1
|
泽 碧, 高 瑾, 赵 晓, 李 杨, 张 铁, 刘 晓, 毛 辉, 秦 明, 张 奕, 杨 永, 和 春, 赵 燕, 杜 琨, 刘 玲, 周 文. [Cerebral oxygen metabolism and brain electrical activity of healthy full-term neonates in high-altitude areas: a multicenter clinical research protocol]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2024; 26:403-409. [PMID: 38660905 PMCID: PMC11057305 DOI: 10.7499/j.issn.1008-8830.2310102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 02/26/2024] [Indexed: 04/26/2024]
Abstract
Further evidence is needed to explore the impact of high-altitude environments on the neurologic function of neonates. Non-invasive techniques such as cerebral near-infrared spectroscopy and amplitude-integrated electroencephalography can provide data on cerebral oxygenation and brain electrical activity. This study will conduct multiple cerebral near-infrared spectroscopy and amplitude-integrated electroencephalography monitoring sessions at various time points within the first 3 days postpartum for healthy full-term neonates at different altitudes. The obtained data on cerebral oxygenation and brain electrical activity will be compared between different altitudes, and corresponding reference ranges will be established. The study involves 6 participating centers in the Chinese High Altitude Neonatal Medicine Alliance, with altitude gradients divided into 4 categories: 800 m, 1 900 m, 2 400 m, and 3 500 m, with an anticipated sample size of 170 neonates per altitude gradient. This multicenter prospective cohort study aims to provide evidence supporting the impact of high-altitude environments on early brain function and metabolism in neonates.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - 明彩 秦
- 云南迪庆藏族自治州香格里拉市妇幼保健院儿科,云南迪庆藏族自治州674400
| | - 奕 张
- 云南迪庆藏族自治州人民医院儿科,云南迪庆藏族自治州674400
| | - 永礼 杨
- 云南省丽江市妇幼保健院 儿科,云南丽江674100
| | | | - 燕 赵
- 云南省怒江傈僳族自治州人民医院儿科,云南怒江671400
| | | | | | - 文浩 周
- 广州市妇女儿童医疗中心新生儿科,广东广州510000
| |
Collapse
|
2
|
Ehrenreich H, Gassmann M, Poustka L, Burtscher M, Hammermann P, Sirén AL, Nave KA, Miskowiak K. Exploiting moderate hypoxia to benefit patients with brain disease: Molecular mechanisms and translational research in progress. NEUROPROTECTION 2023; 1:9-19. [PMID: 37671067 PMCID: PMC7615021 DOI: 10.1002/nep3.15] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/17/2022] [Indexed: 09/07/2023]
Abstract
Hypoxia is increasingly recognized as an important physiological driving force. A specific transcriptional program, induced by a decrease in oxygen (O2) availability, for example, inspiratory hypoxia at high altitude, allows cells to adapt to lower O2 and limited energy metabolism. This transcriptional program is partly controlled by and partly independent of hypoxia-inducible factors. Remarkably, this same transcriptional program is stimulated in the brain by extensive motor-cognitive exercise, leading to a relative decrease in O2 supply, compared to the acutely augmented O2 requirement. We have coined the term "functional hypoxia" for this important demand-responsive, relative reduction in O2 availability. Functional hypoxia seems to be critical for enduring adaptation to higher physiological challenge that includes substantial "brain hardware upgrade," underlying advanced performance. Hypoxia-induced erythropoietin expression in the brain likely plays a decisive role in these processes, which can be imitated by recombinant human erythropoietin treatment. This article review presents hints of how inspiratory O2 manipulations can potentially contribute to enhanced brain function. It thereby provides the ground for exploiting moderate inspiratory plus functional hypoxia to treat individuals with brain disease. Finally, it sketches a planned multistep pilot study in healthy volunteers and first patients, about to start, aiming at improved performance upon motor-cognitive training under inspiratory hypoxia.
Collapse
Affiliation(s)
- Hannelore Ehrenreich
- Clinical Neuroscience, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Max Gassmann
- Institute of Veterinary Physiology and Zürich Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland
| | - Luise Poustka
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Medical Center Göttingen, Göttingen, Germany
| | - Martin Burtscher
- Faculty of Sports Science, University of Innsbruck, Innsbruck, Austria
| | | | - Anna-Leena Sirén
- Departments of Neurophysiology and Neurosurgery, University of Würzburg, Würzburg, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Kamilla Miskowiak
- Psychiatric Centre, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Psychology, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
3
|
Aboouf MA, Thiersch M, Soliz J, Gassmann M, Schneider Gasser EM. The Brain at High Altitude: From Molecular Signaling to Cognitive Performance. Int J Mol Sci 2023; 24:10179. [PMID: 37373327 DOI: 10.3390/ijms241210179] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/13/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
The brain requires over one-fifth of the total body oxygen demand for normal functioning. At high altitude (HA), the lower atmospheric oxygen pressure inevitably challenges the brain, affecting voluntary spatial attention, cognitive processing, and attention speed after short-term, long-term, or lifespan exposure. Molecular responses to HA are controlled mainly by hypoxia-inducible factors. This review aims to summarize the cellular, metabolic, and functional alterations in the brain at HA with a focus on the role of hypoxia-inducible factors in controlling the hypoxic ventilatory response, neuronal survival, metabolism, neurogenesis, synaptogenesis, and plasticity.
Collapse
Affiliation(s)
- Mostafa A Aboouf
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich, 8057 Zurich, Switzerland
- Department of Biochemistry, Faculty of Pharmacy, Ain Shams University, Cairo 11566, Egypt
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland
| | - Markus Thiersch
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich, 8057 Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland
| | - Jorge Soliz
- Institute Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ), Faculty of Medicine, Université Laval, Québec, QC G1V 4G5, Canada
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich, 8057 Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland
| | - Edith M Schneider Gasser
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich, 8057 Zurich, Switzerland
- Institute Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ), Faculty of Medicine, Université Laval, Québec, QC G1V 4G5, Canada
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland
| |
Collapse
|
4
|
Schabel MC, Roberts VHJ, Gibbins KJ, Rincon M, Gaffney JE, Streblow AD, Wright AM, Lo JO, Park B, Kroenke CD, Szczotka K, Blue NR, Page JM, Harvey K, Varner MW, Silver RM, Frias AE. Quantitative longitudinal T2* mapping for assessing placental function and association with adverse pregnancy outcomes across gestation. PLoS One 2022; 17:e0270360. [PMID: 35853003 PMCID: PMC9295947 DOI: 10.1371/journal.pone.0270360] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/09/2022] [Indexed: 11/21/2022] Open
Abstract
Existing methods for evaluating in vivo placental function fail to reliably detect pregnancies at-risk for adverse outcomes prior to maternal and/or fetal morbidity. Here we report the results of a prospective dual-site longitudinal clinical study of quantitative placental T2* as measured by blood oxygen-level dependent magnetic resonance imaging (BOLD-MRI). The objectives of this study were: 1) to quantify placental T2* at multiple time points across gestation, and its consistency across sites, and 2) to investigate the association between placental T2* and adverse outcomes. 797 successful imaging studies, at up to three time points between 11 and 38 weeks of gestation, were completed in 316 pregnancies. Outcomes were stratified into three groups: (UN) uncomplicated/normal pregnancy, (PA) primary adverse pregnancy, which included hypertensive disorders of pregnancy, birthweight <5th percentile, and/or stillbirth or fetal death, and (SA) secondary abnormal pregnancy, which included abnormal prenatal conditions not included in the PA group such as spontaneous preterm birth or fetal anomalies. Of the 316 pregnancies, 198 (62.6%) were UN, 70 (22.2%) PA, and 48 (15.2%) SA outcomes. We found that the evolution of placental T2* across gestation was well described by a sigmoid model, with T2* decreasing continuously from a high plateau level early in gestation, through an inflection point around 30 weeks, and finally approaching a second, lower plateau in late gestation. Model regression revealed significantly lower T2* in the PA group than in UN pregnancies starting at 15 weeks and continuing through 33 weeks. T2* percentiles were computed for individual scans relative to UN group regression, and z-scores and receiver operating characteristic (ROC) curves calculated for association of T2* with pregnancy outcome. Overall, differences between UN and PA groups were statistically significant across gestation, with large effect sizes in mid- and late- pregnancy. The area under the curve (AUC) for placental T2* percentile and PA pregnancy outcome was 0.71, with the strongest predictive power (AUC of 0.76) at the mid-gestation time period (20–30 weeks). Our data demonstrate that placental T2* measurements are strongly associated with pregnancy outcomes often attributed to placental insufficiency. Trial registration: ClinicalTrials.gov: NCT02749851.
