Fetal intrauterine growth restriction (IUGR) is a serious pregnancy complication associated with increased rates of perinatal morbidity and mortality, and ultimately with long-term neurodevelopmental impairments. No intervention currently exists that can improve the structure and function of the IUGR brain before birth. Here, we investigated whether maternal antenatal melatonin administration reduced brain injury in ovine IUGR. IUGR was induced in pregnant sheep at 0.7 gestation and a subset of ewes received melatonin via intravenous infusion until term. IUGR, IUGR + melatonin (IUGR + MLT) and control lambs were born naturally, neonatal behavioral assessment was used to examine neurological function and at 24 hr after birth the brain was collected for the examination of neuropathology. Compared to control lambs, IUGR lambs took significantly longer to achieve normal neonatal lamb behaviors, such as standing and suckling. IUGR brains showed widespread cellular and axonal lipid peroxidation, and white matter hypomyelination and axonal damage. Maternal melatonin administration ameliorated oxidative stress, normalized myelination and rescued axonopathy within IUGR lamb brains, and IUGR + MLT lambs demonstrated significant functional improvements including a reduced time taken to attach to and suckle at the udder after birth. Based on these observations, we began a pilot clinical trial of oral melatonin administration to women with an IUGR fetus. Maternal melatonin was not associated with adverse maternal or fetal effects and it significantly reduced oxidative stress, as evidenced by reduced malondialdehyde levels, in the IUGR + MLT placenta compared to IUGR alone. Melatonin should be considered for antenatal neuroprotective therapy in human IUGR.

A compromised intrauterine environment that delivers low levels of oxygen and/or nutrients, or is infected or inflammatory, can result in fetal brain injury, abnormal brain development and in cases of chronic compromise, intrauterine growth restriction. Preterm birth can also be associated with injury to the developing brain and affect the normal trajectory of brain growth. This review will focus on the effects that episodes of perinatal hypoxia (acute, chronic, associated with inflammation or as an antecedent of preterm birth) can have on the developing brain. In animal models of these conditions we have found that relatively brief (acute) periods of fetal hypoxemia can have significant effects on the fetal brain, for example death of susceptible neuronal populations (cerebellum, hippocampus, cortex) and cerebral white matter damage. Chronic placental insufficiency which includes fetal hypoxemia, nutrient restriction and altered endocrine status can result in fetal growth restriction and long-term deficits in neural connectivity in addition to altered postnatal function, for example in the auditory and visual systems. Maternal/fetal inflammation can result in fetal brain damage, particularly but not exclusively in the white matter; injury is more pronounced when associated with fetal hypoxemia. In the baboon, in which the normal trajectory of growth is affected by preterm birth, there is a direct correlation between a higher flux in oxygen saturation and a greater extent of neuropathological damage. Currently, the only established therapy for neonatal encephalopathy in full term neonates is moderate hypothermia although this only offers some protection to moderately but not severely affected brains. There is no accepted therapy for injured preterm brains. Consequently the search for more efficacious treatments continues; we discuss neuroprotective agents (erythropoietin, N-acetyl cysteine, melatonin, creatine, neurosteroids) which we have trialed in appropriate animal models. The possibility of combining hypothermia with such agents or growth factors is now being considered. A deeper understanding of causal pathways in brain injury is essential for the development of efficacious strategies for neuroprotection.

The kynurenine pathway (KP) of tryptophan metabolism is linked to antimicrobial activity and modulation of immune responses but its role in stem cell biology is unknown. We show that human and mouse mesenchymal and neural stem cells (MSCs and NSCs) express the complete KP, including indoleamine 2,3 dioxygenase 1 (IDO) and IDO2, that it is highly regulated by type I (IFN-β) and II interferons (IFN-γ), and that its transcriptional modulation depends on the type of interferon, cell type and species. IFN-γ inhibited proliferation and altered human and mouse MSC neural, adipocytic and osteocytic differentiation via the activation of IDO. A functional KP present in MSCs, NSCs and perhaps other stem cell types offers novel therapeutic opportunities for optimisation of stem cell proliferation and differentiation.

Oxygen free radicals, including the highly toxic hydroxyl radical (^·OH), initiate lipid peroxidation and DNA/RNA fragmentation and damage cells. The pineal hormone melatonin is an antioxidant and powerful scavenger of ^·OH. We hypothesized that maternally administered melatonin could reduce ^·OH formation, lipid peroxidation, and DNA/RNA damage in the fetal brain in response to asphyxia. In 15 fetal sheep, extracellular ^·OH was measured by microdialysis in white and gray matter of the parasagittal cortex. In 10 fetuses, asphyxia was induced by umbilical cord occlusion for 10 min using an inflatable cuff – the ewes of these fetuses received either intravenous melatonin (1 mg bolus, then 1 mg/h for 2 h; n = 5) or vehicle (1% ethanol in saline; n = 5), and results were compared to fetuses with sham cord occlusion and vehicle-infused ewes (n = 5). Hypoxemia, acidemia, hypertension and bradycardia produced by cord occlusion was similar in the melatonin- and vehicle-treated groups. In the vehicle-treated group, cord occlusion resulted in a significant increase in ^·OH in gray matter at 8–9.5 h after occlusion (p < 0.05); in contrast, there was no ^·OH change in the melatonin-treated group. After cord occlusion, lipid peroxidation (4-hydroxynonenal immunoreactivity) found throughout the brain of vehicle-infused ewes was significantly less in the melatonin-infused group. Melatonin had no significant effect on the distribution of DNA/RNA fragmentation, as shown by 8-hydroxydeoxyguanosine immunoreactivity. Thus, brief asphyxia results in significant and delayed entry of ^·OH into the extracellular space of cortical gray matter in the fetal sheep brain, and melatonin given to the mother at the time of the insult abrogates this increase. Melatonin, in reducing O₂ free radical production, may be an effective neuroprotective treatment for the fetus.

