Intrauterine Growth Restriction Affects Cerebellar Granule Cells in the Developing Guinea Pig Brain.

Intrauterine growth restriction (IUGR) can lead to adverse neurodevelopmental sequelae in postnatal life. However, the effects of IUGR on the cerebellum are still to be fully elucidated. A major determinant of growth and development of the cerebellum is proliferation and subsequent migration of cerebellar granule cells. Our objective was to determine whether IUGR, induced by chronic placental insufficiency (CPI) in guinea pigs, results in abnormal cerebellar development due to deficits suggestive of impaired granule cell proliferation and/or migration. CPI was induced by unilateral ligation of the uterine artery at mid-gestation, producing growth-restricted (GR) foetuses at 52 and 60 days of gestation (dg), and neonates at 1 week postnatal age (term approx. 67 dg). Controls were from sham-operated animals. In GR foetuses compared with controls at 52 dg, the external granular layer (EGL) width and internal granular layer (IGL) area were similar. In GR foetuses compared with controls at 60 dg: (a) the EGL width was greater (p < 0.005); (b) the IGL area was smaller (p < 0.005); (c) the density of Ki67-negative (postmitotic) granule cells in the EGL was greater (p < 0.01); (d) the somal area of Purkinje cells was reduced (p < 0.005), and (e) the linear density of Bergmann glia was similar. The EGL width in GR foetuses at 60 dg was comparable to that of 52 dg control and GR foetuses. The pattern of p27-immunoreactivity in the EGL was the inverse of Ki67-immunoreactivity at both foetal ages; there was no difference between control and GR foetuses at either age in the width of p27-immunoreactivity, or in the percentage of the EGL width that it occupied. In the molecular layer of GR neonates compared with controls there was an increase in the areal density of granule cells (p < 0.05) and in the percentage of migrating to total number of granule cells (p < 0.01) at 1 week but not at 60 dg (p > 0.05). Thus, we found no specific evidence that IUGR affects granule cell proliferation, but it alters the normal program of migration to the IGL and, in addition, the development of Purkinje cells. Such alterations will likely affect the development of appropriate circuitry and have implications for cerebellar function.

A new neonatal cortical and subcortical brain atlas: the Melbourne Children's Regional Infant Brain (M-CRIB) atlas.

Investigating neonatal brain structure and function can offer valuable insights into behaviour and cognition in healthy and clinical populations; both at term age, and longitudinally in comparison with later time points. Parcellated brain atlases for adult populations are readily available, however warping infant data to adult template space is not ideal due to morphological and tissue differences between these groups. Several parcellated neonatal atlases have been developed, although there remains strong demand for manually parcellated ground truth data with detailed cortical definition. Additionally, compatibility with existing adult atlases is favourable for use in longitudinal investigations. We aimed to address these needs by replicating the widely-used Desikan-Killiany (2006) adult cortical atlas in neonates. We also aimed to extend brain coverage by complementing this cortical scheme with basal ganglia, thalamus, cerebellum and other subcortical segmentations. Thus, we have manually parcellated these areas volumetrically using high-resolution neonatal T2-weighted MRI scans, and initial automated and manually edited tissue classification, providing 100 regions in all. Linear and nonlinear T2-weighted structural templates were also generated. In this paper we provide manual parcellation protocols, and present the parcellated probability maps and structural templates together as the Melbourne Children's Regional Infant Brain (M-CRIB) atlas.

Environmental enrichment delays limbic epileptogenesis and restricts pathologic synaptic plasticity.

