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Barros LF, Ruminot I, Sandoval PY, San Martín A. Enlightening brain energy metabolism. Neurobiol Dis 2023:106211. [PMID: 37352985 DOI: 10.1016/j.nbd.2023.106211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/06/2023] [Accepted: 06/20/2023] [Indexed: 06/25/2023] Open
Abstract
Brain tissue metabolism is distributed across several cell types and subcellular compartments, which activate at different times and with different temporal patterns. The introduction of genetically-encoded fluorescent indicators that are imaged using time-lapse microscopy has opened the possibility of studying brain metabolism at cellular and sub-cellular levels. There are indicators for sugars, monocarboxylates, Krebs cycle intermediates, amino acids, cofactors, and energy nucleotides, which inform about relative levels, concentrations and fluxes. This review offers a brief survey of the metabolic indicators that have been validated in brain cells, with some illustrative examples from the literature. Whereas only a small fraction of the metabolome is currently accessible to fluorescent probes, there are grounds to be optimistic about coming developments and the application of these tools to the study of brain disease.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile.
| | - I Ruminot
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Ciencias para el Cuidado de La Salud, Universidad San Sebastián, Valdivia, Chile
| | - P Y Sandoval
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Ciencias para el Cuidado de La Salud, Universidad San Sebastián, Valdivia, Chile
| | - A San Martín
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Ciencias para el Cuidado de La Salud, Universidad San Sebastián, Valdivia, Chile
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Abstract
Information processing imposes urgent metabolic demands on neurons, which have negligible energy stores and restricted access to fuel. Here, we discuss metabolic recruitment, the tissue-level phenomenon whereby active neurons harvest resources from their surroundings. The primary event is the neuronal release of K+ that mirrors workload. Astrocytes sense K+ in exquisite fashion thanks to their unique coexpression of NBCe1 and α2β2 Na+/K+ ATPase, and within seconds switch to Crabtree metabolism, involving GLUT1, aerobic glycolysis, transient suppression of mitochondrial respiration, and lactate export. The lactate surge serves as a secondary recruiter by inhibiting glucose consumption in distant cells. Additional recruiters are glutamate, nitric oxide, and ammonium, which signal over different spatiotemporal domains. The net outcome of these events is that more glucose, lactate, and oxygen are made available. Metabolic recruitment works alongside neurovascular coupling and various averaging strategies to support the inordinate dynamic range of individual neurons.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile; .,Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile;
| | - I Ruminot
- Centro de Estudios Científicos (CECs), Valdivia, Chile; .,Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile;
| | - T Sotelo-Hitschfeld
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - R Lerchundi
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), MIRCen, Fontenay-aux-Roses, France
| | - I Fernández-Moncada
- NeuroCentre Magendie, INSERM U1215, University of Bordeaux, Bordeaux, France
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Abstract
The energy cost of information processing is thought to be chiefly neuronal, with a minor fraction attributed to glial cells. However, there is compelling evidence that astrocytes capture synaptic K+ using their Na+/K+ ATPase, and not solely through Kir4.1 channels as was once thought. When this active buffering is taken into account, the cost of astrocytes rises by >200%. Gram-per-gram, astrocytes turn out to be as expensive as neurons. This conclusion is supported by 3D reconstruction of the neuropil showing similar mitochondrial densities in neurons and astrocytes, by cell-specific transcriptomics and proteomics, and by the rates of the tricarboxylic acid cycle. Possible consequences for reactive astrogliosis and brain disease are discussed.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos - CECs, Valdivia, Chile
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San Martín A, Arce-Molina R, Aburto C, Baeza-Lehnert F, Barros LF, Contreras-Baeza Y, Pinilla A, Ruminot I, Rauseo D, Sandoval PY. Visualizing physiological parameters in cells and tissues using genetically encoded indicators for metabolites. Free Radic Biol Med 2022; 182:34-58. [PMID: 35183660 DOI: 10.1016/j.freeradbiomed.2022.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 02/07/2023]
Abstract
The study of metabolism is undergoing a renaissance. Since the year 2002, over 50 genetically-encoded fluorescent indicators (GEFIs) have been introduced, capable of monitoring metabolites with high spatial/temporal resolution using fluorescence microscopy. Indicators are fusion proteins that change their fluorescence upon binding a specific metabolite. There are indicators for sugars, monocarboxylates, Krebs cycle intermediates, amino acids, cofactors, and energy nucleotides. They permit monitoring relative levels, concentrations, and fluxes in living systems. At a minimum they report relative levels and, in some cases, absolute concentrations may be obtained by performing ad hoc calibration protocols. Proper data collection, processing, and interpretation are critical to take full advantage of these new tools. This review offers a survey of the metabolic indicators that have been validated in mammalian systems. Minimally invasive, these indicators have been instrumental for the purposes of confirmation, rebuttal and discovery. We envision that this powerful technology will foster metabolic physiology.
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Affiliation(s)
- A San Martín
- Centro de Estudios Científicos (CECs), Valdivia, Chile.
| | - R Arce-Molina
- Centro de Estudios Científicos (CECs), Valdivia, Chile
| | - C Aburto
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Universidad Austral de Chile, Valdivia, Chile
| | | | - L F Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile
| | - Y Contreras-Baeza
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Universidad Austral de Chile, Valdivia, Chile
| | - A Pinilla
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Universidad Austral de Chile, Valdivia, Chile
| | - I Ruminot
- Centro de Estudios Científicos (CECs), Valdivia, Chile
| | - D Rauseo
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Universidad Austral de Chile, Valdivia, Chile
| | - P Y Sandoval
- Centro de Estudios Científicos (CECs), Valdivia, Chile
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos, Valdivia, 5110466, Chile
| | - B Weber
- Institute of Pharmacology and Toxicology, University of Zurich, and Neuroscience Center Zurich, Zurich, CH-8057, Switzerland
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Barros LF, Weber B. CrossTalk proposal: an important astrocyte-to-neuron lactate shuttle couples neuronal activity to glucose utilisation in the brain. J Physiol 2018; 596:347-350. [PMID: 29292516 DOI: 10.1113/jp274944] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- L F Barros
- Centro de Estudios Científicos, Valdivia, 5110466, Chile
| | - B Weber
- Institute of Pharmacology and Toxicology, University of Zurich, and Neuroscience Center Zurich, Zurich, CH-8057, Switzerland
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Dias MS, Semmler R, Moreira DS, de Menezes MO, Barros LF, Ribeiro RV, Koskinas MF. SUMCOR: Cascade summing correction for volumetric sources applying MCNP6. Appl Radiat Isot 2017; 134:205-211. [PMID: 28939243 DOI: 10.1016/j.apradiso.2017.09.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 09/04/2017] [Accepted: 09/10/2017] [Indexed: 10/18/2022]
Abstract
The main features of code SUMCOR developed for cascade summing correction for volumetric sources are described. MCNP6 is used to track histories starting from individual points inside the volumetric source, for each set of cascade transitions from the radionuclide. Total and FEP efficiencies are calculated for all gamma-rays and X-rays involved in the cascade. Cascade summing correction is based on the matrix formalism developed by Semkow et al. (1990). Results are presented applying the experimental data sent to the participants of two intercomparisons organized by the ICRM-GSWG and coordinated by Dr. Marie-Cristine Lépy from the Laboratoire National Henri Becquerel (LNE-LNHB), CEA, in 2008 and 2010, respectively and compared to the other participants in the intercomparisons.
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Affiliation(s)
- M S Dias
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil.
