Magnesium and the inflammatory response: potential physiopathological implications

Fruit and vegetable intake and related nutrients are associated with oxidative stress markers in middle-aged men

OBJECTIVE

The aim of this cross-sectional study was to assess the potential relationships between fruit and vegetable (FV) intake and oxidative stress markers in middle-aged men, with an emphasis on vitamin C, fiber, and magnesium content.

METHODS

The study was conducted with 296 healthy men, age 50.5 ± 5.0 y, and body mass index (BMI) of 25.8 ± 3.5 kg/m(2). Dietary intake, anthropometry, blood pressure, lifestyle features, and blood and urine biochemical data were assessed with validated procedures. The oxidative stress markers selected were plasma oxidized low-density lipoprotein (ox-LDL), urinary 8-iso-prostaglandin F2 α (8-iso-PGF2 α) and 8-hydroxy-2'-deoxyguanosine (8-OHdG).

RESULTS

The men included in the highest tertile of FV intake (≥341.1 g/d) displayed lower concentrations of ox-LDL, 8-iso-PGF2 α and 8-OHdG (P for trend < 0.05), regardless of confounding factors. Concentrations of ox-LDL were negatively associated with fiber from the FV intake (P for trend < 0.05) regardless of confounding factors. ox-LDL and 8-OHdG concentrations tended to be lower in the higher tertile of magnesium (P for trend = 0.06) and vitamin C from FV intake (P for trend = 0.05), respectively. Additionally, concentrations of 8-iso-PGF2 α were lower in men in the highest tertile of fiber (≥6.5 g/d; P for trend = 0.034), vitamin C (≥98.0 mg/d; P for trend = 0.007), and magnesium (≥48.9 mg/d; P for trend = 0.018) from the FV-group intake.

CONCLUSIONS

Greater FV intake was independently associated with reduced ox-LDL, 8-OHdG, and 8-iso-PGF2 α in middle-aged men. Fiber, vitamin C, and magnesium from FV seem to contribute to this beneficial relationship.

The role of iron-induced fibrin in the pathogenesis of Alzheimer's disease and the protective role of magnesium

Amyloid hypothesis of Alzheimer's disease (AD) has recently been challenged by the increasing evidence for the role of vascular and hemostatic components that impair oxygen delivery to the brain. One such component is fibrin clots, which, when they become resistant to thrombolysis, can cause chronic inflammation. It is not known, however, why some cerebral thrombi are resistant to the fibrinolytic degradation, whereas fibrin clots formed at the site of vessel wall injuries are completely, although gradually, removed to ensure proper wound healing. This phenomenon can now be explained in terms of the iron-induced free radicals that generate fibrin-like polymers remarkably resistant to the proteolytic degradation. It should be noted that similar insoluble deposits are present in AD brains in the form of aggregates with Abeta peptides that are resistant to fibrinolytic degradation. In addition, iron-induced fibrin fibers can irreversibly trap red blood cells (RBCs) and in this way obstruct oxygen delivery to the brain and induce chronic hypoxia that may contribute to AD. The RBC-fibrin aggregates can be disaggregated by magnesium ions and can also be prevented by certain polyphenols that are known to have beneficial effects in AD. In conclusion, we argue that AD can be prevented by: (1) limiting the dietary supply of trivalent iron contained in red and processed meat; (2) increasing the intake of chlorophyll-derived magnesium; and (3) consumption of foods rich in polyphenolic substances and certain aliphatic and aromatic unsaturated compounds. These dietary components are present in the Mediterranean diet known to be associated with the lower incidence of AD and other degenerative diseases.

Effects of two different strategies of fluid administration on inflammatory mediators, plasma electrolytes and acid/base disorders in patients undergoing major abdominal surgery: a randomized double blind study

BACKGROUND

Administration of normal saline might increase circulating levels of pro-inflammatory cytokines and may cause variation of plasmatic electrolytic and hyperchloremic acidosis, which in turn can impair renal function. Hence the use of balanced solutions could influence the inflammatory cascade triggered by the surgical procedures, the plasmatic electrolyte concentration, the acid-base equilibrium, and the renal function.

METHODS

This is a double blind randomized trial. Forty patients undergoing major abdominal surgery (bowel cancer) were allocated in two groups, the balanced solution (BS) group in which the fluids administered were balanced solutions (colloids and crystalloids); and the unbalanced solution (UBS) group in which the fluids administered were unbalanced solutions (colloids and crystalloids). Measurements were performed after anaesthesia induction (T0), at the end of surgery (T1), within 2 h after surgery (T2) and 24 h after the beginning of surgery (T3). The following data were collected: 1) active matrix metalloproteinase 9 (MMP-9) and its tissue inhibitor (TIMP-1), IL-6, IL-8, IL-10; 2) blood gases variables; 3) electrolytes, albumin, total serum protein and the strong ion difference; 4) neutrophil gelatinase-associated lipocalin (NGAL) from urinary sample.

RESULTS

The BS group exhibited higher circulating level of IL-10 and TIMP-1 and lower level of active MMP-9. The UBS group experienced hypercloremia, hypocalcemia, hypomagnesemia, worse acid-base equilibrium and higher level of NGAL.

CONCLUSIONS

The use of balanced solutions was responsible of less alteration of plasmatic electrolytes, acid-base equilibrium, kidney function and it might be associated with an early anti-inflammatory mechanisms triggering.

TRIAL REGISTRATION

ClinicalTrials.gov (Ref: NCT01320891).

Magnesium and osteoporosis: current state of knowledge and future research directions

A tight control of magnesium homeostasis seems to be crucial for bone health. On the basis of experimental and epidemiological studies, both low and high magnesium have harmful effects on the bones. Magnesium deficiency contributes to osteoporosis directly by acting on crystal formation and on bone cells and indirectly by impacting on the secretion and the activity of parathyroid hormone and by promoting low grade inflammation. Less is known about the mechanisms responsible for the mineralization defects observed when magnesium is elevated. Overall, controlling and maintaining magnesium homeostasis represents a helpful intervention to maintain bone integrity.

