Post-insult minocycline treatment attenuates hypoxia-ischemia-induced neuroinflammation and white matter injury in the neonatal rat: a comparison of two different dose regimens

An increase in the number of activated microglia in the brain is a key feature of neuroinflammation after a hypoxic-ischemic insult to the preterm neonate and can contribute to white matter injury in the brain. Minocycline is a potent inhibitor of microglia and may have a role as a neuroprotective agent that ameliorates brain injury after hypoxia-ischemia in neonatal animal models. However to date large doses, pre-insult administration and short periods of treatment after hypoxia-ischemia have mostly been investigated in animal models making it difficult to translate minocycline's potential applicability to protect the human preterm neonatal brain exposed to hypoxia-ischemia. We investigated whether repeated doses of minocycline can minimize white matter injury and neuroinflammation one week after hypoxia-ischemia (right carotid artery ligation and 30 min 6% O(2)) in the post-natal day 3 rat pup. Two dosage regimens of minocycline were administered for one week; a high dose of 45 mg/kg 2h after hypoxia-ischemia then 22.5 mg/kg daily or a low dose 22.5 mg/kg 2h after hypoxia-ischemia then 10 mg/kg. Post-natal day 3 hypoxia-ischemia significantly reduced myelin content, numbers of O1- and O4-positive oligodendrocyte progenitor cells and increased activated microglia one week later on post-natal day 10. The low dose minocycline regimen was as effective as the high dose in ameliorating neuroinflammation after post-natal day 3 hypoxia-ischemia. However only the high dose regimen significantly attenuated reductions in O1- and O4-positive oligodendrocyte progenitor cells and myelin content. The low dose only significantly attenuated the reduction in O1-positive oligodendrocyte cell counts. Repeated, daily, post-insult treatment with minocycline abolished neuroinflammation and may provide neuroprotection to white matter for up to one week after hypoxia-ischemia in a rodent preterm model. The present findings suggest the potential clinical relevance of a repeated, daily minocycline treatment strategy, administered after a hypoxia-ischemia insult, as a therapeutic intervention for hypoxia-ischemia-affected preterm neonates.

Review: Neuroinflammation in intrauterine growth restriction

Disruption to the maternal environment during pregnancy from events such as hypoxia, stress, toxins, inflammation, and reduced placental blood flow can affect fetal development. Intrauterine growth restriction (IUGR) is commonly caused by chronic placental insufficiency, interrupting supply of oxygen and nutrients to the fetus resulting in abnormal fetal growth. IUGR is a major cause of perinatal morbidity and mortality, occurring in approximately 5-10% of pregnancies. The fetal brain is particularly vulnerable in IUGR and there is an increased risk of long-term neurological disorders including cerebral palsy, epilepsy, learning difficulties, behavioural difficulties and psychiatric diagnoses. Few studies have focused on how growth restriction interferes with normal brain development in the IUGR neonate but recent studies in growth restricted animal models demonstrate increased neuroinflammation. This review describes the role of neuroinflammation in the progression of brain injury in growth restricted neonates. Identifying the mediators responsible for alterations in brain development in the IUGR infant is key to prevention and treatment of brain injury in these infants.

Minocycline: a neuroprotective agent for hypoxic-ischemic brain injury in the neonate?

Minocycline is a second-generation tetracycline and a potential neuroprotective intervention following brain injury. However, despite the recognized beneficial effects of minocycline in a multitude of adult disease states, the clinical application of minocycline in neonates is contentious. Tetracyclines, as a class, are not usually administered to neonates, but there is compelling evidence that minocycline reduces brain injury after neonatal hypoxic-ischemic brain injury. This Review focuses on the evidence for minocycline use in neonates by considering aspects of pharmacology, drug regimens, functional outcomes, and mechanisms of action.

Increased expression of neuronal glucose transporter 3 but not glial glucose transporter 1 following severe diffuse traumatic brain injury in rats