OBJECTIVE: Environmental exposures impart powerful effects on vulnerability to many brain diseases, including epilepsy. Mesial temporal lobe epilepsy (MTLE) is a common form of epilepsy, and it is often accompanied by neuropsychiatric comorbidities. This study tests the hypothesis that environmental enrichment (EE) confers antiepileptogenic, psychoprotective, and neuroprotective effects in the amygdala kindling model of MTLE, and explores potential neurobiologic mechanisms. METHODS: At weaning, male Wistar rats were allocated into either EE (large cages containing running wheels and toys; n = 43) or standard housing (SH; standard laboratory cages; n = 39) conditions. At P56, a bipolar electrode was implanted into the left amygdala, and rats underwent rapid amygdala kindling until experiencing five class V seizures (Racine scale, fully kindled). The elevated plus maze was used to assess anxiety. Postmortem histologic and molecular analyses investigated potential biologic mediators of effects. RESULTS: EE significantly delayed kindling epileptogenesis, with EE rats requiring a significantly greater number of kindling stimulations to reach a fully kindled state compared to SH rats (p < 0.05). EE and kindling both reduced anxiety (p < 0.05). Timm's staining revealed significant reductions in aberrant mossy fiber sprouting in EE rats (p < 0.05), and these effects of EE were accompanied by reduced expression of TrkB and CRH genes. SIGNIFICANCE: We identify beneficial effects of EE on vulnerability to limbic epileptogenesis and anxiety, and identify reduced pathologic neuroplasticity and plasticity-related gene expression as potential underlying mechanisms. Enhanced environmental stimulation represents a potential antiepileptogenic strategy that might also mitigate the common psychiatric comorbidities of MTLE.

A qualitative study examining healthcare managers and providers' perspectives on participating in primary care implementation research.

BACKGROUND: Primary care reforms should be supported by high-quality evidence across the entire life cycle of research. Front-line healthcare providers play an increasing role in implementation research. We recently evaluated two interventions for people with type 2 diabetes (T2D) in partnership with four Primary Care Networks (PCNs) in Alberta, Canada. Here, we report healthcare professionals perspectives on participating in primary care implementation research. METHODS: Guided by the RE-AIM framework, we collected qualitative data before, during, and after both interventions. We conducted 34 in-person or telephone interviews with 17 individual PCN professionals. We used content analysis to identify emerging codes and concepts. RESULTS: Two major themes emerged from the data. First, healthcare managers were eager to conduct implementation research in a primary care setting. Second, regardless of willingness to conduct research, there were challenges to implementing experimental study designs for both interventions. PCN professionals presumed the interventions were better than usual care, expressed role conflict, and reported administrative burdens related to research participation. Perceptions of patient vulnerability and an obligation to intervene exacerbated these issues. CONCLUSIONS: Healthcare professionals with limited practical research experience might not foresee the challenges in implementing experimental study designs in primary care settings to generate high-quality evidence. These issues are intensified when healthcare professionals perceive target patient populations as vulnerable and in need of intervention based on the presenting illness. Possible solutions include further research training, involving healthcare professionals in study design development, and using non-clinical staff to conduct research activities, particularly among acutely unwell patient populations.

Intrauterine Growth Restriction: Effects on Neural Precursor Cell Proliferation and Angiogenesis in the Foetal Subventricular Zone.

Exposure to adverse prenatal factors can result in abnormal brain development, contributing to the aetiology of several neurological disorders. Intrauterine insults could occur during neurogenesis and gliogenesis, disrupting these events. Here we investigate the effects of chronic placental insufficiency (CPI) on cell proliferation and the microenvironment in the subventricular zone (SVZ). At 30 days of gestation (DG; term ∼67 DG), CPI was induced in pregnant guinea pigs via unilateral uterine artery ligation to produce growth-restricted (GR) foetuses (n = 7); controls (n = 6) were from the unoperated horn. At 60 DG, foetal brains were stained immunohistochemically to identify proliferating cells (Ki67), immature neurons (polysialylated neuronal cell adhesion molecule), astrocytes (glial fibrillary acidic protein), microglia (ionised calcium-binding adaptor molecule-1, Iba-1) and the microvasculature (von Willebrand factor) in the SVZ. There was no overall difference (p > 0.05) in the total number of Ki67-immunoreactive (IR) cells, the percentage of SVZ occupied by blood vessels or the density of Iba-1-IR microglia in control versus GR foetuses. However, regression analysis across both groups revealed that both the number of Ki67-IR cells and the percentage of SVZ occupied by blood vessels in the ventral SVZ were negatively correlated (p < 0.05) with brain weight. Furthermore, in the SVZ (dorsal and ventral) the density of blood vessels positively correlated (p < 0.05) with the number of Ki67-IR cells. Double-labelling immunofluorescence suggested that the majority of proliferating cells were likely to be neural precursor cells. Thus, we have demonstrated an association between angiogenesis and neurogenesis in the foetal neurogenic niche and have identified a window of opportunity for the administration of trophic support to enhance a neuroregenerative response.

