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Abstract
Vascular contributions to cognitive impairment and dementia (VCID) is an all-encompassing term that describes cognitive impairment due to cerebrovascular origins. With the advancement of imaging and pathological studies, we now understand that VCID is often comorbid with Alzheimer disease. While researchers in the Alzheimer disease field have been working for years to establish and test blood-based biomarkers for Alzheimer disease diagnosis, prognosis, clinical therapy discovery, and early detection, blood-based biomarkers for VCID are in their infancy and also face challenges. VCID is heterogeneous, comprising many different pathological entities (ischemic, or hemorrhagic), and spatial and temporal differences (acute or chronic). This review highlights pathways that are aiding the search for sensitive and specific blood-based cerebrovascular dysfunction markers, describes promising candidates, and explains ongoing initiatives to discover blood-based VCID biomarkers.
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Affiliation(s)
- Kate E. Foley
- Stark Neurosciences Research Institute, Indiana University, Indianapolis IN, USA
- Department of Neurology, School of Medicine, Indiana University, Indianapolis IN, USA
| | - Donna M. Wilcock
- Stark Neurosciences Research Institute, Indiana University, Indianapolis IN, USA
- Department of Neurology, School of Medicine, Indiana University, Indianapolis IN, USA
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Han C, Zheng XX, Zhang WF. High altitude retinopathy: An overview and new insights. Travel Med Infect Dis 2024; 58:102689. [PMID: 38295966 DOI: 10.1016/j.tmaid.2024.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/30/2023] [Accepted: 01/15/2024] [Indexed: 02/04/2024]
Abstract
High altitude retinopathy (HAR) is a common ocular disorder that occurs on ascent to high altitude. There are many clinical symptoms, retinal vascular dilatation, retinal edema and hemorrhage are common. These usually do not or slightly affect vision; rarely, severe cases develop serious or permanent vision loss. At present, the research progress of HAR mainly focuses on hemodynamic changes, blood-retinal barrier damage, oxidative stress and inflammatory response. Although the related studies on HAR are limited, it shows that HAR still belongs to hypoxia, and hypobaric hypoxia plays an aggravating role in promoting the development of the disease. Various studies have demonstrated the correlation of HAR with acute mountain sickness (AMS) and high-altitude cerebral edema (HACE), so a deeper understanding of HAR is important. The slow ascent rates and ascent altitude are the key to preventing any altitude sickness. Research on traditional chinese medicine (TCM) and western medicine has been gradually carried out. Further exploration of the pathogenesis and prevention strategies of HAR will provide better guidance for doctors and high-altitude travelers.
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Affiliation(s)
- Cong Han
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
| | - Xing-Xing Zheng
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
| | - Wen-Fang Zhang
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
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Transcriptomic analysis of the cerebral hippocampal tissue in spontaneously hypertensive rats exposed to acute hypobaric hypoxia: associations with inflammation and energy metabolism. Sci Rep 2023; 13:3681. [PMID: 36878975 PMCID: PMC9988845 DOI: 10.1038/s41598-023-30682-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
We evaluated the effect of acute hypobaric hypoxia (AHH) on the hippocampal region of the brain in early-stage spontaneously hypertensive male rats. The rats were classified into a control (ground level; ~ 400 m altitude) group and an AHH experimental group placed in an animal hypobaric chamber at a simulated altitude of 5500 m for 24 h. RNA-Seq analysis of the brains and hippocampi showed that differentially expressed genes (DEGs) were primarily associated with ossification, fibrillar collagen trimer, and platelet-derived growth factor binding. The DEGs were classified into functional categories including general function prediction, translation, ribosomal structure and biogenesis, replication, recombination, and repair. Pathway enrichment analysis revealed that the DEGs were primarily associated with relaxin signaling, PI3K-Akt signaling, and amoebiasis pathways. Protein-protein interaction network analysis indicated that 48 DEGs were involved in both inflammation and energy metabolism. Further, we performed validation experiments to show that nine DEGs were closely associated with inflammation and energy metabolism, of which two (Vegfa and Angpt2) and seven (Acta2, Nfkbia, Col1a1, Edn1, Itga1, Ngfr, and Sgk1) genes showed up and downregulated expression, respectively. Collectively, these results indicated that inflammation and energy metabolism-associated gene expression in the hippocampus was altered in early-stage hypertension upon AHH exposure.
