Human Placental-Specific Epipolymorphism and its Association with Adverse Pregnancy Outcomes

Interindividual variation in DNA-methylation level is widespread in the human genome, despite its critical role in regulating gene expression. The nature of this variation, including its tissue-specific nature, and the role it may play in human phenotypic variation and disease is still poorly characterized. The placenta plays a critical role in regulating fetal growth and development in ways that have lifelong effects on health. To identify genes with a high degree of interindividual DNA methylation variation in the human placenta, we surveyed the human genome using the Illumina GoldenGate Methylation Cancer panel targeting 1505 CpG sites of 807 genes. While many sites show a continuous pattern of methylation levels, WNT2, TUSC3 and EPHB4 were identified to have a polymorphic “on-or-off” pattern of DNA methylation variation at their promoter region which was confirmed by pyrosequencing. Methylation of these genes can be found in 7%–25% of over 100 placentas tested. The methylation state at the promoter of these genes is concordant with mRNA allelic expression. In three informative cases TUSC3 was observed to be methylated on the maternal allele, and it is thus possible this represents a polymorphically imprinted gene. Furthermore, TUSC3 promoter methylation showed evidence for association with preeclampsia. A biological significance of these methylation allelic polymorphisms (MAPs) to human placental diversity is further implied by their placental specificity and absence in mouse. An extended study of blood suggests that MAPs may also be found in other tissues, implicating their utility for tissue-specific association with complex disorders. The identification of such “epipolymorphism” in other tissues and their use in association studies, should improve our understanding of interindividual phenotypic variability and complex disease susceptibility

Newly Developed Mg2+–Selective Fluorescent Probe Enables Visualization of Mg2+ Dynamics in Mitochondria

Mg2+ plays important roles in numerous cellular functions. Mitochondria take part in intracellular Mg2+ regulation and the Mg2+ concentration in mitochondria affects the synthesis of ATP. However, there are few methods to observe Mg2+ in mitochondria in intact cells. Here, we have developed a novel Mg2+–selective fluorescent probe, KMG-301, that is functional in mitochondria. This probe changes its fluorescence properties solely depending on the Mg2+ concentration in mitochondria under physiologically normal conditions. Simultaneous measurements using this probe together with a probe for cytosolic Mg2+, KMG-104, enabled us to compare the dynamics of Mg2+ in the cytosol and in mitochondria. With this method, carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP)–induced Mg2+ mobilization from mitochondria to the cytosol was visualized. Although a FCCP–induced decrease in the Mg2+ concentration in mitochondria and an increase in the cytosol were observed both in differentiated PC12 cells and in hippocampal neurons, the time-courses of concentration changes varied with cell type. Moreover, the relationship between mitochondrial Mg2+ and Parkinson's disease was analyzed in a cellular model of Parkinson's disease by using the 1-methyl-4-phenylpyridinium ion (MPP+). A gradual decrease in the Mg2+ concentration in mitochondria was observed in response to MPP+ in differentiated PC12 cells. These results indicate that KMG-301 is useful for investigating Mg2+ dynamics in mitochondria. All animal procedures to obtain neurons from Wistar rats were approved by the ethical committee of Keio University (permit number is 09106-(1))

Magnesium transport in hypertension

Epidemiological, clinical and experimental evidence indicates an inverse association between Mg<sup>2+</sup> levels (serum and tissue) and blood pressure. Magnesium may influence blood pressure by modulating vascular tone and structure through its effects on numerous biochemical reactions that control vascular contraction/dilation, growth/apoptosis, differentiation and inflammation. Magnesium acts as a calcium channel antagonist, it stimulates production of vasodilator prostacyclins and nitric oxide and it alters vascular responses to vasoactive agonists. Mammalian cells regulate Mg<sup>2+</sup> concentration through specialized influx and efflux transport systems that have only recently been characterized. Magnesium efflux occurs via Na<sup>2+</sup>-dependent and Na<sup>2+</sup>-independent pathways. Mg<sup>2+</sup> influx is controlled by recently cloned transporters including Mrs2p, SLC41A1, SLC41A1, ACDP2, MagT1, TRPM6 and TRPM7. Alterations in some of these systems may contribute to hypomagnesemia and intracellular Mg<sup>2+</sup> deficiency in hypertension. In particular increased Mg<sup>2+</sup> efflux through altered regulation of the vascular Na<sup>2+</sup>/Mg<sup>2+</sup> exchanger and decreased Mg<sup>2+</sup> influx due to defective vascular and renal TRPM6/7 expression/activity may be important. This review discusses the role of Mg<sup>2+</sup> in vascular biology and implications in hypertension and focuses on the putative transport systems that control vascular magnesium homeostasis. Much research is still needed to clarify the exact mechanisms of Mg<sup>2+</sup> regulation in the cardiovascular system and the implications of aberrant transcellular Mg<sup>2+</sup> transport in the pathogenesis of cardiovascular disease

