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Barnett RL, Austermann J, Dyer B, Telfer MW, Barlow NLM, Boulton SJ, Carr AS, Creel RC. Constraining the contribution of the Antarctic Ice Sheet to Last Interglacial sea level. Sci Adv 2023; 9:eadf0198. [PMID: 37406130 DOI: 10.1126/sciadv.adf0198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 06/05/2023] [Indexed: 07/07/2023]
Abstract
Polar temperatures during the Last Interglacial [LIG; ~129 to 116 thousand years (ka)] were warmer than today, making this time period an important testing ground to better understand how ice sheets respond to warming. However, it remains debated how much and when the Antarctic and Greenland ice sheets changed during this period. Here, we present a combination of new and existing absolutely dated LIG sea-level observations from Britain, France, and Denmark. Because of glacial isostatic adjustment (GIA), the LIG Greenland ice melt contribution to sea-level change in this region is small, which allows us to constrain Antarctic ice change. We find that the Antarctic contribution to LIG global mean sea level peaked early in the interglacial (before 126 ka), with a maximum contribution of 5.7 m (50th percentile, 3.6 to 8.7 m central 68% probability) before declining. Our results support an asynchronous melt history over the LIG, with an early Antarctic contribution followed by later Greenland Ice Sheet mass loss.
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Affiliation(s)
- Robert L Barnett
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
- Département de biologie, chimie et géographie et Centre d'études nordiques, Université du Québec à Rimouski, Rimouski, QC, Canada
| | | | - Blake Dyer
- School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada
| | - Matt W Telfer
- School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth, UK
| | | | - Sarah J Boulton
- School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth, UK
| | - Andrew S Carr
- School of Geography, Geology and the Environment, University of Leicester, Leicester, UK
| | - Roger C Creel
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
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2
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Whittle A, Barnett RL, Charman DJ, Gallego-Sala AV. Low-salinity transitions drive abrupt microbial response to sea-level change. Ecol Lett 2021; 25:17-25. [PMID: 34708510 DOI: 10.1111/ele.13893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 01/22/2021] [Revised: 07/15/2021] [Accepted: 07/29/2021] [Indexed: 11/30/2022]
Abstract
The salinisation of many coastal ecosystems is underway and is expected to continue into the future because of sea-level rise and storm intensification brought about by the changing climate. However, the response of soil microbes to increasing salinity conditions within coastal environments is poorly understood, despite their importance for nutrient cascading, carbon sequestration and wider ecosystem functioning. Here, we demonstrate deterioration in the productivity of a top-tier microbial group (testate amoebae) with increasing coastal salinity, which we show to be consistent across phylogenetic groups, salinity gradients, environment types and latitude. Our results show that microbial changes occur in the very early stages of marine inundation, presaging more radical changes in soil and ecosystem function and providing an early warning of coastal salinisation that could be used to improve coastal planning and adaptation.
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Affiliation(s)
- Alex Whittle
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.,British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
| | - Robert L Barnett
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.,Département de biologie, chimie et géographie et Centre d'études nordiques, Université du Québec à Rimouski, Rimouski, Canada
| | - Dan J Charman
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Angela V Gallego-Sala
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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3
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Barnett RL, Charman DJ, Johns C, Ward SL, Bevan A, Bradley SL, Camidge K, Fyfe RM, Gehrels WR, Gehrels MJ, Hatton J, Khan NS, Marshall P, Maezumi SY, Mills S, Mulville J, Perez M, Roberts HM, Scourse JD, Shepherd F, Stevens T. Nonlinear landscape and cultural response to sea-level rise. Sci Adv 2020; 6:6/45/eabb6376. [PMID: 33148641 PMCID: PMC7673675 DOI: 10.1126/sciadv.abb6376] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Rising sea levels have been associated with human migration and behavioral shifts throughout prehistory, often with an emphasis on landscape submergence and consequent societal collapse. However, the assumption that future sea-level rise will drive similar adaptive responses is overly simplistic. While the change from land to sea represents a dramatic and permanent shift for preexisting human populations, the process of change is driven by a complex set of physical and cultural processes with long transitional phases of landscape and socioeconomic change. Here, we use reconstructions of prehistoric sea-level rise, paleogeographies, terrestrial landscape change, and human population dynamics to show how the gradual inundation of an island archipelago resulted in decidedly nonlinear landscape and cultural responses to rising sea levels. Interpretation of past and future responses to sea-level change requires a better understanding of local physical and societal contexts to assess plausible human response patterns in the future.
