Magnesium status, serum HDL cholesterol, and apolipoprotein A-1 levels

Heavy metals controlling cardiovascular diseases risk factors in myocardial infarction patients in critically environmentally heavy metal-polluted steel industrial town Mandi-Gobindgarh (India)

Heavy metals (HMs) have a very significant clinical role in the pathogenesis, progression and management of cardiovascular diseases (CVDs). The prevalence of CVDs was reported to be higher in critically environmentally HM-polluted (EHMP) steel industrial town Mandi-Gobindgarh (India) for the last more than a decade. To ascertain the role of HMs in the onset of CVDs, the present study was chosen to investigate HMs content in myocardial infarction (MI) patients from EHMP steel industrial town Mandi-Gobindgarh. Total of 110 MI patients along with number- and age-matched healthy volunteers were recruited in the present investigation. The CVDs risk factors estimated in MI patients were overweight (higher body mass index), hypertension (higher systolic and diastolic blood pressures), dyslipidaemia (higher serum cholesterol, triglycerides and lower HDL cholesterol), inflammation (higher-serum C reactive protein and aldosterone) and elevated oxidative stress (higher urinary 8-hydroxydeoxyguanosine). An imbalance of serum electrolyte concentrations including Na (hypernatremia), Ca (hypercalcaemia) and K (hypokalaemia) was also observed in MI patients in which CVDs risk factors were found to correlate positively with serum Na and Ca and negatively with serum K, respectively. Hair HM analysis was used as a bio-indicator for monitoring body HM status from past environmental HM exposure in which CVDs risk factors were observed to correlate positively with higher hair concentrations of Zn, Fe, Mo, Pb, As, Ca and Na and negatively with lower hair concentrations of Cu, Mg, Mn and K in MI patients, respectively. Thus, higher hair concentrations of Zn and Pb indicate their higher environmental exposure and possible cause of higher CVDs risk factors in MI patients from Mandi-Gobindgarh.

Associations of Serum Calcium, Magnesium Levels, and Their Ratio with Apolipoproteins in Chinese Adults with Coronary Artery Disease: a Cross-Sectional Study

Former evidence regarding the associations of serum calcium (Ca) and magnesium (Mg) levels with apolipoproteins (Apos) in Chinese adults with coronary artery disease (CAD) were scarce. A total of 6781 patients with CAD were included in this cross-sectional study; mean age was 61.0 years. The associations of serum Ca, Mg, and Ca/Mg ratio with Apos (e.g., ApoA1, ApoB, and ApoB/A1 ratio) were determined using multivariate analysis of covariance. Serum Ca, Mg, and Ca/Mg ratio tended to have positive associations with ApoA1, while negative associations of serum Ca, Mg, and Ca/Mg ratio with ApoB and ApoB/A1 ratio were detected. In multivariate analysis, serum Ca, Mg, and Ca/Mg ratio were positively associated with ApoA1 levels (Q [quintile] 5 vs. Q1: 1.245 vs. 1.151 g/L for Ca, 1.207 vs. 1.188 g/L for Mg, 1.202 vs. 1.171 g/L for Ca/Mg ratio). In contrast, negative associations of serum Mg and Ca/Mg ratio with ApoB and ApoB/A1 ratio were shown. The corresponding ApoB and ApoB/A1 ratio values were 0.856 (vs. 0.887 g/L) and 0.728 (vs. 0.771) for Mg, and 0.814 (vs. 0.854 g/L) and 0.695 (vs. 0.751) for Ca/Mg ratio in Q5 compared with Q1. Serum Ca was inversely associated with ApoB and ApoB/A1 ratio (Q5 vs. Q4: 0.804 vs. 0.847 g/L for ApoB; Q5 vs. Q1: 0.662 vs. 0.732 for ApoB/A1 ratio). Path analysis showed that mediating effects of BMI on the "Ca or Mg-Apos" associations were not found. In summary, serum Ca and Mg tended to have positive associations with ApoA1 levels in patients with CAD, but had inverse associations with ApoB levels and ApoB/A1 ratio. Serum Ca/Mg ratio may be a more precise marker than serum Mg or serum Ca measures alone in assessing Apos measures of CAD risk.

Salts and energy balance: A special role for dietary salts in metabolic syndrome

BACKGROUND

Dietary salts sodium (Na⁺), potassium (K⁺), magnesium (Mg2⁺), and calcium (Ca2⁺) are important in metabolic diseases. Yet, we do not have sufficient understanding on the salts global molecular network in these diseases. In this systematic review we have pooled information to identify the general effect of salts on obesity, insulin resistance and hypertension.