Role of magnesium in hypertension

Magnesium affects blood pressure by modulating vascular tone and reactivity. It acts as a calcium channel antagonist, it stimulates production of vasodilator prostacyclins and nitric oxide and it alters vascular responses to vasoactive agonists. Magnesium deficiency has been implicated in the pathogenesis of hypertension with epidemiological and experimental studies demonstrating an inverse correlation between blood pressure and serum magnesium levels. Magnesium also influences glucose and insulin homeostasis, and hypomagnesemia is associated with metabolic syndrome.Although most epidemiological and experimental studies support a role for low magnesium in the pathophysiology of hypertension, data from clinical studies have been less convincing. Furthermore, the therapeutic value of magnesium in the management of hypertension is unclear. The present review addresses the role of magnesium in the regulation of vascular function and blood pressure and discusses the implications of magnesium deficiency in experimental and clinical hypertension, in metabolic syndrome and in pre-eclampsia

Downregulation of renal TRPM7 and increased inflammation and fibrosis in aldosterone-infused mice: effects of magnesium

Hyperaldosteronism is associated with hypertension, cardiovascular fibrosis, and electrolyte disturbances, including hypomagnesemia. Mechanisms underlying aldosterone-mediated Mg2+ changes are unclear, but the novel Mg2+ transporters TRPM6 and TRPM7 may be important. We examined whether aldosterone influences renal TRPM6/7 and the TRPM7 downstream target annexin-1 and tested the hypothesis that Mg2+ administration ameliorates aldosterone-induced cardiovascular and renal injury and prevents aldosterone-associated hypertension. C57B6 mice were studied (12 weeks, n=8 to 9/group); (1) control group (0.2% dietary Mg2+), (2) Mg2+ group (0.75% dietary Mg2+), (3) aldosterone group (Aldo, 400 μg/kg/min and 0.9% NaCl drinking water), and (4) Aldo+Mg2+ group. Blood pressure was unaltered by aldosterone and was similar in all groups throughout the experiment. Serum Na+ was increased and serum K+ and Mg2+ decreased in the Aldo group. Aldo mice had hypomagnesuria and proteinuria, and renal, cardiac, and aortic fibrosis, which were normalized by Mg2+ supplementation. Renal and cardiovascular expression of interleukin-6, VCAM1 and COX2 was increased in the Aldo group. Magnesium attenuated renal and cardiac interleukin-6 content and decreased renal VCAM1 and cardiac COX2 expression (P<0.05). Aldosterone decreased expression of renal TRPM7 and the downstream target annexin-1 (P<0.05) without effect on TRPM6. Whereas Mg2+ increased mRNA expression of TRPM6 and TRPM7, it had no effect on TRPM7 and annexin-1 protein content. Our data demonstrate that aldosterone mediates blood pressure–independent renal and cardiovascular fibrosis and inflammation through Mg2+-sensitive pathways. We suggest that altered Mg2+ metabolism in hyperaldosteronism may relate to TRPM7 downregulation and that Mg2+ protects against cardiovascular and renal damaging actions of aldosterone

Mechanical Properties and Microstructure of a Metakaolin-Based Inorganic Polymer Mortar Reinforced with Quartz Sand

The synthesis, mechanical behaviour, and microstructure of metakaolin-based geopolymer mortar reinforced with quartz sand are presented in this investigation. Fine sand (quartz sand) aggregate were added in different proportions of 50, 60, 70 or 80 wt.% to prepare the fresh metakaolin-based geopolymer paste. The geopolymer mortar was achieved by a mixture of geopolymer paste and river sand in the ratio 2:5 by mass. The mixture of sodium hydroxide solution (10 M) and sodium silicate solution (Na2SiO3) in a volume ratio of 2:3 was used as an alkaline activator. All the specimens were cured at room temperature and tested after 28 days of curing. The investigations on microstructure and physical properties indicated a significant reduction of the open pores and interconnection of micro and meso cracks in the structure network with increase in the amount of quartz sand. As a consequence, the samples show a good mechanical strength principally with the addition of 60 wt.% of quartz sand to binder with values of 8 and 66 MPa for flexural strength and compressive strength, respectively

Changes in intestinal bifidobacteria levels are associated with the inflammatory response in magnesium-deficient mice

Magnesium (Mg) deficiency is a common nutritional disorder that is linked to an inflammatory state characterized by increased plasma acute phase protein and proinflammatory cytokine concentrations. Recent studies have shown that changes in the composition of gut microbiota composition participate in systemic inflammation. In this study, therefore, we assessed the potential role of gut microbiota in intestinal and systemic inflammation associated with Mg deficiency in mice. For this purpose, mice were fed a control or Mg-deficient diet (500 mg vs. 70 mg Mg/kg) for 4 or 21 d. Compared with the mice fed the control diet, mice fed the Mg-deficient diet for 4 d had a lower gut bifidobacteria content (-1.5 log), a 36-50% lower mRNA content of factors controlling gut barrier function in the ileum (zonula occludens-1, occludin, proglucagon), and a higher mRNA content (by similar to 2-fold) in the liver and/or intestine of tumor necrosis factor-alpha, interleukin-6, CCAAT/enhancer binding protein homologous protein, and activating transcription factor 4, reflecting inflammatory and cellular stress. In contrast, mice fed the Mg-deficient diet for 21 d had a higher cecal bifidobacteria content compared with the control group, a phenomenon accompanied by restoration of the intestinal barrier and the absence of inflammation. In conclusion, we show that Mg deficiency, independently of any other changes in nutrient intake, modulates the concentration of bifidobacteria in the gut, a phenomenon that may time-dependently affect inflammation and metabolic disorders in mice. J. Nutr. 140: 509-514, 2010