Traumatic brain injury results in an increased brain energy demand that is associated with profound changes in brain glycolysis and energy metabolism. Increased glycolysis must be met by increasing glucose supply that, in brain, is primarily mediated by two members of the facilitative glucose transporter family, Glut1 and Glut3. Glut1 is expressed in endothelial cells of the blood-brain barrier (BBB) and also in glia, while Glut3 is the primary glucose transporter expressed in neurons. However, few studies have investigated the changes in glucose transporter expression following traumatic brain injury, and in particular, the neuronal and glial glucose transporter responses to injury. This study has therefore focussed on investigating the expression of the glial specific 45-kDa isoform of Glut1 and neuronal specific Glut3 following severe diffuse traumatic brain injury in rats. Following impact-acceleration injury, Glut3 expression was found to increase by at least 300% as early as 4 h after induction of injury and remained elevated for at least 48 h postinjury. The increase in Glut3 expression was clearly evident in both the cerebral cortex and cerebellum. In contrast, expression of the glial specific 45-kDa isoform of Glut1 did not significantly change in either the cerebral cortex or cerebellum following traumatic injury. We conclude that increased glucose uptake after traumatic brain injury is primarily accounted for by increased neuronal Glut 3 glucose transporter expression and that this increased expression after trauma is part of a neuronal stress response that may be involved in increasing neuronal glycolysis and associated energy metabolism to fuel repair processes.

Expression of MBP, PLP, MAG, CNP, and GFAP in the Human Alcoholic Brain

BACKGROUND

Chronic and excessive alcohol misuse results in neuropathological damage in the cerebral cortex. The damage includes white matter loss, brain atrophy, and selective loss of neurons in the superior frontal gyrus. Chronic alcohol misuse also results in alterations in the expression of a number of genes, including a selective reprogramming of myelin gene expression in the frontal cortex.

METHODS

The expression of cyclic nucleotide phosphodiesterase, glial fibrillary acidic protein, myelin-associated glycoprotein, myelin basic protein, and myelin proteolipid protein were assessed in the superior frontal gyrus and the primary motor cortex of control, uncomplicated alcoholic, and cirrhotic alcoholic cases.

RESULTS

Overall, the expression of cyclic nucleotide phosphodiesterase, glial fibrillary acidic protein, myelin-associated glycoprotein, and myelin basic protein were significantly lower in the cirrhotic alcoholic cases compared with controls, with a similar tendency for myelin proteolipid protein. There was a strong correlation between the expression of the proteins studied and the brain weight of the individual case, but this interaction did not confound the overall analysis. There was no significant difference between controls and uncomplicated alcoholics.

CONCLUSIONS

The loss of myelin proteins occurred without gross changes in brain pathology or brain weight and was not restricted to pathologically susceptible brain regions. It is not possible to determine whether the loss of myelin proteins in cirrhotic alcoholics is the result of cirrhosis per se or the combination of alcohol misuse and liver cirrhosis. Future studies comparing cases with alcoholic and nonalcoholic cirrhosis of the liver disease are required to elucidate this further.

Contribution of germline mutations in BRCA2, P16(INK4A), P14(ARF) and P15 to uveal melanoma

PURPOSE

Reports suggest that a subset of uveal melanoma is familial. The association of uveal melanoma with breast and ovarian cancer and the increased risk in BRCA2-linked families implicates germline BRCA2 mutations as the cause of a subset of uveal melanomas. Similarly, the association between cutaneous and uveal melanomas in some families, coupled with the high frequency of somatic deletions of the INK4A-ARF locus in uveal melanomas, strongly suggests that mutations in P16(INK4A) and P15 account for a proportion of uveal melanomas.

METHODS

To examine this proposition, a systematically ascertained series of 385 patients with uveal melanoma were screened for germline mutations in BRCA2, P16(INK4A), P14(ARF), and P15.

RESULTS

One patient was found to harbor a Gly35Ala substitution in exon 1alpha of P16(INK4A), which has previously been reported to be pathogenic. No mutations were detected in P14(ARF) or P15. None of the patients harbored germline nucleotide changes that lead to truncation or that create or disrupt consensus splice sites of BRCA2 or missense variants with clear pathogenic potential.

CONCLUSIONS

These findings suggest that less than 2% of cases of uveal melanoma can be ascribed to germline mutations in BRCA2, P16(INK4A), P14(ARF), or P15. It is likely that mutations in other genes contribute to an inherited predisposition to uveal melanoma.

Neuropathology in intrauterine growth restricted newborn piglets is associated with glial activation and proinflammatory status in the brain

BACKGROUND

The fetal brain is particularly vulnerable to intrauterine growth restriction (IUGR) conditions evidenced by neuronal and white matter abnormalities and altered neurodevelopment in the IUGR infant. To further our understanding of neurodevelopment in the newborn IUGR brain, clinically relevant models of IUGR are required. This information is critical for the design and implementation of successful therapeutic interventions to reduce aberrant brain development in the IUGR newborn. We utilise the piglet as a model of IUGR as growth restriction occurs spontaneously in the pig as a result of placental insufficiency, making it a highly relevant model of human IUGR. The purpose of this study was to characterise neuropathology and neuroinflammation in the neonatal IUGR piglet brain.

