1
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O’Flaherty R, Amez Martín M, Gardner RA, Jennings PM, Rudd PM, Spencer DIR, Falck D. Erythropoietin N-glycosylation of Therapeutic Formulations Quantified and Characterized: An Interlab Comparability Study of High-Throughput Methods. Biomolecules 2024; 14:125. [PMID: 38254725 PMCID: PMC10813422 DOI: 10.3390/biom14010125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/05/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
Recombinant human erythropoietin (EPO) is a biopharmaceutical frequently used in the treatment of anemia. It is a heavily glycosylated protein with a diverse and complex glycome. EPO N-glycosylation influences important pharmacological parameters, prominently serum half-life. Therefore, EPO N-glycosylation analysis is of the utmost importance in terms of controlling critical quality attributes. In this work, we performed an interlaboratory study of glycoanalytical techniques for profiling and in-depth characterization, namely (1) hydrophilic interaction liquid chromatography with fluorescence detection after 2-aminobenzamide labeling (HILIC-FLD(2AB)) and optional weak anion exchange chromatography (WAX) fractionation and exoglycosidase digestion, (2) HILIC-FLD after procainamide labeling (PROC) optionally coupled to electrospray ionization-MS and (3) matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS). All techniques showed good precision and were able to differentiate the unique N-glycosylation profiles of the various EPO preparations. HILIC-FLD showed higher precision, while MALDI-TOF-MS covered the most analytes. However, HILIC-FLD differentiated isomeric N-glycans, i.e., N-acetyllactosamine repeats and O-acetylation regioisomers. For routine profiling, HILIC-FLD methods are more accessible and cover isomerism in major structures, while MALDI-MS covers more minor analytes with an attractively high throughput. For in-depth characterization, MALDI-MS and HILIC-FLD(2AB)/WAX give a similar amount of orthogonal information. HILIC-FLD(PROC)-MS is attractive for covering isomerism of major structures with a significantly less extensive workflow compared to HILIC-FLD(2AB)/WAX.
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Affiliation(s)
- Róisín O’Flaherty
- National Institute for Bioprocessing, Research and Training, Fosters Avenue, Blackrock, A94 X099 Dublin, Ireland (P.M.J.)
- Department of Chemistry, Maynooth University, W23 F2K8 Maynooth, Ireland
| | - Manuela Amez Martín
- Ludger Ltd., Culham Science Centre, Abingdon OX14 3EB, UK; (M.A.M.); (R.A.G.); (D.I.R.S.)
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Richard A. Gardner
- Ludger Ltd., Culham Science Centre, Abingdon OX14 3EB, UK; (M.A.M.); (R.A.G.); (D.I.R.S.)
| | - Patrick M. Jennings
- National Institute for Bioprocessing, Research and Training, Fosters Avenue, Blackrock, A94 X099 Dublin, Ireland (P.M.J.)
| | - Pauline M. Rudd
- National Institute for Bioprocessing, Research and Training, Fosters Avenue, Blackrock, A94 X099 Dublin, Ireland (P.M.J.)
| | - Daniel I. R. Spencer
- Ludger Ltd., Culham Science Centre, Abingdon OX14 3EB, UK; (M.A.M.); (R.A.G.); (D.I.R.S.)
| | - David Falck
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
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2
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Cheeseman J, Badia C, Elgood-Hunt G, Gardner RA, Trinh DN, Monopoli MP, Kuhnle G, Spencer DIR, Osborn HMI. Elevated concentrations of Neu5Ac and Neu5,9Ac 2 in human plasma: potential biomarkers of cardiovascular disease. Glycoconj J 2023; 40:645-654. [PMID: 37991561 PMCID: PMC10788320 DOI: 10.1007/s10719-023-10138-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 11/23/2023]
Abstract
Cardiovascular disease (CVD) is a group of health conditions affecting the heart and vascular system with very high prevalence and mortality rates. The presence of CVD is characterised by high levels of inflammation which have previously been associated with increased plasma concentrations of N-acetyl neuraminic acid (Neu5Ac). While Neu5Ac has been studied in the context of CVD, Neu5,9Ac2 has not, despite being the second most abundant sialic acid in human plasma. A small-scale pilot study of thirty plasma samples from patients with diagnosed CVD, and thirty age and sex-matched healthy controls, was designed to gain insight into sialic acids as biomarkers for CVD and potential future areas of study. Each sample was assayed for Neu5Ac and Neu5,9Ac2 concentrations. Mean Neu5Ac and Neu5,9Ac2 concentrations were significantly elevated in patients with CVD compared to healthy controls (Neu5Ac: P < 0.001; Neu5,9Ac2: P < 0.04). Receiver operator curve (ROC) analysis indicated that both Neu5Ac and Neu5,9Ac2 have reasonable predictive power for the presence of CVD (Neu5Ac AUC: 0.86; Neu5,9Ac2 AUC: 0.71). However, while Neu5Ac had both good sensitivity (0.82) and specificity (0.81), Neu5,9Ac2 had equivalent specificity (0.81) but very poor sensitivity (0.44). A combination marker of Neu5Ac + Neu5,9Ac2 showed improvement over Neu5Ac alone in terms of predictive power (AUC: 0.93), sensitivity (0.87), and specificity (0.90). Comparison to a known inflammatory marker, high sensitivity c-reactive protein (hs-CRP: P-value: NS, ROC:0.50) was carried out, showing that both Neu5Ac and Neu5,9Ac2 outperformed this marker. Further to this, hs-CRP values were combined with the three different sialic acid markers to determine any effect on the AUC values. A slight improvement in AUC was noted for each of the combinations, with Neu5Ac + Neu5,9Ac2 + hs-CRP giving the best AUC of 0.97 overall. Thus, Neu5Ac would appear to offer good potential as a predictive marker for the presence of CVD, which the addition of Neu5,9Ac2 predictive power improves, with further improvement seen by the addition of hs-CRP.
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Affiliation(s)
- Jack Cheeseman
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
- Ludger Ltd, Culham Science Centre, Abingdon, OX14 3EB, UK
| | | | | | | | - Duong N Trinh
- Department of Chemistry, Royal College of Surgeons in Ireland (RCSI), Dublin 2, Dublin, D02 YN77, Ireland
- Department of Pharmaceutics and Pharmaceutical Technology, University of Medicine and Pharmacy, Vietnam National University, Hanoi, Vietnam
| | - Marco P Monopoli
- Department of Chemistry, Royal College of Surgeons in Ireland (RCSI), Dublin 2, Dublin, D02 YN77, Ireland
| | - Gunter Kuhnle
- Department of Food and Nutritional Sciences, University of Reading, Whiteknights, Reading, RG6 6AH, UK
| | | | - Helen M I Osborn
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
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3
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Shubhakar A, Jansen BC, Adams AT, Reiding KR, Ventham NT, Kalla R, Bergemalm D, Urbanowicz PA, Gardner RA, Wuhrer M, Halfvarson J, Satsangi J, Fernandes DL, Spencer DIR. Serum N-Glycomic Biomarkers Predict Treatment Escalation in Inflammatory Bowel Disease. J Crohns Colitis 2023:7000718. [PMID: 36694402 DOI: 10.1093/ecco-jcc/jjad012] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Indexed: 01/26/2023]
Abstract
Biomarkers to guide clinical decision-making at diagnosis of inflammatory bowel disease (IBD) are urgently needed. We investigated a composite serum N-glycomic biomarker to predict future disease course in a discovery cohort of 244 newly diagnosed IBD patients. Forty-seven individual glycan peaks were analysed using ultra-high performance liquid chromatography identifying 105 glycoforms from which 24 derived glycan traits were calculated. Multivariable logistic regression was performed to determine associations of derived glycan traits with disease. Cox proportional hazard models were used to predict treatment escalation from first-line treatment to biologics or surgery (hazard ratio (HR) 25.9, p=1.1×10-12; 95% confidence interval (CI), 8.52-78.78). Application to an independent replication cohort of 54 IBD patients yielded a HR of 5.1 (p=1.1×10-5; 95% CI, 2.54-10.1). These data demonstrate the prognostic capacity of serum N-glycan biomarkers and represent a step towards personalized medicine in IBD.
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Affiliation(s)
- Archana Shubhakar
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom.,Division of BioAnalytical Chemistry, VU University Amsterdam, Amsterdam, The Netherlands
| | - Bas C Jansen
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Alex T Adams
- Translational Gastroenterology Unit, University of Oxford, Oxford, United Kingdom
| | - Karli R Reiding
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands.,Division of Biomolecular Mass Spectrometry and Proteomics, Utrecht University, Utrecht, The Netherlands
| | - Nicholas T Ventham
- Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Rahul Kalla
- Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Daniel Bergemalm
- Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
| | | | - Richard A Gardner
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | | | - Manfred Wuhrer
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jonas Halfvarson
- Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
| | - Jack Satsangi
- Translational Gastroenterology Unit, University of Oxford, Oxford, United Kingdom
| | - Daryl L Fernandes
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Daniel I R Spencer
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
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McCraw AJ, Gardner RA, Davies AM, Spencer DIR, Grandits M, Wagner GK, McDonnell JM, Karagiannis SN, Chenoweth A, Crescioli S. Generation and Characterization of Native and Sialic Acid-Deficient IgE. Int J Mol Sci 2022; 23:13455. [PMID: 36362241 PMCID: PMC9657026 DOI: 10.3390/ijms232113455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/22/2022] [Accepted: 10/28/2022] [Indexed: 07/30/2023] Open
Abstract
Efficient characterization of IgE antibodies and their glycan structures is required for understanding their function in allergy and in the emerging AllergoOncology field for antibody immunotherapy. We report the generation, glyco-profiling and functional analysis of native and sialic acid-deficient glyco-engineered human IgE. The antibodies produced from human embryonic kidney cells were purified via a human IgE class-specific affinity matrix and structural integrity was confirmed by SDS-PAGE and size-exclusion chromatography (SEC). Purified IgEs specific for the tumor-associated antigens Chondroitin Sulfate Proteoglycan 4 (CSPG4-IgE) and Human Epidermal Growth Factor Receptor 2 (HER2-IgE) were devoid of by-products such as free light chains. Using neuraminidase-A, we generated sialic acid-deficient CSPG4-IgE as example glyco-engineered antibody. Comparative glycan analyses of native and glyco-engineered IgEs by Hydrophilic interaction liquid chromatography (HILIC)-high performance liquid chromatography (HPLC) indicated loss of sialic acid terminal residues and differential glycan profiles. Native and glyco-engineered CSPG4-IgEs recognized Fc receptors on the surface of human FcεRI-expressing rat basophilic leukemia RBL-SX38 cells, and of CD23/FcεRII-expressing human RPMI-8866 B-lymphocytes and bound to CSPG4-expressing A2058 human melanoma cells, confirming Fab-mediated recognition. When cross-linked on the cell surface, both IgEs triggered RBL-SX38 degranulation. We demonstrate efficient generation and functional competence of recombinant native and sialic acid-deficient IgEs.
