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Zhou G, Chen J, Wu C, Jiang P, Wang Y, Zhang Y, Jiang Y, Li X. Deciphering the Protein, Modular Connections and Precision Medicine for Heart Failure With Preserved Ejection Fraction and Hypertension Based on TMT Quantitative Proteomics and Molecular Docking. Front Physiol 2021; 12:607089. [PMID: 34721049 PMCID: PMC8552070 DOI: 10.3389/fphys.2021.607089] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 09/23/2021] [Indexed: 12/16/2022] Open
Abstract
Background: Exploring the potential biological relationships between heart failure with preserved ejection fraction (HFpEF) and concomitant diseases has been the focus of many studies for the establishment of personalized therapies. Hypertension (HTN) is the most common concomitant disease in HFpEF patients, but the functional connections between HFpEF and HTN are still not fully understood and effective treatment strategies are still lacking. Methods: In this study, tandem mass tag (TMT) quantitative proteomics was used to identify disease-related proteins and construct disease-related networks. Furthermore, functional enrichment analysis of overlapping network modules was used to determine the functional similarities between HFpEF and HTN. Molecular docking and module analyses were combined to identify therapeutic targets for HFpEF and HTN. Results: Seven common differentially expressed proteins (co-DEPs) and eight overlapping modules were identified in HFpEF and HTN. The common biological processes between HFpEF and HTN were mainly related to energy metabolism. Myocardial contraction, energy metabolism, apoptosis, oxidative stress, immune response, and cardiac hypertrophy were all closely associated with HFpEF and HTN. Epinephrine, sulfadimethoxine, chloroform, and prednisolone acetate were best matched with the co-DEPs by molecular docking analyses. Conclusion: Myocardial contraction, energy metabolism, apoptosis, oxidative stress, immune response, and cardiac hypertrophy were the main functional connections between HFpEF and HTN. Epinephrine, sulfadimethoxine, chloroform, and prednisolone acetate could potentially be effective for the treatment of HTN and HFpEF.
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Affiliation(s)
- Guofeng Zhou
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Jiye Chen
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Chuanhong Wu
- The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao University, Qingdao, China
| | - Ping Jiang
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Yongcheng Wang
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Yongjian Zhang
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Yuehua Jiang
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xiao Li
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
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Zou L, Yuan H, Liu Q, Lu C, Wang L. Potential protective effects of bilirubin following the treatment of neonatal hypoxic-ischemic encephalopathy with hypothermia therapy. Biosci Rep 2019; 39:BSR20182332. [PMID: 31101685 DOI: 10.1042/BSR20182332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 04/21/2019] [Accepted: 05/07/2019] [Indexed: 12/02/2022] Open
Abstract
Background: Therapeutic hypothermia (TH) is the standard therapy for hypoxic-ischemic encephalopathy (HIE) and is associated with a wide range of physiological changes. Objective: We re-evaluated the effects of HIE and TH on bilirubin measurements following HIE in a center involved in the China cooling randomized controlled trial (RCT). Methods: Serial serum bilirubin concentrations measured during the first week of life were compared among the HIE + NT (normothermia) group, HIE + TH treatment group and control group (without HIE). Survivors of HIE were followed and assessed at approximately 2 years of age, and the results were correlated with peak bilirubin levels during the first week of life. Results: One hundred and thirty-eight infants were available for analysis. Significantly lower bilirubin levels were recorded in the HIE + NT group than in the controls (P<0.05). Significant differences were not observed among the patients in the HIE + NT group (mild to severe) or between the HIE + TH group and the HIE + NT group at any time point (P>0.05). The peak serum bilirubin concentrations recorded at 96 h of age showed a good correlation with the results of the Bayley Scales of Infant and Toddler Development, third edition (BSID-III) (P=0.02). Conclusion: Bilirubin potentially exerts a neuroprotective effect during the first week of life, and low temperature does not affect the possible antioxidant function of bilirubin during TH following HIE.