Impact of daily high-dose caffeine exposure on developing white matter of the immature ovine brain.

BACKGROUND: Caffeine is widely used to treat apnea of prematurity, but the standard dosing regimen is not always sufficient to prevent apnea. Before higher doses of caffeine can be used, their effects on the immature brain need to be carefully evaluated. Our aim was to determine the impact of daily high-dose caffeine administration on the developing white matter of the immature ovine brain. METHODS: High-dose caffeine (25 mg/kg caffeine base loading dose; 20 mg/kg daily maintenance dose; n = 9) or saline (n = 8) were administered to pregnant sheep from 0.7 to 0.8 of term, equivalent to approximately 27-34 wk in humans. At 0.8 of term, the white and gray matter were assessed histologically and immunohistochemically. RESULTS: Daily caffeine administration led to peak caffeine concentration of 32 mg/l in fetal plasma at 1 h, followed by a gradual decline, with no effects on mean arterial pressure and heart rate. Initial caffeine exposure led to transient, mild alkalosis in the fetus but did not alter oxygenation. At necropsy, there was no effect of daily high-dose caffeine on brain weight, oligodendrocyte density, myelination, axonal integrity, microgliosis, astrogliosis, apoptosis, or neuronal density. CONCLUSION: Daily high-dose caffeine administration does not appear to adversely affect the developing white matter at the microstructural level.

Impact of levosimendan on brain injury patterns in a lamb model of infant cardiopulmonary bypass.

BACKGROUND: The effects of levosimendan (Levo) on injury patterns in the immature brain following cardiopulmonary bypass (CPB) are unknown. METHODS: Eighteen 3- to 4-wk-old anesthetized lambs, instrumented with vascular catheters and aortic and right carotid artery flow probes, were allocated to non-CPB, CPB, or CPB+Levo groups (each n = 6). After 120 min CPB with 90 min aortic cross-clamp, CPB animals received dopamine, and CPB+Levo animals both dopamine and Levo, for 4 h. All lambs then underwent brain magnetic resonance imaging, followed by postmortem brain perfusion fixation for immunohistochemical studies. RESULTS: In CPB lambs, aortic (P < 0.05) and carotid artery (P < 0.01) blood flows fell by 29 and 30%, respectively, between 2 and 4 h after cross-clamp removal but were unchanged in the CPB+Levo group. No brain injury was detectable with magnetic resonance imaging in either CPB or CPB+Levo lambs. However, on immunohistochemical analysis, white matter astrocyte density of both groups was higher than in non-CPB lambs (P < 0.05), while white matter microglial density was higher (P < 0.05), but markers of cortical oxidative stress were less prevalent in CPB+Levo than CPB lambs. CONCLUSION: While Levo prevented early postoperative falls in cardiac output and carotid artery blood flow in a lamb model of infant CPB, this was associated with heterogeneous neuroglial activation and manifestation of markers of oxidative stress.

Hypometabolism precedes limbic atrophy and spontaneous recurrent seizures in a rat model of TLE.