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Affiliation(s)
- Alex J. McCraw
- St. John’s Institute of Dermatology, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
| | | | - Anna M. Davies
- Randall Centre for Cell and Molecular Biophysics, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
| | | | - Melanie Grandits
- St. John’s Institute of Dermatology, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
| | - Gerd K. Wagner
- St. John’s Institute of Dermatology, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
- Medical Biology Centre, School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - James M. McDonnell
- Randall Centre for Cell and Molecular Biophysics, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
| | - Sophia N. Karagiannis
- St. John’s Institute of Dermatology, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
- Breast Cancer Now Research Unit, School of Cancer & Pharmaceutical Sciences, Guy’s Cancer Centre, King’s College London, London SE1 9RT, UK
| | - Alicia Chenoweth
- St. John’s Institute of Dermatology, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
- Breast Cancer Now Research Unit, School of Cancer & Pharmaceutical Sciences, Guy’s Cancer Centre, King’s College London, London SE1 9RT, UK
| | - Silvia Crescioli
- St. John’s Institute of Dermatology, School of Basic & Medical Biosciences, King’s College London, London SE1 9RT, UK
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5
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Moran AB, Gardner RA, Wuhrer M, Lageveen-Kammeijer GSM, Spencer DIR. Sialic Acid Derivatization of Fluorescently Labeled N-Glycans Allows Linkage Differentiation by Reversed-Phase Liquid Chromatography-Fluorescence Detection-Mass Spectrometry. Anal Chem 2022; 94:6639-6648. [PMID: 35482581 PMCID: PMC9096788 DOI: 10.1021/acs.analchem.1c02610] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sialic acids have diverse biological roles, ranging from promoting up to preventing protein and cellular recognition in health and disease. The various functions of these monosaccharides are owed, in part, to linkage variants, and as a result, linkage-specific analysis of sialic acids is an important aspect of glycomic studies. This has been addressed by derivatization strategies using matrix-assisted laser desorption/ionization mass spectrometry (MS) or sialidase digestion arrays followed by liquid chromatography (LC)-MS. Despite this, these approaches are unable to simultaneously provide unambiguous assignment of sialic acid linkages and assess further isomeric glycan features within a single measurement. Thus, for the first time, we present the combination of procainamide fluorescent labeling with sialic acid linkage-specific derivatization via ethyl esterification and amidation for the analysis of released plasma N-glycans using reversed-phase (RP)LC-fluorescence detection (FD)-MS. As a result, α2,3- and α2,6-sialylated N-glycans, with the same mass prior to derivatization, are differentiated based on retention time, precursor mass, and fragmentation spectra, and additional sialylated isomers were also separated. Furthermore, improved glycan coverage and protocol precision were found via the novel application using a combined FD-MS quantification approach. Overall, this platform achieved unambiguous assignment of N-glycan sialic acid linkages within a single RPLC-FD-MS measurement, and by improving their retention on RPLC, this technique can be used for future investigations of released N-glycans as an additional or orthogonal method to current analytical approaches.
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Affiliation(s)
- Alan B Moran
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.,Ludger Ltd., Culham Science Centre, OX14 3EB Abingdon, United Kingdom
| | - Richard A Gardner
- Ludger Ltd., Culham Science Centre, OX14 3EB Abingdon, United Kingdom
| | - Manfred Wuhrer
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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6
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Trinh D, Gardner RA, Franciosi AN, McCarthy C, Keane MP, Soliman MG, O’Donnell JS, Meleady P, Spencer DIR, Monopoli MP. Nanoparticle Biomolecular Corona-Based Enrichment of Plasma Glycoproteins for N-Glycan Profiling and Application in Biomarker Discovery. ACS Nano 2022; 16:5463-5475. [PMID: 35341249 PMCID: PMC9047655 DOI: 10.1021/acsnano.1c09564] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 03/10/2022] [Indexed: 05/28/2023]
Abstract
Biomolecular corona formation has emerged as a recurring and important phenomenon in nanomedicine that has been investigated for potential applications in disease diagnosis. In this study, we have combined the "personalized protein corona" with the N-glycosylation profiling that has recently gained considerable interest in human plasma biomarker discovery as a powerful early warning diagnostic and patient stratification tool. We envisioned that the protein corona formation could be exploited as an enrichment step that is critically important in both proteomic and proteoglycomic workflows. By using silica nanoparticles, plasma fibrinogen was enriched to a level in which its proteomic and glycomic "fingerprints" could be traced with confidence. Despite being a more simplified glycan profile compared to full plasma, the corona glycan profile revealed a fibrinogen-derived glycan peak that was found to potentially distinguish lung cancer patients from controls in a pilot study.
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Affiliation(s)
- Duong
N. Trinh
- Department
of Chemistry, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin 2, Ireland
| | - Richard A. Gardner
- Ludger
Ltd., Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, United Kingdom
| | - Alessandro N. Franciosi
- UBC
Faculty of Medicine, Department of Respiratory Medicine, University of British Columbia, Vancouver, British Columbia V6Z 1Y6, Canada
| | - Cormac McCarthy
- Department
of Respiratory Medicine, St. Vincent’s
University Hospital, Dublin 4, Ireland
- School
of Medicine, University College Dublin, Dublin 4, Ireland
| | - Michael P. Keane
- Department
of Respiratory Medicine, St. Vincent’s
University Hospital, Dublin 4, Ireland
- School
of Medicine, University College Dublin, Dublin 4, Ireland
| | - Mahmoud G. Soliman
- Department
of Chemistry, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin 2, Ireland
- Physics Department,
Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo, Egypt
| | - James S. O’Donnell
- Irish
Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences,
Royal College of Surgeons in Ireland, University
of Medicine and Health Sciences, Dublin 2, Ireland
| | - Paula Meleady
- School
of
Biotechnology, Dublin City University, Dublin 9, Ireland
| | - Daniel I. R. Spencer
- Ludger
Ltd., Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, United Kingdom
| | - Marco P. Monopoli
- Department
of Chemistry, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin 2, Ireland
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Ward SE, O'Sullivan JM, Moran AB, Spencer DIR, Gardner RA, Sharma J, Fazavana J, Monopoli M, McKinnon TAJ, Chion A, Haberichter S, O'Donnell JS. Sialylation on O-linked glycans protects von Willebrand factor from macrophage galactose lectin-mediated clearance. Haematologica 2022; 107:668-679. [PMID: 33763999 PMCID: PMC8883566 DOI: 10.3324/haematol.2020.274720] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/12/2021] [Indexed: 11/17/2022] Open
Abstract
Terminal sialylation determines the plasma half-life of von Willebrand factor (VWF). A role for macrophage galactose lectin (MGL) in regulating hyposialylated VWF clearance has recently been proposed. In this study, we showed that MGL influences physiological plasma VWF clearance. MGL inhibition was associated with a significantly extended mean residence time and 3-fold increase in endogenous plasma VWF antigen levels (P<0.05). Using a series of VWF truncations, we further demonstrated that the A1 domain of VWF is predominantly responsible for enabling the MGL interaction. Binding of both full-length and VWF-A1-A2-A3 to MGL was significantly enhanced in the presence of ristocetin (P<0.05), suggesting that the MGL-binding site in A1 is not fully accessible in globular VWF. Additional studies using different VWF glycoforms demonstrated that VWF O-linked glycans, clustered at either end of the A1 domain, play a key role in protecting VWF against MGLmediated clearance. Reduced sialylation has been associated with pathological, increased clearance of VWF in patients with von Willebrand disease. Herein, we demonstrate that specific loss of α2-3 linked sialylation from O-glycans results in markedly increased MGL-binding in vitro, and markedly enhanced MGL-mediated clearance of VWF in vivo. Our data further show that the asialoglycoprotein receptor (ASGPR) does not have a significant role in mediating the increased clearance of VWF following loss of O-sialylation. Conversely however, we observed that loss of N-linked sialylation from VWF drives enhanced circulatory clearance predominantly via the ASGPR. Collectively, our data support the hypothesis that in addition to regulating physiological VWF clearance, the MGL receptor works in tandem with ASGPR to modulate enhanced clearance of aberrantly sialylated VWF in the pathogenesis of von Willebrand disease.
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Affiliation(s)
- Soracha E Ward
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
| | - Jamie M O'Sullivan
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
| | - Alan B Moran
- Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, United Kingdom; Leiden University Medical Centre, Centre for Proteomics and Metabolomics, 2300 RC Leiden
| | | | | | - Jyotika Sharma
- Department of Basic Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
| | - Judicael Fazavana
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
| | - Marco Monopoli
- Department of Chemistry, RCSI, 123 St. Stephen's Green, Dublin 2
| | - Thomas A J McKinnon
- Faculty of Medicine, Imperial College, Hammersmith Hospital, Ducane Road, London
| | - Alain Chion
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland
| | | | - James S O'Donnell
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland; National Children's Research Centre, Our Lady's Children's Hospital, Dublin, Ireland; National Coagulation Centre, St James's Hospital, Dublin.