METHODS

Newborn IUGR (< 5th centile) and normally grown (NG) piglets were euthanased on postnatal day 1 (P1; < 18 h) or P4. Immunohistochemistry was utilised to examine neuronal, white matter and inflammatory responses, and PCR for cytokine analysis in parietal cortex of IUGR and NG piglets.

RESULTS

The IUGR piglet brain displayed less NeuN-positive cells and reduced myelination at both P1 and P4 in the parietal cortex, indicating neuronal and white matter disruption. A concurrent decrease in Ki67-positive proliferative cells and increase in cell death (caspase-3) in the IUGR piglet brain was also apparent on P4. We observed significant increases in the number of both Iba-1-positive microglia and GFAP-positive astrocytes in the white matter in IUGR piglet brain on both P1 and P4 compared with NG piglets. These increases were associated with a change in activation state, as noted by altered glial morphology. This inflammatory state was further evident with increased expression levels of proinflammatory cytokines (interleukin-1β, tumour necrosis factor-α) and decreased levels of anti-inflammatory cytokines (interleukin-4 and -10) observed in the IUGR piglet brains.

CONCLUSIONS

These findings suggest that the piglet model of IUGR displays the characteristic neuropathological outcomes of neuronal and white matter impairment similar to those reported in the IUGR human brain. The activated glial morphology and elevated proinflammatory cytokines is indicative of an inflammatory response that may be associated with neuronal damage and white matter disruption. These findings support the use of the piglet as a pre-clinical model for studying mechanisms of altered neurodevelopment in the IUGR newborn.

Accuracy of Transient Elastography Data Combined With APRI in Detection and Staging of Liver Disease in Pediatric Patients With Cystic Fibrosis

BACKGROUND & AIMS

Liver disease develops in 15%-72% of patients with cystic fibrosis, and 5%-10% develop cirrhosis or portal hypertension, usually during childhood. Transient elastography (TE) is a noninvasive method to measure liver stiffness. We aimed to validate its accuracy in detection of liver disease and assessment of fibrosis in children with cystic fibrosis.

METHODS

We performed a cross-sectional study to evaluate the accuracy of TE in analysis of liver disease in 160 consecutive children who presented with cystic fibrosis (9.0 ± 0.4 years old, 53% male) at a tertiary referral pediatric center in Australia, from 2011 through 2016. Patients were classified as having cystic fibrosis-associated liver disease (CFLD) or cystic fibrosis without liver disease (CFnoLD) based on clinical, biochemical, and imaging features. Fibrosis severity was determined from histologic analysis of dual-pass liver biopsies from children with CFLD, as the reference standard. Data from healthy children without cystic fibrosis (n = 64, controls) were obtained from a separate study. Liver stiffness measurements (LSMs) were made by Fibroscan analysis, using the inter-quartile range/median ≤30% of 10 valid measurements. Children with macronodularity or portal hypertension with heterogeneous changes on ultrasound without available biopsy were assigned to the category of stage F3-F4 fibrosis.

RESULTS

LSM was made reliably in 86% of children; accuracy increased with age. LSMs were significantly higher in children with CFLD (10.7 ± 2.4 kPa, n = 33) than with CFnoLD (4.6 ± 0.1 kPa, n = 105) (P < .0001) or controls (4.1 ± 0.1kPa) (P < .0001); LSMs were higher in children with CFnoLD than controls (P < .05). At a cut-off value of 5.55kPa, LSM identified children with CFLD with an area under the receiver operating characteristic (AUROC) curve of 0.82, 70% sensitivity, and 82% specificity (P < .0001). Classification and regression tree models that combined LSM and aspartate aminotransferase to platelet ratio index (APRI) identified children with CFLD with an AUROC curve of 0.89, 87% sensitivity, and 74% specificity (odds ratio, 18.6). LSMs correlated with fibrosis stage in patients with CFLD (r = 0.67, P = .0001). A cut-off value of 8.7kPa differentiated patients with stage F3-F4 fibrosis from patients with stage F1-F2 fibrosis (AUROC, 0.87; 75% sensitivity; 100% specificity, P=.0002). The combination of LSMs and APRI improved the differentiation of patients with F3-F4 fibrosis vs F1-F2 fibrosis (AUROC, 0.92; 83% sensitivity; and 100% specificity (P < .01).

CONCLUSIONS

LSMs made by TE accurately detect liver disease in children with cystic fibrosis; diagnostic accuracy increases when LSMs are combined with APRI. LSMs also differentiate between children with cystic fibrosis with mild-moderate fibrosis vs advanced fibrosis.