AIMS

To assess the roles of salts in metabolic disorders by focusing on their individual effect and the network effect among these salts.

METHODS

We searched articles in PubMed, EMBASE and Google Scholar. We selected original laboratory research, systematic reviews, clinical trials, observational studies and epidemiological data that focused on dietary salts and followed the preferred reporting items for systematic review in designing the present systematic review.

RESULTS

From the initial search of 2898 studies we selected a total of 199 articles that met our inclusion criteria and data extraction. Alterations in metabolic pathways associated with the sensitivity of sodium, potassium, magnesium and calcium may lead to obesity, hypertension, and insulin resistance. We found that the results of most laboratory research, animal studies and clinical trials are coherent but some research outcome are either inconsistent or inconclusive.

CONCLUSION

Important of salts in metabolic disorder is evident. In order to assess the effects of dietary salts in metablic diseases, environmental factors, dietary habits, physical activity, and the microbiome, should be considered in any study. Although interest in this area of research continues to grow, the challenge is to integrate the action of these salts in metabolic syndrom.

Defective lipid metabolism associated with mutation in klf-2 and klf-3: important roles of essential dietary salts in fat storage

Background

Dietary salts are important factors in metabolic disorders. They are vital components of enzymes, vitamins, hormones, and signal transduction that act synergistically to regulate lipid metabolism. Our previous studies have identified that Krüppel-like factor −3 (KLF-3) is an essential regulator of lipid metabolism. However, it is not known if KLF-2 also regulates lipid metabolism and whether KLF-2 and −3 mediate the effects of dietary salts on lipid metabolism.

Methods

In this study, we used klf mutants [homozygous klf-2 (ok1043) V and klf-3 (ok1975) II mutants] to investigate the role of dietary salts in lipid metabolism. All gene expression was quantified by qRT-PCR. Localization of KLF-2 was analyzed by the expression of klf-2::gfp (in pPD95.75 vector) using a fluorescent microscope. Fat storage was measured by Oil Red O staining.

Results

Klf-2 was identified to express in the intestine during all stages of Caenorhabditis elegans development with peak expression at L3 stage. Mutation of klf-2 increased fat accumulation. Under regular growth media free of Ca^2+, the expression of both klf-2 and −3 was inhibited slightly; further their expression reduced significantly in WT worms fed on 10X Ca²⁺ diet. When klf-3 was mutated, the expression of klf-2 increased under 10X Ca²⁺ diet; but when klf-2 was mutated, the expression of klf-3 was not altered under 10X Ca²⁺ diet. Overall, Mg²⁺ and K⁺ were less effective on the gene expression of klfs. KLF target gene Ce-C/EBP-2 showed elevated expression in WT and klf-3 (ok1975) worms with changed Ca²⁺ concentrations but not in klf-2 (ok1043) worms. However, high Ca⁺² diet exhibited inhibitory effect on Ce-SREBP expression in WT worms.

Conclusion

Dietary Ca²⁺ is most effective on fat storage and klf-2 expression, wherein high Ca²⁺ diet decreased klf-2 expression and reduced fat buildup. Mechanistic study identified Ce-C/EBP (C48E7.3; lpd-2) and Ce-SREBP (Y47D3B.7; lpd-1) as the target genes of klf-2 and/or klf-3 to mediate lipid metabolism. This study identifies a new function of klf-2 in inhibiting fat buildup and reveals the interplay between dietary salts and klf-2 and klf-3 in lipid metabolism.

Association of hypermagnesemia and blood pressure in the critically ill

BACKGROUND

Although magnesium is important in the biology of blood pressure regulation, little clinical data exist on the association of hypermagnesemia and blood pressure.

METHOD

We examined the association of hypermagnesemia and SBP in a cross-sectional study of 10 521 ICU patients from a single tertiary care medical center, 6% of whom had a serum magnesium above 2.6 mg/dl at time of admission.