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8
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Clemente E, Martinez-Moro M, Trinh DN, Soliman MG, Spencer DIR, Gardner RA, Kotsias M, Sánchez Iglesias A, Moya S, Monopoli MP. Probing the glycans accessibility in the nanoparticle biomolecular corona. J Colloid Interface Sci 2022; 613:563-574. [PMID: 35066229 DOI: 10.1016/j.jcis.2021.11.140] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 12/25/2022]
Abstract
HYPOTHESIS Following blood administration, the pristine surface of nanoparticles (NPs) associates with biomolecules from the surrounding environment forming the so-called "biomolecular corona". It is well accepted that the biomolecular corona dramatically affects the NP fate in the biological medium while the pristine surface is no longer available for binding. Recent studies have shown that the glycans associated with the proteins forming the corona have a role in the NP interaction with macrophages, but the glycan identities remain unknown. We aim here to identify the glycan composition of the biomolecular corona and to assess the role of these glycans in the interaction of the proteins from the corona with glycan binding biomolecules, such as lectins. EXPERIMENTS In this study, we have characterized the biomolecular corona of citrate stabilised gold NPs after exposure of the NPs to blood plasma at two different plasma concentrations, mimicking the in vitro and in vivo conditions. We have extensively characterized the biomolecular corona using HILIC chromatography and shotgun proteomics. Following this, a lectin binding assay was carried out using Dynamic Light Scattering (DLS) and Fluorescence Correlation Spectroscopy (FCS) to assess whether proteins with known affinity towards specific glycans would bind to the corona. FINDINGS Our findings highlighted that the protein corona composition is dependent on the exposing conditions. However, under both plasma concentrations, the biantennary sialylated glycans (A2G2S2) are enriched. DLS and FCS confirmed that the glycans are accessible for binding as the corona interacts with lectins with known affinity towards terminal sialic acids and the enzymatic removal of the glycans leads to a decrease in lectin affinity. This study shows for the first time that the glycans are present in the corona and that they could potentially be responsible for the modulation of NP biological processes as they can directly engage with glycan binding receptors that are highly expressed in an organism.
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Affiliation(s)
- Eva Clemente
- Chemistry Department, RCSI (Royal College of Surgeons in Ireland), 123 St Stephen Green, Dublin 2, Ireland
| | - Marta Martinez-Moro
- Centre for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo Miramon 182 C, 20014 Donostia-San Sebastian, Spain
| | - Duong N Trinh
- Chemistry Department, RCSI (Royal College of Surgeons in Ireland), 123 St Stephen Green, Dublin 2, Ireland
| | - Mahmoud G Soliman
- Chemistry Department, RCSI (Royal College of Surgeons in Ireland), 123 St Stephen Green, Dublin 2, Ireland; Physics Department, Faculty of Science, Al-Azhar University, Cairo, Egypt
| | - Daniel I R Spencer
- Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Richard A Gardner
- Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | | | - Ana Sánchez Iglesias
- Bionanoplasmonics Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo Miramon 182 C, 20014 Donostia-San Sebastian, Spain
| | - Sergio Moya
- Centre for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo Miramon 182 C, 20014 Donostia-San Sebastian, Spain.
| | - Marco P Monopoli
- Chemistry Department, RCSI (Royal College of Surgeons in Ireland), 123 St Stephen Green, Dublin 2, Ireland.
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9
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Cheeseman J, Badia C, Thomson RI, Kuhnle G, Gardner RA, Spencer DIR, Osborn H. Quantitative Standards of 4-O acetyl and 9-O acetyl N-acetyl Neuraminic Acid for the Analysis of Plasma and Serum. Chembiochem 2021; 23:e202100662. [PMID: 34874597 PMCID: PMC9303589 DOI: 10.1002/cbic.202100662] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/06/2021] [Indexed: 11/10/2022]
Abstract
N‐Acetylneuraminic acid (sialic acid, Neu5Ac) is one of a large, diverse family of nine‐carbon monosaccharides that play roles in many biological functions such as immune response. Neu5Ac has previously been identified as a potential biomarker for the presence and pathogenesis of cardiovascular disease (CVD), diabetes and cancer. More recent research has highlighted acetylated sialic acid derivatives, specifically Neu5,9Ac2, as biomarkers for oral and breast cancers, but advances in analysis have been hampered due to a lack of commercially available quantitative standards. We report here the synthesis of 9‐O‐ and 4‐O‐acetylated sialic acids (Neu5,9Ac2 and Neu4,5Ac2) with optimisation of previously reported synthetic routes. Neu5,9Ac2 was synthesised in 1 step in 68 % yield. Neu4,5Ac2 was synthesised in 4 steps in 39 % overall yield. Synthesis was followed by analysis of these standards via quantitative NMR (qNMR) spectroscopy. Their utilisation for the identification and quantification of specific acetylated sialic acid derivatives in biological samples is also demonstrated.
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Affiliation(s)
- Jack Cheeseman
- University of Reading - Whiteknights Campus: University of Reading, Pharmacy, UNITED KINGDOM
| | | | - Rebecca I Thomson
- University of Reading - Whiteknights Campus: University of Reading, Pharmacy, UNITED KINGDOM
| | | | | | | | - Helen Osborn
- The university of Reading, School of Chemistry, PO Box 224, Whiteknights, RG6 6AD, Reading, UNITED KINGDOM
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10
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Demus D, Urbanowicz PA, Gardner RA, Wu H, Juszczak A, Štambuk T, Medvidović EP, Owen KR, Gornik O, Juge N, Spencer DIR. Development of an exoglycosidase plate-based assay for detecting α1-3,4 fucosylation biomarker in individuals with HNF1A-MODY. Glycobiology 2021; 32:230-238. [PMID: 34939081 PMCID: PMC8966479 DOI: 10.1093/glycob/cwab107] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/28/2021] [Accepted: 10/06/2021] [Indexed: 11/23/2022] Open
Abstract
Maturity-onset diabetes of the young due to hepatocyte nuclear factor-1 alpha variants (HNF1A-MODY) causes monogenic diabetes. Individuals carrying damaging variants in HNF1A show decreased levels of α1-3,4 fucosylation, as demonstrated on antennary fucosylation of blood plasma N-glycans. The excellent diagnostic performance of this glycan biomarker in blood plasma N-glycans of individuals with HNF1A-MODY has been demonstrated using liquid chromatography methods. Here, we have developed a high-throughput exoglycosidase plate-based assay to measure α1-3,4 fucosylation levels in blood plasma samples. The assay has been optimized and its validity tested using 1000 clinical samples from a cohort of individuals with young-adult onset diabetes including cases with HNF1A-MODY. The α1-3,4 fucosylation levels in blood plasma showed a good differentiating power in identifying cases with damaging HNF1A variants, as demonstrated by receiver operating characteristic curve analysis with the AUC values of 0.87 and 0.95. This study supports future development of a simple diagnostic test to measure this glycan biomarker for application in a clinical setting.
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Affiliation(s)
- Daniel Demus
- Ludger Ltd., Culham Science Centre, Abingdon, OX14 3EB, United Kingdom.,Center for Proteomics and Metabolomics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | | | - Richard A Gardner
- Ludger Ltd., Culham Science Centre, Abingdon, OX14 3EB, United Kingdom
| | - Haiyang Wu
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, United Kingdom
| | - Agata Juszczak
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LE, United Kingdom
| | - Tamara Štambuk
- Genos Glycoscience Research Laboratory, Borongajska cesta 83h, 10000, Zagreb, Croatia.,Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, 10000 Zagreb, Croatia
| | - Edita Pape Medvidović
- Vuk Vrhovac University Clinic for Diabetes, Endocrinology and Metabolic Diseases, Merkur University Hospital, Zagreb University School of Medicine, Dugi dol 4A, 10000, Zagreb, Croatia
| | - Katharine R Owen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LE, United Kingdom.,NIHR Oxford Biomedical Research Centre, Oxford Hospitals NHS Foundation Trust, Oxford, OX3 9DU, United Kingdom
| | - Olga Gornik
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, 10000 Zagreb, Croatia
| | - Nathalie Juge
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, United Kingdom
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11
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Wiegmann V, Gardner RA, Spencer DIR, Baganz F. Equal mixing time enables scale-down and optimization of a CHO cell culture process using a shaken microbioreactor system. Biotechnol J 2021; 16:e2100360. [PMID: 34494367 DOI: 10.1002/biot.202100360] [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: 07/11/2021] [Revised: 09/03/2021] [Accepted: 09/03/2021] [Indexed: 11/07/2022]
Abstract
The advancement of microbioreactor technology in recent years has transformed early- and mid-stage process development. The monitoring and control capabilities of microbioreactors not only promote the quick accumulation of process knowledge but has also led to an increased scalability when compared to traditionally used systems such as shake flasks and microtitre plates. This study seeks to establish a framework for the micro-Matrix microbioreactor (Applikon-Biotechnology BV) as process development tool. Using the Dual Indicator System for Mixing Time, the system was initially characterized for mixing properties at varying operating conditions, which was found to yield mixing times between 0.9 and 41.8 s. A matched mixing time was proposed as scale-down criterion for an IgG4 producing GS-CHO fed-batch process between a 5 L stirred tank reactor (STR) and the micro-Matrix microbioreactor. Growth trends, maximum viable cell concentrations, final titre, and glycoprofiles were nearly identical at both scales. The scale-down model was then employed to optimize a bolus feeding regime using response surface methodology, which led to a 25.4% increase of the space-time yield and a 25% increase of the final titre. The optimized feeding strategy was validated at the small-scale and successfully scaled up to the 5 L STR. This work for the first time provides a framework of how the micro-Matrix microbioreactor can be implemented in a bioprocess development workflow and demonstrates scalability of growth and production kinetics as well as IgG4 glycosylation between the micro-Matrix and a benchtop-scale STR system.