PURPOSE: Temporal hypometabolism on fluorodeoxyglucose positron emission tomography (FDG-PET) is a common finding in patients with drug-resistant temporal lobe epilepsy (TLE). The pathophysiology underlying the hypometabolism, including whether it reflects a primary epileptogenic process, or whether it occurs later as result of limbic atrophy or as a result of chronic seizures, remains unknown. This study aimed to investigate the ontologic relationship among limbic atrophy, histological changes, and hypometabolism in rats. METHODS: Serial in vivo imaging with FDG-PET and volumetric magnetic resonance imaging (MRI) was acquired before and during the process of limbic epileptogenesis resulting from kainic acid-induced status epilepticus in the rat. The imaging data were correlated with histologic measures of cell loss, and markers of astrogliosis (glial fibrillary acid protein [GFAP]), synaptogenesis (synaptophysin), glucose transporter 1 (Glut1) and energy metabolism (cytochrome oxidase C), on brains of the animals following the final imaging point. KEY FINDINGS: Hippocampal hypometabolism on FDG-PET was found to be present 24 h following status epilepticus, tending to lessen by 1 week and then become more marked again following the onset of spontaneous seizures. Atrophy of limbic structures was evident from 7 days post-SE, becoming progressively more marked on serial MRI over subsequent weeks. No relationship was observed between the severity of MRI-detected atrophy or CA1 pyramidal cell loss and the degree of the hypometabolism on FDG-PET. However, an inverse relationship was observed between hypometabolism and increased expression of the Glut1 and synaptophysin in the hippocampus. SIGNIFICANCE: These findings demonstrate that hypometabolism occurs early in the processes of limbic epileptogenesis and is not merely a consequence of pyramidal cell loss or the progressive atrophy of limbic brain structures that follow. The hypometabolism may reflect cellular mechanisms occurring early during epileptogenesis in addition to any effects of the subsequent recurrent spontaneous seizures.

Repeated courses of antenatal corticosteroids have adverse effects on aspects of brain development in naturally delivered baboon infants.

INTRODUCTION: Repeated courses of antenatal steroids in women at risk of preterm delivery have beneficial effects on lung maturation, but concern exists about the effects on brain development. We aimed to determine whether repeated courses of corticosteroids increased the risk of neuropathology as compared with single courses or no treatment. METHODS: Single-course animals received a 6-mg dose of steroids at 123 and 124 d of gestation (dg; term, 185 dg; n = 6). Repeated-course animals received additional doses at 137 and 138 dg (n = 7). Controls received no steroids (n = 5). Baboons delivered naturally at term and necropsy was performed. Brains were assessed histologically for parameters of development and neuropathology. RESULTS: Body weights did not differ between the groups (P > 0.05); neither did brain/body weight ratio. Density of glial fibrillary acidic protein (GFAP)-immunoreactive (IR) astrocytes in white matter (WM) was increased in the single- (P < 0.05) and repeated-course (P < 0.01) groups as compared with controls. Density of myelin basic protein (MBP)-IR oligodendrocytes was reduced in the repeated-course animals as compared with both the control and single-course groups (P < 0.05); oligodendrocyte transcription factor 2 (Olig2)-IR showed no difference between groups. DISCUSSION: Repeated courses of antenatal corticosteroids have effects on myelination in the developing nonhuman primate brain, which should be taken into account when determining a dosing regimen.

MR imaging correlates of white-matter pathology in a preterm baboon model.

INTRODUCTION: Cerebral white-matter (WM) abnormalities on magnetic resonance imaging (MRI) correlate with neurodevelopmental disability in infants born prematurely. RESULTS: Quantitative histological measures of WM and ventricular volumes correlated with qualitative MRI scores of WM volume loss and ventriculomegaly. Diffuse astrocytosis was associated with signal abnormality on T(2)-weighted imaging and higher apparent diffusion coefficient in WM. Loss of oligodendrocytes was associated with lower relative anisotropy characterized by higher radial diffusivity values. The relationship between histopathology and MRI abnormalities was more pronounced in animals in the 28 d model, equivalent to the term human infant. DISCUSSION: MRI reflects microstructural and anatomical abnormalities that are characteristic of WM injury in the preterm brain, and these changes are more evident on MRI at term-equivalent postmenstrual age. METHODS: We assessed the histopathological correlates of MRI abnormalities in a baboon model of premature birth. Baboons were delivered at 125 d of gestation (dg, term ~185 dg) and maintained in an animal intensive care unit for 14 (n = 26) or 28 d (n = 17). Gestational control animals were delivered at 140 dg (n = 9) or 153 dg (n = 4). Cerebral WM in fixed brains was evaluated using MRI, diffusion tensor imaging (DTI), and histopathology.

