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Enkhmaa D, Munkhuu B, Baatar T, Purevsuren J, Minjuur E, Luuzanbadam G, MacKenzie R, Warburton D, Enkhtur S. Overview of Telemedicine Services in Mongolia. Curr Pediatr Rep 2021; 9:77-82. [PMID: 34258106 PMCID: PMC8270234 DOI: 10.1007/s40124-021-00245-w] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/29/2021] [Indexed: 11/25/2022]
Abstract
Purpose of Review To highlight some achievements made through usage of telecommunication technologies in Mongolia as an example of a developing country with remote areas. Recent Findings Telemedicine can be implemented not only for remote monitoring, diagnosing, and treating purposes but also can be effectively used for delivering knowledge and consultation services via modern technologies. Summary Tele-health services can be successfully added to the traditional approach of physicians, especially in the countries with a vast territory with distant areas.
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Affiliation(s)
- D. Enkhmaa
- National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - B. Munkhuu
- National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - T. Baatar
- UNFPA Country Office, Ulaanbaatar, Mongolia
| | - J. Purevsuren
- National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - E. Minjuur
- National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - G. Luuzanbadam
- National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - R. MacKenzie
- Children’s Hospital Los Angeles, Los Angeles, CA USA
| | - D. Warburton
- Children’s Hospital Los Angeles, Los Angeles, CA USA
| | - Sh. Enkhtur
- National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
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Bélanger K, Iqbal U, Tanha J, MacKenzie R, Moreno M, Stanimirovic D. Single-Domain Antibodies as Therapeutic and Imaging Agents for the Treatment of CNS Diseases. Antibodies (Basel) 2019; 8:antib8020027. [PMID: 31544833 PMCID: PMC6640712 DOI: 10.3390/antib8020027] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 03/25/2019] [Accepted: 03/28/2019] [Indexed: 01/06/2023] Open
Abstract
Antibodies have become one of the most successful therapeutics for a number of oncology and inflammatory diseases. So far, central nervous system (CNS) indications have missed out on the antibody revolution, while they remain 'hidden' behind several hard to breach barriers. Among the various antibody modalities, single-domain antibodies (sdAbs) may hold the 'key' to unlocking the access of antibody therapies to CNS diseases. The unique structural features of sdAbs make them the smallest monomeric antibody fragments suitable for molecular targeting. These features are of particular importance when developing antibodies as modular building blocks for engineering CNS-targeting therapeutics and imaging agents. In this review, we first introduce the characteristic properties of sdAbs compared to traditional antibodies. We then present recent advances in the development of sdAbs as potential therapeutics across brain barriers, including their use for the delivery of biologics across the blood-brain and blood-cerebrospinal fluid (CSF) barriers, treatment of neurodegenerative diseases and molecular imaging of brain targets.
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Affiliation(s)
- Kasandra Bélanger
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
| | - Umar Iqbal
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
| | - Jamshid Tanha
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
| | - Roger MacKenzie
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
| | - Maria Moreno
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
| | - Danica Stanimirovic
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
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Grundy J, Hancock M, Meixner S, MacKenzie R, Koschinsky M, Pryzdial E. Plasminogen binds to plasmin-modulated factor Xa by Ca2+- and C-terminal lysine-dependent and -independent interactions. Thromb Haemost 2017. [DOI: 10.1160/th06-08-0476] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SummaryPlasminogen binding to receptors involves both C-terminal lysine-dependent and -independent interactions. The latter are poorly understood. Our earlier work demonstrated a novel Ca2+-enhanced bivalent interaction between plasmin-cleaved FXa (FXa33/13) and plasminogen truncated at Lys78 (Lys-Pg). Here we hypothesized that the effects of Ca2+may enable dissection of the C-terminal lysine-dependent and -independent interactions. To evaluate the role of the Glu-plasminogen (Glu-Pg) amino acids 1–77, binding of FXa33/13 to immobilized Glu-Pg was compared to Lys-Pg by surface plasmon resonance. Under identical conditions, approximately half the amount of FXa33/13 bound to Glu-Pg. The simplest fit of data suggested a 2:1 plasminogen:FXa33/13 stoichiometry for both, which were proportionately enhanced by Ca2+. Only Lys-Pg demonstrated significant Ca2+-independent binding to FXa33/13. In the presence of Ca2+, weak C-terminal lysine-independent binding could be detected, but only for Glu-Pg. The elastase-generated plasminogen fragment encompassing the angiostatin-like kringle domains 1 to 3 (K1–3) inhibited binding of FXa33/13 to Lys-Pg, whereas fragments corresponding to kringle 4- and kringle 5-protease domain had no effect. Immobilized K1–3 binding to FXa33/13 had both Ca2+-dependent and -independent components. The principal KMd for the interaction was 10-fold higher than Lys-Pg. In the presence of Ca2+, eACA inhibited FXa33/13 binding to K1–3 by 30%, but eliminated binding in the absence of Ca2+. These studies suggest that Ca2+-dependent and -independent binding of Lys-Pg to FXa33/13 are C-terminal lysine-dependent. The N-terminal 1–77 amino acids of Glu-Pg confer significant C-terminal lysine-independent binding, which may play a role during the initiating stages of plasminogen activation.
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Liu P, Hedani T, Delagrammatikas L, Nielsen J, Lindberg S, Alire C, Skezas S, MacKenzie R. EVALUATING CALIFORNIA’S READINESS TO PARTICIPATE IN THE NATIONAL ADULT MALTREATMENT REPORTING SYSTEM. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.4622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- P. Liu
- UCSF, Walnut Creek, California,
| | - T. Hedani
- Institute on Aging, San Francisco, California
| | | | - J. Nielsen
- City/County of San Francisco, San Francisco, California,
| | | | - C. Alire
- San Diego County, San Diego, California,
| | - S. Skezas
- Santa Cruz County, Santa Cruz, California,
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Abulrob A, Mercier M, Corluka S, MacKenzie R, Raphael S, Michienzi S, Savill J, Gui Y, Maksymowych W, Marotta A. THU0073 14-3-3ETA as a Novel RA Drug Target: Anti-14-3-3ETA Monoclonal Antibody Delays the Onset and Mitigates the Severity of Arthritis in CIA MICE. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-eular.2404] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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6
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Kim DY, To R, Kandalaft H, Ding W, van Faassen H, Luo Y, Schrag JD, St-Amant N, Hefford M, Hirama T, Kelly JF, MacKenzie R, Tanha J. Antibody light chain variable domains and their biophysically improved versions for human immunotherapy. MAbs 2014; 6:219-35. [PMID: 24423624 PMCID: PMC3929445 DOI: 10.4161/mabs.26844] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [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] [Indexed: 01/03/2023] Open
Abstract
We set out to gain deeper insight into the potential of antibody light chain variable domains (VLs) as immunotherapeutics. To this end, we generated a naïve human VL phage display library and, by using a method previously shown to select for non-aggregating antibody heavy chain variable domains (VHs), we isolated a diversity of VL domains by panning the library against B cell super-antigen protein L. Eight domains representing different germline origins were shown to be non-aggregating at concentrations as high as 450 µM, indicating VL repertoires are a rich source of non-aggregating domains. In addition, the VLs demonstrated high expression yields in E. coli, protein L binding and high reversibility of thermal unfolding. A side-by-side comparison with a set of non-aggregating human VHs revealed that the VLs had similar overall profiles with respect to melting temperature (Tm), reversibility of thermal unfolding and resistance to gastrointestinal proteases. Successful engineering of a non-canonical disulfide linkage in the core of VLs did not compromise the non-aggregation state or protein L binding properties. Furthermore, the introduced disulfide bond significantly increased their Tms, by 5.5–17.5 °C, and pepsin resistance, although it somewhat reduced expression yields and subtly changed the structure of VLs. Human VLs and engineered versions may make suitable therapeutics due to their desirable biophysical features. The disulfide linkage-engineered VLs may be the preferred therapeutic format because of their higher stability, especially for oral therapy applications that necessitate high resistance to the stomach’s acidic pH and pepsin.