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Affiliation(s)
- Vincent Wiegmann
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Gordon Street, London, WC1E 6BT, UK
| | | | | | - Frank Baganz
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Gordon Street, London, WC1E 6BT, UK
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12
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Cheeseman J, Kuhnle G, Stafford G, Gardner RA, Spencer DI, Osborn HM. Sialic acid as a potential biomarker for cardiovascular disease, diabetes and cancer. Biomark Med 2021; 15:911-928. [PMID: 34241547 DOI: 10.2217/bmm-2020-0776] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022] Open
Abstract
Cardiovascular disease (CVD), diabetes and cancer pose increasing global healthcare burdens. New biomarkers could enable earlier diagnosis of these diseases, leading to more effective treatment and lower associated healthcare burden. Elevated sialic acid concentration in plasma and serum has been positively correlated with the presence of CVDs, diabetes and the development of malignant tumors. This article reviews the use of total sialic acid (TSA), bound sialic acid (BSA) and free sialic acid (FSA) as potential biomarkers for these diseases and makes a comparison with existing markers. Elevated sialic acid has been shown to be indicative of the pathogenesis of CVD, diabetes and malignant tumors. While not a specific marker for one disease there is promise in utilizing sialic acid as a marker for monitoring disease progression and effectiveness of treatment programs.
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Affiliation(s)
- Jack Cheeseman
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - Gunter Kuhnle
- Department of Food & Nutritional Sciences, University of Reading, Whiteknights, Reading, RG6 6AH, UK
| | - Graham Stafford
- School of Clinical Dentistry, 19 Claremont Crescent, Sheffield, S10 2TA, UK
| | | | | | - Helen Mi Osborn
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
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13
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Kozak RP, Mondragon-Shem K, Williams C, Rose C, Perally S, Caljon G, Van Den Abbeele J, Wongtrakul-Kish K, Gardner RA, Spencer D, Lehane MJ, Acosta-Serrano Á. Tsetse salivary glycoproteins are modified with paucimannosidic N-glycans, are recognised by C-type lectins and bind to trypanosomes. PLoS Negl Trop Dis 2021; 15:e0009071. [PMID: 33529215 PMCID: PMC7880456 DOI: 10.1371/journal.pntd.0009071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/12/2021] [Accepted: 12/14/2020] [Indexed: 12/01/2022] Open
Abstract
African sleeping sickness is caused by Trypanosoma brucei, a parasite transmitted by the bite of a tsetse fly. Trypanosome infection induces a severe transcriptional downregulation of tsetse genes encoding for salivary proteins, which reduces its anti-hemostatic and anti-clotting properties. To better understand trypanosome transmission and the possible role of glycans in insect bloodfeeding, we characterized the N-glycome of tsetse saliva glycoproteins. Tsetse salivary N-glycans were enzymatically released, tagged with either 2-aminobenzamide (2-AB) or procainamide, and analyzed by HILIC-UHPLC-FLR coupled online with positive-ion ESI-LC-MS/MS. We found that the N-glycan profiles of T. brucei-infected and naïve tsetse salivary glycoproteins are almost identical, consisting mainly (>50%) of highly processed Man3GlcNAc2 in addition to several other paucimannose, high mannose, and few hybrid-type N-glycans. In overlay assays, these sugars were differentially recognized by the mannose receptor and DC-SIGN C-type lectins. We also show that salivary glycoproteins bind strongly to the surface of transmissible metacyclic trypanosomes. We suggest that although the repertoire of tsetse salivary N-glycans does not change during a trypanosome infection, the interactions with mannosylated glycoproteins may influence parasite transmission into the vertebrate host. In addition to helping the ingestion of a bloodmeal, the saliva of vector insects can modulate vertebrate immune responses. However, most research has focused on the salivary proteins, while the sugars (glycans) that modify them remain unexplored. Here we studied N-glycosylation, a common post-translational modification where sugar structures are attached to specific sites of a protein. Insect salivary N-glycans may affect how the saliva is recognized by the host, possibly playing a role during pathogen transmission. In this manuscript, we present the first detailed structural characterization of the salivary N-glycans in the tsetse fly Glossina morsitans, vector of African trypanosomiasis. We found that tsetse fly glycoproteins are mainly modified by simple N-glycans with short mannose modifications, which are recognised by mammalian C-type lectins (mannose receptor and DC-SIGN). Furthermore, we show that salivary glycoproteins bind to the surface of the trypanosomes that are transmitted to the vertebrate host; this opens up interesting questions as to the role of these glycoproteins in the successful establishment of infection by this parasite. Overall, our work represents a novel contribution towards the salivary N-glycome of an important insect vector, and towards the understanding of vector saliva and its complex effects in the vertebrate host.
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Affiliation(s)
| | - Karina Mondragon-Shem
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Christopher Williams
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Clair Rose
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Samirah Perally
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Guy Caljon
- Laboratory of Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Antwerp, Belgium
| | - Jan Van Den Abbeele
- Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp, Antwerp, Belgium
| | | | | | - Daniel Spencer
- Ludger Ltd., Culham Science Centre, Oxford, United Kingdom
| | - Michael J. Lehane
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Álvaro Acosta-Serrano
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- * E-mail:
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14
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Hendel JL, Gardner RA, Spencer DIR. Automation of Immunoglobulin Glycosylation Analysis. Exp Suppl 2021; 112:173-204. [PMID: 34687010 DOI: 10.1007/978-3-030-76912-3_5] [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] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The development of reliable, affordable, high-resolution glycomics technologies that can be used for many samples in a high-throughput manner are essential for both the optimization of glycosylation in the biopharmaceutical industry as well as for the advancement of clinical diagnostics based on glycosylation biomarkers. We will use this chapter to review the sample preparation processes that have been used on liquid-handling robots to obtain high-quality glycomics data for both biopharmaceutical and clinical antibody samples. This will focus on glycoprotein purification, followed by glycan or glycopeptide generation, derivatization and enrichment. The use of liquid-handling robots for glycomics studies on other sample types beyond antibodies will not be discussed here. We will summarize our thoughts on the current status of the field and explore the benefits and challenges associated with developing and using automated platforms for sample preparation. Finally, the future outlook for the automation of glycomics will be discussed along with a projected impact on the field in general.
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Affiliation(s)
- Jenifer L Hendel
- Ludger Limited, Culham Science Centre, Abingdon, Oxfordshire, UK
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15
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Deschepper FM, Zoppi R, Pirro M, Hensbergen PJ, Dall’Olio F, Kotsias M, Gardner RA, Spencer DI, Videira PA. L1CAM as an E-selectin Ligand in Colon Cancer. Int J Mol Sci 2020; 21:ijms21218286. [PMID: 33167483 PMCID: PMC7672641 DOI: 10.3390/ijms21218286] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
Metastasis is the main cause of death among colorectal cancer (CRC) patients. E-selectin and its carbohydrate ligands, including sialyl Lewis X (sLeX) antigen, are key players in the binding of circulating tumor cells to the endothelium, which is one of the major events leading to organ invasion. Nevertheless, the identity of the glycoprotein scaffolds presenting these glycans in CRC remains unclear. In this study, we firstly have characterized the glycoengineered cell line SW620 transfected with the fucosyltransferase 6 (FUT6) coding for the α1,3-fucosyltransferase 6 (FUT6), which is the main enzyme responsible for the synthesis of sLeX in CRC. The SW620FUT6 cell line expressed high levels of sLeX antigen and E-selectin ligands. Moreover, it displayed increased migration ability. E-selectin ligand glycoproteins were isolated from the SW620FUT6 cell line, identified by mass spectrometry, and validated by flow cytometry and Western blot (WB). The most prominent E-selectin ligand we identified was the neural cell adhesion molecule L1 (L1CAM). Previous studies have shown association of L1CAM with metastasis in cancer, thus the novel role as E-selectin counter-receptor contributes to understand the molecular mechanism involving L1CAM in metastasis formation.
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Affiliation(s)
- Fanny M. Deschepper
- Unidade de Ciências Biomoleculares Aplicadas (UCIBIO), Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; (F.M.D.); (R.Z.)
| | - Roberta Zoppi
- Unidade de Ciências Biomoleculares Aplicadas (UCIBIO), Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; (F.M.D.); (R.Z.)
| | - Martina Pirro
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (M.P.); (P.J.H.)
| | - Paul J. Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (M.P.); (P.J.H.)
| | - Fabio Dall’Olio
- Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, 40138 Bologna, Italy;
| | - Maximillianos Kotsias
- Ludger Ltd., Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, UK; (M.K.); (R.A.G.); (D.I.R.S.)
| | - Richard A. Gardner
- Ludger Ltd., Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, UK; (M.K.); (R.A.G.); (D.I.R.S.)
| | - Daniel I.R. Spencer
- Ludger Ltd., Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, UK; (M.K.); (R.A.G.); (D.I.R.S.)
| | - Paula A. Videira
- Unidade de Ciências Biomoleculares Aplicadas (UCIBIO), Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; (F.M.D.); (R.Z.)
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), 2829-516 Caparica, Portugal
- Correspondence:
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16
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Rebello OD, Gardner RA, Urbanowicz PA, Bolam DN, Crouch LI, Falck D, Spencer DIR. A novel glycosidase plate-based assay for the quantification of galactosylation and sialylation on human IgG. Glycoconj J 2020; 37:691-702. [PMID: 33064245 PMCID: PMC7679266 DOI: 10.1007/s10719-020-09953-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/28/2020] [Accepted: 10/06/2020] [Indexed: 02/06/2023]
Abstract
Changes in human IgG galactosylation and sialylation have been associated with several inflammatory diseases which are a major burden on the health care system. A large body of work on well-established glycomic and glycopeptidomic assays has repeatedly demonstrated inflammation-induced changes in IgG glycosylation. However, these assays are usually based on specialized analytical instrumentation which could be considered a technical barrier for uptake by some laboratories. Hence there is a growing demand for simple biochemical assays for analyzing these glycosylation changes. We have addressed this need by introducing a novel glycosidase plate-based assay for the absolute quantification of galactosylation and sialylation on IgG. IgG glycoproteins are treated with specific exoglycosidases to release the galactose and/or sialic acid residues. The released galactose monosaccharides are subsequently used in an enzymatic redox reaction that produces a fluorescence signal that is quantitative for the amount of galactosylation and, in-turn, sialylation on IgG. The glycosidase plate-based assay has the potential to be a simple, initial screening assay or an alternative assay to the usage of high-end analytical platforms such as HILIC-FLD-MSn when considering the analysis of galactosylation and sialylation on IgG. We have demonstrated this by comparing our assay to an industrial established HILIC-FLD-MSn glycomic analysis of 15 patient samples and obtained a Pearson’s r correlation coefficient of 0.8208 between the two methods.
