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Ferreira L, Flanagan SP, Fogel R, Limson JL. Generation of epitope-specific hCG aptamers through a novel targeted selection approach. PLoS One 2024; 19:e0295673. [PMID: 38394285 PMCID: PMC10890750 DOI: 10.1371/journal.pone.0295673] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 11/28/2023] [Indexed: 02/25/2024] Open
Abstract
Human chorionic gonadotropin (hCG) is a glycoprotein hormone used as a biomarker for several medical conditions, including pregnancy, trophoblastic and nontrophoblastic cancers. Most commercial hCG tests rely on a combination of antibodies, one of which is usually specific to the C-terminal peptide of the β-subunit. However, cleavage of this region in many hCG degradation variants prevents rapid diagnostic tests from quantifying all hCG variants in serum and urine samples. An epitope contained within the core fragment, β1, represents an under-researched opportunity for developing immunoassays specific to most variants of hCG. In the study described here, we report on a SELEX procedure tailored towards the identification of two pools of aptamers, one specific to the β-subunit of hCG and another to the β1 epitope within it. The described SELEX procedure utilized antibody-blocked targets, which is an underutilized strategy to exert negative selection pressure and in turn direct aptamer enrichment to a specific epitope. We report on the first aptamers, designated as R4_64 and R6_5, each capable of recognising two distinct sites of the hCG molecule-the β-subunit and the (presumably) β1-epitope, respectively. This study therefore presents a new SELEX approach and the generation of novel aptamer sequences that display potential hCG-specific biorecognition.
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Affiliation(s)
- Lauren Ferreira
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | - Shane Patrick Flanagan
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | - Ronen Fogel
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | - Janice Leigh Limson
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, Eastern Cape, South Africa
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Chauhan RP, Fogel R, Limson J. Nanopore MinION Sequencing Generates a White Spot Syndrome Virus Genome from a Pooled Cloacal Swab Sample of Domestic Chickens in South Africa. Microorganisms 2023; 11:2802. [PMID: 38004813 PMCID: PMC10672864 DOI: 10.3390/microorganisms11112802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/05/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
White spot syndrome virus is a highly contagious pathogen affecting shrimp farming worldwide. The host range of this virus is primarily limited to crustaceans, such as shrimps, crabs, prawns, crayfish, and lobsters; however, several species of non-crustaceans, including aquatic insects, piscivorous birds, and molluscs may serve as the vectors for ecological dissemination. The present study was aimed at studying the faecal virome of domestic chickens (Gallus gallus domesticus) in Makhanda, Eastern Cape, South Africa. The cloacal swab specimens (n = 35) were collected from domestic chickens in December 2022. The cloacal swab specimens were pooled-each pool containing five cloacal swabs-for metagenomic analysis using a sequence-independent single-primer amplification protocol, followed by Nanopore MinION sequencing. While the metagenomic sequencing generated several contigs aligning with reference genomes of animal viruses, one striking observation was the presence of a White spot syndrome virus genome in one pool of cloacal swab specimens. The generated White spot syndrome virus genome was 273,795 bp in size with 88.5% genome coverage and shared 99.94% nucleotide sequence identity with a reference genome reported in China during 2018 (GenBank accession: NC_003225.3). The Neighbour-Joining tree grouped South African White spot syndrome virus genome with other White spot syndrome virus genomes reported from South East Asia. To our knowledge, this is the first report of a White spot syndrome virus genome generated from domestic chickens. The significance of White spot syndrome virus infection in domestic chickens is yet to be determined.
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Affiliation(s)
| | | | - Janice Limson
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, Eastern Cape, South Africa; (R.P.C.); (R.F.)
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Chauhan RP, Fogel R, Limson J. Overview of Diagnostic Methods, Disease Prevalence and Transmission of Mpox (Formerly Monkeypox) in Humans and Animal Reservoirs. Microorganisms 2023; 11:1186. [PMID: 37317160 DOI: 10.3390/microorganisms11051186] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/26/2023] [Accepted: 04/28/2023] [Indexed: 06/16/2023] Open
Abstract
Mpox-formerly monkeypox-is a re-emerging zoonotic virus disease, with large numbers of human cases reported during multi-country outbreaks in 2022. The close similarities in clinical symptoms that Mpox shares with many orthopoxvirus (OPXV) diseases make its diagnosis challenging, requiring laboratory testing for confirmation. This review focuses on the diagnostic methods used for Mpox detection in naturally infected humans and animal reservoirs, disease prevalence and transmission, clinical symptoms and signs, and currently known host ranges. Using specific search terms, up to 2 September 2022, we identified 104 relevant original research articles and case reports from NCBI-PubMed and Google Scholar databases for inclusion in the study. Our analyses observed that molecular identification techniques are overwhelmingly being used in current diagnoses, especially real-time PCR (3982/7059 cases; n = 41 studies) and conventional PCR (430/1830 cases; n = 30 studies) approaches being most-frequently-used to diagnose Mpox cases in humans. Additionally, detection of Mpox genomes, using qPCR and/or conventional PCR coupled to genome sequencing methods, offered both reliable detection and epidemiological analyses of evolving Mpox strains; identified the emergence and transmission of a novel clade 'hMPXV-1A' lineage B.1 during 2022 outbreaks globally. While a few current serologic assays, such as ELISA, reported on the detection of OPXV- and Mpox-specific IgG (891/2801 cases; n = 17 studies) and IgM antibodies (241/2688 cases; n = 11 studies), hemagglutination inhibition (HI) detected Mpox antibodies in human samples (88/430 cases; n = 6 studies), most other serologic and immunographic assays used were OPXV-specific. Interestingly, virus isolation (228/1259 cases; n = 24 studies), electron microscopy (216/1226 cases; n = 18 studies), and immunohistochemistry (28/40; n = 7 studies) remain useful methods of Mpox detection in humans in select instances using clinical and tissue samples. In animals, OPXV- and Mpox-DNA and antibodies were detected in various species of nonhuman primates, rodents, shrews, opossums, a dog, and a pig. With evolving transmission dynamics of Mpox, information on reliable and rapid detection methods and clinical symptoms of disease is critical for disease management.
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Affiliation(s)
- Ravendra P Chauhan
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, Eastern Cape, South Africa
| | - Ronen Fogel
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, Eastern Cape, South Africa
| | - Janice Limson
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, Eastern Cape, South Africa
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Ogunmolasuyi AM, Fogel R, Hoppe H, Goldring D, Limson J. A microfluidic paper analytical device using capture aptamers for the detection of PfLDH in blood matrices. Malar J 2022; 21:174. [PMID: 35672848 PMCID: PMC9172074 DOI: 10.1186/s12936-022-04187-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 05/19/2022] [Indexed: 11/26/2022] Open
Abstract
Background The prevalence and death rate arising from malaria infection, and emergence of other diseases showing similar symptoms to malaria require the development of malaria-specific and sensitive devices for its diagnosis. To address this, the design and fabrication of low-cost, rapid, paper-based analytical devices (µPAD) using surface-immobilized aptamers to detect the presence of a recombinant malarial biomarker—Plasmodium falciparum lactate dehydrogenase (rPfLDH)—is reported in this study. Methods Test zones on paper surfaces were created by covalently immobilizing streptavidin to the paper, subsequently attaching biotinylated aptamers to streptavidin. Aptamers selectively bound rPfLDH. The measurement of captured rPfLDH enzyme activity served as the means of detecting this biomarker. Enzyme activity across three replicate sensors was digitally quantified using the colorimetric Malstat assay. Results Screening of several different aptamers reported in the literature showed that aptamers rLDH7 and 2008s immobilized in this manner specifically recognised and captured PfLDH. Using rLDH7, the sensitivity of the µPAD sensor was evaluated and the µPAD sensor was applied for preferential detection of rPfLDH, both in buffered solutions of the protein and in spiked serum and red blood cell lysate samples. In buffered solutions, the test zone of the µPAD sensor exhibited a KD of 24 ± 11 nM and an empirical limit of detection of 17 nM, respectively, a limit similar to commercial antibody-based sensors exposed to rPfLDH. The specific recognition of 133 nM rPfLDH in undiluted serum and blood samples was demonstrated by the µPAD. Conclusion The reported µPAD demonstrates the potential of integrating aptamers into paper-based malarial rapid diagnostic tests. Graphical Abstract The assembly of µPAD sensors using APTEC assay principles for the detection the malarial biomarker, lactate dehydrogenase enzymes from Plasmodium falciparum (PfLDH). The aptamers immobilized at the test zones capture the PfLDH in samples. After washing the unbound sample components from the zones, Malstat assay reagents are added for colour development, proportional to the amount of captured PfLDH. ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04187-6.