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Affiliation(s)
- Robert L Barnett
- Geography, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK.
- Département de biologie, chimie et géographie & Centre for Northern Studies (CEN), Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - Dan J Charman
- Geography, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK
| | - Charles Johns
- Heritage Consultant, Sunset, Trewennack, Helston, Cornwall TR13 0PL, UK
| | - Sophie L Ward
- Centre for Applied Marine Sciences, School of Ocean Sciences, Bangor University, Menai Bridge, Isle of Anglesey LL59 5AB, UK
| | - Andrew Bevan
- UCL Institute of Archaeology, University College London, 31-34 Gordon Square, London WC1H 0PY, UK
| | - Sarah L Bradley
- Department of Geography, University of Sheffield, Winter Street, Sheffield S3 7ND, UK
| | - Kevin Camidge
- Cornwall and Isles of Scilly Maritime Archaeology Society, 10 Tolver Place, Penzance TR18 2AD, UK
| | - Ralph M Fyfe
- School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - W Roland Gehrels
- Department of Environment and Geography, University of York, Heslington, York YO10 5NG, UK
| | - Maria J Gehrels
- Department of Environment and Geography, University of York, Heslington, York YO10 5NG, UK
| | - Jackie Hatton
- Geography, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK
| | - Nicole S Khan
- Department of Earth Sciences, University of Hong Kong, James Lee Building, Pokfulam Road, Hong Kong, Hong Kong
| | - Peter Marshall
- Policy and Evidence, Historic England, Cannon Bridge House, 25 Dowgate Hill, London EC4R 2YA, UK
| | - S Yoshi Maezumi
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, Netherlands
| | - Steve Mills
- School of History, Archaeology and Religion, Cardiff University, John Percival Building, Colum Drive, Cardiff CF10 3EU, UK
| | - Jacqui Mulville
- School of History, Archaeology and Religion, Cardiff University, John Percival Building, Colum Drive, Cardiff CF10 3EU, UK
| | - Marta Perez
- Geography, Royal Holloway, University of London, Egham TW20 0EX, UK
| | - Helen M Roberts
- Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth SY23 3DB, UK
| | - James D Scourse
- Geography, University of Exeter, Peter Lanyon Building, Treliever Road, Penryn TR10 9FE, UK
| | - Francis Shepherd
- Cornwall and Isles of Scilly Historic Environment Record, Cornwall Council, Kresen Kernow, Little Vauxhall, Redruth, Cornwall TR15 1AS, UK
| | - Todd Stevens
- Colossus, Pilot's Retreat, St Mary's, Isles of Scilly TR21 0PB, UK
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Maezumi SY, Alves D, Robinson M, de Souza JG, Levis C, Barnett RL, Almeida de Oliveira E, Urrego D, Schaan D, Iriarte J. The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon. Nat Plants 2018; 4:540-547. [PMID: 30038410 PMCID: PMC6119467 DOI: 10.1038/s41477-018-0205-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 06/15/2018] [Indexed: 05/29/2023]
Abstract
The legacy of pre-Columbian land use in the Amazonian rainforest is one of the most controversial topics in the social1-10 and natural sciences11,12. Until now, the debate has been limited to discipline-specific studies, based purely on archaeological data8, modern vegetation13, modern ethnographic data3 or a limited integration of archaeological and palaeoecological data12. The lack of integrated studies to connect past land use with modern vegetation has left questions about the legacy of pre-Columbian land use on the modern vegetation composition in the Amazon, unanswered11. Here, we show that persistent anthropogenic landscapes for the past 4,500 years have had an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. We found an abrupt enrichment of edible plant species in fossil lake and terrestrial records associated with pre-Columbian occupation. Our results demonstrate that, through closed-canopy forest enrichment, limited clearing for crop cultivation and low-severity fire management, long-term food security was attained despite climate and social changes. Our results suggest that, in the eastern Amazon, the subsistence basis for the development of complex societies began ~4,500 years ago with the adoption of polyculture agroforestry, combining the cultivation of multiple annual crops with the progressive enrichment of edible forest species and the exploitation of aquatic resources. This subsistence strategy intensified with the later development of Amazonian dark earths, enabling the expansion of maize cultivation to the Belterra Plateau, providing a food production system that sustained growing human populations in the eastern Amazon. Furthermore, these millennial-scale polyculture agroforestry systems have an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. Together, our data provide a long-term example of past anthropogenic land use that can inform management and conservation efforts in modern Amazonian ecosystems.
