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Nicoara SC, Turner NW, Minnikin DE, Lee OYC, O'Sullivan DM, McNerney R, Mutetwa R, Corbett LE, Morgan GH. Development of sample clean up methods for the analysis of Mycobacterium tuberculosis methyl mycocerosate biomarkers in sputum extracts by gas chromatography-mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2015; 986-987:135-42. [PMID: 25728371 PMCID: PMC4381843 DOI: 10.1016/j.jchromb.2015.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 02/05/2015] [Accepted: 02/08/2015] [Indexed: 11/23/2022]
Abstract
We developed a sample clean-up method to detect tuberculosis from sputum by GC–MS. Biomarkers recovered: 64–70% (standards solution), and 36–68% (sputum extracts). Cholesterol removed: 93–98% (standards solution) and 62–92% (sputum extracts). Less cholesterol in the filtered extracts avoids overloading of the analytical system. Analyzing large sample batches will need fewer interruptions for system cleaning.
A proof of principle gas chromatography–mass spectrometry method is presented, in combination with clean up assays, aiming to improve the analysis of methyl mycocerosate tuberculosis biomarkers from sputum. Methyl mycocerosates are generated from the transesterification of phthiocerol dimycocerosates (PDIMs), extracted in petroleum ether from sputum of tuberculosis suspect patients. When a high matrix background is present in the sputum extracts, the identification of the chromatographic peaks corresponding to the methyl derivatives of PDIMs analytes may be hindered by the closely eluting methyl ether of cholesterol, usually an abundant matrix constituent frequently present in sputum samples. The purification procedures involving solid phase extraction (SPE) based methods with both commercial Isolute-Florisil cartridges, and purpose designed molecularly imprinted polymeric materials (MIPs), resulted in cleaner chromatograms, while the mycocerosates are still present. The clean-up performed on solutions of PDIMs and cholesterol standards in petroleum ether show that, depending on the solvent mix and on the type of SPE used, the recovery of PDIMs is between 64 and 70%, whilst most of the cholesterol is removed from the system. When applied to petroleum ether extracts from representative sputum samples, the clean-up procedures resulted in recoveries of 36–68% for PDIMs, allowing some superior detection of the target analytes.
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Affiliation(s)
- Simona C Nicoara
- Centre for Earth, Planetary, Space and Astronomical Research CEPSAR, The Open University, Milton Keynes, UK.
| | - Nicholas W Turner
- Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - David E Minnikin
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, UK
| | - Oona Y-C Lee
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, UK
| | | | - Ruth McNerney
- London School of Hygiene & Tropical Medicine, London, UK
| | - Reggie Mutetwa
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Liz E Corbett
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Geraint H Morgan
- Centre for Earth, Planetary, Space and Astronomical Research CEPSAR, The Open University, Milton Keynes, UK
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Nicoara SC, Minnikin DE, Lee OCY, O'Sullivan DM, McNerney R, Pillinger CT, Wright IP, Morgan GH. Development and optimization of a gas chromatography/mass spectrometry method for the analysis of thermochemolytic degradation products of phthiocerol dimycocerosate waxes found in Mycobacterium tuberculosis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:2374-2382. [PMID: 24097393 PMCID: PMC3824232 DOI: 10.1002/rcm.6694] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/18/2013] [Accepted: 07/20/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE The phthiocerol dimycocerosates (PDIMs) are certain stable and hydrophobic waxes found in the cell membrane of Mycobacterium tuberculosis, bacteria that cause an infectious disease of growing concern worldwide. Previous studies report the analysis of derivatives of the hydrolysed PDIMs from biological samples, following complex extraction and offline derivatization of PDIMs biomarkers, prior to their analysis by gas chromatography/mass spectrometry (GC/MS). METHODS We developed and optimized a GC/MS method based on selected ion monitoring (SIM) to detect the derivatives produced via the thermally assisted hydrolysis and methylation (THM) of the PDIMs from the cell membrane of M. tuberculosis. The extraction of PDIMs from culture is simple, and their thermochemolysis is carried out automatically online, thus avoiding the time-consuming derivatization steps of hydrolysis and esterification, usually performed offline. RESULTS For standard PDIMs in petroleum ether, our optimized method gave an excellent linearity (R(2) = 0.99) at concentrations between 0.172 and 27.5 ng/mL, a good precision (RSD = 11.42%), and a limit of detection (LOD) of 100 pg/mL. For the PDIMs extracted from dilutions of M. tuberculosis culture, the method gave good linearity (R(2) = 0.9685) and an estimated LOD of 400 CFU/mL (CFU = colony forming units) in sterile distilled water. CONCLUSIONS A GC/MS(SIM) method is presented for the rapid and quantitative detection of M. tuberculosis, based on the online thermochemolysis of lipidic biomarkers extracted from the bacterial culture. The method has the potential to be applied in human and veterinary clinical laboratories for the rapid diagnosis of tuberculosis in infected biological samples.
