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Hendrix B, Zheng W, Bauer MJ, Havecker ER, Mai JT, Hoffer PH, Sanders RA, Eads BD, Caruano-Yzermans A, Taylor DN, Hresko C, Oakes J, Iandolino AB, Bennett MJ, Deikman J. Topically delivered 22 nt siRNAs enhance RNAi silencing of endogenous genes in two species. Planta 2021; 254:60. [PMID: 34448043 PMCID: PMC8390415 DOI: 10.1007/s00425-021-03708-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 06/05/2021] [Accepted: 08/16/2021] [Indexed: 05/23/2023]
Abstract
MAIN CONCLUSION 22 nt siRNAs applied to leaves induce production of transitive sRNAs for targeted genes and can enhance local silencing. Systemic silencing was only observed for a GFP transgene. RNA interference (RNAi) is a gene silencing mechanism important in regulating gene expression during plant development, response to the environment and defense. Better understanding of the molecular mechanisms of this pathway may lead to future strategies to improve crop traits of value. An abrasion method to deliver siRNAs into leaf cells of intact plants was used to investigate the activities of 21 and 22 nt siRNAs in silencing genes in Nicotiana benthamiana and Amaranthus cruentus. We confirmed that both 21 and 22 nt siRNAs were able to silence a green fluorescent protein (GFP) transgene in treated leaves of N. benthamiana, but systemic silencing of GFP occurred only when the guide strand contained 22 nt. Silencing in the treated leaves of N. benthamiana was demonstrated for three endogenous genes: magnesium cheletase subunit I (CHL-I), magnesium cheletase subunit H (CHL-H), and GENOMES UNCOUPLED4 (GUN4). However, systemic silencing of these endogenous genes was not observed. Very high levels of transitive siRNAs were produced for GFP in response to treatment with 22 nt siRNAs but only low levels were produced in response to a 21 nt siRNA. The endogenous genes tested also produced transitive siRNAs in response to 22 nt siRNAs. 22 nt siRNAs produced greater local silencing phenotypes than 21 nt siRNAs for three of the genes. These special properties of 22 nt siRNAs were also observed for the CHL-H gene in A. cruentus. These experiments suggest a functional role for transitive siRNAs in amplifying the RNAi response.
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Affiliation(s)
- Bill Hendrix
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
- Bayer U.S. LLC, Research and Development, Crop Science, Biologics Pest Control, 890 Embarcadero Drive, West Sacramento, CA, 95605, USA
| | - Wei Zheng
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Matthew J Bauer
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Ericka R Havecker
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Jennifer T Mai
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Paul H Hoffer
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
- California Governor's Office of Emergency Services, 3650 Schriever Avenue, Mather, CA, 95655, USA
| | - Rick A Sanders
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Brian D Eads
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | | | - Danielle N Taylor
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Chelly Hresko
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Janette Oakes
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | | | - Michael J Bennett
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Jill Deikman
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA.
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2
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Henderson A, Paterson DL, Chatfield MD, Tambyah PA, Lye DC, De PP, Lin RTP, Chew KL, Yin M, Lee TH, Yilmaz M, Cakmak R, Alenazi TH, Arabi YM, Falcone M, Bassetti M, Righi E, Ba R, Kanj SS, Bhally H, Iredell J, Mendelson M, Boyles TH, Looke DFM, Runnegar NJ, Miyakis S, Walls G, Ai Khamis M, Zikri A, Crowe A, Ingram PR, Daneman NN, Griffin P, Athan E, Roberts L, Beatson SA, Peleg AY, Cottrell KK, Bauer MJ, Tan E, Chaw K, Nimmo GR, Harris-Brown T, Harris PNA. Association between minimum inhibitory concentration, beta-lactamase genes and mortality for patients treated with piperacillin/tazobactam or meropenem from the MERINO study. Clin Infect Dis 2020; 73:e3842-e3850. [PMID: 33106863 DOI: 10.1093/cid/ciaa1479] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [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: 12/08/2019] [Indexed: 11/12/2022] Open
Abstract
INTRODUCTION This study aims to assess the association of piperacillin/tazobactam and meropenem minimum inhibitory concentration (MIC) and beta-lactam resistance genes with mortality in the MERINO trial. METHODS Blood culture isolates from enrolled patients were tested by broth microdilution and whole genome sequencing at a central laboratory. Multivariate logistic regression was performed to account for confounders. Absolute risk increase for 30-day mortality between treatment groups was calculated for the primary analysis (PA) and the microbiologic assessable (MA) populations. RESULTS 320 isolates from 379 enrolled patients were available with susceptibility to piperacillin/tazobactam 94% and meropenem 100%. The piperacillin/tazobactam non-susceptible breakpoint (MIC > 16 mg/L) best predicted 30-day mortality after accounting for confounders (odds ratio 14.9, 95% CI 2.8 - 87.2). The absolute risk increase for 30-day mortality for patients treated with piperacillin/tazobactam compared with meropenem was 9% (95% CI 3% - 15%) and 8% (95% CI 2% - 15%) for the original PA population and the post-hoc MA populations, which reduced to 5% (95% CI -1% - 10%) after excluding strains with piperacillin/tazobactam MIC values > 16 mg/L. Isolates co-harboring ESBL and OXA-1 genes were associated with elevated piperacillin/tazobactam MICs and the highest risk increase in 30-mortality of 14% (95% CI 2% - 28%). CONCLUSION After excluding non-susceptible strains, the 30-day mortality difference was from the MERINO trial was less pronounced for piperacillin/tazobactam. Poor reliability in susceptibility testing performance for piperacillin/tazobactam and the high prevalence of OXA co-harboring ESBLs suggests meropenem remains the preferred choice for definitive treatment of ceftriaxone non-susceptible E. coli and Klebsiella.
