Brain lesions in newborns exposed to high-dose magnesium sulfate during preterm labor

Effects of MgSO4 Alone or Associated with 4-PBA on Behavior and White Matter Integrity in a Mouse Model of Cerebral Palsy: A Sex- and Time-Dependent Study

Cerebral palsy (CP) is defined as permanent disorders of movement and posture. Prematurity and hypoxia-ischemia (HI) are risk factors of CP, and boys display a greater vulnerability to develop CP. Magnesium sulfate (MgSO₄) is administered to mothers at risk of preterm delivery as a neuroprotective agent. However, its effectiveness is only partial at long term. To prolong MgSO₄ effects, it was combined with 4-phenylbutyrate (4-PBA). A mouse model of neonatal HI, generating lesions similar to those reported in preterms, was realized. At short term, at the behavioral and cellular levels, and in both sexes, the MgSO₄/4-PBA association did not alter the total prevention induced by MgSO₄ alone. At long term, the association extended the MgSO₄ preventive effects on HI-induced motor and cognitive deficits. This might be sustained by the promotion of oligodendrocyte precursor differentiation after HI at short term, which led to improvement of white matter integrity at long term. Interestingly, at long term, at a behavioral level, sex-dependent responses to HI were observed. This might partly be explained by early sex-dependent pathological processes that occur after HI. Indeed, at short term, apoptosis through mitochondrial pathways seemed to be activated in females but not in males, and only the MgSO₄/4-PBA association seemed to counter this apoptotic process.

Maternal magnesium sulfate administration increases early-onset hyperkalemia risk in premature infants: A propensity score-matched, case-control study

BACKGROUND

Magnesium sulfate (MgSO₄) is a common substance administered to pregnant women with preeclampsia or eclampsia to prevent and treat seizures or gestational hypertension. This study aimed to evaluate whether administering maternal magnesium sulfate increased the risk of early-onset hyperkalemia in preterm infants.

METHODS

This single-center, propensity score-matched, case-control study examined preterm infants born within 24-36 weeks of gestation using electronic medical records between January 2015 and June 2019, in the Saitama City Hospital, Japan. We categorized infants according to their maternal MgSO₄ administration status. After adjusting for perinatal information and maternal treatment, we compared the incidence of the variables, including neonatal hyperkalemia, within 24 h after birth between the matched cohorts. All infants in Model 1 were analyzed separately, while in Model 2 infants with birth weight of less than 1000 g were excluded.

RESULTS

We enrolled 421 infants (maternal MgSO4 group, 124; control group, 297). Ninety-five infants in Model 1 and 86 in Model 2 were matched in each group using propensity scores, respectively. In the matched cohorts of both models, infants in the maternal MgSO₄ group had a higher hyperkalemia incidence than did those in the control group (42.1% vs. 7.4% in Model 1, 44.2% vs. 5.8% in Model 2, respectively; p < 0.0001). However, there was no relationship between the duration of intrauterine exposure to MgSO₄ and early-onset neonatal hyperkalemia incidence.

CONCLUSION

Our study demonstrated that maternal MgSO₄ administration, even for a short period of time, may increase the risk of early-onset hyperkalemia in preterm infants. Accordingly, physicians should be cautious when administering serum potassium to infants born to mothers administered MgSO₄, especially within 24 h after birth.

Neonatal magnesium levels are safe after maternal MgSO(4) administration: a comparison between unexposed preterm neonates and neonates exposed for fetal neuroprotection or maternal eclampsia prevention-a cohort study

To objective of this study was to compare neonatal magnesemia in the first 15 days of neonatal life between three groups: a control group not exposed to MgSO₄, a neuroprotection group, and an eclampsia prevention group, and to explore its associations with child outcomes. A retrospective single-centre cohort study was performed in a tertiary care setting. Infants admitted at the neonatal intensive care unit born between 24 and 32 weeks' gestation, regardless of etiology of preterm birth, were included. The mean outcome measure was neonatal magnesemia (mmol/L). Linear mixed regression of neonatal magnesemia on exposure group and day of life was done. Generalised estimating equation models of child outcomes on neonatal magnesemia according to exposure group and day of life were made. The analyses showed that in neonatal magnesemia is significantly higher in the preeclampsia group compared to the control and neuroprotection groups. On the day of birth, this is irrespective of maternal magnesemia (preeclampsia vs control groups), and the maternal total dose or duration of MgSO₄ administration (preeclampsia vs neuroprotection group). No differences were found in short-term composite outcome between the three groups.

CONCLUSION

We found mean differences in neonatal magnesemia between children not exposed to MgSO₄ antenatally, children exposed for fetal neuroprotection, and children exposed for maternal eclampsia prevention. A 4-g loading and 1-g/h maintenance doses, for fetal neuroprotection and eclampsia prevention, appear to be safe on the short term for the neonate.

WHAT IS KNOWN

• Magnesium sulphate is a valuable medicine in obstetrics. The main indications are prevention of eclampsia and fetal neuroprotection. The most used dosage is a 4- or 6-g loading dose and a 1- or 2-g per h maintenance dose. It reduces neuromotor disabilities in extreme-to-moderate preterm born children.

