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McDouall A, Wassink G, Ranasinghe S, Zhou KQ, Karunasinghe RN, Dean JM, Davidson JO. Blockade of connexin hemichannels with tonabersat protects against mild hypoxic ischemic brain injury in neonatal rats. Exp Neurol 2024; 371:114611. [PMID: 37944882 DOI: 10.1016/j.expneurol.2023.114611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 10/15/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND AND PURPOSE There is growing evidence that infants with mild hypoxic-ischemic (HI) encephalopathy have increased risk of brain injury and adverse neurodevelopmental outcomes. Currently, there is no approved treatment for these infants. It was previously shown that blocking connexin 43 hemichannels is neuroprotective in models of moderate to severe HI injury. However, it is yet to be established whether these channels play a role in the evolution of mild HI brain injury, and whether blocking these channels after mild HI is neuroprotective. METHODS HI was induced in postnatal day 10 rats of both sexes by right carotid artery ligation followed by 80 min of hypoxia in 8% oxygen. Pups receiving HI were randomised to receive intraperitoneal injections of either saline, vehicle (2-hydroxypropyl-beta-cyclodextrin polyethylene glycol-400), or tonabersat (2 mg/kg), at 60 min, 24 h, and 48 h after hypoxia. Seven days after HI, brains were harvested for measurement of volume loss and histological analysis. RESULTS HI resulted in a significant reduction in hemispheric, hippocampal, and white matter volumes, which were significantly attenuated after treatment with tonabersat. HI was also associated with a significant reduction in numbers of neurons in the CA1 and CA3 hippocampal regions, a reduction in the numbers of oligodendrocytes in the corpus callosum, and an increase in the number of astrocytes in both regions, which were significantly attenuated by tonabersat treatment. There were no differences in rectal temperatures between tonabersat- and vehicle-treated rat pups. CONCLUSIONS Blockade of connexin hemichannels with tonabersat significantly reduced mild HI injury in the hippocampus and white matter, without causing hypothermia.
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Affiliation(s)
- Alice McDouall
- Department of Physiology, the University of Auckland, New Zealand
| | - Guido Wassink
- Department of Physiology, the University of Auckland, New Zealand
| | | | - Kelly Q Zhou
- Department of Physiology, the University of Auckland, New Zealand
| | | | - Justin M Dean
- Department of Physiology, the University of Auckland, New Zealand
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Cho KHT, Hounsell N, McClendon E, Riddle A, Basappa, Dhillon SK, Bennet L, Back S, Sherman LS, Gunn AJ, Dean JM. Postischemic Infusion of Apigenin Reduces Seizure Burden in Preterm Fetal Sheep. Int J Mol Sci 2023; 24:16926. [PMID: 38069249 PMCID: PMC10706648 DOI: 10.3390/ijms242316926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/23/2023] [Accepted: 11/25/2023] [Indexed: 12/18/2023] Open
Abstract
Seizures are common in preterm newborns and are associated with poor neurodevelopmental outcomes. Current anticonvulsants have poor efficacy, and many have been associated with upregulation of apoptosis in the developing brain. Apigenin, a natural bioactive flavonoid, is a potent inhibitor of hyaluronidase and reduces seizures in adult animal models. However, its impact on perinatal seizures is unclear. In the present study, we examined the effect of apigenin and S3, a synthetic, selective hyaluronidase inhibitor, on seizures after cerebral ischemia in preterm fetal sheep at 0.7 gestation (98-99 days, term ~147 days). Fetuses received sham ischemia (n = 9) or ischemia induced by bilateral carotid occlusion for 25 min. Immediately after ischemia, fetuses received either a continuous infusion of vehicle (0.036% dimethyl sulfoxide, n = 8) or apigenin (50 µM, n = 6). In a pilot study, we also tested infusion of S3 (2 µM, n = 3). Fetuses were monitored continuously for 72 h after ischemia. Infusion of apigenin or S3 were both associated with reduced numbers of animals with seizures, total seizure time, and mean seizure burden. S3 was also associated with a reduction in the total number of seizures over the 72 h recovery period. In animals that developed seizures, apigenin was associated with earlier cessation of seizures. However, apigenin or S3 treatment did not alter recovery of electroencephalographic power or spectral edge frequency. These data support that targeting brain hyaluronidase activity with apigenin or S3 may be an effective strategy to reduce perinatal seizures following ischemia. Further studies are required to determine their effects on neurohistological outcomes.
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Affiliation(s)
- Kenta H. T. Cho
- Department of Physiology, University of Auckland, Auckland 1142, New Zealand; (K.H.T.C.); (N.H.); (S.K.D.); (L.B.); (A.J.G.)
| | - Natalya Hounsell
- Department of Physiology, University of Auckland, Auckland 1142, New Zealand; (K.H.T.C.); (N.H.); (S.K.D.); (L.B.); (A.J.G.)
| | - Evelyn McClendon
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA; (E.M.); (A.R.); (S.B.)
| | - Art Riddle
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA; (E.M.); (A.R.); (S.B.)
| | - Basappa
- Laboratory of Chemical Biology, Department of Studies in Organic Chemistry, University of Mysore, Manasagangotri, Mysore 570006, India;
| | - Simerdeep K. Dhillon
- Department of Physiology, University of Auckland, Auckland 1142, New Zealand; (K.H.T.C.); (N.H.); (S.K.D.); (L.B.); (A.J.G.)
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland 1142, New Zealand; (K.H.T.C.); (N.H.); (S.K.D.); (L.B.); (A.J.G.)
| | - Stephen Back
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA; (E.M.); (A.R.); (S.B.)
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Larry S. Sherman
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA;
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Alistair J. Gunn
- Department of Physiology, University of Auckland, Auckland 1142, New Zealand; (K.H.T.C.); (N.H.); (S.K.D.); (L.B.); (A.J.G.)
| | - Justin M. Dean
- Department of Physiology, University of Auckland, Auckland 1142, New Zealand; (K.H.T.C.); (N.H.); (S.K.D.); (L.B.); (A.J.G.)
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Kelly SB, Dean JM, Zahra VA, Dudink I, Thiel A, Polglase GR, Miller SL, Hooper SB, Bennet L, Gunn AJ, Galinsky R. Progressive inflammation reduces high-frequency EEG activity and cortical dendritic arborisation in late gestation fetal sheep. J Neuroinflammation 2023; 20:124. [PMID: 37226206 DOI: 10.1186/s12974-023-02805-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/15/2023] [Indexed: 05/26/2023] Open
Abstract
BACKGROUND Antenatal infection/inflammation is associated with disturbances in neuronal connectivity, impaired cortical growth and poor neurodevelopmental outcomes. The pathophysiological substrate that underpins these changes is poorly understood. We tested the hypothesis that progressive inflammation in late gestation fetal sheep would alter cortical neuronal microstructure and neural function assessed using electroencephalogram band power analysis. METHODS Fetal sheep (0.85 of gestation) were surgically instrumented for continuous electroencephalogram (EEG) recording and randomly assigned to repeated saline (control; n = 9) or LPS (0 h = 300 ng, 24 h = 600 ng, 48 h = 1200 ng; n = 8) infusions to induce inflammation. Sheep were euthanised 4 days after the first LPS infusion for assessment of inflammatory gene expression, histopathology and neuronal dendritic morphology in the somatosensory cortex. RESULTS LPS infusions increased delta power between 8 and 50 h, with reduced beta power from 18 to 96 h (P < 0.05 vs. control). Basal dendritic length, numbers of dendritic terminals, dendritic arborisation and numbers of dendritic spines were reduced in LPS-exposed fetuses (P < 0.05 vs. control) within the somatosensory cortex. Numbers of microglia and interleukin (IL)-1β immunoreactivity were increased in LPS-exposed fetuses compared with controls (P < 0.05). There were no differences in total numbers of cortical NeuN + neurons or cortical area between the groups. CONCLUSIONS Exposure to antenatal infection/inflammation was associated with impaired dendritic arborisation, spine number and loss of high-frequency EEG activity, despite normal numbers of neurons, that may contribute to disturbed cortical development and connectivity.
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Affiliation(s)
- Sharmony B Kelly
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Justin M Dean
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Valerie A Zahra
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
| | - Ingrid Dudink
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Alison Thiel
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
| | - Graeme R Polglase
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Stuart B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Robert Galinsky
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia.
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia.
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Bailly DK, Reeder RW, Muszynski JA, Meert KL, Ankola AA, Alexander PM, Pollack MM, Moler FW, Berg RA, Carcillo J, Newth C, Berger J, Bell MJ, Dean JM, Nicholson C, Garcia-Filion P, Wessel D, Heidemann S, Doctor A, Harrison R, Dalton H, Zuppa AF. Anticoagulation practices associated with bleeding and thrombosis in pediatric extracorporeal membrane oxygenation; a multi-center secondary analysis. Perfusion 2023; 38:363-372. [PMID: 35220828 DOI: 10.1177/02676591211056562] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To determine associations between anticoagulation practices and bleeding and thrombosis during pediatric extracorporeal membrane oxygenation (ECMO), we performed a secondary analysis of prospectively collected data which included 481 children (<19 years), between January 2012 and September 2014. The primary outcome was bleeding or thrombotic events. Bleeding events included a blood product transfusion >80 ml/kg on any day, pulmonary hemorrhage, or intracranial bleeding, Thrombotic events included pulmonary emboli, intracranial clot, limb ischemia, cardiac clot, and arterial cannula or entire circuit change. Bleeding occurred in 42% of patients. Five percent of subjects thrombosed, of which 89% also bled. Daily bleeding odds were independently associated with day prior activated clotting time (ACT) (OR 1.03, 95% CI= 1.00, 1.05, p=0.047) and fibrinogen levels (OR 0.90, 95% CI 0.84, 0.96, p <0.001). Thrombosis odds decreased with increased day prior heparin dose (OR 0.88, 95% CI 0.81, 0.97, p=0.006). Lower ACT values and increased fibrinogen levels may be considered to decrease the odds of bleeding. Use of this single measure, however, may not be sufficient alone to guide optimal anticoagulation practice during ECMO.