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Affiliation(s)
- A Henderson
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia.,Infection Management Services, Princess Alexandra Hospital, Brisbane, QLD
| | - D L Paterson
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia
| | - M D Chatfield
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia
| | - P A Tambyah
- Department of Infectious Diseases, National University Hospital, Singapore
| | - D C Lye
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Department of Infectious Diseases, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore,Hospital, Singapore
| | - P P De
- Department of Laboratory Medicine, Tan Tock Seng Hospital, Singapore
| | - R T P Lin
- Department of Laboratory Medicine, National University Hospital, Singapore
| | - K L Chew
- Division of Microbiology, National University Hospital, Singapore
| | - M Yin
- Department of Infectious Diseases, National University Hospital, Singapore
| | - T H Lee
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Department of Infectious Diseases, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - M Yilmaz
- Department of Infectious Diseases and Clinical Microbiology, School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| | - R Cakmak
- Department of Infectious Diseases and Clinical Microbiology, School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| | - T H Alenazi
- King Saud Bin Abdulaziz University for Health Sciences and King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Y M Arabi
- King Saud Bin Abdulaziz University for Health Sciences and King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - M Falcone
- Division of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Pisa, Italy
| | - M Bassetti
- Infectious Diseases Clinic, Department of Health Sciences, University of Genoa and Ospedale Policlinico San Martino Genoa, Italy
| | - E Righi
- Infectious Diseases Clinic, Department of Medicine University of Udine and Santa Maria Misericordia Hospital, Udine, Italy.,Infectious Diseases, Department of Diagnostics and Public Health, University of Verona, Verona, Italy
| | - Rogers Ba
- Monash University, Centre for Inflammatory Diseases, Victoria, Australia.,Monash Infectious Diseases, Monash Health, Victoria, Australia
| | - S S Kanj
- Department of Internal Medicine, Division of Infectious Diseases, American University of Beirut Medical Center, Beirut, Lebanon
| | - H Bhally
- Department of Medicine and Infectious Diseases, North Shore Hospital, Auckland
| | - J Iredell
- Marie Bashir Institute for Infectious Disease and Biosecurity, University of Sydney, Sydney, Australia.,Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, Australia
| | - M Mendelson
- Division of Infectious Diseases & HIV Medicine, Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - T H Boyles
- Division of Infectious Diseases & HIV Medicine, Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - D F M Looke
- Infection Management Services, Princess Alexandra Hospital, Brisbane, QLD.,University of Queensland, Brisbane, Australia
| | - N J Runnegar
- Infection Management Services, Princess Alexandra Hospital, Brisbane, QLD.,University of Queensland, Brisbane, Australia
| | - S Miyakis
- School of Medicine, University of Wollongong, Wollongong, New South Wales, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia.,Department of Infectious Diseases, Wollongong Hospital, Wollongong, New South Wales, Australia
| | - G Walls
- Department of Infectious Diseases, Middlemore Hospital, Auckland, New Zealand
| | - M Ai Khamis
- King Fahad Specialist Hospital, Dammam, Saudi Arabia
| | - A Zikri
- King Fahad Specialist Hospital, Dammam, Saudi Arabia
| | - A Crowe
- Department of Infectious Diseases, St Vincent's Hospital, Melbourne, Australia.,Department of Microbiology, St Vincent's Hospital, Melbourne, Australia
| | - P R Ingram
- School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, Australia.,Department of Infectious Diseases, Fiona Stanley Hospital, Murdoch , Australia.,Department of Microbiology, PathWest Laboratory Medicine, Perth, Western Australia
| | - N N Daneman
- Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada
| | - P Griffin
- University of Queensland, Brisbane, Australia.,Department of Medicine and Infectious Diseases, Mater Hospital and Mater Medical Research Institute, Brisbane, Australia.,QIMR Berghofer, Brisbane, Queensland, Australia
| | - E Athan
- Department of Infectious Diseases, Barwon Health and Deakin University, Geelong, Victoria, Australia
| | - L Roberts
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Queensland, Australia
| | - S A Beatson
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Queensland, Australia
| | - A Y Peleg
- Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia.,Department of Microbiology, Monash University, Clayton, Australia
| | - K K Cottrell
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia
| | - M J Bauer
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia
| | - E Tan
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia
| | - K Chaw
- Department of Microbiology, Pathology Queensland, Toowoomba Laboratory, Australia.,Department of Microbiology, Mater Pathology, Australia.,Infectious Diseases Department, Redcliffe Hospital, Australia
| | - G R Nimmo
- Department of Microbiology, Pathology Queensland, Royal Brisbane and Women's Hospital, Brisbane, Australia
| | - T Harris-Brown
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia
| | - P N A Harris
- University of Queensland, UQ Centre for Clinical Research, Brisbane, Australia.,Department of Microbiology, Pathology Queensland, Royal Brisbane and Women's Hospital, Brisbane, Australia
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Bauer MJ, Stone-Garza KK, Croom D, Andreoli C, Woodson P, Graf PCF, Maves RC. Shewanella algae Infections in United States Naval Special Warfare Trainees. Open Forum Infect Dis 2019; 6:ofz442. [PMID: 31696143 DOI: 10.1093/ofid/ofz442] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [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: 08/27/2019] [Accepted: 10/04/2019] [Indexed: 11/12/2022] Open
Abstract
Shewanella infections are uncommon in immunocompetent hosts. We report 6 cases of Shewanella algae infection in young, healthy Naval Special Warfare trainees in San Diego during 2 consecutive El Niño seasons, defining a unique population at risk and adding to the epidemiologic understanding of this potentially virulent organism.