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Flanagan SP, Fogel R, Edkins AL, Ho LSJ, Limson J. Nonspecific nuclear uptake of anti-MUC1 aptamers by dead cells: the role of cell viability monitoring in aptamer targeting of membrane-bound protein cancer biomarkers. Anal Methods 2021; 13:1191-1203. [PMID: 33605950 DOI: 10.1039/d0ay01878c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Most aptamers targeting cell-expressed antigens are intended for in vivo application, however, these sequences are commonly generated in vitro against synthetic oligopeptide epitopes or recombinant proteins. As these in vitro analogues frequently do not mimic the in vivo target within an endogenous environment, the evolved aptamers are often prone to nonspecific binding. The presence of dead cells and cellular debris further complicate aptamer targeting, due to their high nonspecific affinities to single-stranded DNA. Despite these known limitations, assessment of cell viability and/or the removal of dead cells is rarely applied as part of the methodology during in vivo testing of aptamer binding. Furthermore, the extent and route(s) by which dead cells uptake existing aptamers remains to be determined in the literature. For this purpose, the previously reported aptamer sequences 5TR1, 5TR4, 5TRG2 and S22 - enriched against the MUC1 tumour marker of the mucin glycoprotein family - were used as model sequences to evaluate the influence of cell viability and the presence of nontarget cell-expressed protein on aptamer binding to the MUC1 expressing human cancer cell lines MCF-7, Hs578T, SW480, and SW620. From fluorescence microscopy analysis, all tested aptamers demonstrated extensive nonspecific uptake within the nuclei of dead cells with compromised membrane integrities. Using fluorescent-activated cell sorting (FACS), the inclusion of excess double-stranded DNA as a blocking agent showed no effect on nonspecific aptamer uptake by dead cells. Further nonspecific binding to cell-membrane bound and intracellular protein was evident for each aptamer sequence, as assessed by southwestern blotting and FACS. These factors likely contributed to the ∼120-fold greater binding response of the 5TR1 aptamer to dead MCF-7 cells over equivalent live cell populations. The identification of dead cells and cellular debris using viability stains and the subsequent exclusion of these cells from FACS analysis was identified as an essential requirement for the evaluation of aptamer binding specificity to live cell populations of the cancer cell lines MCF-7, Hs578T and SW480. The research findings stress the importance of dead cell uptake and more comprehensive cell viability screening to validate novel aptamer sequences for diagnostic and therapeutic application.
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Fellows T, Ho L, Flanagan S, Fogel R, Ojo D, Limson J. Gold nanoparticle-streptavidin conjugates for rapid and efficient screening of aptamer function in lateral flow sensors using novel CD4-binding aptamers identified through Crossover-SELEX. Analyst 2020; 145:5180-5193. [PMID: 32567629 DOI: 10.1039/d0an00634c] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
To decrease the burden of laborious and reagent-intensive screening of modified aptamers, their binding function requires assessment in assay formats compatible with the end diagnostic application. Here, we report on the use of an alternative and cost-effective approach: a rapid lateral flow assay (LFA) utilising streptavidin-conjugated gold nanoparticles (AuNP) as reporter molecules to screen novel ssDNA aptamers for their ability to detect CD4. Crossover-SELEX was employed to identify CD4-targeting aptamers from a ssDNA library enriched against a recombinant human CD4 protein (hCD4) conjugated to magnetic-beads and to endogenous CD4 expressed by U937 cells. Counter-selection with IgG-conjugated beads and CD4-negative Ramos RA-1 cells was employed. Following SELEX, four sequences (U4, U14, U20 and U26) were selected for candidate screening. Fluorescence confocal microscopy showed comparable localization of the Cy5-labeled aptamer U26, compared to antibodies binding CD4's cytoplasmic domain. Aptamer-hCD4 binding kinetics were evaluated by a qPCR-based magnetic-bead binding assay to unmodified aptamers. U26 exhibited the highest binding affinity (Kd = 2.93 ± 1.03 nM) to hCD4-conjugated beads. Citrate-stabilized gold nanoparticles (mean particle diameter, 10.59 ± 1.81 nm) were functionalized with streptavidin to allow immobilization of biotin-labeled aptamers. Except for U4, the aptamer-gold nanoparticle conjugates (Apt-AuNP) remained stable under physiological conditions with their size (approx. 15 nm) appropriate for use in the LFAs. Lateral-flow based screening was used to evaluate the suitability of the Apt-AuNPs as CD4-detecting reporter molecules by immobilizing hCD4 and flowing the nanoparticle conjugates across the LFA. Using this approach, two novel sequences were identified as being suitable for the detection of hCD4: visual detection at 9 min was obtained using U20 or U26. After 20 min, equivalent colorimetric hCD4 responses were observed between anti-CD4 monoclonal antibody (ΔI = 94.19 ± 3.71), an existing CD4 aptamer F1-62 (ΔI = 90.31 ± 19.31) and U26 (ΔI = 100.14 ± 14.61) LFA's, each demonstrating high specificity to hCD4 compared to IgG. From the above, Crossover-SELEX allowed for the successful identification of ssDNA aptamers able to detect hCD4. Streptavidin-conjugated AuNPs, when bound to candidate aptamers, show potential application here as screening tools for the rapid evaluation of aptamer performance in low-cost lateral flow diagnostics.
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Affiliation(s)
- Tamika Fellows
- Rhodes University Biotechnology Innovation Centre, Grahamstown, Eastern Cape, South Africa.
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John Ho LS, Fogel R, Limson JL. Generation and screening of histamine-specific aptamers for application in a novel impedimetric aptamer-based sensor. Talanta 2020; 208:120474. [DOI: 10.1016/j.talanta.2019.120474] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/11/2019] [Accepted: 10/12/2019] [Indexed: 01/29/2023]
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Daveson AJM, Popp A, Taavela J, Goldstein KE, Isola J, Truitt KE, Mäki M, Anderson RP, Adams A, Andrews J, Behrend C, Brown G, Chen Yi Mei S, Coates A, Daveson A, DiMarino A, Elliott D, Epstein R, Feyen B, Fogel R, Friedenberg K, Gearry R, Gerdis M, Goldstein M, Gupta V, Holmes R, Holtmann G, Idarraga S, James G, King T, Klein T, Kupfer S, Lebwohl B, Lowe J, Murray J, Newton E, Quinn D, Radin D, Ritter T, Stacey H, Strout C, Stubbs R, Thackwray S, Trivedi V, Tye‐Din J, Weber J, Wilson S. Baseline quantitative histology in therapeutics trials reveals villus atrophy in most patients with coeliac disease who appear well controlled on gluten‐free diet. ACTA ACUST UNITED AC 2020. [DOI: 10.1002/ygh2.380] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Alina Popp
- Tampere Centre for Child Health Research Faculty of Medicine and Health Technology Tampere University and Tampere University Hospital Tampere Finland
- University of Medicine and Pharmacy "Carol Davila" and National Institute for Mother and Child Health "Alessandrescu‐Rusescu" Bucharest Romania
| | - Juha Taavela
- Tampere Centre for Child Health Research Faculty of Medicine and Health Technology Tampere University and Tampere University Hospital Tampere Finland
- Department of Internal Medicine Central Finland Central Hospital Jyväskylä Finland
| | | | - Jorma Isola
- Laboratory of Cancer Biology Faculty of Medicine and Health Technology Tampere University Tampere Finland
- Jilab Inc. Tampere Finland
| | | | - Markku Mäki
- Tampere Centre for Child Health Research Faculty of Medicine and Health Technology Tampere University and Tampere University Hospital Tampere Finland
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Kruid J, Fogel R, Limson J. Unsubstituted metallophthalocyanine catalysts for the removal of endocrine disrupting compounds using H 2O 2 as oxidant. Environ Sci Pollut Res Int 2018; 25:32346-32357. [PMID: 30229492 DOI: 10.1007/s11356-018-3215-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/12/2018] [Indexed: 06/08/2023]
Abstract
Advanced oxidation processes have become increasingly important to treat non-biodegradable compounds entering environmental waters. In recent decades, water-soluble metallophthalocyanines have been shown to catalyse H2O2-containing oxidation reactions through the production of unique reactive species, nucleophilic metal-peroxo complexes. Few reports in the literature have examined water insoluble metallophthalocyanines (MPc). The oxidative catalytic activity of water insoluble manganese- and iron-phthalocyanine (MnPc, FePc) at pH 7 has been shown through the decolourisation of methylene blue and removal of bisphenol A. These studies expand on this previous study, exploring the catalytic activity of a range of metallophthalocyanines catalysts under both acidic and neutral conditions. FePc, while only active under neutral conditions, was the best performing catalyst. This activity was significantly improved upon by the addition of acetonitrile as a co-solvent, as well as increasing the ratio of H2O2 to catalyst. MnPc was catalytically active at both pH 3 and 7. FePc and MnPc catalysts showed the ability to remove bisphenol A in the presence of dam water. Reaction rates were reduced for bisphenol A removal with FePc as a catalyst but were unchanged in the presence of MnPc. The removal of 17β-estradiol, estrone, and coumestrol was successfully demonstrated, with greater than 96% removal of all tested EDC's achieved. This is the first reported study showing the removal of the phytoestrogen, coumestrol. Even though considerably lower concentrations of costly catalysts and oxidation reagents were used in our work, the removal extent of EDC's by the MPc-catalysed oxidation reactions achieved here compares favourably with literature.
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Affiliation(s)
- Jan Kruid
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, South Africa
| | - Ronen Fogel
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, South Africa
| | - Janice Limson
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, South Africa.