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Liu T, Liao XZ, Zhou MT. Ulinastatin alleviates traumatic brain injury by reducing endothelin-1. Transl Neurosci 2021; 12:1-8. [PMID: 33505713 PMCID: PMC7788573 DOI: 10.1515/tnsci-2021-0001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/21/2022] Open
Abstract
Background Brain edema is one of the major causes of fatality and disability associated with injury and neurosurgical procedures. The goal of this study was to evaluate the effect of ulinastatin (UTI), a protease inhibitor, on astrocytes in a rat model of traumatic brain injury (TBI). Methodology A rat model of TBI was established. Animals were randomly divided into 2 groups – one group was treated with normal saline and the second group was treated with UTI (50,000 U/kg). The brain water content and permeability of the blood–brain barrier were assessed in the two groups along with a sham group (no TBI). Expression of the glial fibrillary acidic protein, endthelin-1 (ET-1), vascular endothelial growth factor (VEGF), and matrix metalloproteinase 9 (MMP-9) were measured by immunohistochemistry and western blot. Effect of UTI on ERK and PI3K/AKT signaling pathways was measured by western blot. Results UTI significantly decreased the brain water content and extravasation of the Evans blue dye. This attenuation was associated with decreased activation of the astrocytes and ET-1. UTI treatment decreased ERK and Akt activation and inhibited the expression of pro-inflammatory VEGF and MMP-9. Conclusion UTI can alleviate brain edema resulting from TBI by inhibiting astrocyte activation and ET-1 production.
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Affiliation(s)
- Ting Liu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Xing-Zhi Liao
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Mai-Tao Zhou
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
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Baertschi M, Dayhaw-Barker P, Flammer J. The effect of hypoxia on intra-ocular, mean arterial, retinal venous and ocular perfusion pressures. Clin Hemorheol Microcirc 2017; 63:293-303. [PMID: 26639768 DOI: 10.3233/ch-152025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
INTRODUCTION High altitude hypoxia is linked to decreased blood oxygen saturation with a related increase of Endothelin-1 (ET-1) blood plasma levels. As a consequence of such elevated ET-1 levels, alterations of retinal venous and ocular perfusion pressures are suspected. PURPOSE To measure the effect of hypoxia on intra-ocular pressure, mean arterial pressure, retinal venous pressure and to calculate ocular perfusion pressure. METHOD An experimental, prospective cohort study with 33 healthy subjects was conducted in which the subjects were confronted with long-term (days) environmental hypoxia at high altitudes. Mean arterial pressure, arterial blood oxygen saturation, intra-ocular pressure, retinal venous and ocular perfusion pressure were measured at 300 m/1'000 ft (baseline), 4200 m/13'800 ft and 6000 m/19'700 ft above sea level. RESULTS Arterial oxygen saturation (-13.06% ± 4.69, p = < 0.001; -23.46% ± 5.7,p = < 0.001), retinal venous pressure (+7.16 m Hg±8.2, p = < 0.001;+9.9 mm Hg±8.5, p = < 0.001) and ocular perfusion pressure (-8.49 mm Hg±10.6, p = < 0.001; -6.02 mm hg±11.2, p = 0.006) changed significantly from baseline at both high altitude of 4200 and 6000 m. Intra-ocular pressure did not change significantly at all altitudes (+1.16 mm Hg±4.5, p = 0.227; +0.84 mm Hg±4.8, p = 0.286) and mean arterial pressure changed significantly only at an altitude of 6000 m (+3,8 mm Hg±21.1, p = 0.005) from baseline. CONCLUSION As hypoxia increases with higher altitude, arterial oxygen saturation and ocular perfusion pressure decreased, retinal venous pressure increased, intra-ocular pressure remains stable and mean arterial pressure was elevated only at 6000 m.