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Affiliation(s)
- Matthew J Bauer
- Division of Infectious Diseases, Department of Internal Medicine, Naval Medical Center, San Diego, California, USA
| | - Kristi K Stone-Garza
- Division of Infectious Diseases, Department of Internal Medicine, Naval Medical Center, San Diego, California, USA
| | - Daniel Croom
- Naval Special Warfare Center, Naval Amphibious Base Coronado, California, USA
| | - Cheryl Andreoli
- Navy Environmental and Preventive Medicine Unit FIVE, San Diego, California, USA
| | - Peter Woodson
- Naval Special Warfare Center, Naval Amphibious Base Coronado, California, USA
| | - Paul C F Graf
- Division of Microbiology, Department of Laboratory Medicine, Naval Medical Center, San Diego, California, USA
| | - Ryan C Maves
- Division of Infectious Diseases, Department of Internal Medicine, Naval Medical Center, San Diego, California, USA
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4
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van Assen M, De Cecco CN, Eid M, von Knebel Doeberitz P, Scarabello M, Lavra F, Bauer MJ, Mastrodicasa D, Duguay TM, Zaki B, Lo GG, Choe YH, Wang Y, Sahbaee P, Tesche C, Oudkerk M, Vliegenthart R, Schoepf UJ. Prognostic value of CT myocardial perfusion imaging and CT-derived fractional flow reserve for major adverse cardiac events in patients with coronary artery disease. J Cardiovasc Comput Tomogr 2019; 13:26-33. [PMID: 30796003 DOI: 10.1016/j.jcct.2019.02.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/11/2019] [Indexed: 01/25/2023]
Abstract
OBJECTIVES The purpose of this study was to analyze the prognostic value of dynamic CT perfusion imaging (CTP) and CT derived fractional flow reserve (CT-FFR) for major adverse cardiac events (MACE). METHODS 81 patients from 4 institutions underwent coronary computed tomography angiography (CCTA) with dynamic CTP imaging and CT-FFR analysis. Patients were followed-up at 6, 12, and 18 months after imaging. MACE were defined as cardiac death, nonfatal myocardial infarction, unstable angina requiring hospitalization, or revascularization. CT-FFR was computed for each major coronary artery using an artificial intelligence-based application. CTP studies were analyzed per vessel territory using an index myocardial blood flow, the ratio between territory and global MBF. The prognostic value of CCTA, CT-FFR, and CTP was investigated with a univariate and multivariate Cox proportional hazards regression model. RESULTS 243 vessels in 81 patients were interrogated by CCTA with CT-FFR and 243 vessel territories (1296 segments) were evaluated with dynamic CTP imaging. Of the 81 patients, 25 (31%) experienced MACE during follow-up. In univariate analysis, a positive index-MBF resulted in the largest risk for MACE (HR 11.4) compared to CCTA (HR 2.6) and CT-FFR (HR 4.6). In multivariate analysis, including clinical factors, CCTA, CT-FFR, and index-MBF, only index-MBF significantly contributed to the risk of MACE (HR 10.1), unlike CCTA (HR 1.2) and CT-FFR (HR 2.2). CONCLUSION Our study provides initial evidence that dynamic CTP alone has the highest prognostic value for MACE compared to CCTA and CT-FFR individually or a combination of the three, independent of clinical risk factors.
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Affiliation(s)
- M van Assen
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, Groningen, the Netherlands.
| | - C N De Cecco
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Department of Radiology, Emory University, Atlanta, Georgia, USA.
| | - M Eid
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - P von Knebel Doeberitz
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - M Scarabello
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - F Lavra
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - M J Bauer
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - D Mastrodicasa
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - T M Duguay
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - B Zaki
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
| | - G G Lo
- Department of Diagnostic and Interventional Radiology, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, China.
| | - Y H Choe
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
| | - Y Wang
- Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
| | | | - Christian Tesche
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Department of Cardiology and Intensive Care Medicine, Heart Center Munich-Bogenhausen, Munich, Germany.
| | - M Oudkerk
- University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, Groningen, the Netherlands.
| | - R Vliegenthart
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, Groningen, the Netherlands; University of Groningen, University Medical Center Groningen, Departments of Radiology, Groningen, the Netherlands.
| | - U J Schoepf
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
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Bauer MJ, Wen X, Tiwari P, Arnold DP, Andrew JS. Magnetic field sensors using arrays of electrospun magnetoelectric Janus nanowires. Microsyst Nanoeng 2018; 4:37. [PMID: 31057925 PMCID: PMC6277440 DOI: 10.1038/s41378-018-0038-x] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 10/04/2018] [Accepted: 10/17/2018] [Indexed: 05/31/2023]
Abstract
The fabrication and characterization of the first magnetoelectric sensors utilizing arrays of Janus magnetoelectric composite nanowires composed of barium titanate and cobalt ferrite are presented. By utilizing magnetoelectric nanowires suspended across electrodes above the substrate, substrate clamping is reduced when compared to layered thin-film architectures; this results in enhanced magnetoelectric coupling. Janus magnetoelectric nanowires are fabricated by sol-gel electrospinning, and their length is controlled through the electrospinning and calcination conditions. Using a directed nanomanufacturing approach, the nanowires are then assembled onto pre-patterned metal electrodes on a silicon substrate using dielectrophoresis. Using this process, functional magnetic field sensors are formed by connecting many nanowires in parallel. The observed magnetic field sensitivity from the parallel array of nanowires is 0.514 ± .027 mV Oe-1 at 1 kHz, which translates to a magnetoelectric coefficient of 514 ± 27 mV cm-1 Oe-1.