Magnesium: novel applications in cardiovascular disease--a review of the literature

Magnesium is an ubiquitous element and its formulation determines its efficacy and administration. It is used for gastrointestinal and obstetric disease and recently cardiovascular and neurological indications have also been explored. The role of serum/dietary magnesium intake on cardiovascular disease, carotid intima-media thickness (CIMT), hypertension (HTN) and cholesterol synthesis has been investigated. Despite differences in patient populations, some observational and interventional studies have suggested that low serum/dietary magnesium is associated with higher CIMT and more cardiovascular risk factors. A few clinical and basic science interventional studies have also shown the benefits of magnesium administration in cardiovascular disease prevention and as a neuroprotective agent. Low magnesium levels have been implicated in inflammation and endothelial dysfunction. Hypomagnesemia results in increased C-reactive protein and cytokine exaggeration, increased nuclear factor kappa B and platelet dysfunction, which can lead to thrombosis. Magnesium appears to play a vital function in cardiovascular stability and health, but an optimal dose and formulation has not been defined. Potentially promising avenues include the combination of magnesium with a statin to reduce cholesterol, C-reactive protein and CIMT, and its early use to reduce stroke morbidity and mortality. Understanding the role of magnesium in inflammation and mineralization and how it has the potential for playing a role in modulating cardiovascular and neurological disease can be a new frontier in medicine.

Lack of influence of serum magnesium levels on overall mortality and cardiovascular outcomes in patients with advanced chronic kidney disease

Background. Low serum magnesium has been associated with an increased cardiovascular risk in the general population and in dialysis patients. Our aim was to analyze the influence of serum magnesium on overall mortality and cardiovascular outcomes in patients with advanced CKD not yet on dialysis. Methods. Seventy patients with CKD stages 4 and 5 were included. After a single measurement of s-magnesium, patients were followed a mean of 11 months. Primary end-point was death of any cause, and secondary end-point was the occurrence of fatal or nonfatal CV events. Results. Basal s-magnesium was within normal range (2.1 ± 0.3 mg/dL), was lower in men (P = 0.008) and in diabetic patients (P = 0.02), and was not different (P = 0.2) between patients with and without cardiopathy. Magnesium did not correlate with PTH, calcium, phosphate, albumin, inflammatory parameters (CRP), and cardiac (NT-proBNP) biomarkers but correlated inversely (r = −0.23; P = 0.052) with the daily dose of loop diuretics. In univariate and multivariate Cox proportional hazard models, magnesium was not an independent predictor for overall mortality or CV events. Conclusions. Our results do not support that serum magnesium can be an independent predictor for overall mortality or future cardiovascular events among patients with advanced CKD not yet on dialysis.

The role of Mg2+ in immune cells

The physiological and clinical relevance of Mg(2+) has evolved over the last decades. The molecular identification of multiple Mg(2+) transporters (Acdp2, MagT1, Mrs2, Paracellin-1, SLC41A1, SLC41A2, TRPM6 and TRPM7) and their biophysical characterization in recent years has improved our understanding of Mg(2+) homeostasis regulation and has provided a basis for investigating the role of Mg(2+) in the immune system. Deletions and mutations of Mg(2+) transporters produce severe phenotypes with more systemic symptoms than those seen with Ca(2+) channel deletions, which tend to be more specific and less profound. Deficiency of the Mg(2+) permeable ion channels TRPM6 or TRPM7 in mice is lethal at embryonic day 12.5 or at day 6.5, respectively, and, even more surprisingly, chicken DT40 B cells lacking TRPM7 die after 24-48 h. Recent progress made in Mg(2+) research has helped to define underlying mechanisms of two hereditary diseases, human Hypomagnesemia (TRPM6 deletion) and X-chromosomal immunodeficiency (MagT1 deletion), and has revealed a potential new role for Mg(2+) as a second messenger. Future elucidation of human Mg(2+) transporters (Mrs2, SLC41A1, SLC41A2, TRPM7) expressed in immunocytes, beyond MagT1 and TRPM6, will widen our knowledge about the potential role of Mg(2+) in the activation of the immune response.

Magnesium deficiency results in an increased formation of osteoclasts

Magnesium (Mg(2+)) deficiency is a frequently occurring disorder that leads to loss of bone mass, abnormal bone growth and skeletal weakness. It is not clear whether Mg(2+) deficiency affects the formation and/or activity of osteoclasts. We evaluated the effect of Mg(2+) restriction on these parameters. Bone marrow cells from long bone and jaw of mice were seeded on plastic and on bone in medium containing different concentrations of Mg(2+) (0.8 mM which is 100% of the normal value, 0.4, 0.08 and 0 mM). The effect of Mg(2+) deficiency was evaluated on osteoclast precursors for their viability after 3 days and proliferation rate after 3 and 6 days, as was mRNA expression of osteoclastogenesis-related genes and Mg(2+)-related genes. After 6 days of incubation, the number of tartrate resistant acid phosphatase-positive (TRACP(+)) multinucleated cells was determined, and the TRACP activity of the medium was measured. Osteoclastic activity was assessed at 8 days by resorption pit analysis. Mg(2+) deficiency resulted in increased numbers of osteoclast-like cells, a phenomenon found for both types of marrow. Mg(2+) deficiency had no effect on cell viability and proliferation. Increased osteoclastogenesis due to Mg(2+) deficiency was reflected in higher expression of osteoclast-related genes. However, resorption per osteoclast and TRACP activity were lower in the absence of Mg(2+). In conclusion, Mg(2+) deficiency augmented osteoclastogenesis but appeared to inhibit the activity of these cells. Together, our in vitro data suggest that altered osteoclast numbers and activity may contribute to the skeletal phenotype as seen in Mg(2+) deficient patients.

Increased dietary fruit intake was associated with lower burden of carotid atherosclerosis in Chinese patients with Type 2 diabetes mellitus

BACKGROUND

Previous studies demonstrated that high fruit consumption was associated with a lower risk of cardiovascular events in patients with Type 2 diabetes mellitus. However, the relationship between fruit intake and carotid atherosclerosis in these patients is unknown. We studied the relationship between dietary fruit intake and carotid intima-media thickness in patients with Type 2 diabetes.

METHODS

A total of 255 Chinese patients with Type 2 diabetes were recruited. Dietary fruit intake was assessed by a validated food-frequency questionnaire, and carotid intima-media thickness was measured by high-resolution ultrasonography.

RESULTS

Among patients with three different tertiles of fruit intake (14.5 ± 8.6 vs. 41.5 ± 7.1 vs. 92.6 ± 39.7 g/day), there was no difference in their clinical characteristics (all P > 0.05). Patients with the highest tertile of fruit intake had a significantly higher BMI and diastolic blood pressure than those with the lowest tertile intake. Furthermore, serum high-sensitivity C-reactive protein, 8-isoprostane and superoxide dismutase were similar among the three tertiles of patients (all P > 0.05). However, patients with the highest tertile of fruit intake had lower carotid intima-media thickness (0.97 ± 0.02 vs. 1.08 ± 0.03 mm, P = 0.046) and prevalence of carotid plaque (11.76 vs. 1.18%, P = 0.022) than those with the lowest tertile of fruit intake. Multivariate regression analysis revealed the highest tertile of fruit intake (β = -0.086, P = 0.049) was independently associated with carotid intima-media thickness.

