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Zhou KQ, Davidson JO, Gunn AJ. Does sex materially modulate responses to therapeutic hypothermia? Pediatr Res 2023; 94:1259-1260. [PMID: 37185964 PMCID: PMC10589080 DOI: 10.1038/s41390-023-02624-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 04/07/2023] [Indexed: 05/17/2023]
Affiliation(s)
- Kelly Q Zhou
- The Department of Physiology, The University of Auckland, Auckland, 1023, New Zealand
| | - Joanne O Davidson
- The Department of Physiology, The University of Auckland, Auckland, 1023, New Zealand
| | - Alistair J Gunn
- The Department of Physiology, The University of Auckland, Auckland, 1023, New Zealand.
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King VJ, Bennet L, Stone PR, Clark A, Gunn AJ, Dhillon SK. Fetal growth restriction and stillbirth: Biomarkers for identifying at risk fetuses. Front Physiol 2022; 13:959750. [PMID: 36060697 PMCID: PMC9437293 DOI: 10.3389/fphys.2022.959750] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/29/2022] [Indexed: 11/13/2022] Open
Abstract
Fetal growth restriction (FGR) is a major cause of stillbirth, prematurity and impaired neurodevelopment. Its etiology is multifactorial, but many cases are related to impaired placental development and dysfunction, with reduced nutrient and oxygen supply. The fetus has a remarkable ability to respond to hypoxic challenges and mounts protective adaptations to match growth to reduced nutrient availability. However, with progressive placental dysfunction, chronic hypoxia may progress to a level where fetus can no longer adapt, or there may be superimposed acute hypoxic events. Improving detection and effective monitoring of progression is critical for the management of complicated pregnancies to balance the risk of worsening fetal oxygen deprivation in utero, against the consequences of iatrogenic preterm birth. Current surveillance modalities include frequent fetal Doppler ultrasound, and fetal heart rate monitoring. However, nearly half of FGR cases are not detected in utero, and conventional surveillance does not prevent a high proportion of stillbirths. We review diagnostic challenges and limitations in current screening and monitoring practices and discuss potential ways to better identify FGR, and, critically, to identify the “tipping point” when a chronically hypoxic fetus is at risk of progressive acidosis and stillbirth.
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Affiliation(s)
- Victoria J. King
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Peter R. Stone
- Department of Obstetrics and Gynaecology, The University of Auckland, Auckland, New Zealand
| | - Alys Clark
- Department of Obstetrics and Gynaecology, The University of Auckland, Auckland, New Zealand
- Auckland Biomedical Engineering Institute, The University of Auckland, Auckland, New Zealand
| | - Alistair J. Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Simerdeep K. Dhillon
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
- *Correspondence: Simerdeep K. Dhillon,
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3
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Murata T, Kyozuka H, Yasuda S, Fukuda T, Tanaka T, Fujimori K. Effects of maternal ritodrine hydrochloride administration on the heart rate of preterm fetal sheep with intraamniotic inflammation. PLoS One 2022; 17:e0265872. [PMID: 35358222 PMCID: PMC8970407 DOI: 10.1371/journal.pone.0265872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 03/04/2022] [Indexed: 11/18/2022] Open
Abstract
Ritodrine hydrochloride is used for pregnancy prolongation and intrauterine fetal resuscitation. However, its clinical significance in intraamniotic inflammation during preterm labor and intrauterine fetal distress is unclear. We investigated the effects of maternal ritodrine hydrochloride administration (MRA; 200 μg/min for 2 h, followed by 800 μg/min for 2 h after 24 h) on fetal physiological parameters. For this purpose, we used chronically instrumented pregnant sheep at 113–119 d (term = 145 d) of gestation without (Group 1, n = 5) and with (Group 2, n = 5) intraamniotic inflammation induced by lipopolysaccharide injection into the amniotic cavity. The changes in fetal heart rate (FHR) and short-term variability (STV) and long-term variability (LTV) in FHR, fetal blood pressure, and fetal arterial blood gas (FABG) values were measured before and at 1 and 2 h after initiating MRA. Before MRA, all parameters were similar between Groups 1 and 2; however, there was significantly higher STV in Group 2 than in Group 1 before MRA at 800 μg/min, significantly higher partial arterial pressure of carbon dioxide in FABG in Group 2 than in Group 1 before MRA at 200 μg/min, and significantly lower blood glucose (BG) in Group 2 than in Group 1 before MRA at 800 μg/min. One hour after MRA, the FHR, STV, and LTV were significantly higher at 800 μg/min than those at the baseline in Group 1, as determined by the Friedman test; however, no significant difference was observed in Group 2. Additionally, the FABG pH significantly decreased 1 h after MRA at 800 μg/min in Group 2, whereas FABG lactate and BG significantly increased 2 h after MRA at 800 μg/min in Groups 1 and 2. Thus, short-term MRA at 800 μg/min increased the FHR, STV, and LTV significantly; these values were further modified under intraamniotic inflammation.
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Affiliation(s)
- Tsuyoshi Murata
- Department of Obstetrics and Gynecology, Fukushima Medical University School of Medicine, Fukushima, Japan
- * E-mail:
| | - Hyo Kyozuka
- Department of Obstetrics and Gynecology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Shun Yasuda
- Department of Obstetrics and Gynecology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Toma Fukuda
- Department of Obstetrics and Gynecology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Teruyoshi Tanaka
- Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Keiya Fujimori
- Department of Obstetrics and Gynecology, Fukushima Medical University School of Medicine, Fukushima, Japan
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4
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Umbilical cord blood therapy modulates neonatal hypoxic ischemic brain injury in both females and males. Sci Rep 2021; 11:15788. [PMID: 34349144 PMCID: PMC8338979 DOI: 10.1038/s41598-021-95035-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/20/2021] [Indexed: 12/12/2022] Open
Abstract
Preclinical and clinical studies have shown that sex is a significant risk factor for perinatal morbidity and mortality, with males being more susceptible to neonatal hypoxic ischemic (HI) brain injury. No study has investigated sexual dimorphism in the efficacy of umbilical cord blood (UCB) cell therapy. HI injury was induced in postnatal day 10 (PND10) rat pups using the Rice-Vannucci method of carotid artery ligation. Pups received 3 doses of UCB cells (PND11, 13, 20) and underwent behavioural testing. On PND50, brains were collected for immunohistochemical analysis. Behavioural and neuropathological outcomes were assessed for sex differences. HI brain injury resulted in a significant decrease in brain weight and increase in tissue loss in females and males. Females and males also exhibited significant cell death, region-specific neuron loss and long-term behavioural deficits. Females had significantly smaller brains overall compared to males and males had significantly reduced neuron numbers in the cortex compared to females. UCB administration improved multiple aspects of neuropathology and functional outcomes in males and females. Females and males both exhibited injury following HI. This is the first preclinical evidence that UCB is an appropriate treatment for neonatal brain injury in both female and male neonates.
