Publications by authors named "Marianne Thoresen"

120 Publications

Morphine and fentanyl exposure during therapeutic hypothermia does not impair neurodevelopment.

EClinicalMedicine 2021 Jun 5;36:100892. Epub 2021 Jun 5.

Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

Background: Hypothermia-treated and intubated infants with moderate or severe hypoxic-ischemic encephalopathy (HIE) usually receive morphine for sedation and analgesia (SA) during therapeutic hypothermia (TH) and endotracheal ventilation. Altered drug pharmacokinetics in this population increases the risk of drug accumulation. Opioids are neurotoxic in preterm infants. In term infants undergoing TH, the long-term effects of morphine exposure are unknown. We examined the effect of opioid administration during TH on neurodevelopmental outcome and time to extubation after sedation ended.

Methods: In this prospectively collected population-based cohort of 282 infants with HIE treated with TH (2007-2017), the cumulative opioid dose of morphine and equipotent fentanyl (10-60 µg/kg/h) administered during the first week of life was calculated. Clinical outcomes and concomitant medications were also collected. Of 258 survivors, 229 underwent Bayley-3 neurodevelopmental assessments of cognition, language and motor function at 18-24 months. Multivariate stepwise linear regression analysis was used to examine the relation between cumulative opioid dose and Bayley-3 scores. Three severity-groups (mild-moderate-severe) were stratified by early (<6 h) amplitude-integrated electroencephalography (aEEG) patterns.

Findings: The cumulative dose of opioid administered as SA during TH was median (IQR) 2121 µg/kg (1343, 2741). Time to extubation was independent of SA dose ( > 0.2). There was no significant association between cumulative SA dose and any of the Bayley-3 domains when analysing the entire cohort or any of the aEEG severity groups.

Interpretation: Higher cumulative opioid doses in TH-treated infants with HIE was not associated with worse Bayley-3 scores at 18-24 months of age.

Funding: The Bristol cooling program was funded by the Children's Medical Research Charity SPARKS managing donations for our research from the UK and US, the UK Moulton Foundation, the Lærdal Foundation for Acute Medicine in Norway and the Norwegian Research Council (JKG).
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http://dx.doi.org/10.1016/j.eclinm.2021.100892DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8257990PMC
June 2021

MRI combined with early clinical variables are excellent outcome predictors for newborn infants undergoing therapeutic hypothermia after perinatal asphyxia.

EClinicalMedicine 2021 Jun 17;36:100885. Epub 2021 May 17.

Neonatal Neuroscience, Translational Health Sciences, University of Bristol, Bristol, United Kingdom.

Background: Binary prediction-models for outcome [death, cognition, presence and severity of cerebral palsy (CP)], using MRI and early clinical data applicable for individual outcome prediction have not been developed.

Methods: From Dec 1 2006 until Dec 31 2013, we recruited 178 infants into a population-based cohort with moderate or severe hypoxic-ischaemic encephalopathy (HIE) including postnatal collapse (PNC,  = 12) and additional diagnoses ( = 12) using CoolCap/TOBY-trial entry-criteria including depressed amplitude-integrated EEG (aEEG). Early clinical/biochemical variables and MRI scans (median day 8) were obtained in 168 infants. Injury severity was scored for cortex, basal ganglia/thalami (BGT), white matter (WM) and posterior limb of the internal capsule, summating to a total injury score (TIS, range 0-11). Outcome was categorized as adverse or favourable at 18-24 months from Bayley-III domains (cut-off 85) and neurological examination including CP classification.

Findings: HIE and entry-aEEG severity were stable throughout the study. Outcome was favourable in 133/178 infants and adverse in 45/178: 17 died, 28 had low Cognition/Language scores, (including 9 with severe CP and 6 mild); seven had mild CP with favourable cognitive outcome. WMxBGT product scores and TIS were strong outcome predictors, and prediction improved when clinical/biochemical variables were added in binary logistic regression. The Positive Predictive Value for adverse outcome was 88%, increasing to 95% after excluding infants with PNC and additional diagnoses. Using WMxBGT in the regression predicted 8 of the 9 children with severe CP.

Interpretation: Binary logistic regression with WMxBGT or TIS and clinical variables gave excellent outcome prediction being 12% better than single variable cross-tabulation. Our MRI scoring and regression models are readily accessible and deserve investigation in other cohorts for group and individual prediction.

Funding: We thank the National Health Service (NHS) and our Universities and funders in UK and Norway: SPARKS, The Moulton Foundation, The Norwegian Research Council, The Lærdal Foundation for Acute Medicine and charitable donations for their support for cooling therapy.
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http://dx.doi.org/10.1016/j.eclinm.2021.100885DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8257962PMC
June 2021

An Age-Specific Atlas for Delineation of White Matter Pathways in Children Aged 6-8 Years.

Brain Connect 2021 Aug 23. Epub 2021 Aug 23.

Clinical Research and Imaging Centre, University of Bristol, Bristol, United Kingdom.

Diffusion magnetic resonance imaging (MRI) allows noninvasive assessment of white matter connectivity in typical development and of changes due to brain injury or pathology. Probabilistic white matter atlases allow diffusion metrics to be measured in specific white matter pathways, and are a critical component in spatial normalization for group analysis. However, given the known developmental changes in white matter it may be suboptimal to use an adult template when assessing data acquired from children. By averaging subject-specific fiber bundles from 28 children aged from 6 to 8 years, we created an age-specific probabilistic white matter atlas for 12 major white matter tracts. Using both the newly developed and Johns Hopkins adult atlases, we compared the atlas with subject-specific fiber bundles in two independent validation cohorts, assessing accuracy in terms of volumetric overlap and measured diffusion metrics. Our age-specific atlas gave better overall performance than the adult atlas, achieving higher volumetric overlap with subject-specific fiber tracking and higher correlation of fractional anisotropy (FA) measurements with those measured from subject-specific fiber bundles. Specifically, estimates of FA values for corticospinal tract, uncinate fasciculus, forceps minor, cingulate gyrus part of the cingulum, and anterior thalamic radiation were all significantly more accurate when estimated with an age-specific atlas. The age-specific atlas allows delineation of white matter tracts in children aged 6-8 years, without the need for tractography, more accurately than when normalizing to an adult atlas. To our knowledge, this is the first publicly available probabilistic atlas of white matter tracts for this age group.
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http://dx.doi.org/10.1089/brain.2021.0058DOI Listing
August 2021

Unanswered questions regarding therapeutic hypothermia for neonates with neonatal encephalopathy.