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Affiliation(s)
- Dae Young Kim
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Rebecca To
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Hiba Kandalaft
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Wen Ding
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Henk van Faassen
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Yan Luo
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Joseph D Schrag
- Human Health Therapeutics; National Research Council Canada; Montréal, QC Canada
| | - Nadereh St-Amant
- Centre for Vaccine Evaluation; Biologics and Genetic Therapies Directorate;, Health Canada; Ottawa, ON Canada
| | - Mary Hefford
- Centre for Vaccine Evaluation; Biologics and Genetic Therapies Directorate;, Health Canada; Ottawa, ON Canada
| | - Tomoko Hirama
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - John F Kelly
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada
| | - Roger MacKenzie
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada; School of Environmental Sciences; Ontario Agricultural College; University of Guelph; Guelph, ON Canada
| | - Jamshid Tanha
- Human Health Therapeutics; National Research Council Canada; Ottawa, ON Canada; School of Environmental Sciences; Ontario Agricultural College; University of Guelph; Guelph, ON Canada; Department of Biochemistry, Microbiology, and Immunology; University of Ottawa; Ottawa, ON Canada
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7
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Hussack G, Riazi A, Ryan S, van Faassen H, MacKenzie R, Tanha J, Arbabi-Ghahroudi M. Protease-resistant single-domain antibodies inhibit Campylobacter jejuni motility. Protein Eng Des Sel 2014; 27:191-8. [PMID: 24742504 DOI: 10.1093/protein/gzu011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Camelid heavy-chain antibody variable domains (VHHs) are emerging as potential antimicrobial reagents. We have engineered a previously isolated VHH (FlagV1M), which binds Campylobacter jejuni flagella, for greater thermal and proteolytic stability. Mutants of FlagV1M were obtained from an error-prone polymerase chain reaction library that was panned in the presence of gastrointestinal (GI) proteases. Additional FlagV1M mutants were obtained through disulfide-bond engineering. Each approach produced VHHs with enhanced thermal stability and protease resistance. When the beneficial mutations from both approaches were combined, a hyperstabilized VHH was created with superior stability. The hyperstabilized VHH bound C. jejuni flagella with wild-type affinity and was capable of potently inhibiting C. jejuni motility in assays performed after sequential digestion with three major GI proteases, demonstrating the remarkable stability imparted to the VHH by combining our engineering approaches.
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Affiliation(s)
- Greg Hussack
- Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada K1A 0R6
| | - Ali Riazi
- AbCelex Technologies, Inc., Toronto, ON, Canada L4V 1T4
| | - Shannon Ryan
- Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada K1A 0R6
| | - Henk van Faassen
- Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada K1A 0R6
| | - Roger MacKenzie
- Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 School of Environmental Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Jamshid Tanha
- Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 School of Environmental Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1 Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada K1N 6N5
| | - Mehdi Arbabi-Ghahroudi
- Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 School of Environmental Sciences, University of Guelph, Guelph, ON, Canada N1G 2W1 Department of Biology, Carleton University, Ottawa, ON, Canada K1S 5B6
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Riazi A, Strong PCR, Coleman R, Chen W, Hirama T, van Faassen H, Henry M, Logan SM, Szymanski CM, MacKenzie R, Ghahroudi MA. Pentavalent single-domain antibodies reduce Campylobacter jejuni motility and colonization in chickens. PLoS One 2013; 8:e83928. [PMID: 24391847 PMCID: PMC3877120 DOI: 10.1371/journal.pone.0083928] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 11/08/2013] [Indexed: 11/18/2022] Open
Abstract
Campylobacter jejuni is the leading cause of bacterial foodborne illness in the world, with symptoms ranging from acute diarrhea to severe neurological disorders. Contaminated poultry meat is a major source of C. jejuni infection, and therefore, strategies to reduce this organism in poultry, are expected to reduce the incidence of Campylobacter-associated diseases. We have investigated whether oral administration of C. jejuni-specific single-domain antibodies would reduce bacterial colonization levels in chickens. Llama single-domain antibodies specific for C. jejuni were isolated from a phage display library generated from the heavy chain IgG variable domain repertoire of a llama immunized with C. jejuni flagella. Two flagella-specific single-domain antibodies were pentamerized to yield high avidity antibodies capable of multivalent binding to the target antigen. When administered orally to C. jejuni-infected two-day old chicks, the pentabodies significantly reduced C. jejuni colonization in the ceca. In vitro, the motility of the bacteria was also reduced in the presence of the flagella-specific pentabodies, suggesting the mechanism of action is through either direct interference with flagellar motility or antibody-mediated aggregation. Fluorescent microscopy and Western blot analyses revealed specific binding of the anti-flagella pentabodies to the C. jejuni flagellin.
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Affiliation(s)
- Ali Riazi
- AbCelex Technologies Inc., Toronto, Ontario, Canada
| | - Philippa C. R. Strong
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Russell Coleman
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Wangxue Chen
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Tomoko Hirama
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Henk van Faassen
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Matthew Henry
- Dow AgroSciences, Indianapolis, Indiana, United States of America
| | - Susan M. Logan
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Christine M. Szymanski
- Centennial Centre for Interdisciplinary Science, Department of Biological Sciences and Alberta Glycomics Centre, The University of Alberta, Edmonton, Alberta, Canada
| | - Roger MacKenzie
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
- Centennial Centre for Interdisciplinary Science, Department of Biological Sciences and Alberta Glycomics Centre, The University of Alberta, Edmonton, Alberta, Canada
| | - Mehdi Arbabi Ghahroudi
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
- School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
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9
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Abstract
Engineered monoclonal antibody fragments have gained market attention due to their versatility and tailor-made potential and are now considered to be an important part of future immunobiotherapeutics. Single-domain antibodies (sdAbs), also known as nanobodies, are derived from VHHs [variable domains (V) of heavy-chain-only antibodies (HCAb)] of camelid heavy-chain antibodies. These nature-made sdAbs are well suited for various applications due to their favorable characteristics such as small size, ease of genetic manipulation, high affinity and solubility, overall stability, resistance to harsh conditions (e.g., low pH, high temperature), and low immunogenicity. Most importantly, sdAbs have the feature of penetrating into cavities and recognizing hidden epitopes normally inaccessible to conventional antibodies, mainly due to their protruding CDR3/H3 loops. In this unit, we will present and discuss comprehensive and step-by-step protocols routinely practiced in our laboratory for isolating sdAbs from immunized llamas (or other members of the Camelidae family) against target antigens using phage-display technology. Expression, purification, and characterization of the isolated sdAbs will then be described, followed by presentation of several examples of applications of sdAbs previously characterized in our laboratory and elsewhere.