CONCLUSIONS

Our results demonstrated that, in Chinese patients with Type 2 diabetes, higher dietary fruit intake was associated with a lower burden of carotid atherosclerosis as reflected by lower carotid intima-media thickness and prevalence of carotid plaque.

Magnesium in health and disease

Mammalian cells tightly regulate cellular Mg(2+) content through a variety of transport and buffering mechanisms under the control of various hormones and cellular second messengers. The effect of these hormones and agents results in dynamic changes in the total content of Mg(2+) being transported across the cell membrane and redistributed within cellular compartments. The importance of maintaining proper cellular Mg(2+) content optimal for the activity of various cellular enzymes and metabolic cycles is underscored by the evidence that several diseases are characterized by a loss of Mg(2+) within specific tissues as a result of defective transport, hormonal stimulation, or metabolic impairment. This chapter will review the key mechanisms regulating cellular Mg(2+) homeostasis and their impairments under the most common diseases associated with Mg(2+) loss or deficiency.

Organomagnesium suppresses inflammation-associated colon carcinogenesis in male Crj: CD-1 mice

Magnesium (Mg) deficiency increases genomic instability and Mg intake has been reported to be inversely associated with a risk of colorectal cancer (CRC). This study was designed to determine whether organo-Mg in drinking water suppresses inflammation-associated colon carcinogenesis in mice. Male Crj: CD-1 mice were initiated with a single i.p. injection of azoxymethane (AOM, 10mg/kg body weight) and followed by a 1 week exposure to dextran sulfate sodium (DSS, 1.5%, w/v) in drinking water to induce colonic neoplasms. They were then given the drinking water containing 7, 35 or 175 p.p.m. organo-Mg for 13 weeks. The chemopreventive efficacy of organo-Mg was determined 16 weeks after the AOM exposure. Administration with organo-Mg at all doses caused a significant inhibition of CRC development (P < 0.01 and P < 0.001). Especially, the highest dose of organo-Mg significantly suppressed the occurrence of all the colonic pathological lesions (mucosal ulcer, dysplasia, adenoma and adenocarcinoma). Organo-Mg also significantly reduced the number of mitoses/anaphase bridging, as well as proliferation of CRC. Additionally, at week 4, organo-Mg lowered the messenger RNA expression of certain proinflammatory cytokines, such as interleukin-1β, interleukin-6, interferon-γ and inducible nitric oxide synthase in the lesion-free colorectal mucosa at week 4 but increased the Nrf-2 messenger RNA expression. Our findings that organo-Mg inhibits inflammation-related mouse colon carcinogenesis by modulating the proliferative activities and chromosomal instability of CRC and suppressing colonic inflammation may suggest potential use of organo-Mg for clinical chemoprevention trials of CRC in the inflamed colon.

The efficacy of magnesium sulfate loading on microalbuminuria following SIRS: One step forward in dosing

Backgrounds

Magnesium has been known for its antioxidative and antiinflammatory properties in many studies. In this study two dosing regimens of magnesium were compared with a placebo control group in order to investigate safety and efficacy of high doses of intravenous magnesium sulfate infusion on critically ill trauma patients. Inflammatory and oxidative factors were measured in this trial.

Methods

45 trauma patients with systemic inflammatory response syndromes (SIRS) were randomly assigned into 2 treatment and one placebo groups. The high dose group received 15 g MgSO₄, low dose group received 7.5 g of MgSO₄ over 4 hour infusion, and placebo group received saline alone. The initial and post magnesium sulfate injections levels of tumor necrosis factor alpha (TNF-α), total antioxidant power and lipid peroxidation were measured after 6, 18 and 36 hours. The pre-infusion along with 6 and 36 hour level of microalbuminuria were also determined.

Results

Repeated measurements illustrated that there was no significant difference in TNF-α, total antioxidant power and lipid peroxidation levels among groups during the period of analysis. The microalbuminuria at 36 hour post infusion of high dose group was lower than that of control group (p = 0.024). Patient’s mortality (28 day) was similar among all treatment groups. Both magnesium infusion groups tolerated the drug without experiencing any complications.

Conclusion

No evidence for antioxidative and antiinflammatory effects of magnesium in traumatic SIRS positive patients was found. Magnesium in high doses may be recommended for traumatic patients with SIRS status to prevent microalbuminuria.

Relationship between serum magnesium levels and cardiovascular events in chronic kidney disease patients

BACKGROUND

Magnesium is an essential ion for all living cells because over 300 enzymes require the presence of magnesium for their catalytic action. To date, no group has evaluated magnesium as a cardiovascular risk factor in chronic kidney disease (CKD) subjects, in which closely interrelated factors and potential confounders such as endothelial dysfunction, insulin resistance (the homeostasis model assessment (HOMA) index) and inflammation (expressed as serum C-reactive protein (CRP) levels) were also considered.

METHODS

Between March 2006 and December 2010, 283 CKD patients were followed up for time-to-event analysis until the occurrence of fatal or nonfatal cardiovascular events. Endothelium-dependent vasodilatation (flow-mediated dilatation; FMD) and endothelium-independent vasodilatation (nitroglycerin-mediated dilatation) of the brachial artery were assessed noninvasively using high-resolution ultrasound.

RESULTS

From the univariate analysis of FMD, it appears that a higher magnesium level is associated with less endothelial dysfunction. When a multivariate analysis was performed, magnesium and estimated glomerular filtration rates (eGFR) maintained a strong positive correlation with FMD, supporting the hypothesis that higher levels of magnesium may protect against endothelial damage. In univariate Cox proportional hazards models, FMD, magnesium, high sensitivity CRP, the HOMA index, eGFR, comorbid diabetes, hypertension, smoking status, systolic blood pressure, serum phosphate and intact parathormone emerged as significant predictors for cardiovascular outcomes. Kaplan-Meier curves showed significantly higher cardiovascular mortality rates in CKD patients whose serum magnesium levels were below 2.05 mg/dl.

CONCLUSIONS

This observational cohort study showed that magnesium may be an independent predictor of future cardiovascular outcomes and is the first study demonstrating such a role in etiologically diagnosed CKD patients, across different stages.

Magnesium and its transporters in cancer: a novel paradigm in tumour development

The relationship between magnesium and cancer is not as simple as could be assumed from the well-established requirement of magnesium for cell proliferation. Basic and pre-clinical studies indicate that magnesium deficiency can have both anti- and pro-tumour effects. In the present review, we briefly outline the new findings on the role of magnesium in angiogenesis and metastatization, and focus on the relationship between tumour cell proliferation and metabolic reprogramming, discussing how magnesium and its transporters are involved in these processes. The role of magnesium in cancer is also critically examined with regard to mitochondrial function, apoptosis and resistance to treatment. Finally, we bring together the latest experimental evidence indicating that alteration in the expression and/or activity of magnesium channels is a frequent finding in cancer cells and human tumour tissues examined to date, and we discuss the potential implications for developing novel diagnostic and therapeutic strategies.

