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Sabbah S, Liew A, Brooks AM, Kundu R, Reading JL, Flatt A, Counter C, Choudhary P, Forbes S, Rosenthal MJ, Rutter MK, Cairns S, Johnson P, Casey J, Peakman M, Shaw JA, Tree TIM. Autoreactive T cell profiles are altered following allogeneic islet transplantation with alemtuzumab induction and re-emerging phenotype is associated with graft function. Am J Transplant 2021; 21:1027-1038. [PMID: 32865886 DOI: 10.1111/ajt.16285] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 03/20/2020] [Revised: 07/15/2020] [Accepted: 08/10/2020] [Indexed: 01/25/2023]
Abstract
Islet transplantation is an effective therapy for life-threatening hypoglycemia, but graft function gradually declines over time in many recipients. We characterized islet-specific T cells in recipients within an islet transplant program favoring alemtuzumab (ATZ) lymphodepleting induction and examined associations with graft function. Fifty-eight recipients were studied: 23 pretransplant and 40 posttransplant (including 5 with pretransplant phenotyping). The proportion with islet-specific T cell responses was not significantly different over time (pre-Tx: 59%; 1-6 m posttransplant: 38%; 7-12 m: 44%; 13-24 m: 47%; and >24 m: 45%). However, phenotype shifted significantly, with IFN-γ-dominated response in the pretransplant group replaced by IL-10-dominated response in the 1-6 m posttransplant group, reverting to predominantly IFN-γ-oriented response in the >24 m group. Clustering analysis of posttransplant responses revealed two main agglomerations, characterized by IFN-γ and IL-10 phenotypes, respectively. IL-10-oriented posttransplant response was associated with relatively low graft function. Recipients within the IL-10+ cluster had a significant decline in C-peptide levels in the period preceding the IL-10 response, but stable graft function following the response. In contrast, an IFN-γ response was associated with subsequently decreased C-peptide. Islet transplantation favoring ATZ induction is associated with an initial altered islet-specific T cell phenotype but reversion toward pretransplant profiles over time. Posttransplant autoreactive T cell phenotype may be a predictor of subsequent graft function.
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Affiliation(s)
- Shereen Sabbah
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, London, UK.,NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
| | - Aaron Liew
- Newcastle University Translational and Clinical Research Institute, Newcastle, UK
| | - Augustin M Brooks
- Newcastle University Translational and Clinical Research Institute, Newcastle, UK
| | - Rhiannon Kundu
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, London, UK.,NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
| | - James L Reading
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, London, UK.,NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
| | - Anneliese Flatt
- Newcastle University Translational and Clinical Research Institute, Newcastle, UK
| | - Claire Counter
- Organ Donation and Transplantation, NHS Blood and Transplant, Bristol, UK
| | - Pratik Choudhary
- Diabetes Research Group, Guy's, King's and St. Thomas' School of Medicine, King's College London, London, UK
| | - Shareen Forbes
- Edinburgh Transplant Centre and Endocrinology Unit, University of Edinburgh, Edinburgh, UK
| | | | - Martin K Rutter
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, School of Medical Sciences, University of Manchester, Manchester, UK.,Diabetes, Endocrinology and Metabolism Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Stephanie Cairns
- Clinical Immunology Department, Scottish National Blood Transfusion Service, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Paul Johnson
- Oxford Centre for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - John Casey
- Edinburgh Transplant Centre and Endocrinology Unit, University of Edinburgh, Edinburgh, UK
| | - Mark Peakman
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, London, UK.,NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
| | - James A Shaw
- Newcastle University Translational and Clinical Research Institute, Newcastle, UK.,Institute of Transplantation, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Timothy I M Tree
- Department of Immunobiology, Faculty of Life Sciences & Medicine, King's College London, London, UK.,NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
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Douthwaite J, Moisan J, Privezentzev C, Soskic B, Sabbah S, Cohen S, Collinson A, England E, Huntington C, Kemp B, Zhuang L, Hudak S, Rees DG, Goldberg D, Barton C, Chang L, Vainshtein I, Liang M, Iciek L, Ambery P, Peakman M, Vaughan TJ, Tree TIM, Sansom DM, Bowen MA, Minter RR, Jermutus L. Correction: A CD80-Biased CTLA4-Ig Fusion Protein with Superior In Vivo Efficacy by Simultaneous Engineering of Affinity, Selectivity, Stability, and FcRn Binding. J I 2017; 199:1943. [DOI: 10.4049/jimmunol.1790013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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3
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Douthwaite J, Moisan J, Privezentzev C, Soskic B, Sabbah S, Cohen S, Collinson A, England E, Huntington C, Kemp B, Zhuang L, Hudak S, Rees DG, Goldberg D, Barton C, Chang L, Vainshtein I, Liang M, Iciek L, Ambery P, Peakman M, Vaughan TJ, Tree TIM, Sansom DM, Bowen MA, Minter RR, Jermutus L. A CD80-Biased CTLA4-Ig Fusion Protein with Superior In Vivo Efficacy by Simultaneous Engineering of Affinity, Selectivity, Stability, and FcRn Binding. J Immunol 2017; 198:528-537. [PMID: 27881707 DOI: 10.4049/jimmunol.1600682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 10/13/2016] [Indexed: 12/16/2022]
Abstract