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Affiliation(s)
- Matthew J. Bauer
- Dept. of Materials Science and Engineering, University of Florida, Gainesville, FL 32611-6400 USA
| | - Xiao Wen
- Dept. of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611-6200 USA
| | - Prabal Tiwari
- Dept. of Materials Science and Engineering, University of Florida, Gainesville, FL 32611-6400 USA
| | - David P. Arnold
- Dept. of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611-6200 USA
| | - Jennifer S. Andrew
- Dept. of Materials Science and Engineering, University of Florida, Gainesville, FL 32611-6400 USA
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6
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Berdahl JP, Khatana AK, Katz LJ, Herndon L, Layton AJ, Yu TM, Bauer MJ, Cantor LB. Cost-comparison of two trabecular micro-bypass stents versus selective laser trabeculoplasty or medications only for intraocular pressure control for patients with open-angle glaucoma. J Med Econ 2017; 20:760-766. [PMID: 28471282 DOI: 10.1080/13696998.2017.1327439] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIM Patients with open-angle glaucoma (OAG) whose intraocular pressure is not adequately controlled by one medication have several treatment options in the US. This analysis evaluated direct costs of unilateral eye treatment with two trabecular micro-bypass stents (two iStents) compared to selective laser trabeculoplasty (SLT) or medications only. MATERIALS AND METHODS A population-based, annual state-transition, probabilistic, cost-of-care model was used to assess OAG-related costs over 5 years. Patients were modeled to initiate treatment in year zero with two iStents, SLT, or medications only. In years 1-5, patients could remain on initial treatment or move to another treatment option(s), or filtration surgery. Treatment strategy change probabilities were identified by a clinician panel. Direct costs were included for drugs, procedures, and complications. RESULTS The projected average cumulative cost at 5 years was lower in the two-stent treatment arm ($4,420) compared to the SLT arm ($4,730) or medications-only arm ($6,217). Initial year-zero costs were higher with two iStents ($2,810) than with SLT ($842) or medications only ($996). Average marginal annual costs in years 1-5 were $322 for two iStents, $777 for SLT, and $1,044 for medications only. The cumulative cost differences between two iStents vs SLT or medications only decreased over time, with breakeven by 5 or 3 years post-initiation, respectively. By year 5, cumulative savings with two iStents over SLT or medications only was $309 or $1,797, respectively. LIMITATIONS This analysis relies on clinical expert panel opinion and would benefit from real-world evidence on use of multiple procedures and treatment switching after two-stent treatment, SLT, or polypharmaceutical initial approaches. CONCLUSIONS Despite higher costs in year zero, annual costs thereafter were lowest in the two-stent treatment arm. Two-stent treatment may reduce OAG-related health resource use, leading to direct savings, especially over medications only or at longer time horizons.
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Affiliation(s)
| | | | - L Jay Katz
- c Wills Eye Hospital, Thomas Jefferson University , Philadelphia , PA , USA
- d Glaukos Corporation , Laguna Hills , CA , USA
| | | | | | - Tiffany M Yu
- f Quorum Consulting, Inc , San Francisco , CA , USA
| | | | - Louis B Cantor
- g Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine , Indianapolis , IN , USA
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7
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Bauer MJ, Fischer RL. Genome demethylation and imprinting in the endosperm. Curr Opin Plant Biol 2011; 14:162-7. [PMID: 21435940 PMCID: PMC3082360 DOI: 10.1016/j.pbi.2011.02.006] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [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: 10/22/2010] [Revised: 01/07/2011] [Accepted: 02/21/2011] [Indexed: 05/19/2023]
Abstract
Imprinting occurs in the endosperm of flowering plants. The endosperm, a product of central cell fertilization, is critical for embryo and seed development. Imprinting in the endosperm is mainly due to the inherited differences in gamete epigenetic composition. Studies have also shown that there are differences in genomic DNA methylation patterns between embryo and endosperm. Examining those differences, along with mutations in the DNA demethylase gene DEMETER, gives insight into the number of imprinted genes and how an antagonistic relationship between TE defense and gene regulation could evolutionarily affect imprinting establishment. Finally, studies demonstrate that DEMETER demethylase activity influences endosperm chromatin composition, and could possibly enhance DNA de novo methylation activity.
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Affiliation(s)
| | - Robert L. Fischer
- Corresponding author: , Telephone: +1-510-642-1314, Fax: +1-510-642-4995
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8
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Abstract
Gene imprinting, the differential expression of maternal and paternal alleles, independently evolved in mammals and in flowering plants. A unique feature of flowering plants is a double-fertilization event in which the sperm fertilize not only the egg, which forms the embryo, but also the central cell, which develops into the endosperm (an embryo-supporting tissue). The distinctive mechanisms of gene imprinting in the endosperm, which involve DNA demethylation and histone methylation, begin in the central cell and sperm prior to fertilization. Flowering plants might have coevolved double fertilization and imprinting to prevent parthenogenetic development of the endosperm.
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Affiliation(s)
- Jin Hoe Huh
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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9
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Abstract
Imprinting occurs in the endosperm of flowering plants. Endosperm, produced by fertilization of the central cell in the female gametophyte, is essential for embryo and seed development. Several imprinted genes play an important role in endosperm development. The mechanism of gene imprinting involves DNA methylation and histone modification. DNA methylation is actively removed at the imprinted alleles to be activated. Histone methylation mediated by the Polycomb group complex provides another layer of epigenetic regulation at the silenced alleles. Endosperm gene imprinting can be uncoupled from seed development when fertilization of the central cell is prevented. Imprinting may be a mechanism to ensure fertilization of the central cell thereby preventing parthenogenic development of the endosperm.