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Affiliation(s)
- Osmond D Rebello
- Ludger Ltd, Culham Science Centre, Abingdon, UK. .,Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands.
| | | | | | - David N Bolam
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Lucy I Crouch
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - David Falck
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands
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17
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Rebello OD, Nicolardi S, Lageveen-Kammeijer GSM, Nouta J, Gardner RA, Mesker WE, Tollenaar RAEM, Spencer DIR, Wuhrer M, Falck D. A Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Assay for the Relative Quantitation of Antennary Fucosylated N-Glycans in Human Plasma. Front Chem 2020; 8:138. [PMID: 32185163 PMCID: PMC7059190 DOI: 10.3389/fchem.2020.00138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 02/14/2020] [Indexed: 12/29/2022] Open
Abstract
Changes in the abundance of antennary fucosylated glycans in human total plasma N-glycome (TPNG) have been associated with several diseases ranging from diabetes to various forms of cancer. However, it is challenging to address this important part of the human glycome. Most commonly, time-consuming chromatographic separations are performed to differentially quantify core and antenna fucosylation. Obtaining sufficient resolution for larger, more complex glycans can be challenging. We introduce a matrix-assisted laser desorption/ionization—mass spectrometry (MALDI-MS) assay for the relative quantitation of antennary fucosylation in TPNG. N-linked glycans are released from plasma by PNGase F and further treated with a core fucosidase before performing a linkage-informative sialic acid derivatization. The core fucosylated glycans are thus depleted while the remaining antennary fucosylated glycans are quantitated. Simultaneous quantitation of α2,3-linked sialic acids and antennary fucosylation allows an estimation of the sialyl-Lewis x motif. The approach is feasible using either ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry or time-of-flight mass spectrometry. The assay was used to investigate changes of antennary fucosylation as clinically relevant marker in 14 colorectal cancer patients. In accordance with a previous report, we found elevated levels of antennary fucosylation pre-surgery which decreased after tumor resection. The assay has the potential for revealing antennary fucosylation signatures in various conditions including diabetes and different types of cancer.
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Affiliation(s)
- Osmond D Rebello
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands.,Ludger Ltd, Culham Science Centre, Abingdon, United Kingdom
| | - Simone Nicolardi
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands
| | | | - Jan Nouta
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands
| | | | - Wilma E Mesker
- Department of Surgery, Leiden University Medical Center, Leiden, Netherlands
| | - Rob A E M Tollenaar
- Department of Surgery, Leiden University Medical Center, Leiden, Netherlands
| | | | - Manfred Wuhrer
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands
| | - David Falck
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, Netherlands
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18
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Kotsias M, Kozak RP, Gardner RA, Wuhrer M, Spencer DIR. Improved and semi-automated reductive β-elimination workflow for higher throughput protein O-glycosylation analysis. PLoS One 2019; 14:e0210759. [PMID: 30653606 PMCID: PMC6336230 DOI: 10.1371/journal.pone.0210759] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 01/01/2019] [Indexed: 11/19/2022] Open
Abstract
Protein O-glycosylation has shown to be critical for a wide range of biological processes, resulting in an increased interest in studying the alterations in O-glycosylation patterns of biological samples as disease biomarkers as well as for patient stratification and personalized medicine. Given the complexity of O-glycans, often a large number of samples have to be analysed in order to obtain conclusive results. However, most of the O-glycan analysis work done so far has been performed using glycoanalytical technologies that would not be suitable for the analysis of large sample sets, mainly due to limitations in sample throughput and affordability of the methods. Here we report a largely automated system for O-glycan analysis. We adapted reductive β-elimination release of O-glycans to a 96-well plate system and transferred the protocol onto a liquid handling robot. The workflow includes O-glycan release, purification and derivatization through permethylation followed by MALDI-TOF-MS. The method has been validated according to the ICH Q2 (R1) guidelines for the validation of analytical procedures. The semi-automated reductive β-elimination system enabled for the characterization and relative quantitation of O-glycans from commercially available standards. Results of the semi-automated method were in good agreement with the conventional manual in-solution method while even outperforming it in terms of repeatability. Release of O-glycans for 96 samples was achieved within 2.5 hours, and the automated data acquisition on MALDI-TOF-MS took less than 1 minute per sample. This largely automated workflow for O-glycosylation analysis showed to produce rapid, accurate and reliable data, and has the potential to be applied for O-glycan characterization of biological samples, biopharmaceuticals as well as for biomarker discovery.
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Affiliation(s)
| | - Radoslaw P. Kozak
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Richard A. Gardner
- Ludger Ltd, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Manfred Wuhrer
- Leiden University Medical Centre, Centre for Proteomics and Metabolomics, Leiden, Netherlands
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19
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Reiding KR, Bondt A, Hennig R, Gardner RA, O'Flaherty R, Trbojević-Akmačić I, Shubhakar A, Hazes JMW, Reichl U, Fernandes DL, Pučić-Baković M, Rapp E, Spencer DIR, Dolhain RJEM, Rudd PM, Lauc G, Wuhrer M. High-throughput Serum N-Glycomics: Method Comparison and Application to Study Rheumatoid Arthritis and Pregnancy-associated Changes. Mol Cell Proteomics 2019; 18:3-15. [PMID: 30242110 PMCID: PMC6317482 DOI: 10.1074/mcp.ra117.000454] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 05/14/2018] [Indexed: 11/06/2022] Open
Abstract
N-Glycosylation is a fundamentally important protein modification with a major impact on glycoprotein characteristics such as serum half-life and receptor interaction. More than half of the proteins in human serum are glycosylated, and the relative abundances of protein glycoforms often reflect alterations in health and disease. Several analytical methods are currently capable of analyzing the total serum N-glycosylation in a high-throughput manner.Here we evaluate and compare the performance of three high-throughput released N-glycome analysis methods. Included were hydrophilic-interaction ultra-high-performance liquid chromatography with fluorescence detection (HILIC-UHPLC-FLD) with 2-aminobenzamide labeling of the glycans, multiplexed capillary gel electrophoresis with laser-induced fluorescence detection (xCGE-LIF) with 8-aminopyrene-1,3,6-trisulfonic acid labeling, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) with linkage-specific sialic acid esterification. All methods assessed the same panel of serum samples, which were obtained at multiple time points during the pregnancies and postpartum periods of healthy women and patients with rheumatoid arthritis (RA). We compared the analytical methods on their technical performance as well as on their ability to describe serum protein N-glycosylation changes throughout pregnancy, with RA, and with RA disease activity.Overall, the methods proved to be similar in their detection and relative quantification of serum protein N-glycosylation. However, the non-MS methods showed superior repeatability over MALDI-TOF-MS and allowed the best structural separation of low-complexity N-glycans. MALDI-TOF-MS achieved the highest throughput and provided compositional information on higher-complexity N-glycans. Consequentially, MALDI-TOF-MS could establish the linkage-specific sialylation differences within pregnancy and RA, whereas HILIC-UHPLC-FLD and xCGE-LIF demonstrated differences in α1,3- and α1,6-branch galactosylation. While the combination of methods proved to be the most beneficial for the analysis of total serum protein N-glycosylation, informed method choices can be made for the glycosylation analysis of single proteins or samples of varying complexity.
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Affiliation(s)
| | - Albert Bondt
- From the ‡Center for Proteomics and Metabolomics,; §Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - René Hennig
- ¶Max Planck Institute (MPI) for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;; ‖glyXera GmbH., 39120 Magdeburg, Germany
| | - Richard A Gardner
- **Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Roisin O'Flaherty
- ‡‡GlycoScience Group, National Institute for Bioprocessing Research and Training (NIBRT), Fosters Avenue, Blackrock, Co. Dublin, Ireland
| | | | - Archana Shubhakar
- **Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Johanna M W Hazes
- ¶¶Department of Rheumatology, Erasmus University Medical Center, Rotterdam, The Netherland
| | - Udo Reichl
- ¶Max Planck Institute (MPI) for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;; ‖‖Otto von Guericke University Magdeburg, Chair of Bioprocess Engineering, 39106 Magdeburg, Germany
| | - Daryl L Fernandes
- **Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | | | - Erdmann Rapp
- ¶Max Planck Institute (MPI) for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;; ‖glyXera GmbH., 39120 Magdeburg, Germany
| | - Daniel I R Spencer
- **Ludger, Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Radboud J E M Dolhain
- ¶¶Department of Rheumatology, Erasmus University Medical Center, Rotterdam, The Netherland
| | - Pauline M Rudd
- ‡‡GlycoScience Group, National Institute for Bioprocessing Research and Training (NIBRT), Fosters Avenue, Blackrock, Co. Dublin, Ireland
| | - Gordan Lauc
- §§Genos Glycoscience Research Laboratory, Zagreb, Croatia;; ***Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
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Crescioli S, Chiaruttini G, Mele S, Ilieva KM, Pellizzari G, Spencer DIR, Gardner RA, Lacy KE, Spicer JF, Tutt ANJ, Wagner GK, Karagiannis SN. Engineering and stable production of recombinant IgE for cancer immunotherapy and AllergoOncology. J Allergy Clin Immunol 2018; 141:1519-1523.e9. [PMID: 29360527 PMCID: PMC6286379 DOI: 10.1016/j.jaci.2017.12.986] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 12/09/2017] [Accepted: 12/18/2017] [Indexed: 02/07/2023]
Affiliation(s)
- Silvia Crescioli
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom; NIHR Biomedical Research Centre at Guy's and St Thomas's Hospitals and King's College London, London, United Kingdom
| | - Giulia Chiaruttini
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom
| | - Silvia Mele
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom
| | - Kristina M Ilieva
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom; Breast Cancer Now Unit, School of Cancer & Pharmaceutical Sciences, King's College London, Guy's Cancer Centre, London, United Kingdom
| | - Giulia Pellizzari
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom
| | | | | | - Katie E Lacy
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom
| | - James F Spicer
- School of Cancer & Pharmaceutical Sciences, King's College London, Guy's Hospital, London, United Kingdom
| | - Andrew N J Tutt
- Breast Cancer Now Unit, School of Cancer & Pharmaceutical Sciences, King's College London, Guy's Cancer Centre, London, United Kingdom; Breast Cancer Now Toby Robins Research Centre, Institute of Cancer Research, London, United Kingdom
| | - Gerd K Wagner
- Department of Chemistry, Faculty of Natural & Mathematical Sciences, King's College London, London, United Kingdom
| | - Sophia N Karagiannis
- St John's Institute of Dermatology, School of Basic & Medical Biosciences, King's College London, London, United Kingdom; NIHR Biomedical Research Centre at Guy's and St Thomas's Hospitals and King's College London, London, United Kingdom; Breast Cancer Now Unit, School of Cancer & Pharmaceutical Sciences, King's College London, Guy's Cancer Centre, London, United Kingdom.
