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Chovelon B, Ranganathan V, Srinivasan S, McConnell EM, Faure P, Fiore E, Ravelet C, Peyrin E, DeRosa M. Noncompetitive Determination of Small Analytes by Sandwich-Type Lateral Flow Assay Based on an Aptamer Kissing Complex. Anal Chem 2024; 96:6875-6880. [PMID: 38651263 DOI: 10.1021/acs.analchem.3c05472] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Here, we present the proof-of-concept of a lateral flow assay (LFA) that is capable of detecting small-molecule targets in a noncompetitive manner by deploying a sandwich-type format based on the aptamer kissing complex (AKC) strategy. A fluorescently labeled hairpin aptamer served as the signaling agent, while a specific RNA hairpin grafted onto the strip served as the capture element. The hairpin aptamer switched from an unfolded to a folded form in the presence of the target, resulting in kissing interactions between the loops of the reporter and the capture agents. This design triggered a target-dependent fluorescent signal at the test line. The AKC-based LFA was developed for the detection of adenosine, achieving a detection limit in the micromolar range. The assay revealed the presence of the same analyte in urine. The method also proved effective with another small molecule (theophylline). We believe that the AKC-based LFA approach could overcome many of the shortcomings associated with conventional signal-off methods and competitive processes.
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Affiliation(s)
- Benoit Chovelon
- University Grenoble Alpes, DPM UMR 5063, CNRS, F-38041 Grenoble, France
- Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU-Biology and Pathology Institute, F-38041 Grenoble, France
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Velu Ranganathan
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Sathya Srinivasan
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Erin M McConnell
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Patrice Faure
- University Grenoble Alpes, DPM UMR 5063, CNRS, F-38041 Grenoble, France
- Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU-Biology and Pathology Institute, F-38041 Grenoble, France
| | - Emmanuelle Fiore
- University Grenoble Alpes, DPM UMR 5063, CNRS, F-38041 Grenoble, France
| | - Corinne Ravelet
- University Grenoble Alpes, DPM UMR 5063, CNRS, F-38041 Grenoble, France
| | - Eric Peyrin
- University Grenoble Alpes, DPM UMR 5063, CNRS, F-38041 Grenoble, France
| | - Maria DeRosa
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
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2
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Billet B, Chovelon B, McConnell EM, André D, Puillet-Anselme L, Fiore E, Faure P, Ravelet C, DeRosa MC, Peyrin E. Iodinated organic molecule as tag for inductively coupled Plasma-mass spectrometry aptamer assays. Talanta 2024; 267:125107. [PMID: 37672983 DOI: 10.1016/j.talanta.2023.125107] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 08/09/2023] [Accepted: 08/21/2023] [Indexed: 09/08/2023]
Abstract
Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) aptamer-based assays using metallic nanostructures or chelates as exogenous tags have gained growing attention in the last decade. We describe here a proof-of-concept study based on the exploitation of a simple organic molecule as a tag, i.e.l-thyroxine carrying four iodine atoms detectable by ICP-MS. A solid-phase assay involving the structure-switching format was deployed for the detection of the small molecule l-tyrosinamide as model target. The overall design involved (i) a reporter agent consisting of a DNA aptamer incorporating a single l-thyroxine label at its end and (ii) a capture agent, which is a partially complementary strand, immobilized on a microplate. Limit of detection in the nanomolar range was reported. The present labeling approach was further developed for the detection of a model protein (α-thrombin), using a sandwich mode, and proved effective in a biological matrix. We believe that the l-thyroxine tagging method could become a simple and robust alternative to commonly used labeling methods for ICP-MS aptamer-based assays.
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Affiliation(s)
- Blandine Billet
- University Grenoble Alpes, DPM UMR, 5063, F-38041, Grenoble, France; CNRS, DPM UMR, 5063, F-38041, Grenoble, France; Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU, Biology and Pathology Institute, F-38041, Grenoble, France
| | - Benoit Chovelon
- University Grenoble Alpes, DPM UMR, 5063, F-38041, Grenoble, France; CNRS, DPM UMR, 5063, F-38041, Grenoble, France; Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU, Biology and Pathology Institute, F-38041, Grenoble, France; Department of Chemistry, Carleton University, Ottawa, Canada.
| | | | - Dominique André
- Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU, Biology and Pathology Institute, F-38041, Grenoble, France
| | - Laurence Puillet-Anselme
- Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU, Biology and Pathology Institute, F-38041, Grenoble, France
| | - Emmanuelle Fiore
- University Grenoble Alpes, DPM UMR, 5063, F-38041, Grenoble, France; CNRS, DPM UMR, 5063, F-38041, Grenoble, France
| | - Patrice Faure
- University Grenoble Alpes, DPM UMR, 5063, F-38041, Grenoble, France; CNRS, DPM UMR, 5063, F-38041, Grenoble, France; Biochemistry, Toxicology and Pharmacology Department, Grenoble Site Nord CHU, Biology and Pathology Institute, F-38041, Grenoble, France
| | - Corinne Ravelet
- University Grenoble Alpes, DPM UMR, 5063, F-38041, Grenoble, France; CNRS, DPM UMR, 5063, F-38041, Grenoble, France
| | - Maria C DeRosa
- Department of Chemistry, Carleton University, Ottawa, Canada
| | - Eric Peyrin
- University Grenoble Alpes, DPM UMR, 5063, F-38041, Grenoble, France; CNRS, DPM UMR, 5063, F-38041, Grenoble, France.
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3
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Massey RS, McConnell EM, Chan D, Holahan MR, DeRosa MC, Prakash R. Non-invasive Monitoring of α-Synuclein in Saliva for Parkinson's Disease Using Organic Electrolyte-Gated FET Aptasensor. ACS Sens 2023; 8:3116-3126. [PMID: 37506391 DOI: 10.1021/acssensors.3c00757] [Citation(s) in RCA: 3] [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] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Parkinson's disease (PD) currently affects more than 1 million people in the US alone, with nearly 8.5 million suffering from the disease worldwide, as per the World Health Organization. However, there remains no fast, pain-free, and effective method of screening for the disease in the ageing population, which also happens to be the most susceptible to this neurodegenerative disease. αSynuclein (αSyn) is a promising PD biomarker, demonstrating clear delineations between levels of the αSyn monomer and the extent of αSyn aggregation in the saliva of PD patients and healthy controls. In this work, we have demonstrated a laboratory prototype of a soft fluidics integrated organic electrolyte-gated field-effect transistor (OEGFET) aptasensor platform capable of quantifying levels of αSyn aggregation in saliva. The aptasensor relies on a recently reported synthetic aptamer which selectively binds to αSyn monomer as the bio-recognition molecule within the integrated fluidic channel of the biosensor. The produced saliva sensor is label-free, fast, and reusable, demonstrating good selectivity only to the target molecule in its monomer form. The novelty of these devices is the fully isolated organic semiconductor, which extends the shelf life, and the novel fully integrated soft microfluidic channels, which simplify saliva loading and testing. The OEGFET aptasensor has a limit of detection of 10 fg/L for the αSyn monomer in spiked saliva supernatant solutions, with a linear range of 100 fg/L to 10 μg/L. The linear range covers the physiological range of the αSyn monomer in the saliva of PD patients. Our biosensors demonstrate a desirably low limit of detection, an extended linear range, and fully integrated microchannels for saliva sample handling, making them a promising platform for non-invasive point-of-care testing of PD.
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Affiliation(s)
- Roslyn S Massey
- Department of Electronics Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S5B6, Canada
| | - Erin M McConnell
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1T2S2, Canada
| | - Dennis Chan
- Dept of Neuroscience, Health Sciences Building, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1T2S2, Canada
| | - Matthew R Holahan
- Dept of Neuroscience, Health Sciences Building, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1T2S2, Canada
| | - Maria C DeRosa
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1T2S2, Canada
| | - Ravi Prakash
- Department of Electronics Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S5B6, Canada
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4
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Srinivasan S, Ranganathan V, McConnell EM, Murari BM, DeRosa MC. Aptamer-based colorimetric and lateral flow assay approaches for the detection of toxic metal ions, thallium(i) and lead(ii). RSC Adv 2023; 13:20040-20049. [PMID: 37409036 PMCID: PMC10318611 DOI: 10.1039/d3ra01658g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 03/13/2023] [Accepted: 06/14/2023] [Indexed: 07/07/2023] Open
Abstract
Thallium(i) and lead(ii) ions are heavy metals and extremely toxic. These metals are environmental pollutants, posing a severe risk to the environment and human health. In this study, two approaches were examined using aptamer and nanomaterial-based conjugates for thallium and lead detection. The first approach utilized an in-solution adsorption-desorption approach to develop colorimetric aptasensors for the detection of thallium(i) and lead(ii) using gold or silver nanoparticles. The second approach was the development of lateral flow assays, and their performance was tested with thallium (limit of detection is 7.4 μM) and lead ion (limit of detection is 6.6 nM) spiked into real samples. The approaches assessed are rapid, inexpensive, and time efficient with the potential to become the basis for future biosensor devices.
