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Mason RP, Coulibaly M, Hansen G, Inman H, Myer PK, Yao KM. An examination of mercury levels in the coastal environment and fish of Cote d'Ivoire. Chemosphere 2022; 300:134609. [PMID: 35430197 DOI: 10.1016/j.chemosphere.2022.134609] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
Artisanal and small-scale gold mining (ASGM), energy production and other industrial inputs are a major source of anthropogenic mercury (Hg) to the aquatic environment globally, and these inputs have led to environmental contamination and human exposure. While studies have documented the effects of Hg inputs to rivers and marine waters of the West African region, estuarine waters of Cote d'Ivoire have been understudied, besides the waters surrounding Abidjan. To fill this gap, and to examine the potential for human exposure to methylmercury (MeHg), we measured the concentrations of total Hg, MeHg, and ancillary parameters in water (dissolved and particulate phases), sediment and fish to determine the extent of environmental impact and the potential for MeHg exposure for people consuming these fish. Levels of Hg and MeHg in sediment were elevated in the vicinity of the urban environment (up to 0.3 ng/g dry weight (dw) MeHg and 623 ng/g dw total Hg) and lowest in the more remote estuarine environments. Measurements of Hg in tuna and other larger pelagic coastal species indicated that levels were elevated but comparable to other North Atlantic regions. However, levels of Hg in fish, even smaller estuarine species, were such that the rural and urban populations are potentially being exposed to unsafe levels of MeHg, primarily as a result of the relatively high fish consumption in Cote d'Ivoire compared to other countries. Overall, both local point sources and the transport of Hg used in interior ASGM activities are the sources for Hg contamination to these coastal waters.
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Affiliation(s)
- R P Mason
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA.
| | - M Coulibaly
- Ecole Normale Superieure (ENS), Abidjan, Cote d'Ivoire
| | - G Hansen
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - H Inman
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - P K Myer
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - K M Yao
- Oceanographic Institute, Abidjan, Cote d'Ivoire
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Sherratt SCR, Libby P, Bhatt DL, Dawoud H, Malinski T, Mason RP. Omega-3 fatty acids differentially alter the expression of detoxification enzymes and nitric oxide bioavailability in endothelial cells during IL-6 exposure. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.3368] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Atherosclerotic plaques can elaborate reactive oxygen species (ROS) that reduce nitric oxide (NO) bioavailability. Cellular detoxification enzymes including various peroxiredoxin (PRDX) and superoxide dismutase (SOD) isoforms can inactivate ROS. The omega-3 fatty acid (n3-FA) eicosapentaenoic acid (EPA) reduced cardiovascular (CV) events in high-risk patients (REDUCE-IT), a benefit not observed with mixed n3-FAs containing docosahexaenoic acid (DHA).
Purpose
The purpose of this study was to compare the effects of EPA and DHA on NO bioavailability and expression of detoxification enzymes in the vascular endothelium in vitro.
Methods
Human umbilical vein endothelial cells (HUVECs) were pretreated with EPA or DHA at equimolar levels (10 μM) for 2 h, then challenged with IL-6 at 12 ng/ml for 24 h. Proteomic analysis was performed using LC/MS to measure relative protein expression. Only significant (p<0.05) changes between treatment groups >1-fold were analyzed. Cells were stimulated with calcium ionophore to measure NO and peroxynitrite (ONOO-) release using a porphyrinic nanosensor.
Results
EPA, but not DHA, augmented PRDX-2 and SOD1 expression in HUVECs relative to IL-6 alone (1.2-fold and 1.6-fold, respectively, p=0.03). EPA also significantly lowered other isoforms unlike DHA. Either EPA or DHA increased thioredoxin expression by 1.5-fold (p=0.001) and 1.3-fold (p=0.02), respectively and decreased SOD2 expression by 1.5-fold (p=8.75E-11) and 1.6-fold (p=6.03E-9), respectively. IL-6 alone only increased expression of 6 detoxification enzymes by at least 1.2-fold, relative to vehicle. Unlike DHA, EPA also increased the NO to ONOO- release ratio by 36% (p<0.05) relative to IL-6 alone, without changes in NO synthase (eNOS) expression.
Conclusions
n3-FAs differentially influenced NO bioavailability and expression of ROS detoxification proteins, including peroxiredoxin and SOD isoforms. The net benefits of EPA on eNOS function and ROS detoxification may contribute to reduced atherothrombotic risk compared to DHA.
Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Amarin Pharma Inc., Elucida Research
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Affiliation(s)
- S C R Sherratt
- Elucida Research LLC, Biophysics Department, Beverly, MA, United States of America
| | - P Libby
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
| | - D L Bhatt
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
| | - H Dawoud
- Ohio University, Department of Chemistry and Biochemistry, Athens, OH, United States of America
| | - T Malinski
- Ohio University, Department of Chemistry and Biochemistry, Athens, OH, United States of America
| | - R P Mason
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
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Sherratt SCR, Libby P, Dawoud H, Bhatt DL, Malinski T, Mason RP. Eicosapentaenoic acid inhibits lipopolysaccharide (LPS)-induced nitrite production and cytokine release from J774 macrophages. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.3351] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Eicosapentaenoic acid (EPA), an omega-3 (ω-3) fatty acid, reduced cardiovascular (CV) events in high-risk patients (REDUCE-IT) but the mechanism is not fully understood. Activated macrophages, characterized by cytokine release and increased inducible nitric oxide synthase (iNOS) activity, contribute to atherosclerosis. As both a substrate for and potential inhibitor of cyclooxygenase (COX), EPA may reduce iNOS activity.
Purpose
The purpose of this study was to evaluate the dose-dependent effects of EPA on nitrite and cytokine release from lipopolysaccharide (LPS)-activated macrophages.
Methods
Murine J774 macrophages were pretreated with vehicle or EPA at 10, 20 and 40 μM for 2 h, then challenged with LPS at 1.0 μg/ml. After 24 hr, iNOS activity was measured by nitrite production using the Griess assay. EPA was compared to the COX inhibitor diclofenac at 1.0 μg/ml. Levels of interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) in cell supernatant were measured by immunochemistry using colchicine as a positive control.
Results
Activated macrophages caused a >4-fold increase in nitrite production (p<0.001) that was reduced by EPA in a dose-dependent manner. EPA decreased nitrite levels by 40, 62 and 77% at 10, 20 and 40 μM, respectively (p<0.01). Diclofenac separately reduced nitrite levels by 40% (p<0.01). EPA also reduced expression of IL-1β and TNF-α by 40% and 31%, respectively (p<0.01), in a manner similar to equimolar colchicine (10 μM). The reductions in IL-1β and TNF-α with EPA were dose-dependent.
Conclusions
EPA reduced macrophage activation as evidenced by decreased nitrite production and cytokine release similar to other anti-inflammatory agents. These findings indicate a novel effect of EPA on mechanisms of inflammation associated with vascular disease.
Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Amarin Pharma Inc., Elucida Research
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Affiliation(s)
- S C R Sherratt
- Elucida Research LLC, Biophysics Department, Beverly, MA, United States of America
| | - P Libby
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
| | - H Dawoud
- Ohio University, Department of Chemistry and Biochemistry, Athens, OH, United States of America
| | - D L Bhatt
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
| | - T Malinski
- Ohio University, Department of Chemistry and Biochemistry, Athens, OH, United States of America
| | - R P Mason
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
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Sherratt SCR, Libby P, Bhatt DL, Dawoud H, Malinski T, Mason RP. Omega-3 fatty acids differentially reduced expression of neutrophil degranulation-associated proteins in endothelial cells during IL-6 exposure. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.3369] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Neutrophil degranulation contributes to atherogenesis and tissue injury. Mixed omega-3 fatty acid (n3-FA) formulations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have failed to reduce CV events compared to EPA only (REDUCE-IT), but the mechanisms are not understood.
Purpose
The purpose of this study was to compare the effects of EPA and DHA on expression of proteins linked to neutrophil degranulation in the vascular endothelium in vitro.
Methods
Human umbilical vein endothelial cells (HUVECs) were pretreated with EPA or DHA at equimolar levels (10 μM) for 2 h, then challenged with IL-6 at 12 ng/ml for 24 h. Proteomic analysis was performed using LC/MS to measure relative protein expression. Only significant (p<0.05) changes between treatment groups >1-fold were analyzed.
Results
In the Reactome “neutrophil degranulation” pathway, EPA and DHA downregulated 27 and 14 proteins, respectively, (p=9.97E-9 and 5.30E-4, respectively) relative to IL-6 alone. There were 12 protein changes common to both n3-FAs, including heme oxygenase-2 and ferritin light chain. EPA downregulated 15 proteins unlike DHA, including peroxiredoxin-6 and mitogen-activated protein kinase-1 (MAPK1). A combined 21 proteins downregulated by EPA and DHA versus IL-6 were upregulated by IL-6 alone relative to vehicle. EPA also increased expression of Rho-associated protein kinase-1 (ROCK-1), a protein downregulated by IL-6 alone and unaffected by DHA.
Conclusions
EPA and DHA differentially modulated expression of proteins linked to neutrophil degranulation. The distinct effects of EPA on protein expression may contribute to reduced inflammation in vascular injury compared to DHA.
Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Amarin Pharma Inc., Elucida Research
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Affiliation(s)
- S C R Sherratt
- Elucida Research LLC, Biophysics Department, Beverly, MA, United States of America
| | - P Libby
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
| | - D L Bhatt
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
| | - H Dawoud
- Ohio University, Department of Chemistry and Biochemistry, Athens, OH, United States of America
| | - T Malinski
- Ohio University, Department of Chemistry and Biochemistry, Athens, OH, United States of America
| | - R P Mason
- Brigham and Women'S Hospital, Harvard Medical School, Boston, United States of America
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5
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Buckman KL, Seelen EA, Mason RP, Balcom P, Taylor VF, Ward JE, Chen CY. Sediment organic carbon and temperature effects on methylmercury concentration: A mesocosm experiment. Sci Total Environ 2019; 666:1316-1326. [PMID: 30970496 PMCID: PMC6461384 DOI: 10.1016/j.scitotenv.2019.02.302] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/01/2019] [Accepted: 02/19/2019] [Indexed: 05/21/2023]
Abstract
The fate and mobility of mercury, and its bioaccumulation primarily as methylmercury (MeHg), in marine ecosystems are influenced by climate related environmental factors, including increased temperature and carbon loading. To investigate the interactions between sediment organic carbon and temperature MeHg bioaccumulation, mesocosm experiments were conducted examining relationships between sediment, water column and biota (sediment-dwelling amphipod and juvenile oyster) MeHg concentration. Experimental treatments consisted of a two by two design of high and low temperature (15 & 25 °C) and high and low sediment organic carbon (4-5% and 13% LOI, pre-experiment). Sediment organic carbon had significant individual effects on MeHg concentration in water and biota, with higher carbon associated with lower MeHg. Temperature individual effects were significant for sediment, water, and only amphipod MeHg concentration, with higher temperature treatments indicating higher MeHg concentration. There were significant temperature × carbon interactions observed for sediment, dissolved, and oyster MeHg concentration. Sediment carbon reduction had greater influence than temperature on increasing MeHg concentrations in both the water column and biota. MeHg concentrations in the bulk sediment were not correlated with MeHg in the water column or in the biota, indicating that even when sediments are the only source of MeHg, bulk sediment measurements do not provide a good proxy for bioaccumulation and that the concentration in bulk sediments is not the primary determinant of MeHg entry into the food web.