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Frith KA, Fogel R, Goldring JPD, Krause RGE, Khati M, Hoppe H, Cromhout ME, Jiwaji M, Limson JL. Towards development of aptamers that specifically bind to lactate dehydrogenase of Plasmodium falciparum through epitopic targeting. Malar J 2018; 17:191. [PMID: 29724225 PMCID: PMC5934816 DOI: 10.1186/s12936-018-2336-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/26/2018] [Indexed: 11/19/2022] Open
Abstract
Background Early detection is crucial for the effective treatment of malaria, particularly in those cases infected with Plasmodium falciparum. There is a need for diagnostic devices with the capacity to distinguish P. falciparum from other strains of malaria. Here, aptamers generated against targeted species-specific epitopes of P. falciparum lactate dehydrogenase (rPfLDH) are described. Results Two classes of aptamers bearing high binding affinity and specificity for recombinant P. falciparum lactate dehydrogenase (rPfLDH) and P. falciparum-specific lactate dehydrogenase epitopic oligopeptide (LDHp) were separately generated. Structurally-relevant moieties with particular consensus sequences (GGTAG and GGCG) were found in aptamers reported here and previously published, confirming their importance in recognition of the target, while novel moieties particular to this work (ATTAT and poly-A stretches) were identified. Aptamers with diagnostically-supportive functions were synthesized, prime examples of which are the aptamers designated as LDHp 1, LDHp 11 and rLDH 4 and rLDH 15 in work presented herein. Of the sampled aptamers raised against the recombinant protein, rLDH 4 showed the highest binding to the target rPfLDH in the ELONA assay, with both rLDH 4 and rLDH 15 indicating an ability to discriminate between rPfLDH and rPvLDH. LDHp 11 was generated against a peptide selected as a unique P. falciparum LDH peptide. The aptamer, LDHp 11, like antibodies against the same peptide, only detected rPfLDH and discriminated between rPfLDH and rPvLDH. This was supported by affinity binding experiments where only aptamers generated against a unique species-specific epitope showed an ability to preferentially bind to rPfLDH relative to rPvLDH rather than those generated against the whole recombinant protein. In addition, rLDH 4 and LDHp 11 demonstrated in situ binding to P. falciparum cells during confocal microscopy. Conclusions The utilization and application of LDHp 11, an aptamer generated against a unique species-specific epitope of P. falciparum LDH indicated the ability to discriminate between recombinant P. falciparum and Plasmodium vivax LDH. This aptamer holds promise as a biorecognition element in malaria diagnostic devices for the detection, and differentiation, of P. falciparum and P. vivax malaria infections. This study paves the way to explore aptamer generation against targeted species-specific epitopes of other Plasmodium species.
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Affiliation(s)
- Kelly-Anne Frith
- Biotechnology Innovation Centre, Rhodes University, P.O. Box 94, Grahamstown, 6140, Eastern Cape, South Africa
| | - Ronen Fogel
- Biotechnology Innovation Centre, Rhodes University, P.O. Box 94, Grahamstown, 6140, Eastern Cape, South Africa
| | - J P Dean Goldring
- Department of Biochemistry, Genetics and Microbiology, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, KwaZulu-Natal, South Africa
| | - Robert G E Krause
- Department of Biochemistry, Genetics and Microbiology, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, KwaZulu-Natal, South Africa
| | - Makobetsa Khati
- Emerging Health Technologies Platform, Biosciences Division, Council for Scientific and Industrial Research, PO Box 395, Pretoria, 0001, Gauteng, South Africa
| | - Heinrich Hoppe
- Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown, 6140, Eastern Cape, South Africa
| | - Mary E Cromhout
- Biotechnology Innovation Centre, Rhodes University, P.O. Box 94, Grahamstown, 6140, Eastern Cape, South Africa
| | - Meesbah Jiwaji
- Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown, 6140, Eastern Cape, South Africa
| | - Janice L Limson
- Biotechnology Innovation Centre, Rhodes University, P.O. Box 94, Grahamstown, 6140, Eastern Cape, South Africa.
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Vogelmeier C, Wedzicha J, Donohue J, Fucile S, Yadao A, Ayers T, Thach C, FowlerTaylor A, Fogel R, Patalano F, Banerji D. Once-daily indacaterol/glycopyrronium reduces the rate and risk of moderate or severe exacerbations compared with twice-daily salmeterol/fluticasone in a subset of gold froup D COPD patients with a history of >= 2 exacerbations or 1 hospitalization: the FLAME study. Pneumologie 2018. [DOI: 10.1055/s-0037-1619355] [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: 10/28/2022]
Affiliation(s)
- C Vogelmeier
- Department of Medicine, Pulmonary and Critical Care Medicine, University Medical Centre Gießen and Marburg, Phillips-University Marburg; Member of the German Centre for Lung Research (DZL)
| | - J Wedzicha
- National Heart and Lung Institute-Imperial College London
| | - J Donohue
- Department of Medicine, University of North Carolina
| | - S Fucile
- Novartis Pharmaceuticals Corporation, East Hanover, USA
| | - A Yadao
- Novartis Pharmaceuticals Corporation, East Hanover, USA
| | - T Ayers
- Novartis Pharmaceuticals Corporation, East Hanover, USA
| | - C Thach
- Novartis Pharmaceuticals Corporation, East Hanover, USA
| | | | - R Fogel
- Novartis Pharmaceuticals Corporation, East Hanover, USA
| | | | - D Banerji
- Novartis Pharmaceuticals Corporation, East Hanover, USA
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Greulich T, Kostikas K, Gaga M, Aalamian-Mattheis M, Patalano F, Nunez X, Pagano VA, Clemens A, Fogel R, Vogelmeier C. Indacaterol/glycopyrronium (IND/GLY) reduces the risk of clinically important deterioration (CID) in patients with moderate COPD: Results from the CRYSTAL study. Pneumologie 2018. [DOI: 10.1055/s-0037-1619342] [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: 10/28/2022]
Affiliation(s)
- T Greulich
- Schwerpunkt Pneumologie, Klinik für Innere Medizin, Universitätsklinikum Gießen und Marburg, Standort Marburg
| | | | - M Gaga
- 7th Respiratory Medicine Department, Athens Chest Hospital Sotiria
| | | | | | | | | | | | - R Fogel
- Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA
| | - C Vogelmeier
- Pulmonary and Critical Care Medicine, Philipps-Universität Marburg
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Kruid J, Fogel R, Limson JL. Quantitative methylene blue decolourisation assays as rapid screening tools for assessing the efficiency of catalytic reactions. Chemosphere 2017; 175:247-252. [PMID: 28226278 DOI: 10.1016/j.chemosphere.2017.02.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 01/20/2017] [Accepted: 02/08/2017] [Indexed: 06/06/2023]
Abstract
Identifying the most efficient oxidation process to achieve maximum removal of a target pollutant compound forms the subject of much research. There exists a need to develop rapid screening tools to support research in this area. In this work we report on the development of a quantitative assay as a means for identifying catalysts capable of decolourising methylene blue through the generation of oxidising species from hydrogen peroxide. Here, a previously described methylene blue test strip method was repurposed as a quantitative, aqueous-based spectrophotometric assay. From amongst a selection of metal salts and metallophthalocyanine complexes, monitoring of the decolourisation of the cationic dye methylene blue (via Fenton-like and non-Fenton oxidation reactions) by the assay identified the following to be suitable oxidation catalysts: CuSO4 (a Fenton-like catalyst), iron(II)phthalocyanine (a non-Fenton oxidation catalyst), as well as manganese(II) phthalocyanine. The applicability of the method was examined for the removal of bisphenol A (BPA), as measured by HPLC, during parallel oxidation experiments. The order of catalytic activity was identified as FePc > MnPc > CuSO4 for both BPA and MB. The quantitative MB decolourisation assay may offer a rapid method for screening a wide range of potential catalysts for oxidation processes.
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Affiliation(s)
- Jan Kruid
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, 6140, South Africa
| | - Ronen Fogel
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, 6140, South Africa.