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5
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Nippita S, Carranza ASO, Paul ME. Funic potassium chloride injection during intact dilation and evacuation. Contraception 2021; 104:275-277. [PMID: 33831443 DOI: 10.1016/j.contraception.2021.03.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/26/2021] [Accepted: 03/30/2021] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To describe effectiveness of funic potassium chloride (KCl) injection for fetal demise during intact dilation and evacuation (D&E). STUDY DESIGN We abstracted medical records of patients who underwent standard or intact D&E to identify those who had intact D&E from 20 weeks 0 days through 23 weeks 6 days from February 2016 to August 2017 at one academic center. We extracted data on time to asystole following KCl injection, as well as incidents including hemorrhage, infection, uterine perforation, and unplanned admissions for up to 6 months following each procedure. RESULTS Of 57 procedures, 32 (56%) were intact. Median time from KCl injection to fetal asystole was 48 seconds (interquartile range [IQR] 34-100). Median time to asystole at weeks 20 and 21 (46 seconds [IQR 34-60 seconds]) did not differ significantly from weeks 22 and 23 (85 seconds [IQR 34-200 seconds]), p = 0.15. Asystole occurred in less than four minutes in all cases but one. No adverse events occurred with either the funic KCl injections or the intact D&E procedures. CONCLUSION Funic KCl injection for intact D&E usually causes fetal asystole in less than 4 minutes. IMPLICATIONS Funic KCl injection under direct visualization is a feasible method to induce fetal asystole at the time of intact dilation and evacuation.
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Affiliation(s)
- Siripanth Nippita
- Department of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center, Boston, MA, United States; Department of Obstetrics, Gynecology, and Reproductive Biology, Harvard Medical School, Boston, MA, United States
| | | | - Maureen E Paul
- Department of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center, Boston, MA, United States; Department of Obstetrics, Gynecology, and Reproductive Biology, Harvard Medical School, Boston, MA, United States
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6
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Rodriguez J, Li T, Xu Y, Sun Y, Zhu C. Role of apoptosis-inducing factor in perinatal hypoxic-ischemic brain injury. Neural Regen Res 2021; 16:205-213. [PMID: 32859765 PMCID: PMC7896227 DOI: 10.4103/1673-5374.290875] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Perinatal complications, such as asphyxia, can cause brain injuries that are often associated with subsequent neurological deficits, such as cerebral palsy or mental retardation. The mechanisms of perinatal brain injury are not fully understood, but mitochondria play a prominent role not only due to their central function in metabolism but also because many proteins with apoptosis-related functions are located in the mitochondrion. Among these proteins, apoptosis-inducing factor has already been shown to be an important factor involved in neuronal cell death upon hypoxia-ischemia, but a better understanding of the mechanisms behind these processes is required for the development of more effective treatments during the early stages of perinatal brain injury. In this review, we focus on the molecular mechanisms of hypoxic-ischemic encephalopathy, specifically on the importance of apoptosis-inducing factor. The relevance of apoptosis-inducing factor is based not only because it participates in the caspase-independent apoptotic pathway but also because it plays a crucial role in mitochondrial energetic functionality, especially with regard to the maintenance of electron transport during oxidative phosphorylation and in oxidative stress, acting as a free radical scavenger. We also discuss all the different apoptosis-inducing factor isoforms discovered, focusing especially on apoptosis-inducing factor 2, which is only expressed in the brain and the functions of which are starting now to be clarified. Finally, we summarized the interaction of apoptosis-inducing factor with several proteins that are crucial for both apoptosis-inducing factor functions (pro-survival and pro-apoptotic) and that are highly important in order to develop promising therapeutic targets for improving outcomes after perinatal brain injury.
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Affiliation(s)
- Juan Rodriguez
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Tao Li
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Henan Key Laboratory of Child Brain Injury, Institute of Neuroscience and Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - Yiran Xu
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Henan Key Laboratory of Child Brain Injury, Institute of Neuroscience and Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - Yanyan Sun
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Anatomy, School of Basic Medical Science, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Changlian Zhu
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Henan Key Laboratory of Child Brain Injury, Institute of Neuroscience and Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China; Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
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7
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Davidson JO, van den Heuij LG, Fraser M, Wassink G, Miller SL, Lim R, Wallace EM, Jenkin G, Gunn AJ, Bennet L. Window of opportunity for human amnion epithelial stem cells to attenuate astrogliosis after umbilical cord occlusion in preterm fetal sheep. Stem Cells Transl Med 2020; 10:427-440. [PMID: 33103374 PMCID: PMC7900589 DOI: 10.1002/sctm.20-0314] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/22/2020] [Accepted: 10/09/2020] [Indexed: 12/19/2022] Open
Abstract
There is increasing evidence that administration of many types of stem cells, including human amnion epithelial cells (hAECs), can reduce hypoxic-ischemic injury, including in the perinatal brain. However, the therapeutic window for single dose treatment is not known. We compared the effects of early and delayed intracerebroventricular administration of hAECs in fetal sheep at 0.7 gestation on brain injury induced by 25 minutes of complete umbilical cord occlusion (UCO) or sham occlusion. Fetuses received either 1 × 106 hAECs or vehicle alone, as an infusion over 1 hour, either 2 or 24 hours after UCO. Fetuses were killed for brain histology at 7 days post-UCO. hAEC infusion at both 2 and 24 hours had dramatic anti-inflammatory and anti-gliotic effects, including significantly attenuating the increase in microglia after UCO in the white and gray matter and the number of astrocytes in the white matter. Both protocols partially improved myelination, but had no effect on total or immature/mature numbers of oligodendrocytes. Neuronal survival in the hippocampus was increased by hAEC infusion at either 2 or 24 hours, whereas only hAECs at 24 hours were associated with improved neuronal survival in the striatum and thalamus. Neither protocol improved recovery of electroencephalographic (EEG) power. These data suggest that a single infusion of hAECs is anti-inflammatory, anti-gliotic, and neuroprotective in preterm fetal sheep when given up to 24 hours after hypoxia-ischemia, but was associated with limited white matter protection after 7 days recovery and no improvement in the recovery of EEG power.