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Affiliation(s)
- Jin Hoe Huh
- University of California at Berkeley, Plant & Microbial Biology Department, Berkeley, CA 94720-3102, USA
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10
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Lamb JC, Danilova T, Bauer MJ, Meyer JM, Holland JJ, Jensen MD, Birchler JA. Single-gene detection and karyotyping using small-target fluorescence in situ hybridization on maize somatic chromosomes. Genetics 2007; 175:1047-58. [PMID: 17237520 PMCID: PMC1840074 DOI: 10.1534/genetics.106.065573] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [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: 01/28/2023] Open
Abstract
Combined with a system for identifying each of the chromosomes in a genome, visualizing the location of individual genetic loci by fluorescence in situ hybridization (FISH) would aid in assembling physical and genetic maps. Previously, large genomic clones have been successfully used as FISH probes onto somatic chromosomes but this approach is complicated in species with abundant repetitive elements. In this study, repeat-free portions of sequences that were anchored to particular chromosomes including genes, gene clusters, large cDNAs, and portions of BACs obtained from public databases were used to label the corresponding physical location using FISH. A collection of probes that includes at least one marker on each chromosome in the maize complement was assembled, allowing a small-target karyotyping system to be developed. This set provides the foundation onto which additional loci could be added to strengthen further the ability to perform chromosomal identification in maize and its relatives. The probes were demonstrated to produce signals in several wild relatives of maize, including Zea luxurians, Z. diploperennis, and Tripsacum dactyloides.
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Affiliation(s)
- Jonathan C Lamb
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA
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11
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Bauer MJ, Birchler JA. Organization of endoreduplicated chromosomes in the endosperm of Zea mays L. Chromosoma 2006; 115:383-94. [PMID: 16741707 DOI: 10.1007/s00412-006-0068-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [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: 11/19/2005] [Revised: 04/10/2006] [Accepted: 04/12/2006] [Indexed: 10/24/2022]
Abstract
The chromosomes of the maize endosperm proceed through an endoreduplication phase in later stages of development. Endoreduplication is a process in which the cell cycle continues DNA synthesis but does not proceed through cytokinesis. When this occurs, the normally triploid endosperm cell can reach ploidy levels greater than 200x in some lines of maize. In this work, we examined the structure of the endoreduplicated chromosomes. Previous cytological work has indicated that, although the DNA content per cell increases, the number of nucleoli and knobs remains the same. Using fluorescence in situ hybridization and slot blot techniques, we show that the highly repetitive heterochromatic areas both on the A and B chromosomes, as well as several actively transcribed genes, are endoreduplicated. This result suggests that the entire genome follows that same trend. Further evidence shows that the various chromatin strands stay associated throughout the length of the chromosomes after they have been replicated, and that the DNA at the centromeric and knob regions is more tightly associated than the other regions of the chromosomes. Interploidy crosses between diploid and tetraploid derivatives of the same inbred exhibit changes in the chromatin organization of centromeres and heterochromatic knobs.
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Affiliation(s)
- Matthew J Bauer
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA
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12
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Kato A, Zheng YZ, Auger DL, Phelps-Durr T, Bauer MJ, Lamb JC, Birchler JA. Minichromosomes derived from the B chromosome of maize. Cytogenet Genome Res 2005; 109:156-65. [PMID: 15753572 DOI: 10.1159/000082395] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Accepted: 02/20/2004] [Indexed: 11/19/2022] Open
Abstract
Fourteen minichromosomes derived from the B chromosome of maize are described. The centromeric region of the B chromosome contains a specific repetitive DNA element called the B repeat. This sequence was used to determine the transmission frequency of the different types of minichromosomes over several generations via Southern blot analysis at each generation. In general, the minichromosomes have transmission rates below the theoretical 50% frequency of a univalent chromosome. The gross structure of each minichromosome was determined using fluorescence in situ hybridization (FISH) on root tip chromosome spreads. The presence of the B centromeric repeat and of the adjacent heterochromatic knob sequences was determined for each minichromosome. In two cases, the amount of the centromeric knob repeat is increased relative to the progenitor chromosome. Other isolates have reduced or undetectable levels of the knob sequence. Potential uses of the minichromosomes are discussed.
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Affiliation(s)
- A Kato
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211-7400, USA
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13
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Ream TS, Strobel J, Roller B, Auger DL, Kato A, Halbrook C, Peters EM, Theuri J, Bauer MJ, Addae P, Dioh W, Staub JM, Gilbertson LA, Birchler JA. A test for ectopic exchange catalyzed by Cre recombinase in maize. Theor Appl Genet 2005; 111:378-85. [PMID: 15912343 DOI: 10.1007/s00122-005-2031-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2004] [Accepted: 04/06/2005] [Indexed: 05/02/2023]
Abstract
A maize line expressing Cre recombinase as well as the recipient line without the transgene were assayed for evidence of ectopic recombination within the maize genome. Such a test is valuable for understanding the action of Cre as well as for its use to recombine two target lox sites present in the chromosomes. Pollen examination and seed set tests of material expressing Cre provided no evidence of ectopic recombination, which would be manifested in the production of translocations or inversions and result in pollen abortion and reduced seed set. Root-tip chromosome karyotype analysis was also performed on material with and without Cre expression. Chromosomal aberrations in Cre+ material were not observed above the background level.