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Affiliation(s)
- Toya Nath Baral
- Human Health Therapeutics, Life Sciences Division, National Research Council Canada, Ottawa, Ontario, Canada
| | - Roger MacKenzie
- Human Health Therapeutics, Life Sciences Division, National Research Council Canada, Ottawa, Ontario, Canada.,University of Guelph, Guelph, Ontario, Canada
| | - Mehdi Arbabi Ghahroudi
- Human Health Therapeutics, Life Sciences Division, National Research Council Canada, Ottawa, Ontario, Canada.,University of Guelph, Guelph, Ontario, Canada.,Department of Biology, Carleton University, Ottawa, Ontario, Canada
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10
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Chapman S, MacKenzie R. There's Nothing That Succeeds Like Failure: Discerning the Woods From the Trees in Smoking Cessation Debates. Nicotine Tob Res 2012; 15:750-1. [DOI: 10.1093/ntr/nts237] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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11
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Kim DY, Kandalaft H, Ding W, Ryan S, van Faassen H, Hirama T, Foote SJ, MacKenzie R, Tanha J. Disulfide linkage engineering for improving biophysical properties of human VH domains. Protein Eng Des Sel 2012; 25:581-9. [PMID: 22942392 DOI: 10.1093/protein/gzs055] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
To enhance their therapeutic potential, human antibody heavy chain variable domains (V(H)s) would benefit from increased thermostability. The highly conserved disulfide linkage that connects Cys23 and Cys104 residues in the core of V(H) domains is crucial to their stability and function. It has previously been shown that the introduction of a second disulfide linkage can increase the thermostability of camelid heavy-chain antibody variable domains (V(H)Hs). Using four model domains we demonstrate that this strategy is also applicable to human V(H) domains. The introduced disulfide linkage, formed between Cys54 and Cys78 residues, increased the thermostability of V(H)s by 14-18°C. In addition, using a novel hexa-histidine capture technology, circular dichroism, turbidity, size exclusion chromatography and multiangle light scattering measurements, we demonstrate reduced V(H) aggregation in domains with the Cys54-Cys78 disulfide linkage. However, we also found that the engineered disulfide linkage caused conformational changes, as indicated by reduced binding of the V(H)s to protein A. This indicates that it may be prudent to use the synthetic V(H) libraries harboring the engineered disulfide linkage before screening for affinity reagents. Such strategies may increase the number of thermostable binders.
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Affiliation(s)
- Dae Young Kim
- Human Health Therapeutics, National Research Council Canada, Ottawa, ON, Canada K1A 0R6
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12
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Hussack G, Keklikian A, Alsughayyir J, Hanifi-Moghaddam P, Arbabi-Ghahroudi M, van Faassen H, Hou ST, Sad S, MacKenzie R, Tanha J. A V(L) single-domain antibody library shows a high-propensity to yield non-aggregating binders. Protein Eng Des Sel 2012; 25:313-8. [PMID: 22490957 DOI: 10.1093/protein/gzs014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A synthetic human V(L) phage display library, created by the randomization of all complementarity-determining regions (CDRs) in a V(L) scaffold, was panned against three test antigens to determine the propensity of the library to yield non-aggregating binders. A total of 22 binders were isolated against the test antigens and the majority (20) were monomeric. Thus, human V(L) repertoires provide an efficient source of non-aggregating binders and represent an attractive alternative to human V(H) repertoires, which are notorious for containing high proportions of aggregating species. Moreover, the solubility of V(L)s, in contrast to V(H)s, appears much less CDR dependent.
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Affiliation(s)
- Greg Hussack
- Institute for Biological Sciences, National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6
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13
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Hussack G, Hirama T, Ding W, MacKenzie R, Tanha J. Engineered single-domain antibodies with high protease resistance and thermal stability. PLoS One 2011; 6:e28218. [PMID: 22140551 PMCID: PMC3227653 DOI: 10.1371/journal.pone.0028218] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 11/03/2011] [Indexed: 11/28/2022] Open
Abstract
The extreme pH and protease-rich environment of the upper gastrointestinal tract is a major obstacle facing orally-administered protein therapeutics, including antibodies. Through protein engineering, several Clostridium difficile toxin A-specific heavy chain antibody variable domains (VHHs) were expressed with an additional disulfide bond by introducing Ala/Gly54Cys and Ile78Cys mutations. Mutant antibodies were compared to their wild-type counterparts with respect to expression yield, non-aggregation status, affinity for toxin A, circular dichroism (CD) structural signatures, thermal stability, protease resistance, and toxin A-neutralizing capacity. The mutant VHHs were found to be well expressed, although with lower yields compared to wild-type counterparts, were non-aggregating monomers, retained low nM affinity for toxin A, albeit the majority showed somewhat reduced affinity compared to wild-type counterparts, and were capable of in vitro toxin A neutralization in cell-based assays. Far-UV and near-UV CD spectroscopy consistently showed shifts in peak intensity and selective peak minima for wild-type and mutant VHH pairs; however, the overall CD profile remained very similar. A significant increase in the thermal unfolding midpoint temperature was observed for all mutants at both neutral and acidic pH. Digestion of the VHHs with the major gastrointestinal proteases, at biologically relevant concentrations, revealed a significant increase in pepsin resistance for all mutants and an increase in chymotrypsin resistance for the majority of mutants. Mutant VHH trypsin resistance was similar to that of wild-type VHHs, although the trypsin resistance of one VHH mutant was significantly reduced. Therefore, the introduction of a second disulfide bond in the hydrophobic core not only increases VHH thermal stability at neutral pH, as previously shown, but also represents a generic strategy to increase VHH stability at low pH and impart protease resistance, with only minor perturbations in target binding affinities. These are all desirable characteristics for the design of protein-based oral therapeutics.
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Affiliation(s)
- Greg Hussack
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Tomoko Hirama
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
| | - Wen Ding
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
| | - Roger MacKenzie
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
- School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jamshid Tanha
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada
- * E-mail:
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Hussack G, Arbabi-Ghahroudi M, van Faassen H, Songer JG, Ng KKS, MacKenzie R, Tanha J. Neutralization of Clostridium difficile toxin A with single-domain antibodies targeting the cell receptor binding domain. J Biol Chem 2011; 286:8961-76. [PMID: 21216961 DOI: 10.1074/jbc.m110.198754] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile is a leading cause of nosocomial infection in North America and a considerable challenge to healthcare professionals in hospitals and nursing homes. The gram-positive bacterium produces two high molecular weight exotoxins, toxin A (TcdA) and toxin B (TcdB), which are the major virulence factors responsible for C. difficile-associated disease and are targets for C. difficile-associated disease therapy. Here, recombinant single-domain antibody fragments (V(H)Hs), which specifically target the cell receptor binding domains of TcdA or TcdB, were isolated from an immune llama phage display library and characterized. Four V(H)Hs (A4.2, A5.1, A20.1, and A26.8), all shown to recognize conformational epitopes, were potent neutralizers of the cytopathic effects of toxin A on fibroblast cells in an in vitro assay. The neutralizing potency was further enhanced when V(H)Hs were administered in paired or triplet combinations at the same overall V(H)H concentration, suggesting recognition of nonoverlapping TcdA epitopes. Biacore epitope mapping experiments revealed that some synergistic combinations consisted of V(H)Hs recognizing overlapping epitopes, an indication that factors other than mere epitope blocking are responsible for the increased neutralization. Further binding assays revealed TcdA-specific V(H)Hs neutralized toxin A by binding to sites other than the carbohydrate binding pocket of the toxin. With favorable characteristics such as high production yield, potent toxin neutralization, and intrinsic stability, these V(H)Hs are attractive systemic therapeutics but are more so as oral therapeutics in the destabilizing environment of the gastrointestinal tract.