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Affiliation(s)
- Sathya Srinivasan
- Department of Chemistry, Carleton University 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada +1-613-520-2600 ext. 4388
- Department of Biotechnology, School of Bioscience and Technology VIT Vellore 632 104 TN India
| | - Velu Ranganathan
- Department of Chemistry, Carleton University 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada +1-613-520-2600 ext. 4388
| | - Erin M McConnell
- Department of Chemistry, Carleton University 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada +1-613-520-2600 ext. 4388
| | - Bhaskar Mohan Murari
- Department of Sensor and Biomedical Technology, School of Electronics Engineering VIT Vellore 632 104 TN India
| | - Maria C DeRosa
- Department of Chemistry, Carleton University 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada +1-613-520-2600 ext. 4388
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5
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Pandey R, Lu Y, McConnell EM, Osman E, Scott A, Gu J, Hoare T, Soleymani L, Li Y. Electrochemical DNAzyme-based biosensors for disease diagnosis. Biosens Bioelectron 2023; 224:114983. [PMID: 36640547 DOI: 10.1016/j.bios.2022.114983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 01/01/2023]
Abstract
DNAzyme-based electrochemical biosensors provide exceptional analytical sensitivity and high target recognition specificity for disease diagnosis. This review provides a critical perspective on the fundamental and applied impact of incorporating DNAzymes in the field of electrochemical biosensing. Specifically, we highlight recent advances in creating DNAzyme-based electrochemical biosensors for diagnosing infectious diseases, cancer and regulatory diseases. We also develop an understanding of challenges around translating the research in the field of DNAzyme-based electrochemical biosensors from labs to clinics, followed by a discussion on different strategies that can be applied to enhance the performance of the currently existing technologies to create truly point-of-care electrochemical DNAzyme biosensors.
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Affiliation(s)
- Richa Pandey
- Department of Engineering Physics, McMaster University, Hamilton, Ontario, L8S 4K1, Canada; Department of Biomedical Engineering, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.
| | - Yang Lu
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Erin M McConnell
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Enas Osman
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Alexander Scott
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Jimmy Gu
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Todd Hoare
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada; Department of Chemical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Leyla Soleymani
- Department of Engineering Physics, McMaster University, Hamilton, Ontario, L8S 4K1, Canada; School of Biomedical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada; Michael G. DeGroot Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, L8S 4K1, Canada.
| | - Yingfu Li
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada; Michael G. DeGroot Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, L8S 4K1, Canada.
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6
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Aartsma-Rus A, Garanto A, van Roon-Mom W, McConnell EM, Suslovitch V, Yan WX, Watts JK, Yu TW. Consensus Guidelines for the Design and In Vitro Preclinical Efficacy Testing N-of-1 Exon Skipping Antisense Oligonucleotides. Nucleic Acid Ther 2023; 33:17-25. [PMID: 36516128 PMCID: PMC9940807 DOI: 10.1089/nat.2022.0060] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Antisense oligonucleotides (ASOs) can modulate pre-mRNA splicing. This offers therapeutic opportunities for numerous genetic diseases, often in a mutation-specific and sometimes even individual-specific manner. Developing therapeutic ASOs for as few as even a single patient has been shown feasible with the development of Milasen for an individual with Batten disease. Efforts to develop individualized ASOs for patients with different genetic diseases are ongoing globally. The N = 1 Collaborative (N1C) is an umbrella organization dedicated to supporting the nascent field of individualized medicine. N1C recently organized a workshop to discuss and advance standards for the rigorous design and testing of splice-switching ASOs. In this study, we present guidelines resulting from that meeting and the key recommendations: (1) dissemination of standardized experimental designs, (2) use of standardized reference ASOs, and (3) a commitment to data sharing and exchange.
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Affiliation(s)
- Annemieke Aartsma-Rus
- Dutch Center for RNA Therapeutics, the Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.,N = 1 Collaborative
| | - Alejandro Garanto
- Dutch Center for RNA Therapeutics, the Netherlands.,Department of Pediatrics and Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Willeke van Roon-Mom
- Dutch Center for RNA Therapeutics, the Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Victoria Suslovitch
- N = 1 Collaborative.,Department of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | | | - Jonathan K Watts
- RNA Therapeutics Institute, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Timothy W Yu
- N = 1 Collaborative.,Department of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Division of Genetics and Genomics, Boston, Massachusetts, USA
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7
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Buijsen RAM, Lacroix A, Ochaba J, O'Reilly D, Abdullahu L, McConnell EM. 17th Annual Meeting of the Oligonucleotide Therapeutics Society: A Tribute to Bob Letsinger, Progress in N = 1 Treatments, and Successful First In-Humans CRISPR Trials. Nucleic Acid Ther 2022; 32:1-7. [PMID: 35073224 DOI: 10.1089/nat.2021.29004.ots] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ronald A M Buijsen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Joseph Ochaba
- Ionis Pharmaceuticals, Carlsbad, California, USA.,n-Lorem Foundation, Carlsbad, California, USA
| | - Daniel O'Reilly
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Leonora Abdullahu
- Department of Chemistry, McGill University, Montréal, Canada.,Genetic Medicine, Eli Lilly and Company, Indianapolis, Indiana, USA
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8
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Earnest KG, McConnell EM, Hassan EM, Wunderlich M, Hosseinpour B, Bono BS, Chee MJ, Mulloy JC, Willmore WG, DeRosa MC, Merino EJ. Development and characterization of a DNA aptamer for MLL-AF9 expressing acute myeloid leukemia cells using whole cell-SELEX. Sci Rep 2021; 11:19174. [PMID: 34580387 PMCID: PMC8476576 DOI: 10.1038/s41598-021-98676-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 08/30/2021] [Indexed: 02/07/2023] Open
Abstract
Current classes of cancer therapeutics have negative side effects stemming from off-target cytotoxicity. One way to avoid this would be to use a drug delivery system decorated with targeting moieties, such as an aptamer, if a targeted aptamer is available. In this study, aptamers were selected against acute myeloid leukemia (AML) cells expressing the MLL-AF9 oncogene through systematic evolution of ligands by exponential enrichment (SELEX). Twelve rounds of SELEX, including two counter selections against fibroblast cells, were completed. Aptamer pools were sequenced, and three candidate sequences were identified. These sequences consisted of two 23-base primer regions flanking a 30-base central domain. Binding studies were performed using flow cytometry, and the lead sequence had a binding constant of 37.5 + / - 2.5 nM to AML cells, while displaying no binding to fibroblast or umbilical cord blood cells at 200 nM. A truncation study of the lead sequence was done using nine shortened sequences, and showed the 5' primer was not important for binding. The lead sequence was tested against seven AML patient cultures, and five cultures showed binding at 200 nM. In summary, a DNA aptamer specific to AML cells was developed and characterized for future drug-aptamer conjugates.
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Affiliation(s)
- Kaylin G Earnest
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, USA
| | - Erin M McConnell
- Department of Chemistry, Carleton University, Ottawa, ON, Canada
| | - Eman M Hassan
- Department of Chemistry, Carleton University, Ottawa, ON, Canada
| | - Mark Wunderlich
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | | | - Bianca S Bono
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Melissa J Chee
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - James C Mulloy
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | | | - Maria C DeRosa
- Department of Chemistry, Carleton University, Ottawa, ON, Canada.
| | - Edward J Merino
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, USA.