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Affiliation(s)
- Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Lotte G van den Heuij
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Mhoyra Fraser
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Rebecca Lim
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Euan M Wallace
- 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
| | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
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8
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Babiszewska M. Effects of energy and essential fatty acids content in breast milk on infant's head dimensions. Am J Hum Biol 2020; 32:e23418. [PMID: 32307819 DOI: 10.1002/ajhb.23418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/01/2020] [Accepted: 03/19/2020] [Indexed: 11/07/2022] Open
Abstract
OBJECTIVES Essential fatty acids (EFA), including linoleic acid (LA) and alpha-linolenic acid (ALA), are indispensable for proper brain growth especially in the first months after birth when it develops most rapidly. Since fats, especially EFA, in breast milk are highly variable between mothers, we indirectly examined whether milk energy, LA and ALA content in breast milk affect volume and shape of the infant's head. METHODS The study encompassed 60 mothers and their healthy term-born infants between the third and sixth month of lactation. The percentage of macronutrients and dry matter in human milk samples was assessed using Fourier-transform infrared spectroscopy (FTIR), and LA and ALA concentrations in breast milk were determined using gas chromatography (GC). Infant head measurements were taken using standard anthropometric equipment and methods. RESULTS LA content in breast milk was found to be positively associated with head volume in boys. Furthermore, ALA content was positively associated with the head height-to-length ratio thus with more arched head in infants irrespective of sex. No relationship was found between milk energy content in mothers' milk and infant head dimensions. CONCLUSIONS This is the first study to demonstrate a relationship between EFA concentration in human milk and infant head dimensions. Given that LA and ALA in human milk are variable in women and due to the extremely rapid growth of nerve tissue in the first months of life, adequate supply of EFA in breast milk should attract the attention of public health sciences.
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Affiliation(s)
- Magdalena Babiszewska
- Department of Anthropology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
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9
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Kasai M, Lear CA, Davidson JO, Beacom MJ, Drury PP, Maeda Y, Miyagi E, Ikeda T, Bennet L, Gunn AJ. Early sinusoidal heart rate patterns and heart rate variability to assess hypoxia-ischaemia in near-term fetal sheep. J Physiol 2019; 597:5535-5548. [PMID: 31529698 DOI: 10.1113/jp278523] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 08/26/2019] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS •Therapeutic hypothermia needs to be started as early as possible in the first 6 h after acute injury caused by hypoxia-ischaemia (HI), but the severity and timing of HI are often unclear. In this study we evaluated whether measures of heart rate variability (HRV) might provide early biomarkers of HI. •The duration but not magnitude of suppression of HRV power and conversely increased sample entropy of the heart rate were associated with severity of HI, such that changes in the first 3 h did not discriminate between groups. •Relative changes in HRV power bands showed different patterns between groups and therefore may have the potential to evaluate the severity of HI. •Aberrant fetal heart rate patterns and increased arginine vasopressin levels in the first hour after moderate and severe HI were correlated with loss of EEG power after 3 days' recovery, suggesting potential utility as early biomarkers of outcome. ABSTRACT Therapeutic hypothermia is partially neuroprotective after acute injury caused by hypoxia-ischaemia (HI), likely because the timing and severity of HI are often unclear, making timely recruitment for treatment challenging. We evaluated the utility of changes in heart rate variability (HRV) after HI as biomarkers of the timing and severity of acute HI. Chronically instrumented fetal sheep at 0.85 gestational age were exposed to different durations of umbilical cord occlusion to produce mild (n = 6), moderate (n = 8) or severe HI (n = 8) or to sham occlusion (n = 5). Heart rate (HR) and HRV indices were assessed until 72 h after HI. All HI groups showed suppressed very low frequency HRV power and elevated sample entropy for the first 3 h; more prolonged changes were associated with greater severity of HI. Analysis of relative changes in spectral power showed that the moderate and severe groups showed a shift towards higher HRV frequencies, which was most marked after severe HI. This shift was associated with abnormal rhythmic HR patterns including sinusoidal patterns in the first hour after HI, and with elevated plasma levels of arginine vasopressin, which were correlated with subsequent loss of EEG power by day 3. In conclusion, absolute changes in HRV power in the first 3 h after acute HI were not significantly related to the severity of HI. The intriguing relative shift in spectral power towards higher frequencies likely reflects greater autonomic dysfunction after severe HI. However, sinusoidal HR patterns and elevated vasopressin levels may have utility as biomarkers of severe HI.