X-ray structures of magnesium and manganese complexes with the N-terminal domain of calmodulin: insights into the mechanism and specificity of metal ion binding to an EF-hand

Calmodulin (CaM), a member of the EF-hand superfamily, regulates many aspects of cell function by responding specifically to micromolar concentrations of Ca(2+) in the presence of an ~1000-fold higher concentration of cellular Mg(2+). To explain the structural basis of metal ion binding specificity, we have determined the X-ray structures of the N-terminal domain of calmodulin (N-CaM) in complexes with Mg(2+), Mn(2+), and Zn(2+). In contrast to Ca(2+), which induces domain opening in CaM, octahedrally coordinated Mg(2+) and Mn(2+) stabilize the closed-domain, apo-like conformation, while tetrahedrally coordinated Zn(2+) ions bind at the protein surface and do not compete with Ca(2+). The relative positions of bound Mg(2+) and Mn(2+) within the EF-hand loops are similar to those of Ca(2+); however, the Glu side chain at position 12 of the loop, whose bidentate interaction with Ca(2+) is critical for domain opening, does not bind directly to either Mn(2+) or Mg(2+), and the vacant ligand position is occupied by a water molecule. We conclude that this critical interaction is prevented by specific stereochemical constraints imposed on the ligands by the EF-hand β-scaffold. The structures suggest that Mg(2+) contributes to the switching off of calmodulin activity and possibly other EF-hand proteins at the resting levels of Ca(2+). The Mg(2+)-bound N-CaM structure also provides a unique view of a transiently bound hydrated metal ion and suggests a role for the hydration water in the metal-induced conformational change.

Hypomagnesemia in type 2 diabetic nephropathy: a novel predictor of end-stage renal disease

OBJECTIVE

There is now growing evidence that magnesium (Mg) deficiency is implicated in type 2 diabetes and its complications. However, it has not been fully elucidated whether hypomagnesemia is a predictor of end-stage renal disease (ESRD) in type 2 diabetic nephropathy.

RESEARCH DESIGN AND METHODS

This retrospective cohort study included 455 chronic kidney disease (CKD) patients (144 with type 2 diabetic nephropathy and 311 with nondiabetic CKD) who were hospitalized at Osaka General Medical Center for a CKD educational program between April 2001 and December 2007. The primary outcome was progression to renal replacement therapy. Participants were categorized based on serum Mg level into Low-Mg (serum Mg level ≤1.8 mg/dL) and High-Mg (serum Mg level >1.8 mg/dL) groups with the previously published normal lower limit chosen as the cutoff point.

RESULTS

Of the subjects with type 2 diabetic nephropathy, 102 progressed to ESRD during follow-up (median, 23 months). A multivariate Cox proportional hazards model showed that after adjustment for various demographic factors and laboratory data, the Low-Mg group had a 2.12-fold higher risk of ESRD than the High-Mg group (95% CI 1.28-3.51; P = 0.004). In contrast, 135 of the nondiabetic CKD subjects progressed to ESRD during follow-up (median, 44 months). No significant difference in outcome was found between the Low- and High-Mg groups of this population (adjusted hazard ratio, 1.15; 95% CI 0.70-1.90; P = 0.57).

CONCLUSIONS

Hypomagnesemia is a novel predictor of ESRD in patients with type 2 diabetic nephropathy.

Magnesium and calcium deficiencies additively increase zinc concentrations and metallothionein expression in the rat liver

Mg deficiency increases the concentration of Zn in the liver. We investigated the effect of Mg deficiency on the expression of Zn-regulating factors such as Zn transporters and metallothionein (MT) in the rat liver. Because Ca deficiency alleviates some of the effects of Mg deficiency, we also investigated the interactions associated with Ca and Mg deficiencies. Growing male rats were given a control diet, a Mg-deficient diet, a Ca-deficient diet and a Mg- and Ca-deficient diet for 3 weeks. Mg and Ca deficiencies additively increased the mRNA levels of MT-1 and MT-2, the MT protein concentration and the concentration of Zn in the liver. The hepatic mRNA level of Zip14 increased with Mg deficiency but not with Ca deficiency. The dietary treatments did not affect the mRNA levels of other Zn transporters such as Zip1, Zip5, ZnT1, ZnT5 and ZnT6 in the liver. Ca deficiency was found to decrease the amount of femoral Zn and increase serum Zn concentration. This did not occur in the case of Mg deficiency. These results suggest that Mg deficiency enhances hepatic Zn uptake by the up-regulation of Zip14 expression and increases hepatic Zn concentration, leading to the enhancement of MT expression. Ca deficiency causes a transfer of Zn from the bone to the liver, which increases hepatic Zn concentration and, in turn, up-regulates the expression of MT. Because Mg and Ca deficiencies increase hepatic Zn concentration and increase MT expression by different mechanisms, their effects are additive.

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.

Endothelial cells and magnesium: implications in atherosclerosis

There is no doubt that the functional and structural integrity of the endothelium is critical in maintaining vascular homoeostasis and in preventing atherosclerosis. In the light of epidemiological and experimental studies, magnesium deficiency is emerging as an inducer of endothelial dysfunction. In particular, data on the effects of low extracellular magnesium on cultured endothelial cells reinforce the idea that correcting magnesium homoeostasis might be a helpful and inexpensive intervention to prevent and treat endothelial dysfunction and, consequently, atherosclerosis.

Magnesium and vascular changes in hypertension

Many factors have been implicated in the pathogenesis of hypertension, including changes in intracellular concentrations of calcium, sodium, potassium, and magnesium. There is a significant inverse correlation between serum magnesium and incidence of cardiovascular diseases. Magnesium is a mineral with important functions in the body such as antiarrhythmic effect, actions in vascular tone, contractility, glucose metabolism, and insulin homeostasis. In addition, lower concentrations of magnesium are associated with oxidative stress, proinflammatory state, endothelial dysfunction, platelet aggregation, insulin resistance, and hyperglycemia. The conflicting results of studies evaluating the effects of magnesium supplements on blood pressure and other cardiovascular outcomes indicate that the action of magnesium in the vascular system is present but not yet established. Therefore, this mineral supplementation is not indicated as part of antihypertensive treatment, and further studies are needed to better clarify the role of magnesium in the prevention and treatment of cardiovascular diseases.