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Affiliation(s)
- Greg Hussack
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
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Flynn C, Khaouam N, Gardner S, Higgins K, Enepekides D, Balogh J, MacKenzie R, Singh S, Davidson J, Poon I. The Value of Periodic Follow-up in the Detection of Recurrences after Radical Treatment in Locally Advanced Head and Neck Cancer. Clin Oncol (R Coll Radiol) 2010; 22:868-73. [DOI: 10.1016/j.clon.2010.05.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 04/14/2010] [Accepted: 05/12/2010] [Indexed: 01/20/2023]
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16
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Waseh S, Hanifi-Moghaddam P, Coleman R, Masotti M, Ryan S, Foss M, MacKenzie R, Henry M, Szymanski CM, Tanha J. Orally administered P22 phage tailspike protein reduces salmonella colonization in chickens: prospects of a novel therapy against bacterial infections. PLoS One 2010; 5:e13904. [PMID: 21124920 PMCID: PMC2989905 DOI: 10.1371/journal.pone.0013904] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 10/12/2010] [Indexed: 12/14/2022] Open
Abstract
One of the major causes of morbidity and mortality in man and economically important animals is bacterial infections of the gastrointestinal (GI) tract. The emergence of difficult-to-treat infections, primarily caused by antibiotic resistant bacteria, demands for alternatives to antibiotic therapy. Currently, one of the emerging therapeutic alternatives is the use of lytic bacteriophages. In an effort to exploit the target specificity and therapeutic potential of bacteriophages, we examined the utility of bacteriophage tailspike proteins (Tsps). Among the best-characterized Tsps is that from the Podoviridae P22 bacteriophage, which recognizes the lipopolysaccharides of Salmonella enterica serovar Typhimurium. In this study, we utilized a truncated, functionally equivalent version of the P22 tailspike protein, P22sTsp, as a prototype to demonstrate the therapeutic potential of Tsps in the GI tract of chickens. Bacterial agglutination assays showed that P22sTsp was capable of agglutinating S. Typhimurium at levels similar to antibodies and incubating the Tsp with chicken GI fluids showed no proteolytic activity against the Tsp. Testing P22sTsp against the three major GI proteases showed that P22sTsp was resistant to trypsin and partially to chymotrypsin, but sensitive to pepsin. However, in formulated form for oral administration, P22sTsp was resistant to all three proteases. When administered orally to chickens, P22sTsp significantly reduced Salmonella colonization in the gut and its further penetration into internal organs. In in vitro assays, P22sTsp effectively retarded Salmonella motility, a factor implicated in bacterial colonization and invasion, suggesting that the in vivo decolonization ability of P22sTsp may, at least in part, be due to its ability to interfere with motility… Our findings show promise in terms of opening novel Tsp-based oral therapeutic approaches against bacterial infections in production animals and potentially in humans.
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Affiliation(s)
- Shakeeba Waseh
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
| | | | - Russell Coleman
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
| | - Michael Masotti
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
| | - Shannon Ryan
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
| | - Mary Foss
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
| | - Roger MacKenzie
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
- Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Guelph, Canada
| | - Matthew Henry
- Department of Discovery Research, Dow AgroSciences, Indianapolis, Indiana, United States of America
| | | | - Jamshid Tanha
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada
- Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Guelph, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
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17
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Vena D, Poon I, Kusano M, Banihashemi B, Balogh J, MacKenzie R, Davidson J, Higgins K, Enepekides D, Caldwell C. A Preliminary Analysis to Assess Intra-treatment FDG-PET Parameters that Predict for Locoregional Control in Advanced Head and Neck Cancer Treated with Chemoradiation. Int J Radiat Oncol Biol Phys 2009. [DOI: 10.1016/j.ijrobp.2009.07.966] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Ryan S, Kell AJ, van Faassen H, Tay LL, Simard B, MacKenzie R, Gilbert M, Tanha J. Single-domain antibody-nanoparticles: promising architectures for increased staphylococcus aureus detection specificity and sensitivity. Bioconjug Chem 2009; 20:1966-74. [PMID: 19751063 DOI: 10.1021/bc900332r] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Because antibodies are highly target-specific and nanoparticles possess diverse, material-dependent properties that can be exploited in order to label and potentially identify biomolecules, the development of antibody-nanoparticle conjugates (nanoconjugates) has huge potential in biodiagnostics. Here, we describe a novel superparamagnetic nanoconjugate, one whose recognition component is a single-domain antibody. It is highly active toward its target Staphylococcus aureus, displays long shelf life, lacks cross-reactivity inherent to traditional homologue whole antibodies, and captures a few dozen S. aureus cells in a mixed cell population with ~100% efficiency and specificity. We ascribe the excellent performance of our nanoconjugate to its single-domain antibody component and recommend it as a general purpose recognition element.
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Affiliation(s)
- Shannon Ryan
- Institute for Biological Sciences, Steacie Institute for Molecular Sciences, and Institute for Microstructural Sciences, National Research Council Canada, Ottawa, Ontario, Canada
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Yu H, Caldwell C, Mah K, Poon I, Balogh J, MacKenzie R. Poster - Wed Eve-44: CO-Registered Multi-Modality Pattern Analysis Segmentation System (COMPASS) for Radiation Targeting of Head and Neck Cancer Using FDG PET/CT. Med Phys 2009. [DOI: 10.1118/1.3244148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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20
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Basran PS, MacKenzie R, Poon I, Balogh J, Chan T. Poster - Wed Eve-38: Comparison of IMRT Plan Quality from Two Different Linear Accelerator. Med Phys 2009. [DOI: 10.1118/1.3244142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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21
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Vena D, Poon I, Yu H, Kusano M, MacKenzie R, Balogh J, Banihashemi B, Higgins K, Enepekides D, Davidson J, Caldwell C. 89 THE USE OF AN AUTOMATED SEGMENTATION ALGORITHM AS A METHOD FOR WHOLE TUMOUR ROI DEFINITION TO IMPROVE THE ACCURACY AND STABILITY OF INTRA-TREATMENT FDG ASSESSMENT IN HEAD AND NECK CANCER. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72476-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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22
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Hussack G, Luo Y, Veldhuis L, Hall JC, Tanha J, MacKenzie R. Multivalent anchoring and oriented display of single-domain antibodies on cellulose. Sensors (Basel) 2009; 9:5351-67. [PMID: 22346702 PMCID: PMC3274147 DOI: 10.3390/s90705351] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Revised: 06/11/2009] [Accepted: 07/07/2009] [Indexed: 11/26/2022]
Abstract
Antibody engineering has allowed for the rapid generation of binding agents against virtually any antigen of interest, predominantly for therapeutic applications. Considerably less attention has been given to the development of diagnostic reagents and biosensors using engineered antibodies. Recently, we produced a novel pentavalent bispecific antibody (i.e., decabody) by pentamerizing two single-domain antibodies (sdAbs) through the verotoxin B subunit (VTB) and found both fusion partners to be functional. Using a similar approach, we have engineered a bispecific pentameric fusion protein consisting of five sdAbs and five cellulose-binding modules (CBMs) linked via VTB. To find an optimal design format, we constructed six bispecific pentamers consisting of three different CBMs, fused to the Staphylococcus aureus-specific human sdAb HVHP428, in both orientations. One bispecific pentamer, containing an N-terminal CBM9 and C-terminal HVHP428, was soluble, non-aggregating, and did not degrade upon storage at 4 °C for over six months. This molecule was dually functional as it bound to cellulose-based filters as well as S. aureus cells. When impregnated in cellulose filters, the bispecific pentamer recognized S. aureus cells in a flow-through detection assay. The ability of pentamerized CBMs to bind cellulose may form the basis of an immobilization platform for multivalent display of high-avidity binding reagents on cellulosic filters for sensing of pathogens, biomarkers and environmental pollutants.