Affinity- and stability-engineered variants of CTLA4-Ig fusion molecules with enhanced pharmacokinetic profiles could yield improved therapies with the potential of higher efficacy and greater convenience to patients. In this study, to our knowledge, we have, for the first time, used in vitro evolution to simultaneously optimize CTLA4 affinity and stability. We selected for improved binding to both ligands, CD80 and CD86, and screened as dimeric Fc fusions directly in functional assays to identify variants with stronger suppression of in vitro T cell activation. The majority of CTLA4 molecules showing the largest potency gains in primary in vitro and ex vivo human cell assays, using PBMCs from type 1 diabetes patients, had significant improvements in CD80, but only modest gains in CD86 binding. We furthermore observed different potency rankings between our lead molecule MEDI5265, abatacept, and belatacept, depending on which type of APC was used, with MEDI5265 consistently being the most potent. We then created fusions of both stability- and potency-optimized CTLA4 moieties with human Fc variants conferring extended plasma t1/2 In a cynomolgus model of T cell-dependent Ab response, the CTLA4-Ig variant MEDI5265 could be formulated at >100 mg/ml for s.c. administration and showed superior efficacy and significantly prolonged serum t1/2 The combination of higher stability and potency with prolonged pharmacokinetics could be compatible with very infrequent, s.c. dosing while maintaining a similar level of immune suppression to more frequently and i.v. administered licensed therapies.
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Affiliation(s)
| | | | | | - Blagoje Soskic
- Royal Free Campus, Institute of Immunity and Transplantation, University College London, London NW3 2PF, United Kingdom
| | - Shereen Sabbah
- Department of Immunobiology, King's College London, London SE1 9RT, United Kingdom
- Faculty of Life Sciences and Medicine, King's College London, London SE1 9RT, United Kingdom
- National Institutes of Health Research Biomedical Research Centre at Guy's and St. Thomas' National Health Service Foundation Trust, London SE1 9RT, United Kingdom; and
| | | | | | | | | | - Ben Kemp
- MedImmune, Cambridge CB21 6GH, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | - Mark Peakman
- Department of Immunobiology, King's College London, London SE1 9RT, United Kingdom
- Faculty of Life Sciences and Medicine, King's College London, London SE1 9RT, United Kingdom
- National Institutes of Health Research Biomedical Research Centre at Guy's and St. Thomas' National Health Service Foundation Trust, London SE1 9RT, United Kingdom; and
| | | | - Tim I M Tree
- Department of Immunobiology, King's College London, London SE1 9RT, United Kingdom
- Faculty of Life Sciences and Medicine, King's College London, London SE1 9RT, United Kingdom
- National Institutes of Health Research Biomedical Research Centre at Guy's and St. Thomas' National Health Service Foundation Trust, London SE1 9RT, United Kingdom; and
| | - David M Sansom
- Royal Free Campus, Institute of Immunity and Transplantation, University College London, London NW3 2PF, United Kingdom
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Williamson SJ, Nicol SM, Stürzl M, Sabbah S, Hislop AD. Azidothymidine Sensitizes Primary Effusion Lymphoma Cells to Kaposi Sarcoma-Associated Herpesvirus-Specific CD4+ T Cell Control and Inhibits vIRF3 Function. PLoS Pathog 2016; 12:e1006042. [PMID: 27893813 PMCID: PMC5125715 DOI: 10.1371/journal.ppat.1006042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 03/24/2016] [Accepted: 11/04/2016] [Indexed: 01/06/2023] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) is linked with the development of Kaposi sarcoma and the B lymphocyte disorders primary effusion lymphoma (PEL) and multi-centric Castleman disease. T cell immunity limits KSHV infection and disease, however the virus employs multiple mechanisms to inhibit efficient control by these effectors. Thus KSHV-specific CD4+ T cells poorly recognize most PEL cells and even where they can, they are unable to kill them. To make KSHV-infected cells more sensitive to T cell control we treated PEL cells with the thymidine analogue azidothymidine (AZT), which sensitizes PEL lines to Fas-ligand and TRAIL challenge; effector mechanisms which T cells use. PELs co-cultured with KSHV-specific CD4+ T cells in the absence of AZT showed no control of PEL outgrowth. However in the presence of AZT PEL outgrowth was controlled in an MHC-restricted manner. To investigate how AZT sensitizes PELs to immune control we first examined BJAB cells transduced with individual KSHV-latent genes for their ability to resist apoptosis mediated by stimuli delivered through Fas and TRAIL receptors. This showed that in addition to the previously described vFLIP protein, expression of vIRF3 also inhibited apoptosis delivered by these stimuli. Importantly vIRF3 mediated protection from these apoptotic stimuli was inhibited in the presence of AZT as was a second vIRF3 associated phenotype, the downregulation of surface MHC class II. Although both vFLIP and vIRF3 are expressed in PELs, we propose that inhibiting vIRF3 function with AZT may be sufficient to restore T cell control of these tumor cells. Kaposi sarcoma-associated herpesvirus (KSHV) can cause disease in humans in the form of B lymphocyte disorders such as primary effusion lymphoma (PEL) and multicentric Castleman disease. Where tested, these are highly resistant to immune control by KSHV-specific T cells. To investigate how such KSHV-infected cells can be made more sensitive to T cell control we treated PEL lines with azidothymidine (AZT), which has been shown to induce sensitivity in such lines to the mechanisms which T cells use to kill targets. We found this allowed the T cells to control in vitro lymphoma growth. The ability of the T cells to control PEL cell growth was found to correlate with AZT mediated inhibition of function of the KSHV protein vIRF3 which we show has the ability to protect cells from killing by immune effector mechanisms. These studies suggest that the therapeutic drug AZT may be of use to tip the virus host balance away from the virus by interfering with this immune evasion and pro-survival protein, potentially allowing better control by the host.