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Affiliation(s)
- David K Bailly
- Department of Pediatrics, Division of Pediatric Critical Care, 14434University of Utah, Salt Lake, UT, USA
| | - Ron W Reeder
- Department of Pediatrics, 14434University of Utah, Salt Lake, UT, USA
| | - Jennifer A Muszynski
- Division of Critical Care, 2650Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, 2650Nationwide Children's Hospital, Columbus, OH, USA.,Center for Clinical and Translational Research, 2650The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Kathleen L Meert
- Department of Pediatrics, 2969Children's Hospital of Michigan, Detroit, MI, USA.,2969Central Michigan University, Mt. Pleasant, MI, USA
| | - Ashish A Ankola
- Department of Anesthesiology, Critical Care, and Pain Medicine, 1862Boston Children's Hospital, Boston, MA, USA.,Department of Cardiology, 1862Boston Children's Hospital, Boston, MA, USA
| | - Peta Ma Alexander
- Department of Pediatrics, 14434Harvard Medical School, Boston, MA, USA
| | - Murray M Pollack
- Department of Pediatrics, 8404Children's National Hospital, Washington, DC, USA
| | - Frank W Moler
- Department of Pediatrics and Communicable Diseases, 1259University of Michigan, Ann Arbor, MI, USA
| | - Robert A Berg
- Department of Anesthesia and Critical Care, 6567Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Joseph Carcillo
- Department of Critical Care Medicine, 6619Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Christopher Newth
- Department of Anesthesiology and Critical Care Medicine, 5150Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - John Berger
- Department of Pediatrics, 8404Children's National Hospital, Washington, DC, USA
| | - Michael J Bell
- Department of Pediatrics, 8404Children's National Hospital, Washington, DC, USA
| | - J M Dean
- Department of Pediatrics, Division of Pediatric Critical Care, 14434University of Utah, Salt Lake, UT, USA
| | - Carol Nicholson
- Trauma and Critical Illness Branch, 35040National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA.,35040National Institutes of Health, Bethesda, MD, USA
| | - Pamela Garcia-Filion
- Department of Biomedical Informatics, 14524Phoenix Children's Hospital, Phoenix, AZ, USA
| | - David Wessel
- Department of Pediatrics, 8404Children's National Hospital, Washington, DC, USA
| | - Sabrina Heidemann
- Department of Pediatrics, 2969Children's Hospital of Michigan, Detroit, MI, USA.,2969Central Michigan University, Mt. Pleasant, MI, USA
| | - Allan Doctor
- Department of Pediatrics and Center for Blood Oxygen Transport and Hemostasis, 12264University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Rick Harrison
- Department of Pediatrics, 21785Mattel Children's Hospital UCLA, Los Angeles, CA, USA
| | - Heidi Dalton
- Department of Pediatrics and Heart and Vascular Institute, 3313Inova Fairfax Hospital, Fall Church, VA, USA
| | - Athena F Zuppa
- Department of Anesthesia and Critical Care, 6567Children's Hospital of Philadelphia, Philadelphia, PA, USA
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5
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Yang P, Davidson JO, Zhou KQ, Wilson R, Wassink G, Prasad JD, Bennet L, Gunn AJ, Dean JM. Therapeutic Hypothermia Attenuates Cortical Interneuron Loss after Cerebral Ischemia in Near-Term Fetal Sheep. Int J Mol Sci 2023; 24:ijms24043706. [PMID: 36835117 PMCID: PMC9962824 DOI: 10.3390/ijms24043706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/26/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
Therapeutic hypothermia significantly improves outcomes after neonatal hypoxic-ischemic (HI) encephalopathy but is only partially protective. There is evidence that cortical inhibitory interneuron circuits are particularly vulnerable to HI and that loss of interneurons may be an important contributor to long-term neurological dysfunction in these infants. In the present study, we examined the hypothesis that the duration of hypothermia has differential effects on interneuron survival after HI. Near-term fetal sheep received sham ischemia or cerebral ischemia for 30 min, followed by cerebral hypothermia from 3 h after ischemia end and continued up to 48 h, 72 h, or 120 h recovery. Sheep were euthanized after 7 days for histology. Hypothermia up to 48 h recovery resulted in moderate neuroprotection of glutamate decarboxylase (GAD)+ and parvalbumin+ interneurons but did not improve survival of calbindin+ cells. Hypothermia up to 72 h recovery was associated with significantly increased survival of all three interneuron phenotypes compared with sham controls. By contrast, while hypothermia up to 120 h recovery did not further improve (or impair) GAD+ or parvalbumin+ neuronal survival compared with hypothermia up to 72 h, it was associated with decreased survival of calbindin+ interneurons. Finally, protection of parvalbumin+ and GAD+ interneurons, but not calbindin+ interneurons, with hypothermia was associated with improved recovery of electroencephalographic (EEG) power and frequency by day 7 after HI. The present study demonstrates differential effects of increasing the duration of hypothermia on interneuron survival after HI in near-term fetal sheep. These findings may contribute to the apparent preclinical and clinical lack of benefit of very prolonged hypothermia.
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Davidson JO, Gunn AJ, Dean JM. Back to the beginning: can we stop brain injury before it starts? J Physiol 2022; 600:3013-3014. [PMID: 35652911 PMCID: PMC9328369 DOI: 10.1113/jp283330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 11/30/2022] Open
Affiliation(s)
- Joanne O Davidson
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand
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Reginald-Opara JN, Svirskis D, Paek S, Tang M, O'Carroll SJ, Dean JM, Chamley LW, Wu Z. The involvement of extracellular vesicles in the transcytosis of nanoliposomes through brain endothelial cells, and the impact of liposomal pH-sensitivity. Mater Today Bio 2022; 13:100212. [PMID: 35198960 PMCID: PMC8841812 DOI: 10.1016/j.mtbio.2022.100212] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 10/29/2022] Open
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Kelly SB, Stojanovska V, Zahra VA, Moxham A, Miller SL, Moss TJM, Hooper SB, Nold MF, Nold-Petry CA, Dean JM, Bennet L, Polglase GR, Gunn AJ, Galinsky R. Interleukin-1 blockade attenuates white matter inflammation and oligodendrocyte loss after progressive systemic lipopolysaccharide exposure in near-term fetal sheep. J Neuroinflammation 2021; 18:189. [PMID: 34465372 PMCID: PMC8408978 DOI: 10.1186/s12974-021-02238-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 08/11/2021] [Indexed: 12/14/2022] Open
Abstract
Background Increased systemic and tissue levels of interleukin (IL)-1β are associated with greater risk of impaired neurodevelopment after birth. In this study, we tested the hypothesis that systemic IL-1 receptor antagonist (Ra) administration would attenuate brain inflammation and injury in near-term fetal sheep exposed to lipopolysaccharide (LPS). Methods Chronically instrumented near-term fetal sheep at 0.85 of gestation were randomly assigned to saline infusion (control, n = 9), repeated LPS infusions (0 h = 300 ng, 24 h = 600 ng, 48 h = 1200 ng, n = 8) or repeated LPS plus IL-1Ra infusions (13 mg/kg infused over 4 h) started 1 h after each LPS infusion (n = 9). Sheep were euthanized 4 days after starting infusions for histology. Results LPS infusions increased circulating cytokines and were associated with electroencephalogram (EEG) suppression with transiently reduced mean arterial blood pressure, and increased carotid artery perfusion and fetal heart rate (P < 0.05 vs. control for all). In the periventricular and intragyral white matter, LPS-exposure increased IL-1β immunoreactivity, numbers of caspase 3+ cells and microglia, reduced astrocyte and olig-2+ oligodendrocyte survival but did not change numbers of mature CC1+ oligodendrocytes, myelin expression or numbers of neurons in the cortex and subcortical regions. IL-1Ra infusions reduced circulating cytokines and improved recovery of EEG activity and carotid artery perfusion. Histologically, IL-1Ra reduced microgliosis, IL-1β expression and caspase-3+ cells, and improved olig-2+ oligodendrocyte survival. Conclusion IL-1Ra improved EEG activity and markedly attenuated systemic inflammation, microgliosis and oligodendrocyte loss following LPS exposure in near-term fetal sheep. Further studies examining the long-term effects on brain maturation are now needed. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02238-4.
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Affiliation(s)
- Sharmony B Kelly
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Vanesa Stojanovska
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Valerie A Zahra
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Alison Moxham
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Timothy J M Moss
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Stuart B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Marcel F Nold
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Paediatrics, Monash University, Melbourne, Victoria, Australia.,Monash Newborn, Monash Children's Hospital, Melbourne, Australia
| | - Claudia A Nold-Petry
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Paediatrics, Monash University, Melbourne, Victoria, Australia
| | - Justin M Dean
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Graeme R Polglase
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Robert Galinsky
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia. .,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia.
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Cho KH, Fraser M, Xu B, Dean JM, Gunn AJ, Bennet L. Induction of Tertiary Phase Epileptiform Discharges after Postasphyxial Infusion of a Toll-Like Receptor 7 Agonist in Preterm Fetal Sheep. Int J Mol Sci 2021; 22:ijms22126593. [PMID: 34205464 PMCID: PMC8234830 DOI: 10.3390/ijms22126593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 01/30/2023] Open
Abstract
Background: Toll-like receptor (TLR) agonists are key immunomodulatory factors that can markedly ameliorate or exacerbate hypoxic–ischemic brain injury. We recently demonstrated that central infusion of the TLR7 agonist Gardiquimod (GDQ) following asphyxia was highly neuroprotective after 3 days but not 7 days of recovery. We hypothesize that this apparent transient neuroprotection is associated with modulation of seizure-genic processes and hemodynamic control. Methods: Fetuses received sham asphyxia or asphyxia induced by umbilical cord occlusion (20.9 ± 0.5 min) and were monitored continuously for 7 days. GDQ 3.34 mg or vehicle were infused intracerebroventricularly from 1 to 4 h after asphyxia. Results: GDQ infusion was associated with sustained moderate hypertension that resolved after 72 h recovery. Electrophysiologically, GDQ infusion was associated with reduced number and burden of postasphyxial seizures in the first 18 h of recovery (p < 0.05). Subsequently, GDQ was associated with induction of slow rhythmic epileptiform discharges (EDs) from 72 to 96 h of recovery (p < 0.05 vs asphyxia + vehicle). The total burden of EDs was associated with reduced numbers of neurons in the caudate nucleus (r2 = 0.61, p < 0.05) and CA1/2 hippocampal region (r2 = 0.66, p < 0.05). Conclusion: These data demonstrate that TLR7 activation by GDQ modulated blood pressure and suppressed seizures in the early phase of postasphyxial recovery, with subsequent prolonged induction of epileptiform activity. Speculatively, this may reflect delayed loss of early protection or contribute to differential neuronal survival in subcortical regions.
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Affiliation(s)
- Kenta H.T. Cho
- The Department of Physiology, The University of Auckland, Auckland 1023, New Zealand; (K.H.T.C.); (M.F.); (J.M.D.); (L.B.)
| | - Mhoyra Fraser
- The Department of Physiology, The University of Auckland, Auckland 1023, New Zealand; (K.H.T.C.); (M.F.); (J.M.D.); (L.B.)
| | - Bing Xu
- Shenzhen Bay Laboratory, Shenzhen 518118, China;
| | - Justin M. Dean
- The Department of Physiology, The University of Auckland, Auckland 1023, New Zealand; (K.H.T.C.); (M.F.); (J.M.D.); (L.B.)
| | - Alistair J. Gunn
- The Department of Physiology, The University of Auckland, Auckland 1023, New Zealand; (K.H.T.C.); (M.F.); (J.M.D.); (L.B.)
- Correspondence: ; Tel.: +64-9-373-7499
| | - Laura Bennet
- The Department of Physiology, The University of Auckland, Auckland 1023, New Zealand; (K.H.T.C.); (M.F.); (J.M.D.); (L.B.)
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10
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Prasad JD, van de Looij Y, Gunn KC, Ranchhod SM, White PB, Berry MJ, Bennet L, Sizonenko SV, Gunn AJ, Dean JM. Long-term coordinated microstructural disruptions of the developing neocortex and subcortical white matter after early postnatal systemic inflammation. Brain Behav Immun 2021; 94:338-356. [PMID: 33307171 DOI: 10.1016/j.bbi.2020.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 11/16/2020] [Accepted: 12/06/2020] [Indexed: 12/21/2022] Open
Abstract
Severe postnatal systemic infection is highly associated with persistent disturbances in brain development and neurobehavioral outcomes in survivors of preterm birth. However, the contribution of less severe but prolonged postnatal infection and inflammation to such disturbances is unclear. Further, the ability of modern imaging techniques to detect the underlying changes in cellular microstructure of the brain in these infants remains to be validated. We used high-field ex-vivo MRI, neurohistopathology, and behavioral tests in newborn rats to demonstrate that prolonged postnatal systemic inflammation causes subtle, persisting disturbances in brain development, with neurodevelopmental delays and mild motor impairments. Diffusion-tensor MRI and neurite orientation dispersion and density imaging (NODDI) revealed delayed maturation of neocortical and subcortical white matter microstructure. Analysis of pyramidal neurons showed that the cortical deficits involved impaired dendritic arborization and spine formation. Analysis of oligodendrocytes showed that the white matter deficits involved impaired oligodendrocyte maturation and axonal myelination. These findings indicate that prolonged postnatal inflammation, without severe infection, may critically contribute to the diffuse spectrum of brain pathology and subtle long-term disability in preterm infants, with a cellular mechanism involving oligodendrocyte and neuronal dysmaturation. NODDI may be useful for clinical detection of these microstructural deficits.
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Affiliation(s)
- Jaya D Prasad
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Yohan van de Looij
- Division of Child Development and Growth, Department of Pediatrics and Gynecology Obstetrics, University of Geneva, Geneva, Switzerland; Center for Biomedical Imaging - Animal Imaging and Technology, Lausanne Federal Polytechnic School, Lausanne, Switzerland
| | - Katherine C Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Sonya M Ranchhod
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Petra B White
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Mary J Berry
- The Department of Pediatrics and Health Care, University of Otago, New Zealand
| | - Laura Bennet
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Stéphane V Sizonenko
- Division of Child Development and Growth, Department of Pediatrics and Gynecology Obstetrics, University of Geneva, Geneva, Switzerland
| | - Alistair J Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand.