Collapse
Affiliation(s)
- Matthias C. Schabel
- Advanced Imaging Research Center, Oregon Health and Science University (OHSU), Portland, Oregon, United States of America
| | - Victoria H. J. Roberts
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center (ONPRC), OHSU, Portland, Oregon, United States of America
- * E-mail:
| | - Karen J. Gibbins
- Department of Obstetrics and Gynecology, OHSU, Portland, Oregon, United States of America
| | - Monica Rincon
- Department of Obstetrics and Gynecology, OHSU, Portland, Oregon, United States of America
| | - Jessica E. Gaffney
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center (ONPRC), OHSU, Portland, Oregon, United States of America
| | - Aaron D. Streblow
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center (ONPRC), OHSU, Portland, Oregon, United States of America
| | - Adam M. Wright
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center (ONPRC), OHSU, Portland, Oregon, United States of America
| | - Jamie O. Lo
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center (ONPRC), OHSU, Portland, Oregon, United States of America
- Department of Obstetrics and Gynecology, OHSU, Portland, Oregon, United States of America
| | - Byung Park
- Biostatistics Shared Resource, Knight Cancer Institute, OHSU, Portland, Oregon, United States of America
| | - Christopher D. Kroenke
- Advanced Imaging Research Center, Oregon Health and Science University (OHSU), Portland, Oregon, United States of America
- Division of Neuroscience, ONPRC, OHSU, Portland, Oregon, United States of America
| | - Kathryn Szczotka
- Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah, United States of America
| | - Nathan R. Blue
- Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah, United States of America
| | - Jessica M. Page
- Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah, United States of America
| | - Kathy Harvey
- Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah, United States of America
| | - Michael W. Varner
- Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah, United States of America
| | - Robert M. Silver
- Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah, United States of America
| | - Antonio E. Frias
- Department of Obstetrics and Gynecology, OHSU, Portland, Oregon, United States of America
| |
Collapse
|
5
|
Ortiz-Prado E, Cordovez SP, Vasconez E, Viscor G, Roderick P. Chronic high-altitude exposure and the epidemiology of ischaemic stroke: a systematic review. BMJ Open 2022; 12:e051777. [PMID: 35487749 PMCID: PMC9058702 DOI: 10.1136/bmjopen-2021-051777] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION About 5.7% of the world population resides above 1500 m. It has been hypothesised that acute exposure to high-altitude locations can increase stroke risk, while chronic hypoxia can reduce stroke-related mortality. OBJECTIVE This review aims to provide an overview of the available evidence on the association between long-term high-altitude exposure and ischaemic stroke. DESIGN A systematic review was performed from 1 January 1960 to 1 December 2021 to assess the possible link between high-altitude exposure and ischaemic stroke. The AMED, EMBASE, Cochrane Library, PubMed, MEDLINE, the Europe PubMed Central and the Latin-American bibliographic database Scielo were accessed using the University of Southampton library tool Delphis. In this review, we included population and individual-based observational studies, including cross-sectional and longitudinal studies except for those merely descriptive individual-based case reports. Studies were limited to humans living or visiting high-altitude locations for at least 28 days as a cut-off point for chronic exposure. RESULTS We reviewed a total of 1890 abstracts retrieved during the first step of the literature review process. The authors acquired in full text as potentially relevant 204 studies. Only 17 documents met the inclusion criteria and were finally included. Ten studies clearly suggest that living at high altitudes may be associated with an increased risk of stroke; however, five studies suggest that altitude may act as a protective factor for the development of stroke, while two studies report ambiguous results. CONCLUSIONS This review suggests that the most robust studies are more likely to find that prolonged living at higher altitudes reduces the risk of developing stroke or dying from it. Increased irrigation due to angiogenesis and increased vascular perfusion might be the reason behind improved survival profiles among those living within this altitude range. In contrast, residing above 3500 m seems to be associated with an apparent increased risk of developing stroke, probably linked to the presence of polycythaemia and other associated factors such as increased blood viscosity.
Collapse
Affiliation(s)
- Esteban Ortiz-Prado
- One Health Research Group, Universidad de Las Américas, Quito, Ecuador
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
| | - Simone Pierina Cordovez
- One Health Research Group, Universidad de Las Américas, Quito, Ecuador
- Facultad de Medicina, Universidad San Gregorio de Portoviejo, Portoviejo, Manabi, Ecuador
| | - Eduardo Vasconez
- One Health Research Group, Universidad de Las Américas, Quito, Ecuador
| | - Ginés Viscor
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
| | - Paul Roderick
- Faculty of Medicine, University of Southampton, Southampton, UK
| |
Collapse
|
6
|
Gonzalez-Candia A, Herrera EA. High Altitude Pregnancies and Vascular Dysfunction: Observations From Latin American Studies. Front Physiol 2021; 12:786038. [PMID: 34950057 PMCID: PMC8688922 DOI: 10.3389/fphys.2021.786038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/02/2021] [Indexed: 12/14/2022] Open
Abstract
An estimated human population of 170 million inhabit at high-altitude (HA, above 2,500 m). The potential pathological effects of HA hypobaric hypoxia during gestation have been the focus of several researchers around the world. The studies based on the Himalayan and Central/South American mountains are particularly interesting as these areas account for nearly 70% of the HA world population. At present, studies in human and animal models revealed important alterations in fetal development and growth at HA. Moreover, vascular responses to chronic hypobaria in the pregnant mother and her fetus may induce marked cardiovascular impairments during pregnancy or in the neonatal period. In addition, recent studies have shown potential long-lasting postnatal effects that may increase cardiovascular risk in individuals gestated under chronic hypobaria. Hence, the maternal and fetal adaptive responses to hypoxia, influenced by HA ancestry, are vital for a better developmental and cardiovascular outcome of the offspring. This mini-review exposes and discusses the main determinants of vascular dysfunction due to developmental hypoxia at HA, such as the Andean Mountains, at the maternal and fetal/neonatal levels. Although significant advances have been made from Latin American studies, this area still needs further investigations to reveal the mechanisms involved in vascular dysfunction, to estimate complications of pregnancy and postnatal life adequately, and most importantly, to determine potential treatments to prevent or treat the pathological effects of being developed under chronic hypobaric hypoxia.