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Affiliation(s)
- Simona C Nicoara
- Department of Physical Sciences, Faculty of Science, The Open UniversityWalton Hall, Milton Keynes, MK7 6AA, UK
- Technical University38 Memorandumului Bld., 400114, Cluj-Napoca, Romania
| | - David E Minnikin
- School of Biosciences, University of BirminghamEdgbaston, Birmingham, B15 2TT, UK
| | - Oona C Y Lee
- School of Biosciences, University of BirminghamEdgbaston, Birmingham, B15 2TT, UK
| | - Denise M O'Sullivan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical MedicineKeppel Street, London, WC1E 7HT, UK
| | - Ruth McNerney
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical MedicineKeppel Street, London, WC1E 7HT, UK
- LGCQueens Road, Teddington, London, TW11 0LY, UK
| | - Collin T Pillinger
- Department of Physical Sciences, Faculty of Science, The Open UniversityWalton Hall, Milton Keynes, MK7 6AA, UK
| | - Ian P Wright
- Department of Physical Sciences, Faculty of Science, The Open UniversityWalton Hall, Milton Keynes, MK7 6AA, UK
| | - Geraint H Morgan
- Department of Physical Sciences, Faculty of Science, The Open UniversityWalton Hall, Milton Keynes, MK7 6AA, UK
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O'Sullivan DM, Nicoara SC, Mutetwa R, Mungofa S, Lee OYC, Minnikin DE, Bardwell MW, Corbett EL, McNerney R, Morgan GH. Detection of Mycobacterium tuberculosis in sputum by gas chromatography-mass spectrometry of methyl mycocerosates released by thermochemolysis. PLoS One 2012; 7:e32836. [PMID: 22403716 PMCID: PMC3293907 DOI: 10.1371/journal.pone.0032836] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 01/31/2012] [Indexed: 11/19/2022] Open
Abstract
Tuberculosis requires rapid diagnosis to prevent further transmission and allow prompt administration of treatment. Current methods for diagnosing pulmonary tuberculosis lack sensitivity are expensive or are extremely slow. The identification of lipids using gas chromatography- electron impact mass spectrometry (GC-EI/MS) could provide an alternative solution. We have studied mycocerosic acid components of the phthiocerol dimycocerosate (PDIM) family of lipids using thermochemolysis GC-EI/MS. To facilitate use of the technology in a routine diagnostic laboratory a simple extraction procedure was employed where PDIMs were extracted from sputum using petroleum ether, a solvent of low polarity. We also investigated a method using methanolic tetramethylammonium hydroxide, which facilitates direct transesterification of acidic components to methyl esters in the inlet of the GC-MS system. This eliminates conventional chemical manipulations allowing rapid and convenient analysis of samples. When applied to an initial set of 40 sputum samples, interpretable results were obtained for 35 samples with a sensitivity relative to culture of 94% (95%CI: 69.2,100) and a specificity of 100% (95%CI: 78.1,100). However, blinded testing of a larger set of 395 sputum samples found the assay to have a sensitivity of 61.3% (95%CI: 54.9,67.3) and a specificity of 70.6% (95%CI: 62.3,77.8) when compared to culture. Using the results obtained we developed an improved set of classification criteria, which when applied in a blinded re-analysis increased the sensitivity and specificity of the assay to 64.9% (95%CI: 58.6,70.8) and 76.2% (95%CI: 68.2,82.8) respectively. Highly variable levels of background signal were observed from individual sputum samples that inhibited interpretation of the data. The diagnostic potential of using thermochemolytic GC-EI/MS of PDIM biomarkers for diagnosis of tuberculosis in sputum has been established; however, further refinements in sample processing are required to enhance the sensitivity and robustness of the test.
