Neurodevelopmental outcome after extreme prematurity: a review of the literature

The Development of the Mother-Infant Mutualistic Screening Scale

BACKGROUND

The integrity of a mother-infant dyad is essential for the proper development of maternal behavior and infant growth/ development. At present, there is a lack of objective approaches to monitor mother-infant behavioral exchanges.

OBJECTIVES

This is an exploratory prospective study designed to evaluate the Mother-Infant Mutualistic Screening Scale (MIMSS), a novel observational tool focused on monitoring the mutual/ reciprocal sensitivity and responsiveness that mother and infant express toward one another's behaviors/ actions during the obligatory setting of daily meal times.

METHODS

Mother-infant interactions were assessed from videotaped feeding sessions conducted under recurrent naturalistic observations. Data were collected from 27 mother-preterm infant singleton dyads at 6 and 12 month corrected age (CA). Four levels of MIMSS are defined: Level I - both mother and infant are not responsive (NR) to one another's actions; Level II - mother is not responsive (NR) to infant, but infant is responsive (R) to mother; Level III - mother is responsive (R) to infant, but infant is not responsive (NR) to mother; Level IV - both mother and infant are responsive (R) to one another.

RESULTS

Inter- and intra-rater reliability between two raters was 93% and ≥ 85%, respectively. At 6 and 12 month CA, 78% and 81% of the dyads were at a MIMSS Level IV, respectively. A change in mother-infant reciprocal behavioral responses or MIMSS levels was observed in 9 of the dyads between these two ages. No association was observed between MIMSS levels and infant growth/ development as monitored by percentile Weight, Length, and Weight by Length at both corrected ages.

CONCLUSIONS

The MIMSS is easy to use with high inter- and intra-rater reliabilities. With the ability to differentiate between mother and infant reciprocal behavioral responses toward one another's actions, MIMSS can help health professionals assess the quality of mother-infant interactions and identify the partner(s) who may benefit from individualized assistance. Although MIMSS uses mealtime as a recurrent setting, it offers a conceptual frame work for evaluating co-regulatory processes under different contexts.

Incidental findings on routine brain MRI scans in preterm infants

OBJECTIVE

Many neonatal intensive care units (NICUs) have adopted the practice of performing routine brain MRI in very low birth weight (VLBW) infants at term-equivalent age in order to better evaluate prematurity-related acquired lesions. A number of unexpected brain abnormalities of potential clinical significance can be visualised on routine scans as well. The aim of our study was to describe these incidental findings (IFs) in a VLBW population and to assess their clinical significance.

STUDY DESIGN

We retrospectively reviewed a series of brain MRI scans performed in VLBW infants consecutively admitted to our NICU between November 2011 and November 2014. IFs on brain MRI, which were not detected by cranial ultrasound nor suspected clinically, were registered. Clinical significance of IF was assessed in terms of need of further diagnostic or therapeutic interventions.

RESULTS

IFs were detected in 28 out of 276 VLBW infants (10.1%). In total, 21 cases (7.6%) required an intervention, which was only diagnostic in 16 cases, and both diagnostic and therapeutic in 5 cases. In the remaining seven cases (2.5%), no further action was considered necessary.

CONCLUSIONS

This study suggests that IFs on brain MRI of VLBW infants are not rare. In our population, most of them required a diagnostic or therapeutic intervention. The need and appropriateness of routine MRI scanning in VLBW at term-equivalent age are still subject of debate, and we believe our data can contribute meaningfully to this discussion.

Does maternal psychological distress affect neurodevelopmental outcomes of preterm infants at a gestational age of ≤32weeks

BACKGROUND

There is some evidence that maternal psychological status in the prenatal and postnatal periods is associated with infants' cognitive, behavioural, and emotional functions.

AIM

The aim of this study was to examine the relationships of maternal depression and anxiety with neurodevelopmental outcomes of preterm infants with a gestational age of ≤32weeks, examined at a corrected age of 18 to 22months.

STUDY DESIGN

Cross-sectional study.

SUBJECTS

In total, 220 preterm infants with a gestational age of ≤32weeks who were born from January 2008 to September 2011 and admitted to the neonatal intensive care unit were prospectively examined.