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Affiliation(s)
- Samantha J. Williamson
- Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Samantha M. Nicol
- Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Michael Stürzl
- Division of Molecular and Experimental Surgery, Department of Surgery, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Shereen Sabbah
- Department of Immunobiology, King's College London, London, United Kingdom
| | - Andrew D. Hislop
- Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail:
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Nicol SM, Sabbah S, Brulois KF, Jung JU, Bell AI, Hislop AD. Primary B Lymphocytes Infected with Kaposi's Sarcoma-Associated Herpesvirus Can Be Expanded In Vitro and Are Recognized by LANA-Specific CD4+ T Cells. J Virol 2016; 90:3849-3859. [PMID: 26819313 PMCID: PMC4810529 DOI: 10.1128/jvi.02377-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [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: 09/15/2015] [Accepted: 01/20/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Kaposi's sarcoma-associated herpesvirus (KSHV) has tropism for B lymphocytes, in which it establishes latency, and can also cause lymphoproliferative disorders of these cells manifesting as primary effusion lymphoma (PEL) and multicentric Castleman disease (MCD). T cell immunity is vital for the control of KSHV infection and disease; however, few models of B lymphocyte infection exist to study immune recognition of such cells. Here, we developed a model of B lymphocyte infection with KSHV in which infected tonsillar B lymphocytes were expanded by providing mitogenic stimuli and then challenged with KSHV-specific CD4(+)T cells. The infected cells expressed viral proteins found in PELs, namely, LANA and viral IRF3 (vIRF3), albeit at lower levels, with similar patterns of gene expression for the major latency, viral interleukin 6 (vIL-6), and vIRF3 transcripts. Despite low-level expression of open reading frame 50 (ORF50), transcripts for the immune evasion genes K3 and K5 were detected, with some downregulation of cell surface-expressed CD86 and ICAM. The vast majority of infected lymphocytes expressed IgM heavy chains with Igλ light chains, recapitulating the features seen in infected cells in MCD. We assessed the ability of the infected lymphocytes to be targeted by a panel of major histocompatibility complex (MHC) class II-matched CD4(+)T cells and found that LANA-specific T cells restricted to different epitopes recognized these infected cells. Given that at least some KSHV latent antigens are thought to be poor targets for CD8(+)T cells, we suggest that CD4(+)T cells are potentially important effectors for thein vivocontrol of KSHV-infected B lymphocytes. IMPORTANCE KSHV establishes a latent reservoir within B lymphocytes, but few models exist to study KSHV-infected B cells other than the transformed PEL cell lines, which have likely accrued mutations during the transformation process. We developed a model of KSHV-infected primary B lymphocytes that recapitulates features seen in PEL and MCD by gene expression and cell phenotype analysis, allowing the study of T cell recognition of these cells. Challenge of KSHV-infected B cells with CD4(+)T cells specific for LANA, a protein expressed in all KSHV-infected cells and malignanciesin vivo, showed that these effectors could efficiently recognize such targets. Given that the virus expresses immune evasion genes or uses proteins with intrinsic properties, such as LANA, that minimize epitope recognition by CD8(+)T cells, CD4(+)T cell immunity to KSHV may be important for maintaining the virus-host balance.
