Measurement of free magnesium in blood, serum and plasma with an ion-sensitive electrode

Serum Mg Isotopic Composition Reveals That Mg Dyshomeostasis Remains in Type 1 Diabetes despite the Resolution of Hypomagnesemia

Hypomagnesemia was historically prevalent in individuals with type 1 diabetes mellitus (T1DM), but contemporary results indicate an incidence comparable to that in the general population, likely due to improved treatment in recent decades, resulting in better glycemic control. However, a recent study found a significant difference between the serum Mg isotopic composition of T1DM individuals and controls, indicating that disruptions to Mg homeostasis persist. Significant deviations were also found in samples taken one year apart. To investigate whether the temporal variability in serum Mg isotopic composition is linked to the transient impact of administered insulin, Mg isotope ratios were determined in serum from 15 T1DM individuals before and one hour after insulin injection/meal consumption using multi-collector inductively coupled plasma-mass spectrometry. Consistent with results of the previous study, significant difference in the serum Mg isotopic composition was found between T1DM individuals and 10 sex-matched controls. However, the average difference between pre- and post-insulin injection/meal T1DM samples of 0.05 ± 0.13‱ (1SD) was not significant. No difference was observed for controls before (-0.12 ± 0.16‱) and after the meal (-0.10 ± 0.13‱) either, suggesting a lack of a postprandial Mg isotopic response within one hour of food consumption, and that the timing of the most recent meal may not require controlling for when determining serum Mg isotopic composition.

Aflatoxicosis in cattle: clinical findings and biochemical alterations

Aflatoxicosis is a serious health condition resulted from aflatoxin (AF)-producing fungi. Major health threats resulted from AFs and reflect on the livestock industry with great economic losses. There are limited scientific evidences concerning the AFs in ruminant, therefore it is important to evaluate AFs health hazards in cattle. Here, we investigate biochemical, oxidative stress, and postmortem changes associated with unexpected acute bovine aflatoxicosis. Seventy-two cattle were suffered from aflatoxisocis. Depression and inappetence were predominant clinical findings of the diseased animals. Analysis of feedstuffs revealed presence of aflatoxin B1 (AFB1). The AF-intoxicated animals showed a significant increase in alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), serum creatinine (SCr), catalase (CAT), and malondialdehyde (MDA) levels. Moreover, a significant decrease in total protein (TP), magnesium (Mg), and reduced glutathione (GSH) were also seen. Hepatomegaly, enlarged gallbladder as well as congestion of the intestine and kidney were observed. This study elucidates the critical and constructive measurements needed for the prevention of the AFs hazardous effects to livestock for the future control of AF outbreaks. Conducting series of diagnostic assays reflect the marked health condition alterations in the biochemical and antioxidant status of the AF-intoxicated cattle.

Neutrophil extracellular trap fragments stimulate innate immune responses that prevent lung transplant tolerance

Neutrophil extracellular traps (NETs) have been shown to worsen acute pulmonary injury including after lung transplantation. The breakdown of NETs by DNAse-1 can help restore lung function, but whether there is an impact on allograft tolerance remains less clear. Using intravital 2-photon microscopy, we analyzed the effects of DNAse-1 on NETs in mouse orthotopic lung allografts damaged by ischemia-reperfusion injury. Although DNAse-1 treatment rapidly degrades intragraft NETs, the consequential release of NET fragments induces prolonged interactions between infiltrating CD4⁺ T cells and donor-derived antigen presenting cells. DNAse-1 generated NET fragments also promote human alveolar macrophage inflammatory cytokine production and prime dendritic cells for alloantigen-specific CD4⁺ T cell proliferation through activating toll-like receptor (TLR) - Myeloid Differentiation Primary Response 88 (MyD88) signaling pathways. Furthermore, and in contrast to allograft recipients with a deficiency in NET generation due to a neutrophil-specific ablation of Protein Arginine Deiminase 4 (PAD4), DNAse-1 administration to wild-type recipients promotes the recognition of allo- and self-antigens and prevents immunosuppression-mediated lung allograft acceptance through a MyD88-dependent pathway. Taken together, these data show that the rapid catalytic release of NET fragments promotes innate immune responses that prevent lung transplant tolerance.

Ionized and Total Magnesium Levels Change during Repeated Exercise in Older Adults

BACKGROUND

Magnesium is essential for health and performance. Sub-optimal levels have been reported for older persons. In addition, physical exercise is known to temporally decrease magnesium blood concentrations.

OBJECTIVE

To investigate these observations in conjunction we assessed total (tMg) and ionized magnesium (iMg) concentrations in plasma and whole blood, respectively, during 4 consecutive days of exercise in very old vital adults.

DESIGN

68 participants (age 83.7±1.9 years) were monitored on 4 consecutive days at which they walked 30-40km (average ~8 hours) per day at a self-determined pace. Blood samples were collected one or two days prior to the start of exercise (baseline) and every walking day immediately post-exercise. Samples were analysed for tMg and iMg levels.

RESULTS

Baseline tMg and iMg levels were 0.85±0.07 and 0.47±0.07 mmol/L, respectively. iMg decreased after the first walking day (-0.10±0.09 mmol/L, p<.001), increased after the second (+0.11±0.07 mmol/L, p<.001), was unchanged after the third and decreased on the final walking day, all compared to the previous day. tMg was only higher after the third walking day compared to the second walking day (p=.012). In 88% of the participants, iMg levels reached values considered to be sub-optimal at day 1, in 16% of the participants values were sub-optimal for tMg at day 2.