OUTCOME MEASURES

Neurodevelopmental evaluation was performed at a corrected age of 18 to 22months by a developmental paediatrician using the Bayley Scales of Infant Development II (BSID-II). The Beck Depression Inventory and Beck Anxiety Inventory were used to assess maternal depression and anxiety at the same visit as the neurodevelopmental evaluation.

RESULTS

The depression scores of mothers of infants with a Mental Development Index (MDI) score of <70 were significantly higher than those of mothers of infants with an MDI score of >70 (16.3±12.8 vs 8.8±7.0, p<0.001). The depression scores of mothers of infants with neurodevelopmental impairment were also significantly higher than those without neurodevelopmental impairment (12.8±10.5 vs 8.8±7.3, p=0.003). There was no relationship between the presence of cerebral palsy or a Psychomotor Developmental Index (PDI) score of <70 and the mothers' depression scores. Multiple regression analysis revealed that maternal depression and the occurrence of more than two sepsis attacks were associated with an MDI score of <70, and grade III to IV intraventricular haemorrhage was associated with neurodevelopmental impairment and a PDI score of <70.

CONCLUSION

Maternal depression is negatively associated with the neurodevelopment of preterm infants at a gestational age of ≤32weeks. Maternal psychological well-being should be taken into consideration during the long-term follow-up of preterm infants.

NICU Human Milk Dose and 20-Month Neurodevelopmental Outcome in Very Low Birth Weight Infants

BACKGROUND

The association between human milk (HM) feeding in the NICU and neurodevelopmental (ND) outcome in very low birth weight (VLBW) infants is unclear. Limitations of previous studies include a lack of exact estimates of HM dose and of generalizability to minority populations.

OBJECTIVE

To determine the impact on ND outcome of an exact dose of HM received in the NICU in a diverse, contemporary cohort of VLBW infants.

METHODS

We included 430 VLBW infants born in the period 2008-2012 for whom the mean daily dose (DD) of HM received during the stay in the NICU (NICU HM-DD) was calculated prospectively from the daily nutritional intake from admission to discharge. Outcomes included Bayley-III index scores at 20 months' corrected age (CA) as assessed upon ND follow-up, which were collected retrospectively. Multivariable linear regression analyses controlled for neonatal and social risk factors.

RESULTS

Each 10 mL/kg/day increase in NICU HM-DD was associated with a 0.35 increase in cognitive index score (95% CI [0.03-0.66], p = 0.03), but no significant associations were detected for the language or motor indices.

CONCLUSIONS

There is a significant dose-dependent association between NICU HM intake and cognitive scores at 20 months' CA. Further follow-up will determine whether these findings persist at school age, and could help alleviate the special-education and health-care burden in this population.

Neurally Adjusted Ventilatory Assist in Preterm Infants With Established or Evolving Bronchopulmonary Dysplasia on High-Intensity Mechanical Ventilatory Support: A Single-Center Experience

OBJECTIVES

The aim of the present study was to report possible improvements in ventilator variables associated with a transition from synchronized intermittent mandatory ventilation to neurally adjusted ventilatory assist in preterm infants with bronchopulmonary dysplasia who required a high level of mechanical ventilatory support in a single center.

DESIGN

Retrospective study.

SETTING

Neonatal ICU.

PATIENTS

Twenty-nine preterm infants with a median gestational age of 25.4 weeks (range, 23.4-30.3 wk) and a median birth weight of 680 g (range, 370-1,230 g) and who were supported with a mechanical ventilator for more than 4 weeks and had a respiratory severity score greater than four during conventional mechanical ventilation prior to conversion to neurally adjusted ventilatory assist.

INTERVENTIONS

Comparison of ventilatory variables, work of breathing, and blood gas values during conventional ventilation and at various time intervals after the change to neurally adjusted ventilatory assist.