| | - Janice Leigh Limson
- Biotechnology Innovation Centre, Rhodes University, Grahamstown, 6140, South Africa
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Kornmann O, Anzueto A, Kostikas K, Mezzi K, Fucile S, Bader G, Shen S, Banerji D, Fogel R. Indacaterol/Glycopyrronium (IND/GLY) verzögert eine klinisch relevante Verschlechterung im Vergleich zu Salmeterol/Fluticason (SFC) bei symptomatischen COPD Patienten: zusammenfassende Analyse der LANTERN/ILLUMINATE Studien. Pneumologie 2017. [DOI: 10.1055/s-0037-1598542] [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: 10/20/2022]
Affiliation(s)
- O Kornmann
- Institut für Klinische Forschung Pneumologie
| | - A Anzueto
- University of Texas Health Science Center and South Texas Veterans Healthcare System
| | | | - K Mezzi
- Respiratory, Novartis Pharma AG
| | - S Fucile
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - G Bader
- Respiratory, Novartis Pharma AG
| | - S Shen
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - D Banerji
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - R Fogel
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
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Vogelmeier C, Wedzicha JA, Chapman KR, Ayers T, FowlerTaylor A, Thach C, Olsson P, Shrinivasan A, Fogel R, Patalano F, Banerji D. Einmal täglich Indacaterol/Glycopyrronium (IND/GLY) reduziert COPD Exazerbationen im Vergleich zu zweimal täglich Salmeterol/Fluticason (SFC) in COPD Patienten mit mindestens einer Exazerbation im Vorjahr: die FLAME Studie. Pneumologie 2017. [DOI: 10.1055/s-0037-1598302] [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: 10/20/2022]
Affiliation(s)
- C Vogelmeier
- Innere Medizin, Schwerpunkt Pneumologie, Universitätsklinikum Gießen und Marburg, Standort Marburg
| | - JA Wedzicha
- National Heart and Lung Institute, Imperial College London
| | - KR Chapman
- Department of Medicine, Asthma and Airway Centre, University Health Network, University of Toronto
| | - T Ayers
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - A FowlerTaylor
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - C Thach
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | | | | | - R Fogel
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | | | - D Banerji
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
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Herth FJF, Patalano F, Wedzicha JA, Vestbo J, FowlerTaylor A, Ayers T, Thach C, Ruparelia N, Fogel R, Banerji D. Indacaterol/Glycopyrronium (IND/GLY) reduziert Exazerbationen und verbessert die Lungenfunktion im Vergleich zu Salmeterol/Fluticason (SFC) bei Patienten mit und ohne vorhergehender ICS Therapie: die FLAME Studie. Pneumologie 2017. [DOI: 10.1055/s-0037-1598405] [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: 10/20/2022]
Affiliation(s)
- FJF Herth
- Thoraxklinik, University of Heidelberg; Departent of Pneumology and Critical Care Medicine; Translational Lung Research Center (Tlrc) Heidelberg, Member of the German Center for Lung Research (Dzl), Germany
| | | | - JA Wedzicha
- National Heart and Lung Institute, Imperial College London
| | - J Vestbo
- Respiratory Research Group; Manchester Academic Health Sciences Centre
| | - A FowlerTaylor
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - T Ayers
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - C Thach
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - N Ruparelia
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - R Fogel
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
| | - D Banerji
- Respiratory, Novartis Pharmaceuticals Corporation, East Hanover
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17
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Kostikas K, Tsiligianni I, Fucile S, Mezzi K, Shen S, Banerji D, Fogel R. P60 Effect of Indacaterol/Glycopyrronium (IND/GLY) on patient-reported outcomes in men and women with COPD: a pooled analysis from the ignite programme. Thorax 2016. [DOI: 10.1136/thoraxjnl-2016-209333.203] [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: 11/03/2022]
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18
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Sandborn WJ, Bhandari BR, Fogel R, Onken J, Yen E, Zhao X, Jiang Z, Ge D, Xin Y, Ye Z, French D, Silverman JA, Kanwar B, Subramanian GM, McHutchison JG, Lee SD, Shackelton LM, Pai RK, Levesque BG, Feagan BG. Randomised clinical trial: a phase 1, dose-ranging study of the anti-matrix metalloproteinase-9 monoclonal antibody GS-5745 versus placebo for ulcerative colitis. Aliment Pharmacol Ther 2016; 44:157-69. [PMID: 27218676 PMCID: PMC5089609 DOI: 10.1111/apt.13653] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 03/26/2016] [Accepted: 04/16/2016] [Indexed: 12/15/2022]
Abstract
BACKGROUND Matrix metalloproteinase-9 is a proteolytic enzyme whose expression is increased in ulcerative colitis. AIM To evaluate the safety and efficacy of GS-5745, a fully humanised anti-matrix metalloproteinase-9 monoclonal antibody, in moderately-to-severely active ulcerative colitis. METHODS We randomised 74 patients with ulcerative colitis to treatment with single or multiple ascending intravenous or subcutaneous doses of GS-5745 or placebo. Multiple-dose cohorts received either IV infusions (0.3, 1.0, 2.5 or 5.0 mg/kg GS-5745 or placebo) every 2 weeks (three total IV infusions) or five weekly SC injections (150 mg GS-5745 or placebo). The primary outcomes were the safety, tolerability and pharmacokinetics of escalating single and multiple doses of GS-5745. Exploratory analyses in the multiple-dose cohorts included clinical response (≥3 points or 30% decrease from baseline in Mayo Clinic score and ≥1 point decrease in the rectal bleeding subscore or a rectal bleeding subscore ≤1) and clinical remission (a complete Mayo Clinic score ≤2 with no subscore >1) at Day 36. Biological effects associated with a clinical response to GS-5745 were explored using histological and molecular approaches. RESULTS Twenty-three of the 42 patients (55%) receiving multiple doses of GS-5745 had adverse events, compared with 5/8 patients (63%) receiving placebo. GS-5745 showed target-mediated drug disposition, approximately dose-proportional increases in maximum plasma concentration and more than dose-proportional increases in the area under the plasma drug concentration-time curve. Clinical response occurred in 18/42 patients (43%) receiving GS-5745 compared with 1/8 patients (13%) receiving placebo. Clinical remission occurred in 6/42 patients (14%) receiving GS-5745 and 0/8 (0%) receiving placebo. Patients with a clinical response to GS-5745 had reductions in matrix metalloproteinase-9 tissue levels (mean 48.9% decrease from baseline compared with a mean 18.5% increase in nonresponders, P = 0.008) significant improvements in histopathology scores (confirmed with three separate histological disease activity indices), as well as changes in colonic gene expression that were consistent with reduced inflammation. CONCLUSION This phase 1 trial provides preliminary evidence for the safety and therapeutic potential of GS-5745 in the treatment of ulcerative colitis.
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Affiliation(s)
- W. J. Sandborn
- Robarts Clinical TrialsUniversity of Western OntarioLondonONCanada,University of CaliforniaSan DiegoCAUSA
| | | | - R. Fogel
- Clinical Research Institute of MichiganLLCChesterfieldMIUSA
| | - J. Onken
- Duke University Medical CenterDurhamNCUSA
| | - E. Yen
- Gilead Sciences, Inc.Foster CityCAUSA
| | - X. Zhao
- Gilead Sciences, Inc.Foster CityCAUSA
| | - Z. Jiang
- Gilead Sciences, Inc.Foster CityCAUSA
| | - D. Ge
- Gilead Sciences, Inc.Foster CityCAUSA
| | - Y. Xin
- Gilead Sciences, Inc.Foster CityCAUSA
| | - Z. Ye
- Gilead Sciences, Inc.Foster CityCAUSA
| | - D. French
- Gilead Sciences, Inc.Foster CityCAUSA
| | | | - B. Kanwar
- Gilead Sciences, Inc.Foster CityCAUSA
| | | | | | - S. D. Lee
- University of WashingtonSeattleWAUSA
| | - L. M. Shackelton
- Robarts Clinical TrialsUniversity of Western OntarioLondonONCanada
| | | | - B. G. Levesque
- Robarts Clinical TrialsUniversity of Western OntarioLondonONCanada
| | - B. G. Feagan
- Robarts Clinical TrialsUniversity of Western OntarioLondonONCanada,Department of MedicineUniversity of Western OntarioLondonONCanada,Department of Epidemiology and BiostatisticsUniversity of Western OntarioLondonONCanada
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Greulich T, Vogelmeier C, Zhong N, Mezzi K, Fogel R, Banerji D. Einmal-täglich Indacaterol/Glycopyrronium verbessert Lungenfunktion und Gesundheitsstatus versus zweimal-täglich Salmeterol/Fluticason bei symptomatischen GOLD B und GOLD D COPD Patienten: LANTERN/ILLUMINATE gepoolte Analyse. Pneumologie 2016. [DOI: 10.1055/s-0036-1572089] [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: 10/22/2022]
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20
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Greulich T, Wedzicha W, Price D, Mezzi K, Fogel R, Banerji D. Vergleich der Fixdosiskombinationen Indacaterol/Glycopyrronium (IND/GLY) und Salmeterol/Fluticason (SFC) in Bezug auf Exazerbationen unter Berücksichtigung der Baseline-Blut-Eosinophilen: eine gepoolte Analyse der LANTERN und ILLUMINATE Studien. Pneumologie 2016. [DOI: 10.1055/s-0036-1572136] [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: 10/22/2022]
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21
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Ficker JH, Wedzicha W, Mezzi K, Fogel R, Banerji D. Baseline-Symptom-Scores und zukünftiges Risiko für schwere Exazerbationen: die SPARK Studie. Pneumologie 2016. [DOI: 10.1055/s-0036-1572088] [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: 10/22/2022]
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22
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Fogel R, Limson J. Developing Biosensors in Developing Countries: South Africa as a Case Study. Biosensors (Basel) 2016; 6:bios6010005. [PMID: 26848700 PMCID: PMC4810397 DOI: 10.3390/bios6010005] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 01/23/2016] [Accepted: 01/27/2016] [Indexed: 12/14/2022]
Abstract
A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors.
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Affiliation(s)
- Ronen Fogel
- Biotechnology Innovation Centre, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa.
| | - Janice Limson
- Biotechnology Innovation Centre, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa.