RESULTS

In a multivariable analysis, hypermagnesemia was associated with SBP 6.2 mmHg lower [95% confidence interval (CI) -8.2, -4.2, P < 0.001] than in patients with admission values of serum magnesium 2.6 mg/dl or less. Each mg/dl increase in serum magnesium was associated with a decrease in SBP of 4.3 mmHg (95% CI -5.5, -3.1, P < 0.001). In addition, hypermagnesemic patients had a 2.48-fold greater likelihood (95% CI 2.06, 3.00, P < 0.001) of receiving intravenous vasopressors during the first 24 h of ICU care, independent of admission SBP.

CONCLUSION

Our findings add support to the biologic importance of magnesium regulation in blood pressure control.

Transient receptor potential melastatin 7 (TRPM7) cation channels, magnesium and the vascular system in hypertension

Decreased Mg(2+) concentration has been implicated in altered vascular reactivity, endothelial dysfunction and structural remodeling, processes important in vascular changes and target organ damage associated with hypertension. Unlike our knowledge of other major cations, mechanisms regulating cellular Mg(2+) handling are poorly understood. Until recently little was known about protein transporters controlling transmembrane Mg(2+) influx. However, new research has uncovered a number of genes and proteins identified as transmembrane Mg(2+) transporters, particularly transient receptor potential melastatin (TRPM) cation channels, TRPM6 and TRPM7. Whereas TRPM6 is found primarily in epithelial cells, TRPM7 is ubiquitously expressed. Vascular TRPM7 has been implicated as a signaling kinase involved in vascular smooth muscle cell growth, apoptosis, adhesion, contraction, cytoskeletal organization and migration, and is modulated by vasoactive agents, pressure, stretch and osmotic changes. Emerging evidence suggests that vascular TRPM7 function might be altered in hypertension. The present review discusses the importance of Mg(2+) in vascular biology in hypertension and focuses on transport systems, mainly TRPM7, that might play a role in the control of vascular Mg(2+) homeostasis. Elucidation of the relationship between the complex systems responsible for regulation of Mg(2+) homeostasis, the role of TRPM7 in vascular signaling, and the cardiovascular impact will be important for understanding the clinical implications of hypomagnesemia in cardiovascular disease.

Implications of magnesium deficiency in type 2 diabetes: a review

Magnesium is the fourth most abundant cation in the body and plays an important physiological role in many of its functions. It plays a fundamental role as a cofactor in various enzymatic reactions involving energy metabolism. Magnesium is a cofactor of various enzymes in carbohydrate oxidation and plays an important role in glucose transporting mechanism of the cell membrane. It is also involved in insulin secretion, binding, and activity. Magnesium deficiency and hypomagnesemia can result from a wide variety of causes, including deficient magnesium intake, gastrointestinal, and renal losses. Chronic magnesium deficiency has been associated with the development of insulin resistance. The present review discusses the implications of magnesium deficiency in type 2 diabetes.

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 approximately 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.

Long-term effect of magnesium consumption on the risk of symptomatic gallstone disease among men

BACKGROUND

Magnesium deficiency can cause dyslipidemia and insulin hypersecretion, which may facilitate gallstone formation. However, the effect of long-term consumption of magnesium on the risk of gallstone disease is unknown.

METHODS

We prospectively studied magnesium consumption and risk of gallstone disease in a cohort of 42,705 U.S. men from 1986 to 2002. Magnesium consumption was assessed using a validated semiquantitative food frequency questionnaire. Newly diagnosed gallstone disease was ascertained biennially.

RESULTS

We documented 2,195 incident cases of symptomatic gallstones during 560,810 person-years of follow-up. The age-adjusted relative risks (RRs) for men with total magnesium intake and dietary magnesium, when the highest and lowest quintiles were compared, were 0.67 (95% confidence interval [CI] 0.59-0.77, P for trend <0.0001) and 0.67 (CI 0.59-0.76, P for trend <0.0001), respectively. After adjusting for multiple potential confounding variables, when extreme quintiles were compared, the multivariate RR of total magnesium intake (RR 0.72, CI 0.61-0.86, P for trend = 0.006) and dietary magnesium (RR 0.68, CI 0.57-0.82, P for trend = 0.0006) remained significant with a dose-response relationship.

CONCLUSIONS

Our findings suggest a protective role of magnesium consumption in the prevention of symptomatic gallstone disease among men.

Relationship between serum magnesium values, lipids and anthropometric risk factors

Serum magnesium (SMg) has been reported to negatively correlate with an atherogenic lipid profile in individuals with diabetes mellitus (DM) and metabolic syndrome. This study examines whether the relationships between SMg levels and biochemical and anthropometric risk factors for these conditions are also present in the general adult population.