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11
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Prasad JD, Gunn KC, Davidson JO, Galinsky R, Graham SE, Berry MJ, Bennet L, Gunn AJ, Dean JM. Anti-Inflammatory Therapies for Treatment of Inflammation-Related Preterm Brain Injury. Int J Mol Sci 2021; 22:4008. [PMID: 33924540 PMCID: PMC8069827 DOI: 10.3390/ijms22084008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/09/2021] [Accepted: 04/10/2021] [Indexed: 12/13/2022] Open
Abstract
Despite the prevalence of preterm brain injury, there are no established neuroprotective strategies to prevent or alleviate mild-to-moderate inflammation-related brain injury. Perinatal infection and inflammation have been shown to trigger acute neuroinflammation, including proinflammatory cytokine release and gliosis, which are associated with acute and chronic disturbances in brain cell survival and maturation. These findings suggest the hypothesis that the inhibition of peripheral immune responses following infection or nonspecific inflammation may be a therapeutic strategy to reduce the associated brain injury and neurobehavioral deficits. This review provides an overview of the neonatal immunity, neuroinflammation, and mechanisms of inflammation-related brain injury in preterm infants and explores the safety and efficacy of anti-inflammatory agents as potentially neurotherapeutics.
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Affiliation(s)
- Jaya D. Prasad
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand; (J.D.P.); (K.C.G.); (J.O.D.); (L.B.); (A.J.G.)
| | - Katherine C. Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand; (J.D.P.); (K.C.G.); (J.O.D.); (L.B.); (A.J.G.)
| | - Joanne O. Davidson
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand; (J.D.P.); (K.C.G.); (J.O.D.); (L.B.); (A.J.G.)
| | - Robert Galinsky
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia;
| | - Scott E. Graham
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1010, New Zealand;
| | - Mary J. Berry
- Department of Pediatrics and Health Care, University of Otago, Dunedin 9016, New Zealand;
| | - Laura Bennet
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand; (J.D.P.); (K.C.G.); (J.O.D.); (L.B.); (A.J.G.)
| | - Alistair J. Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand; (J.D.P.); (K.C.G.); (J.O.D.); (L.B.); (A.J.G.)
| | - Justin M. Dean
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1010, New Zealand; (J.D.P.); (K.C.G.); (J.O.D.); (L.B.); (A.J.G.)
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12
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Morrison JL, Ayonrinde OT, Care AS, Clarke GD, Darby JRT, David AL, Dean JM, Hooper SB, Kitchen MJ, Macgowan CK, Melbourne A, McGillick EV, McKenzie CA, Michael N, Mohammed N, Sadananthan SA, Schrauben E, Regnault TRH, Velan SS. Seeing the fetus from a DOHaD perspective: discussion paper from the advanced imaging techniques of DOHaD applications workshop held at the 2019 DOHaD World Congress. J Dev Orig Health Dis 2021; 12:153-167. [PMID: 32955011 DOI: 10.1017/s2040174420000884] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Advanced imaging techniques are enhancing research capacity focussed on the developmental origins of adult health and disease (DOHaD) hypothesis, and consequently increasing awareness of future health risks across various subareas of DOHaD research themes. Understanding how these advanced imaging techniques in animal models and human population studies can be both additively and synergistically used alongside traditional techniques in DOHaD-focussed laboratories is therefore of great interest. Global experts in advanced imaging techniques congregated at the advanced imaging workshop at the 2019 DOHaD World Congress in Melbourne, Australia. This review summarizes the presentations of new imaging modalities and novel applications to DOHaD research and discussions had by DOHaD researchers that are currently utilizing advanced imaging techniques including MRI, hyperpolarized MRI, ultrasound, and synchrotron-based techniques to aid their DOHaD research focus.
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Affiliation(s)
- Janna L Morrison
- Early Origins of Adult Health Research Group, Health and Biomedical Innovation, UniSA: Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Oyekoya T Ayonrinde
- Fiona Stanley Hospital, Murdoch, WA, Australia
- Medical School, The University of Western Australia, Perth, WA, Australia
| | - Alison S Care
- The Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Geoffrey D Clarke
- Department of Radiology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jack R T Darby
- Early Origins of Adult Health Research Group, Health and Biomedical Innovation, UniSA: Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Anna L David
- Elizabeth Garrett Anderson Institute for Women's Health, University College London, London, UK
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Stuart B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- The Department of Obstetrics and Gynecology, Monash University, Melbourne, Victoria, Australia
| | - Marcus J Kitchen
- School of Physics and Astronomy, Monash University, Melbourne, Victoria, Australia
| | | | - Andrew Melbourne
- School of Biomedical Engineering and Imaging Sciences, Kings College London, London, UK
| | - Erin V McGillick
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
- The Department of Obstetrics and Gynecology, Monash University, Melbourne, Victoria, Australia
| | - Charles A McKenzie
- Department of Medical Biophysics, Western University, London, ON, Canada
- Lawson Health Research Institute and Children's Health Research Institute, London, ON, Canada
| | - Navin Michael
- Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research (A*STAR), Singapore, Singapore
| | - Nuruddin Mohammed
- Maternal Fetal Medicine Unit, Department of Obstetrics and Gynecology, Aga Khan University Hospital, Karachi, Pakistan
| | - Suresh Anand Sadananthan
- Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research (A*STAR), Singapore, Singapore
| | - Eric Schrauben
- Translational Medicine, Hospital for Sick Children, Toronto, ON, Canada
| | - Timothy R H Regnault
- Lawson Health Research Institute and Children's Health Research Institute, London, ON, Canada
- Department of Obstetrics and Gynecology, Western University, London, ON, Canada
- Department of Physiology and Pharmacology, Western University, London, ON, Canada
| | - S Sendhil Velan
- Singapore Bioimaging Consortium, Agency for Science, Technology, and Research (A*STAR), Singapore, Singapore
- Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research (A*STAR), Singapore, Singapore
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13
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Galinsky R, van de Looij Y, Mitchell N, Dean JM, Dhillon SK, Yamaguchi K, Lear CA, Wassink G, Davidson JO, Nott F, Zahra VA, Kelly SB, King VJ, Sizonenko SV, Bennet L, Gunn AJ. Magnetic Resonance Imaging Correlates of White Matter Gliosis and Injury in Preterm Fetal Sheep Exposed to Progressive Systemic Inflammation. Int J Mol Sci 2020; 21:ijms21238891. [PMID: 33255257 PMCID: PMC7727662 DOI: 10.3390/ijms21238891] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/17/2020] [Accepted: 11/19/2020] [Indexed: 12/17/2022] Open
Abstract
Progressive fetal infection/inflammation is strongly associated with neural injury after preterm birth. We aimed to test the hypotheses that progressively developing fetal inflammation leads to neuroinflammation and impaired white matter development and that the histopathological changes can be detected using high-field diffusion tensor magnetic resonance imaging (MRI). Chronically instrumented preterm fetal sheep at 0.7 of gestation were randomly assigned to receive intravenous saline (control; n = 6) or a progressive infusion of lipopolysaccharide (LPS, 200 ng intravenous over 24 h then doubled every 24 h for 5 days to induce fetal inflammation, n = 7). Sheep were killed 10 days after starting the infusions, for histology and high-field diffusion tensor MRI. Progressive LPS infusion was associated with increased circulating interleukin (IL)-6 concentrations and moderate increases in carotid artery perfusion and the frequency of electroencephalogram (EEG) activity (p < 0.05 vs. control). In the periventricular white matter, fractional anisotropy (FA) was increased, and orientation dispersion index (ODI) was reduced (p < 0.05 vs. control for both). Histologically, in the same brain region, LPS infusion increased microglial activation and astrocyte numbers and reduced the total number of oligodendrocytes with no change in myelination or numbers of immature/mature oligodendrocytes. Numbers of astrocytes in the periventricular white matter were correlated with increased FA and reduced ODI signal intensities. Astrocyte coherence was associated with increased FA. Moderate astrogliosis, but not loss of total oligodendrocytes, after progressive fetal inflammation can be detected with high-field diffusion tensor MRI.
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Affiliation(s)
- Robert Galinsky
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria 3168, Australia; (F.N.); (V.A.Z.); (S.B.K.)
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria 3800, Australia
| | - Yohan van de Looij
- Division of Child Development & Growth, Department of Pediatrics, Gynaecology & Obstetrics, School of Medicine, University of Geneva, 1015 Geneva, Switzerland; (Y.v.d.L.); (S.V.S.)
| | - Natasha Mitchell
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Justin M. Dean
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Simerdeep K. Dhillon
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Kyohei Yamaguchi
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Christopher A. Lear
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Guido Wassink
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Joanne O. Davidson
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Fraser Nott
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria 3168, Australia; (F.N.); (V.A.Z.); (S.B.K.)
| | - Valerie A. Zahra
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria 3168, Australia; (F.N.); (V.A.Z.); (S.B.K.)
| | - Sharmony B. Kelly
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria 3168, Australia; (F.N.); (V.A.Z.); (S.B.K.)
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria 3800, Australia
| | - Victoria J. King
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Stéphane V. Sizonenko
- Division of Child Development & Growth, Department of Pediatrics, Gynaecology & Obstetrics, School of Medicine, University of Geneva, 1015 Geneva, Switzerland; (Y.v.d.L.); (S.V.S.)
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
| | - Alistair J. Gunn
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand; (R.G.); (N.M.); (J.M.D.); (S.K.D.); (K.Y.); (C.A.L.); (G.W.); (J.O.D.); (V.J.K.); (L.B.)
- Correspondence:
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14
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Zhou KQ, Draghi V, Lear CA, Dean JM, Ashton JL, Hou Y, Bennet L, Gunn AJ, Davidson JO. Protection of axonal integrity with 48 or 72 h of cerebral hypothermia in near-term fetal sheep. Pediatr Res 2020; 88:48-56. [PMID: 31234193 DOI: 10.1038/s41390-019-0475-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/06/2019] [Accepted: 06/08/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND Therapeutic hypothermia is partially protective for neonatal hypoxic-ischemic encephalopathy (HIE). Damage to the white matter tracts is highly associated with adverse outcomes after HIE, but the effectiveness and optimal duration of hypothermia to attenuate axonal injury are unclear. METHODS Near-term fetal sheep were randomized to sham control or cerebral ischemia for 30 min with normothermia or cerebral hypothermia from 3 to either 48 or 72 h. Sheep were killed after 7 days. SMI-312-labeled axons and myelin basic protein were quantified in the intragyral white matter of the first and second parasagittal gyri. RESULTS Ischemia was associated with reduced axonal and myelin area fraction (p < 0.05); loss of axonal and myelin linearity (p < 0.05); and thin, sparse axons, with spheroids, compared to dense, linear morphology in sham controls and associated with induction of microglia in an amoeboid morphology. Both ischemia-48 h hypothermia and ischemia-72 h hypothermia improved axonal area fraction and linearity (p < 0.05), although abnormal morphological features were seen in a subset. Microglial induction was partially suppressed by ischemia-48 h hypothermia, with a ramified morphology. CONCLUSIONS These data suggest that therapeutic hypothermia can alleviate post-ischemic axonopathy, in part by suppressing secondary inflammation.
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Affiliation(s)
- Kelly Q Zhou
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Vittoria Draghi
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Christopher A Lear
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Jesse L Ashton
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Yufeng Hou
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Laura Bennet
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
| | - Joanne O Davidson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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15
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Cho KH, Davidson JO, Dean JM, Bennet L, Gunn AJ. Cooling and immunomodulation for treating hypoxic-ischemic brain injury. Pediatr Int 2020; 62:770-778. [PMID: 32119180 DOI: 10.1111/ped.14215] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 02/20/2020] [Accepted: 02/27/2020] [Indexed: 12/20/2022]
Abstract
Therapeutic hypothermia is now well established to partially reduce disability in term and near-term infants with moderate-severe hypoxic-ischemic encephalopathy. Preclinical and clinical studies have confirmed that current protocols for therapeutic hypothermia are near optimal. The challenge is now to identify complementary therapies that can further improve outcomes, in combination with therapeutic hypothermia. Overall, anti-excitatory and anti-apoptotic agents have shown variable or even no benefit in combination with hypothermia, suggesting overlapping mechanisms of neuroprotection. Inflammation appears to play a critical role in the pathogenesis of injury in the neonatal brain, and thus, there is potential for drugs with immunomodulatory properties that target inflammation to be used as a therapy in neonates. In this review, we examine the evidence for neuroprotection with immunomodulation after hypoxia-ischemia. For example, stem cell therapy can reduce inflammation, increase cell survival, and promote cell maturation and repair. There are also encouraging preclinical data from small animals suggesting that stem cell therapy can augment hypothermic neuroprotection. However, there is conflicting evidence, and rigorous testing in translational animal models is now needed.