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Affiliation(s)
- M Baertschi
- University of Basel, Department of Ophthalmology, Basel, Switzerland.,SALUS University, Philadelphia, PA, USA.,Eyeness AG, Hirschengraben, Bern, Switzerland
| | | | - J Flammer
- University of Basel, Department of Ophthalmology, Basel, Switzerland
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Neumann T, Baertschi M, Vilser W, Drinda S, Franz M, Brückmann A, Wolf G, Jung C. Retinal vessel regulation at high altitudes1. Clin Hemorheol Microcirc 2016; 63:281-92. [DOI: 10.3233/ch-162041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Thomas Neumann
- Department of Internal Medicine III, Jena University Hospital, Jena, Germany
| | - Michael Baertschi
- Department of Ophthalmology, University of Basel, Switzerland
- Eyeness AG, Bern, Switzerland
| | | | | | - Marcus Franz
- Department of Internal Medicine I, Jena University Hospital, Jena, Germany
| | | | - Gunter Wolf
- Department of Internal Medicine III, Jena University Hospital, Jena, Germany
| | - Christian Jung
- University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Medical Faculty, Division of Cardiology, Pulmonology and Vascular Medicine, Düsseldorf, Germany
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Zhou Q, Yang S, Luo Y, Qi Y, Yan Z, Shi Z, Fan Y. A randomly-controlled study on the cardiac function at the early stage of return to the plains after short-term exposure to high altitude. PLoS One 2012; 7:e31097. [PMID: 22363556 PMCID: PMC3281922 DOI: 10.1371/journal.pone.0031097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 01/02/2012] [Indexed: 11/18/2022] Open
Abstract
High altitude acclimatization and adaptation mechanisms have been well clarified, however, high altitude de-adaptation mechanism remains unclear. In this study, we conducted a controlled study on cardiac functions in 96 healthy young male who rapidly entered the high altitude (3700 m) and returned to the plains (1500 m) after 50 days. Ninety eight healthy male who remained at low altitude were recruited as control group. The mean pulmonary arterial pressure (mPAP), left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), cardiac function index (Tei index) were tested. Levels of serum creatine kinase isoform MB (CK-MB), lactate dehydrogenase isoenzyme-1 (LDH-1), endothelin-1 (ET-1), nitrogen oxide (NO), serum hypoxia-inducible factor-1α (HIF-1α), 8-iso-prostaglandin F2α (8-iso PGF2α), superoxide dismutase (SOD) and malonaldehyde (MDA) were measured at an altitude of 3700 m and 1500 m respectively. The results showed that after short-term exposure to high altitude mPAP and Tei index increased significantly, while LVEF and LVFS decreased significantly. These changes were positively correlated with altitude. On the 15th day after the subjects returned to low altitude, mPAP, LVEF and LVFS levels returned to the same level as those of the control subjects, but the Tei index in the returned subjects was still significantly higher than that in the control subjects (P<0.01). We also found that changes in Tei index was positively correlated with mPAP, ET-1, HIF-1α and 8-iso PGF2α levels, and negatively correlated with the level of NO, LVEF, LVFS, CK-MB and LDH-1. These findings suggest that cardiac function de-adapts when returning to the plains after short-term exposure to high altitude and the function recovery takes a relatively long time.
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Affiliation(s)
- Qiquan Zhou
- Department of High Altitude Diseases, College of High Altitude Military Medicine, Third Military Medical University, Chongqing, China.
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Ainslie PN, Ogoh S. Regulation of cerebral blood flow in mammals during chronic hypoxia: a matter of balance. Exp Physiol 2009; 95:251-62. [PMID: 19617269 DOI: 10.1113/expphysiol.2008.045575] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Respiratory-induced changes in the partial pressures of arterial carbon dioxide (PaCO2) and oxygen (PaO2) play a major role in cerebral blood flow (CBF) regulation. Elevations in PaCO2 (hypercapnia) lead to vasodilatation and increases in CBF, whereas reductions in PaCO2 (hypocapnia) lead to vasoconstriction and decreases in CBF. A fall in PaO2 (hypoxia) below a certain threshold (<40-45 mmHg) also produces cerebral vasodilatation. Upon initial exposure to hypoxia, CBF is elevated via a greater relative degree of hypoxia compared with hypocapnia. At this point, hypoxia-induced elevations in blood pressure and loss of cerebral autoregulation, stimulation of neuronal pathways, angiogenesis, release of adenosine, endothelium-derived NO and a variety of autocoids and cytokines are additional factors acting to increase CBF. Following 2-3 days, however, the process of ventilatory acclimatization results in a progressive rise in ventilation, which increases PaO2 and reduces PaCO2, collectively acting to attenuate the initial rise in CBF. Other factors acting to lower CBF include elevations in haematocrit, sympathetic nerve activity and local and endothelium-derived vasoconstrictors. Hypoxia-induced alterations of cerebrovascular reactivity, autoregulation and pulmonary vascular tone may also affect CBF. Thus, the extent of change in CBF during exposure to hypoxia is dependent on the balance between the myriad of vasodilators and constrictors derived from the endothelium, neuronal innervations and perfusion pressure. This review examines the extent and mechanisms by which hypoxia regulates CBF. Particular focus will be given to the marked influence of hypoxia associated with exposure to high altitude and chronic lung disease. The associated implications of these hypoxia-induced integrative alterations for the regulation of CBF are discussed, and future avenues for research are proposed.