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Affiliation(s)
- S Yoshi Maezumi
- Department of Archaeology, College of Humanities, University of Exeter, Exeter, UK.
| | - Daiana Alves
- Department of Archaeology, College of Humanities, University of Exeter, Exeter, UK
| | - Mark Robinson
- Department of Archaeology, College of Humanities, University of Exeter, Exeter, UK
| | | | - Carolina Levis
- Programa de Pós-Graduação em Ecologia, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Brazil
- Forest Ecology and Management Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Robert L Barnett
- Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | - Dunia Urrego
- Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Denise Schaan
- Department of Anthropology, Federal University of Pará, Belém, Brazil
| | - José Iriarte
- Department of Archaeology, College of Humanities, University of Exeter, Exeter, UK
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5
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Keast VJ, Barnett RL, Cortie MB. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds. J Phys Condens Matter 2014; 26:305501. [PMID: 25001413 DOI: 10.1088/0953-8984/26/30/305501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications.
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Affiliation(s)
- V J Keast
- School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan NSW 2308, Australia
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Hartman AZ, Jouzi M, Barnett RL, Xu JM. Theoretical and experimental studies of carbon nanotube electromechanical coupling. Phys Rev Lett 2004; 92:236804. [PMID: 15245185 DOI: 10.1103/physrevlett.92.236804] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2003] [Indexed: 05/24/2023]
Abstract
We present an investigation into electromechanical coupling in carbon nanotubes by focusing on phonon frequency shifts as a result of charge injection. A nearest-neighbor, tight-binding theoretical model is accompanied by a computational explication carried out using the Vienna ab initio simulation package density functional theory code. Raman spectroscopic measurements of the electromechanic couplings under varied but controlled charge injection conditions are also carried out, and the close agreement between the model results and the measured Raman peak shifts suggests that geometrical changes of charged carbon nanotubes previously observed or speculated in different experiments can indeed originate from the simple quantum effects described herein.
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Affiliation(s)
- A Z Hartman
- Division of Engineering and Department of Physics, Brown University, Box D, Providence, Rhode Island 02912, USA
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8
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Sher L, Barnett RL. Light-therapy-induced hot flushes in a patient with seasonal affective disorder. J Psychiatry Neurosci 1999; 24:249-50. [PMID: 10354661 PMCID: PMC1189017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
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9
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Postolache TT, Hardin TA, Myers FS, Turner EH, Yi LY, Barnett RL, Matthews JR, Rosenthal NE. Greater improvement in summer than with light treatment in winter in patients with seasonal affective disorder. Am J Psychiatry 1998; 155:1614-6. [PMID: 9812130 DOI: 10.1176/ajp.155.11.1614] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [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: 11/30/2022]
Abstract
OBJECTIVE The authors sought to compare the degree of mood improvement after light treatment with mood improvement in the subsequent summer in patients with seasonal affective disorder. METHOD By using the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale, the authors rated 15 patients with seasonal affective disorder on three occasions: during winter when the patients were depressed, during winter following 2 weeks of light therapy, and during the following summer. They compared the three conditions by using Friedman's analysis of variance and the Wilcoxon signed ranks test. RESULTS The patients' scores on the depression scale were significantly higher after 2 weeks of light therapy in winter than during the following summer. CONCLUSIONS Light treatment for 2 weeks in winter is only partially effective when compared to summer. Further studies will be necessary to assess if summer's light or other factors are the main contributors to this difference.