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Affiliation(s)
- K L Buckman
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States of America.
| | - E A Seelen
- Department of Marine Science, University of Connecticut, Groton, CT, United States of America
| | - R P Mason
- Department of Marine Science, University of Connecticut, Groton, CT, United States of America
| | - P Balcom
- Department of Marine Science, University of Connecticut, Groton, CT, United States of America; Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA, United States of America
| | - V F Taylor
- Department of Earth Science, Dartmouth College, Hanover, NH, United States of America
| | - J E Ward
- Department of Marine Science, University of Connecticut, Groton, CT, United States of America
| | - C Y Chen
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States of America
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Taylor VF, Buckman KL, Seelen EA, Mazrui NM, Balcom PH, Mason RP, Chen CY. Organic carbon content drives methylmercury levels in the water column and in estuarine food webs across latitudes in the Northeast United States. Environ Pollut 2019; 246:639-649. [PMID: 30605819 PMCID: PMC6363875 DOI: 10.1016/j.envpol.2018.12.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 05/21/2023]
Abstract
Estuaries are dynamic ecosystems which vary widely in loading of the contaminant methylmercury (MeHg), and in environmental factors which control MeHg exposure to the estuarine foodweb. Inputs of organic carbon and rates of primary production are important influences on MeHg loading and bioaccumulation, and are predicted to increase with changes in climate and land use pressures. To further understand these influences on MeHg levels in estuarine biota, we used a field study approach in sites across different temperature regions, and with varying organic carbon levels. In paired comparisons of sites with high vs. low organic carbon, fish had lower MeHg bioaccumulation factors (normalized to water concentrations) in high carbon sites, particularly subsites with large coastal wetlands and large variability in dissolved organic carbon levels in the water column. Across sites, MeHg level in the water column was strongly tied to dissolved organic carbon, and was the major driver of MeHg concentrations in fish and invertebrates. Higher primary productivity (chlorophyll-a) was associated with increased MeHg partitioning to suspended particulates, but not to the biota. These findings suggest that increased inputs of MeHg and loss of wetlands associated with climate change and anthropogenic land use pressure will increase MeHg concentrations in estuarine food webs.
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Affiliation(s)
- V F Taylor
- Department of Earth Science, Dartmouth College, Hanover, NH, USA.
| | - K L Buckman
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - E A Seelen
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - N M Mazrui
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - P H Balcom
- Harvard John A. Paulson School of Engineering & Applied Sciences, Cambridge, MA, USA
| | - R P Mason
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - C Y Chen
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
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7
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Outridge PM, Mason RP, Wang F, Guerrero S, Heimbürger-Boavida LE. Updated Global and Oceanic Mercury Budgets for the United Nations Global Mercury Assessment 2018. Environ Sci Technol 2018; 52:11466-11477. [PMID: 30226054 DOI: 10.1021/acs.est.8b01246] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In support of international efforts to reduce mercury (Hg) exposure in humans and wildlife, this paper reviews the literature concerning global Hg emissions, cycling and fate, and presents revised global and oceanic Hg budgets for the 2018 United Nations Global Mercury Assessment. We assessed two competing scenarios about the impacts of 16th - late 19th century New World silver (Ag) mining, which may be the largest human source of atmospheric Hg in history. Consideration of Ag ore geochemistry, historical documents on Hg use, and comparison of the scenarios against atmospheric Hg patterns in environmental archives, strongly support a "low mining emission" scenario. Building upon this scenario and other published work, the revised global budget estimates human activities including recycled legacy emissions have increased current atmospheric Hg concentrations by about 450% above natural levels (prevailing before 1450 AD). Current anthropogenic emissions to air are 2.5 ± 0.5 kt/y. The increase in atmospheric Hg concentrations has driven a ∼ 300% average increase in deposition, and a 230% increase in surface marine waters. Deeper marine waters show increases of only 12-25%. The overall increase in Hg in surface organic soils (∼15%) is small due to the large mass of natural Hg already present from rock weathering, but this figure varies regionally. Specific research recommendations are made to reduce uncertainties, particularly through improved understanding of fundamental processes of the Hg cycle, and continued improvements in emissions inventories from large natural and anthropogenic sources.
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Affiliation(s)
- P M Outridge
- Geological Survey of Canada , Natural Resources Canada , 601 Booth St. , Ottawa , Ontario K1A 0E8 , Canada
- Center for Earth Observation Science and Department of Environment and Geography , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
| | - R P Mason
- Department of Marine Sciences , University of Connecticut , 1080 Shennecossett Road , Groton , Connecticut 06340 , United States
| | - F Wang
- Center for Earth Observation Science and Department of Environment and Geography , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
| | - S Guerrero
- Universidad Metropolitana, Autopista Caracas Guarenas , Caracas 1073 , Venezuela
| | - L E Heimbürger-Boavida
- Aix Marseille Université , CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 , Marseille , France
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Gao W, Currin RJ, Lemasters JJ, Connor HD, Mason RP, Thurman RG. Reperfusion rather than storage injury predominates following long-term (48 h) cold storage of grafts in UW solution: studies with Carolina Rinse in rat liver. Transpl Int 2018. [DOI: 10.1111/tri.1992.5.s1.329] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Muñoz MD, Della Vedova MC, Bushel PR, Ganini da Silva D, Mason RP, Zhai Z, Gomez Mejiba SE, Ramirez DC. The nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide dampens lipopolysaccharide-induced transcriptomic changes in macrophages. Inflamm Res 2018; 67:515-530. [PMID: 29589052 DOI: 10.1007/s00011-018-1141-z] [Citation(s) in RCA: 4] [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: 01/17/2018] [Revised: 02/26/2018] [Accepted: 03/21/2018] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVE M1-like inflammatory phenotype of macrophages plays a critical role in tissue damage in chronic inflammatory diseases. Previously, we found that the nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) dampens lipopolysaccharide (LPS)-triggered inflammatory priming of RAW 264.7 cells. Herein, we tested whether DMPO by itself can induce changes in macrophage transcriptome, and that these effects may prevent LPS-induced activation of macrophages. MATERIALS AND METHODS To test our hypothesis, we performed a transcriptomic and bioinformatics analysis in RAW 264.7 cells incubated with or without LPS, in the presence or in the absence of DMPO. RESULTS Functional data analysis showed 79 differentially expressed genes (DEGs) when comparing DMPO vs Control. We used DAVID databases for identifying enriched gene ontology terms and Ingenuity Pathway Analysis for functional analysis. Our data showed that DMPO vs Control comparison of DEGs is related to downregulation immune-system processes among others. Functional analysis indicated that interferon-response factor 7 and toll-like receptor were related (predicted inhibitions) to the observed transcriptomic effects of DMPO. Functional data analyses of the DMPO + LPS vs LPS DEGs were consistent with DMPO-dampening LPS-induced inflammatory transcriptomic profile in RAW 264.7. These changes were confirmed using Nanostring technology. CONCLUSIONS Taking together our data, surprisingly, indicate that DMPO by itself affects gene expression related to regulation of immune system and that DMPO dampens LPS-triggered MyD88- and TRIF-dependent signaling pathways. Our research provides critical data for further studies on the possible use of DMPO as a structural platform for the design of novel mechanism-based anti-inflammatory drugs.
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Affiliation(s)
- M D Muñoz
- Laboratory of Experimental and Translational Medicine, IMIBIO-SL-School of Chemistry, Biochemistry and Pharmacy, National University of San Luis-CONICET, San Luis, 5700, San Luis, Argentina.,Laboratory of Experimental Therapeutics, School of Health Sciences-IMIBIO-SL, CONICET-National University of San Luis, San Luis, 5700, San Luis, Argentina
| | - M C Della Vedova
- Laboratory of Experimental and Translational Medicine, IMIBIO-SL-School of Chemistry, Biochemistry and Pharmacy, National University of San Luis-CONICET, San Luis, 5700, San Luis, Argentina.,Laboratory of Experimental Therapeutics, School of Health Sciences-IMIBIO-SL, CONICET-National University of San Luis, San Luis, 5700, San Luis, Argentina
| | - P R Bushel
- Biostatistics and Computational Biology Branch, NIEHS, NIH, USDHHS, RTP, Durham, 27709, NC, USA
| | - D Ganini da Silva
- Immunity, Inflammation and Disease Laboratory, NIEHS, NIH, USDHHS, RTP, Durham, 27709, NC, USA
| | - R P Mason
- Immunity, Inflammation and Disease Laboratory, NIEHS, NIH, USDHHS, RTP, Durham, 27709, NC, USA
| | - Z Zhai
- Department of Dermatology, University of Colorado Denver, Aurora, 80045, CO, USA
| | - S E Gomez Mejiba
- Laboratory of Experimental Therapeutics, School of Health Sciences-IMIBIO-SL, CONICET-National University of San Luis, San Luis, 5700, San Luis, Argentina.
| | - D C Ramirez
- Laboratory of Experimental and Translational Medicine, IMIBIO-SL-School of Chemistry, Biochemistry and Pharmacy, National University of San Luis-CONICET, San Luis, 5700, San Luis, Argentina.
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Towner RA, Smith N, Saunders D, Carrizales J, Lupu F, Silasi-Mansat R, Ehrenshaft M, Mason RP. In vivo targeted molecular magnetic resonance imaging of free radicals in diabetic cardiomyopathy within mice. Free Radic Res 2015; 49:1140-6. [PMID: 25968951 DOI: 10.3109/10715762.2015.1050587] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Free radicals contribute to the pathogenesis of diabetic cardiomyopathy. We present a method for in vivo observation of free radical events within murine diabetic cardiomyopathy. This study reports on in vivo imaging of protein/lipid radicals using molecular MRI (mMRI) and immuno-spin trapping (IST) in diabetic cardiac muscle. To detect free radicals in diabetic cardiomyopathy, streptozotocin (STZ)-exposed mice were given 5,5-dimethyl-pyrroline-N-oxide (DMPO) and administered an anti-DMPO probe (biotin-anti-DMPO antibody-albumin-Gd-DTPA). For controls, non-diabetic mice were given DMPO (non-disease control), and administered an anti-DMPO probe; or diabetic mice were given DMPO but administered a non-specific IgG contrast agent instead of the anti-DMPO probe. DMPO administration started at 7 weeks following STZ treatment for 5 days, and the anti-DMPO probe was administered at 8 weeks for MRI detection. MRI was used to detect a significant increase (p < 0.001) in MRI signal intensity (SI) from anti-DMPO nitrone adducts in diabetic murine left-ventricular (LV) cardiac tissue, compared to controls. Regional increases in MR SI in the LV were found in the apical and upper-left areas (p < 0.01 for both), compared to controls. The biotin moiety of the anti-DMPO probe was targeted with fluorescently-labeled streptavidin to locate the anti-DMPO probe in excised cardiac tissues, which indicated elevated fluorescence only in cardiac muscle of mice administered the anti-DMPO probe. Oxidized lipids and proteins were also found to be significantly elevated (p < 0.05 for both) in diabetic cardiac muscle compared to controls. It can be concluded that diabetic mice have more heterogeneously distributed radicals in cardiac tissue than non-diabetic mice.