WHAT IS NEW

• Maternal concentrations are supraphysiological and the maternal total dose can be high. Concentrations in neonates appear to remain in safe ranges. A dosage of 4-g loading and 1 g/h seems safe for the preterm neonate on the short term.

Effect of Neuroprotective Magnesium Sulfate Treatment on Brain Transcription Response to Hypoxia Ischemia in Neonate Mice

MgSO₄ is widely used in the prevention of preterm neurological disabilities but its modes of action remain poorly established. We used a co-hybridization approach using the transcriptome in 5-day old mice treated with a single dose of MgSO₄ (600 mg/kg), and/or exposed to hypoxia-ischemia (HI). The transcription of hundreds of genes was altered in all the groups. MgSO₄ mainly produced repressions culminating 6 h after injection. Bio-statistical analysis revealed the repression of synaptogenesis and axonal development. The putative targets of MgSO₄ were Mnk1 and Frm1. A behavioral study of adults did not detect lasting effects of neonatal MgSO₄ and precluded NMDA-receptor-mediated side effects. The effects of MgSO₄ plus HI exceeded the sum of the effects of separate treatments. MgSO₄ prior to HI reduced inflammation and the innate immune response probably as a result of cytokine inhibition (Ccl2, Ifng, interleukins). Conversely, MgSO₄ had little effect on HI-induced transcription by RNA-polymerase II. De novo MgSO₄-HI affected mitochondrial function through the repression of genes of oxidative phosphorylation and many NAD-dehydrogenases. It also likely reduced protein translation by the repression of many ribosomal proteins, essentially located in synapses. All these effects appeared under the putative regulatory MgSO₄ induction of the mTORC2 Rictor coding gene. Lasting effects through Sirt1 and Frm1 could account for this epigenetic footprint.

The effects of maternal body mass index and plurality on maternal and umbilical cord serum magnesium levels in preterm birth at less than 32 weeks of gestation

OBJECTIVE

To evaluate the effects of maternal body mass index (BMI) and plurality on maternal and umbilical cord serum magnesium levels after antenatal magnesium sulfate treatment.

METHODS

This was a retrospective cohort analysis of 135 women treated with antenatal magnesium sulfate at less than 32 weeks of gestation between January 2012 and June 2018. Subjects were stratified into groups according to maternal BMI (group I [18.5-22.9 kg/m²], group II [23.0-24.9 kg/m²], and group III [≥25.0 kg/m²]) and plurality (singleton and twin). Univariable and multivariable analyses were performed to compare the umbilical cord serum magnesium levels between the groups.

RESULTS

Maternal serum magnesium levels were not significantly different between the maternal BMI groups and singleton and twin pregnancies. Umbilical cord serum magnesium levels were significantly different among the maternal BMI groups (3.3±1.2 mg/dL in group I, 3.3±1.2 mg/dL in group II, and 4.0±1.4 mg/dL in group III, P=0.003). The trend of increase in magnesium levels was statistically significant (P=0.001, Jonckheere-Terpstra test). Umbilical cord serum magnesium levels were not significantly different according to plurality. However, in the multivariable analysis, maternal BMI and plurality were not significantly associated with umbilical cord serum magnesium levels after adjusting for indication and total dose of magnesium sulfate treatment, gestational age at delivery, mode of delivery, neonatal sex, and birth weight.

CONCLUSION

Maternal BMI and plurality were not significantly associated with maternal or umbilical cord serum magnesium levels after exposure to antenatal magnesium sulfate treatment.

The effect of antenatal magnesium sulfate on intraventricular hemorrhage in premature infants: a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis study was to determine the pooled estimate of the effect of antenatal magnesium sulfate (MgSO4) on intraventricular hemorrhage (IVH) in premature infants.

METHODS

Two review authors independently searched all randomized clinical trials from international databases, including Medline (PubMed), Web of Sciences, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and Research Registers of ongoing trials (ClinicalTrials.gov), from January 1989 to August 2017. Two independent review authors were responsible for data collection. After extracting the necessary information from the evaluated articles, metaanalysis of the data was performed using Stata version 14. Also, sources of heterogeneity among studies were determined by Meta regression.

RESULTS

In this study, among 126 articles that were extracted from primary studies, 7 papers that evaluated the effect of MgSO4 on IVH were eligible for inclusion in the meta-analysis. The results of the meta-analysis showed that pooled relative risk (95% confidence interval [CI]) was 0.80 (95% CI, 0.63 to 1.03) for the effect of MgSO4 on IVH.

CONCLUSION

RESULTS

of this study showed that although MgSO4 had a protective effect on IVH in premature infants, this effect was not statistically significant. Further studies are needed to determine the best dosage, timing, and gestational age to achieve the optimum effect of MgSO4 on IVH.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) Identifier: CRD42019119610.

Antenatal Magnesium Sulfate and Preeclampsia Differentially Affect Neonatal Cerebral Oxygenation

INTRODUCTION

Magnesium sulfate (MgSO4) is frequently administered for maternal and fetal neuroprotection in preeclampsia (PE) and imminent preterm birth, respectively.

OBJECTIVE

To assess whether MgSO4 affects neonatal cerebral oxygenation, blood flow, and cerebral autoregulation (CAR) during the first postnatal days independently from PE.

