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Quartermain MD, Glatz AC, Goldberg DJ, Cohen MS, Elias MD, Tian Z, Rychik J. Pulmonary outflow tract obstruction in fetuses with complex congenital heart disease: predicting the need for neonatal intervention. Ultrasound Obstet Gynecol 2013; 41:47-53. [PMID: 22605656 DOI: 10.1002/uog.11196] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/02/2012] [Indexed: 05/31/2023]
Abstract
OBJECTIVE To identify prenatal echocardiographic markers that could predict the need for neonatal intervention in fetuses with right ventricular outflow tract obstruction. METHODS This was a retrospective study of 52 fetuses with right ventricular outflow tract obstruction. Echocardiograms were evaluated for fetuses with either two-ventricle anatomy with a large ventricular septal defect or single-ventricle anatomy. Fetuses with pulmonary atresia were excluded. Parameters were compared between groups that did and did not require an intervention at age < 30 days. RESULTS Fifty-two fetuses were studied; 20 (38%) underwent neonatal intervention and 32 (62%) did not. The most common diagnosis was tetralogy of Fallot (n = 32). Fetuses with two ventricles that required an intervention had lower pulmonary valve diameter Z-score (PV-Z-score) (-4.8 ± 2.1 vs. -2.6 ± 1.1; P = 0.0002) and lower pulmonary valve to aortic valve annular diameter ratio (PV/AoV) (0.53 ± 0.15 vs. 0.66 ± 0.1; P = 0.003). Using a PV/AoV ratio of < 0.6 or a PV-Z-score of < -3 at final echocardiographic examination was highly sensitive (92%) but poorly specific (50%), whereas classifying direction of flow in the ductus arteriosus as either normal (all pulmonary-to-aorta) or abnormal (aorta-to-pulmonary or bidirectional) was both highly sensitive (100%) and specific (95%) for predicting the need for a neonatal intervention. Parameters for the single-ventricle cohort did not reach statistical significance. CONCLUSIONS Analysis of the pulmonary outflow tract and ductus arteriosus flow in the fetus with complex congenital heart disease can aid in identifying those that will require a neonatal intervention to augment pulmonary blood flow. This has important implications for the planning of delivery strategies.
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Affiliation(s)
- M D Quartermain
- Fetal Heart Program at the Cardiac Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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Corbett CR, Ballegeer E, Weedmark KA, Elias MD, Al-Saleem FH, Ancharski DM, Simpson LL, Berry JD. Epitope characterization of sero-specific monoclonal antibody to Clostridium botulinum neurotoxin type A. Hybridoma (Larchmt) 2012; 30:503-10. [PMID: 22149274 DOI: 10.1089/hyb.2011.0032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Botulinum neurotoxins (BoNTs) are extremely potent toxins that can contaminate foods and are a public health concern. Anti-BoNT antibodies have been described that are capable of detecting BoNTs; however there still exists a need for accurate and sensitive detection capabilities for BoNTs. Herein, we describe the characterization of a panel of eight monoclonal antibodies (MAbs) generated to the non-toxic receptor-binding domain of BoNT/A (H(C)50/A) developed using a high-throughput screening approach. In two independent hybridoma fusions, two groups of four IgG MAbs were developed against recombinant H(C)50/A. Of these eight, only a single MAb, F90G5-3, bound to the whole BoNT/A protein and was characterized further. The F90G5-3 MAb slightly prolonged time to death in an in vivo mouse bioassay and was mapped by pepscan to a peptide epitope in the N-terminal subdomain of H(C)50/A (H(CN)25/A) comprising amino acid residues (985)WTLQDTQEIKQRVVF(999), an epitope that is highly immunoreactive in humans. Furthermore, we demonstrate that F90G5-3 binds BoNT/A with nanomolar efficiency. Together, our results indicate that F90G5-3 is of potential value as a diagnostic immunoreagent for BoNT/A capture assay development and bio-forensic analysis.
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Affiliation(s)
- Cindi R Corbett
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Mannitoba, Canada.