| | - R Semmler
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
| | - D S Moreira
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
| | - M O de Menezes
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
| | - L F Barros
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
| | - R V Ribeiro
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
| | - M F Koskinas
- Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000 São Paulo, SP, Brazil
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Vegh Z, Burisch J, Pedersen N, Kaimakliotis I, Duricova D, Bortlik M, Vinding KK, Avnstrøm S, Olsen J, Nielsen KR, Katsanos KH, Tsianos EV, Lakatos L, Schwartz D, Odes S, D'Incà R, Beltrami M, Kiudelis G, Kupcinskap L, Jucov A, Turcan S, Barros LF, Magro F, Lazar D, Goldis A, de Castro L, Hernandez V, Niewiadomski O, Bell S, Langholz E, Munkholm P, Lakatos PL. Treatment Steps, Surgery, and Hospitalization Rates During the First Year of Follow-up in Patients with Inflammatory Bowel Diseases from the 2011 ECCO-Epicom Inception Cohort. J Crohns Colitis 2015; 9:747-53. [PMID: 26055976 DOI: 10.1093/ecco-jcc/jjv099] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [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: 03/30/2015] [Accepted: 04/28/2015] [Indexed: 12/27/2022]
Abstract
BACKGROUND AND AIMS The ECCO-EpiCom study investigates the differences in the incidence and therapeutic management of inflammatory bowel diseases [IBD] between Eastern and Western Europe. The aim of this study was to analyse the differences in the disease phenotype, medical therapy, surgery, and hospitalization rates in the ECCO-EpiCom 2011 inception cohort during the first year after diagnosis. METHODS Nine Western, five Eastern European centres and one Australian centre with 258 Crohn's disease [CD], 380 ulcerative colitis [UC] and 71 IBD unclassified [IBDU] patients [female/male: 326/383; mean age at diagnosis: 40.9 years, SD: 17.3 years] participated. Patients' data were registered and entered in the web-based ECCO-EpiCom database [www.epicom-ecco.eu]. RESULTS In CD, 36 [19%] Western Europe/Australian and 6 [9%] Eastern European patients received biological therapy [p = 0.04], but the immunosuppressive [IS] use was equal and high in these regions [Eastern Europe vs Western Europe/Australia: 53% vs 45%; p = 0.27]. Surgery was performed in 17 [24%] CD patients in Eastern Europe and 13 [7%] in Western Europe/Australia [p < 0.001, pLogRank = 0.001]. Of CD patients from Eastern Europe, 24 [34%] were hospitalized, and 39 [21%] from Western Europe/Australia, [p = 0.02, pLogRank = 0.01]. In UC, exposure to biologicals and colectomy rates were low and hospitalization rates did not differ between these regions during the 1-year follow-up period [16% vs 16%; p = 0.93]. CONCLUSIONS During the first year after diagnosis, surgery and hospitalization rates were significantly higher in CD patients in Eastern Europe compared with Western Europe/Australia, whereas significantly more CD patients were treated with biologicals in the Western Europe/Australian centres.
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Affiliation(s)
- Z Vegh
- First Department of Medicine, Semmelweis University, Budapest, Hungary
| | - J Burisch
- Gastrounit, Medical Section, Hvidovre University Hospital, Hvidovre, Denmark
| | - N Pedersen
- Gastroenterology Department, Slagelse University Hospital, Slagelse, Denmark
| | | | - D Duricova
- IBD Centre ISCARE, Charles University, Prague, Czech Republic
| | - M Bortlik
- IBD Centre ISCARE, Charles University, Prague, Czech Republic
| | - K Kofod Vinding
- Digestive Disease Centre, Medical Section, Herlev University Hospital, Copenhagen, Denmark
| | - S Avnstrøm
- Department of Medicine, Amager Hospital, Amager, Denmark
| | - J Olsen
- Medical Department, National Hospital of the Faroe Islands, Torshavn, Faroe Islands
| | - K R Nielsen
- Medical Department, National Hospital of the Faroe Islands, Torshavn, Faroe Islands
| | - K H Katsanos
- First Division of Internal Medicine and Division of Gastroenterology, Faculty of Medicine, University of Ioannina, Ioannina, Greece
| | - E V Tsianos
- First Division of Internal Medicine and Division of Gastroenterology, Faculty of Medicine, University of Ioannina, Ioannina, Greece
| | - L Lakatos
- Department of Medicine, Csolnoky F. Province Hospital, Veszprem, Hungary
| | - D Schwartz
- First Department of Medicine, Semmelweis University, Budapest, Hungary
| | - S Odes
- Department of Gastroenterology and Hepatology, Soroka Medical Centre and Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - R D'Incà
- UO Gastroenterologia, Azienda Ospedaliera-Università di Padova, Padova, Italy On behalf of the EpiCom Northern Italy centre based in Crema, Cremona, Firenze, Forlì & Padova and Reggio Emilia, Italy
| | - M Beltrami
- Degenza Breve Internistica e Centro M.I.C.I.-Azienda Ospedaliera Arcispedale S Maria Nuova, Reggio Emilia, Italy On behalf of the EpiCom Northern Italy centre based in Crema, Cremona, Firenze, Forlì & Padova and Reggio Emilia, Italy
| | - G Kiudelis
- Institute for Digestive Research, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - L Kupcinskap
- Institute for Digestive Research, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - A Jucov
- Department of Gastroenterology, State University of Medicine and Pharmacy, Chisinau, Republic of Moldova
| | - S Turcan
- Department of Gastroenterology, State University of Medicine and Pharmacy, Chisinau, Republic of Moldova
| | - L F Barros
- Hospital de Vale de Sousa, Porto, Portugal
| | - F Magro
- Department of Gastroenterology, Hospital de São João, Porto, Portugal Department of Pharmacology and Therapeutics, Oporto Medical School, Porto, Portugal MedInUP-Centre for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - D Lazar
- Clinic of Gastroenterology, University of Medicine 'Victor Babes', Timisoara, Romania
| | - A Goldis
- Clinic of Gastroenterology, University of Medicine 'Victor Babes', Timisoara, Romania
| | - L de Castro
- Department of Gastroenterology, Grupo de Investigación en Patología Digestiva, Instituto de Investigación Biomedica [IBI], Xerencia de Xestión Integrada de Vigo, SERGAS, Vigo, Spain
| | - V Hernandez
- Department of Gastroenterology, Grupo de Investigación en Patología Digestiva, Instituto de Investigación Biomedica [IBI], Xerencia de Xestión Integrada de Vigo, SERGAS, Vigo, Spain
| | - O Niewiadomski
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - S Bell
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - E Langholz
- Department C, Gastroenterology Section, Herlev and Gentofte Hospital, Hellerup, Denmark
| | - P Munkholm
- Gastro Unit, Medical Section, North Zealand Hospital, University of Copenhagen, Denmark
| | - P L Lakatos
- First Department of Medicine, Semmelweis University, Budapest, Hungary
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Maturana JL, Niechi I, Silva E, Huerta H, Cataldo R, Härtel S, Barros LF, Galindo M, Tapia JC. Transactivation activity and nucleocytoplasmic transport of β-catenin are independently regulated by its C-terminal end. Gene 2015; 573:115-22. [PMID: 26187068 DOI: 10.1016/j.gene.2015.07.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 07/11/2015] [Indexed: 11/20/2022]
Abstract
The key protein in the canonical Wnt pathway is β-catenin, which is phosphorylated both in absence and presence of Wnt signals by different kinases. Upon activation in the cytoplasm, β-catenin can enter into the nucleus to transactivate target gene expression, many of which are cancer-related genes. The mechanism governing β-catenin's nucleocytoplasmic transport has been recently unvealed, although phosphorylation at its C-terminal end and its functional consequences are not completely understood. Serine 646 of β-catenin is a putative CK2 phosphorylation site and lies in a region which has been proposed to be important for its nucleocytoplasmic transport and transactivation activity. This residue was mutated to aspartic acid mimicking CK2-phosphorylation and its effects on β-catenin activity as well as localization were explored. β-Catenin S6464D did not show significant differences in both transcriptional activity and nuclear localization compared to the wild-type form, but displayed a characteristic granular nuclear pattern. Three-dimensional models of nuclei were constructed which showed differences in number and volume of granules, being those from β-catenin S646D more and smaller than the wild-type form. FRAP microscopy was used to compare nuclear export of both proteins which showed a slightly higher but not significant retention of β-catenin S646D. Altogether, these results show that C-terminal phosphorylation of β-catenin seems to be related with its nucleocytoplasmic transport but not transactivation activity.
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Affiliation(s)
- J L Maturana
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - I Niechi
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - E Silva
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - H Huerta
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - R Cataldo
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - S Härtel
- Laboratory for Scientific Image Analysis (SCIAN-Lab), ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - L F Barros
- Centro de Estudios Cientificos, Valdivia, Chile
| | - M Galindo
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - J C Tapia
- Program of Cellular and Molecular Biology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile.
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Vegh Z, Burisch J, Pedersen N, Kaimakliotis I, Duricova D, Bortlik M, Avnstrøm S, Vinding KK, Olsen J, Nielsen KR, Katsanos KH, Tsianos EV, Lakatos L, Schwartz D, Odes S, Lupinacci G, De Padova A, Jonaitis L, Kupcinskas L, Turcan S, Tighineanu O, Mihu I, Barros LF, Magro F, Lazar D, Goldis A, Fernandez A, Hernandez V, Niewiadomski O, Bell S, Langholz E, Munkholm P, Lakatos PL. Incidence and initial disease course of inflammatory bowel diseases in 2011 in Europe and Australia: results of the 2011 ECCO-EpiCom inception cohort. J Crohns Colitis 2014; 8:1506-15. [PMID: 24998983 DOI: 10.1016/j.crohns.2014.06.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/07/2014] [Accepted: 06/10/2014] [Indexed: 12/30/2022]
Abstract
BACKGROUND AND AIMS The aim of the present study was to validate the IBD (inflammatory bowel diseases) incidence reported in the 2010 ECCO-EpiCom (European Crohn's and Colitis Organization-Epidemiological Committee) inception cohort by including a second independent inception cohort from participating centers in 2011 and an Australian center to investigate whether there is a difference in the incidence of IBD between Eastern and Western European countries and Australia. METHODS Fourteen centers from 5 Eastern and 9 Western European countries and one center from Australia participated in the ECCO-EpiCom 2011 inception cohort. Patients' data regarding disease type, socio-demographic factors, extraintestinal manifestations and therapy were entered into the Web-based EpiCom database, www.ecco-epicom.eu. RESULTS A total of 711 adult patients were diagnosed during the inclusion year 2011, 178 (25%) from Eastern, 461 (65%) from Western Europe and 72 (10%) from Australia; 259 (37%) patients were diagnosed with Crohn's disease, 380 (53%) with ulcerative colitis and 72 (10%) with IBD unclassified. The mean annual incidence rate for IBD was 11.3/100,000 in Eastern Europe, 14.0/100,000 in Western Europe and 30.3/100,000 in Australia. Significantly more patients were diagnosed with complicated disease at diagnosis in Eastern Europe compared to Western Europe (43% vs. 27%, p=0.02). CONCLUSION Incidence rates, disease phenotype and initial treatment characteristics in the 2011 ECCO-EpiCom cohort were not significantly different from that reported in the 2010 cohort.