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Thomson RI, Gardner RA, Strohfeldt K, Fernandes DL, Stafford GP, Spencer DIR, Osborn HMI. Analysis of Three Epoetin Alpha Products by LC and LC-MS Indicates Differences in Glycosylation Critical Quality Attributes, Including Sialic Acid Content. Anal Chem 2017; 89:6455-6462. [PMID: 28509534 DOI: 10.1021/acs.analchem.7b00353] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Erythropoietin (EPO) is one of the main therapeutics used to treat anemic patients, greatly improving their quality of life. In this study, biosimilars Binocrit and a development product, called here CIGB-EPO, were compared to the originator product, Eprex. All three are epoetin alpha products, reputed to have similar glycosylation profiles. The quality, safety, and efficacy of this biotherapeutic depend on the following glycosylation critical quality attributes (GCQAs): sialylation, N-glycolyl-neuraminic acid (Neu5Gc) content, branching, N-acetyl-lactosamine (LacNAc) extensions, and O-acetylation pattern. Reverse-phase ultra-high-pressure liquid chromatography (RP-UHPLC) analysis of acid-released, 1,2-diamino-4,5-methylenedioxybenzene (DMB) labeled sialic acid derivatives and hydrophilic interaction liquid chromatography (HILIC) in combination with mass spectrometry (HILIC-UHPLC-MS) of procainamide (PROC) labeled N-glycans were the analytical tools used. An automated method for enzymatic release and PROC labeling was applied for the first time to the erythropoiesis stimulating agent (ESA) products, which facilitated novel, in-depth characterization, and allowed identification of precise structural features including the location of O-acetyl groups on sialic acid (SA) moieties. Samples were digested by a sialate-O-acetylesterase (NanS) to confirm the presence of O-acetyl groups. It was found that Eprex contained the greatest relative abundance of O-acetylated derivatives, Binocrit expressed the least Neu5Gc, and CIGB-EPO showed the greatest variety of high-mannose-phosphate structures. The sialylation and LacNAc extension patterns of the three ESAs were similar, with a maximum of four N-acetyl-neuraminic acid (Neu5Ac) moieties detected per glycan. Such differences in SA derivatization, particularly O-acetylation, could have consequences for the quality and safety of a biotherapeutic, as well as its efficacy.
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Affiliation(s)
- Rebecca I Thomson
- Reading School of Pharmacy, University of Reading , Reading, Berkshire RG6 6AP, United Kingdom
| | - Richard A Gardner
- Ludger, Ltd. , Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, United Kingdom
| | - Katja Strohfeldt
- Reading School of Pharmacy, University of Reading , Reading, Berkshire RG6 6AP, United Kingdom
| | - Daryl L Fernandes
- Ludger, Ltd. , Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, United Kingdom
| | - Graham P Stafford
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield , Sheffield, S10 2TA, United Kingdom
| | - Daniel I R Spencer
- Ludger, Ltd. , Culham Science Centre, Abingdon, Oxfordshire OX14 3EB, United Kingdom
| | - Helen M I Osborn
- Reading School of Pharmacy, University of Reading , Reading, Berkshire RG6 6AP, United Kingdom
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Ventham NT, Gardner RA, Kennedy NA, Shubhakar A, Kalla R, Nimmo ER, Fernandes DL, Satsangi J, Spencer DIR. Correction: changes to serum sample tube and processing methodology does not cause inter-individual variation in automated whole serum N-glycan profiling in health and disease. PLoS One 2015; 10:e0129335. [PMID: 26030157 PMCID: PMC4451143 DOI: 10.1371/journal.pone.0129335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Kozak RP, Royle L, Gardner RA, Bondt A, Fernandes DL, Wuhrer M. Improved nonreductive O-glycan release by hydrazinolysis with ethylenediaminetetraacetic acid addition. Anal Biochem 2014; 453:29-37. [PMID: 24613257 DOI: 10.1016/j.ab.2014.02.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 02/23/2014] [Accepted: 02/26/2014] [Indexed: 10/25/2022]
Abstract
The study of protein O-glycosylation is receiving increasing attention in biological, medical, and biopharmaceutical research. Improved techniques are required to allow reproducible and quantitative analysis of O-glycans. An established approach for O-glycan analysis relies on their chemical release in high yield by hydrazinolysis, followed by fluorescent labeling at the reducing terminus and high-performance liquid chromatography (HPLC) profiling. However, an unwanted degradation known as "peeling" often compromises hydrazinolysis for O-glycan analysis. Here we addressed this problem using low-molarity solutions of ethylenediaminetetraacetic acid (EDTA) in hydrazine for O-glycan release. O-linked glycans from a range of different glycoproteins were analyzed, including bovine fetuin, bovine submaxillary gland mucin, and serum immunoglobulin A (IgA). The data for the O-glycans released by hydrazine with anhydrous EDTA or disodium salt dihydrate EDTA show high yields of the native O-glycans compared with the peeled product, resulting in a markedly increased robustness of the O-glycan profiling method. The presented method for O-glycan release demonstrates significant reduction in peeling and reduces the number of sample handling steps prior to release.
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Affiliation(s)
| | - Louise Royle
- Ludger, Culham Science Centre, Oxfordshire OX14 3EB, UK
| | | | - Albert Bondt
- Department of Rheumatology, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands; Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZC Leiden, The Netherlands
| | | | - Manfred Wuhrer
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZC Leiden, The Netherlands; Division of Bioanalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
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Zauner G, Kozak RP, Gardner RA, Fernandes DL, Deelder AM, Wuhrer M. Protein O-glycosylation analysis. Biol Chem 2013; 393:687-708. [PMID: 22944673 DOI: 10.1515/hsz-2012-0144] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 06/05/2012] [Indexed: 11/15/2022]
Abstract
This review provides an overview on the methods available for analysis of O-glycosylation. Three major themes are addressed: analysis of released O-glycans including different O-glycan liberation, derivatization, and detection methods; analysis of formerly O-glycosylated peptides yielding information on O-glycan attachment sites; analysis of O-glycopeptides, representing by far the most informative but also most challenging approach for O-glycan analysis. Although there are various techniques available for the identification of O-linked oligosaccharides, the focus here is on MS fragmentation techniques such as collision-induced fragmentation, electron capture dissociation, and electron transfer dissociation. Finally, the O-glycan analytical challenges that need to be met will be discussed.
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Affiliation(s)
- Gerhild Zauner
- Biomolecular Mass Spectrometry Unit, Department of Parasitology, Leiden University Medical Center, P.O. Box 9600, NL-2300 RC Leiden, The Netherlands
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Kozak RP, Royle L, Gardner RA, Fernandes DL, Wuhrer M. Suppression of peeling during the release of O-glycans by hydrazinolysis. Anal Biochem 2012; 423:119-28. [PMID: 22306471 DOI: 10.1016/j.ab.2012.01.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/20/2011] [Accepted: 01/04/2012] [Indexed: 11/27/2022]
Abstract
The analysis of O-glycans is essential for better understanding their functions in biological processes. Although many techniques for O-glycan release have been developed, the hydrazinolysis release method is the best for producing O-glycans with free reducing termini in high yield. This release technique allows the glycans to be labeled with a fluorophore and analyzed by fluorescence detection. Under the hydrazinolysis release conditions, a side reaction is observed and causes the loss of monosaccharides from the reducing terminus of the glycans (known as peeling). Using bovine fetuin (because it contains the sialylated O-glycans most commonly found on biopharmaceuticals) and bovine submaxillary gland mucin (BSM), here we demonstrate that peeling can be greatly reduced when the sample is buffer exchanged prior to hydrazinolysis with solutions of either 0.1% trifluoroacetic acid (TFA) or low-molarity (100, 50, 20, and 5 mM) ethylenediaminetetraacetic acid (EDTA). The addition of calcium chloride to fetuin resulted in an increase in peeling, whereas subsequent washing with EDTA abolished this effect, suggesting a role of calcium and possibly other cations in causing peeling. The presented technique for sample preparation prior to hydrazinolysis greatly reduces the level of undesirable cleavage products in O-glycan analysis and increases the robustness of the method.