Natural plant products and extracts that reduce immunoexcitotoxicity-associated neurodegeneration and promote repair within the central nervous system

Our understanding of the pathophysiological and biochemical basis of a number of neurological disorders has increased enormously over the last three decades. Parallel with this growth of knowledge has been a clearer understanding of the mechanism by which a number of naturally occurring plant extracts, as well as whole plants, can affect these mechanisms so as to offer protection against injury and promote healing of neurological tissues. Curcumin, quercetin, green tea catechins, balcalein, and luteolin have been extensively studied, and they demonstrate important effects on cell signaling that go far beyond their antioxidant effects. Of particular interest is the effect of these compounds on immunoexcitotoxicity, which, the authors suggest, is a common mechanism in a number of neurological disorders. By suppressing or affecting microglial activation states as well as the excitotoxic cascade and inflammatory mediators, these compounds dramatically affect the pathophysiology of central nervous system disorders and promote the release and generation of neurotrophic factors essential for central nervous system healing. We discuss the various aspects of these processes and suggest future directions for study.

Thrombotic microangiopathy: a role for magnesium?

Despite advances in more recent years, the pathophysiology and especially treatment modalities of thrombotic microangiopathy (TMA) largely remain enigmatic. Disruption of endothelial homeostasis plays an essential role in TMA. Considering the proven causal association between magnesium and both endothelial function and platelet aggregability, we speculate that a magnesium deficit could influence the course of TMA and the related haemolytic uraemic syndrome and thrombotic thrombocytopenic purpura. A predisposition towards TMA is seen in many conditions with both extracellular and intracellular magnesium deficiency. We propose a rationale for magnesium supplementation in TMA, in analogy with its evidence-based therapeutic application in pre-eclampsia and suggest, based on theoretical grounds, that it might attenuate the development of TMA, minimise its severity and prevent its recurrence. This is based on several lines of evidence from both in vitro and in vivo data showing dose-dependent effects of magnesium supplementation on nitric oxide production, platelet aggregability and inflammation. Our hypothesis, which is further amenable to assessment in animal models before therapeutic applications in humans are implemented, could be explored both in vitro and in vivo to decipher the potential role of magnesium deficit in TMA and of the effects of its supplementation.

Nitric oxide mediates low magnesium inhibition of osteoblast-like cell proliferation

An adequate intake of magnesium (Mg) is important for bone cell activity and contributes to the prevention of osteoporosis. Because (a) Mg is mitogenic for osteoblasts and (b) reduction of osteoblast proliferation is detected in osteoporosis, we investigated the influence of different concentrations of extracellular Mg on osteoblast-like SaOS-2 cell behavior. We found that low Mg inhibited SaOS-2 cell proliferation by increasing the release of nitric oxide through the up-regulation of inducible nitric oxide synthase (iNOS). Indeed, both pharmacological inhibition with the iNOS inhibitor l-N(6)-(iminoethyl)-lysine-HCl and genetic silencing of iNOS by small interfering RNA restored the normal proliferation rate of the cells. Because a moderate induction of nitric oxide is sufficient to potentiate bone resorption and a relative deficiency in osteoblast proliferation can result in their inadequate activity, we conclude that maintaining Mg homeostasis is relevant to ensure osteoblast function and, therefore, to prevent osteoporosis.

Effect of magnesium deficiency on various mineral concentrations in rat liver

Magnesium (Mg) deficiency is well known to affect metabolism of some trace minerals. We investigated the effect of Mg deficiency on hepatic concentration of various minerals in rats. Twelve 5-week-old male rats were divided into the groups given a control diet and an Mg-deficient diet. After 4 weeks, liver sample was collected from each rat. The concentrations of 36 minerals were simultaneously determined by a semiquantitative method of inductively coupled plasma-mass spectrometry (ICP-MS). The semiquantitative analysis showed that Mg deficiency significantly increased iron (Fe), copper (Cu), zinc (Zn), gallium (Ga), yttrium (Y), zirconium (Zr), molybdenum (Mo), rhodium (Rh), silver (Ag), and barium (Ba) concentrations, and significantly decreased scandium (Sc) and niobium (Nb) concentrations in rat liver. Then, hepatic Fe, Cu, Zn, Sc, Zr, and Mo concentrations were quantitatively measured, which indicated the similar effects as observed by the semiquantitative analysis. Additionally, the semiquantitative measurements of these minerals were highly correlated to these measurements with the quantitative method, but the measurements were not completely consistent between these analyses. The present study is the first research indicating the changes of hepatic Ga, Y, Zr, Mo, Rh, Ag, Ba, Sc, and Nb concentrations in Mg-deficient rats. The present study also indicates that the semiquantitative analysis with ICP-MS is a valid method for screening analysis to investigate various mineral concentrations in animal tissues.

Background values for essential and toxic elements in children's nails and correlation with hair levels

Human nails are an attractive matrix for assessing environmental exposures to toxic elements as well as the deficiency of essential elements since it is noninvasively collected and can be stored at room temperature. However, reference or baseline levels in nonexposed and healthy populations are not yet established. Then, the aims of this study were (a) to estimate background values for essential and toxic elements in nails from a healthy young population in southern Brazil and (b) to evaluate possible correlations between essential and toxic elements in nails. Furthermore, this report took part of a recent study of background values in the hair of a young population. Thus, correlations between chemical elements in nails and hair were also evaluated. Nails were collected from healthy children (n = 126), and element concentrations were determined by inductively coupled plasma mass spectrometry. This study provides new and reliable reference concentrations for toxic and essential elements in children's nails. The results can be used as reference values for epidemiological or clinical investigations based on trace elements in nails. Additionally, we also showed weak to strong correlations between Cu, Mg, Mn, Se, and Zn levels in nails and hair.

Magnesium deficiency up-regulates Myod expression in rat skeletal muscle and C2C12 myogenic cells

Magnesium (Mg) deficiency induces the production of free radicals, increases cytosolic ionized calcium concentration, and modulates the function of skeletal muscle in rats. The present study examined the effects of Mg deficiency on the gene expression of molecules related to myogenesis in the gastrocnemius muscle as well as in C2C12 myogenic cells. Ingestion of an Mg-deficient diet resulted in a lower weight of the gastrocnemius muscle and higher concentration of muscular TBARSs, an index of oxidative stress. Mg deficiency also enhanced the expression of Myod and myogenin. In vivo effects of Mg deficiency on myogenic gene expression were partially reproduced in in vitro C2C12 cells; expression of Myod was up-regulated by a mixed culture of myoblasts and myotubes with Mg-deficient medium, which related to the simultaneous up-regulation of Myhc IIb, a myotube-specific protein. The culture with Mg-deficient medium did not increase the gene transcript level of HO-1, another marker of oxidative stress, suggesting that Mg deficiency-induced Myod expression does not result from oxidative stress. Furthermore, oxidative stress induced by hydrogen peroxide did not increase Myod expression, whereas the expression of Myod, myogenin and Myhc IIb was decreased by oxidative stress from the initial phase of differentiation. The effects of Mg deficiency depended on the stages of myogenesis; myoblast culture in Mg-deficient differentiation medium did not affect the expression of Myod and Myhc IIb. The present study revealed stage-dependent effects of Mg deficiency on myogenesis.