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Kuter N, Aysit-Altuncu N, Ozturk G, Ozek E. The Neuroprotective Effects of Hypothermia on Bilirubin-Induced Neurotoxicity in vitro. Neonatology 2018; 113:360-365. [PMID: 29510380 DOI: 10.1159/000487221] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/27/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND In high-risk newborns indirect hyperbilirubinemia can lead to acute bilirubin encephalopathy and kernicterus. Despite the current therapeutic modalities, preventing or reversing the neurotoxicity cannot be achieved in all infants. OBJECTIVE To investigate the neuroprotective effects of hypothermia on bilirubin-induced toxicity in primary mouse neuronal cell cultures. METHODS Hippocampal cell cultures, isolated from newborn mouse brains, were incubated with unconjugated bilirubin (UCB) at 3 days in vitro (DIV) and immediately exposed to varying degrees of hypothermia. Neuronal viability and mitochondrial health were compared between the normothermia (37°C), mild (34°C), moderate (32°C) and severe (29°C) hypothermia groups. Confocal microscopy and fluorescent dyes (propidium iodide and JC-1) were used for cell evaluation. To determine the late effects of hypothermia, the cultures were also examined at 7 DIV after returning to normothermic conditions. RESULTS Induction of any degree of hypothermia increased the neuronal survival after 24 h of UCB treatment. Neuronal death rate and mitochondrial membrane potential loss were lowest in the neurons exposed to moderate hypothermia. We also observed that mild to moderate hypothermia had late protective effects on neuronal cell viability, whereas deep hypothermia did not improve neuronal survival. CONCLUSIONS We conclude that hypothermia reduces the cell death induced by bilirubin toxicity in neuronal cells. Although moderate hypothermia has a better outcome than mild hypothermia, deep hypothermia as low as 29°C has adverse effects on neuronal cell viability.
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Affiliation(s)
- Nazli Kuter
- Department of Pediatrics, School of Medicine, Marmara University, Istanbul, Turkey
| | - Nese Aysit-Altuncu
- Department of Physiology, School of Medicine, Istanbul, Turkey.,Regenerative and Restorative Medicine Research Center (REMER), Istanbul, Turkey
| | - Gurkan Ozturk
- Regenerative and Restorative Medicine Research Center (REMER), Istanbul, Turkey.,Department of Physiology, International School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| | - Eren Ozek
- Division of Neonatology, Department of Pediatrics, School of Medicine, Marmara University, Istanbul, Turkey
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Specq ML, Bourgoin-Heck M, Samson N, Corbin F, Gestreau C, Richer M, Kadhim H, Praud JP. Moderate Hyperbilirubinemia Alters Neonatal Cardiorespiratory Control and Induces Inflammation in the Nucleus Tractus Solitarius. Front Physiol 2016; 7:437. [PMID: 27746740 PMCID: PMC5043013 DOI: 10.3389/fphys.2016.00437] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 09/14/2016] [Indexed: 11/29/2022] Open
Abstract
Hyperbilirubinemia (HB) occurs in 90% of preterm newborns. Moderate HB can induce acute neurological disorders while severe HB has been linked to a higher incidence of apneas of prematurity. The present study aimed to test the hypothesis that even moderate HB disrupts cardiorespiratory control in preterm lambs. Two groups of preterm lambs (born 14 days prior to term), namely control (n = 6) and HB (n = 5), were studied. At day 5 of life, moderate HB (150–250 μmol/L) was induced during 17 h in the HB group after which cardiorespiratory control as well as laryngeal and pulmonary chemoreflexes were assessed during baseline recordings and during hypoxia. Recordings were repeated 72 h after HB induction, just before euthanasia. In addition, neuropathological studies were performed to investigate for cerebral bilirubin deposition as well as for signs of glial reactivity in brainstem structures involved in cardiorespiratory control. Results revealed that sustained and moderate HB: (i) decreased baseline respiratory rate and increased the time spent in apnea; (ii) blunted the cardiorespiratory inhibition normally observed during both laryngeal and pulmonary chemoreflexes; and (iii) increased heart rate in response to acute hypoxia. These acute physiological changes were concurrent with an activation of Alzheimer type II astrocytes throughout the brain, including the brainstem. Concomitantly, bilirubin deposits were observed in the leptomeninges, but not in brain parenchyma. While most cardiorespiratory alterations returned to normal 72 h after HB normalization, the expression of glial fibrillary acid protein (GFAP) and ionized calcium binding adaptor molecule 1 (Iba1) was still increased within the nucleus tractus solitarius. In conclusion, moderate and sustained HB in preterm lambs induced cardiorespiratory alterations, the latter of which were associated with neurohistopathological changes. These changes are indicative of an inflammatory response in the brainstem neuroanatomical substrates involved in cardiorespiratory control.