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Geden SE, Gardner RA, Fabbrini MS, Ohashi M, Phanstiel Iv O, Teter K. Lipopolyamine treatment increases the efficacy of intoxication with saporin and an anticancer saporin conjugate. FEBS J 2007; 274:4825-36. [PMID: 17714513 DOI: 10.1111/j.1742-4658.2007.06008.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Saporin is a type I ribosome-inactivating protein that is often appended with a cell-binding domain to specifically target and kill cancer cells. Urokinase plasminogen activator (uPA)-saporin, for example, is an anticancer toxin that consists of a chemical conjugate between the human uPA and native saporin. Both saporin and uPA-saporin enter the target cell by endocytosis and must then escape the endomembrane system to reach the cytosolic ribosomes. The latter process may represent a rate-limiting step for intoxication and would therefore directly affect toxin potency. In the present study, we document two treatments (shock with dimethylsulfoxide and lipopolyamine coadministration) that generate substantial cellular sensitization to saporin/uPA-saporin. With the use of lysosome-endosome X (LEX)1 and LEX2 mutant cell lines, an endosomal trafficking step preceding cargo delivery to the late endosomes was identified as a major site for the dimethylsulfoxide-facilitated entry of saporin into the cytosol. Dimethylsulfoxide and lipopolyamines are known to disrupt the integrity of endosome membranes, so these reagents could facilitate the rapid movement of toxin from permeabilized endosomes to the cytosol. However, the same pattern of toxin sensitization was not observed for dimethylsulfoxide- or lipopolyamine-treated cells exposed to diphtheria toxin, ricin, or the catalytic A chain of ricin. The sensitization effects were thus specific for saporin, suggesting a novel mechanism of saporin translocation by endosome disruption. Lipopolyamines have been developed as in vivo gene therapy vectors; thus, lipopolyamine coadministration with uPA-saporin or other saporin conjugates could represent a new approach for anticancer toxin treatments.
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Affiliation(s)
- Sandra E Geden
- Department of Molecular Biology and Microbiology and Biomolecular Science Center, University of Central Florida, FL, USA
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Gardner RA, Ghobrial G, Naser SA, Phanstiel O. Synthesis and Biological Evaluation of New Acinetoferrin Homologues for Use as Iron Transport Probes in Mycobacteria. J Med Chem 2004; 47:4933-40. [PMID: 15369397 DOI: 10.1021/jm049805y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Four new acinetoferrin homologues were synthesized using a modular synthetic approach. Two linear and two cyclic imide derivatives were generated and evaluated for growth stimulating behavior in Mycobacterium avium subsp paratuberculosis. The yield for the tandem coupling of a functionalized aminohydroxamic acid motif (2 equiv) to a tert-butyl citrate derivative was significantly improved using DCC and N-hydroxysuccinimide. (1)H NMR spectroscopy (CD(3)OD) provided a convenient method for monitoring the final imidization step in TFA using the doublet patterns between 2.5 and 3.06 ppm. New protocols demonstrated that only a 20% growth enhancement was observed with M. avium subsp. paratuberculosis using the imide of acinetoferrin. Last, a siderophore from Streptomyces pilosus, deferrioxamine B, was shown to cross-feed M. avium subsp. paratuberculosis with the same efficiency as the more costly, native chelator, mycobactin J.
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Affiliation(s)
- Richard A Gardner
- Department of Chemistry and Department of Molecular Biology and Microbiology, University of Central Florida, Orlando, Florida 32816-2366, USA
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Abstract
The False Memory Syndrome (FMS) diagnosis was very much in vogue from the late 1980s to the mid-1990s. It was an outgrowth of the belief held by many therapists that childhood sexual abuse was one of the most common causes of all forms of psychopathology. Although no longer in-vogue, the diagnosis is more recently being used for people who are falsely claiming that they were sexually abused by their priests. As was true in the earlier era, there were indeed many people who were sexually abused in childhood, but there were also many who were not and actually came to believe that they were, especially under the influence of therapists conducting "repressed memory therapy." Similarly, sexual abuse by priests has been a widespread phenomenon. Yet, there are still false accusers who are being led to believe by their overzealous therapists that they were indeed abused. As a psychoanalyst who has been asked to do forensic evaluations in many of these cases, I automatically ask myself questions about the psychodynamics of such falsely accusing patients. Here I describe those psychodynamic factors that I believe were operative in FMS cases, factors which in some cases apply to false sex abuse accusation against priests. Accordingly, this article is not simply of historical interest, but is still relevant and timely.
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Gardner RA. Interview criteria for assessing allegations of sexual abuse in children and adults. J Am Acad Psychoanal Dyn Psychiatry 2003; 31:297-323. [PMID: 12866693 DOI: 10.1521/jaap.31.2.297.22112] [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] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Freud's dilemma with regard to whether or not he should believe his patients' allegations of sexual abuse in childhood is well known. A century later, psychoanalysts are still dealing with this important issue. In this article, I describe the criteria I have developed in recent years, criteria that have been useful for me when attempting to determine whether my child and adult patients' allegations of sex abuse are more likely to be true or more likely to be false. Although these differentiating criteria were developed in the context of forensic evaluations, they should prove useful in clinical settings as well.
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Vargas HI, Dooley WC, Gardner RA, Gonzalez KD, Heywang-Köbrunner SH, Fenn AJ. Success of sentinel lymph node mapping after breast cancer ablation with focused microwave phased array thermotherapy. Am J Surg 2003; 186:330-2. [PMID: 14553844 DOI: 10.1016/s0002-9610(03)00267-8] [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] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Breast cancer tumor ablation as part of a multimodality approach in the treatment of breast cancer is the subject of recent interest. This study was conducted to determine if the ability to perform sentinel node biopsy was impaired after thermal-induced ablation of breast cancer. METHODS We studied patients who had sentinel node biopsy after preoperative focused microwave phased array for breast cancer ablation. RESULTS Twenty-one patients with T1-T2 breast cancer and clinically negative axilla underwent wide local excision and sentinel node biopsy guided by blue dye and sulfur colloid. Surgery was done an average of 17 days after microwave ablation. Fifteen of 22 patients (68%) had histologic evidence of tumor necrosis. Sentinel lymph node mapping was successful in 19 of 21 patients (91%). Axillary metastases were detected in 42% of cases. CONCLUSIONS This study documents successful sentinel lymph node mapping for patients treated with antecedent local tumor ablation using focused microwave phased array ablation.
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Affiliation(s)
- Hernan I Vargas
- Division of Surgical Oncology, Harbor-UCLA Medical Center, 1000 W Carson St, Torrance, CA 90509, USA.
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Clegg RA, Gardner RA, Sumathipala RN, Lavialle F, Boisgard R, Ollivier-Bousquet M. Targeting of PKA in mammary epithelial cells. Mechanisms and functional consequences. Adv Exp Med Biol 2001; 480:99-105. [PMID: 10959415 DOI: 10.1007/0-306-46832-8_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Targeting of protein kinases, promoting association with specific partner-molecules and localisation to particular sites within the cell, has come to be recognised as a key mechanism for attributing specificity to these enzymes. In mammary epithelial cells, the repertoire of acute regulatory roles played by cyclic AMP-dependent protein kinase (PKA) differs from that in other lipogenic cell-types. Furthermore, PKA is implicated in the regulation of mammary-specific function, mediating a tonic stimulation of the flux of newly-synthesised casein through its basal secretory pathway. Both these observations imply mammary-specific properties of either PKA targeting systems or of PKA itself. Evidence for the latter is currently lacking. Pulse-chase labelling experiments in the presence and absence of selective effectors of PKA have enabled the site(s) of action of this protein kinase on casein secretion to be localised to the early stages of the secretory pathway. Possible mechanisms are considered for the physical targeting of PKA to the membrane-enclosed components of the secretory pathway and evidence for their occurrence in mammary epithelial cells is presented.
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Affiliation(s)
- R A Clegg
- Hannah Research Institute, Ayr, Scotland, UK
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Abstract
Cross-fostered as infants in Reno, Nevada, chimpanzees (Pan troglodytes) Washoe, Moja, Tatu, and Dar freely converse in signs of American Sign Language with each other as well as with humans in Ellensburg, Washington. In this experiment, a human interlocutor waited for a chimpanzee to initiate conversations with her and then responded with 1 of 4 types of probes: general requests for more information, on-topic questions, off-topic questions, or negative statements. The responses of the chimpanzees to the probes depended on the type of probe and the particular signs in the probes. They reiterated, adjusted, and shifted the signs in their utterances in conversationally appropriate rejoinders. Their reactions to and interactions with a conversational partner resembled patterns of conversation found in similar studies of human children.
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Affiliation(s)
- M L Jensvold
- Chimpanzee and Human Communication Institute, Central Washington University, Ellensburg 98926, USA.
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Gardner RA, Kruyer WB, Pickard JS, Celio PV. Nonsustained ventricular tachycardia in 193 U.S. military aviators: long-term follow-up. Aviat Space Environ Med 2000; 71:783-90. [PMID: 10954354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
BACKGROUND Despite its importance to the aeromedical community, the occupational implications of asymptomatic, nonsustained ventricular tachycardia (VT) are not well described. We sought to clarify this issue via a review of military aviators evaluated for nonsustained VT by defining event rates for sudden cardiac death, syncope, presyncope and sustained VT, and by determining whether any cofactors predicted a subgroup at increased risk for such outcomes. METHODS We reviewed the records of 193 military aviators evaluated at the U.S. Air Force Aeromedical Consultation Service for nonsustained VT from September 1960 to December 1992. Follow-up information was available on 192 of the 193 aviators over a mean of 10.6 yr. Cofactor analysis focused on idiopathic VT (no associated underlying cardiac disease) and VT associated with mitral valve prolapse (MVP). RESULTS There was no documented sustained VT; 9 (4.6%) had events including syncope (1), presyncope (5) and sudden death (3). Of these 9, 4 had idiopathic VT. The 3 deaths were associated with coronary artery disease, MVP and cardiomyopathy. No cofactors predicted events in aviators initially presenting with asymptomatic nonsustained VT. For asymptomatic nonsustained VT, the maximum predicted annual event rate was 0.33% for idiopathic VT and 2.3% for VT with MVP (95% confidence limit). CONCLUSIONS Nonsustained VT did not predict future documented sustained VT. Cofactors failed to predict a subgroup at increased risk for events. Idiopathic nonsustained VT appeared to be a low risk population for whom expanded waiver criteria are proposed with suggested limits on duration and number of episodes of VT.