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Affiliation(s)
- Thomas S Ream
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, 65211, USA
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Abstract
The purpose of this exploratory study was to examine the perceptions of 115 female spouse caregivers of early to moderate stage dementia patients. Based on patients' cognitive status, cross-sectional comparisons of two groups of caregiving wives were conducted. No group differences were found in measures of caregiver burden, depression, or personal gain. However, wives of patients with greater cognitive impairment experienced lower levels of mastery and more relational deprivation when compared to wives of patients with higher mental status. Supportive approaches might be directed toward helping early dementia caregivers restructure their understanding of, and participation in, their marital relationships in anticipation of changes ahead. Interventions aimed at enhancing a caregiver's sense of personal mastery may help reduce the negative effects of dementia on caregivers' well-being.
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Affiliation(s)
- M J Bauer
- Research Service and Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, Minneapolis, Minnesota, USA
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15
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Sussman HE, Bauer MJ, Shi X, Judice SA, Albertini RJ, Walker VE. Transplacental mutagenicity of N-ethyl-N-nitrosourea at the hprt locus in T-lymphocytes of exposed B6C3F1 mice. Environ Mol Mutagen 2001; 38:30-37. [PMID: 11473385 DOI: 10.1002/em.1047] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Previous studies have compared age-related differences in total mutagenic burden in mice of differing age (preweanling, weanling, or young adult) after single intraperitoneal (i.p.) injections of ethylnitrosourea (ENU). The purpose of the present investigation was to determine the effects of time elapsed since treatment on the frequency of hprt mutant T-cells (Mf) from mice treated transplacentally with single acute vs. multiple split doses of ENU. To this end, pregnant C57BL/6 mice (n = 13-16/group), which had been bred to C3H males, were given i.p. injections of 40 mg ENU/kg bw in a single dose on day 18 of gestation, in a split dose of 6 mg ENU/kg bw on days 12 through 18 of gestation, or DMSO vehicle alone. Groups of pups were necropsied on days 10, 13, 15 (single dose only), 17, 20, 40, and 70 postpartum for T-cell isolations and hprt Mf measurements using the T-cell cloning assay. The time required to reach maximum Mfs in T-cells isolated from thymus of transplacentally treated animals was 2 weeks, the same time span as previously observed after ENU treatment of adult, weanling, and preweanling mice. Mfs in T-cells isolated from spleens of control animals averaged 2.1 +/- 0.3 (SE) x 10(-6). In spleens of mice treated transplacentally with ENU in a single dose, Mfs reached a maximum at 15 days postpartum [84.7 +/- 15.8 (SE) x 10(-6)] and decreased to lower but still elevated levels at 40 days postpartum. In spleens of mice treated transplacentally with ENU in a split dose, Mfs reached a maximum at 13 days postpartum [74.0 +/- 16.3 (SE) x 10(-6)] and decreased to background levels at 40 days postpartum. The areas under the curves describing the change in hprt Mfs over time for ENU-treated vs. control mice estimate the mutagenic potency for transplacental single- and split-dose exposures to be 1.9 and 0.8 x 10(3), respectively. Comparison of the mutagenic potency estimates for mice exposed to ENU in utero to 4-week-old mice given a similar dose of the same lot number of ENU indicates that the mouse is more susceptible to ENU-induced mutagenesis during fetal life.
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Affiliation(s)
- H E Sussman
- Wadsworth Center, New York State Department of Health, Albany, New York,, USA
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16
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Meng Q, Singh N, Heflich RH, Bauer MJ, Walker VE. Comparison of the mutations at Hprt exon 3 of T-lymphocytes from B6C3F1 mice and F344 rats exposed by inhalation to 1,3-butadiene or the racemic mixture of 1,2:3,4-diepoxybutane. Mutat Res 2000; 464:169-84. [PMID: 10648904 DOI: 10.1016/s1383-5718(99)00157-6] [Citation(s) in RCA: 24] [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: 11/17/2022]
Abstract
Experiments were conducted to define the spectra of mutations occurring in Hprt exon 3 of T-cells isolated from spleens of female B6C3F1 mice and F344 rats exposed by inhalation to 1,3-butadiene (BD) or its reactive metabolite, (+/-)-diepoxybutane (DEB). Hprt mutant frequencies (Mfs) in BD-exposed (1250 ppm for 2 weeks or 625 ppm for 4 weeks; 6 h/day, 5 days/week) and DEB-exposed (2 or 4 ppm for 4 weeks or 5 ppm for 6 weeks; 6 h/day, 5 days/week) mice and rats were significantly increased over concurrent control values. Mutant T-cell colonies from control and treated animals were screened for mutations in Hprt exon 3 using PCR amplification of genomic DNA and denaturing gradient gel electrophoresis, followed by sequence analysis. Exon 3 mutations were found at the following frequencies: 20/394 (5%) in control mice, 56/712 (8%) in BD-exposed mice, 59/1178 (5%) in BD-exposed rats, 66/642 (10%) in DEB-exposed mice, and 51/732 (7%) in DEB-exposed rats. Mutations in exposed animals included base substitutions, small deletions (1 to 74 bp), and small insertions (1 to 8 bp), with base substitutions predominating. Among the types of base substitutions observed in mice, the proportions of G.C-->A.T transitions (p=0.035, Fisher's Exact Test) and G.C-->C.G transversions (p=0.05) were significantly different in control vs. BD-exposed animals. Given the small number of exon 3 mutants analyzed, there was a high degree of overlap in the mutational spectra between BD-exposed mice and rats, between BD- and DEB-exposed mice, and between BD- and DEB-exposed rats in terms of the sites with base substitutions, the mutations found at those mutated sites, the relative occurrence of the most frequently observed base substitutions, and the occurrence of a consistent strand bias for the most frequently observed base substitutions. The spectra data suggest that adduction of both G.C and A.T bps is important in the induction of in vivo mutations by BD metabolites in exposed mice and rats.