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Welte T, Dahl R, Buhl R, Mezzi K, Schubert-Tennigkeit AA, Chen H, Banerji D, Fogel R. Kardio- und cerebrovaskuläre Sicherheit von QVA149 bei Patienten mit moderater bis sehr schwerer COPD: Eine gepoolte Analyse. Pneumologie 2015. [DOI: 10.1055/s-0035-1544788] [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: 10/24/2022]
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Ficker JH, Wedzicha W, D'Urzo A, Mezzi K, Chen H, Banerji D, Fogel R. QVA149 zeigt signifikante Verbesserungen in Lungenfunktion und Gesundheitsstatus sowie gute Verträglichkeit gegenüber Glycopyrronium und Tiotropium bei Patienten mit schwerer COPD: Die SPARK-Studie. Pneumologie 2015. [DOI: 10.1055/s-0035-1544794] [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: 10/24/2022]
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25
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Ficker JH, Wedzicha W, Decramer MLA, Olsson P, Chen H, Fogel R, Banerji D. QVA149 reduziert das Risiko moderater bis schwerer Exazerbationen im Vergleich zu unverblindetem Tiotropium bei Patienten mit schwerer COPD: Die SPARK-Studie. Pneumologie 2015. [DOI: 10.1055/s-0035-1544793] [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: 10/24/2022]
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26
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Kruid J, Fogel R, Limson J. Voltammetric investigation of complex growth media at a bare glassy carbon electrode: A case study of oxytetracycline. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.08.188] [Citation(s) in RCA: 4] [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: 10/26/2022]
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27
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Fogel R, Sridharan S, Li C, Bradley J, Riese R, Labadie R, Menon S, Gupta P, Krishnasawami S, Beebe J. AB0724 Safety, pharmacokinetics, and pharmacodynamics of a human anti-IL6 monoclonal antibody PF-04236921 in healthy subjects. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2012-eular.724] [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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Fogel R, Limson JL. Electrochemically Predicting Phenolic Substrates’ Suitability for Detection by Amperometric Laccase Biosensors. ELECTROANAL 2013. [DOI: 10.1002/elan.201200642] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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29
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Edwards SL, Fogel R, Mtambanengwe K, Togo C, Laubscher R, Limson JL. Metallophthalocyanine/carbon nanotube hybrids: extending applications to microbial fuel cells. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424612501027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pioneering work by Nyokong and others have highlighted the potential benefits for improved electron transfer processes and catalysis of hybrid configurations of metallophthalocyanines with carbon nanotubes. Here we examine the practical application of such hybrid configurations in an Enterobacter cloacae microbial fuel cell. Electrochemical investigations at glassy carbon electrodes (GCEs) showed that FePc and FePc :multiwalled carbon nanotube (MWCNT) hybrid surface modifications display significant oxygen reduction reaction electrocatalytic properties compared to either MWCNT-modified or bare GCE surfaces throughout acidic- to moderately-alkaline pHs. Significant stabilization of the current response at FePc :MWCNT surfaces are notable throughout the pH range, compared to GCE surfaces modified with FePc alone. Corresponding results were obtained for surface modifications of bare carbon paper (BCP) cathodes in a microbial fuel cell where power density increases were observed in the order: Pt > FePc :MWCNT > FePc > MWCNT > BCP. A synergistic combination of simple treatments such as increased ionic strength (300 mM NaCl ), temperature (35 °C), and agitation of the anode chamber in this MFC configuration increased the power density to 2.5 times greater than that achieved at platinised cathode configurations under non-optimised conditions, achieving peak power densities of 212 mW.m-2. The long-term stability of the MFC was assessed over 55 days. Surprisingly, the majority of signal loss over extended MFC operation was attributed, in this study, to fouling of the Nafion® PEM membrane rather than either leaching/fouling of the catalysts from the electrodes or nutrient depletion in the anode over the time periods examined.
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Affiliation(s)
- Sean L. Edwards
- Department of Biochemistry, Microbiology & Biotechnology, South Africa
| | - Ronen Fogel
- Department of Biochemistry, Microbiology & Biotechnology, South Africa
| | | | - Chamunorwa Togo
- Department of Biochemistry, Microbiology & Biotechnology, South Africa
| | - Richard Laubscher
- Institute for Environmental Biotechnology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
| | - Janice L. Limson
- Department of Biochemistry, Microbiology & Biotechnology, South Africa
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Niland MJ, Fogel R, Flanagan SP, Limson JL. Towards Normalising Variability in Current Responses at Glassy Carbon Electrodes Using Double Layer Capacitance; a Case Study of Citrinin. ELECTROANAL 2012. [DOI: 10.1002/elan.201100645] [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: 11/11/2022]
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Fogel R, Limson JL. Probing fundamental film parameters of immobilized enzymes--towards enhanced biosensor performance. Part I--QCM-D mass and rheological measurements. Enzyme Microb Technol 2011; 49:146-52. [PMID: 22112401 DOI: 10.1016/j.enzmictec.2011.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 05/15/2011] [Accepted: 05/22/2011] [Indexed: 11/18/2022]
Abstract
Enzyme immobilization is an ever-growing research-area for both analytical and industrial applications. Of critical importance in this area are the effects of immobilization procedures upon the functionality of the immobilized biomolecules. Both beneficial and detrimental effects can be conferred through the selection and tuning of the immobilization procedure. Quartz-crystal microbalance with dissipation (QCM-D) has been previously used to great effect in tracking alterations to thin films of biomolecules immobilized onto quartz transducers. In this study, we investigate the ability of QCM-D to track and monitor film parameters of a monolayer of laccase immobilized on a series of self-assembled monolayers (SAMs), differing in lateral density of binding residues on the SAM and height of the SAM from the quartz surface. Both mass gains and rheological parameters for these varying surfaces were measured and trends later compared to the apparent enzyme kinetics of the immobilized laccase films, assessed electroanalytically (Paper II in this two part study). For covalent attachment of proteins, both shear and viscosity were increased relative to physically adsorbed proteins. An increase in lateral density of protein-binding surface of the SAM components was shown to increase the shear/viscosity of the resultant film while an increase in distance from the electrode (through incorporation of lysine linkers) was shown to decrease the shear/viscosity while simultaneously increasing the wet mass gain of the films. Shear and viscosity may be indicative of both enzyme denaturation and increased lateral protein packing within the film structure hence it is assumed that less distortion occurs with the inclusion of linkers which allow for more optimal protein immobilization.
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Affiliation(s)
- R Fogel
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown, South Africa
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Fogel R, Limson JL. Probing fundamental film parameters of immobilized enzymes--towards enhanced biosensor performance. Part II-Electroanalytical estimation of immobilized enzyme performance. Enzyme Microb Technol 2011; 49:153-9. [PMID: 22112402 DOI: 10.1016/j.enzmictec.2011.05.004] [Citation(s) in RCA: 8] [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] [Received: 07/14/2010] [Revised: 02/17/2011] [Accepted: 05/07/2011] [Indexed: 11/17/2022]
Abstract
The method of immobilization of a protein has a great influence on the overall conformation, and hence, functioning of the protein. Thus, a greater understanding of the events undergone by the protein during immobilization is key to manipulating the immobilization method to produce a strategy that influences the advantages of immobilization while minimizing their disadvantages in biosensor design. In this, the second paper of a two-part series, we have assessed the kinetic parameters of thin-film laccase monolayers, covalently attached to SAMs differing in spacer-arm length and lateral density of spacer arms. This was achieved using chronoamperometry and an electroactive product (p-benzoquinone), which was modeled in a non-linear regressional fashion to extract the relevant parameters. Finally, comparisons between the kinetic parameters presented in this paper and the rheological parameters of laccase monolayers immobilized in the same manner (Part I of this two paper series) were performed. Improvements in the maximal enzyme-catalysed current, i(max), the apparent Michaelis-Menten constant, K(m) and the apparent biosensor sensitivity were noted for most of the surfaces with increasing linker length. Decreasing the lateral density of the spacer-arms brought about a general improvement in these parameters, which is attributed to the decrease in multiple points of immobilization undergone by functional proteins. Finally, comparisons between rheological data and kinetics data showed that the degree of viscosity exhibited by protein films has a negative influence on attached protein layers, while enhanced protein hydration levels (assessed piezoelectrically from data obtained in Paper 1) has a positive effect on those surfaces comprising rigidly bound protein layers.
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Affiliation(s)
- R Fogel
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown, South Africa
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Dairam A, Fogel R, Daya S, Limson JL. Antioxidant and iron-binding properties of curcumin, capsaicin, and S-allylcysteine reduce oxidative stress in rat brain homogenate. J Agric Food Chem 2008; 56:3350-3356. [PMID: 18422331 DOI: 10.1021/jf0734931] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Research demonstrates that antioxidants and metal chelators may be of beneficial use in the treatment of neurodegenerative diseases, such as Alzheimer's disease (AD). This study investigated the antioxidant and metal-binding properties of curcumin, capsaicin, and S-allylcysteine, which are major components found in commonly used dietary spice ingredients turmeric, chilli, and garlic, respectively. The DPPH assay demonstrates that these compounds readily scavenge free radicals. These compounds significantly curtail iron- (Fe2+) and quinolinic acid (QA)-induced lipid peroxidation and potently scavenge the superoxide anion generated by 1 mM cyanide in rat brain homogenate. The ferrozine assay was used to measure the extent of Fe2+ chelation, and electrochemistry was employed to measure the Fe3+ binding activity of curcumin, capsaicin, and S-allylcysteine. Both assays demonstrate that these compounds bind Fe2+ and Fe3+ and prevent the redox cycling of iron, suggesting that this may be an additional method through which these agents reduce Fe2+-induced lipid peroxidation. This study demonstrates the antioxidant and metal-binding properties of these spice ingredients, and it is hereby postulate that these compounds have important implications in the prevention or treatment of neurodegenerative diseases such as AD.