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Affiliation(s)
- Z Vegh
- Digestive Disease Centre, Medical Section, Herlev University Hospital, Copenhagen, Denmark; 1st Department of Medicine, Semmelweis University, Budapest, Hungary.
| | - J Burisch
- Digestive Disease Centre, Medical Section, Herlev University Hospital, Copenhagen, Denmark
| | - N Pedersen
- Digestive Disease Centre, Medical Section, Herlev University Hospital, Copenhagen, Denmark
| | | | - D Duricova
- IBD Centre ISCARE, Charles University, Prague, Czech Republic
| | - M Bortlik
- IBD Centre ISCARE, Charles University, Prague, Czech Republic
| | - S Avnstrøm
- Department of Medicine, Amager Hospital, Amager, Denmark
| | | | - J Olsen
- Medical Department, The National Hospital of the Faroe Islands, Torshavn, Faroe Islands
| | - K R Nielsen
- Medical Department, The National Hospital of the Faroe Islands, Torshavn, Faroe Islands
| | - K H Katsanos
- 1st Division of Internal Medicine and Division of Gastroenterology, Faculty of Medicine, University of Ioannina, Ioannina, Greece
| | - E V Tsianos
- 1st Division of Internal Medicine and Division of Gastroenterology, Faculty of Medicine, University of Ioannina, Ioannina, Greece
| | - L Lakatos
- 1st Department of Medicine, Semmelweis University, Budapest, Hungary
| | - D Schwartz
- Department of Gastroenterology and Hepatology, Soroka Medical Centre and Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - S Odes
- Department of Gastroenterology and Hepatology, Soroka Medical Centre and Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - G Lupinacci
- U.O.Gastroenterologia ed Endoscopia, Ospedale Maggiore di Crema, Crema, Italy; On behalf of the EpiCom Northern Italy centre based in Crema, Cremona, Firenze, Forlì & Padova and Reggio Emilia, Italy
| | - A De Padova
- On behalf of the EpiCom Northern Italy centre based in Crema, Cremona, Firenze, Forlì & Padova and Reggio Emilia, Italy; U.O. Gastroenterologia ed Endoscopia Digestiva, University of Ioannina, Forlì, Italy
| | - L Jonaitis
- Institute for Digestive Research, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - L Kupcinskas
- Institute for Digestive Research, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - S Turcan
- Department of Gastroenterology, State University of Medicine and Pharmacy, Chisinau, Republic of Moldova
| | - O Tighineanu
- Department of Paediatric Gastroenterology, Centre of Mother and Child, Chisinau, Republic of Moldova
| | - I Mihu
- Department of Paediatric Gastroenterology, Centre of Mother and Child, Chisinau, Republic of Moldova
| | - L F Barros
- Hospital de Vale de Sousa, Porto, Portugal
| | - F Magro
- Department of Gastroenterology, Hospital de São João, Porto, Portugal; Department of Pharmacology and Therapeutics, Oporto Medical School, Porto, Portugal; MedInUP-Centre for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - D Lazar
- Clinic of Gastroenterology, University of Medicine 'Victor Babes', Timisoara, Romania
| | - A Goldis
- Clinic of Gastroenterology, University of Medicine 'Victor Babes', Timisoara, Romania
| | - A Fernandez
- Gastroenterology Department, POVISA Hospital, Vigo, Spain
| | - V Hernandez
- Gastroenterology Department, Complexo Hospitalario Universitario de Vigo, Vigo, Spain
| | - O Niewiadomski
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - S Bell
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - E Langholz
- Department of Medical Gastroenterology, Gentofte Hospital, Copenhagen, Denmark
| | - P Munkholm
- Digestive Disease Centre, Medical Section, Herlev University Hospital, Copenhagen, Denmark
| | - P L Lakatos
- 1st Department of Medicine, Semmelweis University, Budapest, Hungary
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Burisch J, Pedersen N, Čuković-Čavka S, Brinar M, Kaimakliotis I, Duricova D, Shonová O, Vind I, Avnstrøm S, Thorsgaard N, Andersen V, Krabbe S, Dahlerup JF, Salupere R, Nielsen KR, Olsen J, Manninen P, Collin P, Tsianos EV, Katsanos KH, Ladefoged K, Lakatos L, Björnsson E, Ragnarsson G, Bailey Y, Odes S, Schwartz D, Martinato M, Lupinacci G, Milla M, De Padova A, D'Incà R, Beltrami M, Kupcinskas L, Kiudelis G, Turcan S, Tighineanu O, Mihu I, Magro F, Barros LF, Goldis A, Lazar D, Belousova E, Nikulina I, Hernandez V, Martinez-Ares D, Almer S, Zhulina Y, Halfvarson J, Arebi N, Sebastian S, Lakatos PL, Langholz E, Munkholm P. East-West gradient in the incidence of inflammatory bowel disease in Europe: the ECCO-EpiCom inception cohort. Gut 2014. [PMID: 23604131 DOI: 10.1136/gutjnl-2013-3046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE The incidence of inflammatory bowel disease (IBD) is increasing in Eastern Europe. The reasons for these changes remain unknown. The aim of this study was to investigate whether an East-West gradient in the incidence of IBD in Europe exists. DESIGN A prospective, uniformly diagnosed, population based inception cohort of IBD patients in 31 centres from 14 Western and eight Eastern European countries covering a total background population of approximately 10.1 million people was created. One-third of the centres had previous experience with inception cohorts. Patients were entered into a low cost, web based epidemiological database, making participation possible regardless of socioeconomic status and prior experience. RESULTS 1515 patients aged 15 years or older were included, of whom 535 (35%) were diagnosed with Crohn's disease (CD), 813 (54%) with ulcerative colitis (UC) and 167 (11%) with IBD unclassified (IBDU). The overall incidence rate ratios in all Western European centres were 1.9 (95% CI 1.5 to 2.4) for CD and 2.1 (95% CI 1.8 to 2.6) for UC compared with Eastern European centres. The median crude annual incidence rates per 100,000 in 2010 for CD were 6.5 (range 0-10.7) in Western European centres and 3.1 (range 0.4-11.5) in Eastern European centres, for UC 10.8 (range 2.9-31.5) and 4.1 (range 2.4-10.3), respectively, and for IBDU 1.9 (range 0-39.4) and 0 (range 0-1.2), respectively. In Western Europe, 92% of CD, 78% of UC and 74% of IBDU patients had a colonoscopy performed as the diagnostic procedure compared with 90%, 100% and 96%, respectively, in Eastern Europe. 8% of CD and 1% of UC patients in both regions underwent surgery within the first 3 months of the onset of disease. 7% of CD patients and 3% of UC patients from Western Europe received biological treatment as rescue therapy. Of all European CD patients, 20% received only 5-aminosalicylates as induction therapy. CONCLUSIONS An East-West gradient in IBD incidence exists in Europe. Among this inception cohort--including indolent and aggressive cases--international guidelines for diagnosis and initial treatment are not being followed uniformly by physicians.