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9
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He L, Tessier DR, Briggs K, Tsangaris M, Charron M, McConnell EM, Lomovtsev D, Tabard-Cossa V. Digital immunoassay for biomarker concentration quantification using solid-state nanopores. Nat Commun 2021; 12:5348. [PMID: 34504071 PMCID: PMC8429538 DOI: 10.1038/s41467-021-25566-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [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] [Received: 11/16/2020] [Accepted: 08/12/2021] [Indexed: 12/05/2022] Open
Abstract
Single-molecule counting is the most accurate and precise method for determining the concentration of a biomarker in solution and is leading to the emergence of digital diagnostic platforms enabling precision medicine. In principle, solid-state nanopores—fully electronic sensors with single-molecule sensitivity—are well suited to the task. Here we present a digital immunoassay scheme capable of reliably quantifying the concentration of a target protein in complex biofluids that overcomes specificity, sensitivity, and consistency challenges associated with the use of solid-state nanopores for protein sensing. This is achieved by employing easily-identifiable DNA nanostructures as proxies for the presence (“1”) or absence (“0”) of the target protein captured via a magnetic bead-based sandwich immunoassay. As a proof-of-concept, we demonstrate quantification of the concentration of thyroid-stimulating hormone from human serum samples down to the high femtomolar range. Further optimization to the method will push sensitivity and dynamic range, allowing for development of precision diagnostic tools compatible with point-of-care format. The concentration of a biomarker in solution can be determined by counting single molecules. Here the authors report a digital immunoassay scheme with solid-state nanopore readout to quantify a target protein and use this to measure thyroid-stimulating hormone from human serum.
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Affiliation(s)
- Liqun He
- Department of Physics, University of Ottawa, Ottawa, Canada
| | | | - Kyle Briggs
- Department of Physics, University of Ottawa, Ottawa, Canada
| | | | - Martin Charron
- Department of Physics, University of Ottawa, Ottawa, Canada
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10
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Abstract
This article provides a comprehensive review of biosensing with DNAzymes, providing an overview of different sensing applications while highlighting major progress and seminal contributions to the field of portable biosensor devices and point-of-care diagnostics. Specifically, the field of functional nucleic acids is introduced, with a specific focus on DNAzymes. The incorporation of DNAzymes into bioassays is then described, followed by a detailed overview of recent advances in the development of in vivo sensing platforms and portable sensors incorporating DNAzymes for molecular recognition. Finally, a critical perspective on the field, and a summary of where DNAzyme-based devices may make the biggest impact are provided.
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Affiliation(s)
- Erin M McConnell
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
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11
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Cozma I, McConnell EM, Brennan JD, Li Y. DNAzymes as key components of biosensing systems for the detection of biological targets. Biosens Bioelectron 2021; 177:112972. [DOI: 10.1016/j.bios.2021.112972] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 01/01/2021] [Accepted: 01/02/2021] [Indexed: 12/11/2022]
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12
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Koudrina A, McConnell EM, Zurakowski JA, Cron GO, Chen S, Tsai EC, DeRosa MC. Exploring the Unique Contrast Properties of Aptamer-Gadolinium Conjugates in Magnetic Resonance Imaging for Targeted Imaging of Thrombi. ACS Appl Mater Interfaces 2021; 13:9412-9424. [PMID: 33395250 DOI: 10.1021/acsami.0c16666] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Objective: An important clinical question in the determination of the extent of thrombosis-related vascular conditions is the identification of blood clot location. Fibrin is a major molecular constituent of blood clots and can, therefore, be utilized in molecular imaging. In this proof-of-concept study, we sought to prepare a fibrin-targeting magnetic resonance imaging contrast agent, using a Gd(III)-loaded fibrinogen aptamer (FA) chelate conjugate (Gd(III)-NOTA-FA) (NOTA = 1,4,7-triazacyclononane-1,4,7-triacetic acid), to endow the ability to specifically accumulate at the location of blood clots, thereby enhancing contrast capabilities. Methods: The binding affinity of FA for fibrin was confirmed by fluorescence microscopy and microscale thermophoresis. The preparation and effective loading of the chelate-aptamer conjugates were confirmed by mass spectrometry and a xylenol orange colorimetric test. Longitudinal and transverse relaxivities and the effects of target binding were assessed using T1- and T2-map sequences at 7 T. T1- and T2-weighted images were acquired after blood clots were treated with Gd(III)-NOTA-FA. Collagen was used as the protein control, while an unrelated aptamer sequence, FB139, was used as the aptamer control. Results: FA demonstrated a high affinity and selectivity toward the polymeric protein, with a Kd of 16.6 nM, confirming an avidity over fibrinogen. The longitudinal (r1) and transverse (r2) relaxivities of Gd(III)-NOTA-FA demonstrated that conjugation to the long aptamer strand shortened T1 relaxation times and increased T2 relaxation times (3.04 and 38.7 mM-1 s-1, respectively). These effects were amplified by binding to the fibrin target (1.73 and 46.5 mM-1 s-1, respectively). In vitro studies with thrombin-polymerized human blood (clots) in whole blood showed an unexpected enhancement of signal intensity (hyperintense) produced exclusively at the location of the clot during the T2-weighted scan, while the presence of fibrinogen within a whole blood pool resulted in T1 signal intensity enhancement throughout the pool. This is advantageous, as simply reversing the type of a scan from a typical T1-weighted to a T2-weighted would allow to selectively highlight the location of blood clots. Conclusions: Gd(III)-NOTA-FA can be used for molecular imaging of thrombi, through fibrin-targeted delivery of contrast to the location of blood clots in T2-weighted scans.
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Affiliation(s)
- Anna Koudrina
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - Erin M McConnell
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street W, Hamilton, ON L8S 4L8, Canada
| | - Joseph A Zurakowski
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - Greg O Cron
- The Ottawa Hospital, Ottawa, ON K1Y 4E9, Canada
- Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
- Department of Radiology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Suzan Chen
- The Ottawa Hospital, Ottawa, ON K1Y 4E9, Canada
- Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
| | - Eve C Tsai
- The Ottawa Hospital, Ottawa, ON K1Y 4E9, Canada
- Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
| | - Maria C DeRosa
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
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13
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Rothenbroker M, McConnell EM, Gu J, Urbanus ML, Samani SE, Ensminger AW, Filipe CDM, Li Y. Selection and Characterization of an RNA‐Cleaving DNAzyme Activated by
Legionella pneumophila. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202012444] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Meghan Rothenbroker
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | - Erin M. McConnell
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | - Jimmy Gu
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | | | | | | | | | - Yingfu Li
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
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14
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Rothenbroker M, McConnell EM, Gu J, Urbanus ML, Samani SE, Ensminger AW, Filipe CDM, Li Y. Selection and Characterization of an RNA‐Cleaving DNAzyme Activated by
Legionella pneumophila. Angew Chem Int Ed Engl 2021; 60:4782-4788. [DOI: 10.1002/anie.202012444] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 10/22/2020] [Indexed: 12/16/2022]
Affiliation(s)
- Meghan Rothenbroker
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | - Erin M. McConnell
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | - Jimmy Gu
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | | | | | | | | | - Yingfu Li
- Michael G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences McMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
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15
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Abstract
Due to their relative synthetic and chemical simplicity compared to antibodies, aptamers afford enhanced stability and functionality for the detection of environmental contaminants and for use in environmental monitoring. Furthermore, nucleic acid aptamers can be selected for toxic targets which may prove difficult for antibody development. Of particular relevance, aptamers have been selected and used to develop biosensors for environmental contaminants such as heavy metals, small-molecule agricultural toxins, and water-borne bacterial pathogens. This review will focus on recent aptamer-based developments for the detection of diverse environmental contaminants. Within this domain, aptamers have been combined with other technologies to develop biosensors with various signal outputs. The goal of much of this work is to develop cost-effective, user-friendly detection methods that can complement or replace traditional environmental monitoring strategies. This review will highlight recent examples in this area. Additionally, with innovative developments such as wearable devices, sentinel materials, and lab-on-a-chip designs, there exists significant potential for the development of multifunctional aptamer-based biosensors for environmental monitoring. Examples of these technologies will also be highlighted. Finally, a critical perspective on the field, and thoughts on future research directions will be offered.