Risk of anti-EGFR monoclonal antibody-related hypomagnesemia: systematic review and pooled analysis of randomized studies

INTRODUCTION

The typical class side effect of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (panitumumab and cetuximab) is a cutaneous maculopapular rash, although hypomagnesemia is also described to be a frequent adverse event. The purpose of our meta-analysis is to evaluate the frequency and the relative risk of hypomagnesemia in patients treated with cetuximab or panitumumab in randomized trials.

AREA COVERED

Eligible studies included prospective randomized Phase III controlled trials in which cetuximab or panitumumab were compared with standard anti-neoplastic therapy or best supportive care. Summary incidence rates and relative risks with 95% confidence intervals were calculated.

EXPERT OPINION

The overall incidence of hypomagnesemia was 17% among the patients who received the treatment, whose risk of developing hypomagnesemia turned out to be significantly increased compared with the patients treated with control medication, with an overall relative risk of 5.83 (p < 0.00001), where 3.87 refers to cetuximab and 12.55 to panitumumab. The addition of anti-EGFR monoclonal antibodies to standard anticancer therapy showed a significantly increased risk of hypomagnesemia compared with controls. The risk seems to be even higher for panitumumab, probably correlated with the increased risk of other adverse events (e.g., diarrhea and dehydration). Hypomagnesemia does not seem to be linked with any serious complications.

Brain protection by rapeseed oil in magnesium-deficient mice

Diets given for 30 days with various mono-(MUFA) and poly-(PUFA) unsaturated fatty acid contents were evaluated for brain protection in magnesium-deficient mice: a commercial and three synthetic diets (n-6PUFA, n-3PUFA and MUFA-based chows enriched with 5% corn/sunflower oils 1:3, with 5% rapeseed oil and with 5% high oleic acid sunflower oil/sunflower oil 7:3, respectively). Unlike magnesium deprivation, they induced significant differences in brain and erythrocyte membrane phospholipid fatty acid compositions. n-3PUFA but not other diets protected magnesium-deficient mice against hyperactivity and moderately towards maximal electroshock- and NMDA-induced seizures. This diet also inhibited audiogenic seizures by 50%, preventing animal deaths. Because, like n-6PUFA diet, matched control MUFA diet failed to induce brain protections, alpha-linolenate (ALA) rather than reduced n-6 PUFA diet content is concluded to cause n-3PUFA neuroprotection. Present in vivo data also corroborate literature in vitro inhibition of T type calcium channels by n-3 PUFA, adding basis to ALA supplementation in human anti-epileptic/neuroprotective strategies.

Microcirculatory changes during open label magnesium sulphate infusion in patients with severe sepsis and septic shock

Background

Microcirculatory alterations play a pivotal role in sepsis and persist despite correction of systemic hemodynamic parameters. Therefore it seems tempting to test specific pro-microcirculatory strategies, including vasodilators, to attenuate impaired organ perfusion. As opposed to nitric oxide donors, magnesium has both endothelium-dependent and non-endothelium-dependent vasodilatory pathways.

Methods

In a single-center open label study we evaluated the effects of magnesium sulphate (MgS) infusion on the sublingual microcirculation perfusion in fluid resuscitated patients with severe sepsis and septic shock within the first 48 hours after ICU admission. Directly prior to and after 1 hour of magnesium sulphate (MgS) infusion (2 gram) systemic hemodynamic variables, sublingual SDF images and standard laboratory tests, were obtained.

Results

Fourteen patients (12 septic shock, 2 severe sepsis) with a median APACHE II score of 20 were enrolled. No significant difference of the systemic hemodynamic variables was found between baseline and after MgS infusion. We did not observe any significant difference pre and post MgS infusion in the primary endpoint microvascular flow index (MFI) of small vessels: 2.25(1.98-2.69) vs. 2.33(1.96-2.62), p = 0.65. Other variables of microcirculatory perfusion were also unaltered. In the overall unchanged microvascular perfusion there was a non-significant trend to an inverse linear relationship between the changes of MFI and its baseline value (y = -0.7260 × + 1.629, r² = 0.270, p = 0.057). The correlation between baseline Mg concentrations and the change in MFI pre- and post MgS infusion was non-significant (r_s = -0.165, p = 0.67).

Conclusions

In the setting of severe sepsis and septic shock sublingual microcirculatory alterations were observed despite fulfillment of sepsis resuscitation guidelines. After infusion of a limited and fixed dose of MgS, microcirculatory perfusion did not improve over time.

Trial registration

ClinicalTrials.gov NTC01332734.

Hepcidin expression in the liver of rats fed a magnesium-deficient diet

Mg deficiency accelerates Fe accumulation in the liver, which may induce various metabolic disturbances. In the present study, we examined the gene expression of Hepcidin, a peptide hormone produced in the liver to regulate intestinal Fe absorption negatively, in Mg-deficient rats. Although liver Fe concentration was significantly higher in rats fed an Mg-deficient diet for 4 weeks than in rats fed a control diet, Hepcidin expression in the liver was comparable between the dietary groups. Previous studies revealed that Fe overload up-regulated Hepcidin expression through transcriptional activation by Fe-induced bone morphogenetic protein (Bmp) 6, a growth/differentiation factor belonging to the transforming growth factor-β family, in the liver. Mg deficiency up-regulated the expression of Bmp6 but did not affect the expression of inhibition of DNA binding 1, a sensitive Bmp-responsive gene. In addition, the expression of Bmp receptors such as activin receptor-like kinase 2 (Alk2), activin receptor type IIA (Actr2a), activin receptor type IIB (Actr2b) and Bmp type II receptor (Bmpr2) was lower in the liver of Mg-deficient rats than in that of control rats. The present study indicates that accumulation of hepatic Fe by Mg deficiency is a stimulant inducing Bmp6 expression but not Hepcidin expression by blunting Bmp signalling possibly resulting from down-regulation of the receptor expression. Unresponsive Hepcidin expression may have a role in Mg deficiency-induced changes related to increased liver Fe.