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Affiliation(s)
- Amichand Dairam
- Department of Biochemistry, Microbiology and Biotechnology and Faculty of Pharmacy, Rhodes University, PO Box 94, Grahamstown, South Africa
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Fogel R, Mashazi P, Nyokong T, Limson J. Critical assessment of the Quartz Crystal Microbalance with Dissipation as an analytical tool for biosensor development and fundamental studies: Metallophthalocyanine–glucose oxidase biocomposite sensors. Biosens Bioelectron 2007; 23:95-101. [PMID: 17466508 DOI: 10.1016/j.bios.2007.03.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [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: 12/15/2006] [Revised: 03/13/2007] [Accepted: 03/22/2007] [Indexed: 10/23/2022]
Abstract
One of the challenges in electrochemical biosensor design is gaining a fundamental knowledge of the processes underlying immobilisation of the molecules onto the electrode surface. This is of particular importance in biocomposite sensors where concerns have arisen as to the nature of the interaction between the biological and synthetic molecules immobilised. We examined the use of the Quartz Crystal Microbalance with Dissipation (QCM-D) as a tool for fundamental analyses of a model sensor constructed by the immobilisation of cobalt(II) phthalocyanine (TCACoPc) and glucose oxidase (GOx) onto a gold-quartz electrode (electrode surface) for the enhanced detection of glucose. The model sensor was constructed in aqueous phase and covalently linked the gold surface to the TCACoPc, and the TCACoPc to the GOx, using the QCM-D. The aqueous metallophthalocyanine (MPc) formed a multi-layer over the surface of the electrode, which could be removed to leave a monolayer with a mass loading that compared favourably to the theoretical value expected. Analysis of frequency and dissipation plots indicated covalent attachment of glucose oxidase onto the metallophthalocyanine layer. The amount of GOx bound using the model system compared favourably to calculations derived from the maximal amperometric functioning of the electrochemical sensor (examined in previously-published literature, Mashazi, P.N., Ozoemena, K.I., Nyokong, T., 2006. Electrochim. Acta 52, 177-186), but not to theoretical values derived from dimensions of GOx as established by crystallography. The strength of the binding of the GOx film with the TCACoPc layer was tested by using 2% SDS as a denaturant/surfactant, and the GOx film was not found to be significantly affected by exposure to this. This paper thus showed that QCM-D can be used in order to model essential processes and interactions that dictate the functional parameters of a biosensor.
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Affiliation(s)
- R Fogel
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, South Africa
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Brimecombe RD, Fogel R, Limson JL. Electrochemical monitoring of the biodegradation of 2,4-dimethylaniline. J Agric Food Chem 2006; 54:8799-803. [PMID: 17090125 DOI: 10.1021/jf061951k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
2,4-Dimethylaniline is a recalcitrant degradant of the pesticide amitraz and is also an industrial pollutant which is genotoxic, teratogenic and carcinogenic. The biological degradation of 2,4-dimethylaniline was examined and monitored by cyclic voltammetry. Pseudomonas species isolated from cattle dip tanks initially metabolized 2,4-dimethylaniline by oxidative deamination, following a degradation pathway via a 3-methylcatechol intermediate. The bacteria were capable of utilizing 2,4-dimethylaniline as a nitrogen source and, following deamination, as a carbon source. The formation of the metabolite, 3-methylcatechol, was monitored and confirmed by voltammetric monitoring.
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Affiliation(s)
- R D Brimecombe
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
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Abstract
STUDY OBJECTIVES Obstructive sleep apnea (OSA) is characterized by repetitive pharyngeal collapse during sleep. Several techniques have been proposed to assess the collapsibility of the upper airway in awake humans, but sleep-wake comparisons have rarely been attempted and there are few studies comparing OSA patients to control subjects. We sought to compare two collapsibility measurement techniques between normal and apneic subjects, and between wakefulness and sleep. DESIGN We conducted three studies. First, we examined whether collapsibility assessed by negative pressure pulses (NPPs) during wakefulness reflected values during sleep in 21 normal subjects. Second, we determined in these normal subjects whether collapsibility during sleep assessed by NPPs was predictive of collapsibility measured by inspiratory resistive loading (IRL). Finally, we compared upper-airway collapsibility between apnea patients (n = 22) and normal volunteers (n = 38) during wakefulness by NPPs. SETTING Clinical and research laboratories at the Brigham and Women's Hospital. PARTICIPANTS Two populations of normal subjects (n = 21 and n = 38) and OSA patients (n = 22). MEASUREMENTS AND RESULTS Collapsibility during wakefulness, as measured by NPPs, correlated significantly with collapsibility during sleep (r = 0.62; p = 0.003). There was also a significant correlation between the two measures of collapsibility (IRL and NPP) during sleep (r = 0.53; p = 0.04). Both measures revealed a significant increase in pharyngeal collapsibility during sleep as compared to wakefulness. Finally, apnea patients had significantly greater pharyngeal collapsibility than control subjects during wakefulness (p = 0.017). CONCLUSIONS These data suggest that upper-airway collapsibility measured during wakefulness does provide useful physiologic information about pharyngeal mechanics during sleep and demonstrates clear differences between individuals with and without sleep apnea.
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Affiliation(s)
- A Malhotra
- Sleep Disorders Section, Divisions of Endocrinology and Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02115, USA
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Arrow KJ, Axelrod J, Benacerraf B, Berg P, Bishop JM, Bloembergen N, Brown HC, Cibelli J, Cohen S, Cooper LN, Corey EJ, Cronin JW, Curl R, Dulbecco R, Fischer EH, Fitch VL, Fogel R, Friedman JI, Furchgott RF, Gell-Mann M, Gilbert W, Gilman A, Glaser D, Glashow SL, Green RM, Greengard P, Guillemin R, Hayflick L, Hauptman HA, Heckman JJ, Heeger A, Herschbach D, Hubel DH, Hulse R, Kandel E, Karle J, Klein LR, Kohn W, Kornberg A, Krebs EG, Lanza RP, Laughlin R, Lederman L, Lee DM, Lewis E, Lipscomb W, Marcus RA, McFadden D, Merrifield RB, Merton R, Modigliani F, Molina MJ, Murad F, Nirenberg MW, North DC, Olah GA, Osheroff D, Palade GE, Perl M, Ramsey NF, Richter B, Roberts RJ, Samuelson PA, Schwartz M, Sharp PA, Smalley RE, Smith HO, Solow RM, Stormer H, Taube H, Taylor R, Thomas ED, Tobin J, Tonegawa S, Townes C, Watson JD, Weinberg S, Weller TH, West MD, Wieschaus EF, Wiesel TN, Wilson RW. Nobel laureates' letter to President Bush. Washington Post 2001:A02. [PMID: 12462241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
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Podila PV, Ben-Menachem T, Batra SK, Oruganti N, Posa P, Fogel R. Managing patients with acute, nonvariceal gastrointestinal hemorrhage: development and effectiveness of a clinical care pathway. Am J Gastroenterol 2001; 96:208-19. [PMID: 11197254 DOI: 10.1111/j.1572-0241.2001.03477.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To develop a clinical care pathway for the management of patients with acute upper or lower nonvariceal GI hemorrhage (GIH) who do not require immediate surgical intervention. To test the effectiveness and safety of the pathway in improving the efficiency of care for patients with acute GIH. METHODS A multidisciplinary team developed the evidence-based GIH clinical care pathway by consensus techniques. In a quasiexperimental design, pathway outcomes were measured prospectively during the first 8 months of pathway implementation, and compared to similar time periods in the 2 prior yr. Effectiveness measures were the number of patients <65 yr of age admitted for GIH and the hospital length of stay for all patients. Thirty-day safety outcomes were the rates of recurrent GIH, mortality, and readmission to hospital for any reason. RESULTS Of 368 patients studied after pathway implementation, 81 (22%) were managed as outpatients. The number of admissions for pathway patients <65 yr of age was significantly lower compared to 691 prepathway patients (p < 0.002). Mean length of stay (+/- 95% CI) for pathway inpatients was 3.5 (3.1, 3.9) days, compared to 5.3 (4.9, 5.7) and 4.6 (4.2, 5) days in the 2 prepathway yr, respectively (p < 0.001). Multivariable regression controlling for admission vital signs, comorbid conditions, age, and the etiology of GIH confirmed that admission after pathway implementation was an independent predictor of a reduced length of hospital stay. There were no significant between-year differences in the 30-day rates of recurrent GIH, mortality, or hospital readmission. CONCLUSION A multidisciplinary clinical care pathway may improve the efficiency of caring for patients with acute upper or lower nonvariceal GIH. Decreasing the number of admissions for GIH and reducing the hospital length of stay can be achieved without increasing the number of adverse outcomes.