A comprehensive analysis of MNG1, TCO1, fPTC, PTEN, TSHR, and TRKA in familial nonmedullary thyroid cancer: confirmation of linkage to TCO1

About 5% of nonmedullary thyroid cancer is familial. These familial nonmedullary thyroid cancer cases are characterized by an earlier age of onset, more aggressive phenotype, and in some families a high propensity to benign thyroid disease. Little is known about the genes conferring predisposition to nonmedullary thyroid cancer. Three loci have been identified through genetic linkage: MNG1 on 14q32, TCO1 on 19p13.2, and fPTC on 1p21. In addition to these putative genes, a number of loci represent candidate familial nonmedullary thyroid cancer predisposition genes by virtue of their involvement in sporadic disease (TRKA), their role in benign disease (TSHR), and because they underlie syndromes with a risk of nonmedullary thyroid cancer (PTEN). To evaluate the roles of MNG1, TCO1, fPTC, PTEN, TSHR, and TRKA in familial nonmedullary thyroid cancer, we have carried out a comprehensive mutation and linkage analysis of these genes in 22 families. One family was linked to chromosome 19q13.2, confirming that TCO1 underlies a subset of familial nonmedullary thyroid cancer. None of the families was linked to MNG1 or fPTC, and there was no evidence to support the roles of PTEN, TSHR, or TRKA. Familial nonmedullary thyroid cancer is an emerging clinical phenotype that is genetically heterogeneous, and none of the currently identified genes accounts for the majority of families.

Efficacy of post-insult minocycline administration to alter long-term hypoxia-ischemia-induced damage to the serotonergic system in the immature rat brain

Neuroinflammation is a key mechanism contributing to long-term neuropathology observed after neonatal hypoxia-ischemia (HI). Minocycline, a second-generation tetracycline, is a potent inhibitor of neuroinflammatory mediators and is successful for at least short-term amelioration of neuronal injury after neonatal HI. However the long-term efficacy of minocycline to prevent injury to a specific neuronal network, such as the serotonergic (5-hydroxytryptamine, 5-HT) system, is not known. In a post-natal day 3 (P3) rat model of preterm HI we found significant reductions in 5-HT levels, 5-HT transporter expression and numbers of 5-HT-positive dorsal raphé neurons 6 weeks after insult compared to control animals. Numbers of activated microglia were significantly elevated in the thalamus and dorsal raphé although the greatest numbers were observed in the thalamus. Brain levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also significantly elevated on P45 in the thalamus and frontal cortex. Post-insult administration of minocycline for 1 week (P3-P9) attenuated the P3 HI-induced increases in numbers of activated microglia and levels of TNF-α and IL-1β on P45 with concurrent changes in serotonergic outcomes. The parallel prevention of P3 HI-induced serotonergic changes suggests that inhibition of neuroinflammation within the first week after P3 HI injury was sufficient to prevent long-term neuroinflammation as well as serotonergic system damage still evident at 6 weeks. Thus early, post-insult administration of minocycline may target secondary neuroinflammation and represent a long-term therapy to preserve the integrity of the central serotonergic network in the preterm neonate.

Selective losses of brainstem catecholamine neurons after hypoxia-ischemia in the immature rat pup

Hypoxic-ischemic (HI) injury in the preterm neonate incurs numerous functional deficits, however little is known about the neurochemically-defined brain nuclei that may underpin them. Key candidates are the brainstem catecholamine neurons. Using an immature animal model, the postnatal day (P)-3 (P3) rat pup, we investigated the effects of HI on brainstem catecholamine neurons in the locus coeruleus, nucleus tractus solitarius (NTS), and ventrolateral medulla (VLM). On P21, we found that prior P3 HI significantly reduced numbers of catecholaminergic neurons in the locus coeruleus, NTS, and VLM. Only locus coeruleus A6, NTS A2, and VLM A1 noradrenergic neurons, but not NTS C2 and VLM C1 adrenergic neurons, were lost. There was also an associated reduction in dopamine-beta-hydroxylase-positive immunolabeling in the forebrain. These findings suggest neonatal HI can affect specific neurochemically-defined neuronal populations in the brainstem and that noradrenergic neurons are particularly vulnerable to HI injury.

Analysis of the CTLA4 gene in Swedish coeliac disease patients

BACKGROUND

A genetic susceptibility to coeliac disease is well established, involving HLA and non-HLA components. CTLA4 is an important regulator of T-cell function and some studies have suggested that sequence variation in the gene might be a determinant of disease susceptibility, although the evidence is conflicting.