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Affiliation(s)
- T T Postolache
- Clinical Psychobiology Branch, NIMH, Bethesda, MD 20892, USA.
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10
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Neumeister A, Turner EH, Matthews JR, Postolache TT, Barnett RL, Rauh M, Vetticad RG, Kasper S, Rosenthal NE. Effects of tryptophan depletion vs catecholamine depletion in patients with seasonal affective disorder in remission with light therapy. Arch Gen Psychiatry 1998; 55:524-30. [PMID: 9633671 DOI: 10.1001/archpsyc.55.6.524] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Although hypotheses about the therapeutic mechanism of action of light therapy have focused on serotonergic mechanisms, the potential role, if any, of catecholaminergic pathways has not been fully explored. METHODS Sixteen patients with seasonal affective disorder who had responded to a standard regimen of daily 10000-lux light therapy were enrolled in a double-blind, placebo-controlled, randomized crossover study. We compared the effects of tryptophan depletion with catecholamine depletion and sham depletion. Ingestion of a tryptophan-free amino acid beverage plus amino acid capsules was used to deplete tryptophan. Administration of the tyrosine hydroxylase inhibitor alpha-methyl-paratyrosine was used to deplete catecholamines. Diphenhydramine hydrochloride was used as an active placebo during sham depletion. The effects of these interventions were evaluated with measures of depression, plasma tryptophan levels, and plasma catecholamine metabolites. RESULTS Tryptophan depletion significantly decreased plasma total and free tryptophan levels. Catecholamine depletion significantly decreased plasma 3-methoxy-4-hydroxyphenylethyleneglycol and homovanillic acid levels. Both tryptophan depletion and catecholamine depletion, compared with sham depletion, induced a robust increase (P<.001, repeated-measures analysis of variance) in depressive symptoms as measured with the Hamilton Depression Rating Scale, Seasonal Affective Disorder Version. CONCLUSIONS The beneficial effects of light therapy in the treatment of seasonal affective disorder are reversed by both tryptophan depletion and catecholamine depletion. These findings confirm previous work showing that serotonin plays an important role in the mechanism of action of light therapy and provide new evidence that brain catecholaminergic systems may also be involved.
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Affiliation(s)
- A Neumeister
- National Institute of Mental Health, Clinical Psychobiology Branch, Bethesda, MD, USA.
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11
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Rosenthal NE, Mazzanti CM, Barnett RL, Hardin TA, Turner EH, Lam GK, Ozaki N, Goldman D. Role of serotonin transporter promoter repeat length polymorphism (5-HTTLPR) in seasonality and seasonal affective disorder. Mol Psychiatry 1998; 3:175-7. [PMID: 9577843 DOI: 10.1038/sj.mp.4000360] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.3] [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: 02/07/2023]
Abstract
Seasonal variations in mood and behavior (seasonality) and seasonal affective disorder (SAD) have been attributed to seasonal fluctuations in brain serotonin (5-HT). the short (s), as opposed to the long (l), allele of the 5-HT transporter linked polymorphism (5-HTTLPR) has been associated with neuroticism and depression. We hypothesized that this short allele would also be associated with SAD and with higher levels of seasonality. Ninety-seven SAD patients and 71 non-seasonal healthy controls with low seasonality levels were genotyped for 5-HTTLPR and compared statistically. Patients with SAD were less likely to have the l/l genotype (27.8% vs 47.9%; P < 0.01) and more likely to have the s allele (44.8% vs 32.4%; P < 0.02) as compared to controls. The three 5-HTTLPR genotypes were also differentially distributed in patients and controls (P < 0.03). The SAD patients with the l/l genotype had a lower mean seasonality score than did patients with the other two genotypes (mean +/- s.d. = 15.3 +/- 2.8 vs 17.1 +/- 3.4 respectively; P < 0.02). The 5-HTTLPR short allele contributes to the trait of seasonality and is a risk factor for SAD, providing further evidence for a relationship between genetic variation in the 5-HT transporter (5-HTT) and behavior.