Collapse
Affiliation(s)
- Alejandro Gonzalez-Candia
- Laboratorio de Función y Reactividad Vascular, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Instituto de Ciencias de la Salud, Universidad de O'Higgins, Rancagua, Chile
| | - Emilio A Herrera
- Laboratorio de Función y Reactividad Vascular, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,International Center for Andean Studies (INCAS), Universidad de Chile, Santiago, Chile
| |
Collapse
|
7
|
Mairbäurl H. Squeezing viscous blood through narrow pipes, and other problems of high-altitude polycythaemia. J Physiol 2021; 599:4011-4012. [PMID: 34333786 DOI: 10.1113/jp282104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Heimo Mairbäurl
- Translational Pneumology, University Hospital Heidelberg, Heidelberg, Baden-Wurttemberg, Germany
| |
Collapse
|
8
|
Dueñas-Espín I, Armijos-Acurio L, Espín E, Espinosa-Herrera F, Jimbo R, León-Cáceres Á, Nasre-Nasser R, Rivadeneira MF, Rojas-Rueda D, Ruiz-Cedeño L, Tello B, Vásconez-Romero D. Is a higher altitude associated with shorter survival among at-risk neonates? PLoS One 2021; 16:e0253413. [PMID: 34260612 PMCID: PMC8279317 DOI: 10.1371/journal.pone.0253413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/04/2021] [Indexed: 11/21/2022] Open
Abstract
INTRODUCTION We hypothesize that high altitudes could have an adverse effect on neonatal health outcomes, especially among at-risk neonates. The current study aims to assess the association between higher altitudes on survival time among at-risk neonates. METHODS Retrospective survival analysis. Setting: Ecuadorian neonates who died at ≤28 days of life. Patients: We analyzed the nationwide dataset of neonatal deaths from the Surveillance System of Neonatal Mortality of the Ministry of Public Health of Ecuador, registered from 126 public and private health care facilities, between January 2014 to September 2017. Main outcome measures: We retrospectively reviewed 3016 patients. We performed a survival analysis by setting the survival time in days as the primary outcome and fixed and mixed-effects Cox proportional hazards models to estimate hazard ratios (HR) for each altitude stratum of each one of the health care facilities in which those neonates were attended, adjusting by individual variables (i.e., birth weight, gestational age at birth, Apgar scale at 5 minutes, and comorbidities); and contextual variables (i.e., administrative planning areas, type of health care facility, and level of care). RESULTS Altitudes of health care facilities ranging from 80 to <2500 m, 2500 to <2750m, and ≥2750 m were associated respectively with 20% (95% CI: 1% to 44%), 32% (95% CI:<1% to 79%) and 37% (95% CI: 8% to 75%) increased HR; compared with altitudes at <80 m. CONCLUSION Higher altitudes are independently associated with shorter survival time, as measured by days among at-risk neonates. Altitude should be considered when assessing the risk of having negative health outcomes during neonatal period.
Collapse
Affiliation(s)
- Iván Dueñas-Espín
- Instituto de Salud Pública, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| | - Luciana Armijos-Acurio
- Instituto de Salud Pública, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| | - Estefanía Espín
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad de las Américas (UDLA) and Facultad de Medicina, Universidad Central del Ecuador, Quito, Ecuador
| | - Fernando Espinosa-Herrera
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad de las Américas (UDLA) and Facultad de Medicina, Universidad Central del Ecuador, Quito, Ecuador
- Sociedad Ecuatoriana de Medicina Familiar (SEMF), Quito, Ecuador
| | - Ruth Jimbo
- Instituto de Salud Pública, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| | - Ángela León-Cáceres
- Instituto de Salud Pública, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
- Heidelberg Institute of Global Health, Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
- Tropical Herping, Quito, Ecuador
| | - Raif Nasre-Nasser
- Programa de Pós-graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), Rio Grande, Brasil
| | - María F. Rivadeneira
- Instituto de Salud Pública, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| | - David Rojas-Rueda
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Laura Ruiz-Cedeño
- Postgrado de Pediatría, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| | - Betzabé Tello
- Instituto de Salud Pública, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| | - Daniela Vásconez-Romero
- Postgrado de Pediatría, Facultad de Medicina, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador
| |
Collapse
|
9
|
Mouradian GC, Lakshminrusimha S, Konduri GG. Perinatal Hypoxemia and Oxygen Sensing. Compr Physiol 2021; 11:1653-1677. [PMID: 33792908 DOI: 10.1002/cphy.c190046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The development of the control of breathing begins in utero and continues postnatally. Fetal breathing movements are needed for establishing connectivity between the lungs and central mechanisms controlling breathing. Maturation of the control of breathing, including the increase of hypoxia chemosensitivity, continues postnatally. Insufficient oxygenation, or hypoxia, is a major stressor that can manifest for different reasons in the fetus and neonate. Though the fetus and neonate have different hypoxia sensing mechanisms and respond differently to acute hypoxia, both responses prevent deviations to respiratory and other developmental processes. Intermittent and chronic hypoxia pose much greater threats to the normal developmental respiratory processes. Gestational intermittent hypoxia, due to maternal sleep-disordered breathing and sleep apnea, increases eupneic breathing and decreases the hypoxic ventilatory response associated with impaired gasping and autoresuscitation postnatally. Chronic fetal hypoxia, due to biologic or environmental (i.e. high-altitude) factors, is implicated in fetal growth restriction and preterm birth causing a decrease in the postnatal hypoxic ventilatory responses with increases in irregular eupneic breathing. Mechanisms driving these changes include delayed chemoreceptor development, catecholaminergic activity, abnormal myelination, increased astrocyte proliferation in the dorsal respiratory group, among others. Long-term high-altitude residents demonstrate favorable adaptations to chronic hypoxia as do their offspring. Neonatal intermittent hypoxia is common among preterm infants due to immature respiratory systems and thus, display a reduced drive to breathe and apneas due to insufficient hypoxic sensitivity. However, ongoing intermittent hypoxia can enhance hypoxic sensitivity causing ventilatory overshoots followed by apnea; the number of apneas is positively correlated with degree of hypoxic sensitivity in preterm infants. Chronic neonatal hypoxia may arise from fetal complications like maternal smoking or from postnatal cardiovascular problems, causing blunting of the hypoxic ventilatory responses throughout at least adolescence due to attenuation of carotid body fibers responses to hypoxia with potential roles of brainstem serotonin, microglia, and inflammation, though these effects depend on the age in which chronic hypoxia initiates. Fetal and neonatal intermittent and chronic hypoxia are implicated in preterm birth and complicate the respiratory system through their direct effects on hypoxia sensing mechanisms and interruptions to the normal developmental processes. Thus, precise regulation of oxygen homeostasis is crucial for normal development of the respiratory control network. © 2021 American Physiological Society. Compr Physiol 11:1653-1677, 2021.
Collapse
Affiliation(s)
- Gary C Mouradian
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Satyan Lakshminrusimha
- Department of Pediatrics, UC Davis Children's Hospital, UC Davis Health, UC Davis, Davis, California, USA
| | - Girija G Konduri
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| |
Collapse
|
10
|
Ze B, Liu L, Yang Jin GS, Shan M, Geng Y, Zhou C, Wu T, Wu H, Hou X. Near-Infrared Spectroscopy Monitoring of Cerebral Oxygenation and Influencing Factors in Neonates from High-Altitude Areas. Neonatology 2021; 118:348-353. [PMID: 34107488 DOI: 10.1159/000514403] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 12/21/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Accurate detection of cerebral oxygen saturation (rSO2) may be useful for neonatal brain injury prevention, and the normal range of rSO2 of neonates at high altitude remained unclear. OBJECTIVE To compare cerebral rSO2 and cerebral fractional tissue oxygen extraction (cFTOE) at high-altitude and low-altitude areas in healthy neonates and neonates with underlying diseases. METHODS 515 neonates from low-altitude areas and 151 from Tibet were enrolled. These neonates were assigned into the normal group, hypoxic-ischemic encephalopathy (HIE) group, and other diseases group. Near-infrared spectroscopy was used to measure rSO2 in neonates within 24 h after admission. The differences of rSO2, pulse oxygen saturation (SpO2), and cFTOE levels were compared between neonates from low- and high-altitude areas. RESULTS (1) The mean rSO2 and cFTOE levels in normal neonates from Tibet were 55.0 ± 6.4% and 32.6 ± 8.5%, significantly lower than those from low-altitude areas (p < 0.05). (2) At high altitude, neonates with HIE, pneumonia (p < 0.05), anemia, and congenital heart disease (p < 0.05) have higher cFTOE than healthy neonates. (3) Compared with HIE neonates from plain areas, neonates with HIE at higher altitude had lower cFTOE (p < 0.05), while neonates with heart disease in plateau areas had higher cFTOE than those in plain areas (p < 0.05). CONCLUSIONS The rSO2 and cFTOE levels in normal neonates from high-altitude areas are lower than neonates from the low-altitude areas. Lower cFTOE is possibly because of an increase in blood flow to the brain, and this may be adversely affected by disease states which may increase the risk of brain injury.