Magnesium sulfate ameliorates maternal and fetal inflammation in a rat model of maternal infection

OBJECTIVE

Magnesium sulfate is proposed to have neuroprotective effects in the offspring. We examined the effects of maternal magnesium sulfate administration on maternal and fetal inflammatory responses in a rat model of maternal infection.

STUDY DESIGN

Pregnant rats were injected with saline, Gram-negative bacterial endotoxin lipopolysaccharide or lipopolysaccharide with magnesium sulfate (pre- and/or after lipopolysaccharide) to mimic infection. Maternal blood, amniotic fluid, fetal blood, and fetal brains were collected 4 hours after lipopolysaccharide and assayed for tumor necrosis factor, interleukin-6, monocyte chemoattractant protein-1, and growth-related oncogene-KC. In addition, the effect of magnesium sulfate on cytokine production by an astrocytoma cell line was assessed.

RESULTS

Lipopolysaccharide administration induced tumor necrosis factor, interleukin-6, monocyte chemoattractant protein-1, and growth-related oncogene-KC expression in maternal and fetal compartments. Maternal magnesium sulfate treatment significantly attenuated lipopolysaccharide-induced multiple proinflammatory mediator levels in maternal and fetal compartments.

CONCLUSION

Antenatal magnesium sulfate administration significantly ameliorated maternal, fetal, and gestational tissue-associated inflammatory responses in an experimental model of maternal infection.

Synchrotron soft X-ray imaging and fluorescence microscopy reveal novel features of asbestos body morphology and composition in human lung tissues

Background

Occupational or environmental exposure to asbestos fibres is associated with pleural and parenchymal lung diseases. A histopathologic hallmark of exposure to asbestos is the presence in lung parenchyma of the so-called asbestos bodies. They are the final product of biomineralization processes resulting in deposition of endogenous iron and organic matter (mainly proteins) around the inhaled asbestos fibres. For shedding light on the formation mechanisms of asbestos bodies it is of fundamental importance to characterize at the same length scales not only their structural morphology and chemical composition but also to correlate them to the possible alterations in the local composition of the surrounding tissues. Here we report the first correlative morphological and chemical characterization of untreated paraffinated histological lung tissue samples with asbestos bodies by means of soft X-ray imaging and X-Ray Fluorescence (XRF) microscopy, which reveals new features in the elemental lateral distribution.

Results

The X-ray absorption and phase contrast images and the simultaneously monitored XRF maps of tissue samples have revealed the location, distribution and elemental composition of asbestos bodies and associated nanometric structures. The observed specific morphology and differences in the local Si, Fe, O and Mg content provide distinct fingerprints characteristic for the core asbestos fibre and the ferruginous body. The highest Si content is found in the asbestos fibre, while the shell and ferruginous bodies are characterized by strongly increased content of Mg, Fe and O compared to the adjacent tissue. The XRF and SEM-EDX analyses of the extracted asbestos bodies confirmed an enhanced Mg deposition in the organic asbestos coating.

Conclusions

The present report demonstrates the potential of the advanced synchrotron-based X-ray imaging and microspectroscopy techniques for studying the response of the lung tissue to the presence of asbestos fibres. The new results obtained by simultaneous structural and chemical analysis of tissue specimen have provided clear evidence that Mg, in addition to Fe, is also involved in the formation mechanisms of asbestos bodies. This is the first important step to further thorough investigations that will shed light on the physiopathological role of Mg in tissue response to the asbestos toxicity.

Insights into modulation of calcium signaling by magnesium in calmodulin, troponin C and related EF-hand proteins

The Ca(2+)-binding helix-loop-helix structural motif called "EF-hand" is a common building block of a large family of proteins that function as intracellular Ca(2+)-receptors. These proteins respond specifically to micromolar concentrations of Ca(2+) in the presence of ~1000-fold excess of the chemically similar divalent cation Mg(2+). The intracellular free Mg(2+) concentration is tightly controlled in a narrow range of 0.5-1.0mM, which at the resting Ca(2+) levels is sufficient to fully or partially saturate the Ca(2+)-binding sites of many EF-hand proteins. Thus, to convey Ca(2+) signals, EF-hand proteins must respond differently to Ca(2+) than to Mg(2+). In this review the structural aspects of Mg(2+) binding to EF-hand proteins are considered and interpreted in light of the recently proposed two-step Ca(2+)-binding mechanism (Grabarek, Z., J. Mol. Biol., 2005, 346, 1351). It is proposed that, due to stereochemical constraints imposed by the two-EF-hand domain structure, the smaller Mg(2+) ion cannot engage the ligands of an EF-hand in the same way as Ca(2+) and defaults to stabilizing the apo-like conformation of the EF-hand. It is proposed that Mg(2+) plays an active role in the Ca(2+)-dependent regulation of cellular processes by stabilizing the "off state" of some EF-hand proteins, thereby facilitating switching off their respective target enzymes at the resting Ca(2+) levels. Therefore, some pathological conditions attributed to Mg(2+) deficiency might be related to excessive activation of underlying Ca(2+)-regulated cellular processes. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Sphingolipids regulate [Mg2+]o uptake and [Mg2+]i content in vascular smooth muscle cells: potential mechanisms and importance to membrane transport of Mg2+

Sphingolipids have a variety of important signaling roles in mammalian cells. We tested the hypothesis that certain sphingolipids and neutral sphingomyelinase (N-SMase) can regulate intracellular free magnesium ions ([Mg2+]i) in vascular smooth muscle (VSM) cells. Herein, we show that several sphingolipids, including C2-ceramide, C8-ceramide, C16-ceramide, and sphingosine, as well as N-SMase, have potent and direct effects on content and mobilization of [Mg2+]i in primary cultured rat aortic smooth muscle cells. All of these sphingolipid molecules increase, rapidly, [Mg2+]i in these vascular cells in a concentration-dependent manner. The increments of [Mg2+]i, induced by these agents, are derived from influx of extracellular Mg2+ and are extracellular Ca2+ concentration-dependent. Phospholipase C and Ca2+/calmodulin/Ca2+-ATPase activity appear to be important in the sphingolipid-induced rises of [Mg2+]i. Activation of certain PKC isozymes may also be required for sphingolipid-induced rises in [Mg2+]i. These novel results suggest that sphingolipids may be homeostatic regulators of extracellular Mg2+ concentration influx (and transport) and [Mg2+]i content in vascular muscle cells.