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Affiliation(s)
- N E Rosenthal
- National Institute of Mental Health, Clinical Psychobiology Branch, Bethesda, MD 20892-1390, USA.
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12
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Barnett RL, Ruffini L, Ramsammy L, Pasmantier R, Friedlaender MM, Nord EP. cGMP antagonizes angiotensin-mediated phosphatidylcholine hydrolysis and C kinase activation in mesangial cells. Am J Physiol 1995; 268:C376-81. [PMID: 7864076 DOI: 10.1152/ajpcell.1995.268.2.c376] [Citation(s) in RCA: 13] [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] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previous studies from this laboratory have shown that in cultured rat mesangial cells (MC), angiotensin II (ANG II) mediates its effects via activation of phosphatidylinositol-specific phospholipase C (PI-PLC) and phosphatidylcholine-specific phospholipase C (PC-PLC) and phospholipase D (PC-PLD). In addition, guanosine 3',5'-cyclic monophosphate (cGMP)-elevating maneuvers that stimulate particulate and soluble guanylate cyclase [atrial natriuretic factor (ANF) and sodium nitroprusside (SNP), respectively] antagonize ANG II-mediated PI-PLC activation. The current study explored whether cGMP impairs ANG II-mediated PC-PLC and PLD activity. The ANG II-stimulated release of the water-soluble metabolites of PC breakdown (phosphorylcholine and choline) was blocked by ANF and SNP. ANG II-stimulated phosphatidic acid and phosphatidylethanol formation were significantly reduced by ANF and SNP, confirming that cGMP blunted PLD activity. The inhibitory effect of cGMP on PLD could be reversed by N-(2-[methylamino]ethyl)-5-isoquinolinesulfonamide, a blocker of cGMP-dependent protein kinase. In parallel experiments, ANF and SNP abrogated sustained diacylglycerol (DAG) accumulation derived from ANG II stimulation of PC hydrolysis, confirming that cGMP diminished PC-PLC activity. Inhibition of PC-derived DAG accumulation by cGMP was associated with a concomitant decrement in ANG II-mediated translocation of protein kinase C (PKC) activity from the cytosol to the membrane. In summary, in MC, cGMP antagonizes ANG II-mediated PC hydrolysis, DAG formation, and PKC activation. We propose that cGMP-mediated inhibition of phospholipid metabolism and PKC translocation plays an important role in MC vasorelaxation.
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Affiliation(s)
- R L Barnett
- Department of Medicine, School of Medicine, State University of New York at Stony Brook 11794
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Barnett RL, Ruffini L, Hart D, Mancuso P, Nord EP. Mechanism of endothelin activation of phospholipase A2 in rat renal medullary interstitial cells. Am J Physiol 1994; 266:F46-56. [PMID: 8304484 DOI: 10.1152/ajprenal.1994.266.1.f46] [Citation(s) in RCA: 11] [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] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous studies from this laboratory have demonstrated that endothelin-1 (ET) stimulates phosphatidylinositol (PI) hydrolysis, activates dihydropyridine-insensitive Ca2+ channels, and promotes prostaglandin E2 (PGE2) accumulation in cultured rat renal medullary interstitial cells (RMIC). The mechanism whereby ET augments PGE2 production was explored in the current study. ET-evoked PGE2 accumulation proceeded independent of large increments in cytosolic free Ca2+ concentration ([Ca2+]i), derived from either extracellular or intracellular sources. Chelation of intracellular Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid eliminated ET-evoked PGE2 production, indicating that eicosanoid production was nonetheless a Ca(2+)-requiring process. Nanomolar concentrations of phorbol 12-myristate 13-acetate (PMA) alone did not stimulate PGE2 production, nor did PMA alter ET-stimulated PGE2 accumulation. Furthermore, downregulation of protein kinase C (PKC) by prolonged exposure of cells to PMA did not mitigate ET-mediated PGE2 production, demonstrating that PKC stimulation was not required for PGE2 production. ET stimulated PGE2 accumulation despite PI-specific phospholipase C (PI-PLC) inhibition by nanomolar concentrations of PMA, indicating that eicosanoid production was not a downstream event of PI hydrolysis. ET stimulated arachidonic acid metabolite release in parallel with a loss of label from membrane phospholipids. Phosphatidylethanolamine was the preferred substrate for ET-mediated activation of phospholipase A2 (PLA2). Immunocytochemical studies including immunostaining, immunoblotting, and immunoprecipitation confirmed the presence of cytosolic PLA2 (cPLA2) in RMIC. In summary, ET stimulation of PGE2 production in RMIC is mediated via agonist activation of cPLA2 independent of activation of PI-PLC, suggesting direct coupling to the ET receptor. Constitutive levels of [Ca2+]i rather than abrupt increments in [Ca2+]i are sufficient for activation of this receptor-effector system, with no obligatory requirement for PKC.