Semin Fetal Neonatal Med 2021 Jun 12:101257. Epub 2021 Jun 12.

Department of Pediatrics, Division of Neonatal-Perinatal Medicine, University of Texas Southwestern Medical School, Dallas, TX, USA. Electronic address:

Therapeutic hypothermia (TH) is now well established to improve intact survival after neonatal encephalopathy (NE). However, many questions could not be addressed by the randomized controlled trials. Should late preterm newborns with NE be cooled? Is cooling beneficial for mild NE? Is the current therapeutic time window optimal, or could it be shortened or prolonged? Will either milder or deeper hypothermia be effective? Does infection/inflammation exposure in the perinatal period in combination with NE offer potentially beneficial preconditioning or might it obviate hypothermic neuroprotection? In the present review, we dissect the evidence, for whom, when and how can TH best be delivered, and highlight areas that need further research.
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http://dx.doi.org/10.1016/j.siny.2021.101257DOI Listing
June 2021

Disrupted brain connectivity in children treated with therapeutic hypothermia for neonatal encephalopathy.

Neuroimage Clin 2021 10;30:102582. Epub 2021 Feb 10.

Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom; Neonatal Intensive Care Unit, St Michael's Hospital, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom. Electronic address:

Therapeutic hypothermia following neonatal encephalopathy due to birth asphyxia reduces death and cerebral palsy. However, school-age children without cerebral palsy treated with therapeutic hypothermia for neonatal encephalopathy still have reduced performance on cognitive and motor tests, attention difficulties, slower reaction times and reduced visuo-spatial processing abilities compared to typically developing controls. We acquired diffusion-weighted imaging data from school-age children without cerebral palsy treated with therapeutic hypothermia for neonatal encephalopathy at birth, and a matched control group. Voxelwise analysis (33 cases, 36 controls) confirmed reduced fractional anisotropy in widespread areas of white matter in cases, particularly in the fornix, corpus callosum, anterior and posterior limbs of the internal capsule bilaterally and cingulum bilaterally. In structural brain networks constructed using probabilistic tractography (22 cases, 32 controls), graph-theoretic measures of strength, local and global efficiency, clustering coefficient and characteristic path length were found to correlate with IQ in cases but not controls. Network-based statistic analysis implicated brain regions involved in visuo-spatial processing and attention, aligning with previous behavioural findings. These included the precuneus, thalamus, left superior parietal gyrus and left inferior temporal gyrus. Our findings demonstrate that, despite the manifest successes of therapeutic hypothermia, brain development is impaired in these children.
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http://dx.doi.org/10.1016/j.nicl.2021.102582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7906894PMC
July 2021

The effects of Xenon gas inhalation on neuropathology in a placental-induced brain injury model in neonates: A pilot study.

Acta Paediatr 2021 01 3;110(1):119-122. Epub 2020 Aug 3.

Neonatal Neuroscience, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.

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http://dx.doi.org/10.1111/apa.15486DOI Listing
January 2021

Variability and sex-dependence of hypothermic neuroprotection in a rat model of neonatal hypoxic-ischaemic brain injury: a single laboratory meta-analysis.

Sci Rep 2020 07 2;10(1):10833. Epub 2020 Jul 2.

Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Domus Medica, Sognsvannsveien 9, 0372, Oslo, Norway.

Therapeutic hypothermia (HT) is standard care for term infants with hypoxic-ischaemic (HI) encephalopathy. However, the efficacy of HT in preclinical models, such as the Vannucci model of unilateral HI in the newborn rat, is often greater than that reported from clinical trials. Here, we report a meta-analysis of data from every experiment in a single laboratory, including pilot data, examining the effect of HT in the Vannucci model. Across 21 experiments using 106 litters, median (95% CI) hemispheric area loss was 50.1% (46.0-51.9%; n = 305) in the normothermia group, and 41.3% (35.1-44.9%; n = 317) in the HT group, with a bimodal injury distribution. Median neuroprotection by HT was 17.6% (6.8-28.3%), including in severe injury, but was highly-variable across experiments. Neuroprotection was significant in females (p < 0.001), with a non-significant benefit in males (p = 0.07). Animals representing the median injury in each group within each litter (n = 277, 44.5%) were also analysed using formal neuropathology, which showed neuroprotection by HT throughout the brain, particularly in females. Our results suggest an inherent variability and sex-dependence of the neuroprotective response to HT, with the majority of studies in the Vannucci model vastly underpowered to detect true treatment effects due to the distribution of injury.
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http://dx.doi.org/10.1038/s41598-020-67532-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7331720PMC
July 2020

Closed circuit xenon delivery for 72h in neonatal piglets following hypoxic insult using an ambient pressure automated control system: Development, technical evaluation and pulmonary effects.

PLoS One 2020 21;15(1):e0224447. Epub 2020 Jan 21.

Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, England, United Kingdom.