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Adekar SP, Segan AT, Chen C, Bermudez R, Elias MD, Selling BH, Kapadnis BP, Simpson LL, Simon PM, Dessain SK. Enhanced neutralization potency of botulinum neurotoxin antibodies using a red blood cell-targeting fusion protein. PLoS One 2011; 6:e17491. [PMID: 21399689 PMCID: PMC3047547 DOI: 10.1371/journal.pone.0017491] [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 02/03/2011] [Indexed: 01/17/2023] Open
Abstract
Botulinum neurotoxin (BoNT) potently inhibits cholinergic signaling at the neuromuscular junction. The ideal countermeasures for BoNT exposure are monoclonal antibodies or BoNT antisera, which form BoNT-containing immune complexes that are rapidly cleared from the general circulation. Clearance of opsonized toxins may involve complement receptor-mediated immunoadherence to red blood cells (RBC) in primates or to platelets in rodents. Methods of enhancing immunoadherence of BoNT-specific antibodies may increase their potency in vivo. We designed a novel fusion protein (FP) to link biotinylated molecules to glycophorin A (GPA) on the RBC surface. The FP consists of an scFv specific for murine GPA fused to streptavidin. FP:mAb:BoNT complexes bound specifically to the RBC surface in vitro. In a mouse model of BoNT neutralization, the FP increased the potency of single and double antibody combinations in BoNT neutralization. A combination of two antibodies with the FP gave complete neutralization of 5,000 LD50 BoNT in mice. Neutralization in vivo was dependent on biotinylation of both antibodies and correlated with a reduction of plasma BoNT levels. In a post-exposure model of intoxication, FP:mAb complexes gave complete protection from a lethal BoNT/A1 dose when administered within 2 hours of toxin exposure. In a pre-exposure prophylaxis model, mice were fully protected for 72 hours following administration of the FP:mAb complex. These results demonstrate that RBC-targeted immunoadherence through the FP is a potent enhancer of BoNT neutralization by antibodies in vivo.
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Affiliation(s)
- Sharad P. Adekar
- Lankenau Institute for Medical Research,
Wynnewood, Pennsylvania, United States of America
- Immunome, Inc., Wynnewood, Pennsylvania,
United States of America
- Augmenta Biologicals, LLC, Wynnewood,
Pennsylvania, United States of America
| | - Andrew T. Segan
- Lankenau Institute for Medical Research,
Wynnewood, Pennsylvania, United States of America
| | - Cindy Chen
- Lankenau Institute for Medical Research,
Wynnewood, Pennsylvania, United States of America
| | - Rodney Bermudez
- Immunome, Inc., Wynnewood, Pennsylvania,
United States of America
| | - M. D. Elias
- Division of Infectious Diseases and
Environmental Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania,
United States of America
| | - Bernard H. Selling
- Impact Biologicals, Inc. Wallingford,
Pennsylvania, United States of America
| | - B. P. Kapadnis
- Department of Microbiology, University of
Pune, Pune, India
| | - Lance L. Simpson
- Division of Infectious Diseases and
Environmental Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania,
United States of America
| | - Paul M. Simon
- Augmenta Biologicals, LLC, Wynnewood,
Pennsylvania, United States of America
- * E-mail: (SKD); (PMS)
| | - Scott K. Dessain
- Lankenau Institute for Medical Research,
Wynnewood, Pennsylvania, United States of America
- * E-mail: (SKD); (PMS)
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Adekar SP, Al-Saleem FH, Elias MD, Rybinski KA, Simpson LL, Dessain SK. A natural human IgM antibody that neutralizes botulinum neurotoxin in vivo. Hybridoma (Larchmt) 2008; 27:65-9. [PMID: 18642670 DOI: 10.1089/hyb.2007.0549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Affinity-matured human antibodies have demonstrated efficacy as countermeasures for exposure to botulinum neurotoxin (BoNT), which is the cause of the disease botulism category A select bioterror agent. Little is known, however, about the potential role of natural (un-mutated) antibodies in the protective immune response to BoNT. Here we describe the cloning of two human IgM antibodies that bind serotype A BoNT. Both are un-mutated IgM antibodies, consistent with an origin in naive B cells. One of the antibodies is able to fully neutralize a lethal dose of serotype A BoNT in vivo. These results suggest that the natural human antibody repertoire may play a role in protection from exposure to biological toxins.