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Affiliation(s)
- Kenta Ht Cho
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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16
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Galinsky R, Dean JM, Lingam I, Robertson NJ, Mallard C, Bennet L, Gunn AJ. A Systematic Review of Magnesium Sulfate for Perinatal Neuroprotection: What Have We Learnt From the Past Decade? Front Neurol 2020; 11:449. [PMID: 32536903 PMCID: PMC7267212 DOI: 10.3389/fneur.2020.00449] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/28/2020] [Indexed: 12/14/2022] Open
Abstract
There is an important unmet need to improve long term outcomes of encephalopathy for preterm and term infants. Meta-analyses of large controlled trials suggest that maternal treatment with magnesium sulfate (MgSO4) is associated with a reduced risk of cerebral palsy and gross motor dysfunction after premature birth. However, to date, follow up to school age has found an apparent lack of long-term clinical benefit. Because of this inconsistency, it remains controversial whether MgSO4 offers sustained neuroprotection. We systematically reviewed preclinical and clinical studies reported from January 1 2010, to January 31 2020 to evaluate the most recent advances and knowledge gaps relating to the efficacy of MgSO4 for the treatment of perinatal brain injury. The outcomes of MgSO4 in preterm and term-equivalent animal models of perinatal encephalopathy were highly inconsistent between studies. None of the perinatal rodent studies that suggested benefit directly controlled body or brain temperature. The majority of the studies did not control for sex, study long term histological and functional outcomes or use pragmatic treatment regimens and many did not report controlling for potential study bias. Finally, most of the recent preterm or term human studies that tested the potential of MgSO4 for perinatal neuroprotection were relatively underpowered, but nevertheless, suggest that any improvements in neurodevelopment were at best modest or absent. On balance, these data suggest that further rigorous testing in translational preclinical models of perinatal encephalopathy is essential to ensure safety and best regimens for optimal preterm neuroprotection, and before further clinical trials of MgSO4 for perinatal encephalopathy at term are undertaken.
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Affiliation(s)
- Robert Galinsky
- Department of Obstetrics and Gynecology, The Ritchie Centre, Hudson Institute of Medical Research, Monash University, Melbourne, VIC, Australia.,Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Ingran Lingam
- Neonatology, Institute for Women's Health, University College London, London, United Kingdom
| | - Nicola J Robertson
- Neonatology, Institute for Women's Health, University College London, London, United Kingdom
| | - Carina Mallard
- Department of Neuroscience and Physiology, University of Gothenburg, Sahlgrenska Academy, Gothenburg, Sweden
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
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17
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Galinsky R, Dhillon SK, Dean JM, Davidson JO, Lear CA, Wassink G, Nott F, Kelly SB, Fraser M, Yuill C, Bennet L, Gunn AJ. Tumor necrosis factor inhibition attenuates white matter gliosis after systemic inflammation in preterm fetal sheep. J Neuroinflammation 2020; 17:92. [PMID: 32293473 PMCID: PMC7087378 DOI: 10.1186/s12974-020-01769-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 03/09/2020] [Indexed: 12/21/2022] Open
Abstract
Background Increased circulating levels of tumor necrosis factor (TNF) are associated with greater risk of impaired neurodevelopment after preterm birth. In this study, we tested the hypothesis that systemic TNF inhibition, using the soluble TNF receptor Etanercept, would attenuate neuroinflammation in preterm fetal sheep exposed to lipopolysaccharide (LPS). Methods Chronically instrumented preterm fetal sheep at 0.7 of gestation were randomly assigned to receive saline (control; n = 7), LPS infusion (100 ng/kg i.v. over 24 h then 250 ng/kg/24 h for 96 h plus 1 μg LPS boluses at 48, 72, and 96 h, to induce inflammation; n = 8) or LPS plus two i.v. infusions of Etanercept (2 doses, 5 mg/kg infused over 30 min, 48 h apart) started immediately before LPS-exposure (n = 8). Sheep were killed 10 days after starting infusions, for histology. Results LPS boluses were associated with increased circulating TNF, interleukin (IL)-6 and IL-10, electroencephalogram (EEG) suppression, hypotension, tachycardia, and increased carotid artery perfusion (P < 0.05 vs. control). In the periventricular and intragyral white matter, LPS exposure increased gliosis, TNF-positive cells, total oligodendrocytes, and cell proliferation (P < 0.05 vs control), but did not affect myelin expression or numbers of neurons in the cortex and subcortical regions. Etanercept delayed the rise in circulating IL-6, prolonged the increase in IL-10 (P < 0.05 vs. LPS), and attenuated EEG suppression, hypotension, and tachycardia after LPS boluses. Histologically, Etanercept normalized LPS-induced gliosis, and increase in TNF-positive cells, proliferation, and total oligodendrocytes. Conclusion TNF inhibition markedly attenuated white matter gliosis but did not affect mature oligodendrocytes after prolonged systemic inflammation in preterm fetal sheep. Further studies of long-term brain maturation are now needed.
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Affiliation(s)
- Robert Galinsky
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand.,The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Simerdeep K Dhillon
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Joanne O Davidson
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Christopher A Lear
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Guido Wassink
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Fraser Nott
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Sharmony B Kelly
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Mhoyra Fraser
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Caroline Yuill
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Laura Bennet
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand
| | - Alistair Jan Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private bag 92019, Auckland, 1023, New Zealand.
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18
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Cho KHT, Fraser M, Wassink G, Dhillon SJ, Davidson JO, Dean JM, Gunn AJ, Bennet L. TLR7 agonist modulation of postasphyxial neurophysiological and cardiovascular adaptations in preterm fetal sheep. Am J Physiol Regul Integr Comp Physiol 2020; 318:R369-R378. [PMID: 31913689 DOI: 10.1152/ajpregu.00295.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of Toll-like receptors (TLRs) after hypoxic-ischemic brain injury can exacerbate injury but also alleviate cell loss, as recently demonstrated with the TLR7 agonist Gardiquimod (GDQ). However, TLR agonists also modulate vascular function and neuronal excitability. Thus, we examined the effects of TLR7 activation with GDQ on cardiovascular function and seizures after asphyxia in preterm fetal sheep at 0.7 gestation (104 days, term ∼147 days). Fetuses received sham asphyxia or asphyxia induced by umbilical cord occlusion for 25 min or asphyxia followed by a continuous intracerebroventricular infusion of 3.34 mg of GDQ from 1 to 4 h after asphyxia. Fetuses were monitored continuously for 72 h postasphyxia. GDQ treatment was associated with sustained, moderate hypertension for 72 h (P < 0.05), with a transient increase in heart rate. Electroencephalographic (EEG) power was suppressed for the entire postasphyxial period in both groups, whereas EEG spectral edge transiently increased during the GDQ infusion compared with asphyxia alone (P < 0.05), with higher β- and lower δ-EEG frequencies (P < 0.05). This increase in EEG frequency was not related to epileptiform activity. After the GDQ infusion, there was earlier onset of high-amplitude stereotypic evolving seizures, with increased numbers of seizures and seizure burden (P < 0.05). Hemodynamic function and seizure activity are important indices of preterm wellbeing. These data highlight the importance of physiological monitoring during preclinical testing of potential neuroprotective strategies.
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Affiliation(s)
- Kenta H T Cho
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Mhoyra Fraser
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | | | - Joanne O Davidson
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand
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19
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Dean JM, Levison SW. Preface. Dev Neurosci 2019; 40:381. [PMID: 31256168 DOI: 10.1159/000500983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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20
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Paton MCB, Allison BJ, Li J, Fahey MC, Sutherland AE, Nitsos I, Bischof RJ, Dean JM, Moss TJM, Polglase GR, Jenkin G, McDonald CA, Miller SL. Human Umbilical Cord Blood Therapy Protects Cerebral White Matter from Systemic LPS Exposure in Preterm Fetal Sheep. Dev Neurosci 2018; 40:258-270. [PMID: 30179864 DOI: 10.1159/000490943] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/15/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Infants born preterm following exposure to in utero inflammation/chorioamnionitis are at high risk of brain injury and life-long neurological deficits. In this study, we assessed the efficacy of early intervention umbilical cord blood (UCB) cell therapy in a large animal model of preterm brain inflammation and injury. We hypothesised that UCB treatment would be neuroprotective for the preterm brain following subclinical fetal inflammation. METHODS Chronically instrumented fetal sheep at 0.65 gestation were administered lipopolysaccharide (LPS, 150 ng, 055:B5) intravenously over 3 consecutive days, followed by 100 million human UCB mononuclear cells 6 h after the final LPS dose. Controls were administered saline instead of LPS and cells. Ten days after the first LPS dose, the fetal brain and cerebrospinal fluid were collected for analysis of subcortical and periventricular white matter injury and inflammation. RESULTS LPS administration increased microglial aggregate size, neutrophil recruitment, astrogliosis and cell death compared with controls. LPS also reduced total oligodendrocyte count and decreased mature myelinating oligodendrocytes. UCB cell therapy attenuated cell death and inflammation, and recovered total and mature oligodendrocytes, compared with LPS. CONCLUSIONS UCB cell treatment following inflammation reduces preterm white matter brain injury, likely mediated via anti-inflammatory actions.
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Affiliation(s)
- Madison C B Paton
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Beth J Allison
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Jingang Li
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Michael C Fahey
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Paediatrics, Monash Children's, Monash Health, Clayton, Victoria, Australia
| | - Amy E Sutherland
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Ilias Nitsos
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Robert J Bischof
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Timothy J M Moss
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Graeme R Polglase
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Graham Jenkin
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Courtney A McDonald
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
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21
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Joss-Moore LA, Keenan HT, Bale JF, Dean JM, Albertine KH. A Pediatric Department's Innovative Grant Writing Workshops. J Pediatr 2018; 197:5-7.e1. [PMID: 29801547 PMCID: PMC7147830 DOI: 10.1016/j.jpeds.2018.02.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 02/26/2018] [Indexed: 11/24/2022]
Affiliation(s)
- LA Joss-Moore
- Department of Pediatrics, University of Utah, School of Medicine, Salt Lake City, Utah
| | - HT Keenan
- Department of Pediatrics, University of Utah, School of Medicine, Salt Lake City, Utah
| | - JF Bale
- Department of Pediatrics, University of Utah, School of Medicine, Salt Lake City, Utah
| | - JM Dean
- Department of Pediatrics, University of Utah, School of Medicine, Salt Lake City, Utah
| | - KH Albertine
- Department of Pediatrics, University of Utah, School of Medicine, Salt Lake City, Utah,Corresponding Author: Kurt H Albertine, Ph.D., Williams Bldg, Salt Lake City, Utah 84108, TEL: (801) 581-4178, FAX: (801) 585-7395,
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22
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Davidson JO, Dean JM, Fraser M, Wassink G, Andelius TC, Dhillon SK, Bennet L, Gunn AJ. Perinatal brain injury: mechanisms and therapeutic approaches. Front Biosci (Landmark Ed) 2018; 23:2204-2226. [PMID: 29772556 DOI: 10.2741/4700] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brain damage resulting from perinatal hypoxia-ischemia evolves slowly over time. While a small number of brain cells may die during a sufficiently profound period of hypoxia-ischemia, many will show initial recovery during a "latent" phase characterized by actively suppressed neural metabolism and activity. Critically, this transient recovery may be followed after ~6 hours by a phase of secondary deterioration, with delayed seizures, failure of mitochondrial function, cytotoxic edema, and bulk cell death over ~72 hours. This is followed by a tertiary phase of remodeling and recovery. Understanding the mechanisms of injury that occur during each phase may allow for the development of more targeted treatments. This review discusses the mechanisms of injury that occur during the primary, latent, secondary and tertiary phases of injury and potential treatments that target one or more of these phases. Treatment during the latent phase has the greatest potential to prevent injury. In the secondary phase of injury, anticonvulsants can attenuate seizures but show limited neuroprotection. By contrast, there is increasing preclinical evidence that neurorestorative therapies may improve long-term outcomes.