Background: Therapeutic hypothermia (TH) for 72h is the standard treatment following neonatal encephalopathy (NE). However, one-third do not benefit and adjunctive therapies are urgently needed. Xenon enhances neuroprotection with TH when administered at 50% concentration within 5hours of hypoxia in experimental studies. Delayed initiation (~10 hours of age) of 30% xenon for 24 hours during TH did not improve early adverse biomarkers in a clinical trial of Xenon+TH vs TH. After hypoxia-ischemia, excitotoxic injury via N-methyl-D-aspartate receptor overactivation lasts days. Since xenon partially inhibits this receptor, we hypothesised that giving 50% xenon throughout the entire 72h TH and rewarming periods would enhance neuroprotection. Xenon costs $30/litre, so a closed-circuit breathing system is desirable with automated fresh gas delivery.

Methods: Seven mechanically ventilated newborn pigs were randomized to receive 50% inhaled xenon for 72h during hypothermia (rectal-temperature 35°C) and subsequent rewarming following a global hypoxic-ischemic insult (XeHT, N = 4) or under normothermia for 72h (rectal-temperature 38.5°C) following sham insult (XeNT, N = 3). An automated fresh gas delivery system injected oxygen/air/xenon boluses into a closed-circuit based on measured gas concentrations.

Results And Discussion: Median (IQR) xenon consumption was 0.31 L/h (0.18, 0.50) and 0.34L/h (0.32, 0.49) for hypothermic and normothermic groups respectively, 0.34L/h (0.25, 0.53) overall. 92% of 9626 xenon and 69% of 9635 oxygen measurements were within 20% variation from targets. For xenon concentration, the median absolute performance errors for the XeHT and XeNT groups were 6.14% and 3.84% respectively and 4.31% overall. For oxygen these values were 13.42%, 15.05% and 12.4% respectively. There were no adverse pulmonary pathophysiology findings. Clinical problems over the total period included three related to sensors, seven breathing system leaks, ten partial and one complete tracheal tube occlusion episodes.

Conclusion: The automated controller functioned as intended maintaining an inhaled xenon concentration close to the 50% target for 72-78h at a xenon cost of $11.1/h.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0224447PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974042PMC
March 2020

A CEP104-CSPP1 Complex Is Required for Formation of Primary Cilia Competent in Hedgehog Signaling.

Cell Rep 2019 08;28(7):1907-1922.e6

Department of Radiation Biology, Institute for Cancer Research, OUH-Norwegian Radium Hospital, Oslo, Norway. Electronic address:

CEP104 is an evolutionarily conserved centrosomal and ciliary tip protein. CEP104 loss-of-function mutations are reported in patients with Joubert syndrome, but their function in the etiology of ciliopathies is poorly understood. Here, we show that cep104 silencing in zebrafish causes cilia-related manifestations: shortened cilia in Kupffer's vesicle, heart laterality, and cranial nerve development defects. We show that another Joubert syndrome-associated cilia tip protein, CSPP1, interacts with CEP104 at microtubules for the regulation of axoneme length. We demonstrate in human telomerase reverse transcriptase-immortalized retinal pigmented epithelium (hTERT-RPE1) cells that ciliary translocation of Smoothened in response to Hedgehog pathway stimulation is both CEP104 and CSPP1 dependent. However, CEP104 is not required for the ciliary recruitment of CSPP1, indicating that an intra-ciliary CEP104-CSPP1 complex controls axoneme length and Hedgehog signaling competence. Our in vivo and in vitro analyses of CEP104 define its interaction with CSPP1 as a requirement for the formation of Hedgehog signaling-competent cilia, defects that underlie Joubert syndrome.
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http://dx.doi.org/10.1016/j.celrep.2019.07.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6702141PMC
August 2019

Neonatal encephalopathy and hypoxic-ischemic encephalopathy.

Handb Clin Neurol 2019 ;162:217-237

Department of Physiology University of Oslo, Oslo, Norway; Neonatal Neuroscience, Translational Health Sciences, University of Bristol, Bristol, United Kingdom.

Acute hypoxic-ischemic encephalopathy around the time of birth remains a major cause of death and life-long disability. The key insight that led to the modern revival of studies of neuroprotection was that, after profound asphyxia, many brain cells show initial recovery from the insult during a short "latent" phase, typically lasting approximately 6h, only to die hours to days later after a "secondary" deterioration characterized by seizures, cytotoxic edema, and progressive failure of cerebral oxidative metabolism. Studies designed around this framework showed that mild hypothermia initiated as early as possible before the onset of secondary deterioration and continued for a sufficient duration to allow the secondary deterioration to resolve is associated with potent, long-lasting neuroprotection. There is now compelling evidence from randomized controlled trials that mild to moderate induced hypothermia significantly improves survival and neurodevelopmental outcomes in infancy and mid-childhood.
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http://dx.doi.org/10.1016/B978-0-444-64029-1.00010-2DOI Listing
January 2020

School-age outcomes of children without cerebral palsy cooled for neonatal hypoxic-ischaemic encephalopathy in 2008-2010.

Arch Dis Child Fetal Neonatal Ed 2020 Jan 29;105(1):8-13. Epub 2019 Apr 29.

Faculty of Health Sciences, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.

Objective: Since therapeutic hypothermia became standard care for neonatal hypoxic-ischaemic encephalopathy (HIE), even fewer infants die or have disability at 18-month assessment than in the clinical trials. However, longer term follow-up of apparently unimpaired children is lacking. We investigated the cognitive, motor and behavioural performances of survivors without cerebral palsy (CP) cooled for HIE, in comparison with matched non-HIE control children at 6-8 years.

Design: Case-control study.

Participants: 29 case children without CP, cooled in 2008-2010 and 20 age-matched, sex-matched and social class-matched term-born controls.

Measures: Wechsler Intelligence Scales for Children, Fourth UK Edition, Movement Assessment Battery for Children, Second Edition (MABC-2) and Strengths and Difficulties Questionnaire.