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Affiliation(s)
- Q Meng
- Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, NY, USA
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17
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Walker VE, Jones IM, Crippen TL, Meng Q, Walker DM, Bauer MJ, Reilly AA, Tates AD, Nakamura J, Upton PB, Skopek TR. Relationships between exposure, cell loss and proliferation, and manifestation of Hprt mutant T cells following treatment of preweanling, weanling, and adult male mice with N-ethyl-N-nitrosourea. Mutat Res 1999; 431:371-88. [PMID: 10636002 DOI: 10.1016/s0027-5107(99)00180-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Experiments were performed to characterize the age-related patterns of appearance and frequency of hypoxanthine-guanine phosphoribosyl transferase (Hprt) mutant T lymphocytes in thymus and spleen following exposure of preweanling (12-day-old), weanling (22-day-old), and young adult (8-week-old) male B6C3F1 mice to ethylnitrosourea (ENU). Mice were given single i.p. injections of 0 or 40 mg ENU/kg and then groups of animals were necropsied from 2 h to 116 days after treatment to examine the relationships between exposure, cell loss and proliferation, and the frequency of Hprt mutant T cells in thymus and spleen. Hprt mutant frequency (Mf) data for thymus of ENU-exposed (0, 11.7, 35, 58, or 72 mg/kg, or five weekly doses of 1.7 mg/kg i.p.) male C57BL/6 mice (12- or 62-week-old), obtained during an earlier study of spleen cells [I.M. Jones, K. Burkhart-Schultz, C.L. Strout, T.L. Crippen, Factors that affect the frequency of thioguanine-resistant lymphocytes in mice following exposure to ethylnitrosourea, Environ. Mutagen, 9 (1987) 317-329.], were compared to results in B6C3F1 mice. Isolated T cells were cultured in the presence of mitogen, growth factor, and 6-thioguanine to detect Hprt mutants. The time required to achieve maximum Mfs in thymus was uniformly found at 2 weeks after ENU treatment, while the times needed to reach peak values in spleen were proportional to animal age at treatment. These data indicate that age-related differences in the appearance of Hprt mutant cells in spleen are largely defined by the physiologically based, age-dependent trafficking of mutant cells from or through the thymus. Three modes of handling the resulting Hprt Mf data were evaluated: (i) comparing the Mfs at a single time point, (ii) comparing the maximum Mfs observed, and (iii) comparing the change in Mfs over time (or the mutant T cell 'manifestation' curves in treated vs. control mice) in each age group post-exposure. Measuring the Mfs in spleen at multiple time points after cessation of exposure and integrating the frequency of mutants as a function of time appeared to be the superior method for comparing mutagenic responses in different age groups. Some of the underlying assumptions of this approach, as well as its strengths and weaknesses, are discussed.
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Affiliation(s)
- V E Walker
- Department of Pathology, University of North Carolina, Chapel Hill 27599, USA.
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18
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Sussman HE, Olivero OA, Meng Q, Pietras SM, Poirier MC, O'Neill JP, Finette BA, Bauer MJ, Walker VE. Genotoxicity of 3'-azido-3'-deoxythymidine in the human lymphoblastoid cell line, TK6: relationships between DNA incorporation, mutant frequency, and spectrum of deletion mutations in HPRT. Mutat Res 1999; 429:249-59. [PMID: 10526209 DOI: 10.1016/s0027-5107(99)00111-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [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: 11/28/2022]
Abstract
Perinatal treatment with 3'-azido-3'-deoxythymidine (AZT) has been found to reduce the rate of maternal-infant transmission of HIV; however, AZT is genotoxic in mammalian cells in vitro and induces tumors in the offspring of mice treated in utero. The purpose of the present study was to investigate the relationships between incorporation of AZT into DNA, and the frequency and spectrum of mutations at the HPRT locus of the human lymphoblastoid cell line, TK6, following in vitro exposures to AZT. Cells were cultured in medium containing 0 or 300 microM AZT for 1, 3, or 6 day(s) (n = 5/group). The effects of exposure duration on incorporation of AZT into DNA and HPRT mutant frequency were determined using an AZT radioimmunoassay and a cell cloning assay, respectively. AZT accumulated in DNA in a supralinear manner, approaching a plateau at 6 days of treatment (101.9 +/- 14.7 molecules AZT/10(6) nucleotides). After 3 days of AZT exposure, HPRT mutant frequency was significantly increased (1.8-fold, p = 0.016) compared to background (mutant frequency = 3.78 x 10(-6)). Multiplex PCR amplification of genomic DNA was used to determine the frequency of exon deletions in HPRT mutant clones from untreated cells versus AZT-treated cells. Molecular analyses of AZT-induced mutations revealed a significant difference in the frequency of total gene deletions (44/120 vs. 18/114 in controls, p = 0.004 by the Mann-Whitney U-statistic). In fact, the Chi-square test of homogeneity demonstrate that the differences between the control and AZT-treatment groups is attributed mainly to this increase in total gene deletion mutations (p = 0.00001). These data indicate that the primary mechanism of AZT mutagenicity in human TK6 cells is through the production of large deletions which occur as a result of AZT incorporation into DNA and subsequent chain termination. The data imply that perinatal chemoprophylaxis with AZT may put children of HIV-infected women at potential risk for genetic damage.