Collapse
Affiliation(s)
- Bi Ze
- Pediatric Department, Peking University First Hospital, Beijing, China.,Pediatric Department, Tibet Autonomous Region People's Hospital, Lhasa, China
| | - Lili Liu
- Pediatric Department, Peking University First Hospital, Beijing, China
| | - Ge Sang Yang Jin
- Pediatric Department, Tibet Autonomous Region People's Hospital, Lhasa, China
| | - Minna Shan
- Pediatric Department, Tibet Autonomous Region People's Hospital, Lhasa, China
| | - Yuehang Geng
- Pediatric Department, Peking University First Hospital, Beijing, China
| | - Congle Zhou
- Pediatric Department, Peking University First Hospital, Beijing, China
| | - Tianqi Wu
- Pediatric Department, Tibet Autonomous Region People's Hospital, Lhasa, China
| | - Hong Wu
- Pediatric Department, Tibet Autonomous Region People's Hospital, Lhasa, China
| | - Xinlin Hou
- Pediatric Department, Peking University First Hospital, Beijing, China.,Pediatric Department, Tibet Autonomous Region People's Hospital, Lhasa, China
| |
Collapse
|
11
|
Mairbäurl H, Gassmann M, Muckenthaler MU. Geographical ancestry affects normal hemoglobin values in high-altitude residents. J Appl Physiol (1985) 2020; 129:1451-1459. [PMID: 33002380 DOI: 10.1152/japplphysiol.00025.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Increasing the hemoglobin (Hb) concentration is a major mechanism adjusting arterial oxygen content to decreased oxygen partial pressure of inspired air at high altitude. Approximately 5% of the world's population living at altitudes higher than 1,500 m shows this adaptive mechanism. Notably, there is a wide variation in the extent of increase in Hb concentration among different populations. This short review summarizes available information on Hb concentrations of high-altitude residents living at comparable altitudes (3,500-4,500 m) in different regions of the world. An increased Hb concentration is found in all high-altitude populations. The highest mean Hb concentration was found in adult male Andean residents and in Han Chinese living at high altitude, whereas it was lowest in Ethiopians, Tibetans, and Sherpas. A lower plasma volume in Andean high-altitude natives may offer a partial explanation. Indeed, male Andean high-altitude natives have a lower plasma volume than Tibetans and Ethiopians. Moreover, Hb values were lower in adult, nonpregnant females than in males; differences between populations of different ancestry were less pronounced. Various genetic polymorphisms were detected in high-altitude residents thought to favor life in a hypoxic environment, some of which correlate with the relatively low Hb concentration in the Tibetans and Ethiopians, whereas differences in angiotensin-converting enzyme allele distribution may be related to elevated Hb in the Andeans. Taken together, these results indicate different sensitivity of oxygen dependent control of erythropoiesis or plasma volume among populations of different geographical ancestry, offering explanations for differences in the Hb concentration at high altitude.
Collapse
Affiliation(s)
- Heimo Mairbäurl
- Departmment of Translational Pneumology, University Hospital Heidelberg, Heidelberg, Germany.,Translational Lung Research Center Heidelberg, Member of the German Center for Lung Research, Heidelberg, Germany
| | - Max Gassmann
- Vetsuisse Faculty, Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.,Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Martina U Muckenthaler
- Translational Lung Research Center Heidelberg, Member of the German Center for Lung Research, Heidelberg, Germany.,Departmment of Pediatric Hematology, Oncology and Immunology, University Hospital Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit, University of Heidelberg, Heidelberg, Germany.,German Centre for Cardiovascular Research, Partner Site Heidelberg/Mannheim, Germany
| |
Collapse
|
12
|
Jin M, Lu J, Fei X, Lu Z, Quan K, Liu Y, Chu M, Di R, Wei C, Wang H. Selection Signatures Analysis Reveals Genes Associated with High-Altitude Adaptation in Tibetan Goats from Nagqu, Tibet. Animals (Basel) 2020; 10:ani10091599. [PMID: 32911823 PMCID: PMC7552128 DOI: 10.3390/ani10091599] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/28/2020] [Accepted: 09/04/2020] [Indexed: 12/18/2022] Open
Abstract
Simple Summary In the process of domestication, goats have undergone long-term artificial and natural selection, leading to differences among goat breeds and leaving different selection traces on the genome. However, the genetic components underlying high-altitude adaptation remain largely unknown. Here, we genotyped four goat breeds using the Illumina Caprine 50K single nucleotide polymorphism (SNP) Chip. One highland breed (Tibetan goat) compared with three lowland breeds (Huanghuai goat, Taihang goat and Xinjiang goat) to identify the molecular basis of high-altitude adaptation. So, we investigated selection signatures using the di statistic of four goat breeds and some genes in Tibetan goats related to high-altitude adaptation were identified. In addition, q-PCR validated the gene expression level in Tibetan goats and Huanghuai goats. This information may be valuable for the study of the genetic uniqueness of Tibetan goats and increased understanding of the hypoxic adaptation mechanism of Tibetan goats on the plateau. Abstract Tibetan goat is an ancient breed, which inhabits the adverse conditions of the plateaus in China. To investigate the role of selection in shaping its genomes, we genotyped Tibetan goats (Nagqu Prefecture, above 4500 m) and three lowland populations (Xinjiang goats, Taihang goats and Huanghuai goats). The result of PCA, neighbor-joining (N-J) tree and model-based clustering showed that the genetic structure between the Tibetan goat and the three lowland populations has significant difference. As demonstrated by the di statistic, we found that some genes were related to the high-altitude adaptation of Tibetan goats. Functional analysis revealed that these genes were enriched in the VEGF (vascular endothelial growth factor) signaling pathway and melanoma, suggesting that nine genes (FGF2, EGFR, AKT1, PTEN, MITF, ENPEP, SIRT6, KDR, and CDC42) might have important roles in the high-altitude adaptation of Nagqu Tibetan goats. We also found that the LEPR gene was under the strongest selection (di value = 16.70), and it could induce upregulation of the hypoxic ventilatory response. In addition, five genes (LEPR, LDB1, EGFR, NOX4 and FGF2) with high di values were analyzed using q-PCR. Among them, we found that LEPR, LDB1 and FGF2 exhibited higher expression in the lungs of the Tibetan goats; LEPR, EGFR and LDB1 exhibited higher expression in the hearts of the Huanghuai goat. Our results suggest that LEPR, LDB1, EGFR and FGF2 genes may be related to the high-altitude adaptation of the goats. These findings improve our understanding of the selection of the high-altitude adaptability of the Nagqu Tibetan goats and provide new theoretical knowledge for the conservation and utilization of germplasm resources.