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Affiliation(s)
- R L Barnett
- Department of Medicine, School of Medicine, State University of New York at Stony Brook 11794
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Barnett RL, Ruffini L, Ramsammy L, Pasmantier R, Friedlaender MM, Nord EP. Angiotensin-mediated phosphatidylcholine hydrolysis and protein kinase C activation in mesangial cells. Am J Physiol 1993; 265:C1100-8. [PMID: 8238300 DOI: 10.1152/ajpcell.1993.265.4.c1100] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Angiotensin II (ANG II) in mesangial cells (MC) promotes phosphatidylinositol (PI) hydrolysis resulting in diacylglycerol (DAG)-mediated increases in protein kinase C (PKC) activity. The paucity of MC inositol lipid prompted us to consider whether phosphatidylcholine (PC) could sustain DAG formation. ANG II released choline and increased phosphatidylethanol (PEt) via PC-phospholipase D (PC-PLD). ANG II also stimulated phosphorylcholine consequent to PC-phospholipase C (PC-PLC) activation. ANG II-mediated PC hydrolysis augmented DAG for 30 min. PC breakdown was influenced by extracellular Ca2+, because Ni2+ partially inhibited ANG II-induced PEt and obliterated agonist-mediated DAG formation. The consequence of Ca2+ modulation of PC metabolism was investigated by measuring PKC activity. Ni2+ had no effect on early (PI-associated) activation by ANG II at 90 s but obviated translocation from cytosol to the membrane at 10 min. The pathway responsible for PC-associated DAG was studied in PKC downregulated cells. Whereas downregulation prevented PLD-mediated PEt elevation, ANG II-stimulated DAG formation in myristate-labeled cells was unaltered, indicating PC-PLC activation. In summary, ANG II stimulates PC-PLD and PC-PLC in MC. PC-PLD is tightly regulated by PKC, whereas PC-PLC is stringently controlled by extracellular Ca2+. ANG II mediated PC breakdown principally via PC-PLC provides a mechanism for maintaining elevated DAG levels and PKC activation.
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Affiliation(s)
- R L Barnett
- Department of Medicine, School of Medicine, State University of New York at Stony Brook 11794
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Friedlaender MM, Jain D, Ahmed Z, Hart D, Barnett RL, Nord EP. Endothelin activation of phospholipase D: dual modulation by protein kinase C and Ca2+. Am J Physiol 1993; 264:F845-53. [PMID: 8498538 DOI: 10.1152/ajprenal.1993.264.5.f845] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous work from this laboratory has identified an endothelin (ET) type A (ETA) receptor on cultured rat renal medullary interstitial cells (RMIC), coupled to phosphatidylinositol-specific phospholipase C (PI-PLC), dihydropyridine-insensitive receptor-operated Ca2+ channels, and phospholipase A2. The current studies explored a role for ET stimulation of phosphatidylcholine-specific phospholipase D (PC-PLD) in intracellular signaling of this cell type. ET stimulated PLD activation, as measured by phosphatidic acid (PA) or phosphatidylethanol (PEt) accumulation, in a time- and concentration-dependent manner. Inhibition of diacylglycerol (DAG) kinase by ethylene glycol dioctanoate or 6-(2)4-[(4-fluorophenyl)-phenylmethylene]-1-piperadinyl]ethy l-7-methyl-5H - thiaxolo-[3,2-alpyrimidin]-5-one (R 59022) failed to blunt PA accumulation, indicating that PLD, and not DAG, was the source of PA. Inhibition of PA phosphohydrolase (PAP) by propranolol increased late accumulation of PA, suggesting that the prevailing metabolic flow was in the direction of PA to DAG. Phorbol 12-myristate 13-acetate (PMA) augmented ET-evoked PEt accumulation, whereas downregulation of protein kinase C (PKC) obviated agonist-induced PEt production. PMA augmentation of PLD activity proceeded independent of cytosolic free Ca2+ concentration. Ca2+ derived from either intracellular or extracellular sources enhanced ET-related PEt accumulation but was without effect in PKC-downregulated cells. Collectively, these observations indicate that ET stimulates PLD production in RMIC. PKC is the major regulator of this process, with Ca2+ playing a secondary, modulatory role. In addition, these data suggest that PC-PLD is coupled to the ETA receptor.