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Affiliation(s)
- R A Towner
- Advanced Magnetic Resonance Center, Oklahoma Medical Research Foundation , Oklahoma City, OK , USA
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11
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Cao J, Lopez R, Thacker JM, Moon JY, Jiang C, Morris SNS, Bauer JH, Tao P, Mason RP, Lippert AR. Chemiluminescent Probes for Imaging H 2S in Living Animals. Chem Sci 2015; 6:1979-1985. [PMID: 25709805 PMCID: PMC4335805 DOI: 10.1039/c4sc03516j] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/31/2014] [Indexed: 12/18/2022] Open
Abstract
Hydrogen sulphide (H2S) is an endogenous mediator of human health and disease, but precise measurement in living cells and animals remains a considerable challenge. We report the total chemical synthesis and characterization of three 1,2-dioxetane chemiluminescent reaction-based H2S probes, CHS-1, CHS-2, and CHS-3. Upon treatment with H2S at physiological pH, these probes display instantaneous light emission that is sustained for over an hour with high selectivity against other reactive sulphur, oxygen, and nitrogen species. Analysis of the phenol/phenolate equilibrium and atomic charges has provided a generally applicable predictive model to design improved chemiluminescent probes. The utility of these chemiluminescent reagents was demonstrated by applying CHS-3 to detect cellularly generated H2S using a multi-well plate reader and to image H2S in living mice using CCD camera technology.
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Affiliation(s)
- J. Cao
- Department of Chemistry , Southern Methodist University , Dallas , TX 75275-0314 , USA .
- Center for Drug Discovery , Design, and Delivery (CD4) , Southern Methodist University , Dallas , TX 75275-0314 , USA
| | - R. Lopez
- Laboratory of Prognostic Radiology , Pre-clinical Imaging Section , Department of Radiology , UT Southwestern Medical Center , Dallas , TX 75390-9058 , USA
| | - J. M. Thacker
- Department of Chemistry , Southern Methodist University , Dallas , TX 75275-0314 , USA .
| | - J. Y. Moon
- Department of Chemistry , Southern Methodist University , Dallas , TX 75275-0314 , USA .
| | - C. Jiang
- Hockaday School , Dallas , TX 75229 , USA
| | - S. N. S. Morris
- Department of Biological Sciences , Southern Methodist University , Dallas , TX 75275-0314 , USA
| | - J. H. Bauer
- Center for Drug Discovery , Design, and Delivery (CD4) , Southern Methodist University , Dallas , TX 75275-0314 , USA
- Department of Biological Sciences , Southern Methodist University , Dallas , TX 75275-0314 , USA
| | - P. Tao
- Department of Chemistry , Southern Methodist University , Dallas , TX 75275-0314 , USA .
- Center for Drug Discovery , Design, and Delivery (CD4) , Southern Methodist University , Dallas , TX 75275-0314 , USA
| | - R. P. Mason
- Laboratory of Prognostic Radiology , Pre-clinical Imaging Section , Department of Radiology , UT Southwestern Medical Center , Dallas , TX 75390-9058 , USA
| | - A. R. Lippert
- Department of Chemistry , Southern Methodist University , Dallas , TX 75275-0314 , USA .
- Center for Drug Discovery , Design, and Delivery (CD4) , Southern Methodist University , Dallas , TX 75275-0314 , USA
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Mason RP, Corbalan JJ, Jacob RF, Dawoud H, Malinski T. Atorvastatin enhanced nitric oxide release and reduced blood pressure, nitroxidative stress and rantes levels in hypertensive rats with diabetes. J Physiol Pharmacol 2015; 66:65-72. [PMID: 25716966] [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] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/12/2014] [Indexed: 06/04/2023]
Abstract
Clinical trials have shown that atorvastatin benefits patients with diabetes even with normal baseline LDL levels. We hypothesized that atorvastatin improves endothelial cell (EC) function and reduces inflammation in hypertensive rats with diabetes. Non-diabetic and streptozotocin-induced type 2 diabetic male spontaneously hypertensive rats (SHR) were treated with atorvastatin at 20 mg/kg/day. After five weeks, nitric oxide (NO) and peroxynitrite (ONOO(-)) were measured in aortic and glomerular endothelial cells. A tandem of nanosensors was used to simultaneously measure NO and ONOO(-) concentration and their ratio [NO]/[ONOO(-)] was monitored with a time resolution better than 10 μs and detection limit 1 nM. [NO]/[ONOO(-)] was applied as a marker of endothelial NO synthase (eNOS) uncoupling, endothelial dysfunction and nitroxidative stress. Glucose, cholesterol, blood pressure (BP), and the cytokine RANTES were also measured. Diabetic SHR rats had elevated glucose (355 ± 38 mg/dL), mean BP (172 ± 15 mmHg), and plasma RANTES (38.4 ± 2.7 ng/mL), low endothelial NO bioavailability and high ONOO(-). Maximal NO release measured 267 ± 29 nM in aortic endothelium of SHR rats and 214 ± 20 nM for diabetic SHR rats; [NO]/[ONOO(-)] was 0.88 ± 12 and 0.61 ± 0.08, respectively. [NO]/[ONOO(-)] ratios below one indicate a high uncoupling of eNOS, endothelial dysfunction and high nitroxidative stress. Atorvastatin treatment partially restored endothelial function by increasing NO level by 98%, reducing ONOO(-) by 40% and favorably elevating [NO]/[ONOO(-)] to 1.1 ± 0.2 for diabetic SHR rats and 1.6 ± 0.3 for SHR rats. The effects of atorvastatin were similar in glomerular endothelial cells and were partially reproduced by modulators of eNOS or NADPH oxidase. Atorvastatin had no significant effect on fasting glucose or total cholesterol levels but reduced mean BP by 21% and 11% in diabetic and non-diabetic animals, respectively. Atorvastatin also reduced RANTES levels by 50%. Atorvastatin favorably increased the [NO]/[ONOO(-)] balance, enhanced endothelial cytoprotective NO, decreased cytotoxic ONOO(-) and reduced BP, inflammation and RANTES levels in diabetic, hypertensive rats without altering cholesterol levels. These findings provide insights into mechanisms of restoration of endothelial function and vascular protection by atorvastatin in diabetes and hypertension.
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Affiliation(s)
- R P Mason
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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Shvedova AA, Kisin ER, Murray AR, Mouithys-Mickalad A, Stadler K, Mason RP, Kadiiska M. ESR evidence for in vivo formation of free radicals in tissue of mice exposed to single-walled carbon nanotubes. Free Radic Biol Med 2014; 73:154-65. [PMID: 24863695 DOI: 10.1016/j.freeradbiomed.2014.05.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 04/28/2014] [Accepted: 05/16/2014] [Indexed: 11/28/2022]
Abstract
Nanomaterials are being utilized in an increasing variety of manufactured goods. Because of their unique physicochemical, electrical, mechanical, and thermal properties, single-walled carbon nanotubes (SWCNTs) have found numerous applications in the electronics, aerospace, chemical, polymer, and pharmaceutical industries. Previously, we have reported that pharyngeal exposure of C57BL/6 mice to SWCNTs caused dose-dependent formation of granulomatous bronchial interstitial pneumonia, fibrosis, oxidative stress, acute inflammatory/cytokine responses, and a decrease in pulmonary function. In the current study, we used electron spin resonance (ESR) to directly assess whether exposure to respirable SWCNTs caused formation of free radicals in the lungs and in two distant organs, the heart and liver. Here we report that exposure to partially purified SWCNTs (HiPco technique, Carbon Nanotechnologies, Inc., Houston, TX, USA) resulted in the augmentation of oxidative stress as evidenced by ESR detection of α-(4-pyridyl-1-oxide)-N-tert-butylnitrone spin-trapped carbon-centered lipid-derived radicals recorded shortly after the treatment. This was accompanied by a significant depletion of antioxidants and elevated biomarkers of inflammation presented by recruitment of inflammatory cells and an increase in proinflammatory cytokines in the lungs, as well as development of multifocal granulomatous pneumonia, interstitial fibrosis, and suppressed pulmonary function. Moreover, pulmonary exposure to SWCNTs also caused the formation of carbon-centered lipid-derived radicals in the heart and liver at later time points (day 7 postexposure). Additionally, SWCNTs induced a significant accumulation of oxidatively modified proteins, increase in lipid peroxidation products, depletion of antioxidants, and inflammatory response in both the heart and the liver. Furthermore, the iron chelator deferoxamine noticeably reduced lung inflammation and oxidative stress, indicating an important role for metal-catalyzed species in lung injury caused by SWCNTs. Overall, we provide direct evidence that lipid-derived free radicals are a critical contributor to tissue damage induced by SWCNTs not only in the lungs, but also in distant organs.
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Affiliation(s)
- A A Shvedova
- Pathology and Physiology Research Branch, HELD, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA; Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA.
| | - E R Kisin
- Pathology and Physiology Research Branch, HELD, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - A R Murray
- Pathology and Physiology Research Branch, HELD, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA; Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA
| | | | - K Stadler
- National Institute of Environmental Health Science, Research Triangle Park, NC 27709, USA
| | - R P Mason
- National Institute of Environmental Health Science, Research Triangle Park, NC 27709, USA
| | - M Kadiiska
- National Institute of Environmental Health Science, Research Triangle Park, NC 27709, USA
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Mason RP. Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil. Cardiovasc Ther Prev 2012. [DOI: 10.15829/1728-8800-2012-3-102-112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin– angiotensin–aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.