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Affiliation(s)
- Sharad P Adekar
- Cardeza Foundation for Hematologic Research and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Adekar SP, Jones RM, Elias MD, Al-Saleem FH, Root MJ, Simpson LL, Dessain SK. A human monoclonal antibody that binds serotype A botulinum neurotoxin. Hybridoma (Larchmt) 2008; 27:11-7. [PMID: 18294071 DOI: 10.1089/hyb.2007.0536] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Monoclonal antibodies have demonstrated significant potential as therapeutics for botulinum neurotoxin exposures. We previously described a hybridoma method for cloning native human antibodies that uses a murine myeloma cell line that ectopically expresses the human telomerase catalytic subunit gene (hTERT) and the murine interleukin-6 gene (mIL-6). Here we describe a heterohybridoma cell line that ectopically expresses mIL-6 and hTERT and has improved stability of hTERT expression. We fused this cell line to human peripheral blood B cells from a subject who had received the botulinum toxoid vaccine, cloning a high-affinity antibody (13A) specific for serotype A botulinum neurotoxin (BoNT/A). The 13A antibody is an affinity-matured, post-germinal center IgG(1) lambda antibody that has partial neutralization activity in vivo. 13A binds an epitope on BoNT/A that overlaps the binding epitope of an IgG antibody previously shown to fully neutralize a lethal dose of BoNT/A in vivo. The 13A antibody may be useful for diagnostic testing or for incorporation into an oligoclonal therapeutic to counteract BoNT/A exposure.
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Affiliation(s)
- Sharad P Adekar
- Cardeza Foundation for Hematologic Research and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Adekar SP, Jones RM, Elias MD, Al-Saleem FH, Root MJ, Simpson LL, Dessain SK. Hybridoma populations enriched for affinity-matured human IgGs yield high-affinity antibodies specific for botulinum neurotoxins. J Immunol Methods 2008; 333:156-66. [PMID: 18313069 DOI: 10.1016/j.jim.2008.01.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 12/17/2007] [Accepted: 01/24/2008] [Indexed: 01/26/2023]
Abstract
The affinity-matured human antibody repertoire may be ideal as a source for antibody therapeutics against infectious diseases and bioterror agents. Hybridoma methods for cloning these antibodies have many potential advantages, including convenience, high-yield antibody expression, and the ability to capture the antibodies in their native configurations. However, they have been hindered by hybridoma instability and limited accessibility of antigen-specific, class-switched human B-cells. Here, we describe an efficient, three-step method that uses human peripheral blood B-cells to produce stable hybridoma populations that are highly-enriched for affinity-matured human IgG antibodies. Peripheral blood mononuclear cells (PBMCs) are (a) selected for expression of CD27, a marker of post-germinal center B-cells, (b) cultured in vitro to promote B-cell proliferation and class-switching, and (c) fused to a genetically modified myeloma cell line. Using this strategy, we cloned 5 IgG antibodies that bind botulinum neurotoxins (BoNT), the causes of the food-borne paralytic illness, botulism, and Category A Select Bioterror agents. Two of these antibodies bind BoNT with low picomolar affinities. One (30B) is the first high-affinity human antibody to bind serotype B BoNT, and another (6A) is able to neutralize a lethal dose of serotype A BoNT in vivo in pre- and post-exposure models. This optimized hybridoma method will broadly enable access to the native human antibody repertoire.
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Affiliation(s)
- Sharad P Adekar
- Cardeza Foundation for Hematologic Research and Kimmel Cancer Center, Thomas Jefferson University, 1015 Walnut Street, Philadelphia, PA 19107, United States
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Elias MD, Nakamura S, Migita CT, Miyoshi H, Toyama H, Matsushita K, Adachi O, Yamada M. Occurrence of a bound ubiquinone and its function in Escherichia coli membrane-bound quinoprotein glucose dehydrogenase. J Biol Chem 2003; 279:3078-83. [PMID: 14612441 DOI: 10.1074/jbc.m310163200] [Citation(s) in RCA: 27] [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: 11/06/2022] Open
Abstract
The membrane-bound pyrroloquinoline quinone (PQQ)-containing quinoprotein glucose dehydrogenase (mGDH) in Escherichia coli functions by catalyzing glucose oxidation in the periplasm and by transferring electrons directly to ubiquinone (UQ) in the respiratory chain. To clarify the intramolecular electron transfer of mGDH, quantitation and identification of UQ were performed, indicating that purified mGDH contains a tightly bound UQ(8) in its molecule. A significant increase in the EPR signal was observed following glucose addition in mGDH reconstituted with PQQ and Mg(2+), suggesting that bound UQ(8) accepts a single electron from PQQH(2) to generate semiquinone radicals. No such increase in the EPR signal was observed in UQ(8)-free mGDH under the same conditions. Moreover, a UQ(2) reductase assay with a UQ-related inhibitor (C49) revealed different inhibition kinetics between the wild-type mGDH and UQ(8)-free mGDH. From these findings, we propose that the native mGDH bears two ubiquinone-binding sites, one (Q(I)) for bound UQ(8) in its molecule and the other (Q(II)) for UQ(8) in the ubiquinone pool, and that the bound UQ(8) in the Q(I) site acts as a single electron mediator in the intramolecular electron transfer in mGDH.