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Affiliation(s)
- Samantha M Nicol
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Shereen Sabbah
- Department of Immunobiology, King's College London, London, United Kingdom
| | - Kevin F Brulois
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Jae U Jung
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Andrew I Bell
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Andrew D Hislop
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
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Reading JL, Vaes B, Hull C, Sabbah S, Hayday T, Wang NS, DiPiero A, Lehman NA, Taggart JM, Carty F, English K, Pinxteren J, Deans R, Ting AE, Tree TIM. Suppression of IL-7-dependent Effector T-cell Expansion by Multipotent Adult Progenitor Cells and PGE2. Mol Ther 2015. [PMID: 26216515 DOI: 10.1038/mt.2015.131] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
T-cell depletion therapy is used to prevent acute allograft rejection, treat autoimmunity and create space for bone marrow or hematopoietic cell transplantation. The evolved response to T-cell loss is a transient increase in IL-7 that drives compensatory homeostatic proliferation (HP) of mature T cells. Paradoxically, the exaggerated form of this process that occurs following lymphodepletion expands effector T-cells, often causing loss of immunological tolerance that results in rapid graft rejection, autoimmunity, and exacerbated graft-versus-host disease (GVHD). While standard immune suppression is unable to treat these pathologies, growing evidence suggests that manipulating the incipient process of HP increases allograft survival, prevents autoimmunity, and markedly reduces GVHD. Multipotent adult progenitor cells (MAPC) are a clinical grade immunomodulatory cell therapy known to alter γ-chain cytokine responses in T-cells. Herein, we demonstrate that MAPC regulate HP of human T-cells, prevent the expansion of Th1, Th17, and Th22 effectors, and block the development of pathogenic allograft responses. This occurs via IL-1β-primed secretion of PGE2 and activates T-cell intrinsic regulatory mechanisms (SOCS2, GADD45A). These data provide proof-of-principle that HP of human T-cells can be targeted by cellular and molecular therapies and lays a basis for the development of novel strategies to prevent immunopathology in lymphodepleted patients.
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Affiliation(s)
- James L Reading
- Department of Immunobiology, King's College London, London, UK.
| | | | - Caroline Hull
- Department of Immunobiology, King's College London, London, UK
| | - Shereen Sabbah
- Department of Immunobiology, King's College London, London, UK
| | - Thomas Hayday
- Department of Immunobiology, King's College London, London, UK
| | | | | | | | | | - Fiona Carty
- Department of Biology, Institute of Immunology, National University of Ireland, Maynooth, Ireland
| | - Karen English
- Department of Biology, Institute of Immunology, National University of Ireland, Maynooth, Ireland
| | | | | | | | - Timothy I M Tree
- Department of Immunobiology, King's College London, London, UK; NIHR Biomedical Research Centre at Guy's & St Thomas' NHS Foundation Trust and King's College London, London, UK
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Long HM, Chagoury OL, Leese AM, Ryan GB, James E, Morton LT, Abbott RJM, Sabbah S, Kwok W, Rickinson AB. MHC II tetramers visualize human CD4+ T cell responses to Epstein-Barr virus infection and demonstrate atypical kinetics of the nuclear antigen EBNA1 response. ACTA ACUST UNITED AC 2013; 210:933-49. [PMID: 23569328 PMCID: PMC3646497 DOI: 10.1084/jem.20121437] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Characterization of the human EBV-specific CD4+ T cell response using MHC II tetramers reveals the latent EBV antigen response is more frequent than the lytic response with a delayed EBNA1 response that coincides with diminished cross-presentation. Virus-specific CD4+ T cells are key orchestrators of host responses to viral infection yet, compared with their CD8+ T cell counterparts, remain poorly characterized at the single cell level. Here we use nine MHC II–epitope peptide tetramers to visualize human CD4+ T cell responses to Epstein–Barr virus (EBV), the causative agent of infectious mononucleosis (IM), a disease associated with large virus-specific CD8+ T cell responses. We find that, while not approaching virus-specific CD8+ T cell expansions in magnitude, activated CD4+ T cells specific for epitopes in the latent antigen EBNA2 and four lytic cycle antigens are detected at high frequencies in acute IM blood. They then fall rapidly to values typical of life-long virus carriage where most tetramer-positive cells display conventional memory markers but some, unexpectedly, revert to a naive-like phenotype. In contrast CD4+ T cell responses to EBNA1 epitopes are greatly delayed in IM patients, in line with the well-known but hitherto unexplained delay in EBNA1 IgG antibody responses. We present evidence from an in vitro system that may explain these unusual kinetics. Unlike other EBNAs and lytic cycle proteins, EBNA1 is not naturally released from EBV-infected cells as a source of antigen for CD4+ T cell priming.