METHODS

Sixty-two children with biopsy-proven coeliac disease attending a single centre in Sweden were studied. All were genotyped for presence of the HLA-DQA1*0501, B 1*0201 alleles. Those who carried the HLA-DQ heterodimer (58/62) were genotyped for the +49 (A/G) exon I polymorphism. The transmission disequilibrium test (TDT) was used to test for association between coeliac disease and the A allele. The entire CTLA4 gene was screened for other sequence variants using a combination of conformation-sensitive gel electrophoresis and direct sequencing.

RESULTS

A significant association between the exon I polymorphism and coeliac disease was observed (P = 0.02). No other sequence variants in CTLA4 were detected.

CONCLUSIONS

This study provides further evidence that variation in CTLA4 is a determinant of coeliac disease susceptibility. If not mediated through the +49 (A/G) dimorphism directly, then the effect is likely to be mediated through linkage disequilibrium.

Ibuprofen Treatment Reduces the Neuroinflammatory Response and Associated Neuronal and White Matter Impairment in the Growth Restricted Newborn

Intrauterine growth restriction (IUGR) is a condition where the fetus does not achieve optimal growth, commonly caused by placental insufficiency. The chronic decrease in blood flow restricts oxygen and nutrient supply to the fetus, which can damage numerous organ systems, with the fetal brain being particularly vulnerable. Although white matter and neuronal injury are evident in IUGR infants, the specific mechanisms underlying these changes are poorly understood. Inflammation is considered to be a main driver in exacerbating brain injury. Using a spontaneous piglet model of IUGR, we aim to determine whether administration of the anti-inflammatory drug ibuprofen will decrease inflammation at postnatal day 4 (P4). The treatment group received ibuprofen (20 mg/kg/day on day 1 and 10 mg/kg/day on days 2 and 3) in piglet formula during the morning feed each day and brains examined on P4. Markers of inflammation, apoptosis, cell proliferation, neuronal injury, and white matter injury were examined. Ibuprofen treatment ameliorated the increase in numbers of microglia and astrocytes in the parietal cortex and white matter tracts of the IUGR piglet brain on P4 as well as decreasing proinflammatory cytokines. Ibuprofen treatment prevented the reduction in apoptosis, neuronal cell counts, and myelin index in the IUGR piglets. Our findings demonstrate ibuprofen reduces the inflammatory response in the IUGR neonatal brain and concurrently reduces neuronal and white matter impairment.

Transient liver elastography in unsedated control children: Impact of age and intercurrent illness

AIM

Transient elastography (TE) is a rapid, non-invasive, reproducible assessment of liver fibrosis by liver stiffness measurement (LSM). Uncertainty remains regarding utility in children, unsedated and <6 years of age. The importance of general health at the time of study has not been addressed. We report our experience of TE in unsedated control children, impact of intercurrent illness and using new published reliability criteria.

METHODS

From April 2011 to March 2013, 173 studies were performed in unsedated, healthy control children and children with intercurrent illness without detectable liver disease presenting to the Royal Children's Hospital, Brisbane, Australia. LSM reliability was assessed using interquartile range/median (IQR/M ≤ 30%) of 10 valid measurements.

RESULTS

A total of 123 (F:M, 52:71) of 173 studies (71.1%) gave reliable results. In children 0-2 years reliability was 36%, and >2 years reliable results were obtained in ~80%. LSM increased with age; 0-2 years (3.5 ± 0.5 kPa), 3-5 years (3.8 ± 0.3 kPa) and 6-11 years (4.1 ± 0.2 kPa) with healthy older children 12-18 years similar to adults (4.5 ± 0.2 kPa). LSM did not vary with gender (female, 4.5 ± 0.2 vs. male, 4.8 ± 0.2 kPa). Children with intercurrent, non-hepatological illnesses had higher LSM (5.2 ± 0.2 kPa (range, 2.8-11.1 kPa)) compared to healthy children ((4.1 ± 0.1 kPa, range, 2.1-6.3 kPa); P = 0.0001).

CONCLUSIONS

TE in unsedated children is feasible from infancy but most reliable after 2 years. Intercurrent illness increases LSM; hence, study context is important when interpreting results.