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Affiliation(s)
- P V Podila
- Division of Gastroenterology, Henry Ford Hospital, Detroit, Michigan 48202, USA
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Prorok PC, Andriole GL, Bresalier RS, Buys SS, Chia D, Crawford ED, Fogel R, Gelmann EP, Gilbert F, Hasson MA, Hayes RB, Johnson CC, Mandel JS, Oberman A, O'Brien B, Oken MM, Rafla S, Reding D, Rutt W, Weissfeld JL, Yokochi L, Gohagan JK. Design of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Control Clin Trials 2000; 21:273S-309S. [PMID: 11189684 DOI: 10.1016/s0197-2456(00)00098-2] [Citation(s) in RCA: 727] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The objectives of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial are to determine in screenees ages 55-74 at entry whether screening with flexible sigmoidoscopy (60-cm sigmoidoscope) can reduce mortality from colorectal cancer, whether screening with chest X-ray can reduce mortality from lung cancer, whether screening men with digital rectal examination (DRE) plus serum prostate-specific antigen (PSA) can reduce mortality from prostate cancer, and whether screening women with CA125 and transvaginal ultrasound (TVU) can reduce mortality from ovarian cancer. Secondary objectives are to assess screening variables other than mortality for each of the interventions including sensitivity, specificity, and positive predictive value; to assess incidence, stage, and survival of cancer cases; and to investigate biologic and/or prognostic characterizations of tumor tissue and biochemical products as intermediate endpoints. The design is a multicenter, two-armed, randomized trial with 37,000 females and 37,000 males in each of the two arms. In the intervention arm, the PSA and CA125 tests are performed at entry, then annually for 5 years. The DRE, TVU, and chest X-ray exams are performed at entry and then annually for 3 years. Sigmoidoscopy is performed at entry and then at the 5-year point. Participants in the control arm follow their usual medical care practices. Participants will be followed for at least 13 years from randomization to ascertain all cancers of the prostate, lung, colorectum, and ovary, as well as deaths from all causes. A pilot phase was undertaken to assess the randomization, screening, and data collection procedures of the trial and to estimate design parameters such as compliance and contamination levels. This paper describes eligibility, consent, and other design features of the trial, randomization and screening procedures, and an outline of the follow-up procedures. Sample-size calculations are reported, and a data analysis plan is presented.
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Affiliation(s)
- P C Prorok
- Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland 20892-7346, USA
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Pillar G, Malhotra A, Fogel R, Beauregard J, Schnall R, White DP. Airway mechanics and ventilation in response to resistive loading during sleep: influence of gender. Am J Respir Crit Care Med 2000; 162:1627-32. [PMID: 11069787 DOI: 10.1164/ajrccm.162.5.2003131] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.8] [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: 11/16/2022] Open
Abstract
The male predominance in obstructive sleep apnea (OSA) is currently poorly understood although differences in pharyngeal airway anatomy and physiology have been proposed. As the response to inspiratory resistive loading (IRL) provides important information on both airway collapsibility (mechanics) and ventilatory control, we compared this respiratory response in eight normal women and eight age and body mass index (BMI)-matched men, during stable nonrapid eye movement (NREM) sleep. Upper airway mechanics, ventilation, plus activation of two dilator muscles (genioglossus [GG] and tensor palatini [TP]) were monitored during basal breathing (BL), followed by four sequentially applied loads (5, 10, 15, 25 cm H(2)O/L/s) for three breaths each. Men developed more severe hypopnea in response to identical applied external loads than did women. At a resistance of 25 cm H(2)O/L/s, VT decreased by 26 +/- 1% in women compared with 44 +/- 1% in men (differences between sexes p < 0.05). Pharyngeal resistance (Rpha) in response to IRL increased significantly more in men than women (37.3 +/- 11.2 cm H(2)O/L/s in men at maximal load, compared with an increase of 6.6 +/- 3.9 cm H(2)O/L/s in women, p < 0.05). Men and women had near identical minute ventilation responses to total load (applied extrinsic plus measured intrinsic), implying no differences in central drive or load response. There were no significant increases in GG or TP activation in response to IRL in either sex. We conclude that normal men are more vulnerable to load-induced hypoventilation than women, due to increased upper airway collapse, which could not be explained by differences in dilator muscle activation. This implies a fundamental difference in the upper airway anatomy and/or tissue characteristics between the two sexes.
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Affiliation(s)
- G Pillar
- Sleep Disorders Section, Divisions of Endocrinology and Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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Abstract
Electrophysiologic and anterograde tract tracing studies have demonstrated that the vagus nerve innervates the duodenum. These studies, however, have provided little information regarding the finer anatomic topography within the vagal complex. In this study, the retrograde neuronal tracers WGA-HRP or DiI, applied to the duodenum, were used to characterize the vagal afferent and efferent innervation of this portion of the gastrointestinal tract. This approach labeled a substantial number of motor neurons in both the medial and lateral columns of the dorsal motor nucleus of the vagus (DMNV). Vagal motor neurons innervating the duodenum were seen across the medial-lateral extent of the DMNV and between 600 microm rostral to obex and 1600 microm caudal to obex. The three branches of the vagus nerve contained efferent fibers to the duodenum. The gastric branch of the vagus nerve was the pathway that connected the majority of DMNV neurons with the duodenum. These neurons were located in the medial and middle thirds of the DMNV. The celiac branch to the duodenum was composed of axons from the majority of lateral column neurons but also contained axons from neurons in the medial column. The hepatic branch of the vagus nerve contained only a small number of cell axons. Some neurons were located medially whereas others were in the lateral third of the duodenum. Although central terminations of vagal primary afferents from the duodenum were not found in previous tract tracing studies, we observed a large number of terminals in the subpostremal/commissural region of the nucleus of the solitary tract. Similar to the motor fibers, most afferent fibers from the duodenum were located in the gastric branch of the vagus nerve, although the hepatic and celiac branches also contained afferent neurons. These results demonstrate that the vagal innervation of the duodenum is unique, being an amalgam of what would be expected following labeling of more proximal and distal portions of the GI tract. The uniqueness of the sensory and motor innervation to the duodenum has implications for hypotheses regarding the organization of vagovagal reflexes controlling gastrointestinal function.
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Affiliation(s)
- X Zhang
- Neurogastroenterology Laboratory, Division of Gastroenterology, Henry Ford Hospital, 2799 W. Grand Blvd., Detroit, MI 48202, USA
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Coughlin P, Kriebel R, Fogel R. New England Journal of Medicine article may be misleading about OMT. J Am Osteopath Assoc 1999; 99:561, 565. [PMID: 10612952] [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: 02/15/2023]
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Zhang X, Fogel R, Renehan WE. Stimulation of the paraventricular nucleus modulates the activity of gut-sensitive neurons in the vagal complex. Am J Physiol 1999; 277:G79-90. [PMID: 10409154 DOI: 10.1152/ajpgi.1999.277.1.g79] [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] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
There is good evidence that stimulation of the lateral hypothalamus excites neurons in the dorsal vagal complex (DVC), but the data regarding the role of the paraventricular nucleus (PVN) in vagal function are less clear. The purpose of this study was to clarify the effect of PVN stimulation on the activity of neurons in the DVC. We utilized extracellular and intracellular neuronal recordings with intracellular injections of a neuronal tracer to label individual, physiologically characterized neurons in the DVC of rats anesthetized with pentobarbital sodium. Most (80%) of the gut-sensitive dorsal motor nucleus of the vagus (DMNV) neurons characterized in this study exhibited a change in activity during electrical stimulation of the PVN. Stimulation of the PVN caused an increase in the spontaneous activity of 59% of the PVN-sensitive DMNV neurons, and the PVN was capable of modulating the response of a small subset of DMNV neurons to gastrointestinal stimuli. This study also demonstrated that the PVN was capable of influencing the activity of neurons in the nucleus of the solitary tract (NST). Electrical stimulation of the PVN decreased the basal activity of 66% of the NST cells that we characterized and altered the gastrointestinal response of a very small subset of NST neurons. It is likely that these interactions play a role in the modulation of a number of gut-related homeostatic processes. Increased or decreased activity in the descending pathway from the PVN to the DVC has the potential to alter ascending satiety signals, modulate vago-vagal reflexes and the cephalic phase of feeding, and affect the absorption of nutrients from the gastrointestinal tract.
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Affiliation(s)
- X Zhang
- Division of Gastroenterology, Henry Ford Health System, Detroit, Michigan 48202, USA
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Abstract
Perfusing the duodenum with acid solutions dramatically reduces gastric motility and acid secretion. We propose that the presence of acid in the proximal small intestine initiates a vagovagal reflex that excites inhibitory neurons in the nucleus of the solitary tract (NST) and reduces the activity of the neurons in the dorsal motor nucleus of the vagus nerve (DMNV). However, results from several investigations suggest that the relevant circuit may not be as simple as we had believed. The present study was designed to address this dilemma by employing intracellular and extracellular recording and intracellular labeling techniques to provide direct information on the activity of neurons in the NST and DMNV during and after intestinal exposure to acid solutions. The results obtained prove that NST and DMNV neurons respond to HCl in the duodenum. In some instances, these neurons were very stimulus specific, although the majority of the cells in our sample (47% of NST neurons and 86% of DMNV neurons) also responded to distension of the stomach and/or duodenum. It is important to note, however, that many of the more broadly responsive neurons in the dorsal vagal complex were able to distinguish between mechanical and chemical stimulation of the gastrointestinal (GI) tract. Most of the NST neurons that responded to duodenal perfusion with HCl were excited by this stimulus. Conversely, activity of most of the DMNV neurons decreased after the onset of the HCl stimulus. These findings verify the existence of a vagovagal reflex pathway initiated by duodenal perfusion with acid. Presumably, this reflex would decrease gastric motility and acid secretion, reducing the amount of acid that enters the duodenum and ultimately protecting the intestinal mucosa.