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Affiliation(s)
- J Burisch
- Digestive Disease Centre, Medical Section, Herlev University Hospital, , Copenhagen, Denmark
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12
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Burisch J, Pedersen N, Čuković-Čavka S, Brinar M, Kaimakliotis I, Duricova D, Shonová O, Vind I, Avnstrøm S, Thorsgaard N, Andersen V, Krabbe S, Dahlerup JF, Salupere R, Nielsen KR, Olsen J, Manninen P, Collin P, Tsianos EV, Katsanos KH, Ladefoged K, Lakatos L, Björnsson E, Ragnarsson G, Bailey Y, Odes S, Schwartz D, Martinato M, Lupinacci G, Milla M, De Padova A, D'Incà R, Beltrami M, Kupcinskas L, Kiudelis G, Turcan S, Tighineanu O, Mihu I, Magro F, Barros LF, Goldis A, Lazar D, Belousova E, Nikulina I, Hernandez V, Martinez-Ares D, Almer S, Zhulina Y, Halfvarson J, Arebi N, Sebastian S, Lakatos PL, Langholz E, Munkholm P. East-West gradient in the incidence of inflammatory bowel disease in Europe: the ECCO-EpiCom inception cohort. Gut 2014; 63:588-97. [PMID: 23604131 DOI: 10.1136/gutjnl-2013-304636] [Citation(s) in RCA: 263] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The incidence of inflammatory bowel disease (IBD) is increasing in Eastern Europe. The reasons for these changes remain unknown. The aim of this study was to investigate whether an East-West gradient in the incidence of IBD in Europe exists. DESIGN A prospective, uniformly diagnosed, population based inception cohort of IBD patients in 31 centres from 14 Western and eight Eastern European countries covering a total background population of approximately 10.1 million people was created. One-third of the centres had previous experience with inception cohorts. Patients were entered into a low cost, web based epidemiological database, making participation possible regardless of socioeconomic status and prior experience. RESULTS 1515 patients aged 15 years or older were included, of whom 535 (35%) were diagnosed with Crohn's disease (CD), 813 (54%) with ulcerative colitis (UC) and 167 (11%) with IBD unclassified (IBDU). The overall incidence rate ratios in all Western European centres were 1.9 (95% CI 1.5 to 2.4) for CD and 2.1 (95% CI 1.8 to 2.6) for UC compared with Eastern European centres. The median crude annual incidence rates per 100,000 in 2010 for CD were 6.5 (range 0-10.7) in Western European centres and 3.1 (range 0.4-11.5) in Eastern European centres, for UC 10.8 (range 2.9-31.5) and 4.1 (range 2.4-10.3), respectively, and for IBDU 1.9 (range 0-39.4) and 0 (range 0-1.2), respectively. In Western Europe, 92% of CD, 78% of UC and 74% of IBDU patients had a colonoscopy performed as the diagnostic procedure compared with 90%, 100% and 96%, respectively, in Eastern Europe. 8% of CD and 1% of UC patients in both regions underwent surgery within the first 3 months of the onset of disease. 7% of CD patients and 3% of UC patients from Western Europe received biological treatment as rescue therapy. Of all European CD patients, 20% received only 5-aminosalicylates as induction therapy. CONCLUSIONS An East-West gradient in IBD incidence exists in Europe. Among this inception cohort--including indolent and aggressive cases--international guidelines for diagnosis and initial treatment are not being followed uniformly by physicians.
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Affiliation(s)
- J Burisch
- Digestive Disease Centre, Medical Section, Herlev University Hospital, , Copenhagen, Denmark
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13
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Barros LF, San Martín A, Sotelo-Hitschfeld T, Lerchundi R, Fernández-Moncada I, Ruminot I, Gutiérrez R, Valdebenito R, Ceballo S, Alegría K, Baeza-Lehnert F, Espinoza D. Small is fast: astrocytic glucose and lactate metabolism at cellular resolution. Front Cell Neurosci 2013; 7:27. [PMID: 23526722 PMCID: PMC3605549 DOI: 10.3389/fncel.2013.00027] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/03/2013] [Indexed: 12/28/2022] Open
Abstract
Brain tissue is highly dynamic in terms of electrical activity and energy demand. Relevant energy metabolites have turnover times ranging from milliseconds to seconds and are rapidly exchanged between cells and within cells. Until recently these fast metabolic events were inaccessible, because standard isotopic techniques require use of populations of cells and/or involve integration times of tens of minutes. Thanks to fluorescent probes and recently available genetically-encoded optical nanosensors, this Technology Report shows how it is now possible to monitor the concentration of metabolites in real-time and in single cells. In combination with ad hoc inhibitor-stop protocols, these probes have revealed a key role for K+ in the acute stimulation of astrocytic glycolysis by synaptic activity. They have also permitted detection of the Warburg effect in single cancer cells. Genetically-encoded nanosensors currently exist for glucose, lactate, NADH and ATP, and it is envisaged that other metabolite nanosensors will soon be available. These optical tools together with improved expression systems and in vivo imaging, herald an exciting era of single-cell metabolic analysis.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos Valdivia, Chile
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14
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Jakoby P, Schmidt E, Ruminot I, Gutierrez R, Barros LF, Deitmer JW. Higher Transport and Metabolism of Glucose in Astrocytes Compared with Neurons: A Multiphoton Study of Hippocampal and Cerebellar Tissue Slices. Cereb Cortex 2012; 24:222-31. [DOI: 10.1093/cercor/bhs309] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Sotelo-Hitschfeld T, Fernández-Moncada I, Barros LF. Acute feedback control of astrocytic glycolysis by lactate. Glia 2012; 60:674-80. [PMID: 22290492 DOI: 10.1002/glia.22304] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 01/12/2012] [Indexed: 12/12/2022]
Abstract
Neuronal activity is accompanied by a rapid increase in interstitial lactate, which is hypothesized to serve as a fuel for neurons and a signal for local vasodilation. Using FRET microscopy, we report here that the rate of glycolysis in cultured mice astrocytes can be acutely modulated by physiological changes in extracellular lactate. Glycolytic inhibition by lactate was not accompanied by detectable variations in intracellular pH or intracellular ATP and was not dependent of mitochondrial function. Pyruvate was also inhibitory, suggesting that the effect of lactate is not mediated by the NADH/NAD(+) ratio. We propose that lactate serves as a fast negative feedback signal limiting its own production by astrocytes and therefore the amplitude of the lactate surge. The inhibition of glucose usage by lactate was much stronger in resting astrocytes than in K(+)-stimulated astrocytes, which suggests that lactate may also help diverting glucose from resting to active zones.
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Affiliation(s)
- T Sotelo-Hitschfeld
- Centro de Estudios Científicos (CECs), Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile
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16
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Maia AMA, Barkokebas A, Pires AP, Barros LF, Carvalho AAT, Leão JC. Current use and future perspectives of diagnostic and therapeutic lasers in Oral Medicine. Minerva Stomatol 2008; 57:511-517. [PMID: 19078893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Several diagnostic and therapeutic methods are based on the optical properties of lasers. In therapeutic applications, laser light is absorbed in a specific manner, whereas light is scattered, reflected, or transmitted from different structures. Improvements in laser technology allow new procedures and broaden the scope of applications for both diagnosis and therapy. The focus of laser application in Oral Medicine diagnosis should be early detection of oral squamous cell carcinoma. Novel modalities for the detection of oral malignancy are urgently needed, while others must be continuously improved. Optical coherence tomography and laser-induced fluorescence spectroscopy are currently being studied. In addition to diagnosis of non-malignant lesions, laser therapy has been used based upon the biological reactions and molecular wound healing mechanisms as an alternative for the treatment of a variety of oral soft tissue lesions. The aim of the present article is to review current knowledge and future perspectives of lasers in Oral Medicine.
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Affiliation(s)
- A M A Maia
- Dental Postgraduate Program, Department of Preventive Odontoloy, Federal University of Pernambuco, Recife, Brazil
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17
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Abstract
While glucose is constantly being "pulled" into the brain by hexokinase, its flux across the blood brain barrier (BBB) is allowed by facilitative carriers of the GLUT family. Starting from the microscopic properties of GLUT carriers, and within the constraints imposed by the available experimental data, chiefly NMR spectroscopy, we have generated a numerical model that reveals several hidden features of glucose transport and metabolism in the brain. The half-saturation constant of glucose uptake into the brain (K(t)) is close to 8 mM. GLUT carriers at the BBB are symmetric, show accelerated-exchange, and a K(m) of zero-trans flux (K(zt)) close to 5 mM, determining a ratio of 3.6 between maximum transport rate and net glucose flux (T(max)/CMR(glc)). In spite of the low transporter occupancy, the model shows that for a stimulated hexokinase to pull more glucose into the brain, the number or activity of GLUT carriers must also increase, particularly at the BBB. The endothelium is therefore predicted to be a key modulated element for the fast control of energy metabolism. In addition, the simulations help to explain why mild hypoglycemia may be asymptomatic and reveal that [glucose](brain) (as measured by NMR) should be much more sensitive than glucose flux (as measured by PET) as an indicator of GLUT1 deficiency. In summary, available data from various sources has been integrated in a predictive model based on the microscopic properties of GLUT carriers.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile
| | - Carla X Bittner
- Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Anitsi Loaiza
- Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Omar H Porras
- Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile
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18
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Castro J, Ruminot I, Porras OH, Flores CM, Hermosilla T, Verdugo E, Venegas F, Härtel S, Michea L, Barros LF. ATP steal between cation pumps: a mechanism linking Na+ influx to the onset of necrotic Ca2+ overload. Cell Death Differ 2006; 13:1675-85. [PMID: 16410794 DOI: 10.1038/sj.cdd.4401852] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We set out to identify molecular mechanisms underlying the onset of necrotic Ca(2+) overload, triggered in two epithelial cell lines by oxidative stress or metabolic depletion. As reported earlier, the overload was inhibited by extracellular Ca(2+) chelation and the cation channel blocker gadolinium. However, the surface permeability to Ca(2+) was reduced by 60%, thus discarding a role for Ca(2+) channel/carrier activation. Instead, we registered a collapse of the plasma membrane Ca(2+) ATPase (PMCA). Remarkably, inhibition of the Na(+)/K(+) ATPase rescued the PMCA and reverted the Ca(2+) rise. Thermodynamic considerations suggest that the Ca(2+) overload develops when the Na(+)/K(+) ATPase, by virtue of the Na(+) overload, clamps the ATP phosphorylation potential below the minimum required by the PMCA. In addition to providing the mechanism for the onset of Ca(2+) overload, the crosstalk between cation pumps offers a novel explanation for the role of Na(+) in cell death.