Results: Cases compared with controls had significantly lower mean (SD) full-scale IQ (91 [10.37]vs105[13.41]; mean difference (MD): -13.62, 95% CI -20.53 to -6.71) and total MABC-2 scores (7.9 [3.26]vs10.2[2.86]; MD: -2.12, 95% CI -3.93 to -0.3). Mean differences were significant between cases and controls for verbal comprehension (-8.8, 95% CI -14.25 to -3.34), perceptual reasoning (-13.9, 95% CI-20.78 to -7.09), working memory (-8.2, 95% CI-16.29 to -0.17), processing speed (-11.6, 95% CI-20.69 to -2.47), aiming and catching (-1.6, 95% CI-3.26 to -0.10) and manual dexterity (-2.8, 95% CI-4.64 to -0.85). The case group reported significantly higher median (IQR) total (12 [6.5-13.5] vs 6 [2.25-10], p=0.005) and emotional behavioural difficulties (2 [1-4.5] vs 0.5 [0-2.75], p=0.03) and more case children needed extra support in school (34%vs5%, p=0.02) than the control group.

Conclusions: School-age children without CP cooled for HIE still have reduced cognitive and motor performance and more emotional difficulties than their peers, strongly supporting the need for school-age assessments.
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http://dx.doi.org/10.1136/archdischild-2018-316509DOI Listing
January 2020

Attention and visuo-spatial function in children without cerebral palsy who were cooled for neonatal encephalopathy: a case-control study.

Brain Inj 2019 29;33(7):894-898. Epub 2019 Mar 29.

d Translational Health Sciences, Bristol Medical School, St Michael's Hospital , University of Bristol , UK.

: Dorsal-stream functions are vulnerable to early brain injury associated with neonatal encephalopathy (NE) following perinatal asphyxia, even in children not developing cerebral palsy (CP). Since therapeutic hypothermia (TH) became the standard treatment for NE, the incidence of CP is reduced but the impact on dorsal-stream functions is unknown. We aimed to compare dorsal-stream functions in TH-treated survivors of NE, without CP, with those of matched controls. : We administered tests of dorsal-stream function to 29 case children aged 6-to-8 years treated with TH for NE and without CP, and 20 age, sex and social class matched controls. We used the Conner's Continuous Performance Test (CPT) 2 Edition to assess attentiveness, based upon Hit Reaction Time (HRT) percentile score and HRT standard error percentile, the CPT HRT block change measure to assess sustained attention and the NEPSY-II block construction and arrows tests to assess visuo-spatial performance and mental rotation. : Case children performed significantly worse than controls on measures of attention and visuo-spatial function. : Children given TH treatment for NE can have subtle attention difficulties with slower reaction times and reduced visuo-spatial processing. These findings illustrate the continued vulnerability of dorsal-stream functions following NE despite the use of TH.
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http://dx.doi.org/10.1080/02699052.2019.1597163DOI Listing
April 2020

Should therapeutic hypothermia be offered to babies with mild neonatal encephalopathy in the first 6 h after birth?

Pediatr Res 2019 03 16;85(4):442-448. Epub 2019 Jan 16.

Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.

Infants with moderate to severe neonatal encephalopathy (NE) benefit significantly from therapeutic hypothermia, with reduced risk of death or disability. However, the need for therapeutic hypothermia for infants with milder NE remains unclear. It has been suggested that these infants should not be offered therapeutic hypothermia as they may not be at risk for adverse neurodevelopmental outcome and that the balance of risk against potential benefit is unknown. Several key questions need to be answered including first, whether one can define NE in the first 6 h after birth so as to accurately distinguish infants with brain injury who may be at risk for adverse neurodevelopmental consequences. Second, will treatment of infants with mild NE with therapeutic hypothermia improve or even worsen neurological outcomes? Although alternate treatment protocols for mild NE may be feasible, the use of the current approach combined with rigorous avoidance of hyperthermia and initiation of hypothermia as early as possible after birth may promote optimal outcomes. Animal experimental data support the potential for greater benefit for mild HIE compared with moderate to severe HIE. This review will summarize current knowledge of mild NE and the challenges to a trial in this population.
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http://dx.doi.org/10.1038/s41390-019-0291-1DOI Listing
March 2019

Therapeutic Hypothermia in Neonatal Hypoxic-Ischemic Encephalopathy.

Curr Neurol Neurosci Rep 2019 01 14;19(2). Epub 2019 Jan 14.

Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand.

Purpose Of Review: Therapeutic hypothermia reduces death or disability in term and near-term infants with moderate-severe hypoxic-ischemic encephalopathy. Nevertheless, many infants still survive with disability, despite hypothermia, supporting further research in to ways to further improve neurologic outcomes.

Recent Findings: Recent clinical and experimental studies have refined our understanding of the key parameters for hypothermic neuroprotection, including timing of initiation, depth, and duration of hypothermia, and subsequent rewarming rate. However, important knowledge gaps remain. There is encouraging clinical evidence from a small phase II trial that combined treatment of hypothermia with recombinant erythropoietin further reduces risk of disability but definitive studies are still needed. In conclusion, recent studies suggest that current protocols for therapeutic hypothermia are near-optimal, and that the key to better neurodevelopmental outcomes is earlier diagnosis and initiation of hypothermia after birth. Further research is essential to find and evaluate ways to further improve outcomes after hypoxic-ischemic encephalopathy, including add-on therapies for therapeutic hypothermia and preventing pyrexia during labor and delivery.
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http://dx.doi.org/10.1007/s11910-019-0916-0DOI Listing
January 2019

Start cooling as soon as possible.

Acta Paediatr 2019 04 21;108(4):771. Epub 2019 Jan 21.

Neonatal Neuroscience, School of Clinical Sciences, University of Bristol, Bristol, UK.

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http://dx.doi.org/10.1111/apa.14710DOI Listing
April 2019

Major concerns about late hypothermia study.