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Affiliation(s)
- Heather M Long
- School of Cancer Sciences and MRC Centre for Immune Regulation, College of Medicine, University of Birmingham, B15 2TT Birmingham, England, UK
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Reading JL, Yang JHM, Sabbah S, Skowera A, Knight RR, Pinxteren J, Vaes B, Allsopp T, Ting AE, Busch S, Raber A, Deans R, Tree TIM. Clinical-Grade Multipotent Adult Progenitor Cells Durably Control Pathogenic T Cell Responses in Human Models of Transplantation and Autoimmunity. J I 2013; 190:4542-52. [DOI: 10.4049/jimmunol.1202710] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Hawryshyn CW, Ramsden SD, Betke KM, Sabbah S. Spectral and polarization sensitivity of juvenile Atlantic salmon (Salmo salar): phylogenetic considerations. ACTA ACUST UNITED AC 2010; 213:3187-97. [PMID: 20802121 DOI: 10.1242/jeb.038760] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We were interested in comparing the characteristics of polarization sensitivity in Atlantic salmon to those in Pacific salmon. Here we show that the common ancestor to the clade containing Salmo salar, Oncorhynchus mykiss, O. nerka, O. clarkii and Salvelinus fontinalis has the trait of ultraviolet polarization sensitivity. We examined spectral and polarization sensitivity of juvenile Atlantic salmon (Salmo salar) using both optic nerve compound action potential (CAP) and electroretinogram (ERG) recordings. Our experiments employed photic manipulation to adjust the sensitivity of the four cone mechanisms of Atlantic salmon. A spectrally broad background was used to ensure a contribution of all cone mechanisms to both spectral and polarization sensitivity. Chromatic adaptation was used to isolate the sensitivity of each of the four cone mechanisms for both spectral and polarization sensitivity. Under spectrally broad conditions, UV sensitive (UVS), mid wavelength sensitive (MWS) and long wavelength sensitive (LWS) cone mechanisms contributed to polarization sensitivity. CAP recordings produced the typical 'W' shaped polarization sensitivity curve reflecting two active polarization detectors with peaks at e-vector orientations of 0 deg, 90 deg and 180 deg, and troughs at 30 deg and 150 deg. ERG recordings produced a four-peaked polarization sensitivity curve reflecting two active polarization detectors and negative feedback activity, with peaks at e-vectors 0 deg, 45 deg, 90 deg, 135 deg and 180 deg, and troughs at 30 deg, 60 deg, 120 deg and 150 deg. Polarization-sensitivity measurements of isolated cone mechanisms revealed two orthogonal polarization detector mechanisms in Atlantic salmon, identical to that found in rainbow trout and other Pacific salmonid fishes. Moreover, under spectrally broad background conditions, CAP and ERG polarization sensitivity of Atlantic salmon did not differ significantly from that reported in Pacific salmonids.
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Affiliation(s)
- C W Hawryshyn
- Department of Biology and Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada K7L 3N6
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Abstract
The desert locust Schistocerca gregaria is a well known migrating insect, travelling long distances in swarms containing millions of individuals. During November 2004, such a locust swarm reached the northern coast of the Gulf of Aqaba, coming from the Sinai desert towards the southeast. Upon reaching the coast, they avoided flying over the water, and instead flew north along the coast. Only after passing the tip of the gulf did they turn east again. Experiments with tethered locusts showed that they avoided flying over a light-reflecting mirror, and when given a choice of a non-polarizing reflecting surface and a surface that reflected linearly polarized light, they preferred to fly over the former. Our results suggest that locusts can detect the polarized reflections of bodies of water and avoid crossing them; at least when flying at low altitudes, they can therefore avoid flying over these dangerous areas.
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Affiliation(s)
- N Shashar
- H. Steinitz Marine Biology Laboratory, The Interuniversity Institute of Eilat, PO Box 469, 88103 Eilat, Israel.
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Dridi S, Driss MR, Sabbah S, Bouguerra ML. Determination of Polycyclic Aromatic Hydrocarbons in Airborne Diesel Exhaust Particulates by HPLC with UV Detection and Wavelength Programming. J LIQ CHROMATOGR R T 2006. [DOI: 10.1080/10826079808001234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- S. Dridi
- a Département de Chimie , Faculté des Sciences de Tunis Le Belvédère , 1060, Tunis, Tunisia
| | - M. R. Driss
- b Département de Chimie , Faculté des Sciences de Bizerte , 7021, Zarzouna, Tunisia
| | - S. Sabbah
- a Département de Chimie , Faculté des Sciences de Tunis Le Belvédère , 1060, Tunis, Tunisia
| | - M. L. Bouguerra
- a Département de Chimie , Faculté des Sciences de Tunis Le Belvédère , 1060, Tunis, Tunisia
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Abstract
The angiotensin converting enzyme inhibitor, enalaprilat can exist in solution as cis and trans conformers which interconvert around the amide bond at room temperature. A HPLC with UV detection was performed to study the influence of various chromatographic operational conditions on both rotamers separation and elution of enalaprilat as a single peak. In addition nuclear overhauser enhancement difference was used for the identification of the conformers. The isomer ratio integrated from the obtained 1H NMR result were 71.5:28.5 and 76:24 at 298 and 279 K, respectively where the trans was the major form.