Collapse
Affiliation(s)
- Meilin Jin
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (M.J.); (X.F.); (M.C.); (R.D.)
| | - Jian Lu
- National Animal Husbandry Service, Beijing 100193, China;
| | - Xiaojuan Fei
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (M.J.); (X.F.); (M.C.); (R.D.)
| | - Zengkui Lu
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China;
| | - Kai Quan
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou 450046, China;
| | - Yongbin Liu
- Inner Mongolia Academy of Animal Husbandry Science, Hohhot 010031, China;
| | - Mingxing Chu
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (M.J.); (X.F.); (M.C.); (R.D.)
| | - Ran Di
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (M.J.); (X.F.); (M.C.); (R.D.)
| | - Caihong Wei
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (M.J.); (X.F.); (M.C.); (R.D.)
- Correspondence: (C.W.); (H.W.)
| | - Huihua Wang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (M.J.); (X.F.); (M.C.); (R.D.)
- Correspondence: (C.W.); (H.W.)
| |
Collapse
|
13
|
Muckenthaler MU, Mairbäurl H, Gassmann M. Iron metabolism in high-altitude residents. J Appl Physiol (1985) 2020; 129:920-925. [PMID: 32853112 DOI: 10.1152/japplphysiol.00019.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Residents at high altitude cope with decreasing inspiratory oxygen partial pressure by stimulating erythropoiesis. The increase in hemoglobin levels requires high amounts of additional iron supplied from the diet. Here, we review available data on how iron metabolism adapts when living in a hypoxic environment. Our analysis reveals that long-term adaptation to high altitude enables healthy individuals to maintain their iron stores within the physiological range despite elevated requirements for erythropoiesis. However, in vulnerable populations with increased iron demand (e.g., pregnant women or exercising individuals), iron stores are less likely to be replenished quickly when living at high altitude. Future studies need to address whether different ethnicities have acquired genetic mechanisms to adapt to the elevated iron demand for erythropoiesis at high altitude.
Collapse
Affiliation(s)
- Martina U Muckenthaler
- Pediatric Oncology, Hematology & Immunology, University Hospital Heidelberg, Heidelberg, Molecular Medicine Partnership Unit, University of Heidelberg, Heidelberg, Germany.,Translational Lung Research Center Heidelberg, Member of the German Center for Lung Research, Heidelberg, Germany
| | - Heimo Mairbäurl
- Translational Lung Research Center Heidelberg, Member of the German Center for Lung Research, Heidelberg, Germany.,Translational Pneumology, University Hospital Heidelberg, Heidelberg, Germany
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, and Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.,Universidad Peruana Cayetano Heredia, Lima, Peru
| |
Collapse
|
14
|
Gassmann M, Mairbäurl H, Livshits L, Seide S, Hackbusch M, Malczyk M, Kraut S, Gassmann NN, Weissmann N, Muckenthaler MU. The increase in hemoglobin concentration with altitude varies among human populations. Ann N Y Acad Sci 2019; 1450:204-220. [PMID: 31257609 DOI: 10.1111/nyas.14136] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/02/2019] [Accepted: 05/16/2019] [Indexed: 02/06/2023]
Abstract
Decreased oxygen availability at high altitude requires physiological adjustments allowing for adequate tissue oxygenation. One such mechanism is a slow increase in the hemoglobin concentration ([Hb]) resulting in elevated [Hb] in high-altitude residents. Diagnosis of anemia at different altitudes requires reference values for [Hb]. Our aim was to establish such values based on published data of residents living at different altitudes by applying meta-analysis and multiple regressions. Results show that [Hb] is increased in all high-altitude residents. However, the magnitude of increase varies among the regions analyzed and among ethnic groups within a region. The highest increase was found in residents of the Andes (1 g/dL/1000 m), but this increment was smaller in all other regions of the world (0.6 g/dL/1000 m). While sufficient data exist for adult males and females showing that sex differences in [Hb] persist with altitude, data for infants, children, and pregnant women are incomplete preventing such analyses. Because WHO reference values were originally based on [Hb] of South American people, we conclude that individual reference values have to be defined for ethnic groups to reliably diagnose anemia and erythrocytosis in high-altitude residents. Future studies need to test their applicability for children of different ages and pregnant women.
Collapse
Affiliation(s)
- Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.,Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru
| | - Heimo Mairbäurl
- Translational Lung Research Center Heidelberg (TLRC), the German Center for Lung Research (DZL), Heidelberg, Germany
| | - Leonid Livshits
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Svenja Seide
- Institute of Medical Biometry and Informatics (IMBI), University Hospital Heidelberg, Heidelberg, Germany
| | - Matthes Hackbusch
- Institute of Medical Biometry and Informatics (IMBI), University Hospital Heidelberg, Heidelberg, Germany
| | - Monika Malczyk
- Excellence Cluster Cardiopulmonary System, Justus-Liebig-University Giessen, University of Giessen and Marburg Lung Center, German Center for Lung Research (DZL), Heidelberg, Germany
| | - Simone Kraut
- Excellence Cluster Cardiopulmonary System, Justus-Liebig-University Giessen, University of Giessen and Marburg Lung Center, German Center for Lung Research (DZL), Heidelberg, Germany
| | - Norina N Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Norbert Weissmann
- Excellence Cluster Cardiopulmonary System, Justus-Liebig-University Giessen, University of Giessen and Marburg Lung Center, German Center for Lung Research (DZL), Heidelberg, Germany
| | - Martina U Muckenthaler
- Pediatric Hematology, Oncology and Immunology, University Hospital Heidelberg, Molecular Medicine Partnership Unit, University of Heidelberg, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research, Heidelberg, Germany
| |
Collapse
|
15
|
Hilty MP, Merz TM, Hefti U, Ince C, Maggiorini M, Pichler Hefti J. Recruitment of non-perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m. J Physiol 2019; 597:2623-2638. [PMID: 30843200 DOI: 10.1113/jp277590] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/05/2019] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries. In the present study, we report that high altitude-induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance. Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude-related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis. The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success. ABSTRACT A high altitude (HA) stay is associated with an increase in sublingual capillary total vessel density (TVD), suggesting microvascular recruitment. We hypothesized that microvascular recruitment occurs independent of cardiac output changes, that it relies on haemodynamic changes within the microcirculation as opposed to structural changes and that microcirculatory function is related to individual performance at HA. In 41 healthy subjects, sublingual handheld vital microscopy and echocardiography were performed at sea level (SL), as well as at 6022 m (C2) and 7042 m (C3), during ascent to 7126 m within 21 days. Sublingual topical nitroglycerin was applied to measure microvascular reactivity and maximum recruitable TVD (TVDNG ). HA exposure decreased resting cardiac output, whereas TVD (mean ± SD) increased from 18.81 ± 3.92 to 20.92 ± 3.66 and 21.25 ± 2.27 mm mm-2 (P < 0.01). The difference between TVD and TVDNG was 2.28 ± 4.59 mm mm-2 at SL (P < 0.01) but remained undetectable at HA. Maximal TVDNG was observed at C3. Those who reached the summit (n = 15) demonstrated higher TVD at SL (P < 0.01), comparable to TVDNG in non-summiters (n = 21) at SL and in both groups at C2. Recruitment of sublingual capillary TVD to increase microcirculatory oxygen extraction capacity at HA was found to be an intrinsic mechanism of the microcirculation independent of cardiac output changes. Microvascular reactivity to topical nitroglycerin demonstrated that HA-related capillary recruitment is a functional response as opposed to a structural change. The performance of the vascular microcirculation needed to reach the summit was found to be associated with a higher TVD at SL and the ability to further increase TVDNG upon ascent to extreme altitude.