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Affiliation(s)
- X Zhang
- Division of Gastroenterology, Henry Ford Hospital, Detroit, Michigan 48202, USA
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Fogel R. ICD Implant Does Not Preclude Working Around Industrial Equipment. J Am Coll Cardiol 1998. [DOI: 10.1016/s0735-1097(97)85595-7] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ben-Menachem T, McCarthy BD, Fogel R, Schiffman RM, Patel RV, Zarowitz BJ, Nerenz DR, Bresalier RS. Prophylaxis for stress-related gastrointestinal hemorrhage: a cost effectiveness analysis. Crit Care Med 1996; 24:338-45. [PMID: 8605811 DOI: 10.1097/00003246-199602000-00026] [Citation(s) in RCA: 59] [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: 01/31/2023]
Abstract
OBJECTIVE To assess the cost-effectiveness of prophylaxis for stress-related gastrointestinal hemorrhage in patients admitted to the intensive care unit. DESIGN Decision model of the cost and efficacy of sucralfate and cimetidine, two commonly used drugs for prophylaxis of stress-related hemorrhage. Outcome estimates were based on data from published studies. Cost data were based on cost of medications and costs of treatment protocols at our institutions. MEASUREMENTS AND MAIN RESULTS The marginal cost-effectiveness of prophylaxis, as compare with no prophylaxis, was calculated separately for sucralfate and cimetidine and expressed as cost per bleeding episode averted. An incremental cost-effectiveness analysis was subsequently employed to compare the two agents. Sensitivity analyses of the effects of the major clinical outcomes on the cost per bleeding episode averted were performed. At the base-case assumptions of 6% risk of developing stress-related hemorrhage and 50% risk-reduction due to prophylaxis, the cost of sucralfate was $1,144 per bleeding episode averted. The cost per bleeding episode averted was highly dependent on the risk of hemorrhage and, to a lesser degree, on the efficacy of sucralfate prophylaxis, ranging from a cost per bleeding episode averted of $103,725 for low-risk patients to cost savings for very high-risk patients. The cost per bleeding episode averted increased significantly if the risk of nosocomial pneumonia was included in the analysis. The effect of pneumonia was greater for populations at low risk of hemorrhage. Assuming equal efficacy, the cost per bleeding episode averted of cimetidine was 6.5-fold greater than the cost per bleeding episode averted of sucralfate. CONCLUSIONS The cost of prophylaxis in patients at low risk of stress-related hemorrhage is substantial, and may be prohibitive. Further research is needed to identify patient populations that are at high risk of developing stress-related hemorrhage, and to determine whether prophylaxis increases the risk of nosocomial pneumonia.
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Affiliation(s)
- T Ben-Menachem
- Department of Medicine, Henry Ford Hospital and Health Sciences Center, Detroit, MI, USA
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Fogel R, Pirzada F, Casavant D, Boone J, Bowman A, Steinhaus D, Gilbert M, Vlietstra R, Belott P, Parsonnet V, Tilton G, White M. Initial experience with 1.5-mm2 high impedance, steroid-eluting pacing electrodes. Pacing Clin Electrophysiol 1996; 19:188-96. [PMID: 8834688 DOI: 10.1111/j.1540-8159.1996.tb03310.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
UNLABELLED In this human study, 21 atrial and 62 ventricular 1.5-mm2 unipolar steroid-eluting pacing electrodes were implanted in 64 patients. Pacing thresholds, lead impedance, and sensing measurements were measured via pacemaker telemetry within 24 hours postimplant, and at 1, 2, 3, 4, 6, 12, 24, and 52 weeks. Acute pacing impedances measured via a pacing systems analyzer were 1,039 +/- 292 (atrial) and 1,268 +/- 313 ohms (ventricular). A 10%-15% decline in the mean telemetered atrial and ventricular pacing impedances was observed at 1 week, but thereafter remained stable. Acute pacing thresholds at 0.5 ms were 0.5 +/- 0.3 V (atrial) and 0.4 +/- 0.1 V (ventricular). Filtered P and R wave amplitudes were 3.7 +/- 2.3 mV and 14.9 +/- 5.9 mV, respectively. In 21 patients, no complications related to the atrial electrode were observed. Of 62 patients with ventricular electrodes, 4 patients (6%) experienced complications and required surgical intervention. On these, causative factors included micro-dislodgment (1 patient), and perforation (1 patient). Sudden unexplained exit block occurred late (> 6 weeks) in two patients. In the remainder of patients, pacing thresholds and sensed electrogram amplitudes remained stable throughout the 52-week follow-up period. CONCLUSIONS The present study validates that smaller surface (i.e., 1.5 mm2) steroid-eluting electrode designs offer excellent pacing and sensing performance with significantly higher pacing impedances. Although questions remain as to the cause of late exit block in two patients in this series, this relatively small surface electrode design offers promise toward achieving greater pacing efficiency and a theoretical 13%-16% (minimum) enhancement in permanent pacemaker longevity.
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Affiliation(s)
- R Fogel
- Department of Cardiology, University Hospital, Boston, Massachusetts 02118, USA
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Abstract
The activity of vagal motor neurons is influenced by sensory information transmitted to the brainstem. In particular, there is evidence that distention of the stomach increases activity of motor neurons in the dorsal vagal motor nucleus, whereas distention of the duodenum, small intestine, and colon reduces neuron firing. In this study, we determined 1) the response of vagal motor neurons to distention of the stomach and duodenum and 2) whether the response properties were associated with specific morphological features. Using the single-cell recording and iontophoretic injection technique, we identified four groups of vagal motor neurons affected by gastric and/or duodenal distention. Group 1 neurons responded to either gastric or duodenal stimulation. Neurons in groups 2, 3, and 4 were affected by both gastric and duodenal distention. Group 2 neurons were excited by duodenal distention and were inhibited by gastric distention. Group 3 neurons were inhibited by duodenal distention and were excited by gastric distention. Most neurons belonged to group 4. Neurons in this group were inhibited by both gastric and duodenal distention. Our analyses revealed that the neurons affected by both stimuli had distinctive structural features. Neurons in group 2 had the largest somata, the most dendritic branches, and the greatest cell surface area. Neurons in group 3 were the smallest and had the shortest dendritic length. In addition, we were able to demonstrate that the neurons in group 4 had a smaller total dendritic length and a smaller cell volume than neurons in group 2 and had more dendritic branch segments than neurons in group 3. These results suggest that morphological features are associated with specific response properties of vagal motor neurons.
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Affiliation(s)
- R Fogel
- Division of Gastroenterology, Henry Ford Health Sciences Center, Detroit, Michigan 48202, USA
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49
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Abstract
The activity of vagal motor neurons is influenced by sensory information transmitted to the brainstem. In particular, there is evidence that distention of the stomach increases activity of motor neurons in the dorsal vagal motor nucleus, whereas distention of the duodenum, small intestine, and colon reduces neuron firing. In this study, we determined 1) the response of vagal motor neurons to distention of the stomach and duodenum and 2) whether the response properties were associated with specific morphological features. Using the single-cell recording and iontophoretic injection technique, we identified four groups of vagal motor neurons affected by gastric and/or duodenal distention. Group 1 neurons responded to either gastric or duodenal stimulation. Neurons in groups 2, 3, and 4 were affected by both gastric and duodenal distention. Group 2 neurons were excited by duodenal distention and were inhibited by gastric distention. Group 3 neurons were inhibited by duodenal distention and were excited by gastric distention. Most neurons belonged to group 4. Neurons in this group were inhibited by both gastric and duodenal distention. Our analyses revealed that the neurons affected by both stimuli had distinctive structural features. Neurons in group 2 had the largest somata, the most dendritic branches, and the greatest cell surface area. Neurons in group 3 were the smallest and had the shortest dendritic length. In addition, we were able to demonstrate that the neurons in group 4 had a smaller total dendritic length and a smaller cell volume than neurons in group 2 and had more dendritic branch segments than neurons in group 3. These results suggest that morphological features are associated with specific response properties of vagal motor neurons.
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Affiliation(s)
- R Fogel
- Division of Gastroenterology, Henry Ford Health Sciences Center, Detroit, Michigan 48202, USA
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50
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Zhang X, Fogel R, Renehan WE. Relationships between the morphology and function of gastric- and intestine-sensitive neurons in the nucleus of the solitary tract. J Comp Neurol 1995; 363:37-52. [PMID: 8682936 DOI: 10.1002/cne.903630105] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This study employed single cell recording and intracellular iontophoretic injection techniques to characterize and label gastric- and/or intestine-sensitive neurons in the rat nucleus of the solitary tract (NST). It was possible to divide our sample of NST neurons into three broad groups based on their response to increased intra-gastric and intra-duodenal pressure. Group 1 cells (N = 14) were excited by duodenal distention but were not responsive to gastric stimulation. Most of these intestine-sensitive neurons exhibited a delayed tonic response to the stimulus. Group 2 neurons (N = 13) were excited by gastric distention but were not sensitive to distention of the duodenum. The typical Group 2 neuron evidenced a rapid, phasic response to the distention stimulus. Group 3 neurons (N = 29) responded to both gastric and duodenal stimulation. We found that the Group 2 neurons had greater dendritic length and more dendritic branch segments than the Group 1 or Group 3 neurons. Most of the Group 1 neurons were found in the subpostremal/commissural region of the NST, while the majority of the Group 2 neurons were in the gelatinous subnucleus and a disproportionate number of the Group 3 neurons were located in the medial subnucleus. The results of this investigation demonstrate that 1) there are relationships between the morphology and physiology of distention-sensitive neurons in the NST, and 2) there are distinct functional differences between the gelatinous, medial and commissural subnuclei of this nucleus.
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Affiliation(s)
- X Zhang
- Division of Gastroenterology, Henry Ford Health Sciences Center, Detroit, Michigan 48202, USA
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