Acta Paediatr 2019 04 28;108(4):588-589. Epub 2018 Nov 28.

Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

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http://dx.doi.org/10.1111/apa.14640DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6587492PMC
April 2019

Hypothermia Is Neuroprotective after Severe Hypoxic-Ischaemic Brain Injury in Neonatal Rats Pre-Exposed to PAM3CSK4.

Dev Neurosci 2018 1;40(3):189-197. Epub 2018 Jun 1.

Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

Background: Preclinical research on the neuroprotective effect of hypothermia (HT) after perinatal asphyxia has shown variable results, depending on comorbidities and insult severity. Exposure to inflammation increases vulnerability of the neonatal brain to hypoxic-ischaemic (HI) injury, and could be one explanation for those neonates whose injury is unexpectedly severe. Gram-negative type inflammatory exposure by lipopolysaccharide administration prior to a mild HI insult results in moderate brain injury, and hypothermic neuroprotection is negated. However, the neuroprotective effect of HT is fully maintained after gram-positive type inflammatory exposure by PAM3CSK4 (PAM) pre-administration in the same HI model. Whether HT is neuroprotective in severe brain injury with gram-positive inflammatory pre-exposure has not been investigated.

Methods: 59 seven-day-old rat pups were subjected to a unilateral HI insult, with left carotid artery ligation followed by 90-min hypoxia (8% O2 at Trectal 36°C). An additional 196 pups received intraperitoneal 0.9% saline (control) or PAM1 mg/kg, 8 h before undergoing the same HI insult. After randomisation to 5 h normothermia (NT37°C) or HT32°C, pups survived 1 week before they were sacrificed by perfusion fixation. Brains were harvested for hemispheric and hippocampal area loss analyses at postnatal day 14, as well as immunostaining for neuron count in the HIP CA1 region.

Results: Normothermic PAM animals (PAM-NT) had a comparable median area loss (hemispheric: 60% [95% CI 33-66]; hippocampal: 61% [95% CI 29-67]) to vehicle animals (Veh-NT) (hemispheric: 58% [95% CI 11-64]; hippocampal: 60% [95% CI 19-68]), which is defined as severe brain injury. Furthermore, mortality was low and similar in the two groups (Veh-NT 4.5% vs. PAM-NT 6.6%). HT reduced hemispheric and hippocampal injury in the Veh group by 13 and 28%, respectively (hemispheric: p = 0.048; hippocampal: p = 0.042). HT also provided neuroprotection in the PAM group, reducing hemispheric injury by 22% (p = 0.03) and hippocampal injury by 37% (p = 0.027).

Conclusion: In these experiments with severe brain injury, Toll-like receptor-2 triggering prior to HI injury does not have an additive injurious effect, and there is a small but significant neuroprotective effect of HT. HT appears to be neuroprotective over a continuum of injury severity in this model, and the effect size tapers off with increasing area loss. Our results indicate that gram-positive inflammatory exposure prior to HI injury does not negate the neuroprotective effect of HT in severe brain injury.
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http://dx.doi.org/10.1159/000487798DOI Listing
January 2019

Fentanyl Induces Cerebellar Internal Granular Cell Layer Apoptosis in Healthy Newborn Pigs.

Front Neurol 2018 1;9:294. Epub 2018 May 1.

Neonatal Neuroscience, School of Clinical Sciences, University of Bristol, St. Michael's Hospital, Bristol, United Kingdom.

Background: Opioids like fentanyl are regularly used in neonates for analgesia and sedation. So far, they have been reported to be safe and eligible to use. The cerebellum has become a focus of neurodevelopmental research within the last years, as it is known to play an important role in long-lasting motor, cognitive, and other behavioral changes. The cerebellar cortex is of major importance in the coordinative role of the cerebellum and highly vulnerable to injury and impaired growth.

Objective: This study was performed to evaluate the apoptotic effect of intravenous fentanyl infusion on the cerebellum in healthy newborn pigs.

Methods: Thirteen healthy pigs (
Results: We found that there was an increase in cells with apoptotic morphology in the internal granular cell layer in the NTFe group. For quantification, we found a significant increase in cell death in group (1) [median (range) number of caspase-3-positive cell group (1) 8 (1-22) vs. group (2) 1 (1-6) and TUNEL-positive cells (1) 6 (1-10) vs. (2) 1 (0-4)]. In both groups, there was no difference in the number of Purkinje cells. Both groups had comparable and stable physiological parameters throughout the 24 h period.

Conclusion: Twenty-four hours of continuous intravenous fentanyl infusion increased apoptosis in the internal granular cell layer in the cerebellum of healthy newborn pigs.
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http://dx.doi.org/10.3389/fneur.2018.00294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5938373PMC
May 2018

Combining two good treatments makes it worse.

Brain Behav Immun 2018 07 17;71:7-8. Epub 2018 Apr 17.

Neonatal Neuroscince, University of Bristol, Bristol, United Kingdom; Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway. Electronic address:

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http://dx.doi.org/10.1016/j.bbi.2018.04.008DOI Listing
July 2018

Neonatal Systemic Inflammation Induces Inflammatory Reactions and Brain Apoptosis in a Pathogen-Specific Manner.

Neonatology 2018 23;113(3):212-220. Epub 2017 Dec 23.

Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

Background: After neonatal asphyxia, therapeutic hypothermia (HT) is the only proven treatment option. Although established as a neuroprotective therapy, benefit from HT has been questioned when infection is a comorbidity to hypoxic-ischaemic (HI) brain injury. Gram-negative and gram-positive species activate the immune system through different pathogen recognition receptors and subsequent immunological systems. In rodent models, gram-negative (lipopolysaccharide [LPS]) and gram-positive (PAM3CSK4 [PAM]) inflammation similarly increase neuronal vulnerability to HI. Interestingly, while LPS pre-sensitisation negates the neuroprotective effect of HT, HT is highly beneficial after PAM-sensitised HI brain injury.