METHODS

148 neonates <32 weeks gestational age were included. Cerebral fractional tissue oxygen extraction (cFTOE) was extracted from a daily 2-h period, during which peak systolic blood flow velocity (PSV) and resistance index (RI) of the pericallosal artery were obtained. The percent time of impaired CAR (correlation coefficient between mean arterial blood pressure and cerebral oxygen saturation >0.5) was determined. Linear mixed models were applied.

RESULTS

MgSO4 exposure was recorded in 77 neonates. Twenty-nine neonates were born following PE. MgSO4 independently lowered cFTOE (B: -0.026, 95% CI: -0.050 to 0.002, p < 0.05) but did not affect PSV and RI. PE was associated with a lower cFTOE (B: -0.041, 95% CI: -0.067 to -0.015, p < 0.05) and a tendency towards both lower PSV (B: -4.285, 95% CI: -9.067 to 0.497, p < 0.1) and more impaired CAR (B: 4.042, 95% CI: -0.028 to 8.112, p < 0.1), which seemed to be strongly mediated by fetal brain sparing. MgSO4 did not alter CAR.

CONCLUSIONS

In contrast to fetal brain sparing in PE, MgSO4 seems to lower cFTOE by lowering cerebral oxygen demands in preterm neonates without affecting the cerebrovasculature.

Impact of dosing schedule on uptake of neuroprotective magnesium sulfate

Background: Preterm delivery <32-week gestation is associated with significant neurodevelopmental morbidity ranging from mild delay to profound disability. Several randomized trials have shown that magnesium sulfate (MgSO₄) is an effective neuroprotectant, demonstrating reduced rates of cerebral palsy, death, and gross motor dysfunction for the neonate or infant. Dosing was not consistent among the major trials and the onus was placed on institutions by ACOG to develop and implement protocols with respect to MgSO₄ as a neuroprotectant. A recent study demonstrated that MgSO₄ exposure <12 h prior to delivery was associated with a decrease in CP compared to more remote exposure.Objective: To assess impact of dosing schedule on uptake of neuroprotective MgSO₄ in patients delivering <32 weeks gestational age.Study design: A retrospective cohort study of all deliveries occurring <32 weeks' gestation at a single academic center between March-December 2014 and March-December 2015 was conducted. Institutional policy shifted in 2015 from MgSO₄ bolus with continuous infusion based on the BEAM trial to a single bolus dose based on the PREMAG trial. Patients with preeclampsia, known fetal anomalies, and/or stillbirth were excluded from this analysis. Patients were identified through query of the Medical University of South Carolina Perinatal Information System (PINS) database with respect to whether or not they had received MgSO₄ within 12 h of delivery. Chi-squared analysis was performed to compare the overall rate of MgSO₄ exposure and MgSO₄ exposure <12 h prior to delivery between groups. Fisher's exact test was used to evaluate maternal, obstetric, and neonatal variables among those receiving MgSO₄ within 12 h of delivery in each cohort. Binary logistic regression analysis was performed to control for co-linear or potential confounding variables.Results: A total of 224 patients were identified, 115 delivered between March-December 2014 and 109 delivered between March-December 2015. With respect to MgSO₄ exposure prior to delivery, 27 (23.5%) received MgSO₄ in the 2014 cohort compared to 44 (40.4%) in the 2015 cohort (OR: 2.2, p < .01). Of those being exposed within 12 h of delivery, there were 16 (13.9%) maternal exposures in the 2014 cohort versus 28 (26.7%) in the 2015 cohort (OR: 2.15, p = .02). Of the 18 neonates delivered in 2014 there were four cases of grade III or IV intraventricular hemorrhage versus one case among the 36 neonates (2.7%) born in 2015 (0.04). This finding holds after controlling for race, preterm labor, gestational age, corticosteroid, birthweight, and indomethacin exposure.Conclusions: Dosing of neuroprotective MgSO₄ according to PREMAG trial specifications was associated with a significantly greater percentage of patients having received neuroprotective magnesium at any point prior to delivery or within the 12 h prior to delivery when compared to dosing according to BEAM trial specifications.

Fetal Neuroprotection by Magnesium Sulfate: From Translational Research to Clinical Application

Despite improvements in perinatal care, preterm birth still occurs regularly and the associated brain injury and adverse neurological outcomes remain a persistent challenge. Antenatal magnesium sulfate administration is an intervention with demonstrated neuroprotective effects for preterm births before 32 weeks of gestation (WG). Owing to its biological properties, including its action as an N-methyl-d-aspartate receptor blocker and its anti-inflammatory effects, magnesium is a good candidate for neuroprotection. In hypoxia models, including hypoxia-ischemia, inflammation, and excitotoxicity in various species (mice, rats, pigs), magnesium sulfate preconditioning decreased the induced lesions’ sizes and inflammatory cytokine levels, prevented cell death, and improved long-term behavior. In humans, some observational studies have demonstrated reduced risks of cerebral palsy after antenatal magnesium sulfate therapy. Meta-analyses of five randomized controlled trials using magnesium sulfate as a neuroprotectant showed amelioration of cerebral palsy at 2 years. A meta-analysis of individual participant data from these trials showed an equally strong decrease in cerebral palsy and the combined risk of fetal/infant death and cerebral palsy at 2 years. The benefit remained similar regardless of gestational age, cause of prematurity, and total dose received. These data support the use of a minimal dose (e.g., 4 g loading dose ± 1 g/h maintenance dose over 12 h) to avoid potential deleterious effects. Antenatal magnesium sulfate is now recommended by the World Health Organization and many pediatric and obstetrical societies, and it is requisite to maximize its administration among women at risk of preterm delivery before 32 WG.