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Affiliation(s)
- Michi Kasai
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand.,Department of Obstetrics and Gynecology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Christopher A Lear
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand
| | - Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand
| | - Michael J Beacom
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand
| | - Paul P Drury
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand
| | - Yoshiki Maeda
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand.,Department of Obstetrics and Gynecology, Mie University, Mie, Japan
| | - Etsuko Miyagi
- Department of Obstetrics and Gynecology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Tomoaki Ikeda
- Department of Obstetrics and Gynecology, Mie University, Mie, Japan
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand
| | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, New Zealand
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10
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Morrison JL, Berry MJ, Botting KJ, Darby JRT, Frasch MG, Gatford KL, Giussani DA, Gray CL, Harding R, Herrera EA, Kemp MW, Lock MC, McMillen IC, Moss TJ, Musk GC, Oliver MH, Regnault TRH, Roberts CT, Soo JY, Tellam RL. Improving pregnancy outcomes in humans through studies in sheep. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1123-R1153. [PMID: 30325659 DOI: 10.1152/ajpregu.00391.2017] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Experimental studies that are relevant to human pregnancy rely on the selection of appropriate animal models as an important element in experimental design. Consideration of the strengths and weaknesses of any animal model of human disease is fundamental to effective and meaningful translation of preclinical research. Studies in sheep have made significant contributions to our understanding of the normal and abnormal development of the fetus. As a model of human pregnancy, studies in sheep have enabled scientists and clinicians to answer questions about the etiology and treatment of poor maternal, placental, and fetal health and to provide an evidence base for translation of interventions to the clinic. The aim of this review is to highlight the advances in perinatal human medicine that have been achieved following translation of research using the pregnant sheep and fetus.
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Affiliation(s)
- Janna L Morrison
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Mary J Berry
- Department of Paediatrics and Child Health, University of Otago , Wellington , New Zealand
| | - Kimberley J Botting
- Department of Physiology, Development, and Neuroscience, University of Cambridge , Cambridge , United Kingdom
| | - Jack R T Darby
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Martin G Frasch
- Department of Obstetrics and Gynecology, University of Washington , Seattle, Washington
| | - Kathryn L Gatford
- Robinson Research Institute and Adelaide Medical School, University of Adelaide , Adelaide, South Australia , Australia
| | - Dino A Giussani
- Department of Physiology, Development, and Neuroscience, University of Cambridge , Cambridge , United Kingdom
| | - Clint L Gray
- Department of Paediatrics and Child Health, University of Otago , Wellington , New Zealand
| | - Richard Harding
- Department of Anatomy and Developmental Biology, Monash University , Clayton, Victoria , Australia
| | - Emilio A Herrera
- Pathophysiology Program, Biomedical Sciences Institute (ICBM), Faculty of Medicine, University of Chile , Santiago , Chile
| | - Matthew W Kemp
- Division of Obstetrics and Gynecology, University of Western Australia , Perth, Western Australia , Australia
| | - Mitchell C Lock
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - I Caroline McMillen
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Timothy J Moss
- The Ritchie Centre, Hudson Institute of Medical Research, Department of Obstetrics and Gynaecology, Monash University , Clayton, Victoria , Australia
| | - Gabrielle C Musk
- Animal Care Services, University of Western Australia , Perth, Western Australia , Australia
| | - Mark H Oliver
- Liggins Institute, University of Auckland , Auckland , New Zealand
| | - Timothy R H Regnault
- Department of Obstetrics and Gynecology and Department of Physiology and Pharmacology, Western University, and Children's Health Research Institute , London, Ontario , Canada
| | - Claire T Roberts
- Robinson Research Institute and Adelaide Medical School, University of Adelaide , Adelaide, South Australia , Australia
| | - Jia Yin Soo
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Ross L Tellam
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
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11
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Song Y, Dahl M, Leavitt W, Alvord J, Bradford CY, Albertine KH, Pillow JJ. Vitamin A Protects the Preterm Lamb Diaphragm Against Adverse Effects of Mechanical Ventilation. Front Physiol 2018; 9:1119. [PMID: 30150942 PMCID: PMC6099107 DOI: 10.3389/fphys.2018.01119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/25/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Preterm infants are deficient in vitamin A, which is essential for growth and development of the diaphragm. Preterm infants often require mechanical ventilation (MV) for respiratory distress. In adults, MV is associated with the development of ventilation-induced diaphragm dysfunction and difficulty weaning from the ventilator. We assessed the impact of MV on the preterm diaphragm and the protective effect of vitamin A during MV. Methods: Preterm lambs delivered operatively at ∼131 days gestation (full gestation: 150 days) received respiratory support by synchronized intermittent mandatory ventilation for 3 days. Lambs in the treated group received daily (24 h) enteral doses of 2500 IU/kg/day vitamin A combined with 250 IU/kg/day retinoic acid (VARA) during MV, while MV control lambs received saline. Unventilated fetal reference lambs were euthanized at birth, without being allowed to breathe. The fetal diaphragm was collected to quantify mRNA levels of myosin heavy chain (MHC) isoforms, atrophy genes, antioxidant genes, and pro-inflammatory genes; to determine ubiquitin proteasome pathway activity; to measure the abundance of protein carbonyl, and to investigate metabolic signaling. Results: Postnatal MV significantly decreased expression level of the neonatal MHC gene but increased expression level of MHC IIx mRNA level (p < 0.05). Proteasome activity increased after 3 days MV, accompanied by increased MuRF1 mRNA level and accumulated protein carbonyl abundance. VARA supplementation decreased proteasome activity and FOXO1 signaling, down-regulated MuRF1 expression, and reduced reactive oxidant production. Conclusion: These findings suggest that 3 days of MV results in abnormal myofibrillar composition, activation of the proteolytic pathway, and oxidative injury of diaphragms in mechanically ventilated preterm lambs. Daily enteral VARA protects the preterm diaphragm from these adverse effects.