Collapse
Affiliation(s)
- Matthias Peter Hilty
- Intensive Care Unit, University Hospital of Zurich, Zurich, Switzerland.,Department of Intensive Care, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Tobias Michael Merz
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Cardiovascular Intensive Care Unit, Auckland City Hospital, Auckland, New Zealand
| | - Urs Hefti
- Swiss Sportclinic, Bern, Switzerland
| | - Can Ince
- Department of Intensive Care, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Marco Maggiorini
- Intensive Care Unit, University Hospital of Zurich, Zurich, Switzerland
| | - Jacqueline Pichler Hefti
- Department of Pulmonary Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| |
Collapse
|
16
|
Human Genetic Adaptation to High Altitude: Evidence from the Andes. Genes (Basel) 2019; 10:genes10020150. [PMID: 30781443 PMCID: PMC6410003 DOI: 10.3390/genes10020150] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/29/2019] [Accepted: 02/11/2019] [Indexed: 12/31/2022] Open
Abstract
Whether Andean populations are genetically adapted to high altitudes has long been of interest. Initial studies focused on physiological changes in the O₂ transport system that occur with acclimatization in newcomers and their comparison with those of long-resident Andeans. These as well as more recent studies indicate that Andeans have somewhat larger lung volumes, narrower alveolar to arterial O₂ gradients, slightly less hypoxic pulmonary vasoconstrictor response, greater uterine artery blood flow during pregnancy, and increased cardiac O2 utilization, which overall suggests greater efficiency of O₂ transfer and utilization. More recent single nucleotide polymorphism and whole-genome sequencing studies indicate that multiple gene regions have undergone recent positive selection in Andeans. These include genes involved in the regulation of vascular control, metabolic hemostasis, and erythropoiesis. However, fundamental questions remain regarding the functional links between these adaptive genomic signals and the unique physiological attributes of highland Andeans. Well-designed physiological and genome association studies are needed to address such questions. It will be especially important to incorporate the role of epigenetic processes (i.e.; non-sequence-based features of the genome) that are vital for transcriptional responses to hypoxia and are potentially heritable across generations. In short, further exploration of the interaction among genetic, epigenetic, and environmental factors in shaping patterns of adaptation to high altitude promises to improve the understanding of the mechanisms underlying human adaptive potential and clarify its implications for human health.
Collapse
|
17
|
Koester-Hegmann C, Bengoetxea H, Kosenkov D, Thiersch M, Haider T, Gassmann M, Schneider Gasser EM. High-Altitude Cognitive Impairment Is Prevented by Enriched Environment Including Exercise via VEGF Signaling. Front Cell Neurosci 2019; 12:532. [PMID: 30687018 PMCID: PMC6335396 DOI: 10.3389/fncel.2018.00532] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/24/2018] [Indexed: 01/17/2023] Open
Abstract
Exposure to hypobaric hypoxia at high altitude (above 2500 m asl) causes cognitive impairment, mostly attributed to changes in brain perfusion and consequently neuronal death. Enriched environment and voluntary exercise has been shown to improve cognitive function, to enhance brain microvasculature and neurogenesis, and to be neuroprotective. Here we show that high-altitude exposure (3540 m asl) of Long Evans rats during early adulthood (P48-P59) increases brain microvasculature and neurogenesis but impairs spatial and visual memory along with an increase in neuronal apoptosis. We tested whether enriched environment including a running wheel for voluntary exercise (EE) can prevent cognitive impairment at high-altitude and whether apoptosis is prevented. We found that EE retained spatial and visual memory at high altitude, and prevented neuronal apoptosis. Further, we tested whether vascular endothelial growth factor (VEGF) signaling is required for the EE-mediated recovery of spatial and visual memory and the reduction in apoptosis. Pharmacological inhibition of VEGF signaling by oral application of a tyrosine kinase inhibitor (Vandetanib) prevented the recovery of spatial and visual memory in animals housed in EE, along with an increase in apoptosis and a reduction in neurogenesis. Surprisingly, inhibition of VEGF signaling also caused impairment in spatial memory in EE-housed animals reared at low altitude, affecting mainly dentate gyrus microvasculature but not neurogenesis. We conclude that EE-mediated VEGF signaling is neuroprotective and essential for the maintenance of cognition and neurogenesis during high-altitude exposure, and for the maintenance of spatial memory at low altitude. Finally, our data also underlines the potential risk of cognitive impairment and disturbed high altitude adaption from the use of VEGF-signaling inhibitors for therapeutic purposes.
Collapse
Affiliation(s)
- Christina Koester-Hegmann
- Neuroprotection Group, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Harkaitz Bengoetxea
- Laboratory of Clinical and Experimental Neuroscience (LaNCE), Department of Neuroscience, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Bilbao, Spain
| | - Dmitry Kosenkov
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Markus Thiersch
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Thomas Haider
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.,Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru
| | - Edith M Schneider Gasser
- Neuroprotection Group, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Center for Neuroscience Zurich (ZNZ), Zurich, Switzerland
| |
Collapse
|
18
|
Puchwein-Schwepcke A, Grzybowski AK, Genzel-Boroviczény O, Nussbaum C. Effects of Prematurity on the Cutaneous Microcirculatory Network in the First Weeks of Life. Front Pediatr 2019; 7:198. [PMID: 31179253 PMCID: PMC6542985 DOI: 10.3389/fped.2019.00198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 04/29/2019] [Indexed: 12/26/2022] Open
Abstract
Background: Preterm infants are at increased risk for hypertension in adolescence. Microcirculatory dysfunction has been identified as an underlying cause for cardiovascular disease. Our goal was to document the development of the cutaneous microcirculation in preterm infants during the first weeks of life and to compare it to the situation in term infants at birth. Methods: In 20 preterm infants, microcirculatory parameters were obtained prospectively by Sidestream Dark Field (SDF) Imaging at the upper inner arm once a week until discharge or 37 weeks of gestational age. A single microcirculatory measurement was obtained in 30 term infants during the first 3 days of life. Videos were blinded and analyzed with the AVA software. Results: Microcirculatory parameters in preterm infants differ significantly from term infants with a lower vessel surface (VS), a lower percentage of large and medium but higher percentage of small vessels, a higher Functional Vessel Density (FVD), and a higher Microcirculatory Flow Index (MFI). In multivariable linear regression models we could demonstrate a statistically significant association between the dependent microcirculatory variables (VS, diameter distribution, MFI) and gestational age as independent predictor variable while adjusting for postnatal days of life. Looking at the longitudinal follow-up data of preterm infants by means of a multivariable mixed-effects linear regression model adjusting for clinical variables, there is a significant decrease in FVD with increasing postnatal age, however no other significant changes in microcirculatory parameters over time. Accordingly, comparing the microcirculatory parameters of near term former preterm infants with term born neonates, we could still find significant differences with a higher FVD, lower VS and differences in vessel diameters in the former premature group. Conclusion: Infants born prematurely exhibit distinct microcirculatory alterations compared to term neonates with gestational age at birth being associated with microvascular parameters. Interestingly, this premature vascular phenotype persists even close to corrected term age. In view of the known increased cardiovascular risk of former preterm infants, our observations might have important clinical impact. The factors governing the development of the microvascular network in preterm infants and the contribution of microcirculatory changes observed here to vascular pathology in later life need to be further investigated.