MEASUREMENTS AND MAIN RESULTS

The values of various ventilatory variables and other measurements were obtained 1 hour before neurally adjusted ventilatory assist and 1, 4, 12, and 24 hours after conversion to neurally adjusted ventilatory assist. During neurally adjusted ventilatory assist, the peak inspiratory pressure (20.12 ± 2.93 vs 14.15 ± 3.55 cm H2O; p < 0.05), mean airway pressure (11.15 ± 1.29 vs 9.57 ± 1.27 cm H2O; p < 0.05), and work of breathing (0.86 ± 0.22 vs 0.46 ± 0.12 J/L; p < 0.05) were significantly decreased, and the blood gas values were significantly improved. Significantly lower FIO2 and improved oxygen saturation were observed during neurally adjusted ventilatory assist compared with conventional ventilation support. The RSS values decreased and sustained during neurally adjusted ventilatory assist (4.85 ± 1.63 vs 3.21 ± 1.01; p < 0.001).

CONCLUSIONS

The transition from synchronized intermittent mandatory ventilation to neurally adjusted ventilatory assist ventilation was associated with improvements in ventilator variables, oxygen saturation, and blood gas values in infants with bronchopulmonary dysplasia in a single center. This study suggests the possible clinical utility of neurally adjusted ventilatory assist as a weaning modality for bronchopulmonary dysplasia patients in the neonatal ICU.

Glucocorticoid Effects on Cerebellar Development in a Chicken Embryo Model: Exploring Changes in PAX6 and Metalloproteinase-9 After Exposure to Dexamethasone

The developing cerebellum is vulnerable to effects of glucocorticoids and cerebellar dysfunction is associated with neurodevelopmental disorders (e.g. autism). Transcription factor PAX6 and matrix metalloproteinase-9 (MMP-9) are critical for normal cerebellar development and are highly expressed in migrating neurones. Alterations in MMP-9 and PAX6 are associated with altered cerebellar development. In the present study, we characterised the growth rate and development of the cortical layers, and further investigated how the levels of PAX6 and MMP-9, as well as glucocorticoid receptor (GR) and proliferating cell nuclear antigen (PCNA), change in the cerebellum during the foetal period [embryonic day (E)12-21] in chicken, which corresponds to the human perinatal period. Dexamethasone (DEX) was administered in ovo at E13 and E16, aiming to investigate how prenatal exposure to glucocorticoids interferes with normal development. DEX reduced foetal and cerebellar weight at E17 in a dose-dependent manner linked to a reduced level of PCNA and, over time, down-regulation of GR. We report that promoter activity of PAX6 and MMP-9 increased as a result of GR-stimulation in vitro. Prenatal DEX increased the protein level of PAX6 in a transient manner. PAX6 is reduced in mature granule neurones, and this occurred earlier in embryos exposed to DEX than in non-exposed controls. DEX exposure also led to a slow-onset down-regulation of MMP-9. Taken together, these findings indicate that excess prenatal glucocorticoid stimulation disturbs normal development of the cerebellum through mechanisms associated with reduced proliferation and accelerated maturation where PAX6 and MMP-9 play important roles.

Civil capacity in transition-age youth with history of central nervous system compromise: a review

OBJECTIVE

The purpose of this paper is to review various aspects of decision-making capacities in children and adolescents with a history of central nervous system compromise over the course of development and into transition to adulthood.

METHOD

The literature on consent capacity in various domains is reviewed, with reference to state-specific legal definitions and requirements, and illustrated with a case example.

CONCLUSIONS

Neuropsychologists who use an evidence-based assessment approach, and who can clearly communicate their findings in reference to specific probate court standards, can make a unique contribution to the legal system while serving their clients who are transitioning from adolescence into adulthood.

Loss of PINK1 inhibits apoptosis by upregulating α-synuclein in inflammation-sensitized hypoxic-ischemic injury in the immature brains