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Affiliation(s)
- S Bouabdallah
- Laboratoire National de Contrôle des Médicaments 11bis, rue jebel Lakhdar, Bab Saadoun 1006, Tunis, Tunisia
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Abstract
The effect of flow rate, temperature, pH, organic solvent and counter ion on peak shape and separation of the cis and trans conformers of lisinopril are investigated by HPLC. It was demonstrated that complete separation of the two isomers can be achieved at low temperature at either neutral or low pH together with appropriate type and concentration of organic solvent, whereas the elution of lisinopril as a single peak is favored by a decrease of flow rate, elevated temperature, choice of organic solvent (type and amount) and the use of an appropriate counter ion concentration.
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Affiliation(s)
- S Bouabdallah
- Laboratoire National de Contrôle des Médicaments 11 bis, rue jebel Lakhdar, Bab Saadoun, 1006 Tunis, Tunisia
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Louka YL, Sabbah S, Scriba GK. Method development and validation for the chiral separation of peptides in the presence of cyclodextrins using capillary electrophoresis and experimental design. J Chromatogr A 2001; 931:141-52. [PMID: 11695516 DOI: 10.1016/s0021-9673(01)01179-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The present study describes the application of statistical experimental design to the optimization of enantioselective separations of peptides in capillary electrophoresis in order to obtain optimal operating conditions for routine work. Hydroxypropyl-beta-cyclodextrin was used as chiral selector and Ala-PheOMe as model peptide. The experiments were performed according to a face centered cube response surface experimental design for obtaining information how the factors such as concentration of the chiral selector, pH, buffer concentration and voltage affected the two response goals, resolution and analysis time. In order to achieve the simultaneous optimization of these two major electrophoretic performance goals for efficient and fast separation, the Derringer desirability functions were tested. While in the predefined experiments the analysis time for baseline separation was 25 min the desirability functions proposed a CE method, which diminished the analysis time and permitted the complete separation of the peptide enantiomers within 9 min.
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Affiliation(s)
- Y L Louka
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Athens, Greece.
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15
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Abstract
The chiral separation of the LL- and DD-enantiomers of the dipeptides Ala-Tyr, Phe-Phe, and Asp-PheOMe has been investigated at pH 2.5 and pH 3.5 using beta-cyclodextrin (beta-CD), heptakis-(2,6-di-O-methyl)-beta-cyclodextrin, and heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin as chiral selectors. According to electrospray mass spectrometry, heptakis-(2,6-di-O-methyl)-beta-cyclodextrin was a mixture of six isomers. Reversal of the enantiomer migration order upon increasing the buffer pH from 2.5 to 3.5 was observed for all peptides with beta-cyclodextrin, for Ala-Tyr and Phe-Phe in the presence of heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin, and for Ala-Tyr using heptakis-(2,6-di-O-methyl)-beta-cyclodextrin. The migration behavior could be explained on the basis of the complexation constants and the mobilities of the peptide-cyclodextrin complexes. Both, the binding constants and complex mobilities decreased with increasing pH as the overall-charge of the peptides decreased. While the complexation constants primarily determined the migration order at pH 2.5, complex mobility dominated in most cases at pH 3.5.
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Affiliation(s)
- S Sabbah
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Jena, Germany
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Sabbah S, Abu-Khurmah M, Oelschläger H, Scriba GKE. Analysis of aminopyridines and diaminopyridines by capillary electrophoresis. Chromatographia 2001. [DOI: 10.1007/bf02491623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Sabbah S, Scriba GK. Separation of dipeptide and tripeptide enantiomers in capillary electrophoresis using carboxymethyl-beta-cyclodextrin and succinyl-beta-cyclodextrin: influence of the amino acid sequence, nature of the cyclodextrin and pH. Electrophoresis 2001; 22:1385-93. [PMID: 11379961 DOI: 10.1002/1522-2683(200105)22:7<1385::aid-elps1385>3.0.co;2-a] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The separation of the LL and DD enantiomers of dipeptides and tripeptides using cyclodextrins (CDs) containing carboxyl groups was investigated with respect to the amino acid sequence of the peptides, the nature of the cyclodextrin and the buffer pH. Compared to succinyl-beta-cyclodextrin, carboxymethyl-beta-cyclodextrin was the more universal CD for enantioseparations. Reversal of the enantiomer migration order upon increasing the buffer pH from 2.5 to 3.5 was observed in some cases. As shown for Phe-Phe reversal of the migration order also occurred between pH 3.5 and 5.3. Complexation constants and complex mobilities change with pH as both, the charge of the peptide and the charge of the CD vary depending on the pH. The complexation constants and complex mobilities of the dipeptides Ala-Phe and Phe-Phe were determined in order to explain the enantiomer migration behavior in the pH range 2.5-5.3. While the complexation constants determined the migration order at pH 2.5 and 5.3, complex mobility had a strong influence around pH 3.5-3.8.