Early evolution of glial morphology and inflammatory cytokines following hypoxic-ischemic injury in the newborn piglet brain

Neuroinflammation is a hallmark of hypoxic-ischemic injury and can be characterized by the activation of glial cells and the expression of inflammatory cytokines and chemokines. Interleukin (IL)-1β and tumor necrosis factor (TNF)α are among the best-characterized early response cytokines and are often expressed concurrently. Several types of central nervous system cells secrete IL-1β and TNFα, including microglia, astrocytes, and neurons, and these cytokines convey potent pro-inflammatory actions. Chemokines also play a central role in neuroinflammation by controlling inflammatory cell trafficking. Our aim was to characterise the evolution of early neuroinflammation in the neonatal piglet model of hypoxic-ischemic encephalopathy (HIE). Piglets (< 24 h old) were exposed to HI insult, and recovered to 2, 4, 8, 12 or 24H post-insult. Brain tissue from the frontal cortex and basal ganglia was harvested for assessment of glial cell activation profiles and transcription levels of inflammatory markers in HI piglets with comparison to a control group of newborn piglets. Fluorescence microscopy was used to observe microglia, astrocytes, neurons, degenerating neurons and possibly apoptotic cells, and quantitative polymerase chain reaction was used to measure gene expression of several cytokines and chemokines. HI injury was associated with microglial activation and morphological changes to astrocytes at all time points examined. Gene expression analyses of inflammation-related markers revealed significantly higher expression of pro-inflammatory cytokines tumor necrosis factor-α (TNFα) and interleukin 1 beta (IL-1β), chemokines cxc-chemokine motif ligand (CXCL)8 and CXCL10, and anti-inflammatory cytokine transforming growth factor (TGF)β in every HI group, with some region-specific differences noted. No significant difference was observed in the level of C-X-C chemokine receptor (CCR)5 over time. This high degree of neuroinflammation was associated with a reduction in the number of neurons in piglets at 12H and 24H in the frontal cortex, and the putamen at 12H. This reduction of neurons was not associated with increased numbers of degenerating neurons or potentially apoptotic cells. HI injury triggered a robust early neuroinflammatory response associated with a reduction in neurons in cortical and subcortical regions in our piglet model of HIE. This neuroinflammatory response may be targeted using novel therapeutics to reduce neuropathology in our piglet model of neonatal HIE.

Therapeutic potential to reduce brain injury in growth restricted newborns

Brain injury in intrauterine growth restricted (IUGR) infants is a major contributing factor to morbidity and mortality worldwide. Adverse outcomes range from mild learning difficulties, to attention difficulties, neurobehavioral issues, cerebral palsy, epilepsy, and other cognitive and psychiatric disorders. While the use of medication to ameliorate neurological deficits in IUGR neonates has been identified as warranting urgent research for several years, few trials have been reported. This review summarises clinical trials focusing on brain protection in the IUGR newborn as well as therapeutic interventions trialled in animal models of IUGR. Therapeutically targeting mechanisms of brain injury in the IUGR neonate is fundamental to improving long-term neurodevelopmental outcomes. Inflammation is a key mechanism in neonatal brain injury; and therefore an appealing target. Ibuprofen, an anti-inflammatory drug currently used in the preterm neonate, may be a potential therapeutic candidate to treat brain injury in the IUGR neonate. To better understand the potential of ibuprofen and other therapeutic agents to be neuroprotective in the IUGR neonate, long-term follow-up information of neurodevelopmental outcomes must be studied. Where agents such as ibuprofen are shown to be effective, have a good safety profile and are relatively inexpensive, they can be widely adopted and lead to improved outcomes.

Role of MC1R variants in uveal melanoma

Variants of the melanocortin-1 receptor (MC1R) gene have been linked to sun-sensitive skin types and hair colour, and may independently play a role in susceptibility to cutaneous melanoma. To assess the role of MC1R variants in uveal melanoma, we have analysed a cohort of 350 patients for the changes within the major region of the gene displaying sequence variation. Eight variants were detected - V60L, D84E, V92M, R151C, I155T, R160W, R163Q and D294H - 63% of these patients being hetero- or homozygous for at least one variant. Standard melanoma risk factor data were available on 119 of the patients. MC1R variants were significantly associated with hair colour (P=0.03) but not skin or eye colour. The frequency of the variants detected in the 350 patients was comparable with those in the general population, and comparison of the cumulative tumour distribution by age at diagnosis in carriers and noncarriers provided no evidence that MC1R variants confer an increased risk of uveal melanoma. We interpret the data as indicating that MC1R variants do not appear to be major determinants of susceptibility to uveal melanoma.

