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Magnesium and calcium ions: roles in bacterial cell attachment and biofilm structure maturation.
Wang, T, Flint, S, Palmer, J
Biofouling. 2019;(9):959-974
Abstract
The ubiquitous divalent cations magnesium and calcium are important nutrients required by bacteria for growth and cell maintenance. Multi-faceted roles are shown both in bacterial initial attachment and biofilm maturation. The effects of calcium and magnesium can be highlighted in physio-chemical interactions, gene regulation and bio-macromolecular structural modification, which lead to either promotion or inhibition of biofilms. This review outlines recent research addressing phenotypic changes and mechanisms undertaken by calcium and magnesium in affecting bacterial biofilm formation.
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2.
The Problematic Use of Dietary Reference Intakes to Assess Magnesium Status and Clinical Importance.
Nielsen, FH
Biological trace element research. 2019;(1):52-59
Abstract
Determination of the public health concern about magnesium (Mg) in health and disease has been confounded by the lack of a practical measure of status. This has resulted in a lack of consistency in associating Mg deficiency with specific pathological conditions. Some attempts at associating Mg with a chronic disease have used the Dietary Reference Intakes (DRIs) as a status assessment measure. Use of current DRIs for Mg is problematic because recent evidence suggests that they should be updated and based on body weight. An evidence-based suggested Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) for a 70-kg individual is 175 and 250 mg/day, respectively. However, numerous dietary and physiological factors can affect the need for Mg and thus affect the use of the current or suggested new DRIs to assess Mg status. Calcium intakes above normal requirements can decrease Mg balance and exacerbate signs of Mg deficiency. Mg deficiency apparently occurs often in obesity because of increased need to counteract the inflammatory stress induced by adipose tissue dysfunction. Deficiency in anti-oxidant nutrients such as vitamin E and selenium can exacerbate a response to low dietary Mg indicated by increased oxidative stress which can lead to chronic disease. Dietary modifiers of Mg absorption and excretion affect balance and thus the need for Mg. Factors decreasing Mg balance include low dietary protein and non-fermentable fiber, while factors that can increase balance include fructose and fermentable fiber and fructose-containing oligosaccharides. Use of the DRIs to assess the Mg status of a population or group needs to consider their physiological characteristics and dietary habits and be aware that the DRIs may need updating. The DRIs only can be considered a component of a toolbox that presently includes serum Mg concentration and the daily urinary Mg excretion to assess the Mg status of an individual.
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3.
Current Structural Knowledge on the CNNM Family of Magnesium Transport Mediators.
Giménez-Mascarell, P, González-Recio, I, Fernández-Rodríguez, C, Oyenarte, I, Müller, D, Martínez-Chantar, ML, Martínez-Cruz, LA
International journal of molecular sciences. 2019;(5)
Abstract
The cyclin and cystathionine β-synthase (CBS) domain magnesium transport mediators, CNNMs, are key players in maintaining the homeostasis of magnesium in different organs. The human family includes four members, whose impaired activity causes diseases such as Jalili Syndrome or Familial Hypomagnesemia, but is also linked to neuropathologic disorders, altered blood pressure, and infertility. Recent findings demonstrated that CNNMs are associated with the highly oncogenic phosphatases of the regenerating liver to promote tumor growth and metastasis, which has attracted renewed focus on their potential exploitation as targets for cancer treatment. However, the exact function of CNNMs remains unclear and is subject to debate, proposed as either direct transporters, sensors, or homeostatic factors. This review gathers the current structural knowledge on the CNNM family, highlighting similarities and differences with the closely related structural partners such as the bacterial Mg2+/Co2+ efflux protein CorC and the Mg2+ channel MgtE.
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4.
Serum magnesium level and hematoma expansion in patients with intracerebral hemorrhage.
Jafari, M, Di Napoli, M, Lattanzi, S, Mayer, SA, Bachour, S, Bershad, EM, Damani, R, Datta, YH, Divani, AA
Journal of the neurological sciences. 2019;:39-44
Abstract
Spontaneous intracerebral hemorrhage (ICH) is a devastating subtype of stroke that results in significant rates of mortality and morbidities. The initial hematoma volume, hematoma expansion (HE), blood pressure (BP), and coagulopathy are considered strong predictors of clinical outcomes and mortality. Low serum magnesium (Mg++) levels have been shown to be associated with larger initial hematoma and greater HE. Coagulopathy, platelet dysfunction, high BP, and increased inflammatory response might form the mechanistic link between low serum Mg++ levels, larger hematoma size and greater HE. However, randomized clinical trials administering intravenous Mg++ have shown no benefit over placebo in ICH patients. The confounding effect of hypocalcemia and a delay in Mg++ trafficking across the blood-brain barrier might explain the futile results for intravenous Mg++ therapy. In the current review, we will discuss the evidence regarding the possible role of low serum Mg++ level on HE in acute ICH.