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Affiliation(s)
- S Sabbah
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Jena, Germany
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Abstract
A capillary electrophoresis assay for the analysis of aminopyridines and diaminopyridines has been developed and validated. The compounds were separated using a 100 mM sodium acetate buffer at pH 5.15, an applied voltage of 20 kV and a capillary of 60 cm effective length, N-(1-naphthyl)ethylenediamine was used as internal standard to compensate for injection errors and minor fluctuations of the migration times. The detection wavelength was set at 240 nm and not optimized for a specific derivative. The assay was validated with respect to specificity, linearity, range, limit of quantitation and detection, precision, and robustness. Within certain limits, the assay also allowed the detection and determination of the other aminopyridine derivatives at the 0.1% level as demonstrated for 3,4-diaminopyridine.
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Affiliation(s)
- S Sabbah
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Jena, Germany
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Sabbah S, Scriba GK. Development and validation of a capillary electrophoresis assay for the determination of 3,4-diaminopyridine and 4-aminopyridine including related substances. J Chromatogr A 2001; 907:321-8. [PMID: 11217039 DOI: 10.1016/s0021-9673(00)01067-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A capillary electrophoresis (CE) assay has been developed for the quantitation and determination of the impurity profile of the potassium channel blockers 3,4-diaminopyridine and 4-aminopyridine. The compounds were separated from related substances using a capillary of 30 cm effective length, a 50 mM phosphate buffer, pH 2.5 and an applied voltage of 25 kV. The assay was validated with respect to specificity, linearity, range, limits of quantitation and detection, precision and robustness. The method allows the detection and quantitation of impurities at the 0.05% level. The feasibility of the assay was demonstrated by analyzing a commercial sample of 3,4-diaminopyridine. All known related substances could be detected in this sample with the present CE method.
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Affiliation(s)
- S Sabbah
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Jena, Germany
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Sabbah S, Scriba GK. Influence of the structure of cyclodextrins and amino acid sequence of dipeptides and tripeptides on the pH-dependent reversal of the migration order in capillary electrophoresis. J Chromatogr A 2000; 894:267-72. [PMID: 11100869 DOI: 10.1016/s0021-9673(00)00527-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [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: 11/24/2022]
Abstract
The pH-dependent reversal of the migration order in cyclodextrin (CD)-mediated capillary electrophoresis (CE) enantioseparations of dipeptides and tripeptides has been studied between pH 2.5 and 3.5 using beta-CD and several of its neutral derivatives. The occurrence of the phenomenon depended on both the structure of the CD and the amino acid composition and sequence of the peptides. While an inversion was observed for several peptides when native beta-CD, dimethyl-beta-cyclodextrin or trimethyl-beta-cyclodextrin were added to the run buffer, no alteration of the order occurred in the presence of permethyl-beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin. Most peptides that displayed a change of the migration behavior upon increasing the buffer pH contained Phe at the C-terminus. An ionizable carboxyl group in the peptide structure was a prerequisite. As seen with other uncommon migration effects in CE, the pH-dependent reversal of the migration order occurred in the pH region of the pKa values of the peptide carboxyl functions.
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Affiliation(s)
- S Sabbah
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Jena, Germany
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Trabelsi H, Bouabdallah S, Sabbah S, Raouafi F, Bouzouita K. Study of the cis-trans isomerization of enalapril by reversed-phase liquid chromatography. J Chromatogr A 2000; 871:189-99. [PMID: 10735299 DOI: 10.1016/s0021-9673(99)01214-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Enalapril is a dipeptidic angiotensin converting enzyme inhibitor. It exists as a mixture of two conformers in solution with respect to the peptide bond involving the proline amino group. The RPLC of such products may yield peak splitting or multiple peaks as a result of the slow kinetics of the conformation change. In this study, the influence of the flow-rate, pH, temperature, organic modifier and counter ion on the peak shape and the separation of the cis and trans conformers are examined qualitatively by HPLC. It appears that decrease of relaxation time for isomerization with concomitant improvement in peak shape is favoured by a decrease in pH and flow-rate, increase of temperature, choice of organic solvent (nature, amount) and cationic counter ion concentration in the mobile phase. The elution order of the isomers was dependent on the nature of the organic modifier whereas the separation selectivity was improved by an increase of pH or the addition of a negatively charged counter ion. In addition, an NMR investigation on enalapril is described.
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Affiliation(s)
- H Trabelsi
- Laboratoire National de contrôle des Médicaments, Bab Saadoun, Tunis, Tunisia.
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Sabbah S, Raise M, Tal M. Methylation of DNA in NaCl-adapted cells of potato. Plant Cell Rep 1995; 14:467-70. [PMID: 24185459 DOI: 10.1007/bf00234057] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/1994] [Revised: 10/10/1994] [Indexed: 05/25/2023]
Abstract
Salt-adapted and control cells of the cultivated potato, Solanum tuberosum cultivar Russet Burbank, untreated or treated with 5-azacytidine (an inhibitor of DNA methylation), were compared with respect to: a) % of cytosine methylation in total nuclear DNA, as determined by HPLC; b) fresh and dry weight. Adapted and control cells were compared also with respect to % of cytosine methylation in DNA, which was purified from DNaseI-partially-digested chromatin and size fractionated by electrophoresis in agarose gels. The growth (represented by dry weight) of the NaCl-adapted cells in saline medium lacking 5-azacytidine was similar to that of control cells in standard medium. The adaptation of the cells was correlated with some increase (+16%) of methylation in total DNA and with a much greater increase in the lower molecular weight DNA fractions which were obtained from the presumably more active chromatin. As expected, the treatment of the cells with the methylation inhibitor induced a decrease in the level of methylation. The decrease of methylation, however, was much greater in the adapted cells, whose dry weight, unlike in the control, was not affected by this treatment.