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Affiliation(s)
- Marie-Laure Specq
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology - Physiology, Université de Sherbrooke Sherbrooke, QC, Canada
| | - Mélisande Bourgoin-Heck
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology - Physiology, Université de Sherbrooke Sherbrooke, QC, Canada
| | - Nathalie Samson
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology - Physiology, Université de Sherbrooke Sherbrooke, QC, Canada
| | - François Corbin
- Department of Biochemistry, Université de Sherbrooke Sherbrooke, QC, Canada
| | | | - Maxime Richer
- Department of Pathology, Université de Sherbrooke Sherbrooke, QC, Canada
| | - Hazim Kadhim
- Neuropathology Unit and Reference Center for Neuro-Muscular Pathology, Brugmann University Hospital and Childrens' Hospital (CHU Brugmann - HUDERF), Université Libre de Bruxelles Brussels, Belgium
| | - Jean-Paul Praud
- Neonatal Respiratory Research Unit, Departments of Pediatrics and Pharmacology - Physiology, Université de Sherbrooke Sherbrooke, QC, Canada
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Bourgoin-Heck M, Specq ML, Samson N, Nadeau C, Prodel M, Corbin F, Praud JP. Effects of Moderate Hyperbilirubinemia on Nutritive Swallowing and Swallowing-Breathing Coordination in Preterm Lambs. Neonatology 2015; 108:42-8. [PMID: 25968232 DOI: 10.1159/000381205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 02/19/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Hyperbilirubinemia (HB) occurs in 90% of preterm newborns. HB induces acute neurological disorders (somnolence, abnormal tone, feeding difficulties, auditory dysfunction) and alterations in respiratory control. These findings suggest brainstem neurotoxicity that could also affect swallowing centers. OBJECTIVE To test the hypothesis that HB impairs nutritive swallowing (NS) and swallowing-breathing coordination. METHODS Two groups of preterm lambs (born 14 days prior to term), namely control (n = 6) and HB (n = 5), were studied. On day 5 of life (D0), moderate HB (150-250 µmol/l) was induced during 17 h in the HB group. Swallowing was assessed via recording of pharyngeal pressure and respiration by respiratory inductance plethysmography and pulse oximetry. The effect of HB on NS was assessed during standardized bottle-feeding. A second recording was performed 48 h after recovery from HB (D3). RESULTS Swallows were less frequent (p = 0.003) and of smaller volume (p = 0.01) in HB lambs while swallowing frequency was decreased (p = 0.004). These differences disappeared after HB normalization. Swallowing-breathing coordination was impaired in HB lambs, with a decrease in percent time with NS burst-related apneas/hypopneas at D0 and D3. Simultaneously, HB lambs tended to experience more severe desaturations (<80%) during bottle-feeding. Finally, following bottle-feeding, the respiratory rate was significantly lower, along with an increased apnea duration in HB lambs. CONCLUSIONS Swallowing and swallowing-breathing coordination are altered by acute moderate HB in preterm lambs. Decreased efficiency at bottle-feeding is accompanied by continuation of breathing during swallow bursts, which may promote lung aspiration.
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Affiliation(s)
- Mélisande Bourgoin-Heck
- Respiratory Physiology Department, CHU de Poitiers, Faculté de Médecine et de Pharmacie, Université de Poitiers, Poitiers, France
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Vaz AR, Delgado-Esteban M, Brito MA, Bolaños JP, Brites D, Almeida A. Bilirubin selectively inhibits cytochrome c oxidase activity and induces apoptosis in immature cortical neurons: assessment of the protective effects of glycoursodeoxycholic acid. J Neurochem 2009; 112:56-65. [PMID: 19818102 DOI: 10.1111/j.1471-4159.2009.06429.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
High levels of unconjugated bilirubin (UCB) may initiate encephalopathy in neonatal life, mainly in pre-mature infants. The molecular mechanisms of this bilirubin-induced neurologic dysfunction (BIND) are not yet clarified and no neuroprotective strategy is currently worldwide accepted. Here, we show that UCB, at conditions mimicking those of hyperbilirubinemic newborns (50 microM UCB in the presence of 100 muM human serum albumin), rapidly (within 1 h) inhibited cytochrome c oxidase activity and ascorbate-driven oxygen consumption in 3 days in vitro rat cortical neurons. This was accompanied by a bioenergetic and oxidative crisis, and apoptotic cell death, as judged by the collapse of the inner-mitochondrial membrane potential, increased glycolytic activity, superoxide anion radical production, and ATP release, as well as disruption of glutathione redox status. Furthermore, the antioxidant compound glycoursodeoxycholic acid (GUDCA) fully abrogated UCB-induced cytochrome c oxidase inhibition and significantly prevented oxidative stress, metabolic alterations, and cell demise. These results suggest that the neurotoxicity associated with neonatal bilirubin-induced encephalopathy occur through a dysregulation of energy metabolism, and supports the notion that GUDCA may be useful in the treatment of BIND.