The incidence of preterm birth is rising worldwide. Among preterm infants, many face a lifetime of neurologic impairments. Recent studies have revealed that systemic inflammation can sensitize the immature brain to hypoxic-ischemic (HI) injury. Therefore, it is important to identify the mechanisms involved in inflammation-sensitized HI injury in immature brains. PTEN-induced putative kinase 1 (PINK1) is a regulatory protein that is highly expressed in the brain. We have previously found that PINK1 gene knockout can protect matured brains from HI injury in postnatal day 10 mice. However, the mechanisms are unknown. In this study, we employed an inflammation-sensitized HI injury model using postnatal day 3 mice to study the roles and mechanisms that PINK1 plays in the immature brains. Lipopolysaccharide (LPS) was injected intraperitoneally into the mice before HI treatment to set up the model. We found that PINK1-knockout mice had fewer brain infarcts and less cell apoptosis than did the wild-type mice. Furthermore, we found that α-synuclein was markedly higher in the PINK1-knockout mice than in the wild-type mice, and inhibition of α-synuclein through small interfering RNA (siRNA) reversed the protective effect in the PINK1-knockout mice. Collectively, these findings indicate that loss of PINK1 plays a novel role in the protection of inflammation-sensitized HI brain damage.

Overall Profile of a Pediatric Multidisciplinary Feeding Clinic

Objective

To evaluate the overall profile of children with feeding disorders and their relationships to medical conditions in an outpatient feeding clinic of a tertiary hospital.

Methods

The medical records of 143 children who had visited the feeding clinic between January 2010 and June 2014 were reviewed retrospectively. The presence of a feeding disorder (feeding behavior disorder, dysphagia, and/or failure to thrive [FTT]) and the children's medical conditions were examined by a physiatrist.

Results

Half of the patients (n=74, 51.7%) were under 15 months of age, and 68 (47.6%) were born preterm. Ninety-three patients (65.0%) met the criteria for any combination of feeding behavior disorder, dysphagia, or FTT. Cardiorespiratory disease was the most common medical condition; children with this condition were more likely to show sensory food aversion and FTT. Feeding behavior disorders were significantly associated with gastrointestinal problems, and dysphagia was significantly related to almost all medical conditions.

Conclusion

A multidisciplinary approach to children with feeding difficulties is proposed for comprehensive evaluation and treatment because combinations of feeding problems are very common among children. This overall profile could provide clinicians with a clear understanding of the complexity of feeding disorders and their relationships with various medical conditions in children.

National Perspective of Health Outcomes of 8- to 11-Year-Old Children Born Prematurely and Their Full-Term Peers

The specific aim of this study was to evaluate the health sequelae of preterm birth on children 8 to 11years of age as compared to same age children born at term; selected variables include special health care needs, chronic conditions, and caregiver perception of health.

DESIGN/METHODS

A secondary data analysis was conducted to evaluate the health outcomes of children 8 to 11years of age who were born prematurely compared to a sample of children born at term. The 2011/2012 National Survey of Children's Health (NSCH) is a nationally representative telephone interview survey of parents/caregivers of children 0 to 17years of age. Preterm birth was determined by parent report of birth more than 3weeks early.

RESULTS

Utilizing the Children with Special Health Care Needs (CSHCN) Screener, 35% of children born prematurely, compared to 24% of children born at term were identified as having a special health care need. The 5 most prevalent conditions were the same in both groups of 8 to 11year old children and in the larger total sample of children 2 to 17years of age. However 82% of children born prematurely were described by parents as having excellent or very good health.

CONCLUSIONS

Premature birth places children at increased risk for conditions that impede the crucial activities of childhood (education, psychosocial development and play). These conditions may require both medications and increased health care services.

IMPLICATIONS FOR PRACTICE

Understanding the relationship between preterm birth and ongoing health risks has the potential to inform the health care providers' ability to provide care that maximizes the potential of children born prematurely. Health care providers need to be cognizant of this risk, utilizing early screening and encouraging intervention and family supports.

Survival Among Infants Born at 22 or 23 Weeks' Gestation Following Active Prenatal and Postnatal Care

IMPORTANCE

Rates of survival for infants born at the border of viability are still low and vary considerably among neonatal intensive care units.

OBJECTIVE

To determine whether higher survival rates and better short-term outcomes for infants born at 22 or 23 weeks' gestation may be achieved by active prenatal and postnatal care.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective study of 106 infants born at 22 or 23 weeks of gestation at a level III neonatal intensive care unit at the University of Cologne Medical Centre in Cologne, Germany, between January 1, 2010, and December 31, 2014. Data analysis was performed in June 2015.