Interventions to improve influenza and pneumococcal vaccination rates among community-dwelling adults: a systematic review and meta-analysis.

PURPOSE: Influenza and pneumococcal vaccination rates remain below national targets. We systematically reviewed the effectiveness of quality improvement interventions for increasing the rates of influenza and pneumococcal vaccinations among community-dwelling adults. METHODS: We included randomized and nonrandomized studies with a concurrent control group. We estimated pooled odds ratios using random effects models, and used the Downs and Black tool to assess the quality of included studies. RESULTS: Most studies involved elderly primary care patients. Interventions were associated with improvements in the rates of any vaccination (111 comparisons in 77 studies, pooled odds ratio [OR] = 1.61, 95% CI, 1.49-1.75), and influenza (93 comparisons, 65 studies, OR = 1.46, 95% CI, 1.35-1.57) and pneumococcal (58 comparisons, 35 studies, OR = 2.01, 95% CI, 1.72-2.3) vaccinations. Interventions that appeared effective were patient financial incentives (influenza only), audit and feedback (influenza only), clinician reminders, clinician financial incentives (influenza only), team change, patient outreach, delivery site changes (influenza only), clinician education (pneumococcus only), and case management (pneumococcus only). Patient outreach was more effective if personal contact was involved. Team changes were more effective where nurses administered influenza vaccinations independently. Heterogeneity in some pooled odds ratios was high, however, and funnel plots showed signs of potential publication bias. Study quality varied but was not associated with outcomes. CONCLUSIONS: Quality improvement interventions, especially those that assign vaccination responsibilities to nonphysician personnel or that activate patients through personal contact, can modestly improve vaccination rates in community-dwelling adults. To meet national policy targets, more-potent interventions should be developed and evaluated.

Controlled trial of a collaborative primary care team model for patients with diabetes and depression: rationale and design for a comprehensive evaluation.

BACKGROUND: When depression accompanies diabetes, it complicates treatment, portends worse outcomes and increases health care costs. A collaborative care case-management model, previously tested in an urban managed care organization in the US, achieved significant reduction of depressive symptoms, improved diabetes disease control and patient-reported outcomes, and saved money. While impressive, these findings need to be replicated and extended to other healthcare settings. Our objective is to comprehensively evaluate a collaborative care model for comorbid depression and type 2 diabetes within a Canadian primary care setting. METHODS/DESIGN: We initiated the TeamCare model in four Primary Care Networks in Northern Alberta. The intervention involves a nurse care manager guiding patient-centered care with family physicians and consultant physician specialists to monitor progress and develop tailored care plans. Patients eligible for the intervention will be identified using the Patient Health Questionnaire-9 as a screen for depressive symptoms. Care managers will then guide patients through three phases: 1) improving depressive symptoms, 2) improving blood glucose, blood pressure and cholesterol, and 3) improving lifestyle behaviors. We will employ the RE-AIM framework for a comprehensive and mixed-methods approach to our evaluation. Effectiveness will be assessed using a controlled "on-off" trial design, whereby eligible patients would be alternately enrolled in the TeamCare intervention or usual care on a monthly basis. All patients will be assessed at baseline, 6 and 12 months. Our primary analyses will be based on changes in two outcomes: depressive symptoms, and a multivariable, scaled marginal model for the combined outcome of global disease control (i.e., A1c, systolic blood pressure, LDL cholesterol). Our planned enrolment of 168 patients will provide greater than 80% power to observe clinically important improvements in all measured outcomes. Direct costing of all intervention components and measurement of all health care utilization using linked administrative databases will be used to determine the cost-effectiveness of the intervention relative to usual care. DISCUSSION: Our comprehensive evaluation will generate evidence to reliability, effectiveness and sustainability of this collaborative care model for patients with chronic diseases and depression. TRIALS REGISTRATION: Clinicaltrials.gov Identifier: NCT01328639.