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Affiliation(s)
- Yong Song
- School of Human Sciences, The University of Western Australia, Crawley, WA, Australia.,Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Crawley, WA, Australia.,School of Public Health, Curtin University, Bentley, WA, Australia.,Centre for Genetic Origins of Health and Disease, The University of Western Australia, Curtin University, Crawley, WA, Australia
| | - MarJanna Dahl
- Department of Pediatrics, University of Utah, Salt Lake City, UT, United States
| | - Wendy Leavitt
- Department of Pediatrics, University of Utah, Salt Lake City, UT, United States
| | - Jeremy Alvord
- Department of Pediatrics, University of Utah, Salt Lake City, UT, United States
| | - Calan Y Bradford
- Department of Pediatrics, University of Utah, Salt Lake City, UT, United States
| | - Kurt H Albertine
- Department of Pediatrics, University of Utah, Salt Lake City, UT, United States
| | - J Jane Pillow
- School of Human Sciences, The University of Western Australia, Crawley, WA, Australia.,Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Crawley, WA, Australia
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12
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Galinsky R, Dhillon SK, Lear CA, Yamaguchi K, Wassink G, Gunn AJ, Bennet L. Magnesium sulfate and sex differences in cardiovascular and neural adaptations during normoxia and asphyxia in preterm fetal sheep. Am J Physiol Regul Integr Comp Physiol 2018; 315:R205-R217. [PMID: 29561649 DOI: 10.1152/ajpregu.00390.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Magnesium sulfate (MgSO4) is recommended for preterm neuroprotection, preeclampsia, and preterm labor prophylaxis. There is an important, unmet need to carefully test clinical interventions in both sexes. Therefore, we aimed to investigate cardiovascular and neurophysiological adaptations to MgSO4 during normoxia and asphyxia in preterm male and female fetal sheep. Fetuses were instrumented at 98 ± 1 days of gestation (term = 147 days). At 104 days, unanesthetized fetuses were randomly assigned to intravenous MgSO4 ( n = 12 female, 10 male) or saline ( n = 13 female, 10 male). At 105 days fetuses underwent umbilical cord occlusion for up to 25 min. Occlusions were stopped early if mean arterial blood pressure (MAP) fell below 8 mmHg or asystole occurred for >20 s. During normoxia, MgSO4 was associated with similar reductions in fetal heart rate (FHR), EEG power, and movement in both sexes ( P < 0.05 vs. saline controls) and suppression of α- and β-spectral band power in males ( P < 0.05 vs. saline controls). During occlusion, similar FHR and MAP responses occurred in MgSO4-treated males and females compared with saline controls. Recovery of FHR and MAP after release of occlusion was more prolonged in MgSO4-treated males ( P < 0.05 vs. saline controls). During and after occlusion, EEG power was lower in MgSO4-treated females ( P < 0.05 vs. saline controls). In conclusion, MgSO4 infusion was associated with subtle sex-specific effects on EEG spectral power and cardiac responses to asphyxia in utero, possibly reflecting sex-specific differences in interneuronal connectivity and regulation of cardiac output.
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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 , Clayton, VIC , Australia
| | | | - Christopher A Lear
- Department of Physiology, University of Auckland , Auckland , New Zealand
| | - Kyohei Yamaguchi
- Department of Physiology, University of Auckland , Auckland , New Zealand
| | - Guido Wassink
- 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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13
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Le B, Sutherland MR, Black MJ. Maladaptive structural remodelling of the heart following preterm birth. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2017.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Duan AQ, Darby JRT, Soo JY, Lock MC, Zhu MY, Flynn LV, Perumal SR, Macgowan CK, Selvanayagam JB, Morrison JL, Seed M. Feasibility of phase-contrast cine magnetic resonance imaging for measuring blood flow in the sheep fetus. Am J Physiol Regul Integr Comp Physiol 2017; 317:R780-R792. [PMID: 29351431 DOI: 10.1152/ajpregu.00273.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Phase-contrast cine MRI (PC-MRI) is the gold-standard noninvasive technique for measuring vessel blood flow and has previously been applied in the human fetal circulation. We aimed to assess the feasibility of using PC-MRI to define the distribution of the fetal circulation in sheep. Fetuses were catheterized at 119-120 days of gestation (term, 150 days) and underwent MRI at ∼123 days of gestation under isoflurane anesthesia, ventilated at a FIO2 of 1.0. PC-MRI was performed using a fetal arterial blood pressure catheter signal for cardiac triggering. Blood flows were measured in the major fetal vessels, including the main pulmonary artery, ascending and descending aorta, superior vena cava, ductus arteriosus, left and right pulmonary arteries, umbilical vein, ductus venosus, and common carotid artery and were indexed to estimated fetal weight. The combined ventricular output, pulmonary blood flow, and flow across the foramen ovale were calculated from vessel flows. Intraobserver and interobserver agreement and reproducibility was assessed. Blood flow measurements were successfully obtained in 61 out of 74 vessels (82.4%) interrogated in 9 fetuses. There was good intraobserver [R = 0.998, P < 0.0001; intraclass correlation (ICC) = 0.997] and interobserver agreement (R = 0.996, P < 0.0001; ICC = 0.996). Repeated MRI measurements showed good reproducibility (R = 0.989, P = 0.0002; ICC = 0.990). We conclude that PC-MRI using fetal catheters for gating triggers is feasible in the major vessels of late gestation fetal sheep. This approach may provide a useful new tool for assessing the circulatory characteristics of fetal sheep models of human disease, including fetal growth restriction and congenital heart disease.
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Affiliation(s)
- An Qi Duan
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jack R T Darby
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Jia Yin Soo
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Mitchell C Lock
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Meng Yuan Zhu
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Lucy V Flynn
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Sunthara Rajan Perumal
- Preclinical, Imaging, and Research Laboratories, South Australian Health and Medical Research Institute, Gilles Plains, Adelaide, Australia
| | - Christopher K Macgowan
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Division of Translational Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
| | | | - Janna L Morrison
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Mike Seed
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada
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15
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Bennet L. Sex, drugs and rock and roll: tales from preterm fetal life. J Physiol 2017; 595:1865-1881. [PMID: 28094441 DOI: 10.1113/jp272999] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Accepted: 12/22/2016] [Indexed: 12/14/2022] Open
Abstract
Premature fetuses and babies are at greater risk of mortality and morbidity than their term counterparts. The underlying causes are multifactorial, but include exposure to hypoxia. Immaturity of organs and their functional control may impair the physiological defence responses to hypoxia and the preterm fetal responses, or lack thereof, to moderate hypoxia appear to support this concept. However, as this review demonstrates, despite immaturity, the preterm fetus responds to asphyxia in a qualitatively similar manner to that seen at term. This highlights the importance in understanding metabolism versus homeostatic threat when assessing fetal responses to adverse challenges such as hypoxia. Data are presented to show that the preterm fetal adaptation to asphyxia is triphasic in nature. Phase one represents the rapid institution of maximal defences, designed to maintain blood pressure and central perfusion at the expense of peripheral organs. Phase two is one of adaptive compensation. Controlled reperfusion partially offsets peripheral tissue oxygen debt, while maintaining sufficient vasoconstriction to limit the fall in perfusion. Phase three is about decompensation. Strikingly, the preterm fetus generally performs better during phases two and three, and can survive for longer without injury. Paradoxically, however, the ability to survive can lead to longer exposure to hypotension and hypoperfusion and thus potentially greater injury. The effects of fetal sex, inflammation and drugs on the triphasic adaptations are reviewed. Finally, the review highlights the need for more comprehensive studies to understand the complexity of perinatal physiology if we are to develop effective strategies to improve preterm outcomes.