DESIGN AND METHODS

Biochemical parameters and anthropometric variables were assessed in 1318 healthy adult subjects recruited from the Newfoundland population.

RESULTS

SMg positively correlated with age, and serum phosphate, calcium, albumin, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglyceride levels. SMg negatively correlated with HOMA-beta and percent body fat measured by DEXA. On sub-grouping subjects according to sex, menopausal status or after excluding subjects with DM, only a significant correlation of SMg with albumin, calcium, phosphate, and total cholesterol was common to all. Stepwise linear regression analysis revealed albumin, phosphate, age, total cholesterol, glucose, and body mass index as independent predictors of SMg levels.

CONCLUSIONS

These results indicate that SMg levels positively correlate with total cholesterol and possibly all lipoproteins in a large adult study population which suggests that variation of SMg with serum lipid levels may be different in healthy individuals compared with those with DM. We speculate on a possible binding interaction.

Ionized magnesium supplementation in critically ill patients: comparing ionized and total magnesium

PURPOSE

The purpose of this study was to assess the effect of magnesium supplementation on total magnesium, ionized magnesium, ionized calcium, potassium, and pH in critically ill cancer patients and to compare the validity of the measurements.

MATERIALS AND METHODS

Thirty-three consecutive critically ill patients receiving magnesium supplementation were placed in this prospective observational study at the Comprehensive Cancer Center, University Hospital. One gram (4.1 mmol) magnesium in 50 mL D5W was administered to critically ill patients, and the following were measured: total magnesium, ionized magnesium, ionized calcium, potassium, albumin, pH, BUN, creatinine, creatinine.

RESULTS

Total magnesium and ionized magnesium increased by a mean of .11 +/- .02 and .05 +/- .01 mmol/L, respectively, after supplementation with 4.1 mmol of magnesium sulfate (P = .0001). Total magnesium, ionized magnesium, albumin, ionized calcium, potassium, and pH did not change significantly by the administration of 1 g of magnesium sulfate.

CONCLUSION

The mean ionized magnesium (IMg+2) relationship to total magnesium (TMg) cannot be predicted before the supplementation with the available technology. After supplementation of 4.1 mmol/L the ionized magnesium level increased by .05 +/- .01 mmol/L. Magnesium supplementation had no significant effect on ionized calcium, potassium, and pH. TMg and IMg+2 should be followed independently.

Magnesium status in idiopathic calcium urolithiasis--an orientational study in younger males

With the aim of revealing a possible magnesium (Mg) deficiency in the aetiology of idiopathic recurrent calcium urolithiasis we studied the Mg content of red blood cells, serum total, protein-bound, ionised and complexed fractions of Mg, and urinary Mg after an overnight fast. The two study groups comprised 12 male recurrent calcium urolithiasis patients and 12 healthy male controls (mean age 31 and 29 years, respectively). In recurrent calcium urolithiasis, serum albumin and Mg of erythrocytes were significantly decreased, as was serum total and protein-bound Mg, whereas serum ultrafiltrable, ionised and complexed Mg were statistically indistinguishable from values in controls. Urinary Mg (per unit creatinine) in recurrent calcium urolithiasis (mean 0.188 vs 0.209 in controls; p = 0.386) was not statistically different, whereas urinary total protein, glucose, and pH were significantly increased. The renal clearances of Mg and glucose were positively correlated (r = 0.56; p < 0.01), with a steeper slope in recurrent calcium urolithiasis than controls. Further fractionation of serum and urinary Mg into ions and complexes in recurrent calcium urolithiasis subjects with identical creatinine clearance revealed no statistical difference between 1) Mg ions and complexes filtered by renal glomeruli; 2) Mg ions and complexes excreted in urine; 3) fractional Mg excretion. Median urine supersaturation with respect to calcium oxalate was insignificantly lower (1.5 vs 2.2), with respect to hydroxyapatite insignificantly higher (3.3 vs 1.8), than in controls. It is concluded that relatively young recurrent calcium urolithiasis patients exhibit a deficiency of Mg in erythrocytes and serum total Mg, but no alteration of renal Mg handling. Thus, in recurrent calcium urolithiasis, a role of Mg deficiency in urine as a factor initiating stone formation may be ruled out, whereas a possible link between cellular Mg deficiency and the impairment of renal tubular functions involved in reabsorption of glucose and proteins, and in urine acidification, deserves further studies.