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Affiliation(s)
- Joanne O Davidson
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand
| | - Justin M Dean
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand
| | - Mhoyra Fraser
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand
| | - Guido Wassink
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand
| | - Ted C Andelius
- Department of Paediatrics and Adolescent Medicine, Aarhus University Hospital, Denmark
| | - Simerdeep K Dhillon
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand
| | - Laura Bennet
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand
| | - Alistair Jan Gunn
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 2013, New Zealand,
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23
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Dieriks BV, Dean JM, Aronica E, Waldvogel HJ, Faull RLM, Curtis MA. Differential Fatty Acid-Binding Protein Expression in Persistent Radial Glia in the Human and Sheep Subventricular Zone. Dev Neurosci 2018; 40:145-161. [PMID: 29680832 DOI: 10.1159/000487633] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 01/18/2018] [Indexed: 01/19/2023] Open
Abstract
Fatty acid-binding proteins (FABPs) are a family of transport proteins that facilitate intracellular transport of fatty acids. Despite abundant expression in the brain, the role that FABPs play in the process of cell proliferation and migration in the subventricular zone (SVZ) remains unclear. Our results provide a detailed characterisation of FABP3, 5, and 7 expression in adult and fetal human and sheep SVZ. High FABP5 expression was specifically observed in the adult human SVZ and co-labelled with polysialylated neural cell adhesion molecule (PSA-NCAM), glial fibrillary acidic protein (GFAP), GFAPδ, and proliferating cell nuclear antigen (PCNA), indicating a role for FABP5 throughout the full maturation process of astrocytes and neuroblasts. Some FABP5+ cells had a radial glial-like appearance and co-labelled with the radial glia markers vimentin (40E-C) and GFAP. In the fetal human brain, FABP5 was expressed by radial glia cells throughout the ventricular zone. In contrast, radial glia-like cells in sheep highly expressed FABP3. Taken together, these differences highlight the species-specific expression profile of FABPs in the SVZ. In this study, we demonstrate the distribution of FABP in the adult human SVZ and fetal ventricular zone and reveal its expression on persistent radial glia that may be involved in adult neurogenesis.
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Affiliation(s)
- Birger Victor Dieriks
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, Amsterdam, the Netherlands
| | - Henry J Waldvogel
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
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24
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Srivastava T, Diba P, Dean JM, Banine F, Shaver D, Hagen M, Gong X, Su W, Emery B, Marks DL, Harris EN, Baggenstoss B, Weigel PH, Sherman LS, Back SA. A TLR/AKT/FoxO3 immune tolerance-like pathway disrupts the repair capacity of oligodendrocyte progenitors. J Clin Invest 2018; 128:2025-2041. [PMID: 29664021 DOI: 10.1172/jci94158] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 02/28/2018] [Indexed: 12/12/2022] Open
Abstract
Cerebral white matter injury (WMI) persistently disrupts myelin regeneration by oligodendrocyte progenitor cells (OPCs). We identified a specific bioactive hyaluronan fragment (bHAf) that downregulates myelin gene expression and chronically blocks OPC maturation and myelination via a tolerance-like mechanism that dysregulates pro-myelination signaling via AKT. Desensitization of AKT occurs via TLR4 but not TLR2 or CD44. OPC differentiation was selectively blocked by bHAf in a maturation-dependent fashion at the late OPC (preOL) stage by a noncanonical TLR4/TRIF pathway that induced persistent activation of the FoxO3 transcription factor downstream of AKT. Activated FoxO3 selectively localized to oligodendrocyte lineage cells in white matter lesions from human preterm neonates and adults with multiple sclerosis. FoxO3 constraint of OPC maturation was bHAf dependent, and involved interactions at the FoxO3 and MBP promoters with the chromatin remodeling factor Brg1 and the transcription factor Olig2, which regulate OPC differentiation. WMI has adapted an immune tolerance-like mechanism whereby persistent engagement of TLR4 by bHAf promotes an OPC niche at the expense of myelination by engaging a FoxO3 signaling pathway that chronically constrains OPC differentiation.
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Affiliation(s)
- Taasin Srivastava
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Parham Diba
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Justin M Dean
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Fatima Banine
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon, USA
| | - Daniel Shaver
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Matthew Hagen
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Xi Gong
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Weiping Su
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon, USA
| | - Ben Emery
- Department of Neurology, OHSU, Portland, Oregon, USA
| | - Daniel L Marks
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Edward N Harris
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Bruce Baggenstoss
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Paul H Weigel
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Larry S Sherman
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon, USA.,Department of Cell, Developmental and Cancer Biology, OHSU, Portland, Oregon, USA
| | - Stephen A Back
- Department of Pediatrics, Oregon Health & Science University (OHSU), Portland, Oregon, USA.,Department of Neurology, OHSU, Portland, Oregon, USA
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25
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Galinsky R, Lear CA, Dean JM, Wassink G, Dhillon SK, Fraser M, Davidson JO, Bennet L, Gunn AJ. Complex interactions between hypoxia-ischemia and inflammation in preterm brain injury. Dev Med Child Neurol 2018; 60:126-133. [PMID: 29194585 DOI: 10.1111/dmcn.13629] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/17/2017] [Indexed: 12/12/2022]
Abstract
UNLABELLED Children surviving preterm birth have a high risk of disability, particularly cognitive and learning problems. There is extensive clinical and experimental evidence that disability is now primarily related to dysmaturation of white and gray matter, defined by failure of oligodendrocyte maturation and neuronal dendritic arborization, rather than cell death alone. The etiology of this dysmaturation is multifactorial, with contributions from hypoxia-ischemia, infection/inflammation and barotrauma. Intriguingly, these factors can interact to both increase and decrease damage. In this review we summarize preclinical and clinical evidence that all of these factors trigger secondary or chronic inflammation and gliosis. Thus, we hypothesize that these shared pathological features play a key role in a final common pathway that leads to the impaired neural maturation and connectivity and cognitive/motor impairments that are commonly observed in infants born preterm. This raises the possibility that secondary or chronic inflammation may be a viable therapeutic target for delayed interventions to improve neurodevelopmental outcomes after preterm birth. WHAT THIS PAPER ADDS Hypoxia-ischemia, infection/inflammation, and barotrauma/volutrauma all contribute to preterm brain injury. Multiple different triggers of preterm brain injury are associated with central nervous system dysmaturation. Secondary brain inflammation may be a viable target to improve neurodevelopment after preterm birth.
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Affiliation(s)
- Robert Galinsky
- The Department of Physiology, University of Auckland, Auckland, New Zealand.,The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Christopher A Lear
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | | | - Mhoyra Fraser
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- The Department of Physiology, University of Auckland, Auckland, New Zealand
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26
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Bennet L, Dhillon S, Lear CA, van den Heuij L, King V, Dean JM, Wassink G, Davidson JO, Gunn AJ. Chronic inflammation and impaired development of the preterm brain. J Reprod Immunol 2018; 125:45-55. [DOI: 10.1016/j.jri.2017.11.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 11/13/2017] [Accepted: 11/24/2017] [Indexed: 12/17/2022]
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27
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Abstract
Perinatal encephalopathy remains a major cause of disability, such as cerebral palsy. Therapeutic hypothermia is now well established to partially reduce risk of disability in late preterm/term infants. However, new and complementary therapeutic targets are needed to further improve outcomes. There is increasing evidence that glia play a key role in neural damage after hypoxia-ischemia and infection/inflammation. In this review, we discuss the role of astrocytic gap junction (connexin) hemichannels in the spread of neural injury after hypoxia-ischemia and/or infection/inflammation. Potential mechanisms of hemichannel mediated injury likely involve impaired intracellular calcium handling, loss of blood-brain barrier integrity and release of adenosine triphosphate (ATP) resulting in over-activation of purinergic receptors. We propose the hypothesis that inflammation-induced opening of connexin hemichannels is a key regulating event that initiates a vicious cycle of excessive ATP release, which in turn propagates activation of purinergic receptors on microglia and astrocytes. This suggests that developing new neuroprotective strategies for preterm infants will benefit from a detailed understanding of glial and connexin hemichannel responses.
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Affiliation(s)
- Robert Galinsky
- Department of Physiology, University of Auckland, Auckland, New Zealand; The Ritchie Centre, Hudson Institute of Medical Research, Victoria, Australia
| | - Joanne O Davidson
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
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28
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Fowke TM, Karunasinghe RN, Bai JZ, Jordan S, Gunn AJ, Dean JM. Hyaluronan synthesis by developing cortical neurons in vitro. Sci Rep 2017; 7:44135. [PMID: 28287145 PMCID: PMC5347017 DOI: 10.1038/srep44135] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 02/03/2017] [Indexed: 12/31/2022] Open
Abstract
Hyaluronan is a linear glycosaminoglycan that forms the backbone of perineuronal nets around neurons in the cerebral cortex. However, it remains controversial whether neurons are capable of independent hyaluronan synthesis. Herein, we examined the expression of hyaluronan and hyaluronan synthases (HASs) throughout cortical neuron development in vitro. Enriched cultures of cortical neurons were established from E16 rats. Neurons were collected at days in vitro (DIV) 0 (4 h), 1, 3, 7, 14, and 21 for qPCR or immunocytochemistry. In the relative absence of glia, neurons exhibited HAS1–3 mRNA at all time-points. By immunocytochemistry, puncta of HAS2–3 protein and hyaluronan were located on neuronal cell bodies, neurites, and lamellipodia/growth cones from as early as 4 h in culture. As neurons matured, hyaluronan was also detected on dendrites, filopodia, and axons, and around synapses. Percentages of hyaluronan-positive neurons increased with culture time to ~93% by DIV21, while only half of neurons at DIV21 expressed the perineuronal net marker Wisteria floribunda agglutinin. These data clearly demonstrate that neurons in vitro can independently synthesise hyaluronan throughout all maturational stages, and that hyaluronan production is not limited to neurons expressing perineuronal nets. The specific structural localisation of hyaluronan suggests potential roles in neuronal development and function.
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Affiliation(s)
- Tania M Fowke
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Rashika N Karunasinghe
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Ji-Zhong Bai
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Shawn Jordan
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
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29
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Galinsky R, Dean JM, Lear CA, Davidson JO, Dhillon S, Wassink G, Bennet L, Gunn AJ. In the Era of Therapeutic Hypothermia, How Well Do Studies of Perinatal Neuroprotection Control Temperature? Dev Neurosci 2016; 39:7-22. [PMID: 27988510 DOI: 10.1159/000452859] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 10/26/2016] [Indexed: 11/19/2022] Open
Abstract
In the era of therapeutic hypothermia, reliable preclinical studies are integral to successfully identify neuroprotective strategies to further improve outcomes of encephalopathy at term. We reviewed preclinical neuroprotection studies reported between January 2014 and June 2016 to assess the use of effective temperature monitoring and control. As a secondary measure, we examined whether studies addressed other methodological issues such as stage of brain development, sex differences, the timing of the treatment relative to the insult, and the histological and functional endpoints used after hypoxia-ischemia. The extent and duration of temperature monitoring was highly inconsistent. Only a minority of papers monitored core (19/61; 31%) or brain temperature (3/61; 5%). Most (40/45) of the neuroprotectants either were likely to affect thermoregulation or their impact is unknown. In 85% of papers neonatal rodents were used (67% at P7); 51% of papers did not report the sex of the animals or tested the effect of potential neuroprotectants on just one sex. In 76% of studies, treatment was before or immediately after the insult (within the first 2 h), and few studies assessed long-term histological and behavioral outcomes. In conclusion, many recent preclinical neonatal studies cannot exclude the possibility that apparent neuroprotection might be related to drug-induced hypothermia or to other methodological choices. Close monitoring and control of brain temperature during, as well as for many days after, experimental hypoxia-ischemia are now critical to reliably develop new ways to improve neurodevelopmental outcomes after perinatal hypoxic-ischemic encephalopathy.