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Affiliation(s)
- R A Gardner
- Internal Medicine Branch, Aeromedical Consultation Service, USAF School of Aerospace Medicine, Brooks AFB, TX, USA
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Abstract
The conventional adolescent orthodontic patient is treated during a phase of active growth, but growth of the skeletodental complex continues after treatment and into adulthood at a much slower pace. Selection of orthodontic diagnostic and treatment regimens that produce stable and esthetic dental relationships is a continual endeavor for the orthodontic specialist. Patients should be recalled for long periods of time and the results evaluated. The present longitudinal study was completed on 36 individuals, all of whom had received comprehensive orthodontic treatment. Dental changes were assessed from cephalograms for the in-treatment period (ca. 12 to 15 years of age), posttreatment to first recall (0 = 22 years of age), and first to second recall period (0 = 30 years of age). There was considerable change in the absolute locations of the teeth, but, in reality, these changes are almost wholly attributable to growth of the bony reference structures, not dental changes per se. Growth proceeded at a very slow pace after the first recall (ca. 22 to 30 years of age ). Dental relationships, eg., FMIA, IMPA, 6L angulation, exhibited no systematic change after treatment.
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40
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Abstract
Despite its quantitative importance in the secretion of lactoproteins, little is known about the triggering and control mechanisms that initiate, regulate and terminate the operation of the basal pathway of lactoprotein secretion throughout the lactation cycle. This study investigated the possible modulation by cAMP-mediated mechanisms, of cellular transit of newly-synthesised caseins and their basal secretion in explants of mammary tissue from lactating rats and rabbits. Enhancement of the rate of secretion of newly-synthesised caseins occurs when mammary explants are challenged in vitro with agents that activate protein kinase A (PKA). Inhibition of PKA slows casein secretion. The PKA-sensitive step(s) in casein secretion is early in the exocytosis pathway but inhibition of PKA does not impair casein maturation. Ultrastructural, immunochemical and biochemical methods locate PKA on membranes of vesicles situated in the Golgi region. Exposure of tissue to a cell-permeant PKA inhibitor results in morphological modification of these vesicular structures. We conclude that PKA mediates tonic positive regulation of the basal secretory pathway for lactoproteins in the mammary epithelial cell.
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Affiliation(s)
- R A Clegg
- Hannah Research Institute, Ayr, Scotland, UK.
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41
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Gardner RA. The Burgess decision and the Wallerstein brief. J Am Acad Psychiatry Law 1998; 26:425-431. [PMID: 9785286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Divorcing couples traditionally incorporate into their settlement contracts a stipulation regarding relative degree of freedom to relocate, especially if the relocating parent has primary custody of the children. Typically, the primary custodial parent might be restricted from moving outside of the state in which the divorcing couple has resided, or there may be a specific mile radius or travel time radius beyond which the primary custodial parent cannot relocate. In recent years, courts have become increasingly permissive with regard to allowing relocation by primary custodial parents, and the once stringent requirements that needed to be satisfied to justify relocation are being progressively relaxed. In 1996, the Supreme Court of California in In Re the Marriage of Burgess, 913 P.2d 473 (Cal. 1996), has set a precedent for even further relaxation of these once rigid restrictions. The Burgess decision has been frequently quoted in the State of California and is receiving widespread attention elsewhere. It is the author's opinion that this precedent is ill conceived and will most likely result in significant grief and suffering for the nonrelocating parent as well as the relocating children.
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Affiliation(s)
- R A Gardner
- Columbia University College of Physicians and Surgeons, New York City, USA
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Affiliation(s)
- R A Gardner
- Columbia University College of Physicians and Surgeons, USA
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Gardner RA, Heathcote R St A. An experimental investigation of uroselectan B. 1932. Br J Radiol 1995; 68:H142-55. [PMID: 7496679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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Gardner RA, Travers MT, Barber MC, Miller WR, Clegg RA. Expression of PK-A catalytic and regulatory subunits in lactating rat mammary tissue: effects of litter removal. Biochem Soc Trans 1995; 23:452S. [PMID: 8566343 DOI: 10.1042/bst023452s] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Affiliation(s)
- R A Gardner
- Cambridge Scientific Abstracts, Bethesda, MD 20814, USA
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Gardner RA, Travers MT, Barber MC, Miller WR, Clegg RA. Cyclic AMP-dependent protein kinase in rat mammary tissue: expression of catalytic and regulatory subunits throughout pregnancy and lactation. Biochem J 1994; 301 ( Pt 3):807-12. [PMID: 8053905 PMCID: PMC1137059 DOI: 10.1042/bj3010807] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
'Expressed' and 'total' activities of cyclic AMP-dependent protein kinase (PK-A) were measured in extracts of rat mammary tissue sampled throughout pregnancy and lactation. Expression of the genes encoding the catalytic subunit (C-subunit) isoforms C alpha and C beta was examined by Northern blotting, as a function of mammary development, to determine relative levels of their respective mRNAs. The content of C-subunit protein (all isoforms) was estimated immunochemically and related to levels of C-subunit catalytic activity and of mRNAs. It was found that C-subunit isoform mRNAs are expressed co-ordinately during mammary development and that a marked decline in expression, per cell, at around parturition is paralleled by a fall in 'total' PK-A activity. The 'expressed' activity of PK-A activity underwent characteristic changes throughout pregnancy and lactation, reaching a peak late in pregnancy. The PK-A activity ratio reached a peak in early lactation. C-subunit protein mass closely parallel 'total' PK-A activity throughout pregnancy and lactation, thereby demonstrating the constancy of C-subunit specific catalytic activity during these developmental events. Regulatory subunits (R-subunits) were probed with the photoaffinity label 8-azido-[32P]cAMP. The abundance of R-II as a proportion of total R-subunit increased throughout pregnancy and lactation, and quantitative analysis of the photoaffinity labelling suggested inconstancy in the ratio of R:C subunits, with highest values occurring in late pregnancy/early lactation.
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Affiliation(s)
- R A Gardner
- Hannah Research Institute, Ayr, Scotland, U.K
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Gardner RA, Travers MT, Barber MC, Miller WR, Clegg RA. Expression of PK-A catalytic subunit in mammary tissue during pregnancy and lactation. Biochem Soc Trans 1993; 21:398S. [PMID: 8131974 DOI: 10.1042/bst021398s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Abstract
Two species of Schizotrypanum, T. (S.) dionisii and T. (S.) vespertilionis, were identified from British bats. Laboratory studies on stocks of isolated trypanosomes from 5 species of bat (Pipistrellus pipistrellus, Nyctalus leisleri, N. noctula, Eptesicus serotinus and Myotis brandti) indicated that the predominant species was T. d. dionisii. Collections and dissection of the bat bug Cimex pipistrelli from bat roosts revealed flagellate infection in a total of 12 out of 20 bugs; 7 of these bugs had metacyclic trypanosomes present. C. pipistrelli and the human bed bug, C. lectularius were reared in the laboratory and allowed to feed on wild-caught bats known to be infected with T. d. dionisii. Development occurred in both species of Cimex. Cimex spp. could be used to detect subpatent Schizotrypanum infections by xenodiagnosis. This technique was used to test the parasitological status of bats collected in the wild or reared in captivity. On a single occasion an apparent transmission of T. d. dionisii to an uninfected (by xenodiagnosis) laboratory reared bat was achieved. A stock of Schizotrypanum isolated from a wild-caught C. pipistrelli collected in a N. leisteri roost was identified by DNA buoyant density centrifugation as T. (S.) vespertilionis. A P. pipistrellus known to be infected with T. d. dionisii was found to have cyst-like structures in thoracic skeletal muscle containing amastigotes. The study provided the strongest evidence yet that C. pipistrelli is the vector of Schizotrypanum in British bats.
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Affiliation(s)
- R A Gardner
- Department of Biological Sciences, University of Salford
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Abstract
Polychromophilus murinus, a malaria parasite of Chiroptera is reported from Myotis daubentoni in England. The vector was suspected to be the ectoparasitic Nycteribiid fly, Nycteribia kolenatii. N. kolenatii collected from wild-caught M. daubentoni were found to have oocysts on the midgut and sporozoites in the salivary glands. Wild-caught N. kolenatii were maintained on two wild-caught M. daubentoni harbouring heavy (patent) infections of P. murinus; both oocysts and sporozoites were found in these flies. The mature oocysts measured 52-71 micron in diameter. Sporozoites were straight or slightly crescentic and had a mean length of 7.4 micron. Electron microscopy of immature and mature oocysts revealed a morphology similar to that of malaria parasites. Sporozoites were also similar in structure to Plasmodium sporozoites and were found in the epithelial cells of the salivary gland and within the lumen; a cytostome was present and transverse sections revealed 21 microtubules arranged evenly around the periphery. Sporozoites were observed within the basement membrane of the salivary gland of N. kolenatii; such sporozoites appeared to be penetrating the gland, a process hitherto not described in malaria parasites. Rickettsia-like bodies were found within the cytoplasm of the epithelial cells of the salivary gland. Exflagellation of microgametocytes was achieved. An ultrastructural study of the gametocytes revealed a structure similar to that described in other Haemoproteidae. A common feature of infected erythrocytes was a projecting erythrocyte membrane. Attempts to find schizogony in impression smears and sections of tissues of two infected M. daubentoni were not successful.
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Affiliation(s)
- R A Gardner
- Department of Biological Sciences, University of Salford
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