EXPOSURES

Active prenatal and postnatal care.

MAIN OUTCOMES AND MEASURES

Survival until hospital discharge and survival without neonatal or short-term severe complications (defined as high-grade intraventricular hemorrhage, surgery for abdominal complications, bronchopulmonary dysplasia, or retinopathy of prematurity).

RESULTS

Of 106 liveborn infants (45 born at 22 weeks and 61 born at 23 weeks and 6 days), 20 (19%) received palliative care (17 born at 22 weeks and 3 born at 23 weeks), and 86 (81%) received active care (28 born at 22 weeks and 58 born at 23 weeks). Of the 86 infants who received active care (mean [SD] maternal age, 32 [6] years), 58 (67%) survived until hospital discharge (17 born at 22 weeks and 41 born at 23 weeks). Eighty-five infants survived without severe complications, with 1 infant born at 22 weeks excluded because of missing data (6 of 27 [22%] born at 22 weeks, and 16 of 58 [28%] born at 23 weeks). Survival was predicted by the Apgar score after 5 minutes (odds ratio, 0.62 [95% CI, 0.46-0.84]) and birth weight (odds ratio, 0.001 [95% CI, 0.00-0.40]).

CONCLUSIONS AND RELEVANCE

One in 4 infants born at the border of viability and offered active care survived without severe complications. This finding should be considered for individualized parental approaches and decision making. Active follow-up information is required to determine childhood outcomes.

Relationship between Proton Magnetic Resonance Spectroscopy of Frontoinsular Gray Matter and Neurodevelopmental Outcomes in Very Low Birth Weight Children at the Age of 4

Very low birth weight is associated with long term neurodevelopmental complications. Macroscopic brain abnormalities in prematurity survivors have been investigated in several studies. However, there is limited data regarding local cerebral metabolic status and neurodevelopmental outcomes. The purpose of this study was to characterize the relationship between proton magnetic resonance spectra in basal ganglia, frontal white matter and frontoinsular gray matter, neurodevelopmental outcomes assessed with the Leiter scale and the Developmental Test of Visual Perception and selected socioeconomic variables in a cohort of very low birth weight children at the age of four. Children were divided in three groups based on the severity of neurodevelopmental impairment. There were no differences in spectroscopy in basal ganglia and frontal white matter between the groups. Lower concentrations of N-acetylaspartate (NAA), choline (Cho) and myoinositol (mI) were observed in the frontoinsular cortex of the left hemisphere in children with neurodevelopmental impairment compared to children with normal neurodevelopmental outcomes. Higher parental education, daycare attendance and breastfeeding after birth were associated with more favorable neurodevelopmental prognosis, whereas rural residence was more prevalent in children with moderate and severe impairment. Our study demonstrates the role of long term neurometabolic disruption in the left frontoinsular cortex and selected socioeconomic variables in determination of neurodevelopmental prognosis in prematurity survivors.

Neurofunctional assessment at term equivalent age can predict 3-year neurodevelopmental outcomes in very low birth weight infants

AIM

Preterm infants are at high risk of developing motor delay, learning difficulties and behavioural problems and the availability of valid neurodevelopmental assessments is a major clinical issue. This study evaluated the relationship between preterm infants' neurofunctional assessment at term equivalent age and neurodevelopment outcome at three years of chronological age.

METHODS

Neurofunctional assessment was performed in 70 very low birth weight infants at term equivalent age and neurodevelopmental outcome was assessed at three years of chronological age with the Griffiths Mental Development Scale - Extended Revised.

RESULTS

At term equivalent age, 81% of the children had normal neurofunctional scores and 82.5% of those showed normal neurodevelopmental outcome at three years. Of the 19% who had impaired development at term equivalent age, 38.5% had neurodevelopmental delay at three years. Impaired neurofunctional status was associated with an increased risk of developmental delay in the global quotient (odds ratio 12.1) and locomotor sub-quotient (odds ratio 18.35) compared with normal neurofunctional status. Infants with sepsis or necrotising enterocolitis also faced a higher risk of neurodevelopmental delay.