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Affiliation(s)
- H E Sussman
- Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
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19
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Meng Q, Henderson RF, Walker DM, Bauer MJ, Reilly AA, Walker VE. Mutagenicity of the racemic mixtures of butadiene monoepoxide and butadiene diepoxide at the Hprt locus of T-lymphocytes following inhalation exposures of female mice and rats. Mutat Res 1999; 429:127-40. [PMID: 10434028 DOI: 10.1016/s0027-5107(99)00105-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The purpose of this study was to determine if Hprt mutant frequency (Mf) data from rodents exposed directly to individual epoxy metabolites of 1,3-butadiene (BD) can be used to identify the relative significance of each intermediate in the mutagenicity of BD in mice vs. rats. To this end, the relative contributions of the racemic mixtures of BD monoepoxide (BDO) and BD diepoxide (BDO(2)) to BD-induced mutagenicity was investigated by exposing mice and rats to selected concentrations of BDO and BDO(2) (i.e., 2.5 and 4.0 ppm, respectively) and comparing the mutagenic potency of each intermediate to that of BD (at 62.5 ppm) when comparable blood levels of metabolites are achieved (in the mouse). Female B6C3F1 mice and F344 rats (4-5 weeks old) were exposed to rac-BDO (0, 2.5, or 25 ppm) or (+/-)-BDO(2) (0, 2, 4 ppm) by inhalation for 4 weeks (6 h/day, 5 days/week), and then groups of control and exposed animals (n=3-12/group) were necropsied at multiple time points post-exposure for measuring Hprt Mfs in splenic lymphocytes (via the T-cell cloning assay) and estimating mutagenic potencies (represented by the difference in the areas under the mutant T-cell 'manifestation' curves of treated vs. control animals). The resulting Mf data, along with the extant metabolism data, suggest that at lower BD exposures (</=62.5 ppm) (+/-)-BDO(2) is a major contributor to the mutagenicity of BD in mice, whereas other metabolites and stereochemical configurations are responsible for mutations in BD-exposed rats and for the incremental mutagenic effects at higher BD exposures in mice. These studies indicate that additional work is needed to determine more definitively the relative contributions of these and other metabolites and stereochemical forms to BD-induced mutagenicity. Also, the novel approach of measuring mutagenic potencies as the change in Hprt Mfs over time in T-cells of exposed vs. control animals, as used in this study, can be valuable for predicting the potential role of these intermediates in each species.
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Affiliation(s)
- Q Meng
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201-0509, USA
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20
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Meng Q, Henderson RF, Chen T, Heflich RH, Walker DM, Bauer MJ, Reilly AA, Walker VE. Mutagenicity of 1,3-butadiene at the Hprt locus of T-lymphocytes following inhalation exposures of female mice and rats. Mutat Res 1999; 429:107-25. [PMID: 10434027 DOI: 10.1016/s0027-5107(99)00104-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [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: 10/18/2022]
Abstract
The species specific response to 1,3-butadiene (BD), an important industrial chemical, was investigated by determining the influence of exposure duration and exposure concentration on the mutagenicity of BD in mice and rats and by defining the spectra of mutations in the Hprt gene T-cell mutants from control and BD-exposed mice. Female B6C3F1 mice and F344 rats (4-5 weeks old) were exposed by inhalation to 0, 20, 62.5, or 625 ppm of BD for up to 4 weeks (6 h/day, 5 days/week). Groups of control and exposed animals (n=4-12/group) were necropsied at multiple time points after exposure and the T-cell cloning assay was used to measure Hprt mutant frequencies in lymphocytes isolated from spleen. Mutant clones collected from control and BD-exposed mice were propagated and analyzed by RT-PCR to produce Hprt cDNA for sequencing. In animals necropsied 4 weeks after 2 or 4 weeks of BD exposure (0 or 625 ppm), the rate of accumulation of mutations was greater in mice than in rats. Supra-linear dose-response curves were observed in BD-exposed mice, indicating a higher efficiency of mutant induction at lower concentrations of BD. The mutagenic potency estimates (represented by the differences in the areas under the mutant T-cell 'manifestation' curves of treated vs. control animals) in mice were 11 and 61 following 4 weeks of exposures to 62.5 and 625 ppm of BD, respectively, while mutant frequencies (Mfs) in rats were significantly increased only at 625 ppm BD (mutagenic potency of 7). Molecular analysis of Hprt cDNA from expanded T-cell clones from control and BD-exposed mice demonstrated an increased frequency of mutants in exposed animals that likely contain large deletions in the Hprt gene (P=0.016). These data indicate that both exposure duration and exposure concentration are important in determining the magnitude of mutagenic response to BD, and that mutagenic and carcinogenic properties of BD in mice may be related more to the ability of its metabolites to cause chromosomal deletions than to produce point mutations.
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Affiliation(s)
- Q Meng
- Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
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Abstract
Phthalic acid esters (PAE) have been used as plasticizers in many products. Here we estimate the contaminating potential of PAE codisposed with domestic wastes. In order to determine the maximum threat to the environment, we analysed several fractions of different household wastes. A maximum of 2.6% of di-(2-ethylhexyl) phthalate (DEHP) was measured in 'compound materials'. More than 90% of all the PAE present in the refuse was due to DEHP. Assuming defined compositions of the refuse we calculated that approx. 1 kg of phthalate esters per ton of dry waste may be codisposed. The actual amount of PAE that could be eluted by the leachate was estimated using laboratory bioreactors which were filled with waste of exactly known composition. Only approx. 1 g of PAE per ton of dry waste was leached. However, the elution of hydrophobic DEHP by the leachate is dependent on the composition of the waste which gave rise to different concentrations of dissolved organic carbon. Because of the experimental setup the amounts of leached PAE represent minimum levels of possible environmental contamination. Hence, there will be a constant output of PAE from unlined municipal landfills for decades.
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Affiliation(s)
- M J Bauer
- Department of Hydrology, University of Bayreuth, Germany
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