Experimental and clinical evidence of differential effects of magnesium sulfate on neuroprotection and angiogenesis in the fetal brain

Clinical studies showed beneficial effects of magnesium sulfate regarding the risk of cerebral palsy. However, regimen protocols fluctuate worldwide and risks of adverse effects impacting the vascular system have been reported for human neonates, keeping open the question of the optimal dosing. Using clinically relevant concentrations and doses of magnesium sulfate, experiments consisted of characterizing, respectively, ex vivo and in vivo, the effects of magnesium sulfate on the nervous and vascular systems of mouse neonates by targeting neuroprotection, angiogenesis, and hemodynamic factors and in measuring, in human fetuses, the impact of a 4‐g neuroprotective loading dose of magnesium sulfate on brain hemodynamic parameters. Preclinical experiments using cultured cortical slices from mouse neonates showed that the lowest and highest tested concentrations of magnesium sulfate were equally potent to prevent excitotoxic‐induced cell death, cell edema, cell burst, and intracellular calcium increase, whereas no side effects were found regarding apoptosis. In contrast, in vivo data revealed that magnesium sulfate exerted dose‐dependent vascular effects on the fetal brain. In particular, it induced brain hypoperfusion, stabilization of Hif‐1α, long‐term upregulation of VEGF‐R2 expression, impaired endothelial viability, and altered cortical angiogenesis. Clinically, in contrast to 6‐g loading doses used in some protocols, a 4‐g bolus of magnesium sulfate did not altered fetal brain hemodynamic parameters. In conclusion, these data provide the first mechanistic evidence of double‐sword and dose‐dependent actions of magnesium sulfate on nervous and vascular systems. They strongly support the clinical use of neuroprotection protocols validated for the lowest (4‐g) loading dose of magnesium sulfate.

Pharmacokinetics and placental transfer of magnesium sulfate in pregnant women

BACKGROUND

Magnesium sulfate is one of the most commonly prescribed intravenous medications in obstetrics. Despite its widespread use, there are limited data about magnesium pharmacokinetics, and magnesium is prescribed empirically without dose adjustment for different indications.

OBJECTIVE

The aim of this study was to characterize the pharmacokinetics and placental transfer of magnesium sulfate in pregnant women and to determine key covariates that impact the pharmacokinetics.

STUDY DESIGN

This is a prospective pharmacokinetic cohort study of pregnant women who were prescribed magnesium sulfate for preeclampsia, preterm labor, or extreme prematurity. Women received a 4-g loading dose and 2 g/h maintenance dose as clinically indicated. Maternal blood samples were obtained before and at multiple time points during and after magnesium administration. Cord blood also was sampled at delivery. A population pharmacokinetic approach that used a nonlinear mixed-effects modeling was used to characterize magnesium disposition.

RESULTS

Pharmacokinetic profiles of 111 pregnant women were analyzed. Magnesium clearance was 3.98 L/h in preeclamptic women and 5.88 L/h non-preeclamptic women. Steady-state concentration of magnesium was 7.2 mg/dL in preeclamptic women compared with 5.1 mg/dL in non-preeclamptic women. Maternal weight significantly impacted time to steady state. The ratio of the mean umbilical vein magnesium level to the mean maternal serum magnesium level at the time of delivery was 0.94 ± 0.15.

CONCLUSIONS

The study accurately characterizes the pharmacokinetics of magnesium administered to pregnant women. Preeclamptic status and maternal weight significantly impact serum magnesium levels. This pharmacokinetic model could be applied to larger cohorts to help tailor magnesium treatment and account for these covariates.

Short-term morbidities and neurodevelopmental outcomes in preterm infants exposed to magnesium sulphate treatment

AIM

The aim of the study is to examine whether baseline serum Mg concentration has an impact on short-term and long-term outcomes in preterm infants exposed antenatally to MgSO4.

METHODS

Participants included all infants admitted to the neonatal intensive care unit at <32 weeks of gestational age. Infant serum Mg concentration (iMgC) was examined immediately after birth in those exposed to maternal MgSO4. Data for short-term outcomes were collected from the infants' computerised charts. Neurodevelopmental outcomes at 6-12 months corrected age were assessed using the Griffiths Mental Developmental Scales.

RESULTS

Of 197 eligible infants, 145 were exposed to MgSO4. Baseline iMgC was available for 88 infants. Mean iMgC was 3.5 ± 0.88 mg/dL (1.6-5.7 mg/dL). Baseline iMgC was not associated with an increased risk for neither early morbidities nor adverse long-term outcome. However, iMgC above the mean (>3.5 mg/dL) was associated with significantly lower scores on locomotor (P = 0.016) and personal-social (0.041) scales in the first year of life.