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Affiliation(s)
- Laura Bennet
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, 1023, New Zealand
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16
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van den Heuij LG, Wassink G, Gunn AJ, Bennet L. Using Pregnant Sheep to Model Developmental Brain Damage. NEUROMETHODS 2016. [DOI: 10.1007/978-1-4939-3014-2_16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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17
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Eiby YA, Lumbers ER, Staunton MP, Wright LL, Colditz PB, Wright IMR, Lingwood BE. Endogenous angiotensins and catecholamines do not reduce skin blood flow or prevent hypotension in preterm piglets. Physiol Rep 2014; 2:2/12/e12245. [PMID: 25538149 PMCID: PMC4332223 DOI: 10.14814/phy2.12245] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Endocrine control of cardiovascular function is probably immature in the preterm infant; thus, it may contribute to the relative ineffectiveness of current adrenergic treatments for preterm cardiovascular compromise. This study aimed to determine the cardiovascular and hormonal responses to stress in the preterm piglet. Piglets were delivered by cesarean section either preterm (97 of 115 days) or at term (113 days). An additional group of preterm piglets received maternal glucocorticoids as used clinically. Piglets were sedated and underwent hypoxia (4% FiO2 for 20 min) to stimulate a cardiovascular response. Arterial blood pressure, skin blood flow, heart rate and plasma levels of epinephrine, norepinephrine, angiotensin II (Ang II), angiotensin‐(1–7) (Ang‐(1‐7)), and cortisol were measured. Term piglets responded to hypoxia with vasoconstriction; preterm piglets had a lesser response. Preterm piglets had lower blood pressures throughout, with a delayed blood pressure response to the hypoxic stress compared with term piglets. This immature response occurred despite similar high levels of circulating catecholamines, and higher levels of Ang II compared with term animals. Prenatal exposure to glucocorticoids increased the ratio of Ang‐(1‐7):Ang II. Preterm piglets, in contrast to term piglets, had no increase in cortisol levels in response to hypoxia. Preterm piglets have immature physiological responses to a hypoxic stress but no deficit of circulating catecholamines. Reduced vasoconstriction in preterm piglets could result from vasodilator actions of Ang II. In glucocorticoid exposed preterm piglets, further inhibition of vasoconstriction may occur because of an increased conversion of Ang II to Ang‐(1‐7). This study aimed to determine if immature hormonal control of the cardiovascular system contributes to preterm cardiovascular compromise. Physiological and hormonal responses of preterm piglets to hypoxia are immature compared with term piglets. This is not due to a lack of endogenous catecholamines or angiotensin II, but may be due to the differences in cardiovascular actions of the renin–angiotensin system.
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Affiliation(s)
- Yvonne A Eiby
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Eugenie R Lumbers
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Michael P Staunton
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Layne L Wright
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Paul B Colditz
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Ian M R Wright
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia Graduate School of Medicine and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
| | - Barbara E Lingwood
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia
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18
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Galinsky R, Jensen EC, Bennet L, Mitchell CJ, Gunn ER, Wassink G, Fraser M, Westgate JA, Gunn AJ. Sustained sympathetic nervous system support of arterial blood pressure during repeated brief umbilical cord occlusions in near-term fetal sheep. Am J Physiol Regul Integr Comp Physiol 2014; 306:R787-95. [PMID: 24647590 DOI: 10.1152/ajpregu.00001.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic nervous system (SNS)-mediated peripheral vasoconstriction plays a key role in initial maintenance of blood pressure during rapid-onset asphyxia in the mammalian fetus, but it is attenuated after the first few minutes. It is unclear whether the SNS response is sustained during the brief, but frequently repeated, episodes of asphyxia characteristic of labor. In the present study, 14 fetal sheep at 0.85 of gestation received either chemical sympathectomy with 6-hydroxydopamine (6-OHDA; n = 7) or sham injection (control; n = 7), followed 4-5 days later by repeated 2-min episodes of complete umbilical cord occlusion every 5 min for up to 4 h or until mean arterial blood pressure (MAP) fell to <20 mmHg for two successive occlusions. In controls, umbilical cord occlusions were associated with a rapid initial fall in fetal heart rate (FHR) and femoral blood flow (FBF), with initial hypertension, followed by progressive development of hypotension during ongoing occlusions. Sympathectomy was associated with attenuation of the initial rise in MAP during umbilical cord occlusion, and after the onset of hypotension, a markedly more rapid fall of MAP to the nadir, with a correspondingly slower fall in FBF (P < 0.05). In contrast, MAP and FHR between successive occlusions were higher after sympathectomy (P < 0.05). There was no significant difference in the number of occlusions before terminal hypotension (6-OHDA; 16.1 ± 2.2 vs. control; 18.7 ± 2.3). These data show that SNS activity provides ongoing support for fetal MAP during prolonged exposure to brief repeated asphyxia.