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Affiliation(s)
- M D Elias
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
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Yamada M, Elias MD, Matsushita K, Migita CT, Adachi O. Escherichia coli PQQ-containing quinoprotein glucose dehydrogenase: its structure comparison with other quinoproteins. Biochim Biophys Acta 2003; 1647:185-92. [PMID: 12686131 DOI: 10.1016/s1570-9639(03)00100-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane-bound glucose dehydrogenase (mGDH) in Escherichia coli is one of the pivotal pyrroloquinoline quinone (PQQ)-containing quinoproteins coupled with the respiratory chain in the periplasmic oxidation of alcohols and sugars in Gram-negative bacteria. We compared mGDH with other PQQ-dependent quinoproteins in molecular structure and attempted to trace their evolutionary process. We also review the role of residues crucial for the catalytic reaction or for interacting with PQQ and discuss the functions of two distinct domains, radical formation in PQQ, and the presumed existence of bound quinone in mGDH.
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Affiliation(s)
- Mamoru Yamada
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
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Izu H, Ito S, Elias MD, Yamada M. Differential control by IHF and cAMP of two oppositely oriented genes, hpt and gcd, in Escherichia coli: significance of their partially overlapping regulatory elements. Mol Genet Genomics 2002; 266:865-72. [PMID: 11810262 DOI: 10.1007/s00438-001-0608-7] [Citation(s) in RCA: 6] [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] [Received: 05/26/2001] [Accepted: 10/12/2001] [Indexed: 10/27/2022]
Abstract
The hpt gene, which encodes hypoxanthine phosphoribosyltransferase, is located next to, but transcribed in the opposite direction to, the gcd gene, which codes for a membrane-bound glucose dehydrogenase, at 3.1 min on the Escherichia coli genome. In their promoter-operator region, putative regulatory elements for integration host factor (IHF) and for the complex comprising 3', 5'-cyclic AMP (cAMP) and its receptor protein (CRP) are present, and they overlap the promoters for hpt and gcd, respectively. The involvement of IHF and cAMP-CRP, as well as the corresponding putative cis-acting elements, in the expression of the two genes was investigated by using lacZ operon fusions. In an adenylate cyclase-deficient strain, addition of cAMP increased the expression of hpt and reduced the expression of gcd. In agreement with this observation, the introduction of mutations into the putative binding element for the cAMP-CRP complex enhanced the expression of gcd. In contrast, mutations introduced into the putative IHF-binding elements increased the level of hpt expression. Similar results were obtained with IHF-defective strains. Thus, the expression of the two genes is regulated in a mutually exclusive manner. Additional experiments with mutations at the -10 sequence of the gcd promoter suggest that the binding of RNA polymerase to the hpt promoter interferes with the interaction of RNA polymerase with the gcd promoter, and vice versa.
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Affiliation(s)
- H Izu
- Department of Biological Biochemistry, Faculty of Agriculture, Yamaguchi University, Ube, Yamaguchi 755-8505, Japan
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Elias MD, Tanaka M, Izu H, Matsushita K, Adachi O, Yamada M. Functions of amino acid residues in the active site of Escherichia coli pyrroloquinoline quinone-containing quinoprotein glucose dehydrogenase. J Biol Chem 2000; 275:7321-6. [PMID: 10702303 DOI: 10.1074/jbc.275.10.7321] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several mutants of quinoprotein glucose dehydrogenase (GDH) in Escherichia coli, located around its cofactor pyrroloquinoline quinone (PQQ), were constructed by site-specific mutagenesis and characterized by enzymatic and kinetic analyses. Of these, critical mutants were further characterized after purification or by different amino acid substitutions. H262A mutant showed reduced affinities both for glucose and PQQ without significant effect on glucose oxidase activity, indicating that His-262 occurs very close to PQQ and glucose, but is not the electron acceptor from PQQH(2). W404A and W404F showed pronounced reductions of affinity for PQQ, and the latter rather than the former had equivalent glucose oxidase activity to the wild type, suggesting that Trp-404 may be a support for PQQ and important for the positioning of PQQ. D466N, D466E, and K493A showed very low glucose oxidase activities without influence on the affinity for PQQ. Judging from the enzyme activities of D466E and K493A, as well as their absorption spectra of PQQ during glucose oxidation, we conclude that Asp-466 initiates glucose oxidation reaction by abstraction of a proton from glucose and Lys-493 is involved in electron transfer from PQQH(2).
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Affiliation(s)
- M D Elias
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
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