Objective: We aimed to examine whether systemic gram-positive or gram-negative inflammatory sensitisation affects juvenile rat pups per se, without an HI insult.

Methods: Neonatal 7-day-old rats (n = 215) received intraperitoneal injections of vehicle (0.9% NaCl), LPS (0.1 mg/kg), or PAM (1 mg/kg). Core temperature and weight gain were monitored. Brain cytokine expression (IL-6, IL-1β, TNF-α, and IL-10, via PCR), apoptosis (cleaved caspase 3, via Western blots), and microglial activation (Iba1, via immunohistochemistry) were examined.

Results: LPS induced an immediate drop in core temperature followed by poor weight gain, none of which were seen after PAM. Furthermore, LPS induced brain apoptosis, while PAM did not. The magnitude and temporal profile of brain cytokine expression differed between LPS- and PAM-injected animals.

Conclusion: These findings reveal sepsis-like conditions and neuroinflammation specific to the inflammatory stimulus (gram-positive vs. gram-negative) in the neonatal rat. They emphasise the importance of pre-clinical models being pathogen dependent, and should always be carefully tailored to their clinical scenario.
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http://dx.doi.org/10.1159/000481980DOI Listing
September 2019

Reduced infancy and childhood epilepsy following hypothermia-treated neonatal encephalopathy.

Epilepsia 2017 11 29;58(11):1902-1911. Epub 2017 Sep 29.

Neonatal Neuroscience, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom.

Objective: To investigate what proportion of a regional cohort of cooled infants with neonatal encephalopathy develop epilepsy (determined by the International League Against Epilepsy [ILAE] definition and the number of antiepileptic drugs [AEDs]) up to 8 years of age.

Methods: From 2006-2013, 151 infants with perinatal asphyxia underwent 72 h cooling. Clinical and amplitude-integrated electroencepalography (aEEG) with single-channel EEG-verified neonatal seizures were treated with AEDs. Brain magnetic resonance imaging (MRI) was assessed using a 0-11 severity score. Postneonatal seizures, epilepsy rates, and AED treatments were documented. One hundred thirty-four survivors were assessed at 18-24 months; adverse outcome was defined as death or Bayley III composite Cognition/Language or Motor scores <85 and/or severe cerebral palsy or severely reduced vision/hearing. Epilepsy rates in 103 children age 4-8 years were also documented.

Results: aEEG confirmed seizures occurred precooling in 77 (57%) 151 of neonates; 48% had seizures during and/or after cooling and received AEDs. Only one infant was discharged on AEDs. At 18-24 months, one third of infants had an adverse outcome including 11% mortality. At 2 years, 8 (6%) infants had an epilepsy diagnosis (ILAE definition), of whom 3 (2%) received AEDs. Of the 103 4- to 8-year-olds, 14 (13%) had developed epilepsy, with 7 (7%) receiving AEDs. Infants/children on AEDs had higher MRI scores than those not on AEDs (median [interquartile range] 9 [8-11] vs. 2 [0-4]) and poorer outcomes. Nine (64%) of 14 children with epilepsy had cerebral palsy compared to 13 (11%) of 120 without epilepsy, and 10 (71%) of 14 children with epilepsy had adverse outcomes versus 23 (19%) of 120 survivors without epilepsy. The number of different AEDs given to control neonatal seizures, aEEG severity precooling, and MRI scores predicted childhood epilepsy.

Significance: We report, in a regional cohort of infants cooled for perinatal asphyxia, 6% with epilepsy at 2 years (2% on AEDs) increasing to 13% (7% on AEDs) at early school age. These AED rates are much lower than those reported in the cooling trials, even with adjusting for our cohort's milder asphyxia. Long-term follow-up is needed to document final epilepsy rates.
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http://dx.doi.org/10.1111/epi.13914DOI Listing
November 2017

Amplitude-Integrated Electroencephalography Improves the Identification of Infants with Encephalopathy for Therapeutic Hypothermia and Predicts Neurodevelopmental Outcomes at 2 Years of Age.

J Pediatr 2017 08 23;187:34-42. Epub 2017 May 23.

Neonatal Neuroscience, School of Medical Sciences, University of Bristol, Bristol, United Kingdom; Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway. Electronic address:

Objectives: To examine whether using an amplitude-integrated electroencephalography (aEEG) severity pattern as an entry criterion for therapeutic hypothermia better selects infants with hypoxic-ischemic encephalopathy and to assess the time-to-normal trace for aEEG and magnetic resonance imaging (MRI) lesion load as 24-month outcome predictors.

Study Design: Forty-seven infants meeting Norwegian therapeutic hypothermia guidelines were enrolled prospectively. Eight-channel EEG/aEEG was recorded from 6 hours until after rewarming, and read after discharge. Neonatal MRI brain scans were scored for summated (range 0-11) regional lesion load. A poor outcome at 2 years was defined as death or a Bayley Scales of Infant-Toddler Development cognitive or motor composite score of <85 or severe hearing or visual loss.

Results: Three severity groups were defined from the initial aEEG; continuous normal voltage (CNV; n = 15), discontinuous normal voltage (DNV; n = 18), and a severe aEEG voltage pattern (SEVP; n = 14). Any seizure occurrence was 7% CNV, 50% DNV, and 100% SEVP. Infants with SEVP with poor vs good outcome had a significantly longer median (IQR) time-to-normal trace: 58 hours (9-79) vs 18 hours (12-19) and higher MRI lesion load: 10 (3-10) vs 2 (1-5). A poor outcome was noted in 3 of 15 infants with CNV, 4 of 18 infants with DNV, and 8 of 14 infants with SEVP. Using multiple stepwise linear regression analyses including only infants with abnormal aEEG (DNV and SEVP), MRI lesion load significantly predicted cognitive and motor scores. For the SEVP group alone, time-to-normal trace was a stronger outcome predictor than MRI score. No variable predicted outcome in infants with CNV.