Disruption of raphé serotonergic neural projections to the cortex: a potential pathway contributing to remote loss of brainstem neurons following neonatal hypoxic-ischemic brain injury

Neuronal injury is a key feature of neonatal hypoxic-ischemic (HI) brain injury. However, the mechanisms underpinning neuronal losses, such as in the brainstem, are poorly understood. One possibility is that disrupted neural connections between the cortex and brainstem may compromise the survival of neuronal cell bodies in the brainstem. We investigated whether brainstem raphé serotonergic neurons that project to the cortex are lost after HI. We also tested if neuroinflammation has a role in disrupting brainstem raphé projections. Postnatal day 3 (P3) rats underwent unilateral carotid artery ligation followed by hypoxia (6% oxygen for 30 min). A retrograde tracer, choleratoxin b, was deposited in the motor cortex on P38. On P45 we found that retrogradely labelled neurons in the dorsal raphé dorsal, ventrolateral, interfascicular, caudal and ventral nuclei were lost after P3 HI. All retrogradely labelled neurons in the raphé nuclei were serotonergic. Numbers of retrogradely labelled neurons were also reduced in the ventromedial thalamus and basolateral amygdala. Minocycline treatment (45 mg/kg 2 h post-HI, 22.5 mg/kg daily P4-P9) attenuated losses of retrogradely labelled neurons in the dorsal raphé ventrolateral, interfascicular and ventral raphé nuclei, and the ventromedial thalamus. These results indicate that raphé neurons projecting to the cortex constitute a population of serotonergic neurons that are lost after P3 HI. Furthermore, neuroinflammation has a role in the disruption of raphé and thalamic neural projections. Future studies investigating the cellular mechanisms of axonal degeneration may reveal new targets for interventions to prevent neuronal losses after neonatal HI.

Electroencephalographic studies in growth-restricted and small-for-gestational-age neonates

Foetal growth restriction (FGR) and being born small for gestational age (SGA) are associated with neurodevelopmental delay. Early diagnosis of neurological damage is difficult in FGR and SGA neonates. Electroencephalography (EEG) has the potential as a tool for the assessment of brain development in FGR/SGA neonates. In this review, we analyse the evidence base on the use of EEG for the assessment of neonates with FGR or SGA. We found consistent findings that FGR/SGA is associated with measurable changes in the EEG that present immediately after birth and persist into childhood. Early manifestations of FGR/SGA in the EEG include changes in spectral power, symmetry/synchrony, sleep-wake cycling, and the continuity of EEG amplitude. Later manifestations of FGR/SGA into infancy and early childhood include changes in spectral power, sleep architecture, and EEG amplitude. FGR/SGA infants had poorer neurodevelopmental outcomes than appropriate for gestational age controls. The EEG has the potential to identify FGR/SGA infants and assess the functional correlates of neurological damage. IMPACT: FGR/SGA neonates have significantly different EEG activity compared to AGA neonates. EEG differences persist into childhood and are associated with adverse neurodevelopmental outcomes. EEG has the potential for early identification of brain impairment in FGR/SGA neonates.

Hypoxia-ischemia in the immature rodent brain impairs serotonergic neuronal function in certain dorsal raphé nuclei

Neonatal hypoxia-ischemia (HI) results in losses of serotonergic neurons in specific dorsal raphé nuclei. However, not all serotonergic raphé neurons are lost and it is therefore important to assess the function of remaining neurons in order to understand their potential to contribute to neurological disorders in the HI-affected neonate. The main objective of this study was to determine how serotonergic neurons, remaining in the dorsal raphé nuclei after neonatal HI, respond to an external stimulus (restraint stress). On postnatal day 3 (P3), male rat pups were randomly allocated to one of the following groups: (i) control + no restraint (n = 5), (ii) control + restraint (n = 6), (iii) P3 HI + no restraint (n = 5) or (iv) P3 HI + restraint (n = 7). In the two HI groups, rat pups underwent surgery to ligate the common carotid artery and were then exposed to 6% O₂ for 30 minutes. Six weeks after P3 HI, on P45, rats were subjected to restraint stress for 30 minutes. Using dual immunolabeling for Fos protein, a marker for neuronal activity, and serotonin (5-hydroxytrypamine; 5-HT), numbers of Fos-positive 5-HT neurons were determined in five dorsal raphé nuclei. We found that restraint stress alone increased numbers of Fos-positive 5-HT neurons in all five dorsal raphé nuclei compared to control animals. However, following P3 HI, the number of stress-induced Fos-positive 5-HT neurons was decreased significantly in the dorsal raphé ventrolateral, interfascicular and ventral nuclei compared with control animals exposed to restraint stress. In contrast, numbers of stress-induced Fos-positive 5-HT neurons in the dorsal raphé dorsal and caudal nuclei were not affected by P3 HI. These data indicate that not only are dorsal raphé serotonergic neurons lost after neonatal HI, but also remaining dorsal raphé serotonergic neurons have reduced differential functional viability in response to an external stimulus. Procedures were approved by the University of Queensland Animal Ethics Committee (UQCCR958/08/NHMRC) on February 27, 2009.