CONCLUSION

Neurofunctional assessment performed at term equivalent age appeared to provide early identification of preterm infants at risk of neurodevelopmental delay at three years of chronological age.

Using cluster analysis to provide new insights into development of very low birthweight (VLBW) premature infants

BACKGROUND

Very low birthweight (VLBW) premature infant follow-up studies report on single developmental outcome variables but do not assess profiles of development.

AIMS

To identify developmental profiles of VLBW premature infants based on cognitive and language development and their association with demographic, perinatal, and behavior variables.

STUDY DESIGN

Retrospective chart review.

SUBJECTS

117 children<1250 g BW seen at 18 months post-term on the Bayley Scales-III and Child Behavior Checklist 1 ½-5 (CBCL 1 ½-5), a behavior problem questionnaire. Demographic and perinatal variables were obtained from medical records.

OUTCOME MEASURES

Bayley Cognitive, Expressive Language, and Receptive Language scores were used to cluster the subjects into developmental profiles. Demographic, perinatal, and CBCL variables were analyzed as they related to clusters.

RESULTS

Children were clustered into 4 groups based on their Bayley Cognitive, Expressive Language, and Receptive Language scores: Consistently High, Consistently Average, Average with Delayed Expressive Language, and Consistently Low. Socioeconomic status, bronchopulmonary dysplasia, Grades III-IV intraventricular hemorrhage, and summary Behavior Problems and Attention Deficit/Hyperactivity (ADHD) Problems scores were significantly related to clusters.

CONCLUSION

Cluster analysis defined distinct outcome groups in VLBW premature children and provides an informative means of identifying factors related to developmental outcome. This approach may be useful in predicting later outcome and determining which groups of children will require early intervention.

White Matter Injury in Premature Newborns

Preterm newborns are highly susceptible to brain injury. White matter injury is among the dominant patterns of brain injury in preterm newborns. the purpose of this review is to discuss the pathogenesis, diagnosis, management, and prevention of white matter injury in premature newborns. the long-term outcome of white matter injury in children born prematurely is also addressed.

Increased risk of psychosis in patients with hearing impairment: Review and meta-analyses

Several studies suggest hearing impairment as a risk factor for psychosis. Hearing impairment is highly prevalent and potentially reversible, as it can be easily diagnosed and sometimes improved. Insight in the association between hearing impairment and psychosis can therefore contribute to prevention of psychosis. This paper provides meta-analyses of all epidemiologic evidence on the association between hearing impairment and psychosis and summarizes mechanisms that potentially underlie this relationship. Meta-analyses showed an increased risk of hearing impairment on all psychosis outcomes, such as hallucinations (OR 1.40(95%CI 1.18-1.65; n=227,005)), delusions (OR 1.55(95%CI 1.36-1.78; n=250,470)), psychotic symptoms (OR 2.23(95%CI 1.83-2.72; n=229,647) and delirium (OR 2.67(95%CI 2.05-3.48; n=12,432). Early exposure to hearing impairment elevated the risk of later development of schizophrenia (OR 3.15(95%CI 1.25-7.95; n=50,490)). Potential mechanisms underlying this association include loneliness, diminished theory of mind, disturbances of source monitoring and top-down processing and deafferentiation. Early assessment and treatment of hearing impairment in patients with (high risk of) psychosis may be essential in psychosis treatment and prevention.

Brain structural and microstructural alterations associated with cerebral palsy and motor impairments in adolescents born extremely preterm and/or extremely low birthweight

AIM

To elucidate neurobiological changes underlying motor impairments in adolescents born extremely preterm (gestation <28wks) and/or with extremely low birthweight (ELBW, <1000g), our aims were the following: (1) to compare corticospinal tract (CST) microstructure and primary motor cortex (M1) volume, area, and thickness between extremely preterm/ELBW adolescents and a comparison group with normal birthweight (>2499g); (2) to compare CST microstructure and M1 volume, area, and thickness between extremely preterm/ELBW adolescents with cerebral palsy (CP), motor impairment without CP, and no motor impairment; and (3) to investigate associations between CST microstructure and M1 measures.