Collapse
Affiliation(s)
| | - Ann-Kristin Grzybowski
- Divsion of Neonatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Orsolya Genzel-Boroviczény
- Divsion of Neonatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Claudia Nussbaum
- Divsion of Neonatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| |
Collapse
|
19
|
González R, Urbano J, Solana MJ, Hervías M, Pita A, Pérez R, Álvarez R, Teigell E, Gil-Jaurena JM, Zamorano J, Sobrino A, López-Herce J. Microcirculatory Differences in Children With Congenital Heart Disease According to Cyanosis and Age. Front Pediatr 2019; 7:264. [PMID: 31312623 PMCID: PMC6613439 DOI: 10.3389/fped.2019.00264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 06/10/2019] [Indexed: 12/11/2022] Open
Abstract
Background: Congenital heart disease (CHD) is one of the main causes of morbidity and mortality in children. Microcirculatory changes in CHD patients have previously been investigated using a variety of techniques. Handheld videomicroscopy enables non-invasive direct visualization of the microcirculatory bed. The aim of our study was to determine if there are microcirculatory differences among CHD patients based on age and the presence of cyanosis. Methods: A prospective observational study was carried out. Patients with CHD undergoing corrective surgery were evaluated after anesthetic induction prior to surgery. Microcirculation was evaluated using sidestream dark field (SDF) imaging. Hemodynamics and respiratory, biochemical, and tissue perfusion parameters were analyzed. Results: A total of 30 patients were included, of whom 14 were classified as cyanotic and 16 as non-cyanotic. Cyanotic patients had a higher total vessel density (TVD) (p = 0.016), small vessel density (p = 0.004), and perfused small vessel density (p = 0.013), while their microvascular flow index (MFI) was lower (p = 0.013). After adjustment for age and PaO2, cyanotic patients showed increased TVD (p = 0.023), and small vessel density (p = 0.025) compared to non-cyanotic patients but there were no differences on the MFI. Age was directly correlated with total MFI (spearman's rho = 0.499, p = 0.005) and small vessel MFI (spearman's rho = 0.420, p = 0.021). After adjustment for the type of CHD (cyanotic vs. non-cyanotic) patients with MFI and small MFI vessels <3 were younger than those with values ≥3 (p = 0.033 and p = 0.037). Conclusions: SDF-based evaluation of microcirculation in CHD patients showed that patients with cyanotic defects had higher vascular density, as compared to patients with non-cyanotic defects. Younger patients were more likely to have a low MFI regardless of their type of CHD.
Collapse
Affiliation(s)
- Rafael González
- Service of Paediatric Intensive Care, Gregorio Marañón General University Hospital, Madrid, Spain.,Mother and Child Health and Development Network (REDSAMID), Madrid, Spain
| | - Javier Urbano
- Service of Paediatric Intensive Care, Gregorio Marañón General University Hospital, Madrid, Spain.,Mother and Child Health and Development Network (REDSAMID), Madrid, Spain.,Department of Paediatrics, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - María J Solana
- Service of Paediatric Intensive Care, Gregorio Marañón General University Hospital, Madrid, Spain.,Mother and Child Health and Development Network (REDSAMID), Madrid, Spain
| | - Mónica Hervías
- Paediatric Anaesthesia, Gregorio Marañón General University Hospital, Madrid, Spain
| | - Ana Pita
- Paediatric Cardiac Surgery, Gregorio Marañón General University Hospital, Madrid, Spain
| | - Rosario Pérez
- Paediatric Hemoperfusionist, Gregorio Marañón General University Hospital, Madrid, Spain
| | - Reyes Álvarez
- Paediatric Cardiology, Gregorio Marañón General University Hospital, Madrid, Spain
| | - Enrique Teigell
- Paediatric Anaesthesia, Gregorio Marañón General University Hospital, Madrid, Spain
| | | | - José Zamorano
- Paediatric Hemoperfusionist, Gregorio Marañón General University Hospital, Madrid, Spain
| | - Adolfo Sobrino
- Paediatric Cardiology, Gregorio Marañón General University Hospital, Madrid, Spain
| | - Jesús López-Herce
- Service of Paediatric Intensive Care, Gregorio Marañón General University Hospital, Madrid, Spain.,Mother and Child Health and Development Network (REDSAMID), Madrid, Spain.,Department of Paediatrics, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| |
Collapse
|
20
|
Erdem Ö, Ince C, Tibboel D, Kuiper JW. Assessing the Microcirculation With Handheld Vital Microscopy in Critically Ill Neonates and Children: Evolution of the Technique and Its Potential for Critical Care. Front Pediatr 2019; 7:273. [PMID: 31338353 PMCID: PMC6629784 DOI: 10.3389/fped.2019.00273] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 06/17/2019] [Indexed: 12/17/2022] Open
Abstract
Assuring adequate tissue oxygenation in the critically ill, but still developing child is challenging. Conventional hemodynamic monitoring techniques fall short in assessing tissue oxygenation as these are directed at the macrocirculation and indirect surrogates of tissue oxygenation. The introduction of handheld vital microscopy (HVM) has allowed for the direct visualization of the microcirculation and with this has offered insight into tissue oxygenation on a microcirculatory level. Since its introduction, technical improvements have been made to HVM, to both hardware and software, and guidelines have been developed through expert consensus on image assessment and analysis. Using HVM, the microcirculation of the skin, the buccal mucosa, and the sublingual mucosa of healthy and (critically) ill neonates and children have been visualized and investigated. Yet, integration of HVM in hemodynamic monitoring has been limited due to technical shortcomings. Only superficial microcirculatory beds can be visualized, inter-observer and intra-observer variabilities are not accounted for and image analysis happens offline and is semi-automated and time-consuming. More importantly, patients need to be cooperative or fully sedated to prevent pressure and movement artifacts, which is often not the case in children. Despite these shortcomings, observational research with HVM in neonates and children has revealed the following: (1) age-related developmental changes in the microcirculation, (2) loss of hemodynamic coherence, i.e., microcirculatory disturbances in the presence of a normal macrocirculation and, (3) microcirculatory disturbances which were independently associated with increased mortality risk. Although these observations underline the importance of microcirculatory monitoring, several steps have to be taken before integration in the decision process during critical care can happen. These steps include technological innovations to ease the use of HVM in the pediatric age group, measuring additional functional parameters of microvascular blood flow and integrated automated analysis software. As a next step, reference values for microcirculatory parameters need to be established, while also accounting for developmental changes. Finally, studies on microcirculatory guided therapies are necessary to assess whether the integration of microcirculatory monitoring will actually improve patient outcome. Nevertheless, HVM remains a promising, non-invasive tool to help physicians assure tissue oxygenation in the critically ill child.
Collapse
Affiliation(s)
- Özge Erdem
- Intensive Care and Department of Pediatric Surgery, Erasmus University Medical Center - Sophia Children's Hospital, Rotterdam, Netherlands
| | - Can Ince
- Department of Intensive Care, Erasmus University Medical Center, Rotterdam, Netherlands.,Department of Translational Physiology, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Dick Tibboel
- Intensive Care and Department of Pediatric Surgery, Erasmus University Medical Center - Sophia Children's Hospital, Rotterdam, Netherlands
| | - Jan Willem Kuiper
- Intensive Care and Department of Pediatric Surgery, Erasmus University Medical Center - Sophia Children's Hospital, Rotterdam, Netherlands
| |
Collapse
|
21
|
Ducsay CA, Goyal R, Pearce WJ, Wilson S, Hu XQ, Zhang L. Gestational Hypoxia and Developmental Plasticity. Physiol Rev 2018; 98:1241-1334. [PMID: 29717932 PMCID: PMC6088145 DOI: 10.1152/physrev.00043.2017] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.