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Mason RP. TU-E-214-04: NMR Assessment of Tumor Hypoxia and Oxygen Dynamics. Med Phys 2011. [DOI: 10.1118/1.3613202] [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: 11/07/2022] Open
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Kucejova B, Sunny NE, Nguyen AD, Hallac R, Fu X, Peña-Llopis S, Mason RP, Deberardinis RJ, Xie XJ, Debose-Boyd R, Kodibagkar VD, Burgess SC, Brugarolas J. Uncoupling hypoxia signaling from oxygen sensing in the liver results in hypoketotic hypoglycemic death. Oncogene 2011; 30:2147-60. [PMID: 21217781 PMCID: PMC3135264 DOI: 10.1038/onc.2010.587] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
As the ultimate electron acceptor in oxidative phosphorylation, oxygen plays a critical role in metabolism. When oxygen levels drop, heterodimeric hypoxia-inducible factor (Hif) transcription factors become active and facilitate adaptation to hypoxia. Hif regulation by oxygen requires the protein von Hippel-Lindau (pVhl) and pVhl disruption results in constitutive Hif activation. The liver is a critical organ for metabolic homeostasis, and Vhl inactivation in hepatocytes results in a Hif-dependent shortening in life span. While albumin-Cre;VhlF/F mice develop hepatic steatosis and impaired fatty acid oxidation, the variable penetrance and unpredictable life expectancy has made the cause of death elusive. Using a system in which Vhl is acutely disrupted and a combination of ex vivo liver perfusion studies and in vivo oxygen measurements, we demonstrate that Vhl is essential for mitochondrial respiration in vivo. Adenovirus-Cre mediated acute Vhl disruption in the liver caused death within days. Deprived of pVhl, livers accumulated tryglicerides and circulating ketone and glucose levels dropped. The phenotype was reminiscent of inborn defects in fatty acid oxidation and of fasted PPARα-deficient mice and while death was unaffected by pharmacologic PPARα activation, it was delayed by glucose administration. Ex vivo liver perfusion analyses and acylcarnitine profiles showed mitochondrial impairment and a profound inhibition of liver ketone and glucose production. By contrast, other mitochondrial functions, such as ureagenesis, were unaffected. Oxygen consumption studies revealed a marked suppression of mitochondrial respiration, which, as determined by magnetic resonance oximetry in live mice, was accompanied by a corresponding increase in liver pO2. Importantly, simultaneous inactivation of Hif-1β suppressed liver steatosis and rescued the mice from death. These data demonstrate that constitutive Hif activation in mice is sufficient to suppress mitochondrial respiration in vivo and that no other pathway exists in the liver that can allow oxygen utilization when Hif is active precluding thereby metabolic collapse.
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Affiliation(s)
- B Kucejova
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Mason RP, Zhao D, Pacheco-Torres J, Cui W, Kodibagkar VD, Gulaka PK, Hao G, Thorpe P, Hahn EW, Peschke P. Multimodality imaging of hypoxia in preclinical settings. Q J Nucl Med Mol Imaging 2010; 54:259-280. [PMID: 20639813 PMCID: PMC3044928] [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] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Hypoxia has long been recognized to influence solid tumor response to therapy. Increasingly, hypoxia has also been implicated in tumor aggressiveness, including growth, development and metastatic potential. Thus, there is a fundamental, as well as a clinical interest, in assessing in situ tumor hypoxia. This review will examine diverse approaches focusing on the preclinical setting, particularly, in rodents. The strategies are inevitably a compromise in terms of sensitivity, precision, temporal and spatial resolution, as well as cost, feasibility, ease and robustness of implementation. We will review capabilities of multiple modalities and examine what makes them particularly suitable for investigating specific aspects of tumor pathophysiology. Current approaches range from nuclear imaging to magnetic resonance and optical, with varying degrees of invasiveness and ability to examine spatial heterogeneity, as well as dynamic response to interventions. Ideally, measurements would be non-invasive, exploiting endogenous reporters to reveal quantitatively local oxygen tension dynamics. A primary focus of this review is magnetic resonance imaging (MRI) based techniques, such as ¹⁹F MRI oximetry, which reveals not only hypoxia in vivo, but more significantly, spatial distribution of pO₂ quantitatively, with a precision relevant to radiobiology. It should be noted that preclinical methods may have very different criteria for acceptance, as compared with potential investigations for prognostic radiology or predictive biomarkers suitable for use in patients.
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Affiliation(s)
- R P Mason
- Department of Radiology, U.T. Southwestern Medical Center, Dallas, TX 75390-9058, USA.
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Jennewein M, Qaim SM, Kulkarni PV, Mason RP, Hermanne A, Rösch F. A no-carrier-added72Se/72As radionuclide generator based on solid phase extraction. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2005.93.9-10.579] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Summary72As-labelled radiopharmaceuticals could be a valuable resource for Positron Emission Tomography (PET). In particular, the long half-life of72As (T1/2= 26 h) facilitates the observation of long-term physiological or metabolic processes, such as the enrichment and distribution of antibodies in tumor tissue. This work describes the primary radiochemical separation of no-carrier-added (nca)72Se from cyclotron irradiated germanium targets and the development of a polystyrene type solid-phase extraction based72Se/72As radionuclide generator, avoiding the addition of any selenium carrier. The irradiated germanium target is dissolved in HFconcand selenium is reduced with hydrazine dihydrochloride. The nca72Se(0)is adsorbed on a solid-phase extraction cartridge, representing the generator column. The72As is eluted using various aqueous solvents with 40–60% yield and < 0.1%72Se content. To be able to study the radiopharmaceutical arsenic chemistry, subsequent chemical modification of the nca72As eluates to nca [72As]AsI3provides a versatile radioarsenic labelling synthon.
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Liu B, Schaider LA, Mason RP, Bank MS, Rabalais NN, Swarzenski PW, Shine JP, Hollweg T, Senn DB. Disturbance impacts on mercury dynamics in northern Gulf of Mexico sediments. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jg000752] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- B. Liu
- Harvard School of Public Health; Harvard University; Boston Massachusetts USA
| | - L. A. Schaider
- Harvard School of Public Health; Harvard University; Boston Massachusetts USA
| | - R. P. Mason
- Department of Marine Sciences; University of Connecticut; Groton Connecticut USA
| | - M. S. Bank
- Harvard School of Public Health; Harvard University; Boston Massachusetts USA
| | - N. N. Rabalais
- Louisiana Universities Marine Consortium; Chauvin Louisiana USA
| | | | - J. P. Shine
- Harvard School of Public Health; Harvard University; Boston Massachusetts USA
| | - T. Hollweg
- Department of Marine Sciences; University of Connecticut; Groton Connecticut USA
| | - D. B. Senn
- Harvard School of Public Health; Harvard University; Boston Massachusetts USA
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Kading TJ, Mason RP, Leaner JJ. Mercury contamination history of an estuarine floodplain reconstructed from a 210Pb-dated sediment core (Berg River, South Africa). Mar Pollut Bull 2009; 59:116-122. [PMID: 19321182 DOI: 10.1016/j.marpolbul.2009.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 01/05/2009] [Accepted: 02/18/2009] [Indexed: 05/27/2023]
Abstract
Mercury deposition histories have been scarcely documented in the southern hemisphere. A sediment core was collected from the ecologically important estuarine floodplain of the Berg River (South Africa). We establish the concentration of Hg in this (210)Pb-dated sediment core at <50 ng g(-1) Hg(T) throughout the core, but with 1.3 ng g(-1) methylmercury in surface sediments. The (210)Pb dating of the core provides a first record of mercury deposition to the site and reveals the onset of enhanced mercury deposition in 1970. The ratio of methylmercury to total mercury is relatively high in these sediments when compared to other wetlands.
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Affiliation(s)
- T J Kading
- Wesleyan University, Department of Earth and Environmental Studies, 265 Church Street Middletown, CT 06457, USA.
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Brimfield AA, Mancebo AM, Mason RP, Jiang JJ, Siraki AG, Novak MJ. Free radical production from the interaction of 2-chloroethyl vesicants (mustard gas) with pyridine nucleotide-driven flavoprotein electron transport systems. Toxicol Appl Pharmacol 2008; 234:128-34. [PMID: 18977373 DOI: 10.1016/j.taap.2008.10.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [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] [Received: 08/15/2008] [Revised: 09/30/2008] [Accepted: 10/02/2008] [Indexed: 11/17/2022]
Abstract
The biochemical sequelae to chloroethyl mustard exposure correspond very well to toxic processes initiated by free radicals. Additionally, mustard solutions contain spontaneously formed cyclic onium ions which produce carbon free radicals when reduced electrochemically. Therefore, we hypothesized that the onium ions of sulfur or nitrogen mustards might produce carbon free radicals upon being reduced enzymatically, and that these radicals might constitute a metabolic activation. We set out to document radical production using an in vitro metabolic system and electron paramagnetic resonance (EPR). Our system consisted of NADPH, one of several pyridine nucleotide-driven flavoprotein reductases, cytochrome c as a terminal electron acceptor, various sulfur or nitrogen mustards and the spin trap alpha-[4-pyridyl-1-oxide]-N-tert-butylnitrone in buffer. Reactions were started by adding the reductase to the other materials, vortexing and immediately transferring the mixture to a 10 mm EPR flat cell. Repeated scans on a Bruker ESP 300E EPR spectrometer produced a triplet of doublets with hyperfine splitting constants of a(N)=15.483 G and a(H)=2.512 G. The outcome supported our hypothesis that carbon-centered free radicals are produced when mustard-related onium ions are enzymatically reduced. The EPR results varied little with the chloroethyl compound used or with porcine or human cytochrome P450 reductase, the reductase domain of rat brain neuronal nitric oxide synthase or rat liver thioredoxin reductase. Our results offer new insight into the basis for mustard-induced vesication and the outcome of exposure to different mustards. The free radical model provides an explanation for similarities in the lesions arising from mustard exposure and energy-based lesions such as those from heat, ultraviolet and nuclear radiation as well as damage across tissue types such as skin, eyes or airway epithelium.
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Affiliation(s)
- A A Brimfield
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA.
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Abstract
The Hg-methylating ability of dissimilatory iron-reducing bacteria in the genera Geobacter, Desulfuromonas, and Shewanella was examined. All of the Geobacter and Desulfuromonas strains tested methylated mercury while reducing Fe(III), nitrate, or fumarate. In contrast, none of the Shewanella strains produced methylmercury at higher levels than abiotic controls under similar culture conditions. Geobacter and Desulfuromonas are closely related to known Hg-methylating sulfate-reducing bacteria within the Deltaproteobacteria.
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Affiliation(s)
- E J Kerin
- University of Maryland, Chesapeake Biological Laboratory, Solomons, MD, USA
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Abstract
Blood oxygen level-dependent (BOLD) contrast magnetic resonance imaging (MRI) has been applied to investigate kidney oxygenation in human patients. These investigations reflect the progress of radiology from a primarily anatomic discipline to one that provides insight into tissue physiology. In particular, magnetic resonance imaging (MRI) is non-invasive, uses no ionizing radiation, and provides insight into disease development and tissue physiology.
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Affiliation(s)
- R P Mason
- Laboratory of Prognostic Radiology, Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9058, USA.
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Jennewein M, Qaim SM, Hermanne A, Jahn M, Tsyganov E, Slavine N, Seliounine S, Antich PA, Kulkarni PV, Thorpe PE, Mason RP, Rösch F. A new method for radiochemical separation of arsenic from irradiated germanium oxide. Appl Radiat Isot 2005; 63:343-51. [PMID: 15955705 DOI: 10.1016/j.apradiso.2005.04.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2005] [Revised: 04/04/2005] [Accepted: 04/13/2005] [Indexed: 11/30/2022]
Abstract
Radioarsenic labelled radiopharmaceuticals could be a valuable asset to Positron Emission Tomography (PET). In particular, the long half-lives of (72)As (T(1/2)=26 h) and (74)As (T(1/2)=17.8 d) allow to investigate slow physiological or metabolical processes, like the enrichment and distribution of antibodies in tumor tissue. This work describes the direct production of no-carrier-added (nca) arsenic isotopes *As, with *=71, 72, 73, 74 or 77, the reaction to [*As]AsI(3) and its radiochemical separation from the irradiated solid germanium oxide via polystyrene-based solid-phase extraction. The germanium oxide target, irradiated at a cyclotron or a nuclear reactor, is dissolved in concentrated HF and Ge is separated almost quantitatively (99.97%) as [GeF(6)](2-). [*As]AsI(3) is formed by addition of potassium iodide. The radiochemical separation yield for arsenic is >90%. [*As]AsI(3) is a versatile radioarsenic labelling synthon.
