI) within each sex. After adjustment for age, sex, BMI, laboratory variables, presence of chronic diseases, muscle area, muscle density, and physical activity level, serum magnesium concentrations were significantly associated with indexes of muscle performance, including grip strength (beta = 2.0 +/- 0.5, P = 0.0002), lower-leg muscle power (beta = 8.8 +/- 2.7, P = 0.001), knee extension torque (beta = 31.2 +/- 7.9, P < 0.0001), and ankle extension strength (beta = 3.8 +/- 0.5, P < 0.0001). The serum magnesium concentration is an independent correlate of muscle performance in older persons. Whether magnesium supplementation improves muscle function remains to be shown.

Magnesium and neoplasia: From carcinogenesis to tumor growth and progression or treatment

Magnesium is involved in a wide range of biochemical reactions that are crucial to cell proliferation, differentiation, angiogenesis, and apoptosis. Changes in magnesium availability have been shown to influence biological responses of immuno-inflammatory cells. Equally plausible seems to be an involvement of magnesium in the multistep and interconnected processes that lead to tumor formation and development; however, the “how” and “when” of such an involvement remain to be defined. Here, we reviewed in vitro and in vivo data that indicated a role for magnesium in many biological and clinical aspects of cancer (from neoplastic transformation to tumor growth and progression or pharmacologic treatment). In adopting this approach we went through a full circle from molecular aspects to observational or epidemiological studies that could reconcile in a unifying picture the otherwise fragmentary or puzzling data currently available on the role of magnesium in cancer.