Conclusions: Selection of infants with encephalopathy for therapeutic hypothermia after perinatal asphyxia may be improved by including only infants with an early moderate or severely depressed background aEEG trace.
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http://dx.doi.org/10.1016/j.jpeds.2017.04.041DOI Listing
August 2017

Hypothermic Neuronal Rescue from Infection-Sensitised Hypoxic-Ischaemic Brain Injury Is Pathogen Dependent.

Dev Neurosci 2017 14;39(1-4):238-247. Epub 2017 Apr 14.

Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

Perinatal infection increases the vulnerability of the neonatal brain to hypoxic-ischaemic (HI) injury. Hypothermia treatment (HT) does not provide neuroprotection after pre-insult inflammatory sensitisation by lipopolysaccharide (LPS), a gram-negative bacterial wall constituent. However, early-onset sepsis in term babies is caused by gram-positive species in more than 90% of cases, and neuro-inflammatory responses triggered through the gram-negative route (Toll-like receptor 4, TLR-4) are different from those induced through the gram-positive route via TLR-2. Whether gram-positive septicaemia sensitises the neonatal brain to hypoxia and inhibits the neuroprotective effect of HT is unknown. Seven-day-old Wistar rats (n = 178) were subjected to intraperitoneal injections of PAM3CSK4 (1 mg/kg, a synthetic TLR-2 agonist) or vehicle (0.9% NaCl). After an 8-h delay, the left carotid artery was ligated followed by 50 min of hypoxia (8% O2) at a rectal temperature of 36°C. Pups received a 5-h treatment of normothermia (NT, 37°C) or HT (32°C) immediately after the insult. Brains were harvested after 7 days' survival for hemispheric and hippocampal area loss analyses and immunolabelling of microglia (Iba1) and hippocampal neurons (NeuN). Normothermic PAM3CSK4-injected animals showed significantly more brain injury than vehicle animals (p = 0.014). Compared to NT, HT significantly reduced injury in the PAM3CSK4-injected animals, with reduced area loss (p < 0.001), reduced microglial activation (p = 0.006), and increased neuronal rescue in the CA1 region (p < 0.001). Experimental induction of a sepsis-like condition through the gram-positive pathway sensitises the brain to HI injury. HT was highly neuroprotective after the PAM3CSK4-triggered injury, suggesting HT may be neuroprotective in the presence of a gram-positive infection. These results are in strong contrast to LPS studies where HT is not neuroprotective.
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http://dx.doi.org/10.1159/000455838DOI Listing
February 2018

Rectal temperature in the first five hours after hypoxia-ischemia critically affects neuropathological outcomes in neonatal rats.

Pediatr Res 2018 02 1;83(2):536-544. Epub 2017 Nov 1.

Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

BackgroundHyperthermia after hypoxia-ischemia (HI) in newborn infants is associated with worse neurological outcomes. Loss of thermoregulation may also be associated with greater injury.MethodsIn the postnatal-day 7 (P7) rat, the effect of 5 h of graded hyperthermia (38 °C or 39 °C) immediately after unilateral HI was compared with normothermia (NT, 37 °C) and therapeutic hypothermia (TH, 32 °C). Early (negative geotaxis) and late (staircase test) behavioral testing was performed, as well as neuropathology scoring in adulthood. Separately, P7 rats were exposed to HI, and individual nesting temperatures were monitored before analysis of neuropathology at P14.ResultsMortality increased as temperature was increased from 38 °C (0%) to 39 °C (50%) after HI. Hyperthermia also resulted in early behavioral deficits compared with NT. In adulthood, pathology scores in the thalamus, basal ganglia, cortex, and hippocampus increased as post-hypoxic temperature increased above NT. Significant global neuroprotection was seen in the TH group. However, no significant difference was seen between HI groups in the staircase test. One hour after HI, the core temperature of pups was inversely correlated with global pathology scores at P14.ConclusionEarly temperature is a significant determinant of injury after experimental HI. Spontaneous decreases in core temperature after HI may confound neuroprotection studies.
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http://dx.doi.org/10.1038/pr.2017.51DOI Listing
February 2018

Therapeutic hypothermia translates from ancient history in to practice.

Pediatr Res 2017 01 27;81(1-2):202-209. Epub 2016 Sep 27.

Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.

Acute postasphyxial encephalopathy around the time of birth remains a major cause of death and disability. The possibility that hypothermia may be able to prevent or lessen asphyxial brain injury is a "dream revisited". In this review, a historical perspective is provided from the first reported use of therapeutic hypothermia for brain injuries in antiquity, to the present day. The first uncontrolled trials of cooling for resuscitation were reported more than 50 y ago. The seminal insight that led to the modern revival of studies of neuroprotection was that after profound asphyxia, many brain cells show initial recovery from the insult during a short "latent" phase, typically lasting ~6 h, only to die hours to days later during a "secondary" deterioration phase characterized by seizures, cytotoxic edema, and progressive failure of cerebral oxidative metabolism. Studies designed around this conceptual framework showed that mild hypothermia initiated as early as possible before the onset of secondary deterioration, and continued for a sufficient duration to allow the secondary deterioration to resolve, is associated with potent, long-lasting neuroprotection. There is now compelling evidence from randomized controlled trials that mild induced hypothermia significantly improves intact survival and neurodevelopmental outcomes to midchildhood.
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http://dx.doi.org/10.1038/pr.2016.198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5233584PMC
January 2017

Central Nervous System Injury and Temperature Management.

Ther Hypothermia Temp Manag 2016 Aug 22;6(3):112-5. Epub 2016 Jul 22.