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5.
ATP, Mg2+, Nuclear Phase Separation, and Genome Accessibility.
Wright, RHG, Le Dily, F, Beato, M
Trends in biochemical sciences. 2019;(7):565-574
Abstract
Misregulation of the processes controlling eukaryotic gene expression can result in disease. Gene expression is influenced by the surrounding chromatin; hence the nuclear environment is also of vital importance. Recently, understanding of chromatin hierarchical folding has increased together with the discovery of membrane-less organelles which are distinct, dynamic liquid droplets that merge and expand within the nucleus. These 'sieve'-like regions may compartmentalize and separate functionally distinct regions of chromatin. This article aims to discuss recent studies on nuclear phase within the context of poly(ADP-ribose), ATP, and Mg2+ levels, and we propose a combinatorial complex role for these molecules in phase separation and genome regulation. We also discuss the implications of this process for gene regulation and discuss possible strategies to test this.
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6.
Magnesium matrix nanocomposites for orthopedic applications: A review from mechanical, corrosion, and biological perspectives.
Shahin, M, Munir, K, Wen, C, Li, Y
Acta biomaterialia. 2019;:1-19
Abstract
Magnesium (Mg) and some of its alloys have attracted extensive interests for biomedical applications as they exhibit biodegradability and low elastic modulus that is closer to natural bones than the currently used metallic implant materials such as titanium (Ti) and its alloys, stainless steels, and cobalt-chromium (Co-Cr) alloys. However, the rapid degradation of Mg alloys and loss of their mechanical integrity before sufficient bone healing impede their clinical application. Our literature review shows that magnesium matrix nanocomposites (MMNCs) reinforced with nanoparticles possess enhanced strength, high corrosion resistance, and good biocompatibility. This article provides a detailed analysis of the effects of nanoparticle reinforcements on the mechanical properties, corrosion behavior, and biocompatibility of MMNCs as promising biodegradable implant materials. The governing equations to quantitatively predict the mechanical properties and underlying synergistic strengthening mechanisms in MMNCs are elucidated. The potential, recent advances, challenges and future research directions in relation to nanoparticles reinforced MMNCs are highlighted. STATEMENT OF SIGNIFICANCE Critically reviewing magnesium metal matrix nanocomposites (MMNCs) for the biomedical application. Clear definitions of strengthening mechanisms using reinforcement particle in the magnesium matrix, as there were controversial in governing equations of strengthening parameters. Providing better understanding of the effect of particle size, volume fraction, interfacial bonding, and uniform dispersion of reinforcement particles on MMNCs.
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7.
Hypomagnesemia and hypermagnesemia.
Van Laecke, S
Acta clinica Belgica. 2019;(1):41-47
Abstract
Introduction:Magnesium is an essential element which also has pleiotropic effects in humans. Recent studies have altered our interpretation of a disturbed magnesium balance both leading to hypomagnesemia and hypermagnesemia. Methods: a narrative review of their clinical relevance is presented. Results: Although magnesium balance is strictly controlled by the kidneys, hypomagnesemia is fairly common, especially in people with comorbid conditions. Increased renal magnesium wasting, often aggravated by drugs, is commonly found in conditions associated with unfavorable outcomes such as diabetes mellitus and sepsis. Depending on its severity hypomagnesemia may reveal itself by potentially hazardous neurological and cardiovascular symptoms. Intravenous magnesium is an evidence-based treatment of torsades de pointes and preeclampsia irrespective of the presence of preexisting hypomagnesemia. Magnesium deficiency and/or hypomagnesemia has been linked to cardiovascular disease, vascular calcification and endothelial function both in vitro and in vivo. (Severe) hypermagnesemia can be life-threatening but is almost exclusively observed in patients with substantially decreased kidney function associated with high magnesium intake through supplements or magnesium containing cathartics or antacids. Conclusion:It remains unclear whether mild hypermagnesemia confers survival benefit especially in subjects with decreased kidney function. The role of oral magnesium supplementation of chronic mild asymptomatic hypomagnesemia also merits further exploration through interventional studies in various study populations.