Collapse
Affiliation(s)
- Charles A. Ducsay
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Ravi Goyal
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - William J. Pearce
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Sean Wilson
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Xiang-Qun Hu
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Lubo Zhang
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| |
Collapse
|
22
|
Ince C, Boerma EC, Cecconi M, De Backer D, Shapiro NI, Duranteau J, Pinsky MR, Artigas A, Teboul JL, Reiss IKM, Aldecoa C, Hutchings SD, Donati A, Maggiorini M, Taccone FS, Hernandez G, Payen D, Tibboel D, Martin DS, Zarbock A, Monnet X, Dubin A, Bakker J, Vincent JL, Scheeren TWL. Second consensus on the assessment of sublingual microcirculation in critically ill patients: results from a task force of the European Society of Intensive Care Medicine. Intensive Care Med 2018; 44:281-299. [DOI: 10.1007/s00134-018-5070-7] [Citation(s) in RCA: 219] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/17/2018] [Indexed: 12/17/2022]
|
23
|
Moore LG. Measuring high-altitude adaptation. J Appl Physiol (1985) 2017; 123:1371-1385. [PMID: 28860167 DOI: 10.1152/japplphysiol.00321.2017] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 08/15/2017] [Accepted: 08/15/2017] [Indexed: 12/12/2022] Open
Abstract
High altitudes (>8,000 ft or 2,500 m) provide an experiment of nature for measuring adaptation and the physiological processes involved. Studies conducted over the past ~25 years in Andeans, Tibetans, and, less often, Ethiopians show varied but distinct O2 transport traits from those of acclimatized newcomers, providing indirect evidence for genetic adaptation to high altitude. Short-term (acclimatization, developmental) and long-term (genetic) responses to high altitude exhibit a temporal gradient such that, although all influence O2 content, the latter also improve O2 delivery and metabolism. Much has been learned concerning the underlying physiological processes, but additional studies are needed on the regulation of blood flow and O2 utilization. Direct evidence of genetic adaptation comes from single-nucleotide polymorphism (SNP)-based genome scans and whole genome sequencing studies that have identified gene regions acted upon by natural selection. Efforts have begun to understand the connections between the two with Andean studies on the genetic factors raising uterine blood flow, fetal growth, and susceptibility to Chronic Mountain Sickness and Tibetan studies on genes serving to lower hemoglobin and pulmonary arterial pressure. Critical for future studies will be the selection of phenotypes with demonstrable effects on reproductive success, the calculation of actual fitness costs, and greater inclusion of women among the subjects being studied. The well-characterized nature of the O2 transport system, the presence of multiple long-resident populations, and relevance for understanding hypoxic disorders in all persons underscore the importance of understanding how evolutionary adaptation to high altitude has occurred.NEW & NOTEWORTHY Variation in O2 transport characteristics among Andean, Tibetan, and, when available, Ethiopian high-altitude residents supports the existence of genetic adaptations that improve the distribution of blood flow to vital organs and the efficiency of O2 utilization. Genome scans and whole genome sequencing studies implicate a broad range of gene regions. Future studies are needed using phenotypes of clear relevance for reproductive success for determining the mechanisms by which naturally selected genes are acting.
Collapse
Affiliation(s)
- Lorna G Moore
- Division of Reproductive Sciences, Department of Obstetrics & Gynecology, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado
| |
Collapse
|
24
|
Santos-Concejero J, Billaut F, Grobler L, Oliván J, Noakes TD, Tucker R. Brain oxygenation declines in elite Kenyan runners during a maximal interval training session. Eur J Appl Physiol 2017; 117:1017-1024. [PMID: 28321639 DOI: 10.1007/s00421-017-3590-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/13/2017] [Indexed: 11/29/2022]
Abstract
PURPOSE The purpose of this study was to characterise the cerebral oxygenation (Cox) response during a high-intensity interval training session in Kenyan runners, and to examine any relationship with running performance. METHODS 15 Kenyan runners completed a 5-km time trial (TT) and a Fatigue Training Test on a treadmill (repeated running bouts of 1-km at a pace 5% faster than their mean 5-km TT pace with a 30-s recovery until exhaustion). Changes in Cox were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxy-haemoglobin (Δ[O2Hb] and Δ[HHb]), tissue oxygenation index (TOI), and total hemoglobin index (nTHI). RESULTS The number of 1-km repetitions achieved by the participants was 5.5 ± 1.2 repetitions at a mean pace of 20.5 ± 0.7 km h-1. Δ[O2Hb] measured at the end of each running repetition declined progressively over the course of the trial (p = 0.01, ES = 4.59). Δ[HHb] increased during each running bout until the end of the Fatigue Training Test (p < 0.001; ES = 6.0). TOI decreased significantly from the beginning of the test (p = 0.013, ES = 1.83), whereas nTHI remained stable (ES = 0.08). The Cox decline in the Fatigue Training Test was negatively correlated with the speed at which the test was completed (p = 0.017; r = -0.61), suggesting that the best performers were able to defend their Cox better than those of lower running ability. CONCLUSIONS In conclusion, this study suggests that elite Kenyan runners cannot defend cerebral oxygenation when forced to exercise to their physiological limits. This emphasises the critical importance of pacing in their racing success.
Collapse
Affiliation(s)
- Jordan Santos-Concejero
- Department of Physical Education and Sport, Faculty of Physical Activity and Sport Sciences, University of the Basque Country UPV/EHU, Portal de Lasarte 71, 01007, Vitoria-Gasteiz, Spain. .,UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
| | - F Billaut
- Department of Kinesiology, University Laval, Quebec, Canada
| | - L Grobler
- Department of Sport Science, University of Stellenbosch, Stellenbosch, South Africa
| | - J Oliván
- Department of Physiology, European University of Madrid, Madrid, Spain
| | - T D Noakes
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - R Tucker
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.,School of Medicine, University of the Free State, Bloemfontein, South Africa
| |
Collapse
|
25
|
Kenchegowda D, Natale B, Lemus MA, Natale DR, Fisher SA. Inactivation of maternal Hif-1α at mid-pregnancy causes placental defects and deficits in oxygen delivery to the fetal organs under hypoxic stress. Dev Biol 2016; 422:171-185. [PMID: 27940158 DOI: 10.1016/j.ydbio.2016.12.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 12/02/2016] [Accepted: 12/06/2016] [Indexed: 11/29/2022]
Abstract
A critical transition occurs near mid-gestation of mammalian pregnancy. Prior to this transition, low concentrations of oxygen (hypoxia) signaling through Hypoxia Inducible Factor (HIF) functions as a morphogen for the placenta and fetal organs. Subsequently, functional coupling of the placenta and fetal cardiovascular system for oxygen (O2) transport is required to support the continued growth and development of the fetus. Here we tested the hypothesis that Hif-1α is required in maternal cells for placental morphogenesis and function. We used Tamoxifen-inducible Cre-Lox to inactivate Hif-1α in maternal tissues at E8.5 (MATcKO), and used ODD-Luciferase as a reporter of hypoxia in placenta and fetal tissues. MATcKO of Hif-1α reduced the number of uterine natural killer (uNK) cells and Tpbpa-positve trophoblast cells in the maternal decidua at E13.5 -15.5. There were dynamic changes in all three layers of E13.5-15.5 MATcKO placenta. Of note was the under-development of the labyrinth at E15.5 associated with reduced Ki67 and increased TUNEL staining consistent with reduced cell proliferation and increased apoptosis. Labyrinth defects were particularly evident in placentas connected to effectively HIF-1α heterozygous null embryos. MATcKO had no effect on basal ODD-Luciferase activity in fetal organs (heart, liver, brain) at any stage, but at E13.5-15.5 resulted in enhanced induction of the ODD-Luciferase hypoxia reporter when the dam's inspired O2 was reduced to 8% for 4 hours. MATcKO also slowed the growth after E13.5 of fetuses that were effectively heterozygous for Hif-1α, with most being non-viable at E15.5. The hearts of these E15.5 fetuses were abnormal with reduction in size, thickened epicardium and mesenchymal septum. We conclude that maternal HIF-1α is required for placentation including recruitment of uNK and trophoblast cells into the maternal decidua and other trophoblast cell behaviors. The placental defects render the fetus vulnerable to O2 deprivation after mid-gestation.
Collapse
Affiliation(s)
- Doreswamy Kenchegowda
- Department of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Bryony Natale
- Department of Reproductive Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Maria A Lemus
- Department of Reproductive Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - David R Natale
- Department of Reproductive Medicine, University of California San Diego, La Jolla, CA 92093, USA.
| | - Steven A Fisher
- Department of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| |
Collapse
|