CONCLUSIONS

In a cohort of preterm infants antenatally exposed to MgSO4, elevated baseline iMgC (>3.5 mg/dL) was associated with lower locomotor scores. Further research is needed in order to study the relationship between supra-physiologic iMgC and its effect on the developing brain.

Effects of antenatal magnesium sulfate treatment for neonatal neuro-protection on cerebral oxygen kinetics

BACKGROUND

The underlying neuro-protective mechanisms of antenatal magnesium sulfate (MgSO(4)) in infants born preterm remain poorly understood. Early neonatal brain injury may be preceded by low cerebral blood flow (CBF) and elevated cerebral fractional tissue oxygen extraction (cFTOE). This study investigated the effect of antenatal MgSO(4) on cerebral oxygen delivery, consumption, and cFTOE in preterm infants.

METHODS

CBF and tissue oxygenation index were measured, and oxygen delivery, consumption, and cFTOE calculated within 24 h of birth and at 48 and 72 h of life in 36 infants ≤ 30 wk gestation exposed to MgSO(4) and 29 unexposed infants.

RESULTS

Total internal carotid blood flow and cerebral oxygen delivery did not differ between the groups at the three study time-points. Cerebral oxygen consumption and cFTOE were lower in infants exposed to antenatal MgSO(4) (P = 0.012) compared to unexposed infants within 24 h of delivery. This difference was not evident by 48 h of age. Fewer infants in the MgSO(4) group developed P/IVH by 72 h of age (P = 0.03).

CONCLUSION

Infants exposed to MgSO(4) had similar systemic and cerebral hemodynamics but lower cFTOE compared to nonexposed. These findings suggest reduced cerebral metabolism maybe a component of the neuro-protective actions of antenatal MgSO(4).

Magnesium deposition in brain of pregnant patients administered intramuscular magnesium sulphate

We present three cases of T1 hyperintense signal in the MRI scans of the brains of pregnant patients who were administered magnesium sulphate intramuscularly for control of hypertension during eclampsia. The increase in signal is symmetric and is seen in the globus pallidi of these patients. We postulate it to be secondary to deposition of magnesium in the brain parenchyma. The signal intensity was found to be directly varying according to the level of magnesium in the blood. It decreased over a period of time coming to normalcy after approximately 6months. To the best of our knowledge, this is the first case report which has documented this finding. It has to be determined whether deposition of magnesium in the brain parenchyma could have implications in the use of magnesium sulphate in pregnant patients.

Baseline serum magnesium concentrations and neurodevelopmental outcomes of extremely low birth weight premature infants

AIM

To test the hypothesis that, in ELBW infants who did not receive antenatal MgSO4, lower baseline serum Mg is associated with poorer neurodevelopmental outcomes (NDO).

STUDY DESIGN

The study was conducted in two phases: phase 1-- retrospective, and phase 2--prospective.

SUBJECTS

Extremely low birth weight infants.

OUTCOME MEASURES

Mortality and adverse NDO were assessed in relation to initial serum Mg measured in the first 12 hours of age.

RESULTS

We studied 156 ELBW infants. In phase 1 (n=102): initial serum Mg (median [IQ range]) was greater in the infants who died compared to those who survived (1.7 [1.5-2.2] mg/dL vs. 1.6 [1.4-1.7] mg/dL, p=0.034). In phase 2 (n=54): initial serum Mg was greater in infants who died or had adverse NDO at 9 months when compared to those who survived with better NDO (1.7 [1.55-2.1] mg/dL vs. 1.5 [1.4-1.68] mg/dL, p=0.008). Using receiver operating characteristic (ROC) curve, increased Mg concentration in the first 12 hours>1.6 mg/dL was associated with unfavorable outcomes with sensitivity of 73%, specificity of 67%, and odds ratio of 5.5 (CI=1.2-24.8, p=0.037).

CONCLUSIONS

In a cohort of preterm infants without antenatal exposure to MgSO4, initial serum Mg concentrations associated positively with poor outcomes. Further studies are needed in ELBW infants with poor NDO to determine whether they have a dysfunctional transport system that prevents Mg from entering into cells, or they have an active process that excretes Mg extracellularly.

Neurotrophin-induced migration and neuronal differentiation of multipotent astrocytic stem cells in vitro

Hypoxic ischemic encephalopathy (HIE) affects 2-3 per 1000 full-term neonates. Up to 75% of newborns with severe HIE die or have severe neurological handicaps. Stem cell therapy offers the potential to replace HIE-damaged cells and enhances the autoregeneration process. Our laboratory implanted Multipotent Astrocytic Stem Cells (MASCs) into a neonatal rat model of hypoxia-ischemia (HI) and demonstrated that MASCs move to areas of injury in the cortex and hippocampus. However, only a small proportion of the implanted MASCs differentiated into neurons. MASCs injected into control pups did not move into the cortex or differentiate into neurons. We do not know the mechanism by which the MASCs moved from the site of injection to the injured cortex. We found neurotrophins present after the hypoxic-ischemic milieu and hypothesized that neurotrophins could enhance the migration and differentiation of MASCs. Using a Boyden chamber device, we demonstrated that neurotrophins potentiate the in vitro migration of stem cells. NGF, GDNF, BDNF and NT-3 increased stem cell migration when compared to a chemokinesis control. Also, MASCs had increased differentiation toward neuronal phenotypes when these neurotrophins were added to MASC culture tissue. Due to this finding, we believed neurotrophins could guide migration and differentiation of stem cell transplants after brain injury.