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8.
Proton pump inhibitor-induced hypomagnesemia complicated with serious cardiac arrhythmias.
Chrysant, SG
Expert review of cardiovascular therapy. 2019;(5):345-351
Abstract
Introduction: Magnesium is the third most common intracellular ion after potassium and calcium and is an important element in the functions of the body, since it participates in more than 300 enzyme systems. It also, plays a significant role in the transport of calcium and potassium across the cell membranes and protects against cardiac arrhythmias and is useful for their treatment due to hypomagnesemia induced from the proton pump inhibitors (PPIs). Areas covered: PPIs are used for the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD), but have been associated with hypomagnesemia with serious cardiac arrhythmias including torsades de pointes (TdP). To better understand the magnitude of this problem, a Medline search of the English language literature was conducted from 2010 to 2018 and 35 papers with pertinent information were selected. Expert commentary: The review of these papers suggests that PPIs cause hypomagnesemia, which could be associated with serious cardiac arrhythmias including TdP. However, its incidence is not very common considering the millions of people taking PPIs, but the FDA has advised the physicians to be watchful about this serious adverse effect of PPIs and check the magnesium levels before initiation of PPI treatment.
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9.
Mg2+ homeostasis and transport in cyanobacteria - at the crossroads of bacterial and chloroplast Mg2+ import.
Pohland, AC, Schneider, D
Biological chemistry. 2019;(10):1289-1301
Abstract
Magnesium cation (Mg2+) is the most abundant divalent cation in living cells, where it is required for various intracellular functions. In chloroplasts and cyanobacteria, established photosynthetic model systems, Mg2+ is the central ion in chlorophylls, and Mg2+ flux across the thylakoid membrane is required for counterbalancing the light-induced generation of a ΔpH across the thylakoid membrane. Yet, not much is known about Mg2+ homoeostasis, transport and distribution within cyanobacteria. However, Mg2+ transport across membranes has been studied in non-photosynthetic bacteria, and first observations and findings are reported for chloroplasts. Cyanobacterial cytoplasmic membranes appear to contain the well-characterized Mg2+ channels CorA and/or MgtE, which both facilitate transmembrane Mg2+ flux down the electrochemical gradient. Both Mg2+ channels are typical for non-photosynthetic bacteria. Furthermore, Mg2+ transporters of the MgtA/B family are also present in the cytoplasmic membrane to mediate active Mg2+ import into the bacterial cell. While the cytoplasmic membrane of cyanobacteria resembles a 'classical' bacterial membrane, essentially nothing is known about Mg2+ channels and/or transporters in thylakoid membranes of cyanobacteria or chloroplasts. As discussed here, at least one Mg2+ channelling protein must be localized within thylakoid membranes. Thus, either one of the 'typical' bacterial Mg2+ channels has a dual localization in the cytoplasmic plus the thylakoid membrane, or another, yet unidentified channel is present in cyanobacterial thylakoid membranes.
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10.
Magnesium and calciprotein particles in vascular calcification: the good cop and the bad cop.
Zeper, LW, de Baaij, JHF
Current opinion in nephrology and hypertension. 2019;(4):368-374
Abstract
PURPOSE OF REVIEW Vascular calcification is a major contributor to increased cardiovascular mortality in chronic kidney disease (CKD). Recently, calciprotein particles (CPP) were identified to drive the calcification process. CPP may explain the effects of high phosphate on vascular calcification. Magnesium is a promising novel therapeutic approach to halt vascular calcification, because it inhibits CPP maturation and is associated with reduced cardiovascular mortality in CKD. We aim to examine the current evidence for the role of CPP in the calcification process and to explain how magnesium prevents calcification. RECENT FINDINGS A recent meta-analysis concluded that reducing high phosphate levels in CKD patients does not associate with lowering cardiovascular mortality. Inhibition of CPP formation prevents phosphate-induced calcification in vitro. Consequently, delaying CPP formation and maturation may be a clinical approach to reduce calcification. Magnesium inhibits CPP maturation and vascular calcification. Clinical pilot studies suggest that magnesium is a promising intervention strategy against calcification in CKD patients. SUMMARY CPP induce vascular calcification and are modulated by serum phosphate and magnesium concentrations. Magnesium is a strong inhibitor of CPP maturation and therefore, a promising therapeutic approach to reduce vascular calcification in CKD. Currently, several studies are being performed to determine the clinical outcomes of magnesium supplementation in CKD.