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Affiliation(s)
- Robert Galinsky
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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30
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Bracciali C, Guzzo G, Giacoma C, Dean JM, Sarà G. Fish functional traits are affected by hydrodynamics at small spatial scale. Mar Environ Res 2016; 113:116-123. [PMID: 26707883 DOI: 10.1016/j.marenvres.2015.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 11/28/2015] [Accepted: 12/01/2015] [Indexed: 06/05/2023]
Abstract
The Mediterranean damselfish Chromis chromis is a species with a broad distribution found both in the Mediterranean Sea and Eastern Atlantic as far south as the coast of Angola. We hypothesized that the species may have significant functional morphological plasticity to adapt along a gradient of environmental conditions. It is a non-migratory zooplanktivorous species and spends the daytime searching for food in the middle of the water column. Therefore, local hydrodynamics could be one of the environmental factors affecting traits of C. chromis with repercussions at the population level. We compared the body condition, individual growth and body shapes of damselfish collected under two different hydrodynamic conditions (low ∼10 cm s(-1) vs. high ∼20 cm s(-1)). Specimens showed higher body condition under high-hydrodynamics, where conditions offered greater amounts of food, which were able to support larger individuals. Individuals smaller than 60-mm were more abundant under low-hydrodynamics. Morphometric analysis revealed that high-hydrodynamics were favored by fish with a more fusiform body shape and body traits developed for propellant swimming.
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Affiliation(s)
- C Bracciali
- Dipartimento di Scienze della Terra e del Mare, University of Palermo, Viale delle Scienze Ed. 16, 90128 Palermo, Italy; Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Turin, Italy
| | - G Guzzo
- Dipartimento di Scienze della Terra e del Mare, University of Palermo, Viale delle Scienze Ed. 16, 90128 Palermo, Italy
| | - C Giacoma
- Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Turin, Italy
| | - J M Dean
- Baruch Institute for Marine and Coastal Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - G Sarà
- Dipartimento di Scienze della Terra e del Mare, University of Palermo, Viale delle Scienze Ed. 16, 90128 Palermo, Italy; CoNISMa, UO-Palermo, Via Archirafi, 18, 90123 Palermo, Italy.
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Bennett TD, Dean JM, Keenan HT, McGlincy MH, Thomas AM, Cook LJ. Linked Records of Children with Traumatic Brain Injury. Probabilistic Linkage without Use of Protected Health Information. Methods Inf Med 2015; 54:328-37. [PMID: 26021580 DOI: 10.3414/me14-01-0093] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/15/2015] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Record linkage may create powerful datasets with which investigators can conduct comparative effectiveness studies evaluating the impact of tests or interventions on health. All linkages of health care data files to date have used protected health information (PHI) in their linkage variables. A technique to link datasets without using PHI would be advantageous both to preserve privacy and to increase the number of potential linkages. METHODS We applied probabilistic linkage to records of injured children in the National Trauma Data Bank (NTDB, N = 156,357) and the Pediatric Health Information Systems (PHIS, N = 104,049) databases from 2007 to 2010. 49 match variables without PHI were used, many of them administrative variables and indicators for procedures recorded as International Classification of Diseases, 9th revision, Clinical Modification codes. We validated the accuracy of the linkage using identified data from a single center that submits to both databases. RESULTS We accurately linked the PHIS and NTDB records for 69% of children with any injury, and 88% of those with severe traumatic brain injury eligible for a study of intervention effectiveness (positive predictive value of 98%, specificity of 99.99%). Accurate linkage was associated with longer lengths of stay, more severe injuries, and multiple injuries. CONCLUSION In populations with substantial illness or injury severity, accurate record linkage may be possible in the absence of PHI. This methodology may enable linkages and, in turn, comparative effectiveness studies that would be unlikely or impossible otherwise.
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Affiliation(s)
- T D Bennett
- Tellen D. Bennett, MD, MS, Pediatric Critical Care, University of Colorado School of Medicine, Children's Hospital Colorado, Adult and Child Center for Outcomes Research and Delivery Science (ACCORDS), 13199 E Montview Blvd, Suite 300, Campus Mail F443, Aurora, CO 80045, USA, E-mail:
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Abstract
Multiple randomized controlled trials have shown that prolonged, moderate cerebral hypothermia initiated within a few hours after severe hypoxia-ischemia and continued until resolution of the acute phase of delayed cell death reduces mortality and improves neurodevelopmental outcome in term infants. The challenge is now to find ways to further improve outcomes. In the present review, we critically examine the evidence that conventional analgesic, sedative, or anticonvulsant agents might improve outcomes, in relation to the known window of opportunity for effective protection with hypothermia. This review strongly indicates that there is insufficient evidence to recommend routine use of these agents during therapeutic hypothermia. Further systematic research into the effects of pain and stress on the injured brain, and their treatment during hypothermia, is essential to guide the rational development of clinical treatment protocols.
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Affiliation(s)
- Guido Wassink
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | | | - Katherine C Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand.
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van de Looij Y, Dean JM, Gunn AJ, Hüppi PS, Sizonenko SV. Advanced magnetic resonance spectroscopy and imaging techniques applied to brain development and animal models of perinatal injury. Int J Dev Neurosci 2015; 45:29-38. [PMID: 25818582 DOI: 10.1016/j.ijdevneu.2015.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/25/2015] [Accepted: 03/25/2015] [Indexed: 11/16/2022] Open
Abstract
Magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) are widely used in the field of brain development and perinatal brain injury. Due to technical progress the magnetic field strength (B0) of MR systems has continuously increased, favoring (1)H-MRS with quantification of up to 18 metabolites in the brain and short echo time (TE) MRI sequences including phase and susceptibility imaging. For longer TE techniques including diffusion imaging modalities, the benefits of higher B0 have not been clearly established. Nevertheless, progress has also been made in new advanced diffusion models that have been developed to enhance the accuracy and specificity of the derived diffusion parameters. In this review, we will describe the latest developments in MRS and MRI techniques, including high-field (1)H-MRS, phase and susceptibility imaging, and diffusion imaging, and discuss their application in the study of cerebral development and perinatal brain injury.
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Affiliation(s)
- Yohan van de Looij
- Division of Child Development & Growth, Department of Pediatrics, University of Geneva, Geneva, Switzerland; Laboratory for Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Petra S Hüppi
- Division of Child Development & Growth, Department of Pediatrics, University of Geneva, Geneva, Switzerland
| | - Stéphane V Sizonenko
- Division of Child Development & Growth, Department of Pediatrics, University of Geneva, Geneva, Switzerland
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Dean JM, Shi Z, Fleiss B, Gunn KC, Groenendaal F, van Bel F, Derrick M, Juul SE, Tan S, Gressens P, Mallard C, Bennet L, Gunn AJ. A Critical Review of Models of Perinatal Infection. Dev Neurosci 2015; 37:289-304. [DOI: 10.1159/000370309] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/02/2014] [Indexed: 11/19/2022] Open
Abstract
One of the central, unanswered questions in perinatology is why preterm infants continue to have such poor long-term neurodevelopmental, cognitive and learning outcomes, even though severe brain injury is now rare. There is now strong clinical evidence that one factor underlying disability may be infection, as well as nonspecific inflammation, during fetal and early postnatal life. In this review, we examine the experimental evidence linking both acute and chronic infection/inflammation with perinatal brain injury and consider key experimental determinants, including the microglia response, relative brain and immune maturity and the pattern of exposure to infection. We highlight the importance of the origin and derivation of the bacterial cell wall component lipopolysaccharide. Such experimental paradigms are essential to determine the precise time course of the inflammatory reaction and to design targeted neuroprotective strategies to protect the perinatal brain from infection and inflammation.
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Hagen MW, Riddle A, McClendon E, Gong X, Shaver D, Srivastava T, Dean JM, Bai JZ, Fowke TM, Gunn AJ, Jones DF, Sherman LS, Grafe MR, Hohimer AR, Back SA. Role of recurrent hypoxia-ischemia in preterm white matter injury severity. PLoS One 2014; 9:e112800. [PMID: 25390897 PMCID: PMC4229227 DOI: 10.1371/journal.pone.0112800] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/15/2014] [Indexed: 11/18/2022] Open
Abstract
Objective Although the spectrum of white matter injury (WMI) in preterm infants is shifting from cystic necrotic lesions to milder forms, the factors that contribute to this changing spectrum are unclear. We hypothesized that recurrent hypoxia-ischemia (rHI) will exacerbate the spectrum of WMI defined by markers of inflammation and molecules related to the extracellular matrix (hyaluronan (HA) and the PH20 hyaluronidase) that regulate maturation of the oligodendrocyte (OL) lineage after WMI. Methods We employed a preterm fetal sheep model of in utero moderate hypoxemia and global severe but not complete cerebral ischemia that reproduces the spectrum of human WMI. The response to rHI was compared against corresponding early or later single episodes of HI. An ordinal rating scale of WMI was compared against an unbiased quantitative image analysis protocol that provided continuous histo-pathological outcome measures for astrogliosis and microglial activation. Late oligodendrocyte progenitors (preOLs) were quantified by stereology. Analysis of hyaluronan and the hyaluronidase PH20 defined the progressive response of the extracellular matrix to WMI. Results rHI resulted in a more severe spectrum of WMI with a greater burden of necrosis, but an expanded population of preOLs that displayed reduced susceptibility to cell death. WMI from single episodes of HI or rHI was accompanied by elevated HA levels and increased labeling for PH20. Expression of PH20 in fetal ovine WMI was confirmed by RT-PCR and RNA-sequencing. Conclusions rHI is associated with an increased risk for more severe WMI with necrosis, but reduced risk for preOL degeneration compared to single episodes of HI. Expansion of the preOL pool may be linked to elevated hyaluronan and PH20.
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Affiliation(s)
- Matthew W. Hagen
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Art Riddle
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Evelyn McClendon
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Xi Gong
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Daniel Shaver
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Taasin Srivastava
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Justin M. Dean
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Ji-Zhong Bai
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Tania M. Fowke
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Alistair J. Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Daniel F. Jones
- New Zealand Genomics Ltd./Bioinformatics Institute, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Larry S. Sherman
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon, United States of America
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Marjorie R. Grafe
- Department of Pathology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - A. Roger Hohimer
- Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Stephen A. Back
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
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Thomas AM, Cook LJ, Dean JM, Olson LM. The utility of imputed matched sets. Analyzing probabilistically linked databases in a low information setting. Methods Inf Med 2014; 53:186-94. [PMID: 24728023 DOI: 10.3414/me13-01-0094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 02/18/2014] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To compare results from high probability matched sets versus imputed matched sets across differing levels of linkage information. METHODS A series of linkages with varying amounts of available information were performed on two simulated datasets derived from multiyear motor vehicle crash (MVC) and hospital databases, where true matches were known. Distributions of high probability and imputed matched sets were compared against the true match population for occupant age, MVC county, and MVC hour. Regression models were fit to simulated log hospital charges and hospitalization status. RESULTS High probability and imputed matched sets were not significantly different from occupant age, MVC county, and MVC hour in high information settings (p > 0.999). In low information settings, high probability matched sets were significantly different from occupant age and MVC county (p < 0.002), but imputed matched sets were not (p > 0.493). High information settings saw no significant differences in inference of simulated log hospital charges and hospitalization status between the two methods. High probability and imputed matched sets were significantly different from the outcomes in low information settings; however, imputed matched sets were more robust. CONCLUSIONS The level of information available to a linkage is an important consideration. High probability matched sets are suitable for high to moderate information settings and for situations involving case-specific analysis. Conversely, imputed matched sets are preferable for low information settings when conducting population-based analyses.