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Affiliation(s)
- J Castro
- Centro de Estudios Científicos CECS, Casilla 1469, Valdivia, Chile
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19
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Castro J, Bittner CX, Humeres A, Montecinos VP, Vera JC, Barros LF. A cytosolic source of calcium unveiled by hydrogen peroxide with relevance for epithelial cell death. Cell Death Differ 2004; 11:468-78. [PMID: 14726961 DOI: 10.1038/sj.cdd.4401372] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Oxidative stress releases intracellular calcium, which plays a pathogenic role in mammalian cell death. Here we report a search for the source of oxidative calcium in HeLa cells based on confocal epifluorescence microscopy. H(2)O(2) caused a rapid increase in cytosolic calcium, which was followed by mitochondrial Ca(2+) loading. Combined mitochondrial uncoupling with full depletion of thapsigargin-sensitive stores abrogated inositol 1,4,5-trisphosphate-mediated calcium release but failed to inhibit H(2)O(2)-induced calcium release, observation that was confirmed in MDCK cells. Prevention of peroxide-induced acidification with a pH clamp was also ineffective, discarding a role for endosomal/lysosomal Ca(2+)/H(+) exchange. Lysosomal integrity was not affected by H(2)O(2). Mature human erythrocytes also reacted to peroxide by releasing intracellular calcium, thus directly demonstrating the cytosolic source. Glutathione depletion markedly sensitized cells to H(2)O(2), an effect opposite to that achieved by DTT. Iron chelation was ineffective. In summary, our results show the existence of a previously unrecognized sulfhydryl-sensitive source of pathogenic calcium in the cytosol of mammalian cells.
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Affiliation(s)
- J Castro
- Centro de Estudios Científicos (CECS), Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile
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20
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Barros LF, Kanaseki T, Sabirov R, Morishima S, Castro J, Bittner CX, Maeno E, Ando-Akatsuka Y, Okada Y. Apoptotic and necrotic blebs in epithelial cells display similar neck diameters but different kinase dependency. Cell Death Differ 2003; 10:687-97. [PMID: 12761577 DOI: 10.1038/sj.cdd.4401236] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Apoptotic and necrotic blebs elicited by H(2)O(2) were compared in terms of dynamics, structure and underlying biochemistry in HeLa cells and Clone 9 cells. Apoptotic blebs appeared in a few minutes and required micromolar peroxide concentrations. Necrotic blebs appeared much later, prior to cell permeabilization, and required millimolar peroxide concentrations. Strikingly, necrotic blebs grew at a constant rate, which was unaffected throughout successive cycles of budding and detachment. At 1 microm diameter, the necks of necrotic and apoptotic blebs were almost identical. ATP depletion was discarded as a major factor for both types of bleb. Inhibition of ROCK-I, MLCK and p38MAPK strongly decreased apoptotic blebbing but had no effect on necrotic blebbing. Taken together, these data suggest the existence of a novel structure of fixed dimensions at the neck of both types of plasma membrane blebs in epithelial cells. However, necrotic blebs can be distinguished from apoptotic blebs in their susceptibility to actomyosin kinase inhibition.
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Affiliation(s)
- L F Barros
- Department of Cell Physiology, National Institute for Physiological Sciences, School of Life Science, Okazaki, Aichi 444-8585, Japan.
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21
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Niemeyer MI, Cid LP, Barros LF, Sepúlveda FV. Modulation of the two-pore domain acid-sensitive K+ channel TASK-2 (KCNK5) by changes in cell volume. J Biol Chem 2001; 276:43166-74. [PMID: 11560934 DOI: 10.1074/jbc.m107192200] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular identity of K(+) channels involved in Ehrlich cell volume regulation is unknown. A background K(+) conductance is activated by cell swelling and is also modulated by extracellular pH. These characteristics are most similar to those of newly emerging TASK (TWIK-related acid-sensitive K(+) channels)-type of two pore-domain K(+) channels. mTASK-2, but not TASK-1 or -3, is present in Ehrlich cells and mouse kidney tissue from where the full coding sequences were obtained. Heterologous expression of mTASK-2 cDNA in HEK-293 cells generated K(+) currents in the absence intracellular Ca(2+). Exposure to hypotonicity enhanced mTASK-2 currents and osmotic cell shrinkage led to inhibition. This occurred without altering voltage dependence and with only slight decrease in pK(a) in hypotonicity but no change in hypertonicity. Replacement with other cations yields a permselectivity sequence for mTASK-2 of K(+) > Rb(+) Cs(+) > NH(4)(+) > Na(+) congruent with Li(+), similar to that for the native conductance (I(K, vol)). Clofilium, a quaternary ammonium blocker of I(K, vol), blocked the mTASK-2-mediated K(+) current with an IC(50) of 25 microm. The presence of mTASK-2 in Ehrlich cells, its functional similarities with I(K, vol), and its modulation by changes in cell volume suggest that this two-pore domain K(+) channel participates in the regulatory volume decrease phenomenon.
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Affiliation(s)
- M I Niemeyer
- Centro de Estudios Cientificos, Av. Arturo Prat 514, Casilla 1469, Valdivia, Chile.
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22
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Abstract
Whether a lethally injured mammalian cell undergoes necrosis or apoptosis may be determined by the early activation of specific ion channels at the cell surface. Apoptosis requires K+ and Cl- efflux, which leads to cell shrinking, an active phenomenon termed apoptotic volume decrease (AVD). In contrast, necrosis has been shown to require Na+ influx through membrane carriers and more recently through stress-activated non-selective cation channels (NSCCs). These ubiquitous channels are kept dormant in viable cells but become activated upon exposure to free-radicals. The ensuing Na+ influx leads to cell swelling, an active response that may be termed necrotic volume increase (NVI). This review focuses on how AVD and NVI become conflicting forces at the beginning of cell injury, on the events that determine irreversibility and in particular, on the ion fluxes that decide whether a cell is to die by necrosis or by apoptosis.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos CECS, Valdivia, Chile.
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23
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Barros LF, Barnes K, Ingram JC, Castro J, Porras OH, Baldwin SA. Hyperosmotic shock induces both activation and translocation of glucose transporters in mammalian cells. Pflugers Arch 2001; 442:614-21. [PMID: 11510895 DOI: 10.1007/s004240100577] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effect of osmotic stress on sugar transport was investigated in Clone 9 epithelial cells, which express the glucose uniporter GLUT1, and in 3T3-L1 adipocytes, which express both GLUT1 and GLUT4. An acute hyperosmotic shock increased the uptake of sugars in both cell types. In Clone 9 cells, this was followed by a regulatory volume increase (RVI) response. Stimulation of transport was rapid and reversible, with half-lives (t 1/2) for stimulation of 2-deoxy-D-glucose uptake of 5.6 +/- 0.9 (n=6) and 22.7 +/- 1.5 (n=4) min for Clone 9 cells and adipocytes respectively. The effect was dose dependent, reaching a maximum at 1.1 osM of 2.9 +/- 0.1-fold (n=3) for Clone 9 cells and 8.2 +/- 0.8-fold (n=3) for adipocytes. In the latter, this stimulation correlated with translocation of the glucose transporter isoform GLUT4 to the cell surface and was not significantly different from that elicited by 160 nM insulin (7.6 +/- 1.2-fold, n=3). The effect of osmotic shock was not, however, influenced by inhibitors of either phosphoinositide 3-kinase (PI 3-kinase) (wortmannin, 250 nM) or of p38 mitogen-activated protein kinase (p38 MAP kinase) (SB203580, 20 microM), which reportedly prevent GLUT4 translocation and/or activation by insulin respectively. These inhibitors also had no effect on the stimulation of transport by osmotic shock in Clone 9 cells. However, in contrast to adipocytes, the effect of osmotic shock on glucose transport in Clone 9 cells reflected primarily a change in the intrinsic activity of cell surface transporters and there was only a minor change in their subcellular distribution as assessed by cell immunostaining or no change as assessed by surface biotinylation. These results indicate that the response of cells to osmotic shock can involve changes both in transporter activity and location. The signal transduction pathways involved include neither PI 3-kinase nor the classical, osmotically-activated component, p38 MAP kinase.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos CECS, Valdivia, Chile.