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Affiliation(s)
- S Sabbah
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 84105, Beer Sheva, Israel
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Gurbindo C, Sabbah S, Menezes J, Justinich C, Marchand R, Seidman EG. Interleukin-2 production in pediatric inflammatory bowel disease: evidence for dissimilar mononuclear cell function in Crohn's disease and ulcerative colitis. J Pediatr Gastroenterol Nutr 1993; 17:247-54. [PMID: 8271122 DOI: 10.1097/00005176-199310000-00003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Crohn's disease (CD) and ulcerative colitis (UC) represent clinically distinct chronic inflammatory bowel diseases (IBD) of unknown etiology. Although the mucosal immune system is implicated in their pathogenesis, immunological differences between the two disorders are not well defined. The aim of this study was to compare in vitro mucosal T-lymphocyte function in CD and UC. Peripheral blood mononuclear cell interleukin-2 (IL-2) production was similar in pediatric IBD and control patients under unstimulated conditions, but was significantly increased in response to phytohemagglutinin (PHA) stimulation for the UC group. Lamina propria mononuclear cells (LPMNC) isolated from colonic resections in IBD patients had significantly lower spontaneous proliferation and IL-2 production in vitro than did LPMNC of control patients. In contrast, significantly greater IL-2 production was detected when the LPMNC of CD patients were cultured with PHA, in comparison with those of UC or control patients. When indomethacin, a prostaglandin synthetase inhibitor, was added to the cultures, significantly increased IL-2 secretion was observed for CD LPMNC, but not for UC cultures, under both stimulated and unstimulated conditions. These findings demonstrate abnormal LPMNC IL-2 production in IBD. Furthermore, our data suggest that inhibition of the prostaglandin synthetase pathway upregulates IL-2 production by LPMNC in CD. These results support the hypothesis that immunoregulatory mechanisms controlling IL-2 production differ between CD and UC.
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Affiliation(s)
- C Gurbindo
- Intestinal Immunology Laboratory, Ste-Justine Hospital, Montreal, Quebec, Canada
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Abstract
BACKGROUND Altered interleukin 2 (IL-2) production has been implicated in the pathogenesis of inflammatory bowel diseases. METHODS The temporal relationship between IL-2, prostaglandin E2 (PGE2) production, and mucosal injury was evaluated by isolated colonic lamina propria mononuclear cells (LPMC), using the trinitrobenzene sulfonic acid model of rat colitis. RESULTS Spontaneous LPMC IL-2 activity was significantly increased in chronic (5 weeks) but not acute (5 days) or resolved colitis groups. IL-2 activity after concanavalin A activation was highest in the groups with resolved and chronic colitis. PGE2 production was significantly increased in LPMC cultures in acute or chronic colitis as well as the ethanol control groups but not the resolved colitis group. The addition of indomethacin to LPMC cultures decreased PGE2 levels in all groups, whereas IL-2 activity increased only for the chronic and resolved colitis groups. No correlation was found between PGE2 and IL-2 production by LPMC. CONCLUSIONS In this experimental model, LPMC IL-2 production varied according to the severity and duration of the inflammation. Increased PGE2 production does not appear to be responsible for the IL-2 alterations in colitis.
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Affiliation(s)
- C Gurbindo
- Division of Pediatric Gastroenterology, Hopital Ste. Justine, Montreal, Quebec, Canada
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Driss MR, Sabbah S, Bouguerra ML. [High resolution gas phase chromatography-mass spectrometry of polychlorinated biphenyl congener residues in samples of biologic origin]. J Chromatogr A 1991; 552:213-22. [PMID: 1939437 DOI: 10.1016/s0021-9673(01)95936-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A study is performed on polychlorinated biphenyl (PCB) congener residues in samples of human blood and milk as well as in falcon and pigeon eggs. Most of the PCB congeners found in these biological samples were quantified by high-resolution gas chromatography (HRGC). A PCB technical mixture--namely, DP6 (Phenochlor)--was used for the calibration as its composition was previously determined by HRGC-mass spectrometry. The usefulness of such a congener analysis is outlined. It is the first time to the best of our knowledge that a Phenochlor mixture is used for standardization.
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Affiliation(s)
- M R Driss
- Département de Chimie, Faculté des Sciences, Campus Universitaire le Belvédère, Tunis, Tunisie
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