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Affiliation(s)
| | - L J Cook
- Lawrence J. Cook, University of Utah School of Medicine, Department of Pediatrics, P.O. Box 581289, Salt Lake City, Utah 84158-1289, USA, E-mail:
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McClendon E, Chen K, Gong X, Sharifnia E, Hagen M, Cai V, Shaver DC, Riddle A, Dean JM, Gunn AJ, Mohr C, Kaplan JS, Rossi DJ, Kroenke CD, Hohimer AR, Back SA. Prenatal cerebral ischemia triggers dysmaturation of caudate projection neurons. Ann Neurol 2014; 75:508-24. [PMID: 24395459 DOI: 10.1002/ana.24100] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/15/2013] [Accepted: 12/31/2013] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Recently, we reported that the neocortex displays impaired growth after transient cerebral hypoxia-ischemia (HI) at preterm gestation that is unrelated to neuronal death but is associated with decreased dendritic arbor complexity of cortical projection neurons. We hypothesized that these morphological changes constituted part of a more widespread neuronal dysmaturation response to HI in the caudate nucleus (CN), which contributes to motor and cognitive disability in preterm survivors. METHODS Ex vivo magnetic resonance imaging (MRI), immunohistochemistry, and Golgi staining defined CN growth, cell death, proliferation, and dendritic maturation in preterm fetal sheep 4 weeks after HI. Patch-clamp recording was used to analyze glutamatergic synaptic currents in CN neurons. RESULTS MRI-defined growth of the CN was reduced after ischemia compared to controls. However, no significant acute or delayed neuronal death was seen in the CN or white matter. Nor was there significant loss of calbindin-positive medium spiny projection neurons (MSNs) or CN interneurons expressing somatostatin, calretinin, parvalbumin, or tyrosine hydroxylase. Morphologically, ischemic MSNs showed a markedly immature dendritic arbor, with fewer dendritic branches, nodes, endings, and spines. The magnitude and kinetics of synaptic currents, and the relative contribution of glutamate receptor subtypes in the CN were significantly altered. INTERPRETATION The marked MSN dendritic and functional abnormalities after preterm cerebral HI, despite the marked resistance of immature CN neurons to cell death, are consistent with widespread susceptibility of projection neurons to HI-induced dysmaturation. These global disturbances in dendritic maturation and glutamatergic synaptic transmission suggest a new mechanism for long-term motor and behavioral disabilities in preterm survivors via widespread disruption of neuronal connectivity.
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Affiliation(s)
- Evelyn McClendon
- Department of Pediatrics, Oregon Health and Science University, Portland, OR
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Bennet L, Van Den Heuij L, M Dean J, Drury P, Wassink G, Jan Gunn A. Neural plasticity and the Kennard principle: does it work for the preterm brain? Clin Exp Pharmacol Physiol 2013; 40:774-84. [DOI: 10.1111/1440-1681.12135] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/29/2013] [Accepted: 05/31/2013] [Indexed: 12/27/2022]
Affiliation(s)
- Laura Bennet
- Fetal Physiology and Neuroscience Groups; Department of Physiology; University of Auckland; Auckland New Zealand
| | - Lotte Van Den Heuij
- Fetal Physiology and Neuroscience Groups; Department of Physiology; University of Auckland; Auckland New Zealand
| | - Justin M Dean
- Fetal Physiology and Neuroscience Groups; Department of Physiology; University of Auckland; Auckland New Zealand
| | - Paul Drury
- Fetal Physiology and Neuroscience Groups; Department of Physiology; University of Auckland; Auckland New Zealand
| | - Guido Wassink
- Fetal Physiology and Neuroscience Groups; Department of Physiology; University of Auckland; Auckland New Zealand
| | - Alistair Jan Gunn
- Fetal Physiology and Neuroscience Groups; Department of Physiology; University of Auckland; Auckland New Zealand
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Dean JM, McClendon E, Hansen K, Azimi-Zonooz A, Chen K, Riddle A, Gong X, Sharifnia E, Hagen M, Ahmad T, Leigland LA, Hohimer AR, Kroenke CD, Back SA. Prenatal cerebral ischemia disrupts MRI-defined cortical microstructure through disturbances in neuronal arborization. Sci Transl Med 2013; 5:168ra7. [PMID: 23325800 DOI: 10.1126/scitranslmed.3004669] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Children who survive preterm birth exhibit persistent unexplained disturbances in cerebral cortical growth with associated cognitive and learning disabilities. The mechanisms underlying these deficits remain elusive. We used ex vivo diffusion magnetic resonance imaging to demonstrate in a preterm large-animal model that cerebral ischemia impairs cortical growth and the normal maturational decline in cortical fractional anisotropy (FA). Analysis of pyramidal neurons revealed that cortical deficits were associated with impaired expansion of the dendritic arbor and reduced synaptic density. Together, these findings suggest a link between abnormal cortical FA and disturbances of neuronal morphological development. To experimentally investigate this possibility, we measured the orientation distribution of dendritic branches and observed that it corresponds with the theoretically predicted pattern of increased anisotropy within cases that exhibited elevated cortical FA after ischemia. We conclude that cortical growth impairments are associated with diffuse disturbances in the dendritic arbor and synapse formation of cortical neurons, which may underlie the cognitive and learning disabilities in survivors of preterm birth. Further, measurement of cortical FA may be useful for noninvasively detecting neurological disorders affecting cortical development.
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Affiliation(s)
- Justin M Dean
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Evelyn McClendon
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Kelly Hansen
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Aryan Azimi-Zonooz
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Kevin Chen
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Art Riddle
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Xi Gong
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Elica Sharifnia
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Matthew Hagen
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Tahir Ahmad
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Lindsey A Leigland
- Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR 97239, USA.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA
| | - A Roger Hohimer
- Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Christopher D Kroenke
- Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR 97239, USA.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA
| | - Stephen A Back
- Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA.,Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA
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Dean JM, van de Looij Y, Sizonenko SV, Lodygensky GA, Lazeyras F, Bolouri H, Kjellmer I, Huppi PS, Hagberg H, Mallard C. Delayed cortical impairment following lipopolysaccharide exposure in preterm fetal sheep. Ann Neurol 2011; 70:846-56. [PMID: 22002627 DOI: 10.1002/ana.22480] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 04/28/2011] [Accepted: 05/06/2011] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Preterm infants exhibit chronic deficits in white matter (WM) and cortical maturation. Although fetal infection/inflammation may contribute to WM pathology, the factors contributing to cortical changes are largely unknown. We examined the effect of fetal lipopolysaccharide (LPS) exposure on WM and cortical development as assessed by magnetic resonance imaging (MRI), electroencephalography (EEG), and histopathology in fetal sheep at preterm human equivalent age. METHODS LPS was administered to fetal sheep at 102.5 ± 0.5 days of gestation. Continuous biophysical recordings were analyzed for 10 days after LPS. At postmortem, measurement of cerebral WM and cortical tissue volumes was achieved by stereological techniques. Specific effects of LPS on MRI-assessed T(1)-weighted and T(2)-weighted images, and immunohistochemical expression of oligodendrocytes, proliferating cells, cortical NeuN-positive and Nurr1-positive neurons (subplate marker), and cell death mechanisms were examined. RESULTS We observed reductions in WM (~21%; LPS, 1.19 ± 0.04 vs control, 1.51 ± 0.07 cm(3); p < 0.001) and cortical (~18%; LPS, 2.34 ± 0.10 vs control, 2.85 ± 0.07 cm(3); p < 0.001) volumes, associated with overt and diffuse WM injury, T(1)-/T(2) -weighted signal alterations, and reduced numbers of WM oligodendrocytes (LPS, 485 ± 31 vs control, 699 ± 69 cells/mm(2); p = 0.0189) and NeuN-positive (LPS, 421 ± 71 vs control 718 ± 92 cells/mm(2); p = 0.04) and Nurr1-positive (control, 2.5 ± 0.6 vs LPS, 0.6 ± 0.1 cells/mm(2); p = 0.007) cortical neurons after LPS. Moreover, there was loss of the normal maturational increase in cortical EEG amplitude, which correlated with reduced cortical volumes. INTERPRETATION Fetal exposure to LPS prior to myelination onset can impair both white matter and cortical development in a preclinical large animal model, supporting a role for maternal/fetal infection in the pathogenesis of preterm brain injury.
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Affiliation(s)
- Justin M Dean
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Dean JM, Moravec MD, Grafe M, Abend N, Ren J, Gong X, Volpe JJ, Jensen FE, Hohimer AR, Back SA. Strain-specific differences in perinatal rodent oligodendrocyte lineage progression and its correlation with human. Dev Neurosci 2011; 33:251-60. [PMID: 21865655 DOI: 10.1159/000327242] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 11/04/2010] [Indexed: 01/28/2023] Open
Abstract
Progress in the development of rat models of human periventricular white matter injury (WMI) has been hampered by uncertainty about the developmental window in different rodent strains that coincides with cerebral white matter development in human premature infants. To define strain-specific differences in rat cerebral white matter maturation, we analyzed oligodendrocyte (OL) lineage maturation between postnatal days (P)2 and P14 in three widely studied strains of rat: Sprague-Dawley, Long-Evans and Wistar (W). We previously reported that late OL progenitors (preOL) are the major vulnerable cell type in human periventricular WMI. Strain-specific differences in preOL maturation were found at P2, such that the W rat had the highest percentage and density of preOL relative to the other strains. Overall, at P2, the state of OL maturation was similar to preterm human cerebral white matter. However, by P5, all three strains displayed a similar magnitude and extent of OL maturation that persisted with progressive myelination between P7 and P14. PreOL were the predominant OL lineage stage present in the cerebral cortex through P14, and thus OL lineage maturation occurred latter than in white matter. The hippocampus also displayed a later onset of preOL maturation in all three strains, such that OL lineage maturation and early myelination was not observed to occur until about P14. This timing of preOL maturation in rat cortical gray matter coincided with a similar timing in human cerebral cortex, where preOL also predominated until at least 8 months after full-term birth. These studies support that strain-specific differences in OL lineage immaturity were present in the early perinatal period at about P2, and they define a narrow window of preterm equivalence with human that diminishes by P5. Later developmental onset of preOL maturation in both cerebral cortex and hippocampus coincides with an extended window of potential vulnerability of the OL lineage to hypoxia-ischemia in these gray matter regions.
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Affiliation(s)
- Justin M Dean
- Department of Pediatrics, Oregon Health and Science University, Portland, OR 97239-3098, USA
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Dean JM, Riddle A, Maire J, Hansen KD, Preston M, Barnes AP, Sherman LS, Back SA. An organotypic slice culture model of chronic white matter injury with maturation arrest of oligodendrocyte progenitors. Mol Neurodegener 2011; 6:46. [PMID: 21729326 PMCID: PMC3163199 DOI: 10.1186/1750-1326-6-46] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 07/05/2011] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND CNS myelination disturbances commonly occur in chronic white matter lesions in neurodevelopmental and adult neurological disorders. Recent studies support that myelination failure can involve a disrupted cellular repair mechanism where oligodendrocyte (OL) progenitor cells (OPCs) proliferate in lesions with diffuse astrogliosis, but fail to fully differentiate to mature myelinating OLs. There are no in vitro models that reproduce these features of myelination failure. RESULTS Forebrain coronal slices from postnatal day (P) 0.5/1 rat pups were cultured for 1, 5, or 9 days in vitro (DIV). Slices rapidly exhibited diffuse astrogliosis and accumulation of the extracellular matrix glycosaminoglycan hyaluronan (HA), an inhibitor of OPC differentiation and re-myelination. At 1 DIV ~1.5% of Olig2+ OLs displayed caspase-3 activation, which increased to ~11.5% by 9 DIV. At 1 DIV the density of PDGFRα+ and PDGFRα+/Ki67+ OPCs were significantly elevated compared to 0 DIV (P < 0.01). Despite this proliferative response, at 9 DIV ~60% of white matter OLs were late progenitors (preOLs), compared to ~7% in the postnatal day 10 rat (P < 0.0001), consistent with preOL maturation arrest. Addition of HA to slices significantly decreased the density of MBP+ OLs at 9 DIV compared to controls (217 ± 16 vs. 328 ± 17 cells/mm2, respectively; P = 0.0003), supporting an inhibitory role of HA in OL lineage progression in chronic lesions. CONCLUSIONS Diffuse white matter astrogliosis and early OPC proliferation with impaired OL maturation were reproduced in this model of myelination failure. This system may be used to define mechanisms of OPC maturation arrest and myelination failure related to astrogliosis and HA accumulation.