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24
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Barros LF, Stutzin A, Calixto A, Catalán M, Castro J, Hetz C, Hermosilla T. Nonselective cation channels as effectors of free radical-induced rat liver cell necrosis. Hepatology 2001; 33:114-22. [PMID: 11124827 DOI: 10.1053/jhep.2001.20530] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [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] [Indexed: 01/06/2023]
Abstract
Necrosis, as opposed to apoptosis, is recognized as a nonspecific cell death that induces tissue inflammation and is preceded by cell edema. In non-neuronal cells, the latter has been explained by defective outward pumping of Na(+) caused by metabolic depletion or by increased Na(+) influx via membrane transporters. Here we describe a novel mechanism of swelling and necrosis; namely the influx of Na(+) through oxidative stress-activated nonselective cation channels. Exposure of liver epithelial Clone 9 cells to the free-radical donors calphostin C or menadione induced the rapid activation of an approximately 16-pS nonselective cation channel (NSCC). Blockage of this conductance with flufenamic acid protected the cells against swelling, calcium overload, and necrosis. Protection was also achieved by Gd(3+), an inhibitor of stretch-activated cation channels, or by isosmotic replacement of extracellular Na(+) with N-methyl-D-glucamine. It is proposed that NSCCs, which are ubiquitous although largely inactive in healthy cells, become activated under severe oxidative stress. The ensuing influx of Na(+) initiates a positive feedback of metabolic and electrolytic disturbances leading cells to their necrotic demise.
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Affiliation(s)
- L F Barros
- Instituto de Ciencias Biomédicas Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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25
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Quintanilla RA, Porras OH, Castro J, Barros LF. Cytosolic [Ca(2+)] modulates basal GLUT1 activity and plays a permissive role in its activation by metabolic stress and insulin in rat epithelial cells. Cell Calcium 2000; 28:97-106. [PMID: 10970766 DOI: 10.1054/ceca.2000.0135] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this work was to investigate the role of cytosolic free calcium ([Ca(2+)]c) in the stimulation of GLUT1 by metabolic stress and insulin. Chelation of [Ca(2+)]c with bapta, introduced in rat liver epithelial Clone 9 cells in the acetoxymethyl (AM) form, decreased their basal rate of 2-deoxyglucose uptake in a dose-dependent fashion. Maximal inhibition at 75 microM bapta was by 38 +/- 8% (n = 8). The effect was partially reversed by ionomycin. Basal sugar uptake was also decreased by lowering extracellular [Ca(2+)] in ionomycin-permeabilized cells. Increasing [Ca(2+)]c over its resting level of 168 +/- 32 (n = 27) had no affect on sugar uptake. Chelation of [Ca(2+)]c did not change the abundance of surface GLUT1 and had no significant effect on the affinity of GLUT1 for sugars. In addition, calcium chelation abolished the activation of GLUT1 by azide, arsenate, 2,4-dinitrophenol and insulin. However, [Ca(2+)]c did not increase in the presence of azide. We conclude that [Ca(2+)]c, near or below its resting level, modulates GLUT1 activity over a considerable range and plays a permissive role in the activation of the carrier by metabolic stress and insulin.
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Abstract
Neutrophil accumulation in the first hour of myocardial reperfusion was assessed in dog hearts submitted to ischemia with and without necrosis. In anesthetized dogs, the left anterior descending coronary artery was occluded for 20 min (group IS-20 n = 7) and for 90 min (group IS-90 n = 6). Immediately after reperfusion, 99m Tc-Ceretec (Exametazime-Amersham) labeled neutrophils were injected into a central vein and 60 min later the dogs were killed. The left ventricle was isolated, weighed, and sliced. Six sections, 3 from normal and 3 from reperfused regions, were divided into endocardial and epicardial layers. Myocardial and blood radiometry were used to evaluate the neutrophil accumulation during reperfusion. The differences between leukocyte accumulation in both groups were assessed comparing the ischemic/normal relations in the endocardial and epicardial layers. A second comparison considered myocardium/blood relations to allow the evaluation of differences between remote normal myocardial areas of the two experimental groups. In dogs submitted to 20 min of ischemia, leukocytes accumulated significantly more (P < 0.01) in the reperfused myocardium as compared with the non-ischemic region. The increase occurred both in the endocardial (1.49+/-0.20) and epicardial (1.48+/-0.29) regions. After 90 min ischemia, leukocyte accumulation was more intense and predominant in endocardium where there was a 4-fold (3.97+/-1.28) increase over the non-ischemic region, while in the epicardium this relation was only 2.5-fold (2.56+/-0.98). In the remote non-ischemic myocardium, leukocyte accumulation was greater in dogs submitted to 90 min of ischemia compared to the 20 min group (P < 0.01), without distinction between endocardial and epicardial layers. This accumulation in territories of non-culprit coronary arteries may be related to the blood flow abnormalities and matrix structure changes that occur in these regions during the development of an acute myocardial infarction and its natural repair.
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Affiliation(s)
- L F Barros
- Research Division, Heart Institute (InCor), University of São Paulo Medical School, SP, Brazil
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Affiliation(s)
- L. F. Barros
- Associação Nacional Pró-Saúde Mental; Psicóticos Anônimos
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Abstract
A fluorometric method that allows repeatable measurement of sugar transport rates and parameters in single living cells is presented. Intracellular sugar concentrations were estimated in real time from changes in cell volume that occur secondary to permeation of sugars across the plasma membrane. In turn, the cell volume changes were estimated from variations of intracellular calcein fluorescence measured by confocal microscopy. Using HeLa cells, the assay allowed reproducible measurement of the uptake and exit of D-galactose and 3-O-methyl-D-glucose. The rate of zero-trans uptake (i.e. at an intracellular concentration of zero) of galactose at an extracellular concentration of 200 mM was 0.34+/-0.05 mM/s (n=8). Apparent Vmax and Km for galactose exit were 0.32+/-0.05 mM/s (n=9) and 30+/-7.2 mM (n=9), respectively. The apparent affinity of infinite-trans (i.e. at a very high intracellular concentration) uptake of 3-O-methyl-D-glucose was 3.8+/-0.47 mM (n=8). Galactose uptake was 93+/-8% (n=8) inhibited in the presence of 50 microM phloretin, whereas galactose exit was 96+/-6% (n=5) trans-inhibited by 100 mM 4,6-ethylidine-D-glucose. This technique may help to characterize sugar transport in freshly isolated cells, co-cultures and heterogeneous cell explants. It may also allow available cell microinjection technology to be used to study the regulation of sugar transporters' intrinsic activity. In principle, similar approaches might also be applied in functional studies of other transporters for which non-metabolized substrates are available.
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Affiliation(s)
- L F Barros
- Laboratorio de Fisiopatología Molecular, Programa de Patología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Independencia 1027, Santiago, Chile.
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Barros LF, Young M, Saklatvala J, Baldwin SA. Evidence of two mechanisms for the activation of the glucose transporter GLUT1 by anisomycin: p38(MAP kinase) activation and protein synthesis inhibition in mammalian cells. J Physiol 1997; 504 ( Pt 3):517-25. [PMID: 9401960 PMCID: PMC1159956 DOI: 10.1111/j.1469-7793.1997.517bd.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. Inhibitors of protein synthesis stimulate sugar transport in mammalian cells through activation of plasma membrane GLUT1, the housekeeping isoform of the glucose transporter. However, it has been reported that some of these compounds, in addition to their effect on protein synthesis, also activate protein kinases. 2. In the present study we have explored the role of these two effects on GLUT1 activation. In 3T3-L1 adipocytes and Clone 9 cells, stimulation of sugar transport by puromycin, a translational inhibitor that does not activate kinases, was not detectable until 90 min after exposure. In contrast, stimulation by anisomycin, a potent Jun-NH2-terminal kinase (JNK) agonist, exhibited no lag phase. An intermediate response was observed to emetine and cycloheximide, weak activators of JNK. 3. The potency of anisomycin to stimulate transport acutely (30 min of exposure) was 5- to 10-fold greater than for its chronic stimulation of transport, measured after 4 h of exposure. The stimulation of transport by a low concentration of anisomycin (0.3 microM) was transient, peaked at 30-60 min and it was inhibited (IC50 < 1 microM) by SB203580, which indicates that its mediator is not JNK, but the homologous p38(MAP kinase) (p38(MAPK)). In contrast, the responses to 4 h exposure to 300 microM anisomycin or puromycin were refractory to SB203580. 4. Exposure to anisomycin resulted in rapid activation of p38(MAPK). Activation of both p38(MAPK) and GLUT1 by 0.3 microM anisomycin was cancelled by puromycin. 5. We conclude that the activation of GLUT1 in response to anisomycin includes two components: a delayed component involving translational inhibition and a fast, puromycin-inhibitable component that is secondary to activation of p38(MAPK).
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Affiliation(s)
- L F Barros
- Department of Biochemistry and Molecular Biology, University of Leeds, UK.