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Affiliation(s)
- Philip N Ainslie
- Department of Human Kinetics, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna V1V 1V7, Canada.
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Gomez A, Moreno M, Baldrich R, Hernández A. Endothelin-1 Molecular Ribonucleic Acid Expression in Pulmonary Hypertensive and Nonhypertensive Chickens. Poult Sci 2008; 87:1395-401. [DOI: 10.3382/ps.2007-00410] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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10
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Corticotropin-releasing hormone receptor 1 coexists with endothelin-1 and modulates its mRNA expression and release in rat paraventricular nucleus during hypoxia. Neuroscience 2008; 152:1006-14. [DOI: 10.1016/j.neuroscience.2007.11.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 11/16/2007] [Accepted: 11/19/2007] [Indexed: 12/21/2022]
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11
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Palmer LA, Doctor A, Chhabra P, Sheram ML, Laubach VE, Karlinsey MZ, Forbes MS, Macdonald T, Gaston B. S-nitrosothiols signal hypoxia-mimetic vascular pathology. J Clin Invest 2007; 117:2592-601. [PMID: 17786245 PMCID: PMC1952618 DOI: 10.1172/jci29444] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 05/24/2007] [Indexed: 12/27/2022] Open
Abstract
NO transfer reactions between protein and peptide cysteines have been proposed to represent regulated signaling processes. We used the pharmaceutical antioxidant N-acetylcysteine (NAC) as a bait reactant to measure NO transfer reactions in blood and to study the vascular effects of these reactions in vivo. NAC was converted to S-nitroso-N-acetylcysteine (SNOAC), decreasing erythrocytic S-nitrosothiol content, both during whole-blood deoxygenation ex vivo and during a 3-week protocol in which mice received high-dose NAC in vivo. Strikingly, the NAC-treated mice developed pulmonary arterial hypertension (PAH) that mimicked the effects of chronic hypoxia. Moreover, systemic SNOAC administration recapitulated effects of both NAC and hypoxia. eNOS-deficient mice were protected from the effects of NAC but not SNOAC, suggesting that conversion of NAC to SNOAC was necessary for the development of PAH. These data reveal an unanticipated adverse effect of chronic NAC administration and introduce a new animal model of PAH. Moreover, evidence that conversion of NAC to SNOAC during blood deoxygenation is necessary for the development of PAH in this model challenges conventional views of oxygen sensing and of NO signaling.
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Affiliation(s)
- Lisa A. Palmer
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Allan Doctor
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Preeti Chhabra
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Mary Lynn Sheram
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Victor E. Laubach
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Molly Z. Karlinsey
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Michael S. Forbes
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Timothy Macdonald
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Benjamin Gaston
- Department of Pediatrics and
Department of Surgery, University of Virginia School of Medicine, and
Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
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12
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Gomez AP, Moreno MJ, Iglesias A, Coral PX, Hernández A. Endothelin 1, its Endothelin Type A Receptor, Connective Tissue Growth Factor, Platelet-Derived Growth Factor, and Adrenomedullin Expression in Lungs of Pulmonary Hypertensive and Nonhypertensive Chickens. Poult Sci 2007; 86:909-16. [PMID: 17435025 DOI: 10.1093/ps/86.5.909] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Twenty-four 1-d-old broilers were distributed in 2 groups, pulmonary hypertensive broilers (PHB) and pulmonary nonhypertensive broilers (NPHB), to estimate possible differences between them in the expression of endothelin 1 (ET-1) and its type A receptor, connective tissue growth factor, platelet-derived growth factor, and adrenomedullin expression in the lungs. For this purpose, total RNA extraction and real-time PCR analysis were used. Endothelin 1 mRNA levels in the lungs of PHB were significantly higher than the corresponding level in NPHB (P < 0.001). In contrast, the opposite was true for ET-1 type A receptor mRNA levels (P < 0.001). Connective tissue growth factor mRNA levels in the lungs of PHB were significantly higher than in the lungs of NPHB (P < 0.01). However, no differences were encountered between the 2 groups of broilers in platelet-derived growth factor mRNA expression (P > 0.05). Adrenomedullin mRNA levels in the lungs of PHB were significantly higher than in NPHB (P < 0.01). It has been demonstrated for the first time that ET-1, connective tissue growth factor, and adrenomedullin are upregulated in the lungs of PHB. Furthermore, it is suggested that these peptides may play a major role in pulmonary hypertension pathophysiology. Present data might provide clues for future research directions such as genetic selection and therapeutic intervention to revert the process of pulmonary vasoconstriction and vascular remodeling. Major research goals could be to find endothelium-derived factors that probably trigger endothelial dysfunction, as well as possible interactions with already identified molecules which also intervene in the pulmonary response to hypoxia.