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Affiliation(s)
- M Jennewein
- Institute of Nuclear Chemistry, Johannes Gutenberg University of Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz, Germany
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Kadiiska MB, Gladen BC, Baird DD, Graham LB, Parker CE, Ames BN, Basu S, Fitzgerald GA, Lawson JA, Marnett LJ, Morrow JD, Murray DM, Plastaras J, Roberts LJ, Rokach J, Shigenaga MK, Sun J, Walter PB, Tomer KB, Barrett JC, Mason RP. Biomarkers of oxidative stress study III. Effects of the nonsteroidal anti-inflammatory agents indomethacin and meclofenamic acid on measurements of oxidative products of lipids in CCl4 poisoning. Free Radic Biol Med 2005; 38:711-8. [PMID: 15721981 DOI: 10.1016/j.freeradbiomed.2004.10.024] [Citation(s) in RCA: 310] [Impact Index Per Article: 16.3] [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] [Received: 01/30/2004] [Accepted: 10/20/2004] [Indexed: 11/18/2022]
Abstract
Plasma and urinary levels of malondialdehyde-like products (MDA) and isoprostanes were identified as markers of in vivo lipid peroxidation in an animal model of CCl4 poisoning. We sought to determine the extent to which the formation of these oxidation products is influenced by inhibition of the cyclooxygenase enzymes which catalytically generate proinflammatory lipid peroxidation products known as prostaglandins and thromboxane. In the present studies, after induction of oxidant stress in rats with CCl4, lipid peroxidation products measured in plasma and urine demonstrate that isoprostanes and MDA can be partially inhibited by cyclooxygenase inhibitors, albeit to different extents. The lowering of isoprostane and MDA formation, however, may not to due primarily to the diminution of catalytic generation of isoprostanes or MDA by the cyclooxygenases but, rather, may be the result of the suppression of nonenzymatic lipid peroxidation. This is suggested since 8,12-iso-iPF2alpha-VI is also reduced by indomethacin, yet, unlike other isoprostanes and MDA, it is not generated catalytically by the cyclooxygenase. Thus, although the two cyclooxygenase inhibitors we tested have statistically significant effects on the measurements of both isoprostanes and MDA in this study, the results provide evidence that these lipid-degradation products primarily constitute markers of oxidative stress.
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Affiliation(s)
- M B Kadiiska
- National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA.
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Kadiiska MB, Gladen BC, Baird DD, Germolec D, Graham LB, Parker CE, Nyska A, Wachsman JT, Ames BN, Basu S, Brot N, Fitzgerald GA, Floyd RA, George M, Heinecke JW, Hatch GE, Hensley K, Lawson JA, Marnett LJ, Morrow JD, Murray DM, Plastaras J, Roberts LJ, Rokach J, Shigenaga MK, Sohal RS, Sun J, Tice RR, Van Thiel DH, Wellner D, Walter PB, Tomer KB, Mason RP, Barrett JC. Biomarkers of oxidative stress study II: are oxidation products of lipids, proteins, and DNA markers of CCl4 poisoning? Free Radic Biol Med 2005; 38:698-710. [PMID: 15721980 DOI: 10.1016/j.freeradbiomed.2004.09.017] [Citation(s) in RCA: 501] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Accepted: 09/20/2004] [Indexed: 12/20/2022]
Abstract
Oxidation products of lipids, proteins, and DNA in the blood, plasma, and urine of rats were measured as part of a comprehensive, multilaboratory validation study searching for noninvasive biomarkers of oxidative stress. This article is the second report of the nationwide Biomarkers of Oxidative Stress Study using acute CCl4 poisoning as a rodent model for oxidative stress. The time-dependent (2, 7, and 16 h) and dose-dependent (120 and 1200 mg/kg i.p.) effects of CCl4 on concentrations of lipid hydroperoxides, TBARS, malondialdehyde (MDA), isoprostanes, protein carbonyls, methionine sulfoxidation, tyrosine products, 8-hydroxy-2'-deoxyguanosine (8-OHdG), leukocyte DNA-MDA adducts, and DNA-strand breaks were investigated to determine whether the oxidative effects of CCl4 would result in increased generation of these oxidation products. Plasma concentrations of MDA and isoprostanes (both measured by GC-MS) and urinary concentrations of isoprostanes (measured with an immunoassay or LC/MS/MS) were increased in both low-dose and high-dose CCl4-treated rats at more than one time point. The other urinary markers (MDA and 8-OHdG) showed significant elevations with treatment under three of the four conditions tested. It is concluded that measurements of MDA and isoprostanes in plasma and urine as well as 8-OHdG in urine are potential candidates for general biomarkers of oxidative stress. All other products were not changed by CCl4 or showed fewer significant effects.
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Affiliation(s)
- M B Kadiiska
- Department of Health and Human Services, National Institute of Environmental Health Sciences, National Institutes of Health, P.O. Box 12233, MD F0-02, Research Triangle Park, NC 27709, USA.
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Kadiiska MB, Ghio AJ, Mason RP. ESR investigation of the oxidative damage in lungs caused by asbestos and air pollution particles. Spectrochim Acta A Mol Biomol Spectrosc 2004; 60:1371-1377. [PMID: 15134737 DOI: 10.1016/j.saa.2003.10.035] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Accepted: 10/19/2003] [Indexed: 05/24/2023]
Abstract
Exposure to asbestos and air pollution particles can be associated with increased human morbidity and mortality. However, the molecular mechanism of lung injuries remains unknown. It has been postulated that the in vivo toxicity results from the catalysis of free radical generation. Using electron spin resonance (ESR) in conjunction with the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) we previously investigated in vivo free radical production by rats treated with intratracheal instillation of asbestos (crocidolite fibers) and an emission source air pollution particle (oil fly ash). In this report we compare the effect of two different exposures on the type of free radicals they induce in in vivo animal model. Twenty-four hours after the exposure, ESR spectroscopy of the chloroform extract from lungs of animals exposed to either asbestos or oil fly ash gave a spectrum consistent with a carbon-centered radical adduct (aN = 15.01 G and aH = 2.46 G). To test whether free radical formation occurred in vivo and not in vitro, a number of control experiments were performed. Combinations (both individually and together) of asbestos or oil fly ash and 4-POBN were added to lung homogenate of unexposed rats prior to chloroform extraction. No detectable ESR signal resulted. To exclude the possibility of ex vivo free radical generation, asbestos or oil fly ash was added to lung homogenate of an animal treated with 4-POBN. Also, 4-POBN was added to lung homogenate from rats instilled with asbestos or oil fly ash. Neither system produced radical adducts, indicating that the ESR signal detected in the lung extracts of the treated animals must be produced in vivo and not ex vivo or in vitro. In conclusion, ESR analysis of lung tissue demonstrated that both exposures produce lipid-derived radical metabolites despite their different composition and structure. Analogously, both exposures provide evidence of in vivo enhanced lipid peroxidation. Furthermore, it is concluded that without the presence of a spin-trapping agent, no free radical metabolites could be detected directly by ESR in either exposure.
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Affiliation(s)
- M B Kadiiska
- National Institute of Environmental Health Sciences, National Institutes of Health, MD F0-02, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
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Abstract
Calcium channel blockers (CCBs) were developed as vasodilators, and their use in cardiovascular disease treatment remains largely based on that mechanism of action. More recently, with the evolution of second- and third-generation CCBs, pleiotropic effects have been observed, and at least some of CCBs’ benefit is attributable to these mechanisms. Understanding these effects has contributed greatly to elucidating disease mechanisms and the rationale for CCB use. Furthermore, this knowledge might clarify why drugs are useful in some disease states, such as atherosclerosis, but not in others, such as heart failure. Although numerous drugs used in the treatment of vascular disease, including statins and angiotensin-converting–enzyme inhibitors, have well-described pleiotropic effects universally accepted to contribute to their benefit, little attention has been paid to CCBs’ potentially similar effects. Accumulating evidence that at least 1 CCB, amlodipine, has pharmacologic actions distinct from L-type calcium channel blockade prompted us to investigate the pleiotropic actions of amlodipine and CCBs in general. There are several areas of research; foci here are (1) the physicochemical properties of amlodipine and its interaction with cholesterol and oxidants; (2) the mechanism by which amlodipine regulates NO production and implications; and (3) amlodipine’s role in controlling smooth muscle cell proliferation and matrix formation.
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Affiliation(s)
- R P Mason
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass, USA
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Bellemann ME, Brückner J, Peschke P, Brix G, Mason RP. [Quantification and visualization of oxygen partial pressure in vivo by 19F NMR imaging of perfluorocarbons]. BIOMED ENG-BIOMED TE 2003; 47 Suppl 1 Pt 1:451-4. [PMID: 12451890 DOI: 10.1515/bmte.2002.47.s1a.451] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [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: 11/15/2022]
Abstract
Due to the high solubility of molecular oxygen in perfluorocabons (PFC), this class of fluorinated compounds has gained wide-spread interest for its biomedical application as temporary blood substitutes and as radiosensitizers. Since the observation that the NMR spin-lattice relaxation times (T1) of some 19F PFC resonances are sensitive to oxygen tension (pO2), this paramagnetic effect has been used to non-invasively probe pO2 in vivo. In this study, combined 19F/1H NMR image data of Copenhagen rats after PFC application were evaluated with the software package MATLAB. The analysis of the 19F NMR data resulted in image matrices with calculated T1 values in each pixel. By using a calibration curve, the corresponding pO2 values were computed. Color overlays of pO2 contour lines on T1-weighted 1H images show a good anatomical-functional correspondence.
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Affiliation(s)
- M E Bellemann
- Department of Biomedical Engineering, University of Applied Sciences, Jena, Germany.
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Shvedova AA, Kisin ER, Murray AR, Kommineni C, Castranova V, Mason RP, Kadiiska MB, Gunther MR. Antioxidant balance and free radical generation in vitamin e-deficient mice after dermal exposure to cumene hydroperoxide. Chem Res Toxicol 2002; 15:1451-9. [PMID: 12437336 DOI: 10.1021/tx0200313] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.3] [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: 11/29/2022]
Abstract
Organic peroxides are widely used in the chemical industry as initiators of oxidation for the production of polymers and fiber-reinforced plastics, in the manufacture of polyester resin coatings, and pharmaceuticals. Free radical production is considered to be one of the key factors contributing to skin tumor promotion by organic peroxides. In vitro experiments have demonstrated metal-catalyzed formation of alkoxyl, alkyl, and aryl radicals in keratinocytes incubated with cumene hydroperoxide. The present study investigated in vivo free radical generation in lipid extracts of mouse skin exposed to cumene hydroperoxide. The electron spin resonance (ESR) spin-trapping technique was used to detect the formation of alpha-phenyl-N-tert-butylnitrone (PBN) radical adducts, following intradermal injection of 180 mg/kg PBN. It was found that 30 min after topical exposure, cumene hydroperoxide (12 mmol/kg) induced free radical generation in the skin of female Balb/c mice kept for 10 weeks on vitamin E-deficient diets. In contrast, hardly discernible radical adducts were detected when cumene hydroperoxide was applied to the skin of mice fed a vitamin E-sufficient diet. Importantly, total antioxidant reserve and levels of GSH, ascorbate, and vitamin E decreased 34%, 46.5%. 27%, and 98%, respectively, after mice were kept for 10 weeks on vitamin E-deficient diet. PBN adducts detected by ESR in vitamin E-deficient mice provide direct evidence for in vivo free radical generation in the skin after exposure to cumene hydroperoxide.