METHOD

This study used diffusion and structural magnetic resonance imaging to examine the CST and M1 in a geographical cohort of 191 extremely preterm/ELBW adolescents (mean age 18y 2.4mo [SD 9.6mo]; 87 males, 104 females) and 141 adolescents in the comparison group (mean age 18y 1.2mo [SD 9.6mo]; 59 males, 82 females).

RESULTS

Extremely preterm/ELBW adolescents had higher CST axial, radial, and mean diffusivities and lower M1 thickness than the comparison group. Extremely preterm/ELBW adolescents with CP had higher CST diffusivities than non-motor-impaired extremely preterm/ELBW adolescents. CST diffusivities correlated with M1 volume and area.

INTERPRETATION

Extremely preterm/ELBW adolescents have altered CST microstructure, which is associated with CP. Furthermore, the results elucidate how CST and M1 alterations interrelate to potentially influence motor function in extremely preterm/ELBW adolescents.

Magnesium sulfate has sex-specific, dose-dependent vasodilator effects on preterm placental vessels

Background

Women at risk of preterm delivery receive magnesium sulfate (MgSO₄) in the pre-delivery phase to reduce their child’s risk of neurodevelopmental complications associated with preterm birth. However, the mechanisms underpinning its placental vascular role remain uncertain.

Methods

The aim of this study was to examine MgSO₄ action on vascular tone in male and female human placental vessels from term and preterm deliveries. Vessels were obtained from placental biopsy following birth at term (37–41 weeks) or preterm gestation (<36 weeks of gestation). The vessels were mounted on a pressure myograph, pre-constricted with synthetic endoperoxide prostaglandin PGH₂ (U46619) (0.1–100 μmol/l), and percentage of relaxation was calculated following incubation with bradykinin. Experiments were carried out in the presence of MgSO₄ (0.2 mmol/l), N_Ψ-nitro-L-arginine methyl ester (L-NAME) (0.1 mmol/l), indomethacin (10 μmol/l), Ca²⁺-activated K⁺ channel blocker TRAM-34 (1 μM) and apamin (3 μM) to assess mechanisms of vascular function. Vascular [calcium ions (Ca²⁺)] was analysed using a colorimetric calcium assay.

Results

Vasodilation in vessels from preterm males was significantly blunted in the presence of MgSO₄ when compared to preterm female and term male and female vessels. Overall, MgSO₄ was observed to differentially modulate placental vascular tone and vascular calcium concentrations in a sex-specific manner.

Conclusions

As MgSO₄ regulates human placental blood flow via specific pathways, foetal sex-specific MgSO₄ treatment regimes may be necessary. In an era of increasing awareness of individualised medicine, sex-specific effects may be of importance when developing strategies to optimise care in high-risk patients.

Is the ferret a suitable species for studying perinatal brain injury?

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Ferret brain architecture, composition, and development are similar to humans.

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Postnatal ferret brain development is comparable to that of premature infants.

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Ferrets have potential to model preterm and term neonatal brain injury.

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Ferrets may fulfill the need for an intermediate model species of neurodevelopment.

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Many opportunities exist to expand the use of ferrets as research subjects.

Complications of prematurity often disrupt normal brain development and/or cause direct damage to the developing brain, resulting in poor neurodevelopmental outcomes. Physiologically relevant animal models of perinatal brain injury can advance our understanding of these influences and thereby provide opportunities to develop therapies and improve long-term outcomes. While there are advantages to currently available small animal models, there are also significant drawbacks that have limited translation of research findings to humans. Large animal models such as newborn pig, sheep and nonhuman primates have complex brain development more similar to humans, but these animals are expensive, and developmental testing of sheep and piglets is limited. Ferrets (Mustela putorius furo) are born lissencephalic and undergo postnatal cortical folding to form complex gyrencephalic brains. This review examines whether ferrets might provide a novel intermediate animal model of neonatal brain disease that has the benefit of a gyrified, altricial brain in a small animal. It summarizes attributes of ferret brain growth and development that make it an appealing animal in which to model perinatal brain injury. We postulate that because of their innate characteristics, ferrets have great potential in neonatal neurodevelopmental studies.