Daily ethanol exposure during late ovine pregnancy: physiological effects in the mother and fetus in the apparent absence of overt fetal cerebral dysmorphology.

High levels of ethanol (EtOH) consumption during pregnancy adversely affect fetal development; however, the effects of lower levels of exposure are less clear. Our objectives were to assess the effects of daily EtOH exposure (3.8 USA standard drinks) on fetal-maternal physiological variables and the fetal brain, particularly white matter. Pregnant ewes received daily intravenous infusions of EtOH (0.75 g/kg maternal body wt over 1 h, 8 fetuses) or saline (8 fetuses) from 95 to 133 days of gestational age (DGA; term ∼145 DGA). Maternal and fetal arterial blood was sampled at 131-133 DGA. At necropsy (134 DGA) fetal brains were collected for analysis. Maternal and fetal plasma EtOH concentrations reached similar maximal concentration (∼0.11 g/dl) and declined at the same rate. EtOH infusions produced mild reductions in fetal arterial oxygenation but there were no changes in maternal oxygenation, maternal and fetal Pa(CO(2)), or in fetal mean arterial pressure or heart rate. Following EtOH infusions, plasma lactate levels were elevated in ewes and fetuses, but arterial pH fell only in ewes. Fetal body and brain weights were similar between groups. In three of eight EtOH-exposed fetuses there were small subarachnoid hemorrhages in the cerebrum and cerebellum associated with focal cortical neuronal death and gliosis. Overall, there was no evidence of cystic lesions, inflammation, increased apoptosis, or white matter injury. We conclude that daily EtOH exposure during the third trimester-equivalent of ovine pregnancy has modest physiological effects on the fetus and no gross effects on fetal white matter development.

Caffeine and brain development in very preterm infants.

OBJECTIVE: Caffeine improves neurological outcome in very preterm infants, but the mechanisms responsible for this neurological benefit are unknown. The objective of this study was to assess whether caffeine influenced brain macro- or microstructural development in preterm infants. METHODS: Seventy preterm infants <1,251 g birthweight randomly allocated to either caffeine (n = 33) or placebo (n = 37) underwent brain magnetic resonance imaging (MRI) at term-equivalent age; white and gray matter abnormalities were qualitatively scored, global and regional brain volumes were measured, and white matter microstructure was evaluated using diffusion-weighted imaging. RESULTS: There were no significant differences between the groups in the extent of white matter or gray matter abnormality, or in global or regional brain volumes. In contrast, although only available in 28 children, caffeine exposure was associated with reductions in the apparent diffusion coefficient, and radial and axial diffusivity with the greatest impact in the superior brain regions. The alterations in diffusion measures were not mediated by lowering the rate of lung injury, known as bronchopulmonary dysplasia. INTERPRETATION: These diffusion changes are consistent with improved white matter microstructural development in preterm infants who received caffeine.

The effects of postnatal estrogen therapy on brain development in preterm baboons.