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Affiliation(s)
- A P Gomez
- Facultad de Medicina Veterinaria y de Zootecnia, Universidad Nacional de Colombia, Bogotá, DC (1), Colombia
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13
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Jansen GFA, Krins A, Basnyat B, Odoom JA, Ince C. Role of the altitude level on cerebral autoregulation in residents at high altitude. J Appl Physiol (1985) 2007; 103:518-23. [PMID: 17463295 DOI: 10.1152/japplphysiol.01429.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebral autoregulation is impaired in Himalayan high-altitude residents who live above 4,200 m. This study was undertaken to determine the altitude at which this impairment of autoregulation occurs. A second aim of the study was to test the hypothesis that administration of oxygen can reverse this impairment in autoregulation at high altitudes. In four groups of 10 Himalayan high-altitude dwellers residing at 1,330, 2,650, 3,440, and 4,243 m, arterial oxygen saturation (Sa(O(2))), blood pressure, and middle cerebral artery blood velocity were monitored during infusion of phenylephrine to determine static cerebral autoregulation. On the basis of these measurements, the cerebral autoregulation index (AI) was calculated. Normally, AI is between zero and 1. AI of 0 implies absent autoregulation, and AI of 1 implies intact autoregulation. At 1,330 m (Sa(O(2)) = 97%), 2,650 m (Sa(O(2)) = 96%), and 3,440 m (Sa(O(2)) = 93%), AI values (mean +/- SD) were, respectively, 0.63 +/- 0.27, 0.57 +/- 0.22, and 0.57 +/- 0.15. At 4,243 m (Sa(O(2)) = 88%), AI was 0.22 +/- 0.18 (P < 0.0005, compared with AI at the lower altitudes) and increased to 0.49 +/- 0.23 (P = 0.008, paired t-test) when oxygen was administered (Sa(O(2)) = 98%). In conclusion, high-altitude residents living at 4,243 m have almost total loss of cerebral autoregulation, which improved during oxygen administration. Those people living at 3,440 m and lower have still functioning cerebral autoregulation. This study showed that the altitude region between 3,440 and 4,243 m, marked by Sa(O(2)) in the high-altitude dwellers of 93% and 88%, is a transitional zone, above which cerebral autoregulation becomes critically impaired.
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Affiliation(s)
- Gerard F A Jansen
- Dept. of Anesthesiology, H1-Z, Academic Medical Centre, Univ. of Amsterdam, The Netherlands.