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Affiliation(s)
- Robert Galinsky
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Ellen C Jensen
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Clinton J Mitchell
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Eleanor R Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Guido Wassink
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Mhoyra Fraser
- Department of Physiology, University of Auckland, Auckland, New Zealand; and The Liggins Institute, University of Auckland, Auckland, New Zealand
| | - Jennifer A Westgate
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand; and
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19
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Booth LC, Malpas SC, Barrett CJ, Guild SJ, Gunn AJ, Bennet L. Renal sympathetic nerve activity during asphyxia in fetal sheep. Am J Physiol Regul Integr Comp Physiol 2012; 303:R30-8. [PMID: 22552793 DOI: 10.1152/ajpregu.00063.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sympathetic nervous system (SNS) is an important mediator of fetal adaptation to life-threatening in utero challenges, such as asphyxia. Although the SNS is active well before term, SNS responses mature significantly over the last third of gestation, and its functional contribution to adaptation to asphyxia over this critical period of life remains unclear. Therefore, we examined the hypotheses that increased renal sympathetic nerve activity (RSNA) is the primary mediator of decreased renal vascular conductance (RVC) during complete umbilical cord occlusion in preterm fetal sheep (101 ± 1 days; term 147 days) and that near-term fetuses (119 ± 0 days) would have a more rapid initial vasomotor response, with a greater increase in RSNA. Causality of the relationship of RSNA and RVC was investigated using surgical (preterm) and chemical (near-term) denervation. All fetal sheep showed a significant increase in RSNA with occlusion, which was more sustained but not significantly greater near-term. The initial fall in RVC was more rapid in near-term than preterm fetal sheep and preceded the large increase in RSNA. These data suggest that although RSNA can increase as early as 0.7 gestation, it is not the primary determinant of RVC. This finding was supported by denervation studies. Interestingly, chemical denervation in near-term fetal sheep was associated with an initial fall in blood pressure, suggesting that by 0.8 gestation sympathetic innervation of nonrenal vascular beds is critical to maintain arterial blood pressure during the rapid initial adaptation to asphyxia.
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Affiliation(s)
- Lindsea C Booth
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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20
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Kent AL, Wright IMR, Abdel-Latif ME. Mortality and adverse neurologic outcomes are greater in preterm male infants. Pediatrics 2012; 129:124-31. [PMID: 22184652 DOI: 10.1542/peds.2011-1578] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES To determine whether male gender has an effect on survival, early neonatal morbidity, and long-term outcome in neonates born extremely prematurely. METHODS Retrospective review of the New South Wales and Australian Capital Territory Neonatal Intensive Care Unit Data Collection of all infants admitted to New South Wales and Australian Capital Territory neonatal intensive care units between January 1998 and December 2004. The primary outcome was hospital mortality and functional impairment at 2 to 3 years follow-up. RESULTS Included in the study were 2549 neonates; 54.7% were male. Risks of grade III/IV intraventricular hemorrhage, sepsis, and major surgery were found to be increased in male neonates. Hospital mortality (odds ratio 1.285, 95% confidence interval 1.035-1.595) and moderate to severe functional disability at 2 to 3 years of age (odds ratio 1.877, 95% confidence interval 1.398-2.521) were more likely in male infants. Gender differences for mortality and long-term neurologic outcome loses significance at 27 weeks gestation. CONCLUSIONS In the modern era of neonatal management, male infants still have higher mortality and poorer long-term neurologic outcome. Gender differences for mortality and long-term neurologic outcome appear to lose significance at 27 weeks gestation.
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Affiliation(s)
- Alison L Kent
- Department of Neonatology, Canberra Hospital, PO Box 11, Woden, 2606, ACT, Australia.
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21
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Lindgren I, Crossley D, Villamor E, Altimiras J. Hypotension in the chronically hypoxic chicken embryo is related to the β-adrenergic response of chorioallantoic and femoral arteries and not to bradycardia. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1161-8. [DOI: 10.1152/ajpregu.00458.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prolonged fetal hypoxia leads to growth restriction and can cause detrimental prenatal and postnatal alterations. The embryonic chicken is a valuable model to study the effects of prenatal hypoxia, but little is known about its long-term effects on cardiovascular regulation. We hypothesized that chicken embryos incubated under chronic hypoxia would be hypotensive due to bradycardia and βAR-mediated relaxation of the systemic and/or the chorioallantoic (CA) arteries. We investigated heart rate, blood pressure, and plasma catecholamine levels in 19-day chicken embryos (total incubation 21 days) incubated from day 0 in normoxia or hypoxia (14–15% O2). Additionally, we studied α-adrenoceptor (αAR)-mediated contraction, relaxation to the β-adrenoceptor (βAR) agonist isoproterenol, and relaxation to the adenylate cyclase activator forskolin in systemic (femoral) and CA arteries (by wire myography). Arterial pressure showed a trend toward hypotension in embryos incubated under chronic hypoxic conditions compared with the controls (mean arterial pressure 3.19 ± 0.18 vs. 2.59 ± 0.13 kPa, normoxia vs. hypoxia, respectively. P = 0.056), without an accompanied bradycardia and elevation in plasma norepinephrine and lactate levels. All vessels relaxed in response to βAR stimulation with isoproterenol, but the CA arteries completely lacked an αAR response. Furthermore, hypoxia increased the sensitivity of femoral arteries (but not CA arteries) to isoproterenol. Hypoxia also increased the responsiveness of femoral arteries to forskolin. In conclusion, we suggest that hypotension in chronic hypoxic chicken embryos is the consequence of elevated levels of circulating catecholamines acting in vascular beds with exclusive (CA arteries) or exacerbated (femoral arteries) βAR-mediated relaxation, and not a consequence of bradycardia.
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Affiliation(s)
- Isa Lindgren
- IFM Biology, Division of Zoology, Linköping University, Linköping, Sweden
| | - Dane Crossley
- Department of Biological Sciences, University of North Texas, Denton, Texas; and
| | - Eduardo Villamor
- Department of Pediatrics, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
| | - Jordi Altimiras
- IFM Biology, Division of Zoology, Linköping University, Linköping, Sweden
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22
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Gunn AJ, Bennet L. Fetal hypoxia insults and patterns of brain injury: insights from animal models. Clin Perinatol 2009; 36:579-93. [PMID: 19732615 PMCID: PMC2767254 DOI: 10.1016/j.clp.2009.06.007] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The outcome of perinatal hypoxiaischemia is highly variable, with only a very broad relationship to the 'severity' of oxygen debt as shown by peripheral base deficit and the risk of damage. The present article examines the pathophysiology of asphyxial injury. We dissect the multiple factors that modify the risk of injury, including the depth ('severity'), duration, and repetition of the insult, the maturity, and condition of the fetus, pre-existing hypoxia, and exposure to pyrexia and infection/inflammation.