4 Department of Physiology, Institute of Basic Medical Sciences, University of Oslo , Oslo, Norway .

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http://dx.doi.org/10.1089/ther.2016.29014.pjkDOI Listing
August 2016

Heart rate response to therapeutic hypothermia in infants with hypoxic-ischaemic encephalopathy.

Resuscitation 2016 09 28;106:53-7. Epub 2016 Jun 28.

Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Norway; School of Clinical Sciences, University of Bristol, UK.

Aim Of The Study: Neonatal encephalopathy (NE) of hypoxic-ischaemic origin may cause death or life-long disability which is reduced by therapeutic hypothermia (TH). Our objective was to assess HR response in infants undergoing TH after perinatal asphyxia.

Methods: We performed a retrospective case series, from a single-centre tertiary care NICU. We included ninety-two infants with NE of likely hypoxic-ischaemic origin, moderate or severe, treated with TH (n=60) or normothermia (n=32) who had 18 month outcome data and at least 12 HR recordings the first 24h after birth (1998-2010) Bristol, UK. Poor outcome was defined as death or severe disability. Data are reported as medians and 95% confidence intervals (CI).

Results: TH to 33.5°C decreased HR by 30bpm to 92bpm (95% CI: 88, 96) 12h after birth in infants with NE and good outcome as compared to infants treated at normothermia 118bpm (95% CI: 110, 130). Despite constant low rectal temperature, HR increased gradually during cooling from 36 to 72h to 97bpm (89, 106) approaching the normothermia group, 117bpm (96, 133). During TH, infants with poor outcome had higher HR at 12h after birth (112bpm, 95% CI: 92, 115) as compared to infants with good outcome (p=0.004). Inotropic support increased HR by 17bpm in infants with good outcome and by 22bpm in infants with poor outcome.

Conclusions: In NE, TH decreases HR the first day of life. HR remained lower during TH, but increased during the last day of TH. Infants with poor outcome have higher HR.
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http://dx.doi.org/10.1016/j.resuscitation.2016.06.023DOI Listing
September 2016

Xenon Combined with Therapeutic Hypothermia Is Not Neuroprotective after Severe Hypoxia-Ischemia in Neonatal Rats.

PLoS One 2016 2;11(6):e0156759. Epub 2016 Jun 2.

Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.

Background: Therapeutic hypothermia (TH) is standard treatment following perinatal asphyxia in newborn infants. Experimentally, TH is neuroprotective after moderate hypoxia-ischemia (HI) in seven-day-old (P7) rats. However, TH is not neuroprotective after severe HI. After a moderate HI insult in newborn brain injury models, the anesthetic gas xenon (Xe) doubles TH neuroprotection. The aim of this study was to examine whether combining Xe and TH is neuroprotective as applied in a P7 rat model of severe HI.

Design/methods: 120 P7 rat pups underwent a severe HI insult; unilateral carotid artery ligation followed by hypoxia (8% O2 for 150min at experimental normothermia (NT-37: Trectal 37°C). Surviving pups were randomised to immediate NT-37 for 5h (n = 36), immediate TH-32: Trectal 32°C for 5h (n = 25) or immediate TH-32 plus 50% inhaled Xe for 5h (n = 24). Pups were sacrificed after one week of survival. Relative area loss of the ligated hemisphere was measured, and neurons in the subventricular zone of this injured hemisphere were counted, to quantify brain damage.

Results: Following the HI insult, median (interquartile range, IQR) hemispheric brain area loss was similar in all groups: 63.5% (55.5-75.0) for NT-37 group, 65.0% (57.0-65.0) for TH-32 group, and 66.5% (59.0-72.0) for TH-32+Xe50% group (not significant). Correspondingly, there was no difference in neuronal cell count (NeuN marker) in the subventricular zone across the three treatment groups.

Conclusions: Immediate therapeutic hypothermia with or without additional 50% inhaled Xe, does not provide neuroprotection one week after severe HI brain injury in the P7 neonatal rat. This model aims to mimic the clinical situation in severely asphyxiated neonates and treatment these newborns remains an ongoing challenge.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0156759PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890818PMC
July 2017

Monitoring of cerebral blood flow during hypoxia-ischemia and resuscitation in the neonatal rat using laser speckle imaging.

Physiol Rep 2016 Apr 13;4(7). Epub 2016 Apr 13.

Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway Neonatal Neuroscience, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom

Neonatal hypoxic-ischemic encephalopathy (HIE) is associated with alterations in cerebral blood flow (CBF) as a result of perinatal asphyxia. The extent to whichCBFchanges contribute to injury, and whether treatments that ameliorate these changes might be neuroprotective, is still unknown. Higher throughput techniques to monitorCBFchanges in rodent models ofHIEcan help elucidate the underlying pathophysiology. We developed a laser speckle imaging (LSI) technique to continuously monitorCBFin six postnatal-day 10 (P10) rats simultaneously before, during, and after unilateral hypoxia-ischemia (HI, ligation of the left carotid artery followed by hypoxia in 8% oxygen). After ligation,CBFto the ligated side fell by 30% compared to the unligated side (P < 0.0001). Hypoxia induced a bilateral 55% reduction inCBF, which was partially restored by resuscitation. Compared to resuscitation in air, resuscitation in 100% oxygen increasedCBFto the ligated side by 45% (P = 0.033). Individual variability inCBFresponse to hypoxia between animals accounted for up to 24% of the variability in hemispheric area loss to the ligated side. In both P10 and P7 models of unilateralHI, resuscitation in 100% oxygen did not affect hemispheric area loss, or hippocampalCA1 pyramidal neuron counts, after 1-week survival. ContinuousCBFmonitoring usingLSIin multiple rodents simultaneously can screen potential treatment modalities that affectCBF, and provide insight into the pathophysiology ofHI.
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http://dx.doi.org/10.14814/phy2.12749DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831323PMC
April 2016
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