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Affiliation(s)
- Greg Hussack
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada, K1A 0R6
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada, K1H 8M5
| | - Yan Luo
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada, K1A 0R6
| | - Linda Veldhuis
- Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - J. Christopher Hall
- Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Jamshid Tanha
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada, K1A 0R6
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada, K1H 8M5
- Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Roger MacKenzie
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada, K1A 0R6
- Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-613-990-0833; Fax: +1-613-952-9092
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Abstract
Techniques developed over the past 20 years for the display of foreign peptides and proteins on the surfaces of filamentous bacteriophages have been a major driving force in the rapid development of recombinant antibody technology in recent years. With phage display of antibodies as one of its key components, recombinant antibody technology has led to the development of an increasing number of therapeutic monoclonal antibodies. Antibody gene libraries are fused to a gene encoding a phage coat protein. Recombinant phage expressing the resulting antibody libraries in fusion with the coat protein are propagated in Escherichia coli. Phage displaying monoclonal antibodies with specificities for target antigens are isolated from the libraries by a process called panning. The genes encoding the desired antibodies selected from the libraries are packaged within the phage particles, linking genotype and phenotype. Here, we describe the application of this technology to the construction of a phage-displayed single-domain antibody (sdAb) library based on the heavy chain antibody repertoire of a llama, the panning of the library against a peptide antigen and the expression, purification, and characterization of sdAbs isolated by panning.
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Affiliation(s)
- Mehdi Arbabi-Ghahroudi
- Institute for Biological Sciences, National Research Council, The Antibody Engineering Group, Ottawa, Ontario, Canada
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24
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Abstract
The particular interest in VH antibody fragments stems from the fact that they can rival their "naturally occurring" single-domain antibody (sdAb) counterparts (camelid VHHs and shark VNARs) with regard to such desirable characteristics as stability, solubility, expression, and ability to penetrate cryptic epitopes and outperform them in terms of less immunogenicity, a much valued property in human immunotherapy applications. However, human VHs are typically prone to aggregation. Various approaches for developing non-aggregating human VHs with binding specificities have relied on a combination of recombinant DNA technology and phage-display technology. VH gene libraries are constructed synthetically by randomizing the CDRs of a single VH scaffold fused to a gene encoding a phage coat protein. Recombinant phage expressing the resulting VH libraries in fusion with the pIII protein is propagated in Escherichia coli. Monoclonal phage displaying VHs with specificities for target antigens are isolated from the libraries by a process called panning. The exertion of stability pressure in addition to binding pressure during panning ensures that the isolated VH binders are also non-aggregating. The genes encoding the desired VHs selected from the libraries are packaged within the phage particles, linking genotype and phenotype, hence making possible the identification of the selected VHs through identifying its physically linked genotype. Here, we describe the application of recombinant DNA and phage-display technologies for the construction of a phage-displayed human VH library, the panning of the library against a protein, and the expression, purification, and characterization of non-aggregating VHs isolated by panning.
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Affiliation(s)
- Mehdi Arbabi-Ghahroudi
- National Research Council of Canada, Institute for Biological Sciences, Ottawa, Ontario, Canada
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Arbabi-Ghahroudi M, To R, Gaudette N, Hirama T, Ding W, MacKenzie R, Tanha J. Aggregation-resistant VHs selected by in vitro evolution tend to have disulfide-bonded loops and acidic isoelectric points. Protein Eng Des Sel 2008; 22:59-66. [DOI: 10.1093/protein/gzn071] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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26
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Mah K, Caldwell C, Poon I, Balogh J, MacKenzie R, Tirona R, Chong R. Variability in Identification of Positive Nodes for Head and Neck Cancers: Comparison of CT Alone with PET-CT. Int J Radiat Oncol Biol Phys 2008. [DOI: 10.1016/j.ijrobp.2008.06.194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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27
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Lee K, Kinh H, MacKenzie R, Gilmore A, Minh N, Collin J. Gaining access to Vietnam's cigarette market: British American Tobacco's strategy to enter ‘a huge market which will become enormous’. Glob Public Health 2008; 3:1-25. [PMID: 19288356 DOI: 10.1080/17441690701589789] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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MacKenzie R, Lim JJ, Bull S, Sujecki S, Kent AJ, Larkins EC. The impact of hot-phonons on the performance of 1.3µm dilute nitride edge-emitting quantum well lasers. ACTA ACUST UNITED AC 2007. [DOI: 10.1088/1742-6596/92/1/012068] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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MacKenzie R, Rupp V, Fredericks K, Allen M, Moll L. 69: Implementation of Electronic Documentation and its Effect on Un-billable Units in the Emergency Department. Ann Emerg Med 2007. [DOI: 10.1016/j.annemergmed.2007.06.100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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30
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Greenberg M, MacKenzie R, Richardson D, Rossi M, Rupp V, Anne C, Kimmel MS. Gender Differences in Acute Cardiac Care: Where it is not. Acad Emerg Med 2007. [DOI: 10.1197/j.aem.2007.03.1065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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31
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Noestheden M, Hu Q, Tay LL, Tonary AM, Stolow A, MacKenzie R, Tanha J, Pezacki JP. Synthesis and characterization of CN-modified protein analogues as potential vibrational contrast agents. Bioorg Chem 2007; 35:284-93. [PMID: 17316745 DOI: 10.1016/j.bioorg.2006.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 12/20/2006] [Accepted: 12/29/2006] [Indexed: 10/23/2022]
Abstract
A recombinant VH single-domain antibody recognizing staphylococcal protein A was functionalized on reactive lysine residues with N-hydroxysuccimidyl-activated 4-cyanobenzoate. Surface plasmon resonance analysis of antibody-antigen binding revealed that modified and unmodified antibodies bound protein A with similar affinities. Raman imaging of the modified antibodies indicated that the benzonitrile group provides vibrational contrast enhancement in a region of the electromagnetic spectrum that is transparent to cellular materials. Thus, the modified single-domain antibody may be amenable to detecting protein A from samples of the human pathogen Staphylococcus aureus using vibronic detection schemes such as Raman and coherent anti-Stokes Raman scattering. The generality of this labeling strategy should make it applicable to modifying an array of proteins with varied structure and function.