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Affiliation(s)
- Alistair Jan Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, 85 Park Road, Grafton, Auckland 1023, New Zealand.
| | - Laura Bennet
- Professor, Dept of Physiology, University of Auckland, Auckland, New Zealand
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23
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Abstract
This article examines recent studies that have systematically dissected features of fetal heart rate responses to labor that may help identify developing fetal compromise, such as the slope of the deceleration, overshoot, and variability. Although repeated deep decelerations are never necessarily benign, fetuses with normal placental reserve can fully compensate even for frequent deep but brief decelerations for surprisingly prolonged intervals before developing profound acidosis and hypotension.
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Affiliation(s)
- Laura Bennet
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
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24
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Harris TA, Healy GN, Colditz PB, Lingwood BE. Oscillations in cardiovascular function during acute hypoxia in the newborn piglet are associated with less neurological damage and occur more frequently in females. Pediatr Res 2009; 65:504-8. [PMID: 19190542 DOI: 10.1203/pdr.0b013e31819d9747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The function of the cardiovascular system during hypoxia is an important determinant of neurologic outcome. Oscillations in blood pressure, particularly type-3 waves with a duration of 10 to 160 s, have been shown to occur in the presence of hypoxia in the neonatal rat. The aim of this study was to determine the characteristics and occurrence of type-3 waves in the neonatal piglet and any relationship to neurologic damage after acute global hypoxia. Hypoxia/hypercarbia was induced in 32 anesthetized piglets by reducing the fraction of inspired oxygen to 0.1 and the ventilation rate from 30 to 10 breaths per minute for 45 min. The degree of neurologic damage was assessed using both physiologic (EEG amplitude and cerebral impedance at 6 h posthypoxia) and structural (microtubule associated protein-2 immunohistochemistry) markers. Type-3 waves in cardiovascular function occurred in 56% of animals. An oscillating pattern was significantly associated with less neurologic damage (p = 0.01) and a lower duration of hypotension during hypoxia (p = 0.02), and occurred more frequently in females (p = 0.024).
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Affiliation(s)
- Thomas A Harris
- Perinatal Research Centre, University of Queensland Centre for Clinical Research, The University of Queensland, Royal Brisbane and Women's Hospital, Queensland, Australia 4029
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25
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Bernardes J, Gonçalves H, Ayres-de-Campos D, Rocha AP. Sex differences in linear and complex fetal heart rate dynamics of normal and acidemic fetuses in the minutes preceding delivery. J Perinat Med 2009; 37:168-76. [PMID: 19021459 DOI: 10.1515/jpm.2009.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AIM To assess linear and complex heart rate dynamics in relation to fetal gender in normal and acidemic fetuses during the minutes preceding delivery. METHODS Linear and non-linear fetal heart rate indices, namely mean FHR, long-term irregularity index, short-term variability, low and high frequency spectral indices, approximate and sample entropy, were assessed in 36 female and 30 male fetuses, adjusted for gestational age and weight, during the minutes preceding delivery. Analysis was performed in the initial and final minutes of each tracing in fetuses with umbilical artery blood pH at delivery >or=7.20, 7.11-7.19 and <or=7.10. RESULTS Progression of labor was associated with a significant decrease in non-linear indices and an increase in almost all linear indices, both in female and male fetuses, but changes were more marked in female fetuses. Non-acidemic females showed higher mean FHR in the final minutes of labor, compared with males. Acidemic females had higher linear indices when compared to similar male fetuses. CONCLUSIONS During the minutes preceding delivery, female fetuses express higher linear indices than male fetuses, suggesting greater activation of the autonomic nervous system, while maintaining similar complexity indices, which suggests different reaction and adaptation capabilities to stress and distress.
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Affiliation(s)
- João Bernardes
- Departamento de Ginecologia e Obstetrícia, Faculdade de Medicina da Universidade do Porto, Hospital de S. João, Porto and Instituto Nacional de Engenharia Biomédica (INEB), Porto, Portugal.
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26
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Davidson JO, Fraser M, Naylor AS, Roelfsema V, Gunn AJ, Bennet L. Effect of cerebral hypothermia on cortisol and adrenocorticotropic hormone responses after umbilical cord occlusion in preterm fetal sheep. Pediatr Res 2008; 63:51-5. [PMID: 18043499 DOI: 10.1203/pdr.0b013e31815b8eb4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis is essential for adaptation to stress. In the present study, we examined the hypothesis that head cooling with mild systemic hypothermia would adversely affect fetal adrenocorticotropic hormone (ACTH) and cortisol responses to an asphyxial insult. Chronically instrumented preterm fetal sheep (104 d of gestation, term is 147 d) were allocated to sham occlusion (n = 7), 25 min of complete umbilical cord occlusion (n = 7), or occlusion and head cooling with mild systemic hypothermia (n = 7, mean +/- SEM esophageal temperature 37.6 +/- 0.3 degrees C vs 39.0 +/- 0.2 degrees C; p < 0.05) from 90 min to 70 h after occlusion, followed by spontaneous rewarming. During umbilical cord occlusion, there was a rapid rise in ACTH and cortisol levels, with further increases after release of cord occlusion. ACTH levels returned to sham control values after 10 h in both occlusion groups. In contrast, plasma cortisol levels remained elevated after 48 h in both occlusion groups and were still significantly elevated in the hypothermia-occlusion group 2 h after rewarming, at 72 h, compared with the normothermia-occlusion and sham groups. In conclusion, hypothermia does not affect the overall HPA responses to severe asphyxia in the preterm fetus but does prolong the cortisol response.
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Affiliation(s)
- Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland 1023, New Zealand
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