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Affiliation(s)
- Justin M Dean
- Department of Pediatrics, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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Buser JR, Segovia KN, Dean JM, Nelson K, Beardsley D, Gong X, Luo NL, Ren J, Wan Y, Riddle A, McClure MM, Ji X, Derrick M, Hohimer AR, Back SA, Tan S. Timing of appearance of late oligodendrocyte progenitors coincides with enhanced susceptibility of preterm rabbit cerebral white matter to hypoxia-ischemia. J Cereb Blood Flow Metab 2010; 30:1053-65. [PMID: 20068573 PMCID: PMC2915781 DOI: 10.1038/jcbfm.2009.286] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Emerging evidence supports that premature infants are susceptible to both cerebral white and gray matter injury. In a fetal rabbit model of placental insufficiency, preterm rabbits at embryonic day 22 (E22) exhibited histologic evidence of gray matter injury but minimal white matter injury after global hypoxia-ischemia (H-I). We hypothesized that the dissociation between susceptibility to gray and white matter injury at E22 was related to the timing of appearance of late oligodendrocyte progenitors (preOLs) that are particularly vulnerable in preterm human white matter lesions. During normal rabbit oligodendrocyte (OL) lineage progression, early OL progenitors predominated at E22. PreOL density increased between E24 and E25 in major forebrain white matter tracts. After H-I at E22 and E25, we observed a similar magnitude of cerebral H-I, assessed by cortical microvascular blood flow, and gray matter injury, assessed by caspase activation. However, the increased preOL density at E25 was accompanied by a significant increase in acute white matter injury after H-I that coincided with enhanced preOL degeneration. At E29, significant white matter atrophy developed after H-I at E25 but not E22. Thus, the timing of appearance of preOLs coincided with onset of a developmental window of enhanced white but not gray matter susceptibility to H-I.
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Affiliation(s)
- Joshua R Buser
- Department of Pediatrics, Oregon Health and Science University, Portland, Oregon 97239-3098, USA
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Dean JM, George S, Naylor AS, Mallard C, Gunn AJ, Bennet L. Partial neuroprotection with low-dose infusion of the alpha2-adrenergic receptor agonist clonidine after severe hypoxia in preterm fetal sheep. Neuropharmacology 2008; 55:166-74. [PMID: 18572205 DOI: 10.1016/j.neuropharm.2008.05.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 04/12/2008] [Accepted: 05/07/2008] [Indexed: 10/22/2022]
Abstract
We have previously shown that brief alpha(2)-adrenergic receptor blockade increased neuronal injury after severe hypoxia in preterm fetal sheep. We now examine whether infusion of an alpha(2)-adrenergic receptor agonist, clonidine, is neuroprotective. Preterm fetal sheep (70% gestation) received either saline-vehicle or clonidine at either 10 microg/kg/h (low-dose) or 100 microg/kg/h (high-dose) from 15 min until 4 h after 25 min of umbilical cord occlusion. Both low- and high-dose clonidine infusions after sham-occlusion were associated with transient EEG suppression but no neuronal loss. Low-dose but not high-dose clonidine infusions after umbilical cord occlusion were associated with a significant overall increase in numbers of surviving neurons after three days' recovery. High-dose clonidine was associated with transient hyperglycemia and increased numbers of delayed electrographic seizures. These results provide further evidence that alpha(2)-adrenergic receptor activation shortly after perinatal hypoxia-ischemia can promote neural recovery, but highlight the complex dose-response of exogenous therapy.
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Affiliation(s)
- Justin M Dean
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand
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Bennet L, Booth LC, Ahmed-Nasef N, Dean JM, Davidson J, Quaedackers JS, Gunn AJ. Male disadvantage? Fetal sex and cardiovascular responses to asphyxia in preterm fetal sheep. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1280-6. [PMID: 17596324 DOI: 10.1152/ajpregu.00342.2007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Clinically and experimentally male fetuses are at significantly greater risk of dying or suffering injury at birth, particularly after premature delivery. We undertook a retrospective cohort analysis of 60 female and 65 male singleton preterm fetal sheep (103–104 days, 0.7 gestation) with mean arterial blood pressure (MAP), heart rate, and carotid and femoral blood flow recordings during 25 min of umbilical cord occlusion in utero. Occlusions were stopped early if fetal MAP fell below 8 mmHg or if there was asystole for >20 s. Fetuses that were able to complete the full 25-min period of occlusion showed no differences between sexes for any cardiovascular responses. Similar numbers of occlusions were stopped early in males (mean: 21 min, n = 16) and females (mean: 23 min, n = 16); however, they showed different responses. Short-occlusion males ( n = 16) showed a slower initial fall in femoral vascular conductance, followed by greater bradycardia, hypotension, and associated organ hypoperfusion compared with full-occlusion fetuses. In contrast, short-occlusion females ( n = 16) showed a significantly more rapid early increase in femoral vascular conductance than the full-occlusion fetuses, followed by worsening of bradycardia and hypotension that was intermediate to the full-occlusion fetuses and short-occlusion males. Among all fetuses, MAP at 15 min of occlusion, corresponding with the time of the maximal rate of fall, was correlated with postmortem weight in males ( R2 = 0.07) but not females. In conclusion, male and female fetuses showed remarkably similar chemoreflex and hemodynamic responses to severe asphyxia, but some males did show impaired hemodynamic adaptation within the normal weight range.
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Affiliation(s)
- Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand.
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Wassink G, Bennet L, Booth LC, Jensen EC, Wibbens B, Dean JM, Gunn AJ. The ontogeny of hemodynamic responses to prolonged umbilical cord occlusion in fetal sheep. J Appl Physiol (1985) 2007; 103:1311-7. [PMID: 17656627 DOI: 10.1152/japplphysiol.00396.2007] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is evidence that preterm fetuses have blunted chemoreflex-mediated responses to hypoxia. However, the preterm fetus has much lower aerobic requirements than at term, and so moderate hypoxia may not be sufficient to elicit maximal chemoreflex responses; there are only limited quantitative data on the ontogeny of chemoreflex and hemodynamic responses to severe asphyxia. Chronically instrumented fetal sheep at 0.6 (n = 12), 0.7 (n = 12), and 0.85 (n = 8) of gestational age (GA; term = 147 days) were exposed to 30, 25, or 15 min of complete umbilical cord occlusion, respectively. At all ages, occlusion was associated with early onset of bradycardia, profoundly reduced femoral blood flow and conductance, and hypertension. The 0.6-GA fetuses showed a significantly slower and lesser fall in femoral blood flow and conductance compared with the 0.85-GA group, with a correspondingly reduced relative rise in mean arterial blood pressure. As occlusion continued, the initial adaptation was followed by loss of peripheral vasoconstriction and progressive development of hypotension in all groups. The 0.85-GA fetuses showed significantly more sustained reduction in femoral conductance but also more rapid onset of hypotension than either of the younger groups. Electroencephalographic (EEG) activity was suppressed during occlusion in all groups, but the degree of suppression was less at 0.6 GA than at term. In conclusion, the near-midgestation fetus shows attenuated initial (chemoreflex) peripheral vasomotor responses to severe asphyxia compared with more mature fetuses but more sustained hemodynamic adaptation and reduced suppression of EEG activity during continued occlusion of the umbilical cord.
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Affiliation(s)
- Guido Wassink
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand
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Barrett RD, Bennet L, Davidson J, Dean JM, George S, Emerald BS, Gunn AJ. Destruction and reconstruction: Hypoxia and the developing brain. ACTA ACUST UNITED AC 2007; 81:163-76. [DOI: 10.1002/bdrc.20095] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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George S, Scotter J, Dean JM, Bennet L, Waldvogel HJ, Guan J, Faull RLM, Gunn AJ. Induced cerebral hypothermia reduces post-hypoxic loss of phenotypic striatal neurons in preterm fetal sheep. Exp Neurol 2007; 203:137-47. [PMID: 16962098 DOI: 10.1016/j.expneurol.2006.07.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 07/17/2006] [Accepted: 07/28/2006] [Indexed: 12/20/2022]
Abstract
Perinatal hypoxic-ischemic injury of the basal ganglia is a significant cause of disability in premature infants. Prolonged, moderate cerebral hypothermia has been shown to be neuroprotective after experimental hypoxia-ischemia; however, it has not been tested in the preterm brain. We therefore examined the effects of severe hypoxia and the potential neuroprotective effects of delayed hypothermia on phenotypic striatal neurons. Preterm (0.7 gestation) fetal sheep received complete umbilical cord occlusion for 25 min followed by cerebral hypothermia (fetal extradural temperature reduced from 39.4+/-0.3 degrees C to 29.5+/-2.6 degrees C) from 90 min to 70 h after the end of occlusion. Hypothermia was associated with a significant overall reduction in striatal neuronal loss compared with normothermia-occlusion fetuses (mean+/-SEM, 5.5+/-1.2% vs. 38.1+/-6.5%, P<0.01). Immunohistochemical studies showed that occlusion resulted in a significant loss of calbindin-28 kd, glutamic acid decarboxylase isoform 67 and neuronal nitric oxide synthase-immunopositive neurons (n=7, P<0.05), but not choline acetyltransferase-positive neurons, compared with sham controls (n=7). Hypothermia (n=7) significantly reduced the loss of calbindin-28 kd and neuronal nitric oxide synthase, but not glutamic acid decarboxylase-immunopositive neurons. In conclusion, delayed, prolonged moderate head cooling was associated with selective protection of particular phenotypic striatal projection neurons after severe hypoxia in the preterm fetus. These findings suggest that head cooling may help reduce basal ganglia injury in some premature babies.
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Affiliation(s)
- S George
- Department of Physiology, Faculty of Medicine and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand
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Bennet L, Roelfsema V, Dean JM, Wassink G, Power GG, Jensen EC, Gunn AJ. Regulation of cytochrome oxidase redox state during umbilical cord occlusion in preterm fetal sheep. Am J Physiol Regul Integr Comp Physiol 2006; 292:R1569-76. [PMID: 17170231 DOI: 10.1152/ajpregu.00743.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The preterm fetus is capable of surviving prolonged periods of severe hypoxia without neural injury for much longer than at term. To evaluate the hypothesis that regulated suppression of brain metabolism contributes to this remarkable tolerance, we assessed changes in the redox state of cytochrome oxidase (CytOx) relative to cerebral heat production, and cytotoxic edema measured using cerebral impedance, during 25 min of complete umbilical cord occlusion or sham occlusion in fetal sheep at 0.7 gestation. Occlusion was followed by rapid, profound reduction in relative cerebral oxygenation and EEG intensity and an immediate increase in oxidized CytOx, indicating a reduction in electron flow down the mitochondrial electron transfer chain. Confirming rapid suppression of cerebral metabolism there was a loss of the temperature difference between parietal cortex and body at a time when carotid blood flow was maintained at control values. As occlusion continued, severe hypotension/hypoperfusion developed, with a further increase in CytOx levels to a plateau between 8 and 13 min and a progressive rise in cerebral impedance. In conclusion, these data strongly suggest active regulation of cerebral metabolism during the initial response to severe hypoxia, which may help to protect the immature brain from injury.
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Affiliation(s)
- Laura Bennet
- Department of Physiology, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
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Bennet L, Roelfsema V, George S, Dean JM, Emerald BS, Gunn AJ. The effect of cerebral hypothermia on white and grey matter injury induced by severe hypoxia in preterm fetal sheep. J Physiol 2006; 578:491-506. [PMID: 17095565 PMCID: PMC2075155 DOI: 10.1113/jphysiol.2006.119602] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Prolonged, moderate cerebral hypothermia is consistently neuroprotective after experimental hypoxia-ischaemia; however, it has not been tested in the preterm brain. Preterm (0.7 gestation) fetal sheep received complete umbilical cord occlusion for 25 min followed by cerebral hypothermia (fetal extradural temperature reduced from 39.4 +/- 0.3 to 29.5 +/- 2.6 degrees C) from 90 min to 70 h after the end of occlusion or sham cooling. Occlusion led to severe acidosis and profound hypotension, which recovered rapidly after release of occlusion. After 3 days recovery the EEG spectral frequency, but not total intensity, was increased in the hypothermia-occlusion group compared with normothermia-occlusion. Hypothermia was associated with a significant overall reduction in loss of immature oligodendrocytes in the periventricular white matter (P < 0.001), and neuronal loss in the hippocampus and basal ganglia (P < 0.001), with suppression of activated caspase-3 and microglia (isolectin-B4 positive). Proliferation was significantly reduced in periventricular white matter after occlusion (P < 0.05), but not improved after hypothermia. In conclusion, delayed, prolonged head cooling after a profound hypoxic insult in the preterm fetus was associated with a significant reduction in loss of neurons and immature oligodendroglia, with evidence of EEG and haemodynamic improvement after 3 days recovery, but also with a persisting reduction in proliferation of cells in the periventricular region. Further studies are required to evaluate the long-term impact of cooling on brain growth and maturation.
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Affiliation(s)
- L Bennet
- Department of Physiology and Paediatrics, University of Auckland, Auckland, New Zealand
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