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Affiliation(s)
| | | | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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16
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Manochehry S, Gu J, McConnell EM, Salena BJ, Li Y. In Vitro Selection of New DNA Aptamers for Human Vascular Endothelial Growth Factor 165. Chembiochem 2020; 21:2029-2036. [PMID: 32180322 DOI: 10.1002/cbic.202000024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/26/2020] [Indexed: 11/06/2022]
Abstract
Two DNA aptamers that bind the heparin-binding domain (HBD) of the human vascular endothelial growth factor 165 (VEGF-165) have been previously reported. Although VEGF-165 is a homodimeric protein and the two aptamers have different sequences and secondary structures, the aptamers appear to occupy the same binding site and cannot form a 2 : 1 aptamer/protein complex, thus making them unsuitable for creating a higher-affinity dimeric DNA aptamer. This has motivated us to conduct a new in vitro selection experiment to search for new VEGF-165-binding DNA aptamers with different properties. We undertook a multistream selection strategy in which the concentration of VEGF-165 was varied significantly. We carried out 11 rounds of selection, and next-generation sequencing was conducted for every round in each stream. From comprehensive sequence analysis, we identified four classes of DNA aptamers, of which two were reported before, but two are new DNA aptamers. One of the new aptamers exhibits a unique property that has never been observed before: it is capable of forming the 2 : 1 aptamer/protein complex with VEGF-165. This work has expanded the repertoire of VEGF-165-binding DNA aptamers and creates a possibility to engineer a higher affinity homodimeric aptamer for VEGF-165.
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Affiliation(s)
- Sepehr Manochehry
- M.G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 K1, Canada
| | - Jimmy Gu
- M.G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 K1, Canada
| | - Erin M McConnell
- M.G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 K1, Canada
| | - Bruno J Salena
- Department of Medicine DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 K1, Canada
| | - Yingfu Li
- M.G. DeGroote Institute for Infectious Disease Research Department of Biochemistry and Biomedical Sciences DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 K1, Canada
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17
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McConnell EM, Morrison D, Rey Rincon MA, Salena BJ, Li Y. Selection and applications of synthetic functional DNAs for bacterial detection. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2019.115785] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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18
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Abstract
This article provides an extensive review of paper-based sensors that utilize functional nucleic acids, particularly DNA aptamers and DNAzymes, as recognition elements.
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Affiliation(s)
- Rudi Liu
- Department of Biochemistry and Biomedical Sciences
- McMaster University
- Hamilton
- Canada
| | - Erin M. McConnell
- Department of Biochemistry and Biomedical Sciences
- McMaster University
- Hamilton
- Canada
| | - Jiuxing Li
- Department of Biochemistry and Biomedical Sciences
- McMaster University
- Hamilton
- Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences
- McMaster University
- Hamilton
- Canada
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19
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Samani SE, Chang D, McConnell EM, Rothenbroker M, Filipe CDM, Li Y. Highly Sensitive RNA-Cleaving DNAzyme Sensors from Surface-to-Surface Product Enrichment. Chembiochem 2019; 21:632-637. [PMID: 31544309 DOI: 10.1002/cbic.201900575] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Indexed: 12/13/2022]
Abstract
The engineering of easy-to-use biosensors with ultra-low detection sensitivity remains a major challenge. Herein, we report a simple approach for creating such sensors through the use of an RNA-cleaving DNAzyme (RcD) and a strategy designed to concentrate its cleavage product significantly. The assay uses micron-sized beads loaded with a target-responsive RcD and a paper strip containing a microzone covered with a DNA oligonucleotide capable of capturing the cleavage product of the RcD through Watson-Crick hybridization. Placing the beads and the paper strip in a target-containing test sample allows the bead-bound RcD molecules to undergo target-induced RNA cleavage, releasing a DNA fragment that is captured by the paper strip. This strategy, though simple, is very effective in achieving high levels of detection sensitivity, being able to enrich the concentration of the cleavage product by three orders of magnitude. It is also compatible with both fluorescence-based and colorimetric reporting mechanisms. This work provides a simple platform for developing ultrasensitive biosensors that take advantage of the widely available RcDs as molecular recognition elements.
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Affiliation(s)
- Sahar Esmaeili Samani
- Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Dingran Chang
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Erin M McConnell
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Meghan Rothenbroker
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Carlos D M Filipe
- Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
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20
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Manochehry S, McConnell EM, Li Y. Unraveling Determinants of Affinity Enhancement in Dimeric Aptamers for a Dimeric Protein. Sci Rep 2019; 9:17824. [PMID: 31780794 PMCID: PMC6883073 DOI: 10.1038/s41598-019-54005-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 09/20/2019] [Indexed: 11/09/2022] Open
Abstract
High-affinity aptamers can be derived de novo by using stringent conditions in SELEX (Systematic Evolution of Ligands by EXponential enrichment) experiments or can be engineered post SELEX via dimerization of selected aptamers. Using electrophoretic mobility shift assays, we studied a series of heterodimeric and homodimeric aptamers, constructed from two DNA aptamers with distinct primary sequences and secondary structures, previously isolated for VEGF-165, a homodimeric protein. We investigated four factors envisaged to impact the affinity of a dimeric aptamer to a dimeric protein: (1) length of the linker between two aptamer domains, (2) linking orientation, (3) binding-site compatibility of two component aptamers in a heterodimeric aptamer, and (4) steric acceptability of the two identical aptamers in a homodimeric aptamer. All heterodimeric aptamers for VEGF-165 were found to exhibit monomeric aptamer-like affinity and the lack of affinity enhancement was attributed to binding-site overlap by the constituent aptamers. The best homodimeric aptamer showed 2.8-fold better affinity than its monomeric unit (Kd = 13.6 ± 2.7 nM compared to 37.9 ± 14 nM), however the barrier to further affinity enhancement was ascribed to steric interference of the constituent aptamers. Our findings point to the need to consider the issues of binding-site compatibility and spatial requirement of aptamers for the development of dimeric aptamers capable of bivalent recognition. Thus, determinants highlighted herein should be assessed in future multimerization efforts.
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Affiliation(s)
- Sepehr Manochehry
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4K1, Canada
| | - Erin M McConnell
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4K1, Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4K1, Canada. .,Department of Chemistry and Chemical Biology, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4K1, Canada.
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21
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Affiliation(s)
- Erin M McConnell
- Department of Biochemistry and Biomedical Sciences , McMaster University , Hamilton , Ontario , Canada , L8S 4K1
| | - Ioana Cozma
- Department of Biochemistry and Biomedical Sciences , McMaster University , Hamilton , Ontario , Canada , L8S 4K1.,Department of Surgery, Division of General Surgery , McMaster University , Hamilton , Ontario , Canada , L8S 4K1
| | - Devon Morrison
- Department of Biochemistry and Biomedical Sciences , McMaster University , Hamilton , Ontario , Canada , L8S 4K1
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences , McMaster University , Hamilton , Ontario , Canada , L8S 4K1
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22
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McConnell EM, Ventura K, Dwyer Z, Hunt V, Koudrina A, Holahan MR, DeRosa MC. In Vivo Use of a Multi-DNA Aptamer-Based Payload/Targeting System To Study Dopamine Dysregulation in the Central Nervous System. ACS Chem Neurosci 2019; 10:371-383. [PMID: 30160936 DOI: 10.1021/acschemneuro.8b00292] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [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: 01/23/2023] Open
Abstract
The delivery of therapeutics across the blood-brain barrier remains a considerable challenge in investigating central nervous system related processes. In this work, a liposome vehicle was surface-modified with an aptamer that binds to the transferrin receptor and was loaded with two different dopamine-binding aptamer payloads. This system was effectively used to promote the delivery of the aptamer cargo from the peripheral injection site into the brain. The effect of these delivered aptamers on behavior was investigated in vivo in a locomotor task. The first dopamine binding aptamer assessed was a DNA aptamer, the binding of which had been previously validated through the aptamer-based biosensor development reported by several independent research groups. The second aptamer investigated was the result of a novel in vitro selection experiment described herein. Our data suggest that systemic administration of the modified liposomes led to delivery of the dopamine aptamers into the brain. Fluorescence microscopy revealed differential distribution of fluorescence based on the presence or absence of the transferrin receptor aptamer on the surface of fluorescently modified liposomes. In a behavioral experiment using cocaine administration to induce elevated concentrations of neural dopamine, systemic pretreatment with the dopamine aptamer-loaded liposomes reduced cocaine-induced hyperlocomotion. Multiple controls including a transferrin-negative liposome control and transferrin-positive liposomes loaded with either a nonbinding, base-substituted dopamine aptamer or a random oligonucleotide were investigated. None of these controls altered cocaine-induced hyperlocomotion. Chronic systemic administration of the modified liposomes produced no deleterious neurobehavioral or neural degenerative effects. Importantly, this work is one example of an application for this versatile multiaptamer payload/targeting system. Its general application is limited only by the availability of aptamers for specific neural targets.
