Development of Cellular Magnesium Nano-Analysis in Treatment of Clinical Magnesium Deficiency

Magnesium: Biochemistry, Nutrition, Detection, and Social Impact of Diseases Linked to Its Deficiency

Magnesium plays an important role in many physiological functions. Habitually low intakes of magnesium and in general the deficiency of this micronutrient induce changes in biochemical pathways that can increase the risk of illness and, in particular, chronic degenerative diseases. The assessment of magnesium status is consequently of great importance, however, its evaluation is difficult. The measurement of serum magnesium concentration is the most commonly used and readily available method for assessing magnesium status, even if serum levels have no reliable correlation with total body magnesium levels or concentrations in specific tissues. Therefore, this review offers an overview of recent insights into magnesium from multiple perspectives. Starting from a biochemical point of view, it aims at highlighting the risk due to insufficient uptake (frequently due to the low content of magnesium in the modern western diet), at suggesting strategies to reach the recommended dietary reference values, and at focusing on the importance of detecting physiological or pathological levels of magnesium in various body districts, in order to counteract the social impact of diseases linked to magnesium deficiency.

Hypomagnesemia in diabetes patients: comparison of serum and intracellular measurement of responses to magnesium supplementation and its role in inflammation

PURPOSE

In this clinical trial, we assessed the efficacy of magnesium (Mg) supplementation in hypomagnesemic type 2 diabetes patients in restoring serum and intracellular Mg levels. The study had two coprimary end points: the change in serum and intracellular Mg level between baseline and after 3 months of supplementation. We compared the efficacy with regard to lowering hemoglobin A1c (HbA1c), C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and 8-isoprostane as secondary end points.

PATIENTS AND METHODS

In an open-label trial, 47 hypomagnesemic type 2 diabetes patients were administered 336 mg Mg daily. At baseline and after 3 months, serum, cellular Mg, and inflammation biomarkers were measured. For intracellular Mg levels, sublingual epithelial cells were analyzed by analytical scanning electron microscopy using computerized elemental X-ray analysis. Blood samples were analyzed for Mg, creatinine, HbA1c, and CRP. Systemic inflammatory markers including TNF-α and the oxidative stress marker 8-isoprostane were determined using enzyme-linked immunosorbent assay.

RESULTS

Mg supplementation significantly increased the intracellular and serum levels. Statistically clinical improvement in HbA1c and CRP levels was not observed, but significant decreases in TNF-α as well as in 8-isoprostane were found.

CONCLUSION

A feasible clinical method for the assessment of intracellular Mg was demonstrated in tissue samples obtained noninvasively, providing evidence for potential clinical translation of this method to routinely determine intracellular Mg concentration.

Oral Magnesium Supplementation in Chronic Kidney Disease Stages 3 and 4: Efficacy, Safety, and Effect on Serum Calcification Propensity-A Prospective Randomized Double-Blinded Placebo-Controlled Clinical Trial

Introduction

Chronic kidney disease (CKD) is associated with high cardiovascular morbidity and mortality. Recent evidence suggests that increases in both serum and intracellular magnesium (Mg) can slow or even prevent the development of vascular calcification seen in CKD. Serum calcification propensity (T₅₀) is a novel functional test, which is associated with all-cause mortality in CKD and measures the ability of serum to delay the formation of crystalline nanoparticles. Theoretically, increasing serum Mg should improve T₅₀ and thereby reduce the propensity towards ectopic calcification.

Methods

We conducted a randomized placebo-controlled double-blinded clinical trial to investigate the safety of 2 different doses of oral Mg supplementation in subjects with CKD stages 3 and 4 as well as their effects on intracellular Mg and T₅₀. Thirty-six subjects with CKD stages 3 and 4 were randomized to one of 3 groups (placebo, elemental Mg 15 mmol/d or elemental Mg 30 mmol/d) given as slow-release Mg hydroxide and followed for 8 weeks.

Results

Thirty-four subjects completed the trial. Intracellular Mg remained stable throughout the trial despite significant increases in both serum and urine Mg. T₅₀ increased significantly by 40 min from 256 ± 60 (mean ± SD) to 296 ± 64 minutes (95% confidence interval, 11-70, P < 0.05) in the Mg 30 mmol/d group after 8 weeks. No serious adverse events related to the study medication were reported during the study.

Discussion

Oral Mg supplementation was safe and well tolerated in CKD stages 3 and 4 and improved T₅₀, but did not increase intracellular Mg. Further studies are needed to investigate the long-term effects of Mg supplementation in CKD stage 3 and 4 and whether improvement in calcification propensity is related to clinical endpoints.

Magnesium and Space Flight

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.

