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Abstract
A wind tunnel bioassay and video system were used to observe Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) landing on glass cylinders, heated to human skin temperature (34 degrees C) and treated with aqueous solutions of oxocarboxylic acids. Six of nine compounds tested: 2-oxobutanoic, 2-oxo-3-methylbutanoic, 2-oxopentanoic, 2-oxo-3-methylpentanoic, 2-oxo-4-methylpentanoic and 2-oxohexanoic elicited significant landing responses in comparison to a water control. Landing responses appeared to be restricted to C4-C6, 2-oxocarboxylic acids. A solution of 1 microg/microL of 2-oxopentanoic acid elicited the highest level of response that was temperature dependent: significant numbers of landings occurred only within +/-2 degrees C of human skin temperature. Chemical analysis by linked gas-liquid chromatography/mass spectrometry of methyl-oxime, trimethylsilyl derivatized samples of human sweat extracts revealed the presence of 2-oxopropanoic (pyruvic) acid and three behaviourally active, branched chain acids: 2-oxo-3-methylbutanoic, 2-oxo-3-methylpentanoic and 2-oxo-4-methylpentanoic.
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Affiliation(s)
- T P Healy
- Imperial College at Wye, University of London, Ashford, Kent, UK.
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2
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Baumann C, Cintora MA, Eichler M, Lifante E, Cooke M, Przyborowska A, Halket JM. A library of atmospheric pressure ionization daughter ion mass spectra based on wideband excitation in an ion trap mass spectrometer. Rapid Commun Mass Spectrom 2000; 14:349-356. [PMID: 10700037 DOI: 10.1002/(sici)1097-0231(20000315)14:5<349::aid-rcm873>3.0.co;2-p] [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] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A searchable library of MS/MS spectra obtained using a quadrupole ion trap mass spectrometer and electrospray or atmospheric pressure chemical ionization is presented. The application of wideband excitation (activation) and normalized collision energy leads to highly reproducible mass spectra which are searched using the NIST algorithm. Flow injection and LC/MS/MS applications of this powerful technique in the biomedical (diastereoisomeric steroids, morphine glucuronides, isovalerylcarnitine) and environmental (pirimicarb and desmethyl-pirimicarb) areas are described.
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Affiliation(s)
- C Baumann
- Bioanalytical Services Unit, Centre for Chemical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
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Halket JM, Przyborowska A, Stein SE, Mallard WG, Down S, Chalmers RA. Deconvolution gas chromatography/mass spectrometry of urinary organic acids--potential for pattern recognition and automated identification of metabolic disorders. Rapid Commun Mass Spectrom 1999; 13:279-84. [PMID: 10097403 DOI: 10.1002/(sici)1097-0231(19990228)13:4<279::aid-rcm478>3.0.co;2-i] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The National Institute of Standards and Technology (NIST) Automated Mass Spectral Deconvolution and Identification System (AMDIS) is applied to a selection of data files obtained from the gas chromatography/mass spectrometry (GC/MS) analysis of urinary organic acids. Mass spectra obtained after deconvolution are compared with a special user library containing both the mass spectra and retention indices of ethoxime-trimethylsilyl (EO-TMS) derivatives of a set of organic acids. Efficient identification of components is achieved and the potential of the procedure for automated diagnosis of inborn errors of metabolism and for related research is demonstrated.
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Affiliation(s)
- J M Halket
- Centre for Chemical Sciences, Royal Holloway, University of London, Egham, UK
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Affiliation(s)
- J M Halket
- Bioanalytical Unit, Bernhard Baron Memorial Research Laboratories, London, UK
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Halket JM, Watkins PJ, Przyborowska A, Goodwin BL, Clow A, Glover V, Sandler M. Isatin (indole-2,3-dione) in urine and tissues. Detection and determination by gas chromatography-mass spectrometry. J Chromatogr 1991; 562:279-87. [PMID: 2026698] [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] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A simple procedure based upon capillary column gas chromatography-mass spectrometry (GC-MS) is described for the detection and determination of isatin (indole-2,3-dione) in body fluids and tissues. After addition of 5-methylisatin as internal standard to urine or tissue homogenates, organic extracts are dried and derivatized successively with hydroxylamine hydrochloride and the reagent N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA). The tert.-butyldimethylsilyl derivatives obtained show good GC-MS properties and allow quantification by selected-ion monitoring of m/z 333 (isatin) and m/z 347 (internal standard). Adult and newborn human urine output values lie in the ranges 0.4-3.2 mg/mmol of creatinine (5-30 mg per 24 h) and 0.002-0.518 mg/mmol of creatinine, respectively. There is a discontinuous regional distribution in rat tissues. The GC-MS properties of a number of derivatives formed by successive reaction of isatin with hydroxylamine hydrochloride (or methoxyaminehydrochloride or ethoxyamine hydrochloride) and MTBSTFA, bis(trimethylsiyl)trifluoroacetamide, pentafluoropropionic anhydride or pentafluorobenzyl bromide are also described.