Serum magnesium in the first week of life in extremely low birth weight infants

BACKGROUND

Evidence that antenatal administration of magnesium sulfate (MgSO(4)) to women in preterm labor may confer fetal neuroprotection is growing. MgSO(4) crosses the placenta and can affect the neonate. Magnesium homeostasis in extremely low birth weight (ELBW) infants remains to be clarified.

OBJECTIVES

We aimed to assess the natural progression of serum magnesium (Mg) in ELBW infants not exposed to antenatal MgSO(4) during the first month of life.

METHODS

Laboratory data of a group of ELBW infants born in a tertiary center over a 1-year period were analyzed. Serum Mg was recorded daily for the first week and thereafter each week for a month for each infant. Concurrent calcium, phosphate and alkaline phosphatase were measured.

RESULTS

51 preterm infants (24 female) with a birth weight <1,000 g were included (33 were born at <27 weeks' gestation). The mean magnesium ranged from 0.9 to 1.1 mmol/l over the first week with a minimum of 0.62 mmol/l and maximum of 1.53 mmol/l. Mg rises in the first few days before stabilizing and remains within a narrow range thereafter.

CONCLUSIONS

In ELBW infants, Mg tends to rise initially then stabilize and remain normal thereafter. The effect of antenatal MgSO(4) on magnesium homeostasis requires further study.

Immediate clinical outcomes in preterm neonates receiving antenatal magnesium for neuroprotection

BACKGROUND

Antenatal magnesium sulfate can potentially reduce the risk of cerebral palsy in neonates delivered between 24 and 32 weeks of gestational age. Some studies using high-dose magnesium sulfate for neuroprotection have reported increased perinatal mortality.

METHODS

A retrospective study was conducted on 475 neonates born between 24 and 32 weeks of gestational age. Serum magnesium level in the first 24 h of life was used to stratify the neonates treated with antenatal magnesium into four subgroups: A (<2.5 mEq/L), B (≥2.5 to <3.5 mEq/L), C (≥3.5 to <4.5 mEq/L), and D (≥4.5 mEq/L). Primary outcome of survival without intraventricular hemorrhage (IVH) and/or periventricular leukomalacia (PVL) along with secondary outcomes, such as Apgar scores, resuscitation, intubation, broncho-pulmonary dysplasia, retinopathy of prematurity (ROP), patent ductus arteriosus (PDA), time to reach full feeds, length of stay (LOS), and mortality during immediate neonatal period were studied.

RESULTS

Of the 475 neonates included in the study, 289 (61%) received antenatal magnesium sulfate. Primary outcome of survival without IVH and/or PVL among the preterm neonates was 70.9% in those receiving and 74.2% in those not receiving antenatal magnesium (P=0.25). There were higher incidences of ROP (P=0.02), PDA (P=0.01), greater time to reach full feeds (P=0.03), and increased LOS (P=0.01) in neonates who had received antenatal magnesium. These findings were not statistically significant when the data were corrected for gestational age and birth weight. Among the subgroups, there was a significantly increased mortality rate (P<0.05) with increasing magnesium levels (5% vs. 16.9%, P<0.05 in groups A vs. D) and a trend toward higher intubation rate (P=0.1) and PDA (P=0.14).

CONCLUSION

Antenatal magnesium is safe in the immediate postnatal period; however, in the subset of preterm neonates with serum magnesium levels >4.5 mEq/L, there is increased mortality independent of birth weight and gestational age. Identification of these neonates and appropriate dosing for their antenatal neuroprotection needs to be studied.

Antenatal magnesium sulfate and the postnatal response of the ductus arteriosus to indomethacin in extremely preterm neonates

OBJECTIVE

The aim of this study is to evaluate the influence of antenatal magnesium sulfate (MgSO(4)) treatment on the clinical responsiveness of the ductus arteriosus to indomethacin prophylaxis and on that of symptomatic patent ductus arteriosus (sPDA) to indomethacin treatment in premature neonates.

STUDY DESIGN

This is a retrospective study of 160 consecutively admitted neonates with a gestational age of <28 weeks (41 MgSO(4) exposed and 119 controls) who received indomethacin prophylaxis.

RESULT

Incidence of early closure of the ductus arteriosus was lower in the MgSO(4)-exposed neonates than in the control group (59 vs 84%, respectively; P=0.002), whereas incidence of an sPDA was higher (46 vs 24%, respectively; P=0.006). Response to indomethacin treatment was similar between the two groups. Logistic regression analysis indicated increased risk of failure of early ductus arteriosus closure following antenatal MgSO(4) treatment (odds ratio, 4.03; P=0.002).

CONCLUSION

In extremely preterm neonates, antenatal MgSO(4) treatment reduces clinical responsiveness of the ductus arteriosus to indomethacin prophylaxis but not that of sPDA to indomethacin treatment.