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Affiliation(s)
- M M Friedlaender
- Department of Medicine, School of Medicine, Hadassah University Hospital, Jerusalem, Israel
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Andrykowski MA, Altmaier EM, Barnett RL, Burish TG, Gingrich R, Henslee-Downey PJ. Cognitive dysfunction in adult survivors of allogeneic marrow transplantation: relationship to dose of total body irradiation. Bone Marrow Transplant 1990; 6:269-76. [PMID: 2085701] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Bone marrow transplant (BMT) patients are exposed to several potential sources of neurologic damage including the neurotoxicity of pre-BMT preparative regimens. The latter generally include a combination of total body irradiation (TBI) and high-dose chemotherapy. Cognitive functioning in 30 adult allogeneic BMT patients (mean of 47 months post-BMT) treated for either acute or chronic leukemia was assessed by two standardized self-report questionnaires. Consistent with hypothesis, results of both univariate and multivariate analyses indicated that increased dose of TBI was associated with increased cognitive dysfunction. Furthermore, this relationship remained even after the impact of psychological distress upon cognitive functioning was accounted for. TBI-related cognitive impairment primarily involved slowed reaction time, reduced attention and concentration, and difficulties in reasoning and problem-solving. These results complement previous findings of an inverse association between dose of TBI and self-perceptions of health and physical functioning in BMT survivors and indicate the importance of including quality of life measures in clinical trials of therapeutic innovations in the field of BMT.
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Affiliation(s)
- M A Andrykowski
- Department of Behavioral Science, University of Kentucky College of Medicine, Lexington 40536-0086
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Andrykowski MA, Henslee PJ, Barnett RL. Longitudinal assessment of psychosocial functioning of adult survivors of allogeneic bone marrow transplantation. Bone Marrow Transplant 1989; 4:505-9. [PMID: 2790328] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Existing research regarding the psychosocial functioning of adult survivors of allogeneic bone marrow transplantation (BMT) indicates that many patients experience difficulties in a variety of functional domains. A critical issue which has remained unexamined concerns the extent to which functioning improves, remains static, or perhaps even deteriorates with the passage of time post-BMT. To address this issue, the psychosocial functioning of 16 adult allogeneic BMT patients was assessed via a set of questionnaires on three occasions following their transplant. The initial assessment occurred a mean of 28 months post-BMT while the third assessment was a mean of 52 months post-BMT. Consistent with previous cross-sectional research, results indicated that many BMT survivors experience some long-term difficulties in physical, occupational, emotional, and cognitive functioning. Results indicated little change in functioning with the passage of time, suggesting that most patients might achieve a ceiling level of functioning within a couple of years post-BMT. At that time, further recovery of psychosocial functioning is likely to be minimal. Results are discussed with respect to their implications for both the encouragement of realistic expectations for post-BMT functioning as well as the development of post-BMT rehabilitation programs.
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Affiliation(s)
- M A Andrykowski
- Department of Behavioral Science, University of Kentucky College of Medicine, Lexington 40536-0086
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Amerson AB, Barnett RL, Butler JL, DeLuca PP. DRUG INFORMATION IN PHARMACY PRACTICE. J Clin Pharm Ther 1977. [DOI: 10.1111/j.1365-2710.1977.tb00092.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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