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Affiliation(s)
- Ana Rita Vaz
- Centro de Patogénese Molecular - UBMBE/iMed.UL, Faculdade de Farmácia, University of Lisbon, Lisbon, Portugal
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Abstract
There is strong evidence that prolonged, moderate cerebral hypothermia initiated within a few hours after severe hypoxia-ischemia and continued until resolution of the acute phase of delayed cell death can reduce neuronal loss and improve behavioral recovery in term infants and adults after cardiac arrest. This review examines the evidence that mild to moderate hypothermia is protective after hypoxia-ischemia in models of preterm brain injury and evaluates the potential risks. Induced hypothermia likely has potential to significantly reduce disability. Cautious, systematic trials are essential before hypothermia can be used in these vulnerable infants.
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Affiliation(s)
- Alistair Jan Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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Mejia GB, Sanz CR, Avila MM, Peraza AV, Guzmán DC, Olguín HJ, Ramírez AM, Cruz EG. Experimental hemolysis model to study bilirubin encephalopathy in rat brain. J Neurosci Methods 2008; 168:35-41. [DOI: 10.1016/j.jneumeth.2007.09.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 09/07/2007] [Accepted: 09/07/2007] [Indexed: 11/22/2022]
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Brito MA, Rosa AI, Falcão AS, Fernandes A, Silva RFM, Butterfield DA, Brites D. Unconjugated bilirubin differentially affects the redox status of neuronal and astroglial cells. Neurobiol Dis 2008; 29:30-40. [PMID: 17869125 DOI: 10.1016/j.nbd.2007.07.023] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 07/11/2007] [Accepted: 07/23/2007] [Indexed: 11/21/2022] Open
Abstract
We investigated whether nerve cell damage by unconjugated bilirubin (UCB) is mediated by oxidative stress and ascertained the neuronal and astroglial susceptibility to injury. Several oxidative stress biomarkers and cell death were determined following incubation of neurons and astrocytes isolated from rat cortical cerebrum with UCB (0.01-1.0 microM). We show that UCB induces a dose-dependent increase in neuronal death in parallel with the oxidation of cell components and a decrease in the intracellular glutathione content. Comparison of the results obtained in both cell types demonstrates that neurons are more vulnerable than astrocytes to oxidative injury by UCB, for which accounts the lower glutathione stores in neuronal cells. Moreover, neuronal oxidative injury is prevented by supplementation with N-acetylcysteine, a glutathione precursor, whereas astroglial sensitivity to UCB is enhanced by inhibition of glutathione synthesis, using buthionine sulfoximine. Collectively, we demonstrate that oxidative stress is involved in UCB neurotoxicity and depict a new therapeutic approach for UCB-induced oxidative damage.
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Affiliation(s)
- Maria A Brito
- Centro de Patogénese Molecular - Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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Strauss KA, Robinson DL, Vreman HJ, Puffenberger EG, Hart G, Morton DH. Management of hyperbilirubinemia and prevention of kernicterus in 20 patients with Crigler-Najjar disease. Eur J Pediatr 2006; 165:306-19. [PMID: 16435131 DOI: 10.1007/s00431-005-0055-2] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Accepted: 11/15/2005] [Indexed: 10/25/2022]
Abstract
We summarize the treatment of 20 patients with Crigler-Najjar disease (CND) managed at one center from 1989 to 2005 (200 patient-years). Diagnosis was confirmed by sequencing the UGTA1A gene. Nineteen patients had a severe (type 1) phenotype. Major treatment goals were to maintain the bilirubin to albumin concentration ratio at <0.5 in neonates and <0.7 in older children and adults, to avoid drugs known to displace bilirubin from albumin, and to manage temporary exacerbations of hyperbilirubinemia caused by illness or gallstones. A variety of phototherapy systems provided high irradiance over a large body surface. Mean total bilirubin for the group was 16+/-5 mg/dl and increased with age by approximately 0.8 mg/dl per year. The molar ratio of bilirubin to albumin ranged from 0.17 to 0.75 (mean: 0.44). The overall non-surgical hospitalization rate was 0.12 hospitalizations per patient per year; one-half of these were for neonatal hyperbilirubinemia and the remainder were for infectious illnesses. Ten patients (50%) underwent elective laproscopic cholecystectomy for cholelithiasis. No patient required invasive bilirubin removal or developed bilirubin-induced neurological damage under our care. Visual acuity and color discrimination did not differ between CND patients and age-matched sibling controls. Four patients treated with orthotopic liver transplantation were effectively cured of CND, although one suffered significant transplant-related complications.Conclusions. While patients await liver transplantation for CND, hyperbilirubinemia can be managed safely and effectively to prevent kernicterus. Lessons learned from CND can be applied to screening and therapy of non-hemolytic jaundice in otherwise healthy newborns.