Urine iodine levels in preeclamptic and normal pregnant women

The aim of this study was to investigate the urine iodine concentration in women with severe preeclampsia and in healthy women in Erzurum, Turkey. Urine specimens were obtained from 40 severe preeclampsia and 18 healthy pregnant women. Urinary iodine levels were determined by the Foss method based on the Sandell-Kolthoff reaction. The urinary iodine level for women with severe preeclampsia was 4.25 +/- 2.7 microg/dL, lower than 20.89 +/- 6.4 microg/dL of urinary iodine for healthy pregnant women (p < 0.001). Blood magnesium concentration was found to be 1.63 +/- 0.05 mg/dL for women with severe preeclampsia, which is lower than that of healthy pregnant women (1.87 +/- 0.05 mg/dL; p < 0.001). There was a positive correlation between urinary iodine level and blood magnesium level in pregnant women with preeclampsia (Pearson correlation coefficient = 0.43; p < 0.01). However, there was no correlation between urinary iodine level and blood magnesium level in healthy pregnant women. There was no difference in thyroid hormone levels (T4, TSH, FT4) between women with severe preeclampsia and healthy pregnant women. However, there was a difference in T3 thyroid hormone levels between women with severe preeclampsia (1.86 +/- 0.4 microg/dL) and healthy pregnant women (1.45 +/- 0.3 microg/dL; p < 0.001). There was also a difference in FT3 between women with severe preeclampsia (2.77 +/- 0.4 pg/mL) and healthy pregnant women (2.41 +/- 0.5 microg/dL; p < 0.01). Urinary iodine excretion is currently the most convenient laboratory marker of iodine deficiency. The method is useful for the rapid and low-cost assessment of iodine deficiency. Our results suggested that urinary iodine concentration might be a useful marker for prediagnosing preeclamptic women. In addition, iodine supplementation may also be considered for preeclamptic therapy.

Magnesium sulfate treatment alters fetal cerebellar gene expression responses to hypoxia

Prenatal perturbation of brain circulation and oxygenation is a leading cause of perinatal brain damage affecting about 0.3-0.9% of births. Hypoxia-ischemia (HI) in preterm human infants at gestational week 23-32 results in neurodevelopmental abnormalities in childhood, presenting as learning disability, seizure activity, motor impairment and in the most severe cases, death. Here, we examined the potential of MgSO4 treatment, prior to foetal hypoxia, to attenuate hypoxia induced damage in a murine model of maternal hypoxia. We studied the time course of maternal hypoxia and MgSO4 pre-treatment effects on cerebellar tissue by means of DNA microarray analyses. Mild hypoxia induced minor expression changes in most genes. However, there were 5 gene sets which were down-regulated by maternal hypoxia. MgSO4 pre-treatment abrogated these decreases in gene. A cell cycle gene set which responded immediately (2 h) to hypoxia, showed a delayed response (24 h) when MgSO4 pre-treatment was given. Similar proportions of cell death were observed in all groups before P7, where combined hypoxia and MgSO4 treatment increased cell death in the internal granule layer. There were a higher number of BrdU positive cells at the end of hypoxic episodes and a down-regulation of Reelin signaling, compared to control. MgSO4 pre-treatment prevented the enhancement of cell proliferation due to hypoxia and increased Reelin levels. Altogether, MgSO4 pre-treatment both reduced the number of genes differentially affected by hypoxia and delayed the responses to hypoxia. In addition, MgSO4 pre-treatment modified the nature of the transcriptional response; while hypoxia induced down-regulation of gene sets, MgSO4 pre-treatment mostly up-regulated them. The dual reaction to the MgSO4 treatment may be the source of the ambiguity in observations reported for affected newborns.

High dose magnesium sulfate exposure induces apoptotic cell death in the developing neonatal mouse brain

BACKGROUND

Magnesium sulfate (MgSO4) is often used as a treatment for pre-eclampsia/eclampsia and preterm labor, resulting in the exposure of a significant number of neonates to this drug despite a lack of evidence suggesting that it is safe, or effective as a tocolytic. While there is evidence that MgSO4 may be neuroprotective in perinatal brain injury, recent reviews have suggested that the effects are dependent upon dose, and that higher doses may actually increase neonatal morbidity and mortality. There is a lack of evidence investigating the neurotoxic effects of neonatal magnesium (Mg) exposure on the developing brain, specifically in terms of neurodevelopmental apoptosis, a cell-killing phenomenon known to be potentiated by other drugs with mechanisms of action at Mg-binding sites (i.e. NMDA receptor antagonists such as MK-801, ketamine, and PCP).

OBJECTIVE

To investigate the effects of Mg exposure on the neonatal mouse brain at different postnatal ages to determine whether MgSO4 treatment causes significant cell death in the developing mouse brain.

METHODS

C57Bl/6 mice were treated with four doses of MgSO4 (250 mg/kg) on postnatal days 3 (P3), 7 (P7) or 14 (P14). Caspase-3 immunohistochemistry, cupric silver staining, and electron microscopy techniques were used to examine Mg-treated brains for neurotoxic effects.