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Affiliation(s)
- Matthew Noestheden
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Canada
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32
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Mah K, Caldwell C, Poon I, Balogh J, MacKenzie R, Tirona R. 2369. Int J Radiat Oncol Biol Phys 2006. [DOI: 10.1016/j.ijrobp.2006.07.778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Altman E, Harrison BA, Hirama T, Chandan V, To R, MacKenzie R. Characterization of murine monoclonal antibodies against Helicobacter pylori lipopolysaccharide specific for Lex and Ley blood group determinants. Biochem Cell Biol 2006; 83:589-96. [PMID: 16234847 DOI: 10.1139/o05-052] [Citation(s) in RCA: 14] [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: 11/22/2022] Open
Abstract
The cell envelope of Helicobacter pylori contains lipopolysaccharide (LPS), the O-chain of which expresses type 2 Lex and Ley blood group antigens, which mimic human gastric mucosal cell-surface glycoconjugates and may contribute to the survival of H. pylori in gastric mucosa. Here we describe the generation of monoclonal antibodies specific for Lex and Ley blood group determinants and the characterization of their binding properties using purified, structurally defined H. pylori LPS, synthetic glycoconjugates, and H. pylori cells. Analysis of oligosaccharide binding by SPR provided a rapid and reliable means for characterization of antibody affinities. One of the antibodies, anti-Lex, was of IgG3 subclass and had superior binding characteristics as compared with the commercially available anti-Lex IgM. These antibodies could have potential in the immunodiagnosis of certain types of cancer, in serotyping of H. pylori isolates, and in structure-function studies.
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Affiliation(s)
- Eleonora Altman
- Institute for Biological Sciences, NationalResearch Council of Canada, Ottawa, ON K1A 0R6, Canada.
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35
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Abstract
Maximizing the expression yields of recombinant whole antibodies and antibody fragments such as Fabs, single-chain Fvs and single-domain antibodies is highly desirable since it leads to lower production costs. Various eukaryotic and prokaryotic expression systems have been exploited to accommodate antibody expression but Escherichia coli systems have enjoyed popularity, in particular with respect to antibody fragments, because of their low cost and convenience. In many instances, product yields have been less than adequate and intrinsic and extrinsic variables have been investigated in an effort to improve yields. This review deals with various aspects of antibody expression in E. coli with a particular focus on single-domain antibodies.
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Affiliation(s)
- Mehdi Arbabi-Ghahroudi
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
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Müller-Loennies S, Gronow S, Brade L, MacKenzie R, Kosma P, Brade H. A monoclonal antibody against a carbohydrate epitope in lipopolysaccharide differentiates Chlamydophila psittaci from Chlamydophila pecorum, Chlamydophila pneumoniae, and Chlamydia trachomatis. Glycobiology 2005; 16:184-96. [PMID: 16282606 DOI: 10.1093/glycob/cwj055] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [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: 12/15/2022] Open
Abstract
Lipopolysaccharide (LPS) of Chlamydophila psittaci but not of Chlamydophila pneumoniae or Chlamydia trachomatis contains a tetrasaccharide of 3-deoxy-alpha-d-manno-oct-2-ulopyranosonic acid (Kdo) of the sequence Kdo(2-->8)[Kdo(2-->4)] Kdo(2-->4)Kdo. After immunization with the synthetic neoglycoconjugate antigen Kdo(2-->8)[Kdo(2-->4)]Kdo(2-->4) Kdo-BSA, we obtained the mouse monoclonal antibody (mAb) S69-4 which was able to differentiate C. psittaci from Chlamydophila pecorum, C. pneumoniae, and C. trachomatis in double labeling experiments of infected cell monolayers and by enzyme-linked immunosorbent assay (ELISA). The epitope specificity of mAb S69-4 was determined by binding and inhibition assays using bacteria, LPS, and natural or synthetic Kdo oligosaccharides as free ligands or conjugated to BSA. The mAb bound preferentially Kdo(2-->8)[Kdo(2-->4)]Kdo(2-->4)Kdo(2-->4) with a K(d) of 10 microM, as determined by surface plasmon resonance (SPR) for the monovalent interaction using mAb or single chain Fv. Cross-reactivity was observed with Kdo(2-->4)Kdo(2-->4) Kdo but not with Kdo(2-->8)Kdo(2-->4)Kdo, Kdo disaccharides in 2-->4- or 2-->8-linkage, or Kdo monosaccharide. MAb S69-4 was able to detect LPS on thin-layer chromatography (TLC) plates in amounts of <10 ng by immunostaining. Due to the high sensitivity achieved in this assay, the antibody also detected in vitro products of cloned Kdo transferases of Chlamydia. The antibody can therefore be used in medical and veterinarian diagnostics, general microbiology, analytical biochemistry, and studies of chlamydial LPS biosynthesis. Further contribution to the general understanding of carbohydrate-binding antibodies was obtained by a comparison of the primary structure of mAb S69-4 to that of mAb S45-18 of which the crystal structure in complex with its ligand has been elucidated recently (Nguyen et al., 2003, Nat. Struct. Biol., 10, 1019-1025).
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Affiliation(s)
- Sven Müller-Loennies
- Research Center Borstel, Leibniz Center for Medicine and Biosciences, Parkallee 22, D-23845 Borstel, Germany
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Abstract
Human V(H) domains are promising molecules in applications involving antibodies, in particular, immunotherapy because of their human origin. However, they are, in general, prone to aggregation. Therefore, various strategies have been employed to acquire monomeric human V(H)s. We had previously discovered that filamentous phages displaying engineered monomeric V(H) domains gave rise to significantly larger plaques on bacterial lawns than phages displaying wild type V(H)s with aggregation tendencies. Using plaque size as the selection criterion and a phage-displayed naïve human V(H) library we identified 15 V(H)s that were monomeric. Additionally, the V(H)s demonstrated good expression yields, good refolding properties following thermal denaturation, resistance to aggregation during long incubation at 37 degrees C, and to trypsin at 37 degrees C. These 15 V(H)s should serve as good scaffolds for developing immunotherapeutics, and the selection method employed here should have general utility for isolating proteins with desirable biophysical properties.
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Affiliation(s)
- Rebecca To
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
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39
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Abulrob A, Zhang J, Tanha J, MacKenzie R, Stanimirovic D. Single domain antibodies as blood–brain barrier delivery vectors. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.ics.2005.02.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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40
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Abstract
OBJECTIVES To examine the complicity of British American Tobacco (BAT) in cigarette smuggling in Asia, and to assess the centrality of illicit trade to regional corporate strategy. METHODS Analysis of previously confidential documents from BAT's Guildford depository. An iterative strategy combined searches based on geography, organisational structure, and key personnel, while corporate euphemisms for contraband were identified by triangulation. RESULTS BAT documents demonstrate the strategic importance of smuggling across global, regional, national, and local levels. Particularly important in Asia, contraband enabled access to closed markets, created pressure for market opening, and was highly profitable. Documents demonstrate BAT's detailed oversight of illicit trade, seeking to reconcile the conflicting demands of control and deniability. CONCLUSIONS BAT documents demonstrate that smuggling has been driven by corporate objectives, indicate national measures by which the problem can be addressed, and highlight the importance of a coordinated global response via WHO's Framework Convention on Tobacco Control.