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Affiliation(s)
- Erin M. McConnell
- Department of Chemistry, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Katelyn Ventura
- Department of Neuroscience, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Zach Dwyer
- Department of Neuroscience, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Vernon Hunt
- Department of Chemistry, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Anna Koudrina
- Department of Chemistry, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Matthew R. Holahan
- Department of Neuroscience, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Maria C. DeRosa
- Department of Chemistry, Carleton University, Ottawa, ON K1S 5B6, Canada
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23
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Abstract
Ingestion of water containing toxic contaminants above levels deemed safe for human consumption can occur unknowingly since numerous common contaminants in drinking water are colorless and odorless. Uranyl is particularly problematic as it has been found at dangerous levels in sources of drinking water. Detection of this heavy metal-ion species in drinking water currently requires sending a sample to a laboratory where trained personnel use equipment to perform the analysis and turn-around times can be long. A pH-responsive colorimetric biosensor was developed to enable detection of uranyl in water which coupled the uranyl-specific 39E DNAzyme as a recognition element, and an enzyme capable of producing a pH change as the reporter element. The rapid colorimetric assay presented herein can detect uranyl in lake and well water at concentrations relevant for environmental monitoring, as demonstrated by the detection of uranyl at levels below the limits set for drinking water by major regulatory agencies including the World Health Organization (30 μg/L). This simple and inexpensive DNAzyme-based assay enabled equipment-free visual detection of 15 μg/L uranyl, using both solution-based and paper-based pH-dependent visualization strategies.
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Affiliation(s)
- Sepehr Manochehry
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamilton, ON, Canada
| | - Erin M. McConnell
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamilton, ON, Canada
| | - Kha Q. Tram
- Department of Chemistry and Chemical Biology, McMaster UniversityHamilton, ON, Canada
| | - Joseph Macri
- Department of Pathology and Molecular Medicine, McMaster UniversityHamilton, ON, Canada
- Hamilton Regional Laboratory Medicine ProgramHamilton, ON, Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamilton, ON, Canada
- Department of Chemistry and Chemical Biology, McMaster UniversityHamilton, ON, Canada
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24
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Liu M, Yin Q, McConnell EM, Chang Y, Brennan JD, Li Y. Frontispiece: DNAzyme Feedback Amplification: Relaying Molecular Recognition to Exponential DNA Amplification. Chemistry 2018. [DOI: 10.1002/chem.201881861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Meng Liu
- School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education)Dalian University of Technology Dalian 116024 P. R. China
| | - Qingxin Yin
- School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education)Dalian University of Technology Dalian 116024 P. R. China
| | - Erin M. McConnell
- Department of Biochemistry and Biomedical Sciences and Chemistry & Chemical BiologyMcMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
| | - Yangyang Chang
- School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education)Dalian University of Technology Dalian 116024 P. R. China
| | - John D. Brennan
- Biointerfaces InstituteMcMaster University 1280 Main Street West Hamilton ON L8S 4L8 Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences and Chemistry & Chemical BiologyMcMaster University 1280 Main Street West Hamilton ON L8S 4K1 Canada
- Biointerfaces InstituteMcMaster University 1280 Main Street West Hamilton ON L8S 4L8 Canada
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25
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Liu M, Yin Q, McConnell EM, Chang Y, Brennan JD, Li Y. DNAzyme Feedback Amplification: Relaying Molecular Recognition to Exponential DNA Amplification. Chemistry 2018; 24:4473-4479. [PMID: 29240289 DOI: 10.1002/chem.201705338] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Indexed: 01/10/2023]
Abstract
Technologies capable of linking DNA amplification to molecular recognition are very desirable for ultrasensitive biosensing applications. We have developed a simple but powerful isothermal DNA amplification method, termed DNAzyme feedback amplification (DFA), that is capable of relaying molecular recognition to exponential DNA amplification. The method incorporates both an RNA-cleaving DNAzyme (RCD) and rolling circle amplification (RCA) carried out by a special DNA polymerase using a circular DNA template. DFA begins with a stimulus-dependent RCA reaction, producing tandemly linked RCDs in long-chain DNA products. These RCDs cleave an RNA-containing DNA sequence to form additional primers that hybridize to the circular DNA molecule, giving rise to DNA assemblies that act as the new inputs for RCA. The RCA reaction and the cleavage event keep on feeding each other autonomously, resulting in exponential growth of repetitive DNA sequences that can be easily detected. This method can be used for the detection of both nucleic acid based targets and non-nucleic acid analytes. In this article, we discuss the conceptual framework of the feedback amplification approach, the essential features of this method as well as remaining challenges and possible solutions.
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Affiliation(s)
- Meng Liu
- School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian University of Technology, Dalian, 116024, P. R. China
| | - Qingxin Yin
- School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian University of Technology, Dalian, 116024, P. R. China
| | - Erin M McConnell
- Department of Biochemistry and Biomedical Sciences and Chemistry & Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Yangyang Chang
- School of Environmental Science and Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian University of Technology, Dalian, 116024, P. R. China
| | - John D Brennan
- Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences and Chemistry & Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.,Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada
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26
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Ruscito A, McConnell EM, Koudrina A, Velu R, Mattice C, Hunt V, McKeague M, DeRosa MC. In Vitro Selection and Characterization of DNA Aptamers to a Small Molecule Target. ACTA ACUST UNITED AC 2017; 9:233-268. [PMID: 29241295 DOI: 10.1002/cpch.28] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aptamers, synthetic oligonucleotide-based molecular recognition probes, have found use in a wide array of biosensing technologies based on their tight and highly selective binding to a variety of molecular targets. However, the inherent challenges associated with the selection and characterization of aptamers for small molecule targets have resulted in their underrepresentation, despite the need for small molecule detection in fields such as medicine, the environment, and agriculture. This protocol describes the steps in the selection, sequencing, affinity characterization, and truncation of DNA aptamers that are specific for small molecule targets. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
| | - Erin M McConnell
- Chemistry Department, Carleton University, Ottawa, Ontario, Canada
| | - Anna Koudrina
- Chemistry Department, Carleton University, Ottawa, Ontario, Canada
| | - Ranganathan Velu
- Chemistry Department, Carleton University, Ottawa, Ontario, Canada
| | | | - Vernon Hunt
- Chemistry Department, Carleton University, Ottawa, Ontario, Canada
| | - Maureen McKeague
- Department of Health Sciences and Technology, ETH Zürich, Zurich, Switzerland
| | - Maria C DeRosa
- Chemistry Department, Carleton University, Ottawa, Ontario, Canada
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27
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McConnell EM, Bolzon R, Mezin P, Frahm G, Johnston M, DeRosa MC. pHAST (pH-Driven Aptamer Switch for Thrombin) Catch-and-Release of Target Protein. Bioconjug Chem 2016; 27:1493-9. [PMID: 27115292 DOI: 10.1021/acs.bioconjchem.6b00124] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A pH-driven DNA nanomachine based on the human α-thrombin binding aptamer was designed for the specific catch-and-release of human α-thrombin at neutral and acidic pH, respectively. In neutral conditions, the thrombin aptamer component of the nanomachine is exposed and exists in the G-quadruplex conformation required to bind to the target protein. At slightly acidic pH, the polyadenine tail of the nanomachine becomes partially protonated and A+(anti)•G(syn) mispairing results in a conformational change, causing the target protein to be released. Förster resonance energy transfer (FRET) was used to monitor conformational switching over multiple pH cycles. Electrophoretic mobility shift assay (EMSA) and fluorescence anisotropy were used to show pH dependent protein binding and release by the nanomachine. This approach could be applied generally to existing G-rich aptamers to develop novel biosensors, theranostics, and nanoswitches.
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Affiliation(s)
- E M McConnell
- Chemistry Department, Carleton University 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - R Bolzon
- Chemistry Department, Carleton University 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - P Mezin
- Chemistry Department, Carleton University 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - G Frahm
- Centre for Biologics Evaluation, Health Canada , 251 Sir Frederick Banting, Ottawa, Ontario K1A 0K9, Canada
| | - M Johnston
- Centre for Biologics Evaluation, Health Canada , 251 Sir Frederick Banting, Ottawa, Ontario K1A 0K9, Canada
| | - M C DeRosa
- Chemistry Department, Carleton University 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
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28
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McKeague M, McConnell EM, Cruz-Toledo J, Bernard ED, Pach A, Mastronardi E, Zhang X, Beking M, Francis T, Giamberardino A, Cabecinha A, Ruscito A, Aranda-Rodriguez R, Dumontier M, DeRosa MC. Analysis of In Vitro Aptamer Selection Parameters. J Mol Evol 2015; 81:150-61. [PMID: 26530075 DOI: 10.1007/s00239-015-9708-6] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 10/22/2015] [Indexed: 10/22/2022]
Abstract
Nucleic acid aptamers are novel molecular recognition tools that offer many advantages compared to their antibody and peptide-based counterparts. However, challenges associated with in vitro selection, characterization, and validation have limited their wide-spread use in the fields of diagnostics and therapeutics. Here, we extracted detailed information about aptamer selection experiments housed in the Aptamer Base, spanning over two decades, to perform the first parameter analysis of conditions used to identify and isolate aptamers de novo. We used information from 492 published SELEX experiments and studied the relationships between the nucleic acid library, target choice, selection methods, experimental conditions, and the affinity of the resulting aptamer candidates. Our findings highlight that the choice of target and selection template made the largest and most significant impact on the success of a de novo aptamer selection. Our results further emphasize the need for improved documentation and more thorough experimentation of SELEX criteria to determine their correlation with SELEX success.