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Affiliation(s)
- A A Shvedova
- National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA.
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Benoit JM, Gilmour CC, Heyes A, Mason RP, Miller CL. Geochemical and Biological Controls over Methylmercury Production and Degradation in Aquatic Ecosystems. ACS Symposium Series 2002. [DOI: 10.1021/bk-2003-0835.ch019] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- J. M. Benoit
- Chemistry Department, Wheaton College, Norton, MA 02766
| | - C. C. Gilmour
- The Academy of Natural Sciences, Benedict Estuarine Research Center, St. Leonard, MD 20685
| | - A. Heyes
- University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, MD 20688
| | - R. P. Mason
- University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, MD 20688
| | - C. L. Miller
- University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, MD 20688
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Abstract
Aflatoxin B1 (AFB1), a potent hepatotoxin and hepatocarcinogen, is metabolized in the liver via cytochrome P-450 to an AFB1-8,9-epoxide intermediate. The formation of the AFB1-8,9-epoxide correlates with the pathological changes observed in numerous mammalian species. Oxidative damage has been postulated to play a major role in the mechanisms associated with AFB1-induced cytotoxicity and carcinogenecity in mammalian species. The aim of this study was to detect and identify free radical intermediates from the hepatic metabolism of AFB1 in vivo. Rat bile ducts were cannulated and rats were treated simultaneously with AFB1 (3 mg/kg i.p.) and the spin trapping agent 4-POBN (alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone) (1 g/kg i.p.), and bile was collected over a period of 2 h at 20-min intervals. ESR spectroscopy was used to detect a carbon-centered radical adduct of 4-POBN in rat bile. The effect of metabolic inhibitors, such as deferoxamine mesylate (DFO), an iron chelator, and SKF 525A, a cytochrome P-450 inhibitor, on in vivo aflatoxin-induced free radical formation were also studied. It was found that there was a significant decrease in free radical formation by pre-treatment with both DFO and SKF 525A. This indicates that oxidation of AFB1 generates free radical species via CYP metabolism and an iron-mediated redox mechanism.
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Affiliation(s)
- R A Towner
- North Queensland Magnetic Resonance Centre and Department of Physiology and Pharmacology, School of Biomedical Sciences, Molecular Sciences Building, James Cook University, Townsville 4811 Queensland, Australia.
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Wheeler MD, Kono H, Yin M, Nakagami M, Uesugi T, Arteel GE, Gäbele E, Rusyn I, Yamashina S, Froh M, Adachi Y, Iimuro Y, Bradford BU, Smutney OM, Connor HD, Mason RP, Goyert SM, Peters JM, Gonzalez FJ, Samulski RJ, Thurman RG. The role of Kupffer cell oxidant production in early ethanol-induced liver disease. Free Radic Biol Med 2001; 31:1544-9. [PMID: 11744328 DOI: 10.1016/s0891-5849(01)00748-1] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.2] [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: 12/23/2022]
Abstract
Considerable evidence for a role of Kupffer cells in alcoholic liver disease has accumulated and they have recently been shown to be a predominant source of free radicals. Several approaches including pharmacological agents, knockout mice, and viral gene transfer have been used to fill critical gaps in understanding key mechanisms by which Kupffer cell activation, oxidant formation, and cytokine production lead to liver damage and subsequent pathogenesis. This review highlights new data in support of the hypothesis that Kupffer cells play a pivotal role in hepatotoxicity due to ethanol by producing oxidants via NADPH oxidase.
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Affiliation(s)
- M D Wheeler
- Laboratory of Hepatobiology and Toxicology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365, USA.
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Wheeler MD, Katuna M, Smutney OM, Froh M, Dikalova A, Mason RP, Samulski RJ, Thurman RG. Comparison of the effect of adenoviral delivery of three superoxide dismutase genes against hepatic ischemia-reperfusion injury. Hum Gene Ther 2001; 12:2167-77. [PMID: 11779401 DOI: 10.1089/10430340152710513] [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] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The purpose of this study was to investigate the effectiveness of superoxide dismutase (SOD) overexpression in an acute model of hepatic oxidative stress. Oxidative stress was established using a warm ischemia-reperfusion model, where nearly 70% of the liver was made hypoxic by clamping the hepatic artery and a branch of the portal vein for 1 hr followed by restoration of blood flow. Animals were infected i.v. with 1 x 10(9) plaque-forming units (PFU) of adenovirus containing the transgene for cytosolic Cu/Zn-SOD (Ad.SOD1), mitochondrial Mn-SOD (Ad.SOD2), extracellular Cu/Zn-SOD (Ad.SOD3), or the bacterial reporter gene for beta-galactosidase (Ad.lacZ) 3 days prior to experiments. Ad.SOD1 and Ad.SOD2 caused a three-fold increase in SOD expression and activity in liver compared to Ad.lacZ-treated control animals. Intravenous administration of Ad.SOD3 increased SOD activity slightly in serum but not in liver. Increases in serum transaminases and pathology due to ischemia-reperfusion were blunted by Ad.SOD1 and Ad.SOD2; however, extracellular SOD had no significant effect. Moreover, lipid-derived free radical adducts (a(N) = 15.65 G and a(H)(beta) = 2.78 G) were increased by ischemia-reperfusion. This effect was blunted by about 60% in Ad.SOD1- and Ad.SOD2-infected animals, but was unaffected by Ad.SOD3. However, when high doses of Ad.SOD3 (3 x 10(10) PFU) were administered. serum SOD activity was elevated three-fold and was protective against hepatic ischemia-reperfusion injury under these conditions. These data demonstrate that adenoviral delivery of superoxide dismutase can effectively reduce hepatic oxidative stress.
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Affiliation(s)
- M D Wheeler
- Department of Pharmacology and Center for Alcohol Studies, CB #7365 Mary Ellen Jones Bldg., University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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36
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Sturgeon BE, Glover RE, Chen YR, Burka LT, Mason RP. Tyrosine iminoxyl radical formation from tyrosyl radical/nitric oxide and nitrosotyrosine. J Biol Chem 2001; 276:45516-21. [PMID: 11551949 DOI: 10.1074/jbc.m106835200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [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 quenching of the Y(D)(.) tyrosyl radical in photosystem II by nitric oxide was reported to result from the formation of a weak tyrosyl radical-nitric oxide complex (Petrouleas, V., and Diner, B. A. (1990) Biochim. Biophys. Acta 1015, 131-140). This radical/radical reaction is expected to generate an electron spin resonance (ESR)-silent 3-nitrosocyclohexadienone species that can reversibly regenerate the tyrosyl radical and nitric oxide or undergo rearrangement to form 3-nitrosotyrosine. It has been proposed that 3-nitrosotyrosine can be oxidized by one electron to form the tyrosine iminoxyl radical (>C=N-O*). This proposal was put forth as a result of ESR detection of the iminoxyl radical intermediate when photosystem II was exposed to nitric oxide (Sanakis, Y., Goussias, C., Mason, R. P., and Petrouleas, V. (1997) Biochemistry 36, 1411-1417). A similar iminoxyl radical was detected in prostaglandin H synthase-2 (Gunther, M. R., Hsi, L. C., Curtis, J. F., Gierse, J. K., Marnett, L. J., Eling, T. E., and Mason, R. P. (1997) J. Biol. Chem., 272, 17086-17090). Although the iminoxyl radicals detected in the photosystem II and prostaglandin H synthase-2 systems strongly suggest a mechanism involving 3-nitrosotyrosine, the iminoxyl radical ESR spectrum was not unequivocally identified as originating from tyrosine. We report here the detection of the non-protein L-tyrosine iminoxyl radical generated by two methods: 1) peroxidase oxidation of synthetic 3-nitroso-N-acetyl-L-tyrosine and 2) peroxidase oxidation of free L-tyrosine in the presence of nitric oxide. A newly developed ESR technique that uses immobilized enzyme was used to perform the ESR experiments. Analysis of the high resolution ESR spectrum of the tyrosine iminoxyl radical generated from free tyrosine and nitric oxide reveals a 28.4-G isotropic nitrogen hyperfine coupling and a 2.2-G proton hyperfine coupling assigned to the proton originally ortho to the phenoxyl oxygen.
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Affiliation(s)
- B E Sturgeon
- Laboratory of Pharmacology and Chemistry, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
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Lawson NM, Mason RP. Concentration of mercury, methylmercury, cadmium, lead, arsenic, and selenium in the rain and stream water of two contrasting watersheds in western Maryland. Water Res 2001; 35:4039-52. [PMID: 11791833 DOI: 10.1016/s0043-1354(01)00140-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Weekly wet deposition and throughfall rain samples were collected in the Blacklick Run (BLK) and Herrington Creek Tributary (HCRT), two streams in western Maryland (MD). Samples were analyzed for total mercury (Hg), methylmercury (MMHg). arsenic (As), selenium (Se), cadmium (Cd), and Icad (Pb). Hg concentrations generally fell between 50 and 100 pM. comparable to concentrations in wet deposition measured at other MD sites. While Hg concentrations decreased with rainfall amount, a similar washout trend was not seen for MMHg. Cd, Pb, As, and Se concentrations were comparable overall to those measured in the region. Concentrations of Hg, Cd, and Pb in throughfall were similar between sites and equivalent or higher than wet deposition concentrations. As and Se concentrations were similar in throughfall at the two sites, though throughfall at BLK seemed to be punctuated with slightly higher concentrations of these two metals. Concentrations of Hg, MMHg, Cd, Pb, As, Se, and SPM were measured in monthly stream collections and compared with concentrations found in other MD rivers. In addition to the monthly collections, four storm events were sampled. These measurements demonstrate the importance of storm events in trace metal transport, especially for Hg, Pb and MMHg. For these metals, a strong correlation between metal and suspended particulate concentration was evident. Retention efficiencies of the watersheds for the metals were calculated for each watershed. Of all the metals, Hg is the most and As is the least strongly retained in the watershed.