Magnesium, inflammation, and obesity in chronic disease

About 60% of adults in the United States do not consume the estimated average requirement for magnesium, but widespread pathological conditions attributed to magnesium deficiency have not been reported. Nevertheless, low magnesium status has been associated with numerous pathological conditions characterized as having a chronic inflammatory stress component. In humans, deficient magnesium intakes are mostly marginal to moderate (approximately 50% to <100% of the recommended dietary allowance). Animal experiments indicate that signs of marginal-to-moderate magnesium deficiency can be compensated or exacerbated by other factors influencing inflammatory and oxidative stress; recent studies suggest a similar happening in humans. This suggestion may have significance in obesity, which is characterized as having a chronic low-grade inflammation component and an increased incidence of a low magnesium status. Marginal-to-moderate magnesium deficiency through exacerbating chronic inflammatory stress may be contributing significantly to the occurrence of chronic diseases such as atherosclerosis, hypertension, osteoporosis, diabetes mellitus, and cancer.

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.

The immunobiology of aluminium adjuvants: how do they really work?

Aluminium adjuvants potentiate the immune response, thereby ensuring the potency and efficacy of typically sparingly available antigen. Their concomitant critical importance in mass vaccination programmes may have prompted recent intense interest in understanding how they work and their safety. Progress in these areas is stymied, however, by a lack of accessible knowledge pertaining to the bioinorganic chemistry of aluminium adjuvants, and, consequently, the inappropriate application and interpretation of experimental models of their mode of action. The objective herein is, therefore, to identify the many ways that aluminium chemistry contributes to the wide and versatile armoury of its adjuvants, such that future research might be guided towards a fuller understanding of their role in human vaccinations.

Magnesium sulfate in emergency department patients with hypertension

To compare the effect of IV magnesium with other antihypertensives in emergency department (ED) patients with hypertension. ED patients with a systolic BP > 135 mmHg or diastolic BP > 85 were approached for entry into the study. Those granting consent were randomly placed into one of three treatment groups: (1) 1.5 gm IV MgSO(4) (n = 42), (2) a parenteral or oral antihypertensive agent (n = 41), (3) both IV MgSO(4) and an antihypertensive agent (n = 44). Systolic and diastolic blood pressures were measured at entry into the study and at 15, 30, 45, and 60 min after magnesium or other antihypertensive medications were given. The main outcome measure was blood pressure at 60 min, and results were compared using one-way analysis of variance with the post hoc Tukey HSD test. Compared to systolic and diastolic blood pressures at time 0, both were lower at 15, 30, 45, and 60 min in all groups (p < 0.05). No significant difference in systolic or diastolic BP at any time point was observed when response to treatment was compared between the three groups. Intravenous MgSO(4) is as effective as antihypertensives at lowering BP in emergency department patients.

Haemato-biochemical responses and induction of HSP70 to dietary phosphorus in Catla catla (Hamilton) fingerlings

A feeding trial of 120 days was conducted to study the effect of graded levels of dietary phosphorus on haematology, serum protein concentrations and HSP70 expression in fingerlings of the Indian major carp, Catla (Catla catla). Eight isonitrogenous and isoenergetic purified diets were formulated to contain graded levels of dietary phosphorus (dP), i.e., T(1), 0.1%; T(2), 0.3%; T(3), 0.5%; T(4), 0.7%; T(5), 0.9%; T(6), 1.1%; T(7), 1.3%; or T(8), 1.5%. Four hundred and eighty fish (average weight 4.23 +/- 0.016 g) were equally distributed into 24 tanks forming eight treatments with three replicates each. The fish were fed daily at the rate of 3.5% body weight in two instalments. At the end of feeding trial fish were sampled to study total RBC and WBC count, haemoglobin, serum lysozyme activity, serum total protein, albumin (A), globulin (G) concentration and HSP70 expression. Total RBC count, haemoglobin concentration and serum lysozyme activity did not vary significantly in response to different dietary phosphorus concentrations. Total WBC count was found to be significantly (P < 0.05) higher in T(1 )relative to all other treatments. Serum albumin and A/G ratio was found to be significantly lower in fish of T(1) and T(2) in relation to T(7) group (P < 0.05). Serum globulin and total protein levels remained unaffected by variations in dietary phosphorus. HSP70 expression was observed in T(1) group (0.1% dP) in gills and brain tissue, but not in liver and muscle tissues. No HSP70 expression was observed in fish of T(4) (0.7% dP) and T(8) (1.5% dP) treatments. These prima facie results suggest that dietary phosphorus had only minor influence on the haemato-biochemical parameters studied; however dietary phosphorus deficiency caused organ specific induction of HSP70 in catla fingerlings.

Aspectos atuais da relação entre exercício físico, estresse oxidativo e magnésio

Este trabalho visa a contribuir com informações atualizadas sobre a relação entre exercício, estresse oxidativo e magnésio. São escassos os trabalhos que discutem a produção de radicais livres nesse contexto. A deficiência de magnésio altera a fluidez das membranas celulares e mitocondriais e promove perturbações na homeostase do cálcio e na atividade das defesas antioxidantes. No exercício, a falta de magnésio nos tecidos musculares os torna mais suscetíveis à infiltração de macrófagos e neutrófilos e ao rompimento do sarcolema, dificultando o processo de regeneração e podendo ocasionar queda no desempenho físico. Conclui-se que o papel metabólico da deficiência de magnésio no estresse oxidativo induzido pelo exercício deve ser mais pesquisado, focalizando os seus efeitos na musculatura esquelética em indivíduos que praticam exercício regular e na deficiência marginal de magnésio.

Inhibition of neutral endopeptidase potentiates neutrophil activation during Mg-deficiency in the rat

Neutral endopeptidase (NEP), which degrades substance P (SP), may regulate neutrophil activation during Mg-deficiency (MgD). Male Sprague-Dawley rats (180g) were fed MgD (approximately 50 mg Mg/kg) or Mg-sufficient (MgS, 608 mg Mg/kg) diets for 7 days +/- NEP inhibitor phosphoramidon (PR, 5 mg/kg/day, s.c.). MgD alone induced a 9-fold (vs. MgS, p <0.01) elevation in plasma SP; MgD+PR enhanced it further to 18-fold (p <0.001). Neutrophils from MgD+PR rats displayed a 3.9-fold higher (p <0.01) basal .O(2-) generation, but those from MgD or PR alone were not activated. Plasma PGE2-metabolite levels rose 2.67- (p <0.01) and 1.56- (p <0.05) fold, respectively, in MgD+PR and MgD groups; the corresponding red blood cell glutathione levels were decreased 21% (p <0.025) and 7% (NS). MgD+PR significantly reduced neutrophil NEP activity by 48% (p <0.02); PR or MgD alone only reduced this activity 26% and 15%, respectively. We conclude that NEP inhibition potentiates SP-mediated neutrophil .O(2-) production and may promote other inflammatory activities during MgD.