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Affiliation(s)
- J Collin
- Centre on Global Change and Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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41
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MacKenzie R, Collin J, Sopharo C, Sopheap Y. "Almost a role model of what we would like to do everywhere": British American Tobacco in Cambodia. Tob Control 2005; 13 Suppl 2:ii112-7. [PMID: 15564213 PMCID: PMC1766168 DOI: 10.1136/tc.2004.009381] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To examine British American Tobacco's (BAT's) renewed interest in Cambodia from the early 1990s, reviewing negotiations to establish a joint venture and the subsequent conduct of BAT Cambodia (BATC). METHODS Analysis of previously confidential BAT documents relevant to the Cambodian market. RESULTS With the advent of comparative political stability in the early 1990s, BAT was quick to explore the possibilities for investment. The Cambodian government urgently required foreign investment, offering inducements and assistance to investors. In developing a joint venture, BAT saw a cost effective opportunity to dominate the local market and to defend its regional interests, Cambodia being viewed as strategically located to support smuggling. Given minimal advertising regulation, BATC have undertaken wide ranging promotions and sought to prevent advances in tobacco control. CONCLUSIONS BATC is presented as a contribution to Cambodia's regeneration, but the documents highlight its exploitation of state incapacity and an escalating threat to public health.
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Affiliation(s)
- R MacKenzie
- Centre on Global Change and Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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MacKenzie R, Collin J, Sriwongcharoen K, Muggli ME. "If we can just 'stall' new unfriendly legislations, the scoreboard is already in our favour": transnational tobacco companies and ingredients disclosure in Thailand. Tob Control 2004; 13 Suppl 2:ii79-87. [PMID: 15564225 PMCID: PMC1766166 DOI: 10.1136/tc.2004.009233] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To review the strategies employed by overseas cigarette manufacturers operating in Thailand to obstruct the passage and subsequent enforcement of national public health legislation, specifically the ingredients disclosure provision of the 1992 Tobacco Products Control Act. METHODS Analysis of previously confidential tobacco industry documents relevant to non-compliance with the ingredients disclosure legislation. RESULTS Requirement for disclosure of ingredients contained in cigarettes contained in the Tobacco Products Control Act was identified by transnational tobacco companies (TTCs) not only as a significant threat to their operations in Thailand, but as a dangerous global precedent. Industry documents reveal a determined campaign to block, stall, or amend the proposed regulation during the legislative process. Industry representatives petitioned the Ministry of Health to revise the requirement from by brand disclosure to a more palatable by company submission. Strategies were adapted in the wake of the passage of the Act. Most significantly, the industry in concert with embassies in Bangkok threatened the Thai government with appeals to international trade bodies on the grounds of violation of international agreements. Industry documents also reveal that as submission of ingredient lists appeared unavoidable, leading companies operating in Thailand endeavoured to confound the disclosure requirement by disguising ingredients and reformulating brand recipes. CONCLUSIONS The evidence presented highlights the importance of ingredients regulation and demonstrates how health policy can be transformed during its implementation. A greater understanding of trade agreements emerges as a priority for global tobacco control.
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Affiliation(s)
- R MacKenzie
- Centre on Global Change and Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1 7HT, UK.
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MacKenzie R, Nimmo F, Bachoo P, Alozairi O, Brittenden J. The relationship between socio-economic status, geography, symptomatic carotid territory disease and carotid endarterectomy. Eur J Vasc Endovasc Surg 2003; 26:145-9. [PMID: 12917828 DOI: 10.1053/ejvs.2002.1949] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE recent evidence suggests a strong association between socio-economic status and atherosclerosis. However, little information exists on the relationship between socio-economic status, symptomatic carotid disease and rates of carotid endarterectomy (CEA). The aim was to evaluate the Carstair Deprivation Score (CDS) of (1) patients admitted with symptomatic carotid disease, and (2) those undergoing CEA in one health board. METHOD the CDS score was determined from the post-codes of all patients admitted with a diagnosis of transient ischaemic attack (TIA) or stroke due to cerebral infarction (ISD 9 codes 433.1, 433.09, 435, 437.1; ICD-10: 165.2, 163, 163.2, G45.1, G45.3, G45.9) between 1st April 1995 and 31st March 2000. Expected and actual rates for each of the CDS (1 to 7) were determined by direct and indirect methods of standardisation allowing for age and sex. A similar analysis was performed for patients undergoing carotid endarterectomy. Results were analysed using the Mantel-Haenszel test. Only first time admissions and CEA were included. RESULTS 1203 patients were admitted with the main diagnosis of symptomatic carotid disease. The admission rate of symptomatic patients was less than expected in the more affluent group (Carstair 1, p < 0.005) and significantly higher in the most deprived group (Carstair 7, p < 0.001). In comparison 192 patients underwent CEA. There were no differences between the expected and actual rates of CEA in each CDS, but the rates tended to be higher in the most affluent group. Geographical variation was also demonstrated with an increased rate of CEA in those patients living in the cities and a reduced rate in those in the rural communities. CONCLUSION patients from deprived socio-economic groups had a higher rate of symptomatic carotid disease, but this was not matched by an increased rate of CEA. This suggests that socio-economic inequalities in the prevalence of symptomatic carotid artery disease and treatment exist.
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Affiliation(s)
- R MacKenzie
- Department of Vascular Surgery, University of Aberdeen, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN, Scotland, UK
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El-Sayed S, Nabid A, Shelley W, Hay J, Balogh J, Gelinas M, MacKenzie R, Read N, Berthelet E, Lau H, Epstein J, Delvecchio P, Ganguly PK, Wong F, Burns P, Tu D, Pater J. Prophylaxis of radiation-associated mucositis in conventionally treated patients with head and neck cancer: a double-blind, phase III, randomized, controlled trial evaluating the clinical efficacy of an antimicrobial lozenge using a validated mucositis scoring system. J Clin Oncol 2002; 20:3956-63. [PMID: 12351592 DOI: 10.1200/jco.2002.05.046] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Mucositis occurs in almost all patients treated with radiotherapy for head and neck cancer. The aim of this multicenter, double-blind, prospective, randomized trial was to evaluate the clinical efficacy of an economically viable antimicrobial lozenge (bacitracin, clotrimazole, and gentamicin [BcoG]) in the alleviation of radiation-induced mucositis in patients with head and neck cancer. PATIENTS AND METHODS One hundred thirty-seven eligible patients were randomized to treatment with either antimicrobial lozenge (69 patients) or placebo lozenge (68 patients). The primary end point of the study was the time to development of severe mucositis from the start of radiotherapy. Secondary end points included severity and duration of mucositis, pain measurement, radiation therapy interruption, and quality of life. Mucositis was scored using a validated mucositis scoring system. RESULTS Toxicity profiles were similar between the two arms of the study. The median time to development of severe mucositis from the start of radiotherapy was 3.61 weeks on BCoG and 3.96 weeks on placebo (P =.61). There were no statistically significant differences between the arms in the extent of severe mucositis as measured by physician, in oral toxicities as recorded by patients, or in radiotherapy delays. CONCLUSION This study was conducted on the basis of a pilot study that demonstrated the BCoG lozenge to be tolerable and microbiologically efficacious. A validated mucositis scoring system was used. However, in this group of patients treated with conventional radiotherapy, the lozenge did not impact significantly on the severity of mucositis. Whether such a lozenge would be beneficial in treatment situations where rate of severe mucositis is higher (ie, in patients treated with unconventional fractionation or with concomitant chemotherapy) is unknown.