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Affiliation(s)
- N M Lawson
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons 20688-0038, USA
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Oz OK, Hirasawa G, Lawson J, Nanu L, Constantinescu A, Antich PP, Mason RP, Tsyganov E, Parkey RW, Zerwekh JE, Simpson ER. Bone phenotype of the aromatase deficient mouse. J Steroid Biochem Mol Biol 2001; 79:49-59. [PMID: 11850207 DOI: 10.1016/s0960-0760(01)00130-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Estrogens are important for normal bone growth and metabolism. The mechanisms are incompletely understood. Thus, we have undertaken characterization of the skeletal phenotype of aromatase (ArKO) deficient mice. No abnormalities have been noted in skeletal patterning in newborns. Adult ArKO mice show decreased femur length and decreased peak Bone Mineral Density (BMD) with accelerated bone loss by 7 months of age in females. Magnetic resonance microscopy (MR) and microCT (microCT) imaging disclosed decreased cancellous connectivity and reduced cancellous bone volume in ArKO females. Bone formation rate (BFR) is increased in ArKO females and decreased in ArKO males. Estradiol therapy reverses these changes. This anabolic effect of estradiol in the male skeleton is supported by 18-F- Positron Emission Tomography (PET) imaging, which clearly demonstrates decreased spinal uptake, but marked increase after estradiol therapy. Serum IGF-1 levels are high in young female ArKO mice but low in young ArKO males. The reduced BMD in ArKO females, despite the presence of elevated serum IGF 1, suggests that other mechanism(s) are operative. There is increased B-cell lymphopoiesis in adult female ArKO bone marrow cells. These results show that ArKO mice show the effects of estrogen deficiency on bone growth, mass, metabolism, microarchitecture and the hematopoietic microenvironment.
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Affiliation(s)
- O K Oz
- Department of Radiology, UT Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
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Abstract
Coronary artery disease (CAD) is the result of atherosclerosis, a vascular disorder characterized by abnormalities in vasoconstriction and endothelial function, ultimately leading to partial or complete vessel occlusion. Because the atherosclerotic plaque is marked by changes in calcium regulation, there has been interest in a potential antiatherosclerotic role for calcium antagonists. In support of this hypothesis, a recent clinical study demonstrated in patients with CAD that treatment with the lipophilic dihydropyridine-type calcium antagonist amlodipine resulted in significantly fewer cardiovascular procedures and events. The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT) evaluated the effects of amlodipine on the development and progression of atherosclerotic lesions in coronary and carotid arteries in 825 patients with documented CAD. The results of PREVENT showed that patients receiving amlodipine had marked reductions in hospitalization for revascularization and unstable angina compared with placebo in a population consisting of either normotensive or controlled hypertensive patients. Ultrasound approaches determined that amlodipine therapy was also associated with significant slowing in carotid atherosclerosis-an important surrogate marker for CAD-over the 3-year period. This vascular-wall benefit associated with amlodipine treatment was not related to changes in blood pressure. The findings from PREVENT were consistent with a second reported study known as the Coronary Angioplasty Amlodipine Restenosis Study (CAPARES). These clinical results have led to an interest in potential plaque-stabilization properties of this lipophilic calcium antagonist. In this article, cellular and molecular mechanisms of action that may contribute to a beneficial role for a calcium antagonist in the treatment of atherosclerosis will be reviewed.
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Affiliation(s)
- R P Mason
- Membrane Biophysics Laboratory, Division of Cardiology, Department of Medicine and Biochemistry, Medical College of Pennsylvania-Hahnemann University School of Medicine, Pittsburgh, Pennsylvania, USA.
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Dikalova AE, Kadiiska MB, Mason RP. An in vivo ESR spin-trapping study: free radical generation in rats from formate intoxication--role of the Fenton reaction. Proc Natl Acad Sci U S A 2001; 98:13549-53. [PMID: 11717423 PMCID: PMC61078 DOI: 10.1073/pnas.251091098] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [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] Open
Abstract
Electron spin resonance spectroscopy has been used to study free radical generation in rats with acute sodium formate poisoning. The in vivo spin-trapping technique was used with alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN), which reacts with free radical metabolites to form radical adducts, which were detected in the bile and urine samples from Fischer rats. The use of [(13)C]-sodium formate and computer simulations of the spectra identified the 12-line spectrum as arising from the POBN/carbon dioxide anion radical adduct. The identification of POBN/*CO(2)(-) radical adduct provides direct electron spin resonance spectroscopy evidence for the formation of *CO(2)(-) radicals during acute intoxication by sodium formate, suggesting a free radical metabolic pathway. To study the mechanism of free radical generation by formate, we tested several known inhibitors. Both allopurinol, an inhibitor of xanthine oxidase, and aminobenzotriazole, a cytochrome P450 inhibitor, decreased free radical formation from formate, which may imply a dependence on hydrogen peroxide. In accord with this hypothesis, the catalase inhibitor 3-aminotriazole caused a significant increase in free radical formation. The iron chelator Desferal decreased the formation of free radicals up to 2-fold. Presumably, iron plays a role in the mechanism of free radical generation by formate via the Fenton reaction. The detection of formate free radical metabolites generated in vivo and the key role of the Fenton reaction in this process may be important for understanding the pathogenesis of both formate and methanol intoxication.
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Affiliation(s)
- A E Dikalova
- Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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Abstract
Lipoic acid and its reduced form, dihydrolipoic acid, are thought to be strong antioxidants. There are also reports of dihydrolipoic acid acting as a pro-oxidant under certain circumstances. This article reports the direct observation by ESR spectrometry of the disulfide radical anion and the spin trapping of the primary thiyl radical formed from the oxidation of dihydrolipoic acid through thiol pumping with phenol and horseradish peroxidase. The disulfide radical anion reacts rapidly with oxygen to form the reactive radical superoxide, which is also trapped. The radical species formed show a potential for pro-oxidant activity of this compound. Although antioxidants, in general, have been shown to have pro-oxidant potential, the pro-oxidant chemistry of dihydrolipoic acid has not been well characterized.
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Affiliation(s)
- C Mottley
- Department of Chemistry, Luther College, Decorah, Iowa 52101, USA
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Abstract
We recently described a novel approach to measuring regional tumor oxygen tension using (19)F nuclear magnetic resonance echo planar imaging relaxometry (FREDOM) of hexafluorobenzene. We have now applied this technique to evaluate in detail the oxygen tension dynamics in the relatively slowly growing, moderately well-differentiated Dunning prostate R3327 HI rat tumor with respect to tumor growth and respiratory challenge. Seven individual tumors were assessed repeatedly over a period of 5 weeks ( approximately 4 volume doubling times). For small tumors (<1 cm(3)), the mean pO(2) ranged from 28 to 44 Torr under baseline conditions, decreasing to less than 10 Torr when the tumors reached 5 to 6 cm(3), with a strong inverse correlation between the baseline tumor oxygen tension and the tumor size. The hypoxic fraction (defined as the percentage of the voxels with pO(2) <10 Torr) increased significantly with tumor growth. Administration of oxygen or carbogen produced a significant increase (P < 0.0001) in tumor oxygenation at all stages of tumor growth. Most interestingly, even regions of these tumors that were initially poorly oxygenated responded rapidly, and significantly, to respiratory intervention, in contrast to the behavior of the faster-growing rat prostate tumors investigated previously.
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Affiliation(s)
- D Zhao
- Advanced Radiological Sciences, Department of Radiology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9058, USA
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Abstract
7-Ketocholesterol (7-keto) is one of the major oxygenated products found in oxidized low-density lipoproteins (LDL) and in atherosclerotic plaque, where it is believed to play a role in arterial pathology. We hypothesize that direct membrane effects independent of receptor binding may mediate its biological activity. To test this, small-angle x-ray diffraction approaches were used to examine the interactions of 7-keto with other membrane components in well-defined lipid vesicles and in murine aortic smooth muscle cell membranes. These data were compared with the interactions of 25-hydroxycholesterol (25-OHC) and cholesterol. Replacement of cholesterol with 7-keto in lipid vesicles produced distinct changes in membrane structure, including a marked increase in molecular volume associated with the hydrocarbon core (+/-0-8 A from the bilayer center). Additionally, there was an increase in electron density associated with the upper acyl chain region (+/-9-21 A), corresponding to the bilayer location of the steroid nucleus of 7-keto. In contrast, 25-OHC did not appear to intercalate into the membrane hydrocarbon core and did not form separate domains. Cells grown in the presence of the 7-keto developed extracellular crystals concomitant with the formation of membrane domains having a unit cell periodicity of 35.4 or 1.4 A greater than measured with cholesterol. Domains were formed within 4 h and persisted up to 72 h, after which cells showed signs of declining viability. We conclude that 7-keto is found in a membrane location distinct from cholesterol, does not condense phospholipids as efficiently as cholesterol and is able to self-associate into discrete intrabilayer domains. While these domains may decrease its cytotoxicity by inducing the formation of sterol crystals in smooth muscle cells, they may, in a broader capacity, contribute to the sterol crystals found in advanced atherosclerotic lesions.
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Affiliation(s)
- J E Phillips
- Membrane Biophysics Laboratory, Department of Medicine, Division of Cardiology, MCP Hahnemann University, Allegheny Campus, 320 East North Avenue, Pittsburgh, PA 15212-4772, USA
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Qu W, Kasprzak KS, Kadiiska M, Liu J, Chen H, Maciag A, Mason RP, Waalkes MP. Mechanisms of arsenic-induced cross-tolerance to nickel cytotoxicity, genotoxicity, and apoptosis in rat liver epithelial cells. Toxicol Sci 2001; 63:189-95. [PMID: 11568362 DOI: 10.1093/toxsci/63.2.189] [Citation(s) in RCA: 23] [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: 11/14/2022] Open
Abstract
The purpose of the present study was to investigate the mechanism of cross-tolerance to nickel in arsenic-transformed cells. Chronic arsenite-exposed (CAsE) cells (TRL 1215 cells, which had been continuously exposed to 0.5 microM arsenite for 20 or more weeks) and control TRL 1215 cells were both exposed to nickel for 24 h, and cell viability was determined by metabolic integrity. The LC(50) for nickel was 608 +/- 32 microM in CAsE cells as compared to 232 +/- 16 microM in control cells, a 2.6-fold increase. CAsE and control cells were treated with 200 microM nickel for 4 h and cellular-free radical production was measured using ESR spectrometry. Hydroxyl radical generation was decreased in CAsE cells. Thiobarbituric acid reactive substances, indicative of lipid peroxidation, and 8-oxo-2'-deoxyguanosine, indicative of oxidative DNA damage, were reduced in CAsE cells. Flow cytometric analysis using Annexin/FITC revealed that nickel-induced apoptosis was reduced in CAsE cells. CAsE cells showed generalized resistance to oxidant-induced toxicity as evidenced by a marked reduction in sensitivity to hydrogen peroxide. Interestingly, intracellular reduced glutathione (GSH) levels were significantly increased in CAsE cells, and when GSH was depleted, CAsE cells lost their nickel resistance. The mechanism of arsenic-induced cross-tolerance to cytotoxicity, genotoxicity, and apoptosis induced by nickel appears related to a generalized resistance to oxidant-induced injury, probably based, at least in part, in increased cellular GSH levels.