OBJECTIVE: Estrogen receptors are present within the fetal brain, suggesting that estrogens may exert an influence on cerebral development. Loss of placentally derived estrogen in preterm birth may impair development. STUDY DESIGN: Baboons were delivered at 125 days of gestation (term approximately 185 days), randomly allocated to receive estradiol (n = 10) or placebo (n = 8), and ventilated for 14 days. Brains were assessed for developmental and neuropathological parameters. RESULTS: Body and brain weights were not different between groups, but the brain/body weight ratio was increased (P < .05) in estradiol-treated animals. There were no differences (P > .05) between groups in any neuropathological measure in either the forebrain or cerebellum. There were no intraventricular hemorrhages; 1 estradiol animal displayed ectactic vessels in the subarachnoid space. CONCLUSION: Brief postnatal estradiol administration to primates does not pose an increased risk of injury or impaired brain development.

Ibuprofen treatment for closure of patent ductus arteriosus is not associated with increased risk of neuropathology.

Ibuprofen is an effective pharmacological intervention for closure of a patent ductus arteriosus (PDA) in preterm infants and is an alternative to surgical ligation; however, it is not certain whether ibuprofen treatment is associated with adverse effects on the brain. Therefore, this study examined neuropathological outcomes of ibuprofen therapy for a PDA. Fetal baboons were delivered at 125 d of gestation (dg; term ∼185 dg) by caesarean section, given surfactant, and ventilated for 14 d with positive pressure ventilation (PPV). Baboons were randomly allocated to receive either ibuprofen (PPV+ ibuprofen, n = 8) or no therapy (PPV, n = 5). Animals were killed on day 14 and brains assessed for cerebral growth, development, and neuropathology. Body and brain weights, the total volume of the brain, and the surface folding index (measure of brain growth) were not different (p > 0.05) between PPV+ ibuprofen-treated and PPV animals. There was no difference (p > 0.05) in the number of myelin basic protein-immunoreactive (IR) oligodendrocytes, glial fibrillary acid protein-IR astrocytes, or Iba1-IR macrophages/microglia in the forebrain. No overt cerebellar alterations were observed in either group. Ibuprofen treatment for PDA closure in the preterm baboon neonate is not associated with any increased risk of neuropathology or alterations to brain growth and development.

Cerebellar development in a baboon model of preterm delivery: impact of specific ventilatory regimes.

Premature infants now have an improved chance of survival, but the impact of respiratory therapies on the brain, particularly the cerebellum, remains unclear. We examined the effects of early nasal continuous positive airway pressure (EnCPAP) ventilation and delayed (Dn) CPAP on the development of the cerebellum in prematurely delivered baboons. The baboons were delivered at 125 +/- 2days of gestation and ventilated for 28 days with either EnCPAP commencing at 24 hours (n = 5) or DnCPAP commencing at 5 days (n = 5). Gestational controls (n = 4) were delivered at 153 days. Cerebella were assessed histologically, and an ontogeny study (90 days to term) was performed to establish values for key cerebellar developmental indicators. Cerebellar weight was reduced in DnCPAP but not EnCPAP animals versus controls; cerebellar/total brain weight ratio was increased in EnCPAP (p < 0.05) versus control and DnCPAP animals. There was no overt damage in the cerebella of any animals, but a microstructural alteration index based on morphological developmental parameters and microglial immunoreactivity was increased in both prematurely delivered cohorts versus controls (p < 0.001) and was higher in DnCPAP than EnCPAP animals (p < 0.05). These results indicate that respiratory regimens can influence cerebellar development and that early compared with delayed extubation to nCPAP seems to be beneficial.

Developmental profile of erythropoietin and its receptor in guinea-pig retina.