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Affiliation(s)
- S El-Sayed
- Ottawa Regional Cancer Centre, Ottawa, Ontario, Canada.
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Churg A, Dai J, Zay K, Karsan A, Hendricks R, Yee C, Martin R, MacKenzie R, Xie C, Zhang L, Shapiro S, Wright JL. Alpha-1-antitrypsin and a broad spectrum metalloprotease inhibitor, RS113456, have similar acute anti-inflammatory effects. J Transl Med 2001; 81:1119-31. [PMID: 11502863 DOI: 10.1038/labinvest.3780324] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [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: 11/08/2022] Open
Abstract
There is increasing evidence that antiproteases are able to affect the inflammatory response. To further examine this question, we administered human alpha-1-antitrypsin (alpha1AT) or a synthetic metalloprotease inhibitor (RS113456) to C57 mice followed by a single intratracheal dose of quartz, a dust that evokes a marked, lasting, polymorphonuclear leukocyte (PMN) infiltrate. At 2 hours after dust administration, both antiproteases completely suppressed silica-induced PMN influx into the lung and macrophage inflammatory protein-2 (MIP-2)/monocyte chemotactic protein-1 (MCP-1) (neutrophil/macrophage chemoattractant) gene expression, partially suppressed nuclear transcription factor kappaB (NF-kappaB) translocation, and increased inhibitor of NF-kappaB (IkappaB) levels. By 24 hours, PMN influx and connective tissue breakdown measured as lavage desmosine or hydroxyproline were still at, or close to, control levels after antiprotease treatment, and increases in NF-kappaB translocation and MIP-2/MCP-1 gene expression were variably suppressed. At both time points, neither agent prevented silica-induced increases in amount of whole lung MIP-2 or MCP-1 protein, but both did prevent increases in whole lung intercellular adhesion molecule-1 (ICAM-1) at 24 hours. Inactivating the alpha1AT by oxidation to the point that it no longer possessed antiproteolytic properties did not affect its ability to suppress inflammation. Both antiproteases also prevented the silica-induced acute inflammatory response in mice with knocked out genes for macrophage metalloelastase (MME -/-), mice that develop inflammation, but not connective tissue breakdown, and the pattern of alpha1AT breakdown fragments was identical in control and MME -/- animals. These findings suggest that, in this model of acute PMN mediated inflammation, a serine protease inhibitor and a metalloprotease inhibitor have similar anti-inflammatory properties, that inflammation is not mediated by proteolysis with generation of chemotactic matrix fragments, and that classic antiproteolysis (complexing of protease to antiprotease) probably does not play a role in suppression of inflammation. The antiproteolytic effects of these agents do not seem to be mediated by protection of endogenous alpha1AT.
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Affiliation(s)
- A Churg
- Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada.
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MacKenzie R. The Brugada syndrome--an electrocardiogram with important mortality implications. J Insur Med 2001; 33:106-9. [PMID: 11317874] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The electrocardiogram (ECG) is a valuable screening tool for increased risk in underwriting life insurance applicants. This article discusses a recently described ECG pattern associated with a high risk of sudden unexpected death.
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Affiliation(s)
- R MacKenzie
- Sun Life Financial, Third Floor Medical Department, 150 King Street West, Toronto, Ontario, Canada M5H 1J9
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Wu G, MacKenzie R, Durda PJ, Tsang P. The binding of a glycoprotein 120 V3 loop peptide to HIV-1 neutralizing antibodies. Structural implications. J Biol Chem 2000; 275:36645-52. [PMID: 10967109 DOI: 10.1074/jbc.m005369200] [Citation(s) in RCA: 19] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structural and antigenic properties of a peptide ("CRK") derived from the V3 loop of HIV-1 gp120 protein were studied using NMR and SPR techniques. The sequence of CRK corresponds to the central portion of the V3 loop containing the highly conserved "GPGR" residue sequence. Although the biological significance of this conserved sequence is unknown, the adoption of conserved secondary structure (type II beta-turn) in this region has been proposed. The tendency of CRK (while free or conjugated to protein), to adopt such structure and the influence of such structure upon CRK antigenicity were investigated by NMR and SPR, respectively. Regardless of conjugation, CRK is conformationally averaged in solution but a weak tendency of the CRK "GPGR" residues to adopt a beta-turn conformation was observed after conjugation. The influence of GPGR structure upon CRK antigenicity was investigated by measuring the affinities of two cognate antibodies: "5023A" and "5025A," for CRK, protein-conjugated CRK and gp120 protein. Each antibody bound to all the antigens with nearly the same affinity. From these data, it appears that: (a) antibody binding most likely involves an induced fit of the peptide and (b) the gp120 V3 loop is probably conformationally heterogeneous. Since 5023A and 5025A are HIV-1 neutralizing antibodies, neutralization in these cases appears to be independent of adopted GPGR beta-turn structure.
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Affiliation(s)
- G Wu
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, USA
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MacKenzie R, Newman D, Burger MM, Roy R, Kuhns WJ. Adhesion of a viral envelope protein to a non-self-binding domain of the aggregation factor in the marine sponge Microciona prolifera. Biol Bull 2000; 199:209-211. [PMID: 11081741 DOI: 10.2307/1542903] [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] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- R MacKenzie
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
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MacKenzie R. Clearing the waters over hygiene debate. Nurs Times 2000; 96:24. [PMID: 11968231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Raffaï R, Weisgraber KH, MacKenzie R, Rupp B, Rassart E, Hirama T, Innerarity TL, Milne R. Binding of an antibody mimetic of the human low density lipoprotein receptor to apolipoprotein E is governed through electrostatic forces. Studies using site-directed mutagenesis and molecular modeling. J Biol Chem 2000; 275:7109-16. [PMID: 10702278 DOI: 10.1074/jbc.275.10.7109] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Monoclonal antibody 2E8 is specific for an epitope that coincides with the binding site of the low density lipoprotein receptor (LDLR) on human apoE. Its reactivity with apoE variants resembles that of the LDLR: it binds well with apoE3 and poorly with apoE2. The heavy chain complementarity-determining region (CDRH) 2 of 2E8 shows homology to the ligand-binding domain of the LDLR. To define better the structural basis of the 2E8/apoE interaction and particularly the role of electrostatic interactions, we generated and characterized a panel of 2E8 variants. Replacement of acidic residues in the 2E8 CDRHs showed that Asp(52), Glu(53), and Asp(56) are essential for high-affinity binding. Although Asp(31) (CDRH1), Glu(58) (CDRH2), and Asp(97) (CDRH3) did not appear to be critical, the Asp(97) --> Ala variant acquired reactivity with apoE2. A Thr(57) --> Glu substitution increased affinity for both apoE3 and apoE2. The affinities of wild-type 2E8 and variants for apoE varied inversely with ionic strength, suggesting that electrostatic forces contribute to both antigen binding and isoform specificity. We propose a model of the 2E8.apoE immune complex that is based on the 2E8 and apoE crystal structures and that is consistent with the apoE-binding properties of wild-type 2E8 and its variants. Given the similarity between the LDLR and 2E8 in terms of specificity, the LDLR/ligand interaction may also have an important electrostatic component.
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Affiliation(s)
- R Raffaï
- Lipoprotein and Atherosclerosis Group, University of Ottawa Heart Institute, Ottawa Civic Hospital, Ottawa, Ontario K1Y TW7, Canada
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