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Just S, Arndt K, Weiser T, Doods H. Pathophysiology of migraine: A role for neuropeptides. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.ddmec.2006.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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15
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Barer GR, Fairlie J, Slade JY, Ahmed S, Laude EA, Emery CJ, Thwaites-Bee D, Oakley AE, Barer DH, Kalaria RN. Effects of NOS inhibition on the cardiopulmonary system and brain microvascular markers after intermittent hypoxia in rats. Brain Res 2006; 1098:196-203. [PMID: 16793027 DOI: 10.1016/j.brainres.2006.04.098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 04/13/2006] [Accepted: 04/17/2006] [Indexed: 01/30/2023]
Abstract
We previously demonstrated that rats subjected to intermittent hypoxia (IH) by exposure to 10% O(2) for 4 h daily for 56 days in a normobaric chamber, developed pulmonary hypertension, right ventricular hypertrophy and wall-thickening in pulmonary arterioles, compared with normoxic (N) controls. These changes were greater in rats subjected to continuous hypoxia (CH breathing 10% O(2) for 56 days). Cerebral angiogenesis was demonstrated by immunostaining with glucose transporter 1 (GLUT1) antibody, in viable vessels, in CH and to a lesser degree in IH. In this study, adult Wistar rats were subjected to the same hypoxic regimes and given the nitric oxide synthase (NOS) inhibitor N(6)-nitro-L-arginine methyl ester (L-NAME) in drinking water (NLN, IHLN and CHLN regimes) to induce hypertension. There was significant systemic hypertension in NLN and IHLN rats, compared with N and IH, but surprisingly not in CHLN compared with CH. Hematocrit rose in all hypoxic groups (up to 79% in CHLN). There was no significant pulmonary hypertension in IHLN versus NLN rats, although there was asymmetric wall thickening in pulmonary arterioles. Cerebral GLUT1 immunoreactivity increased with L-NAME, with or without hypoxia, especially in CHLN rats, but conspicuously there was no evidence of angiogenesis in brains of IHLN compared with NLN rats. NOS blockade may attenuate the cerebral and pulmonary vascular changes of IH while augmenting cerebral angiogenesis in continuous hypoxia. However, whether cerebral effects are due to systemic hypertension or changes in cerebral nitric oxide production needs to be evaluated.
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Affiliation(s)
- G R Barer
- Wolfson Research Centre, Institute for Ageing and Health, Newcastle General Hospital, Westgate Road, Newcastle upon Tyne NE4 6BE, UK.
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Wu CY, Kaur C, Lu J, Cao Q, Guo CH, Zhou Y, Sivakumar V, Ling EA. Transient expression of endothelins in the amoeboid microglial cells in the developing rat brain. Glia 2006; 54:513-25. [PMID: 16897776 DOI: 10.1002/glia.20402] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Amoeboid microglial cells (AMC) which transiently exist in the corpus callosum in the postnatal rat brain expressed endothelins (ETs), specifically endothelin-1 (ET-1) and ET3 as revealed by real time RT-PCR. ET immunoreactive AMC occurred in large numbers at birth, but were progressively reduced with age and were undetected in 14 days. In rats subjected to hypoxia exposure, ET immunoexpression in AMC was reduced but the incidence of apoptotic cells was not increased when compared with the control suggesting that this was due to its downregulation that may help regulate the constriction of blood vessels bearing ET-A receptor. AMC were endowed ET-B receptor indicating that ET released by the cells may also act via an autocrine manner. In microglia activated by lipopolysaccharide (LPS), ET-1 mNA expression coupled with that of monocyte chemoattractant protein (MCP-1) and stromal derived factor-1 (SDF-1) was markedly increased; ET-3 mRNA, however, remained unaffected. AMC exposed to oxygen glucose deprivation (OGD) in vitro resulted in increase in both ET-1 and ET-3 mRNA expression. It is suggested that the downregulated ETs expression in vivo of AMC subjected to hypoxia as opposed to its upregulated expression in vitro may be due to the complexity of the brain tissue. Furthermore, the differential ET-1 and ET-3 mRNA expression in LPS and OGD treatments may be due to different signaling pathways independently regulating the two isoforms. The present novel finding has added microglia as a new cellular source of ET that may take part in multiple functions including regulating vascular constriction and chemokines release.
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MESH Headings
- Animals
- Animals, Newborn
- Brain/embryology
- Brain/growth & development
- Brain/ultrastructure
- Cell Differentiation/physiology
- Cell Movement/physiology
- Cells, Cultured
- Down-Regulation/physiology
- Endothelin-1/genetics
- Endothelin-1/metabolism
- Endothelin-3/genetics
- Endothelin-3/metabolism
- Endothelins/genetics
- Endothelins/metabolism
- Female
- Gene Expression Regulation, Developmental/physiology
- Hypoxia-Ischemia, Brain/genetics
- Hypoxia-Ischemia, Brain/metabolism
- Hypoxia-Ischemia, Brain/physiopathology
- Male
- Microcirculation/embryology
- Microcirculation/growth & development
- Microcirculation/metabolism
- Microglia/metabolism
- Microglia/ultrastructure
- Microscopy, Electron, Transmission
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Endothelin/metabolism
- Vasoconstriction/physiology
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Affiliation(s)
- Chun-Yun Wu
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Severinghaus JW. Sightings. High Alt Med Biol 2005. [DOI: 10.1089/ham.2005.6.198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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