As clinicians attempt to understand the underlying reasons for the vulnerability of different regions of the developing brain to injury, it is apparent that little is known as to how hypoxia-ischemia may affect the cerebrovasculature in the developing infant. Most of the research investigating the pathogenesis of perinatal brain injury following hypoxia-ischemia has focused on excitotoxicity, oxidative stress and an inflammatory response, with the response of the developing cerebrovasculature receiving less attention. This is surprising as the presentation of devastating and permanent injury such as germinal matrix-intraventricular haemorrhage (GM-IVH) and perinatal stroke are of vascular origin, and the origin of periventricular leukomalacia (PVL) may also arise from poor perfusion of the white matter. This highlights that cerebrovasculature injury following hypoxia could primarily be responsible for the injury seen in the brain of many infants diagnosed with hypoxic-ischemic encephalopathy (HIE). Interestingly the highly dynamic nature of the cerebral blood vessels in the fetus, and the fluctuations of cerebral blood flow and metabolic demand that occur following hypoxia suggest that the response of blood vessels could explain both regional protection and vulnerability in the developing brain. However, research into how blood vessels respond following hypoxia-ischemia have mostly been conducted in adult models of ischemia or stroke, further highlighting the need to investigate how the developing cerebrovasculature responds and the possible contribution to perinatal brain injury following hypoxia. This review discusses the current concepts on the pathogenesis of perinatal brain injury, the development of the fetal cerebrovasculature and the blood brain barrier (BBB), and key mediators involved with the response of cerebral blood vessels to hypoxia.

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Intrauterine growth restriction (IUGR) is associated with altered fetal cardiovascular function to ensure adequate perfusion of essential organs. IUGR fetuses are at risk of preterm delivery and so are likely to receive antenatal glucocorticoids to promote lung maturation. Because glucocorticoids alter vascular tone, we questioned whether such treatment may induce fetal cardiovascular alterations. Using pregnant sheep carrying twins, we induced IUGR at approximately 0.7 gestation by single umbilical artery ligation in one twin, using the other twin as a control. In each fetus, we monitored carotid blood flow and arterial blood gases. We administered 11.4 mg betamethasone (n = 5) or vehicle (n = 4) to the ewe on d 5 (BM1) and 6 (BM2) postsurgery. On d 7, fetal brains were collected for immunohistochemistry. In control fetuses, carotid blood flow decreased 3.5 h post-BM1 by 24% (P < 0.001), returning to baseline at 5.5 h. In IUGR fetuses, carotid flow decreased 2.5 h post-BM1 by 27% and then increased by 25% over baseline, peaking at 11 h (P < 0.001). Compared to control + saline, we observed a significant increase in oxidative damage (4-hydroxynonenal-positive cells) in the fetal hippocampus and subcallosal area of all treatment groups (IUGR + BM > IUGR + saline = control + BM). There was a significant correlation between carotid blood flow reperfusion after betamethasone and the number of 4-hydroxynonenal-positive cells in the cortex and hippocampus. These data suggest that antenatal betamethasone may induce brain injury in the IUGR fetus but not in the normally grown fetus.

Objective: The aim of the study was to determine whether perforated appendicitis rates in children were influenced by the Coronavirus disease 2019 (COVID-19) surge. Background: Disruption of care pathways during a public health crisis may prevent children from obtaining prompt assessment for surgical conditions. Progression of appendicitis to perforation is influenced by timeliness of presentation. In the context of state-mandated controls and public wariness of hospitals, we investigated the impact of the COVID-19 outbreak on perforated appendicitis in children. Study Design: We conducted an analysis of all children presenting to 3 hospital sites with acute appendicitis between March 1 and May 7, 2020, corresponding with the peak COVID-19 outbreak in the New York City region. Control variables were collected from the same institutions for the preceding 5 years. The primary outcome measure was appendiceal perforation. Results: Fifty-five children presented with acute appendicitis over 10 weeks. Compared to a 5-year control cohort of 1291 patients, we observed a higher perforation rate (45% vs 27%, odds ratio 2.23, 95% confidence interval 1.29–3.85, P = 0.005) and longer mean duration of symptoms in children with perforations (71 ± 39 vs 47 ± 27 h, P = 0.001) during the COVID-19 period. There were no differences in perforation rates (55% vs 59%, P = 0.99) or median length of stay (1.0 vs 3.0 days, P = 0.58) among children screening positive or negative for SARS-CoV-2. Conclusions: Children in the epicenter of the COVID-19 outbreak demonstrated higher rates of perforated appendicitis compared to historical controls. Preoperative detection of SARS-CoV-2 was not associated with inferior outcomes. Although children likely avoid much of the morbidity directly linked to COVID-19, disruption to local healthcare delivery systems may negatively impact other aspects of pediatric surgical disease.