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Affiliation(s)
- Maureen McKeague
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Erin M McConnell
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Jose Cruz-Toledo
- Biology Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Elyse D Bernard
- Environmental Health Science and Research Bureau, Health Canada, Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada
| | - Amanda Pach
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Emily Mastronardi
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Xueru Zhang
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Michael Beking
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Tariq Francis
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Amanda Giamberardino
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Ashley Cabecinha
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Annamaria Ruscito
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Rocio Aranda-Rodriguez
- Environmental Health Science and Research Bureau, Health Canada, Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada
| | - Michel Dumontier
- Biology Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada. .,Stanford Center for Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, CA, 94305, USA.
| | - Maria C DeRosa
- Chemistry Department, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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McKeague M, De Girolamo A, Valenzano S, Pascale M, Ruscito A, Velu R, Frost NR, Hill K, Smith M, McConnell EM, DeRosa MC. Comprehensive analytical comparison of strategies used for small molecule aptamer evaluation. Anal Chem 2015; 87:8608-12. [PMID: 26192270 DOI: 10.1021/acs.analchem.5b02102] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nucleic acid aptamers are versatile molecular recognition agents that bind to their targets with high selectivity and affinity. The past few years have seen a dramatic increase in aptamer development and interest for diagnostic and therapeutic applications. As the applications for aptamers expand, the need for a more standardized, stringent, and informative characterization and validation methodology increases. Here we performed a comprehensive analysis of a panel of conventional affinity binding assays using a suite of aptamers for the small molecule target ochratoxin A (OTA). Our results highlight inconsistency between conventional affinity assays and the need for multiple characterization strategies. To mitigate some of the challenges revealed in our head-to-head comparison of aptamer binding assays, we further developed and evaluated a set of novel strategies that facilitate efficient screening and characterization of aptamers in solution. Finally, we provide a workflow that permits rapid and robust screening, characterization, and functional verification of aptamers thus improving their development and integration into novel applications.
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Affiliation(s)
- Maureen McKeague
- Department of Bioengineering, Stanford University , 443 Via Ortega, Stanford, California 94305, United States
| | - Annalisa De Girolamo
- Institute of Sciences of Food Production, National Research Council of Italy , via G. Amendola 122/O, 70126 Bari, Italy
| | - Stefania Valenzano
- Institute of Sciences of Food Production, National Research Council of Italy , via G. Amendola 122/O, 70126 Bari, Italy
| | - Michelangelo Pascale
- Institute of Sciences of Food Production, National Research Council of Italy , via G. Amendola 122/O, 70126 Bari, Italy
| | - Annamaria Ruscito
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Ranganathan Velu
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Nadine R Frost
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Kayla Hill
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - McKenzie Smith
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Erin M McConnell
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Maria C DeRosa
- Chemistry Department, Carleton University , 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
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McConnell EM, Holahan MR, DeRosa MC. Aptamers as promising molecular recognition elements for diagnostics and therapeutics in the central nervous system. Nucleic Acid Ther 2015; 24:388-404. [PMID: 25296265 DOI: 10.1089/nat.2014.0492] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Oligonucleotide aptamers are short, synthetic, single-stranded DNA or RNA able to recognize and bind to a multitude of targets ranging from small molecules to cells. Aptamers have emerged as valuable tools for fundamental research, clinical diagnosis, and therapy. Due to their small size, strong target affinity, lack of immunogenicity, and ease of chemical modification, aptamers are an attractive alternative to other molecular recognition elements, such as antibodies. Although it is a challenging environment, the central nervous system and related molecular targets present an exciting potential area for aptamer research. Aptamers hold promise for targeted drug delivery, diagnostics, and therapeutics. Here we review recent advances in aptamer research for neurotransmitter and neurotoxin targets, demyelinating disease and spinal cord injury, cerebrovascular disorders, pathologies related to protein aggregation (Alzheimer's, Parkinson's, and prions), brain cancer (glioblastomas and gliomas), and regulation of receptor function. Challenges and limitations posed by the blood brain barrier are described. Future perspectives for the application of aptamers to the central nervous system are also discussed.
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Affiliation(s)
- Erin M McConnell
- 1 Department of Chemistry, Carleton University , Ottawa, Ontario, Canada
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McConnell EM, Holahan MR, Madularu D, Walsh R, DeRosa MC. 90 Intra-accumbens injection of a dopamine aptamer abates MK-801-induced cognitive dysfunction in a model of Schizophrenia. J Biomol Struct Dyn 2013. [DOI: 10.1080/07391102.2013.786524] [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: 10/26/2022]
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Ladd GW, Kochenderfer-Ladd B, Eggum ND, Kochel KP, McConnell EM. Characterizing and comparing the friendships of anxious-solitary and unsociable preadolescents. Child Dev 2011; 82:1434-53. [PMID: 21883155 DOI: 10.1111/j.1467-8624.2011.01632.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Friendships matter for withdrawn youth because the consequences of peer isolation are severe. From a normative sample of 2,437 fifth graders (1,245 females; M age = 10.25), a subset (n = 1,364; 638 female) was classified into 3 groups (anxious-solitary, unsociable, comparison) and followed across a school year. Findings indicated that it was more common for unsociable than anxious-solitary children to have friends, be stably friended, and participate in multiple friendships. For withdrawn as well as nonwithdrawn children, peer rejection predicted friendlessness, but this relation was strongest for anxious-solitary children. The friends of unsociable youth were more accepted by peers than those of anxious-solitary youth. The premise that friendship inhibits peer victimization was substantiated for withdrawn as well as nonwithdrawn youth.
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Affiliation(s)
- Gary W Ladd
- Department of Psychology, School of Social and Family Dynamics, Arizona State University, Tempe, AZ 85287-3701, USA.
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Holahan MR, Madularu D, McConnell EM, Walsh R, DeRosa MC. Intra-accumbens injection of a dopamine aptamer abates MK-801-induced cognitive dysfunction in a model of schizophrenia. PLoS One 2011; 6:e22239. [PMID: 21779401 PMCID: PMC3135623 DOI: 10.1371/journal.pone.0022239] [Citation(s) in RCA: 18] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 06/16/2011] [Indexed: 11/18/2022] Open
Abstract
Systemic administration of the noncompetitive NMDA-receptor antagonist, MK-801, has been proposed to model cognitive deficits similar to those seen in patients with schizophrenia. The present work investigated the ability of a dopamine-binding DNA aptamer to regulate these MK-801-induced cognitive deficits when injected into the nucleus accumbens. Rats were trained to bar press for chocolate pellet rewards then randomly assigned to receive an intra-accumbens injection of a DNA aptamer (200 nM; n = 7), tris buffer (n = 6) or a randomized DNA oligonucleotide (n = 7). Animals were then treated systemically with MK-801 (0.1 mg/kg) and tested for their ability to extinguish their bar pressing response. Two control groups were also included that did not receive MK-801. Data revealed that injection of Tris buffer or the random oligonucleotide sequence into the nucleus accumbens prior to treatment with MK-801 did not reduce the MK-801-induced extinction deficit. Animals continued to press at a high rate over the entire course of the extinction session. Injection of the dopamine aptamer reversed this MK-801-induced elevation in lever pressing to levels as seen in rats not treated with MK-801. Tests for activity showed that the aptamer did not impair locomotor activity. Results demonstrate the in vivo utility of DNA aptamers as tools to investigate neurobiological processes in preclinical animal models of mental health disease.