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Affiliation(s)
- W Qu
- Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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45
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Abstract
It is generally recognized that tumor hypoxia has a strong influence over therapeutic outcome in the clinic. The authors have developed an oximetry approach using 19F echo planar magnetic resonance imaging-FREDOM (Fluorocarbon Relaxometry using Echoplanar imaging for Dynamic Oxygen Mapping), which reveals dynamic changes based on sequential maps of regional tumor PO2. Preclinical investigations focused on diverse sublines of the Dunning prostate R3327 tumor. As expected, intratumoral heterogeneity was considerable. However, large tumors (>3.5 cm3) were significantly less well oxygenated than smaller tumors (<2 cm3). Faster growing, less differentiated tumors were less well oxygenated than size-matched tumors of slower growing sublines. The greatest potential of this technique is the ability to follow the fate of individual tumor regions with respect to interventions. For each subline, there was a significant response to respiratory challenge with oxygen for initially well-oxygenated regions (baseline PO2 > 10 mm Hg). More interestingly, subline dependent behavior was found for initially hypoxic regions that correlated with rate of growth. The authors believe the FREDOM approach is essentially ripe for translation to the clinic. This approach could help to identify patients with hypoxic tumors and indicate the feasibility of manipulating tumor characteristics through adjuvant interventions to improve therapeutic response.
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Affiliation(s)
- D Zhao
- Department of Radiology, University of Texas Southwestern Medical Center at Dallas, Texas 75390-9058, USA
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Wheeler MD, Nakagami M, Bradford BU, Uesugi T, Mason RP, Connor HD, Dikalova A, Kadiiska M, Thurman RG. Overexpression of manganese superoxide dismutase prevents alcohol-induced liver injury in the rat. J Biol Chem 2001; 276:36664-72. [PMID: 11477087 DOI: 10.1074/jbc.m105352200] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.1] [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: 12/19/2022] Open
Abstract
Mitochondria are thought to play a major role in hepatic oxidative stress associated with alcohol-induced liver injury. Thus, the hypothesis that delivery of the mitochondrial isoform of superoxide dismutase (Mn-SOD) via recombinant adenovirus would reduce alcohol-induced liver injury was tested. Rats were given recombinant adenovirus containing Mn-SOD (Ad.SOD2) or beta-galactosidase (Ad.lacZ) and then fed alcohol enterally for 4 weeks. Mn-SOD expression and activity of Ad.SOD2 in liver mitochondria of infected animals was increased nearly 3-fold compared with Ad.lacZ-infected controls. Mitochondrial glutathione levels in Ad.lacZ-infected animals were decreased after 4 weeks of chronic ethanol, as expected, but were unchanged in Ad.SOD2-infected animals. Alanine aminotransferase was elevated significantly by ethanol, an effect that was prevented by Ad.SOD2. Moreover, pathology (e.g. the sum of steatosis, inflammation, and necrosis) was elevated dramatically by ethanol in Ad.lacZ-treated rats. This effect was also blunted in animals infected with Ad.SOD2. Neutrophil infiltration was increased about 3-fold in livers from both Ad.lacZ- and Ad.SOD2-infected rats by ethanol treatment. Moreover, ESR-detectable free radical adducts in bile were increased about 8-fold by ethanol. Using (13)C-labeled ethanol, it was determined that nearly 60% of total adducts were due to the alpha-hydroxyethyl radical adduct. This increase in radical formation was blocked completely by Ad.SOD2 infection. Furthermore, apoptosis of hepatocytes was increased about 5-fold by ethanol, an effect also blocked by Ad.SOD2. Interestingly, tumor necrosis factor-alpha mRNA was elevated to the same extent in both Ad.lacZ- and Ad.SOD2-infected animals follows ethanol exposure. These data suggest that hepatocyte mitochondrial oxidative stress is involved in alcohol-induced liver damage and likely follows Kupffer cell activation, cytokine production, and neutrophil infiltration. These results also support the hypothesis that mitochondrial oxidant production is a critical factor in parenchymal cell death caused by alcohol.
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Affiliation(s)
- M D Wheeler
- Laboratory of Hepatobiology and Toxicology, Department of Pharmacology, University of North Carolina at Chapel Hill, 27599, USA.
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47
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Abstract
Coronary artery disease (CAD) results from atherosclerosis, a systemic vascular disorder that is the leading cause of death and disability throughout much of the developed world. Because cellular changes associated with vulnerable atherosclerotic plaque are characterized by a loss of normal calcium regulation, there is strong interest in a potential antiatherosclerotic role for calcium channel blockers. This hypothesis has been supported by investigational studies conducted in well-defined cellular and animal models of atherosclerosis. In addition, several clinical studies have tested the benefit of calcium channel blockers among patients with mild-to-moderate CAD. More recent trials have shown reductions in cardiovascular events after treatment with amlodipine, a long-acting, dihydropyridine-type calcium channel blocker. The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT) demonstrated that patients with documented CAD treated with amlodipine experienced marked reductions in cardiovascular events compared with patients receiving placebo. Amlodipine also was associated with significant slowing of carotid atherosclerosis, an important surrogate marker for CAD, independent of blood pressure modification. These results have renewed interest in potential plaque stabilization properties of third-generation calcium channel blockers and their possible therapeutic role in CAD.
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Affiliation(s)
- R P Mason
- Department of Medicine, MCP Hahnemann University School of Medicine, Pittsburgh, Pennsylvania, USA.
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Yang B, Graham L, Dikalov S, Mason RP, Falck JR, Liao JK, Zeldin DC. Overexpression of cytochrome P450 CYP2J2 protects against hypoxia-reoxygenation injury in cultured bovine aortic endothelial cells. Mol Pharmacol 2001; 60:310-20. [PMID: 11455018 DOI: 10.1124/mol.60.2.310] [Citation(s) in RCA: 242] [Impact Index Per Article: 10.5] [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: 11/22/2022] Open
Abstract
CYP2J2 is abundant in human heart and its arachidonic acid metabolites, the epoxyeicosatrienoic acids (EETs), have potent vasodilatory, antiinflammatory and cardioprotective properties. This study was designed to examine the role of CYP2J2 in hypoxia-reoxygenation-induced injury in cultured bovine aortic endothelial cells (BAECs). Early passage BAECs were exposed to 24-h hypoxia followed by 4-h reoxygenation (HR). HR resulted in cell injury, as indicated by significant increases in lactate dehydrogenase (LDH) release and trypan blue stained cells (p < 0.01) and was associated with a decrease in CYP2J2 protein expression. Transfection of BAECs with the CYP2J2 cDNA resulted in increased CYP2J2 expression and arachidonic acid epoxygenase activity, compared with cells transfected with an irrelevant green fluorescent protein (GFP) cDNA. HR induced significant injury in GFP-transfected BAECs, as indicated by increases in LDH release and trypan blue-stained cells (p < 0.01); however, the HR-induced injury was markedly attenuated in CYP2J2-transfected cells (p < 0.01). HR increased cellular 8-iso-prostaglandin F(2alpha) (p < 0.05), and decreased eNOS expression, L-arginine uptake and conversion, and nitrite production (p < 0.01) in GFP-transfected BAECs. CYP2J2 transfection attenuated the HR-induced increase in 8-iso-prostaglandin F(2alpha) (p < 0.05) and decreased the amount of extracellular superoxide detected by cytochrome c reduction under normoxic conditions (p < 0.05) but did not significantly affect HR-induced decreases in eNOS expression, L-arginine uptake and conversion, and nitrite production. Treatment of BAECs with synthetic EETs and/or epoxide hydrolase inhibitors also showed protective effects against HR injury (p < 0.05). These observations suggest: (1) HR results in endothelial injury and decreased CYP2J2 expression; (2) transfection with the CYP2J2 cDNA protects against HR injury; and (3) the cytoprotective effects of CYP2J2 may be mediated, at least in part, by antioxidant effects.
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Affiliation(s)
- B Yang
- Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
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Bose-Basu B, DeRose EF, Chen YR, Mason RP, London RE. Protein NMR spin trapping with [methyl-13C(3)]-MNP: application to the tyrosyl radical of equine myoglobin. Free Radic Biol Med 2001; 31:383-90. [PMID: 11461776 DOI: 10.1016/s0891-5849(01)00599-8] [Citation(s) in RCA: 9] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Direct spin trapping studies of protein radical adducts are limited as a consequence of the long rotational correlation times and consequent broadening of the ESR resonances. It can be difficult to determine both the nature and number of adduct species present. NMR detection of reduced spin adducts represents an alternate approach which, however, is subject to the limitations of lower sensitivity and a limited capability for isolating the resonances arising from the reduced adduct from other chemistry involving the spin trap. In the present study, we have utilized [methyl-13C(3)]-MNP for the detection and analysis of tyrosyl spin adducts formed as a result of exposure of equine myoglobin to hydrogen peroxide. The methyl-13C label allows high detection sensitivity in two dimensions, narrow line widths and most significantly, removal by dialysis of unreacted spin trap as well as any nonprotein derivatives that may form. For equine myoglobin, it is found that adduct formation involves a single residue-Tyr-103 and further that adduct formation occurs at the C-3 carbon of the amino acid. HMQC-NOESY experiments further revealed the proximity of the labeled methyl groups to both the three aromatic tyrosyl protons as well as the aromatic protons of the nearby Phe-106 residue.
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Affiliation(s)
- B Bose-Basu
- National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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50
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Leaner JJ, Mason RP. The effect of thiolate organic compounds on methylmercury accumulation and redistribution in sheepshead minnows, Cyprinodon variegatus. Environ Toxicol Chem 2001; 20:1557-1563. [PMID: 11434298] [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: 05/23/2023]
Abstract
Methylmercury (CH3Hg(II)) was measured in various tissues and whole body of sheepshead minnows; Cyprinodon variegatus, following exposure to 100 ng/L methylmercury chloride (CH3HgCl) alone or in combination with one of the organic compounds cysteine (CH3Hg-Cys), thiourea (CH3Hg-Thu), or thioglycolate (CH3Hg-Thg). Overall, the CH3Hg(II) concentration in sheepshead minnows in all the treatments increased with time and was significantly different from the unspiked controls after 24 h. Addition of the organic compounds increased the bioavailability of CH3Hg(II) in the whole body of the fish after 72 h. In particular, the CH3Hg(II) concentration after CH3Hg-Thg and CH3Hg-Thu exposure was, respectively, approximately 1.3- and 1.6-fold higher than with CH3HgCl exposure. A composite of the CH3Hg(II) concentrations in the visceral organs (gill, liver, and intestine) highlighted the effect of the organic compounds, where concentrations in all mercury-thiolate treatments were significantly higher than CH3HgCl alone after 72 h. The most dramatic changes in the different tissues measured were observed in the liver, where the CH3Hg(II) concentrations in the sulfur treatments were significantly higher than the CH3HgCl treatment after 72 h. The results of this study suggest that the CH3Hg-thiolate complexes were bioavailable to sheepshead minnows and effectively induced CH3Hg(II) uptake in tissues at environmentally realistic CH3HgCl concentrations.
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Affiliation(s)
- J J Leaner
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, PO Box 38, Solomons, Maryland 20688, USA
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