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Affiliation(s)
- L F Barros
- Departamento de Medicina Experimental, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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Baldwin SA, Barros LF, Griffiths M, Ingram J, Robbins EC, Streets AJ, Saklatvala J. Regulation of GLUT1 in response to cellular stress. Biochem Soc Trans 1997; 25:954-8. [PMID: 9388580 DOI: 10.1042/bst0250954] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- S A Baldwin
- Department of Biochemistry and Molecular Biology, University of Leeds, U.K
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van den Berghe N, Barros LF, van Mackelenbergh MG, Krans HM. Clostridium botulinum C3 exoenzyme stimulates GLUT4-mediated glucose transport, but not glycogen synthesis, in 3T3-L1 adipocytes--a potential role of rho? Biochem Biophys Res Commun 1996; 229:430-9. [PMID: 8954915 DOI: 10.1006/bbrc.1996.1821] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The signal transduction pathway by which insulin stimulates glucose transport is largely unknown, but a role of PI-3-kinase and small GTP-binding proteins has been proposed. In previous studies we, among many others, excluded a role for the ras/MAP kinase pathway in insulin-mediated glucose transport. In this study we examined a possible role of the small GTP-binding protein rho in this process. Pretreatment of 3T3-L1 adipocytes with botulinum C3 exoenzyme (C3), which is known to ADP-ribosylate and inactivate rho, potently stimulated glucose uptake to a level similar to insulin. Interestingly, glycogen synthesis was not affected by C3 treatment. Insulin stimulates glucose uptake by triggering the translocation of GLUT4, the insulin-sensitive glucose transporter isotype, from an intracellular compartment to the plasma membrane. Similarly, C3-induced glucose uptake was paralleled by GLUT4 translocation. These data point to an important and novel role of the target of C3 (likely rho) in the regulation of GLUT4-mediated glucose transport. Our data suggest that insulin might stimulate glucose uptake through inactivation of rho.
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Affiliation(s)
- N van den Berghe
- Department of Endocrinology, University Hospital Leiden, The Netherlands.
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Abstract
The uptake of glucose into mammalian cells, catalysed by members of the GLUT family of glucose transporters, is regulated by a variety of hormones, growth factors and other agents. In adipocytes, skeletal muscle and heart the principal regulator is the hormone insulin, which rapidly stimulates glucose uptake by bringing about the translocation of the GLUT4 glucose transporter isoform from an intracellular vesicular compartment to the cell surface. Recent studies have implicated the C-terminal hydrophilic region of this protein as being primarily responsible for its insulin-regulated trafficking. In an attempt to identify the protein machinery involved in this trafficking, we have used glutathione S-transferase fusion proteins bearing hydrophilic domains of various GLUT transporters in affinity purification experiments on detergent-solubilized extracts of 3T3-L1 adipocyte intracellular membranes. The C-terminal region of GLUT4 was found specifically to bind a number of polypeptides in these extracts, which are therefore candidates for components of the trafficking machinery. Although these proteins did not bind to the corresponding region of the more widely-distributed GLUT1 glucose transporter isoform, regulation of this transporter also appears to be of physiological importance in some cell types. To study such regulation we have used as a model system the interleukin-3 (IL-3)-dependent haemopoietic cell line IC.DP. These cells express a temperature sensitive mutane of the v-abl tyrosine kinase, whose activation at the permissive temperature permits cell survival in the absence of IL-3 by suppression of apoptosis, although the growth factor is still required for proliferation. Both IL-3 and activation of the kinase were found to stimulate glucose transport by promoting the translocation of GLUT1 to the cell surface. Moreover, inhibition of glucose uptake by addition of transport inhibitors markedly increased the rate of apoptosis, an effect which could be reversed by the provision of alternative energy sources. These observations suggest that the trafficking of GLUT1, regulated by growth factors or oncogenes, may play an important role in the suppression of apoptosis in haemopoietic cells.
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Affiliation(s)
- S A Baldwin
- Department of Biochemistry and Molecular Biology, University of Leeds, UK
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Abstract
The subcellular distributions of the mammalian passive glucose transporter isoforms GLUT1, GLUT3 and GLUT4, in the human placenta, were investigated using isoform-specific anti-peptide antibodies. On western blots of both basal and brush-border plasma membranes isolated from the syncytiotrophoblast, antibodies specific for GLUT1 labelled a broad band (apparent Mr 55,000) that co-migrated with the human erythrocyte GLUT1 glucose transporter. In contrast, no labelling was detectable when blots were probed with antibodies specific for the GLUT3 or GLUT4 isoforms. Densitometric analysis of blots showed that GLUT1 accounts for approximately 90 and 65 per cent of the D-glucose-sensitive cytochalasin B binding sites present in brush-border and basal membranes, respectively. Confocal immunofluorescence microscopy of fixed placental tissue showed that GLUT1 is abundant at both maternal- and fetal-facing surfaces of the syncytiotrophoblast whereas it was undetectable at the fetal capillary endothelium. In parallel experiments, no staining by antibodies against either the GLUT3 or the GLUT4 isoforms was detected in placental tissue. These results indicate that GLUT1 is the major isoform responsible for glucose transfer from mother to fetus. The absence of GLUT4 is consistent with the lack of insulin-sensitive glucose transport across the placenta.
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Affiliation(s)
- L F Barros
- Department of Biochemistry and Molecular Biology, University of Leeds, UK
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Abstract
OBJECTIVE Ion channels play important roles in epithelial transport, but they are difficult to access for conventional electrophysiologic studies in intact placenta. The purpose of this work was to explore the suitability of purified trophoblast plasma membrane as a source of ion channels for reconstitution in artificial lipid membranes. STUDY DESIGN Human placental brush border membranes were purified by differential and gradient centrifugation and fused with small liposomes. Giant liposomes were then generated by a cycle of dehydration and rehydration. These giant liposomes are suitable for electrophysiologic studies and were probed for the presence of active ion channels by the patch-clamp method. RESULTS The results reported here indicate the presence of a high conductance chloride channel showing some similarities with "maxi" chloride channels described in secreting and absorbing epithelia. The channel had a slight outward rectification with conductances of 232 and 300 pS at negative and positive potentials, respectively. CONCLUSIONS For the first time successful reconstitution of a human placental ion channel is achieved in a system suited for electrophysiologic studies. The chloride channel described might play a role in transplacental transport.
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Affiliation(s)
- G Riquelme
- Department of Physiology and Biophysics, School of Medicine, University of Chile, Santiago
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Barros LF, Van den Berghe N, Nixon G, Griffiths M, Van Mackelenbergh M, Ingram J, Baldwin SA. Candidate proteins involved in the targeting of the insulin-sensitive glucose transporter GLUT4 in adipocytes. Biochem Soc Trans 1995; 23:414S. [PMID: 8566302 DOI: 10.1042/bst023414s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- L F Barros
- Department of Biochemistry & Molecular Biology, University of Leeds, U.K
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Barros LF, Marchant RB, Baldwin SA. Dissection of stress-activated glucose transport from insulin-induced glucose transport in mammalian cells using wortmannin and ML-9. Biochem J 1995; 309 ( Pt 3):731-6. [PMID: 7639686 PMCID: PMC1135693 DOI: 10.1042/bj3090731] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The signaling pathways responsible for the activation of glucose transport by insulin and by metabolic stress in mammalian cells were studied in Clone 9 cells and 3T3-L1 adipocytes. Exposure of both cell types to azide or insulin markedly increased their glucose uptake capacity (Vmax.) without affecting their apparent affinity for glucose (Km). The effects of azide and insulin were not additive. Wortmannin, a selective inhibitor of phosphatidylinositol (PI) 3-kinase, did not affect stimulation of transport by azide but inhibited insulin-induced glucose transport with a Ki of < 10 nM. ML-9, a putative mitogen-activated protein kinase inhibitor, was equipotent in its inhibition of azide- and insulin-stimulated glucose transport. These findings suggest that multiple signalling cascades are involved in the stimulation of glucose transport in mammalian cells and that PI 3-kinase, an essential link in the pathway by which insulin stimulates glucose transport, is not necessary for the activation of glucose uptake by metabolic stress.
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Affiliation(s)
- L F Barros
- Department of Biochemistry and Molecular Biology, University of Leeds, U.K
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Abstract
The effects of plasma magnesium elevation on myocardial necrosis were tested in anesthetized dogs submitted to left anterior descending coronary artery occlusion and reperfusion. Eighteen dogs were treated with magnesium sulfate soon after the coronary occlusion in order to treble the plasma concentration, while 18 others remained as controls. The treatment determined only slight reductions in the heart rate and in the arterial blood pressure, from the beginning to the end of the experiment. The percent necrosis of the ischemic myocardium was determined by staining and weighting the normal, the preserved and the necrotic areas. Necrosis was noticed in 63.7 +/- 16.8% and 44.2 +/- 20.8% of the risk area in the control and treated groups, respectively (P = 0.004). It is concluded that the treatment has protected the ischemic/reperfused myocardium reducing the final necrosis of the risk area by about 30%. This effect may be ascribed to the hemodynamic changes determined by magnesium sulfate infusion as well as to metabolic actions during ischemia and reperfusion.