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Affiliation(s)
- Matthew R. Holahan
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
- * E-mail: (MRH); (MD)
| | - Dan Madularu
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Erin M. McConnell
- Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
| | - Ryan Walsh
- Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
| | - Maria C. DeRosa
- Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
- * E-mail: (MRH); (MD)
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Abstract
A case of panhypopituitarism with hypothyroid-induced deafness in a man improving with hormone replacement is reported. A review of the medical literature reveals conflicting evidence regarding the underlying mechanism and prognosis of the defect in this context, but the association with hypothyroidism is more than spurious. Sensorineuronal hearing loss was initially evident, resolving both subjectively and on formal audiological evaluation after administering thyroxine. Central pathology affecting the eighth cranial nerve, as opposed to a conductive or mixed component is the likely culprit.
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Affiliation(s)
- D M Comer
- Craigavon Area Hospital Group Trust, 68 Lurgan Road, Craigavon, Northern Ireland, UK
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Mullan K, Sanabria C, Abram WP, McConnell EM, Courtney HC, Hunter SJ, McCance DR, Leslie H, Sheridan B, Atkinson AB. Long term effect of external pituitary irradiation on IGF1 levels in patients with acromegaly free of adjunctive treatment. Eur J Endocrinol 2009; 161:547-51. [PMID: 19661126 DOI: 10.1530/eje-09-0506] [Citation(s) in RCA: 14] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE It is established that external pituitary irradiation (EPI) effectively reduces serum GH levels in acromegaly. However, its effect in normalising serum IGF1 has been disputed. We looked at the number of our patients who achieved persistently normal IGF1 levels whilst free of adjunctive treatment for at least 1 year after EPI. PATIENTS AND DESIGN We identified 63 acromegalic patients between 1964 and 2004 who received EPI. Six were excluded: three had surgery after EPI, two had no medical records available, and one had a pituitary Yttrium implant. MEASUREMENTS Patients received 4500-5000 cGy in fractionated doses. IGF1 levels were correlated with their respective age-related reference ranges. RESULTS After EPI, the number of patients with normal IGF1 and free of adjunctive medical treatment for at least 1 year were four patients by 3 years, nine patients by 5 years and seventeen by 10 years, with the current number of 25/57 (44%). Concordance between IGF1 levels and random GH dropped from 90% at the time of EPI to 65% at 3 years, 66% at 5 years and 71% at 10 years. CONCLUSIONS We have demonstrated that, with time, EPI achieves a normal IGF1 in significant numbers of patients with acromegaly, thus obviating the need for life-long expensive medical therapy. For each patient this benefit has to be weighed against the possibility of new hypopituitarism as a result of the treatment. Any decision to use EPI is easier in the context of pre-existent hypopituitarism.
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Affiliation(s)
- K Mullan
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Belfast BT12 6BA, UK
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Lindsay JR, McConnell EM, Hunter SJ, McCance DR, Sheridan B, Atkinson AB. Poor responses to a test dose of subcutaneous octreotide predict the need for adjuvant therapy to achieve 'safe' growth hormone levels. Pituitary 2004; 7:139-144. [PMID: 16328564 DOI: 10.1007/s11102-005-1756-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Somatostatin analogues are an established treatment in acromegaly. This study was designed to evaluate whether the acute serum growth hormone (GH) response to a test dose of octreotide in acromegaly predicts longer-term response to the drug at 3 years. DESIGN AND METHODS In 23 patients, GH responses across 8 h to a subcutaneous test dose (50 microg) of octreotide were compared with GH levels after 3 years of therapy. The majority had pituitary surgery as primary therapy and at 3 years were receiving at least 600 microg octreotide daily subcutaneously or 20 mg LAR monthly intramuscularly. RESULTS Seven had a test day GH Nadir of 5 mU/l or less of whom 4 achieved GH < 5 mU/l at 3 years. Sixteen had a test day nadir GH of 10 mU/l or less and of these 8 achieved GH < 5 mU/l at 3 years. Seven of the 23 had a GH Nadir >10 mU/l and of these 3 had achieved GH <5 mU/l at 3 years. However all of these 3 had received external pituitary irradiation within 4 years of the 3 year assessment, as compared with 3 of the <5 mU/l nadir group and 5 of the <10 mU/l nadir group. CONCLUSIONS In patients on optimal long-term doses of octreotide for acromegaly, absence of a nadir GH <10 mU/l in the 8 h after a test dose was associated with failure to achieve GH levels associated with a normal life expectancy (5 mU/l or less) unless adjunctive external pituitary irradiation was given. As well as testing tolerability a test dose of octreotide may help in determining which patients should be offered early external pituitary irradiation or therapy with a GH receptor antagonist if surgery has failed to achieve 'safe' GH levels.
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Affiliation(s)
- J R Lindsay
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK
| | - E M McConnell
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK
| | - S J Hunter
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK
| | - D R McCance
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK
| | - B Sheridan
- Regional Endocrine Laboratory, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK
| | - A B Atkinson
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK.
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, BT12 6BA, UK.
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McConnell EM, Bell PM, Ennis C, Hadden DR, McCance DR, Sheridan B, Atkinson AB. Effects of low-dose oral hydrocortisone replacement versus short-term reproduction of physiological serum cortisol concentrations on insulin action in adult-onset hypopituitarism. Clin Endocrinol (Oxf) 2002; 56:195-201. [PMID: 11874410 DOI: 10.1046/j.0300-0664.2001.01447.x] [Citation(s) in RCA: 21] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Hypercortisolism is associated with impaired glucose tolerance and insulin resistance. For many years hydrocortisone 30 mg was the standard total daily replacement dose in adult hypopituitarism. The use of this conventional dose has now been shown to result in mild biochemical hypercortisolism and might contribute to the increased cardiovascular risk reported in hypopituitarism. The use of lower doses of hydrocortisone replacement therapy might prevent some of the adverse metabolic effects seen with conventional doses. PATIENTS In a randomized crossover study we assessed peripheral and hepatic insulin action in 15 ACTH-deficient patients with normal glucose tolerance on two occasions while receiving either a low-dose oral hydrocortisone replacement (LOR) therapy (15 mg at 0800, 5 mg at 1700) or a physiological hydrocortisone infusion (PHI), which achieved physiological serum cortisol concentrations. RESULTS Exogenous glucose infusion rates required to maintain euglycaemia were similar for the LOR and the PHI protocols (26.2 +/- 0.4 vs. 23.8 +/- 0.6 micromol/kg/min, respectively). Endogenous glucose production was also similar (12.0 +/- 2.5 vs. 11.6 +/- 2.4 micromol/kg/min, respectively) and in the post-absorptive state suppressed to a similar extent following insulin (4.5 +/- 2.0 vs. 5.1 +/- 3.1 micromol/kg/min). CONCLUSION Hydrocortisone replacement therapy at a dose of 15 mg with breakfast, 5 mg with evening meal does not increase peripheral or hepatic insulin resistance when compared to a hydrocortisone infusion designed to simulate physiological serum cortisol concentrations.
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Affiliation(s)
- E M McConnell
- Sir George E. Clark Metabolic Unit and Regional Endocrine Laboratory, Royal Victoria Hospital, Belfast, UK
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McConnell EM, Atkinson AB, Ennis C, Hadden DR, McCance DR, Sheridan B, Bell PM. The effects on insulin action in adult hypopituitarism of recombinant human GH therapy individually titrated for six months. J Clin Endocrinol Metab 2001; 86:5342-7. [PMID: 11701703 DOI: 10.1210/jcem.86.11.8044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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: 11/19/2022]
Abstract
There is controversy about the effect of replacement GH on insulin action in adult hypopituitary patients. GH replacement calculated from weight leads to unacceptable side effects in some patients. Recent studies suggest it should be individually titrated in adults using serum IGF-I levels. We have assessed the effect of titrated GH replacement on peripheral and hepatic insulin action in 13 adult-onset hypopituitary patients (8 males and 5 females; ages 47 +/- 10 yr, mean duration of hypopituitarism 6 yr) with confirmed GH deficiency (GHD; maximum GH <5 mU/liter during insulin induced hypoglycemia), ACTH deficiency, and normal glucose tolerance. All patients were on stable hydrocortisone replacement (15 mg with breakfast, 5 mg with evening meal) for at least 2 months before the trial. Insulin action was assessed by the euglycemic hyperinsulinemic glucose clamp technique (1 mU/kg x min) before and after 6 months of GH therapy. GH was started at 0.8 IU sc daily and titrated monthly until the serum IGF-I increased to within 1-2 SD of the mean of normal age-matched controls. Body mass index did not change significantly during the 6 months of GH therapy. Fasting plasma glucose and HbA1c increased significantly after 6 months (5.2 +/- 0.0 vs. 5.5 +/- 0.0 mmol/liter, P < 0.0001, and 4.5 +/- 0.1 vs. 4.7 +/- 0.1%, P < 0.0005, respectively). There was no increase in fasting serum insulin (51.6 +/- 10.2 vs. 60.0 +/- 10.2 pmol/liter, P = 0.12). Exogenous glucose infusion rates required to maintain euglycemia were similar after GH (23.0 +/- 0.4 vs. 21.1 +/- 0.3 micromol/kg x min, P = 0.6). Endogenous glucose production in the fasting state was also unchanged following GH (11.8 +/- 0.7 vs.12.3 +/- 0.9 micromol/kg x min, P = 0.5) and suppressed to a similar extent following insulin (4.4 +/- 0.8 vs. 5.5 +/- 0.8 micromol/kg x min, P = 0.3). In summary, GH therapy for 6 months, with serum IGF-I maintained in the upper physiological range, increased fasting plasma glucose and HbA1c. There was no effect on peripheral or hepatic insulin sensitivity. Patients receiving GH therapy require long-term monitoring of glucose tolerance.