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Affiliation(s)
- Denise M. O'Sullivan
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Simona C. Nicoara
- Department of Physical Sciences, The Open University, Milton Keynes, United Kingdom
| | - Reggie Mutetwa
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Stanley Mungofa
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Oona Y-C. Lee
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - David E. Minnikin
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Max W. Bardwell
- Department of Physical Sciences, The Open University, Milton Keynes, United Kingdom
| | - Elizabeth L. Corbett
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Ruth McNerney
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- * E-mail:
| | - Geraint H. Morgan
- Department of Physical Sciences, The Open University, Milton Keynes, United Kingdom
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Isingrini M, Lenoir A, Jaisson P. Preimaginal learning as a basis of colony-brood recognition in the ant Cataglyphis cursor. Proc Natl Acad Sci U S A 2010; 82:8545-7. [PMID: 16593637 PMCID: PMC390953 DOI: 10.1073/pnas.82.24.8545] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In most circumstances, social insects recognize their nestmates. They can discriminate against alien adults and also against alien larvae. Results presented here indicate that the mechanism of colony-brood recognition is acquired in large part during larval life and persists through the metamorphosis into the adult stage. During the first days after emergence of the adult, a weaker form of learning can also occur. These phenomena are discussed in relation to kinship theory. It appears that kin recognition is determined not so much by genetic relatedness as by spatial proximity of the individuals during the early stages of life.
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Affiliation(s)
- M Isingrini
- Laboratoire d'Ethologie et de Psychophysiologie, Faculté des Sciences, Parc de Grandmont 37200 Tours, France
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Redman JE, Shaw MJ, Mallet AI, Santos AL, Roberts CA, Gernaey AM, Minnikin DE. Mycocerosic acid biomarkers for the diagnosis of tuberculosis in the Coimbra Skeletal Collection. Tuberculosis (Edinb) 2009; 89:267-77. [PMID: 19493698 DOI: 10.1016/j.tube.2009.04.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 04/08/2009] [Accepted: 04/10/2009] [Indexed: 10/20/2022]
Abstract
Tuberculosis has been a scourge of humans over many millennia, but questions remain regarding its evolution and epidemiology. Fossil biomarkers, such as DNA and long-chain mycolic acids, can be detected in ancient skeletal and other materials. The phthiocerol dimycocerosate waxes are also robust biomarkers for tuberculosis and sensitive methods are available for the detection of their mycocerosic acid components. The presence of mycocerosic acids was investigated in 49 individuals from the 1837-1936 Coimbra Identified Skeletal Collection (Portugal), half with documentary data indicating tuberculosis as a cause of death. Samples were hydrolysed, acidic components converted to pentafluorobenzyl esters, the non-hydroxylated long-chain esters isolated, and this fraction separated into multimethyl-branched and other esters by normal phase high performance liquid chromatography. Negative ion chemical ionisation gas chromatography mass spectrometry was used to detect diagnostic C29, C30 and C32 mycocerosic acids. Mycocerosic acids were detected in archaeological material for the first time, illustrating that they are valuable biomarkers for the diagnosis of ancient tuberculosis. A 72% correlation with the Coimbra burial record supported TB as the major cause of death. In addition, 30% of the skeletons, positive for mycocerosates, showed the presence of related long-chain mycolipenic acids.
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Affiliation(s)
- Janet E Redman
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Thurman PF, Chai W, Rosankiewicz JR, Rogers HJ, Lawson AM, Draper P. Possible intermediates in the biosynthesis of mycoside B by Mycobacterium microti. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 212:705-11. [PMID: 8462544 DOI: 10.1111/j.1432-1033.1993.tb17708.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Two lipids were isolated from Mycobacterium microti which became labelled when the cells were grown in the presence of [2-14C]propionate. They were purified by thin-layer chromatography and studied by chemical degradation and mass spectrometry. The lipids were identified as phenolphthiocerol dimycocerosate and phenolphthiodiolone dimycocerosate, the aglycosyl derivatives of mycoside B, the phenolic glycolipid produced by M. microti. Cell-free extracts of the organism were able to glycosylate the lipids to form mycoside B in vitro. It is probable that the lipids are intermediates in the biosynthesis of phenolic glycolipids by mycobacteria.