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Affiliation(s)
- L F Barros
- Divisão de Pesquisa Experimental, Instituto do Coração (INCOR), Faculdade de Medicina de São Paulo, Universidade de São Paulo, Brazil
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Barros LF, Yudilevich DL, Jarvis SM, Beaumont N, Young JD, Baldwin SA. Immunolocalisation of nucleoside transporters in human placental trophoblast and endothelial cells: evidence for multiple transporter isoforms. Pflugers Arch 1995; 429:394-9. [PMID: 7761263 DOI: 10.1007/bf00374155] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Polyclonal antibodies raised against the human erythrocyte nucleoside transporter were used to investigate the distribution of the nucleoside transporters in the placenta. Immunoblots of brush-border membranes isolated from the human syncytiotrophoblast revealed a cross-reactive species that co-migrated with the erythrocyte nucleoside transporter as a broad band of apparent M(r) 55,000. In contrast, no labelling was detected in basal membranes containing a similar number of equilibrative nucleoside transporters as assessed by nitrobenzylthioinosine (NBMPR)-binding. The absence of cross-reactive epitopes in basal membranes and their presence in brush-border membranes was confirmed by confocal immunofluorescence microscopy. These results suggest that at least two isoforms of the NBMPR-sensitive nucleoside transporter are present in the human placenta. The lumenal surfaces of fetal capillaries, small placental vessels and umbilical vein were also strongly labelled by the antibody, a finding that suggests that the high fetal-placental adenosine uptake previously reported is due to endothelial transporters.
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Affiliation(s)
- L F Barros
- Departmento of Fisiología y Biofísica, Universidad de Chile, Santiago
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Barros LF. Hypoxanthine transport in the guinea pig and human placenta is a carrier-mediated process that does not involve nucleoside transporters. Am J Obstet Gynecol 1994; 171:111-7. [PMID: 8030685 DOI: 10.1016/s0002-9378(94)70086-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE The purpose of this study was to characterize the mechanisms involved in the placental clearance of hypoxanthine. STUDY DESIGN Uptake of isotope-labeled compounds was measured in the in situ perfused guinea pig placenta and in membrane vesicles isolated from the human syncytiotrophoblast. RESULTS In the guinea pig hypoxanthine uptake (from the fetal circulation) proceeded by a saturable (Michaelis constant approximately 90 mumol/L), sodium-dependent mechanism that was inhibited by 19 mmol/L papaverine but not by 10 mumol/L nitrobenzylthioinosine or 10 mmol/L uridine. Uridine uptake was blocked by nitrobenzylthioinosine but not by papaverine or 4 mmol/L hypoxanthine. In human brush-border (maternal-facing) membrane vesicles hypoxanthine influx was sodium independent and best fitted to a saturable (Michaelis constant 290 +/- 45 mumol/L) plus a linear component. Saturable influx was blocked by papaverine but not by nitrobenzylthioinosine. Uridine uptake was not affected by 4 mmol/L hypoxanthine. Mediated hypoxanthine uptake by human basal (fetal-facing) membrane vesicles was not detected. CONCLUSION At both placental blood-tissue interfaces hypoxanthine transport occurs through specific mechanisms that are different from the nucleoside transporters.
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Affiliation(s)
- L F Barros
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Chile, Santiago
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Barros LF, Beaumont N, Jarvis SM, Young JD, Henderson PJ, Yudilevich DL, Thrasivoulou C, Baldwin SA. Nucleoside transporters in human placenta. Biochem Soc Trans 1992; 20:244S. [PMID: 1426539 DOI: 10.1042/bst020244s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Barros LF, Bustamante JC, Yudilevich DL, Jarvis SM. Adenosine transport and nitrobenzylthioinosine binding in human placental membrane vesicles from brush-border and basal sides of the trophoblast. J Membr Biol 1991; 119:151-61. [PMID: 1904498 DOI: 10.1007/bf01871414] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The nucleoside transport activity of human placental syncytiotrophoblast brush-border and basal membrane vesicles was compared. Adenosine and uridine were taken up into an osmotically active space. Adenosine was rapidly metabolized to inosine, metabolism was blocked by preincubating vesicles with 2'-deoxycoformycin, and subsequent adenosine uptake studies were performed in the presence of 2'-deoxycoformycin. Adenosine influx by brush-border membrane vesicles was fitted to a two-component system consisting of a saturable system with apparent Michaelis-Menten kinetics (apparent Km approx. 150 microM) and a linear component. Adenosine uptake by the saturable system was blocked by nitrobenzylthioinosine (NBMPR), dilazep, dipyridamole and other nucleosides. Inhibition by NBMPR was associated with high-affinity binding of NBMPR to the brush-border membrane vesicles (apparent Kd 0.98 +/- 0.21 nM). Binding of NBMPR to these sites was blocked by adenosine, inosine, uridine, thymidine, dilazep and dipyridamole, and the respective apparent Ki values were 0.23 +/- 0.012, 0.36 +/- 0.035, 0.78 +/- 0.1, 0.70 +/- 0.12 (mM), and 0.12 and 4.2 +/- 1.4 (nM). In contrast, adenosine influx by basal membrane vesicles was low (less than 10% of the rate observed with brush-border membrane vesicles under similar conditions), and hence no quantitative studies of adenosine uptake could be performed with these vesicles. Nevertheless, high-affinity NBMPR binding sites were demonstrated in basal membrane vesicles with similar properties to those in brush-border membrane vesicles (apparent Kd 1.05 +/- 0.13 nM and apparent Ki values for adenosine, inosine, uridine, thymidine, dilazep and dipyridamole of 0.14 +/- 0.045, 0.54 +/- 0.046, 1.26 +/- 0.20, 1.09 +/- 0.18 mM and 0.14 and 3.7 +/- 0.5 nM, respectively). Exposure of both membrane vesicles to UV light in the presence of [3H]NBMPR resulted in covalent labeling of a membrane protein(s) with a broad apparent Mr on SDS gel electropherograms of 77,000-45,000, similar to that previously reported for many other tissues, including human erythrocytes. We conclude that the maternal (brush-border) and fetal (basal) surfaces of the human placental syncytiotrophoblast possess broad-specificity, facilitated-diffusion, NBMPR-sensitive nucleoside transporters.
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Affiliation(s)
- L F Barros
- Biomedical Sciences Division, King's College London, United Kingdom
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Affiliation(s)
- D L Yudilevich
- Biomedical Sciences Division, King's College, University of London, U.K
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da-Luz PL, Leite JJ, Barros LF, Dias-Neto A, Zanarco EL, Pileggi FJ. Experimental myocardial infarction: effect of methylprednisolone on myocardial blood flow after reperfusion. Braz J Med Biol Res 1982; 15:355-60. [PMID: 7184524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The effect of methylprednisolone on the distribution of myocardial flow during ischemia and after reperfusion was determined in 10 treated and 11 control dogs. Methylprednisolone, 30 mg/kg, was administered iv after occlusion. Transmural blood flow and the endo/epicardial ratio in the normal and ischemic zones was measured by injecting 141Ce- and 85Sr-labelled microspheres after 90 min of ischemia and 30 min after reperfusion, respectively. During ischemia, transmural blood flow (ml g-1 min-1) in the ischemic zone was higher in treated animals than in controls (0.25 +/- 0.04 vs 0.15 +/- 0.03; P less than 0.05) but not different in the normal zone for both groups (1.36 +/- 0.14 vs 1.15 +/- 0.10; P greater than 0.05). The endo/epicardial ratio of the ischemic zone was low but similar for both groups during ischemia (0.43 +/- 0.07 vs 0.40 +/- 0.09; P greater than 0.05). After reperfusion, transmural blood flow increased significantly in treated (0.25 +/- 0.13 vs 1.36 +/- 0.13; P less than 0.0005) as well as in control animals (0.15 +/- 0.03 vs 1.63 +/- 0.14; P greater than 0.0005), reaching similar values (1.36 +/- 0.13 vs 1.63 +/- 0.14; P greater than 0.05). The endo/epicardial ratio also increased during reperfusion in both treated (0.43 +/- 0.07 vs 1.12 +/- 0.12; P less than 0.0005) and control animals (0.40 +/- 0.90 vs 1.03 +/- 0.19; P less than 0.025). These data show that although methylprednisolone-treated dogs had higher myocardial blood flow during ischemia, after reperfusion the increase in flow in the ischemic zone of treated and control dogs was of the same magnitude.
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Cunha RG, Quintais AC, Barros LF. [Infectivity of mumps virus to chicks and its relation to Newcastle disease virus]. Rev Bras Biol 1980; 40:125-30. [PMID: 7403588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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