Evidence suggests that endogenous erythropoietin (EPO) is involved in the development of the central nervous system; however, its role in retinal development is yet to be determined. In this study, we have used fluorescence immunohistochemistry to localise EPO and its receptor (EPOR) in the developing and mature retina of the guinea-pig, a species in which retinal development is similar to that in humans. EPO immunoreactivity (IR) was observed in ganglion cells from 25 days of gestation (dg; term approximately 67 dg), and in the inner and outer plexiform layers and in horizontal cells by 40 dg. EPO-IR persisted in all of these structures into adulthood. Müller cells also displayed EPO-IR, which was seen in the radial processes and endfeet at 40 dg and in the cytoplasm by 50 dg. IR in these cells was particularly intense and appeared to increase with age. EPOR-IR was found in all ages examined; it was detected in ganglion cells at 25 dg and, from 30 dg onwards, was localised on, and adjacent to, the cell surface membrane. The distribution of EPOR-IR became increasingly widespread during gestation and, by 50 dg, EPOR-IR was detectable on the majority of retinal somal membranes. This localisation persisted in the postnatal and adult retina. Therefore, IR for EPO and its receptor is present in the guinea-pig retina from as early as 25 dg, when retinal layers are forming, and persists throughout postnatal development. This suggests that EPO plays a role both in retinal development and in the maintenance of the adult retina.

Investigating structural and biochemical correlates of ganglion cell dysfunction in streptozotocin-induced diabetic rats.

The aim of this study was to determine whether inner retinal dysfunction in diabetic rats is correlated with structural and/or biochemical changes in the retina and optic nerve. Using the electroretinogram (ERG; -5.83 to 1.28 log cd.s.m(-2)) retinal function (photoreceptor, bipolar, amacrine and ganglion cell components) was measured in control (n=13; citrate buffer) and diabetic (n=13; streptozotocin, STZ, 50 mg kg(-1)) rats, 12 weeks following treatment. Retinae and optic nerves were analyzed for structural changes and retinae were assessed for alterations in growth factor/cytokine expression using quantitative real-time PCR. We found that phototransduction efficiency was reduced 12 weeks after STZ-induced diabetes (-30%), leading to reduced amplitude of ON-bipolar (-18%) and amacrine cell (-29%) dominated responses; ganglion cell dysfunction (-84%) was more profound. In the optic nerve, nerve fascicle area and myelin sheath thickness were reduced (p<0.05), whereas the ratio of blood vessels and connective tissue to total nerve cross-sectional area was increased (p<0.05) in diabetic compared to control rats. In the retina, connective tissue growth factor (CTGF), transforming growth factor beta, type 2 receptor (TGFbeta-r2) mRNA and platelet-derived growth factor B (PDGF-B) mRNA were increased (p<0.035). Reduced ganglion cell function was correlated with increased CTGF and TGFbeta-r2, but not PDGF-B mRNA. In summary, the ganglion cell component exhibited the greatest level of dysfunction within the ERG components examined after 12 weeks of STZ-induced diabetes; the level correlated with increased CTGF and TGFbeta-r2 mRNA, but not with gross morphological changes in the retina or optic nerve.

High-frequency oscillatory ventilation is not associated with increased risk of neuropathology compared with positive pressure ventilation: a preterm primate model.

High-frequency oscillatory ventilation (HFOV) may improve pulmonary outcome in very preterm infants, but the effects on the brain are largely unknown. We hypothesized that early prolonged HFOV compared with low volume positive pressure ventilation (LV-PPV) would not increase the risk of delayed brain growth or injury in a primate model of neonatal chronic lung disease. Baboons were delivered at 127 +/- 1 d gestation (dg; term approximately 185 dg), ventilated for 22-29 d with either LV-PPV (n = 6) or HFOV (n = 5). Gestational controls were delivered at 153 dg (n = 4). Brains were assessed using quantitative histology. Body, brain, and cerebellar weights were lower in both groups of prematurely delivered animals compared with controls; the brain to body weight ratio was higher in HFOV compared with LV-PPV, and the surface folding index was lower in the LV-PPV compared with controls. In both ventilated groups compared with controls, there was an increase in astrocytes and microglia and a decrease in oligodendrocytes (p < 0.05) in the forebrain and a decrease in cerebellar granule cell proliferation (p < 0.01); there was no difference between ventilated groups. LV-PPV and HFOV ventilation in prematurely delivered animals is associated with decreased brain growth and an increase in subtle neuropathologies; HFOV may minimize adverse effects on brain growth.