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Affiliation(s)
- P F Thurman
- National Institute for Medical Research, Mill Hill, London, England
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Dobson G, Minnikin DE, Besra GS, Mallet AI, Magnusson M. Characterisation of phenolic glycolipids from Mycobacterium marinum. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1042:176-81. [PMID: 2302417 DOI: 10.1016/0005-2760(90)90004-h] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The phenolic glycolipids from two strains of Mycobacterium marinum have been isolated and characterised. The glycolipids from M. marinum MNC 170 were principally glycosides of diacyl C37, C39 and C41 phenolphthiocerols A, but in M. marinum MNC 842, these lipids were accompanied by glycosides of diacyl phenolphthiodiolones A and novel phthiotriols A with the same overall chain-lengths. The main acyl components of the phenolic glycolipids from M. marinum MNC 170 were C26 dimethyl and C27 and C29 trimethyl-branched fatty acids, but in the lipids of M. marinum MNC 842, the C27 trimethyl acid was the only principal component. The sugar composition of all these glycolipids had been previously shown to correspond to 3-O-methylrhamnose.
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Affiliation(s)
- G Dobson
- Department of Chemistry, The University, Newcastle upon Tyne, U.K
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Mallet AI. Analysis of lyso-platelet activating factor by negative ion gas chromatography/mass spectrometry of the nitrobenzal acetal derivatives. BIOMEDICAL & ENVIRONMENTAL MASS SPECTROMETRY 1988; 16:207-10. [PMID: 3242671 DOI: 10.1002/bms.1200160137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This paper describes the methods that have been employed for the quantification of platelet activating factor (PAF) and its principal metabolite, in biological matrices. In plasma PAF is rapidly hydrolysed to lyso-PAF, which is also the major precursor of PAF. Measurement of lyso-PAF has been accomplished by mass spectrometric methods using cyclic acetal derivatives of the alkyl glycerol produced after removal of the polar head group. We describe the preparation of a novel electron capture derivative for this glycerol and its behaviour under electron impact and negative ion mass spectrometry. High sensitivities have been achieved using the procedures described here.
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Affiliation(s)
- A I Mallet
- Institute of Dermatology, University of London, UMDS, St Thomas's Hospital, UK
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Goren MB, Dhariwal KR, Jenkins ID. Concerning hydrolysis of mycolate esters, of phthiocerol dimycocerosates and of related mycobacterial lipids: an anecdotal account. J Chromatogr A 1988; 440:487-98. [PMID: 3042800 DOI: 10.1016/s0021-9673(00)94554-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We review the experimental difficulties that have been encountered in hydrolyzing mycolic acid esters, their beta-O-substituted analogues, permethylated cord factor, phthiocerol dimycocerosates and similar mycobacterial lipids. Hydrolysis of the beta-O-substituted methyl mycolates is invariably sluggish and is accompanied by considerable beta-elimination to generate mycolenoic acids. Historical evidence for this often undesirable side reaction is presented. Improvements in methodology are described in which hydrolysis is promoted and beta-elimination is minimized. The reaction systems developed were found applicable to hydrolysis of the quite inert phthiocerol dimycocerosates. Permethylation of the recovered phthiocerol provides an excellent derivative for mass spectrometric analysis to define its complete structure.
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Affiliation(s)
- M B Goren
- Department of Molecular and Cellular Biology, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206
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Diez Ibañez MA, Chessebeuf-Padieu M, Nordmann P, Padieu P. Gas chromatography-mass spectrometry analysis of tert.-butyldimethylsilyl derivatives of 2-acetylaminofluorene and metabolites in isolated rat hepatocytes. Cell Biol Toxicol 1987; 3:327-40. [PMID: 3507261 DOI: 10.1007/bf00117869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A new technique for the conversion of 2-acetylaminofluorene and several ring-hydroxylated metabolites to mono- and di-tert.-butyldimethylsilyl derivatives was developed to permit their analysis by gas chromatography-mass spectrometry in order to quantify the metabolism of 2-acetylaminofluorene incubated in freshly isolated rat hepatocytes. This new gas chromatography-mass spectrometry method allowed the separation, identification and quantitation of seven known metabolites comprising five arylhydroxylated compounds, 2-aminofluorene and N-hydroxy-2-acetylaminofluorene.
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Affiliation(s)
- M A Diez Ibañez
- Laboratoire de Biochimie Médicale, Faculté de Médecine, Dijon, France
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