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Affiliation(s)
- Kevin A Strauss
- Clinic for Special Children, 535 Bunker Hill Road, Strasburg, PA 17579, USA.
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Land SC. Hochachka's "Hypoxia Defense Strategies" and the development of the pathway for oxygen. Comp Biochem Physiol B Biochem Mol Biol 2005; 139:415-33. [PMID: 15544965 DOI: 10.1016/j.cbpc.2004.02.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/26/2004] [Accepted: 02/29/2004] [Indexed: 12/17/2022]
Abstract
Hochachka's "Hypoxia Defense Strategies" identify oxygen signalling, metabolic arrest, channel arrest and coordinated suppression of ATP turnover rates as key factors that determine the ability of organisms to survive exposure to chronic hypoxia. In this review, I assess the developmental role played by these phenomena in the morphogenesis of the gas exchange tissues that define the pathway for oxygen transport to cytochrome c oxidase. Key areas of regulation lie in: (I) the suppression of fetal mitochondrial oxidative function in hand with mitochondrial biogenesis (metabolic arrest), (II) the role of hypoxia-driven oxygen signalling pathways in directing the scope of non-differentiated stem cell proliferation in placenta and lung development and (III) the regulation of epithelial fluid secretion/absorption in the lung through the oxygen-dependent modulation of Na+ conductance pathways. The identification of developmental roles for Hochachka's "Hypoxia Defense Strategies" in directing the morphogenesis of gas exchange structures bears with it the implication that these strategies are fundamental to establishing the scope for aerobic metabolic performance throughout life.
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Affiliation(s)
- Stephen C Land
- Division of Maternal and Child Health Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
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Abstract
Cytotoxicity by unconjugated bilirubin involves disturbances of membrane structure, excitotoxicity and cell death. These events were reported to trigger elevated free radicals production and impairment of calcium homeostasis, and to result in loss of cell membrane integrity. Therefore, this study was designed to investigate whether interaction of clinically relevant concentrations of free unconjugated bilirubin with synaptosomal membrane vesicles could be linked to oxidative stress, cytosolic calcium accumulation and perturbation of membrane function. Synaptosomal vesicles were prepared from gerbil cortical brain tissue and incubated with purified bilirubin (<or=1 microM), for 4 h at 37 degrees C. Intracellular concentrations of reactive oxygen species (ROS) and calcium were determined by dichlorofluorescin and BAPTA fluorescent probes, respectively. Membrane protein and lipid oxidation were evaluated by immunocytochemistry and phosphatidylserine exposure by annexin V binding. Levels of reduced and oxidized glutathione (GSH and GSSG, respectively), as well as activities of Mg(2+)-ATPase aminophospholipid translocase (flippase) and Na(+),K(+)-ATPase, were also measured. Our results showed that bilirubin induced oxidative stress, due to a rise in lipid (>or=10%, P<0.05) and protein oxidation (>or=20%, P<0.01), ROS content (approximately 17%, P<0.01), and a decrease in GSH/GSSG ratio (>30%, P<0.01). In addition, synaptosomes exposed to bilirubin exhibited increased externalization of phosphatidylserine (approximately 10%, P<0.05), together with decreased flippase and NA(+),K(+)-ATPase (>or=15%, P<0.05) activities, events that were accompanied by enhanced intracellular calcium levels ( approximately 20%, P<0.01). The data obtained point out that interaction of unconjugated bilirubin with synaptosomal membrane vesicles leads to oxidative injury, loss of membrane asymmetry and functionality, and calcium intrusion, thus potentially contributing to the pathogenesis of encephalopathy by hyperbilirubinemia.
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Affiliation(s)
- Maria Alexandra Brito
- Centro de Patogénese Molecular--UBMBE, Faculdade de Farmácia, University of Lisbon, Av. das Forças Armadas, 1600-083 Lisbon, Portugal.
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