Effects of fetal growth restriction on the perinatal neurovascular unit and possible treatment targets

The neurovascular unit (NVU) within the brain is a multicellular unit that synergistically acts to maintain blood-brain barrier function and meet cerebral metabolic demand. Recent studies have indicated disruption to the NVU is associated with neuropathology in the perinatal brain. Infants with fetal growth restriction (FGR) are known to be at increased risk of neurodevelopmental conditions including motor, learning, and behavioural deficits. There are currently no neuroprotective treatments for these conditions. In this review, we analyse large animal studies examining the effects of FGR on the perinatal NVU. These studies show altered vascularity in the FGR brain as well as blood-brain barrier dysfunction due to underlying cellular changes, mediated by neuroinflammation. Neuroinflammation is a key mechanism associated with pathological effects in the FGR brain. Hence, targeting inflammation may be key to preserving the multicellular NVU and providing neuroprotection in FGR. A number of maternal and postnatal therapies with anti-inflammatory components have been investigated in FGR animal models examining targets for amelioration of NVU disruption. Each therapy showed promise by uniquely ameliorating the adverse effects of FGR on multiple aspects of the NVU. The successful implementation of a clinically viable neuroprotective treatment has the potential to improve outcomes for neonates affected by FGR. IMPACT: Disruption to the neurovascular unit is associated with neuropathology in fetal growth restriction. Inflammation is a key mechanism associated with neurovascular unit disruption in the growth-restricted brain. Anti-inflammatory treatments ameliorate adverse effects on the neurovascular unit and may provide neuroprotection.

Disruption to the 5-HT7 Receptor Following Hypoxia-Ischemia in the Immature Rodent Brain

It has become increasingly evident the serotonergic (5-hydroxytryptamine, 5-HT) system is an important central neuronal network disrupted following neonatal hypoxic-ischemic (HI) insults. Serotonin acts via a variety of receptor subtypes that are differentially associated with behavioural and cognitive mechanisms. The 5-HT₇ receptor is purported to play a key role in epilepsy, anxiety, learning and memory and neuropsychiatric disorders. Furthermore, the 5-HT₇ receptor is highly localized in brain regions damaged following neonatal HI insults. Utilising our well-established neonatal HI model in the postnatal day 3 (P3) rat pup we demonstrated a significant decrease in levels of the 5-HT₇ protein in the frontal cortex, thalamus and brainstem one week after insult. We also observed a relative decrease in both the cytosolic and membrane fractions of 5-HT₇. The 5-HT₇ receptor was detected on neurons throughout the cortex and thalamus, and 5-HT cell bodies in the brainstem. However we found no evidence of 5-HT₇ co-localisation on microglia or astrocytes. Moreover, minocycline treatment did not significantly prevent the HI-induced reductions in 5-HT₇. In conclusion, neonatal HI injury caused significant disruption to 5-HT₇ receptors in the forebrain and brainstem. Yet the use of minocycline to inhibit activated microglia, did not prevent the HI-induced changes in 5-HT₇ expression.

Blood Biomarkers in the Fetally Growth Restricted and Small for Gestational Age Neonate: Associations with Brain Injury

Fetal growth restriction (FGR) and small for gestational age (SGA) infants have increased risk of mortality and morbidity. Although both FGR and SGA infants have low birthweights for gestational age, a diagnosis of FGR also requires assessments of umbilical artery Doppler, physiological determinants, neonatal features of malnutrition, and in utero growth retardation. Both FGR and SGA are associated with adverse neurodevelopmental outcomes ranging from learning and behavioral difficulties to cerebral palsy. Up to 50% of FGR, newborns are not diagnosed until around the time of birth, yet this diagnosis lacks further indication of the risk of brain injury or adverse neurodevelopmental outcomes. Blood biomarkers may be a promising tool. Defining blood biomarkers indicating an infant's risk of brain injury would provide the opportunity for early detection and therefore earlier support. The aim of this review was to summarize the current literature to assist in guiding the future direction for the early detection of adverse brain outcomes in FGR and SGA neonates. The studies investigated potential diagnostic blood biomarkers from cord and neonatal blood or serum from FGR and SGA human neonates. Results were often conflicting with heterogeneity common in the biomarkers examined, timepoints, gestational age, and definitions of FGR and SGA used. Due to these variations, it was difficult to draw strong conclusions from the results. The search for blood biomarkers of brain injury in FGR and SGA neonates should continue as early detection and intervention is critical to improve outcomes for these neonates.