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Affiliation(s)
- E M McConnell
- Sir George E. Clark Metabolic Unit, Royal Victoria Hospital, Belfast, BT12 6BA, Northern Ireland, United Kingdom
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McConnell EM, Bell PM, Hadden DR, McCance DR, Sheridan B, Atkinson AB. Prevalence of diabetes and impaired glucose tolerance in adult hypopituitarism on low dose oral hydrocortisone replacement therapy. Clin Endocrinol (Oxf) 2001; 54:593-9. [PMID: 11380489 DOI: 10.1046/j.1365-2265.2001.01269.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The conventional dosage of hydrocortisone, used for many years in the management of hypopituitarism (30 mg per day), has now been shown to be more than is physiologically necessary. On this conventional corticosteroid therapy studies have demonstrated an increased prevalence of diabetes and impaired glucose tolerance, which may contribute to the increased vascular morbidity and mortality reported in the condition. In these studies no information is available on oral glucose tolerance test (OGTT) timing in relation to administration of oral steroid and variable hydrocortisone doses were employed. PATIENTS In order to assess glucose tolerance in patients treated with lower, more physiological doses, we performed a 75-g OGTT at least 1 month after hydrocortisone therapy was adjusted to 15 mg at 0800 h and 5 mg at 1700 h in 45 adult onset hypopituitary patients (30 M, 15 F). Mean (+/- SD) duration of hypopituitarism was 12 +/- 10 years, mean age 52 +/- 14 years and BMI 29.3 +/- 5.1 kg/m2. All were on hydrocortisone, 43 on thyroxine, 31 on sex steroids, 9 on desmopressin and 33 had documented growth hormone deficiency. Hydrocortisone 15 mg was taken at 0800 and the OGTT commenced at 0900. RESULTS Using standard WHO criteria 36 patients (80%) had normal glucose tolerance, 1 (2%) had newly diagnosed diabetes and 8 (18%) had impaired glucose tolerance. Using the recently announced American Diabetes Association criteria for diagnosis 96% had normal glucose tolerance, 2% had diabetes and 2% impaired fasting glucose. CONCLUSION The markedly reduced prevalence of diabetes and impaired glucose tolerance on lower hydrocortisone replacement doses in our series of patients with hypopituitarism, not previously known to be diabetic, is of great interest. This lower prevalence may eventually result in reduced vascular complication rates.
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Affiliation(s)
- E M McConnell
- Metabolic Unit, Royal Victoria Hospital, Grosvenor Road, Belfast, BT12 6BA, Northern Ireland, UK
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Abstract
The transition from childhood through adolescence to adulthood is a difficult stage, particularly for patients with type 1 diabetes. The yearning for autonomy and independence, as well as the hormonal changes around the time of puberty, can manifest in poor glycaemic control. The focus on diet and weight increases the prevalence of eating disorders, compounding the difficulties in supervising diabetes patients. This can be exacerbated by the realisation that hyperglycaemia induces weight loss and the use of this knowledge to further manipulate diabetes control to gain a desired body image. The management of adolescents with type 1 diabetes is therefore challenging and requires close collaboration between psychological medicine and diabetes teams. This review describes the difficulties frequently encountered, with a description of four cases illustrating these points. Case 1 demonstrates the problem of needle phobia in a newly diagnosed patient with type 1 diabetes leading to persistent hyperglycaemia, the recognition of weight loss associated with this and the development of bulimia. The patient's overall management was further complicated by risk-taking behaviour. By the age of 24 years, she has developed diabetic retinopathy and autonomic neuropathy and continues to partake in risk-taking behaviour. Case 2 illustrates how the lack of parental support shortly after the development of type 1 diabetes led to poor glycaemic control and how teenagers often omit insulin to accommodate lifestyle and risk-taking behaviour. Case 3 further exemplifies the difficulty in managing patients with needle phobia and the fear of hypoglycaemia. Case 4 adds further weight to the need for parental support and the impact of deleterious life events on glycaemic control by manipulation of insulin dosage.
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Affiliation(s)
- E M McConnell
- Diabetes Unit, Ulster Hospital, 700 Upper Newtownards Road, Dundonald, Belfast, Northern Ireland BT16 1RH, UK
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McConnell EM, Harper R, Campbell M, Nelson JK. The 36th Annual Meeting of the European Association for the Study of Diabetes (EASD), Jerusalem, Israel, 17-21 September 2000. Diabetes Metab Res Rev 2001; 17:75-82. [PMID: 11241894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Affiliation(s)
- E M McConnell
- Diabetes Unit, Ulster Hospital, Dundonald, Belfast, Northern Ireland
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Abstract
Twenty-four cases with a malignant change involving one of the elements of an ovarian dermoid cyst are reported. The patients were older than those with benign ovarian dermoid cysts. Squamous carcinoma was most frequent with adenocarcinoma, undifferentiated carcinoma and a fibrosarcoma also occurring. Survival time after diagnosis was less than 1 year in 75% of the cases.
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Abstract
The histopathology of the head of the epididymis in cases of azoospermia associated with normal testicular function is described. In 2 specimens congenital absence of the vas deferens was associated with stuffing of all of the tubules with normal spermatozoa but no other abnormality. In 30 specimens from cases with idiopathic epididymal obstruction there were abnormalities in the vasa efferentia. These included both extreme narrowing of the lumen due to thickening of the wall by fibrosis and also distension of the lumen by sperm and degenerate debris. Small sperm granulomata were present in the tubular wall in 10 specimens and foreign body granulomata were present in 20 specimens. It is suggested that either persistent low grade infection, congenital abnormality or acute obstruction due to ischaemic or traumatic damage may be the initial lesion. If the infection or the obstruction is not speedily resolved, the condition may become self-perpetuating.
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Mitchell JA, McConnell EM. Safety: keeping eyes protected. Occup Health (Lond) 1979; 31:463-5. [PMID: 259955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Freedman LS, Edwards DN, McConnell EM, Downham DY. Histological grade and other prognostic factors in relation to survival of patients with breast cancer. Br J Cancer 1979; 40:44-55. [PMID: 454563 PMCID: PMC2009958 DOI: 10.1038/bjc.1979.139] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Records of 3085 patients registered with breast cancer at the Mersey Regional Cancer Registry have been analysed to evaluate the relative importance of possible prognostic factors. In a subgroup of 1759 patients, clinical stage and histological grade are shown to be strongly related to survival after treatment. In addition histological grade is related to the distribution of times to death after treatment. The results of this and 3 other studies have implications for the design and analysis of clinical trials in the primary treatment of breast cancer.
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Abstract
Abstract
Ninety-six cases of squamous carcinoma of the anal canal are described; 55 had arisen within the canal and 41 from the margin. The methods of treatment included abdominoperineal resection, local resection, and radiotherapy. The uncorrected 5-year survival time was 42 per cent; the prognosis was better if the tumour arose from the margin than within the canal.
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Abstract
Three cases of fungal endocarditis are described, each following a homograft valve replacement for aortic stenosis. The causative organism was C. albicans. The characteristic findings included soft, easily detached vegetations consisting of fungal colonies, aneurysms, embolization of large vessels, and lack of response to current therapeutic measures. The source of the infection is obscure.
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