Ketamine, magnesium and major depression--from pharmacology to pathophysiology and back

The glutamatergic mechanism of antidepressant treatments is now in the center of research to overcome the limitations of monoamine-based approaches. There are several unresolved issues. For the action of the model compound, ketamine, NMDA-receptor block, AMPA-receptor activation and BDNF release appear to be involved in a mechanism, which leads to synaptic sprouting and strengthened synaptic connections. The link to the pathophysiology of depression is not clear. An overlooked connection is the role of magnesium, which acts as physiological NMDA-receptor antagonist: 1. There is overlap between the actions of ketamine with that of high doses of magnesium in animal models, finally leading to synaptic sprouting. 2. Magnesium and ketamine lead to synaptic strengthening, as measured by an increase in slow wave sleep in humans. 3. Pathophysiological mechanisms, which have been identified as risk factors for depression, lead to a reduction of (intracellular) magnesium. These are neuroendocrine changes (increased cortisol and aldosterone) and diabetes mellitus as well as Mg(2+) deficiency. 4. Patients with therapy refractory depression appear to have lower CNS Mg(2+) levels in comparison to health controls. 5. Experimental Mg(2+) depletion leads to depression- and anxiety like behavior in animal models. 6. Ketamine, directly or indirectly via non-NMDA glutamate receptor activation, acts to increase brain Mg(2+) levels. Similar effects have been observed with other classes of antidepressants. 7. Depressed patients with low Mg(2+) levels tend to be therapy refractory. Accordingly, administration of Mg(2+) either alone or in combination with standard antidepressants acts synergistically on depression like behavior in animal models.

CONCLUSION

On the basis of the potential pathophysiological role of Mg(2+)-regulation, it may be possible to predict the action of ketamine and of related compounds based on Mg(2+) levels. Furthermore, screening for compounds to increase neuronal Mg(2+) concentration could be a promising instrument to identify new classes of antidepressants. Overall, any discussion of the glutamatergic system in affective disorders should consider the role of Mg(2+).

Hypomagnesemia and inflammation: clinical and basic aspects

In recent years, increasing awareness of hypomagnesemia has resulted in clinical trials that associate this mineral deficiency with diabetes, metabolic syndrome, and drug therapies for cancer and cardiovascular diseases. However, diagnostic testing for tissue deficiency of magnesium still presents a challenge. Investigations of animal and cellular responses to magnesium deficiency have found evidence of complex proinflammatory pathways that may lead to greater understanding of mediators of the pathobiology in neuronal, cardiovascular, intestinal, renal, and hematological tissues. The roles of free radicals, cytokines, neuropeptides, endotoxin, endogenous antioxidants, and vascular permeability, and interventions to limit the inflammatory response associated with these parameters, are outlined in basic studies of magnesium deficiency. It is hoped that this limited review of inflammation associated with some diseases complicated by magnesium deficiency will prompt greater awareness by clinicians and other health providers and in turn increase efforts to prevent and treat this disorder.

Update on the assessment of magnesium status

Magnesium (Mg) is the fourth most abundant mineral in the body and the most abundant intracellular divalent cation, with essential roles in many physiological functions. Consequently, the assessment of Mg status is important for the study of diseases associated with chronic deficiency. In spite of intense research activities there is still no simple, rapid, and accurate laboratory test to determine total body Mg status in humans. However, serum Mg < 0.75 mmol/l is a useful measurement for severe deficiency, and for values between 0.75 and 0.85 mmol/l a loading test can identify deficient subjects. The loading test seems to be the gold standard for Mg status, but is unsuitable in patients with disturbed kidney and intestinal functions when administered orally. There is also a need to reach a consensus on a standardized protocol in order to compare results obtained in different clinical units. Other cellular Mg measurements, such as total or ionized Mg, frequently disagree and more research and systematic evaluations are needed. Muscle Mg appears to be a good marker, but biopsies limit its usefulness, as is the case with bone Mg, the most important but heterogeneous Mg compartment. The development of new and non invasive techniques such as nuclear magnetic resonance (NMR) may provide valuable tools for routinely analysing ionized Mg in tissues. With the development of molecular genetics techniques, the recent discovery of Transient Receptor Potential Melastatin channels offers new possibilities for the sensitive and rapid evaluation of Mg status in humans.

The nerve-heart connection in the pro-oxidant response to Mg-deficiency

Magnesium is a micronutrient essential for the normal functioning of the cardiovascular system, and Mg deficiency (MgD) is frequently associated in the clinical setting with chronic pathologies such as CHF, diabetes, hypertension, and other pathologies. Animal models of MgD have demonstrated a systemic pro-inflammatory/pro-oxidant state, involving multiple tissues/organs including neuronal, hematopoietic, cardiovascular, and gastrointestinal systems; during later stages of MgD, a cardiomyopathy develops which may result from a cascade of inflammatory events. In rodent models of dietary MgD, a significant rise in circulating levels of proinflammatory neuropeptides such as substance P (SP) and calcitonin gene-related peptide among others, was observed within days (1-7) of initiating the Mg-restricted diet, and implicated a neurogenic trigger for the subsequent inflammatory events; this early "neurogenic inflammation" phase may be mediated in part, by the Mg-gated N: -methyl-D-aspartate (NMDA) receptor/channel complex. Deregulation of the NMDA receptor may trigger the abrupt release of neuronal SP from the sensory-motor C-fibers to promote the subsequent pro-inflammatory changes: elevations in circulating inflammatory cells, inflammatory cytokines, histamine, and PGE(2) levels, as well as formation of nitric oxide, reactive oxygen species, lipid peroxidation products, and depletion of key endogenous antioxidants. Concurrent elevations of tissue CD14, a high affinity receptor for lipopolyssacharide, suggest that intestinal permeability may be compromised leading to endotoxemia. If exposure to these early (1-3 weeks MgD) inflammatory/pro-oxidant events becomes prolonged, this might lead to impaired cardiac function, and when co-existing with other pathologies, may enhance the risk of developing chronic heart failure.