CONCLUSION

Prolonged moderate intensity exercise caused acute effects on iMg levels in a degree comparable to that after a bout of intensive exercise. These effects were not associated with drop-out or health problems. After the second consecutive day of exercise, levels were returned to baseline values, suggesting rapid adaptation/resilience in this population.

Total and ionized serum magnesium and calcium levels during magnesium sulfate administration for preterm labor

Objective

This study aimed to estimate the association between total and ionized magnesium, and the changes in serum magnesium and calcium levels in patients with preterm labor during magnesium sulfate (MgSO₄) administration.

Methods

The study population included 64 women who were candidates for intravenous MgSO₄ treatment for preterm labor. Serial blood samples were taken and measured total magnesium (T-Mg), ionized magnesium (I-Mg), total calcium (T-Ca), and ionized calcium (I-Ca) levels every one-week interval (1st, 2nd, 3rd).

Results

There was no significant difference in T-Mg and I-Mg levels during MgSO₄ administration (P>0.05). There was no significant difference in T-Ca and I-Ca levels during MgSO₄ administration (P>0.05). Compared before and after administration of MgSO₄, T-Mg and I-Mg levels and T-Ca levels were changed allow statistically significant (P<0.05). But, there was no significant difference in the I-Ca serum levels before and after MgSO₄ administration (P=0.495). The I-Mg levels for patients with adverse effect were higher than other group but did not reach statistical significance (P>0.05). There was significant correlation between levels of I-Mg and T-Mg (I-Mg=0.395×T-Mg+0.144, P<0.01).

Conclusion

There were no significant differences in serum Mg and Ca levels during MgSO₄ administration for preterm labor. Compared to the before and after administration of MgSO₄, only I-Ca levels were not substantially changed. There are significant correlations between I-Mg and T-Mg levels during administration of MgSO₄ and I-Mg level seemed to have more correlation with adverse effect than T-Mg.

Deficiency of calcium and magnesium induces apoptosis via scavenger receptor BI

AIMS

Cells undergo apoptosis in stressed status such as in intracellular calcium overload or extracellular calcium/magnesium deficiency. The mechanisms of how deficiency of the divalent metal ions induces apoptosis remain to be defined. Scavenger receptor BI (SR-BI) is a high density lipoprotein (HDL) receptor. Recent studies demonstrated that SR-BI is a stress response molecule which induces apoptosis upon serum deprivation. In this study, we assessed our hypothesis that the deficiency of calcium/magnesium induces apoptosis via SR-BI apoptotic pathway.

MAIN METHODS

We employed CHO cell lines expressing vector and SR-BI to test the effect of SR-BI on apoptosis induced by deficiency of calcium, magnesium and zinc in culture medium. The regain of different metal ions in deficient medium was also performed, respectively. Cell death was detected by morphological changes and quantified by LDH cytotoxicity assay. Apoptosis was also assessed by DNA ladder assay and DNA condensation assay. The SR-BIC323G mutant cells which lack the apoptotic activity of SR-BI were employed to verify the SR-BI-dependent effect on calcium/magnesium induced apoptosis.

KEY FINDINGS

The deficiency of calcium/magnesium induced cell apoptosis in CHO-SR-BI cells, but not in CHO-vector cells. Moreover, no apoptotic cell death was observed in SR-BIC323G mutant cells, indicating that the deficiency of divalent metal ions induces apoptosis in a SR-BI-dependent manner. Furthermore, the restoration of calcium or magnesium, but not zinc, protected CHO-SR-BI cells from apoptotic cell death, in a dose-dependent fashion.

SIGNIFICANCE

These findings extend our understanding about how calcium and magnesium deficiency induces apoptosis.

Metabolic and respiratory status of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii)

"Cold-stunning" of sea turtles has been reported as a naturally occurring stressor for many years; however, the physiologic status of cold-stunned turtles has only been partially described. This study investigated initial and convalescent venous blood gas, acid-base, and critical plasma biochemical data for 26 naturally cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) from Cape Cod, MA, USA. Samples were analyzed for pH, pCO(2), pO(2), bicarbonate, plasma osmolality, sodium, potassium, chloride, ionized calcium, ionized magnesium, glucose, lactate, and blood urea nitrogen using a clinical point-of-care analyzer. Data were corrected for the patient's body temperature using both species-specific and more general correction methods. In general, venous blood gas, acid-base, and plasma biochemical data obtained for surviving cold-stunned Kemp's ridley sea turtles were consistent with previously documented data for sea turtles exposed to a wide range of temperatures and physiologic stressors. Data indicated that turtles were initially affected by metabolic and respiratory acidosis. Initial pH-corrected ionized calcium concentrations were lower than convalescent concentrations, and initial pH-corrected ionized magnesium concentrations were higher than convalescent concentrations.

Variability within individuals of plasma ionic magnesium concentrations

BACKGROUND

With the invention of the ion-selective electrode (ISE), ionic magnesium (iMg) is a common blood assay. This could be advantageous, as iMg is the biologically active form of Mg. There is some evidence that iMg has considerable within subject variability.

RESULTS

Individual ranges averaged.08 mmol/L (range.05 to.14). Coefficients of variation (CV) ranged from 3% to 7% (mean 4%) while analytical variation was determined to be 2.3%. Biological variability thus accounts for almost half of the variability, which is clinically significant, as 9 of the 13 subjects recorded at least one value below a reference range of.46 -.60 mmol/L. A significant within-day variation (p <.001) was noted, with differences between 7:00 and 10:00 as well as 10:00 and 22:00. Between day variations were not significant (p =.56).

CONCLUSIONS

A plausible explanation of this data is that iMg has a circadian rhythm. Thus, cautious interpretation of single iMg values is warranted until future research determines the nature of iMg variability.