RESULTS

Qualitative evaluation using cupric silver staining revealed widespread damage throughout the brain in P7 animals. Results of electron microscopy confirmed that the cell death process was apoptotic in nature. Quantitative evaluation of damage to the cortex, caudate-putamen, hippocampus, thalamus, and cerebellum showed that Mg treatment caused significant brain damage in animals treated on P3 and P7, but not P14.

CONCLUSIONS

Administration of high doses of Mg may be detrimental to the fetal brain, particularly if exposure occurs during critical periods of neurodevelopment.

Iodine and magnesium levels in maternal and umbilical cord blood of preeclamptic and normal pregnant women

The objective of this study was to investigate the relationship between preeclampsia and iodine levels and magnesium concentration in the blood of subjects in the northeast Anatolia region where iodine deficiency is common. Blood specimens were obtained from 24 preeclamptic and 16 healthy pregnant women. Iodine levels in blood were determined by the Foss method based on the Sandell-Kolthoff reaction. Serum protein-bound iodine (PBI) levels and magnesium concentration in maternal blood were lower in patients with severe preeclampsia compared to normal pregnant women (8.46 +/- 1.22 vs. 11.46 +/- 1.71 microg/dL, p < 0.001, 1.63 +/- 0.05 vs. 1.86 +/- 0.05 mg/dL, p < 0.001, respectively). Serum PBI levels and magnesium concentration in umbilical cord blood were higher in patients with severe preeclampsia than in normal pregnant women (8.84 +/- 1.9 vs. 7.33 +/- 1.07 microg/dL, p < 0.05, 2.48 +/- 0.03 vs. 2.02 +/- 0.01 mg/dL, p < 0.001, respectively). There was a positive correlation between the serum PBI levels in maternal blood and magnesium concentration in maternal blood in patients with severe preeclampsia (r = 0.41, p < 0.05). Thus, iodine may be one factor contributing to the pathophysiology of preeclampsia. Iodine supplementation may be effective therapy in preeclamptic in pregnant women.

Anti-inflammatory and immunomodulatory strategies to protect the perinatal brain

Infection and inflammation contribute to perinatal brain damage, particularly to the white matter. Although combating perinatal inflammation can be dangerous, because inflammation might have beneficial effects for mother and fetus, it is worthwhile reviewing potential anti-inflammatory neuroprotective compounds, along with their potential adverse effects. Further research on the possible neuroprotective roles of existing medications and substances is necessary.

Placental tissue iodine level and blood magnesium concentration in pre-eclamptic and normal pregnancy

OBJECTIVE

To assess iodine concentration in the placental tissue and magnesium concentration in the blood of women with severe pre-eclampsia in northeast Anatolia and compare these values with those of healthy pregnant women from the same region.

METHODS

Placental tissue and blood specimens were obtained from 20 severely pre-eclamptic and 15 healthy pregnant women. Iodine levels in placental tissue were determined by the Foss method based on the Sandell-Kolthoff reaction.

RESULTS

Placental tissue iodine levels were lower in women with severe pre-eclampsia than in healthy pregnant women (4.30+/-1.36 ng of iodine/mg protein vs. 7.71+/-2.84 ng of iodine/mg tissue protein; P<0.001), as were blood magnesium levels (1.63+/-0.05 mg/dL vs. 1.87+/-0.05 mg/dL; P<0.001). There was a positive correlation between placental tissue iodine levels and blood magnesium levels in women with severe pre-eclampsia (r=0.55, P<0.05), but no such correlation was observed in healthy pregnant women (r=0.23, P=0.41).

CONCLUSION

Magnesium assimilation is known to be defective when iodine levels are insufficient. In northeast Anatolia, where iodine deficiency is common, clinical trials of iodine supplementation should be considered for pre-eclamptic therapy.

Magnesium sulfate suppresses inflammatory responses by human umbilical vein endothelial cells (HuVECs) through the NFkappaB pathway

Dysfunctional endothelial cell activation and cytokines are implicated in preterm labor, a condition commonly treated with the tocolytic agent, magnesium sulfate (MgSO(4)). Based on recent findings showing the inflammatory effects of magnesium deficiency, we examined the effect of MgSO(4) on human umbilical vein endothelial cell (HuVEC) inflammatory responses in vitro. HuVECs isolated from term umbilical cords were incubated with MgSO(4) prior to stimulation with lipopolysaccharide (LPS) and then assessed for endothelial cell activation. Endothelial cell supernatants were assayed for inflammatory mediator production (interleukin-8; IL-8), and endothelial cell-associated intercellular adhesion molecule (ICAM-1) expression was determined. In the absence of LPS stimulation, MgSO(4) had no effect on HuVEC responses. Treatment of HuVECs with MgSO(4) prior to LPS stimulation inhibited inflammatory mediator production (p<0.05) and cell adhesion molecule expression (p<0.05) in a dose-dependent manner. Mechanistic studies showed that MgSO(4) reduced NFkappaB nuclear translocation and protected cytoplasmic IkappaBalpha from degradation in LPS-treated HuVECs. In conclusion, MgSO(4) inhibits endothelial cell activation, as measured by levels of IL-8 and ICAM-1 expression, via NFkappaB. Our results support the hypothesis that MgSO(4) treatment may function as an anti-inflammatory agent during preterm labor.