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Affiliation(s)
- J M Halket
- Department of Chemical Pathology, Royal Postgraduate Medical School, Queen Charlotte's and Chelsea Hospital, London, U.K
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6
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Lisboa BP, Willig RP, Halket JM. Improved Separation of C21-Steroids of Wide Polarity Range By Application of Sephadex Lh-20. Successive Solvent Systems and Thin-Layer Reflectance Spectrometry. ACTA ACUST UNITED AC 1991. [DOI: 10.1080/01483919108049613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Clow A, Davidson J, Glover V, Halket JM, Milton AS, Sandler M, Watkins PJ. Isatin and tribulin concentrations are increased in rabbit brain but not liver following pentylenetetrazole administration. Neurosci Lett 1989; 107:327-30. [PMID: 2616043 DOI: 10.1016/0304-3940(89)90840-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Isatin has recently been identified in rat tissues and normal human urine where it constitutes the major part of the endogenous monoamine oxidase inhibitor, tribulin. In this study, we have measured both isatin (by gas chromatography/mass spectrometry) and tribulin (inhibition of a standard rat liver monoamine oxidase preparation) in extracts of rabbit brains and livers after intravenous administration of the anxiogenic, proconvulsant agent pentylenetetrazole. There were increased levels of both isatin and tribulin in rabbit brains, but not in livers, after pentylenetetrazole, compared with saline treated controls. This finding supports the hypothesis that isatin is a component of tribulin activity and may have a role in anxiety or epilepsy.
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Affiliation(s)
- A Clow
- Department of Chemical Pathology, Queen Charlotte's and Chelsea Hospital, London, U.K
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8
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Abstract
Purified tribulin, an endogenous monoamine oxidase (MAO) inhibitor, has been identified by direct probe insertion mass spectrometry as the indole-2,3-dione, isatin. A gas chromatographic-mass spectrometric assay for isatin has been developed and used to measure its relatively high concentrations in unpurified human urine, and in rat heart and brain. Isatin is a known compound with a broad range of biological activity; this is the first report of its presence in the animal body. Isatin is a potent inhibitor of MAO, particularly of MAO B (IC50, 3 microM), and also binds to central benzodiazepine receptors (IC50 against clonazepam, 123 microM).
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Affiliation(s)
- V Glover
- Department of Chemical Pathology, Queen Charlotte's Hospital, London, England
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9
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Abstract
The analytical application of direct pyrolysis (Py) field ionization (FI)-mass spectrometry (MS) und Curie-point pyrolysis gas chromatography-mass spectrometry (Py-GC/FIMS) to various whole foodstuffs is described for the first time. The former technique yields highly differentiated information from the sample in typically 15 min, namely the molecular weight distribution of released volatiles and pyrolysis products in a single spectrum which, owing to the good reproducibility and high significance of the resulting data, has previously been shown to be suitable for the application of chemometric methods. Such mass spectral peaks are further characterized and assigned by high resolution mass measurement and/or by electron ionization after Curie-point pyrolysis and gas chromatographic separation of the components. In this first report, typical results are presented for ground roasted coffee, rosehip tea, wheatmeal biscuit, chocolate drink powder and milk chocolate. The FI mass spectrum obtained from the latter sample is compared with those obtained using the complementary soft ionization techniques of chemical ionization (CI) and direct chemical ionization (DCI).
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Affiliation(s)
- J M Halket
- Department of Trace Analysis, Fachhochschule Fresenius, Wiesbaden, Federal Republic of Germany
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Abstract
The skin of preterm infants varies considerably in its level of maturity. To understand skin absorption in premature infants better, we report a technique for the assessment of percutaneous absorption at various gestational and postnatal ages using stable, isotope-labeled (13C6) benzoic acid. Our results indicate that in the preterm infant, this method detects enhanced skin absorption in the first postnatal days, which declines over three weeks to that expected of a full-term infant. This approach also indicates an inverse relationship between gestational age and skin absorption, as well as postnatal age and skin absorption. The reported technique is a safe and noninvasive method using a model skin penetrant for the study of percutaneous absorption in preterm infants from which basic data may be derived to add to our understanding of skin barrier function.
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Affiliation(s)
- D P West
- Department of Dermatology, University of Illinois, Chicago 60680
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Halket JM, Schulten HR. Simple pyrolysis chamber modification for capillary column curie-point pyrolysis gas chromatography - mass spectrometry of complex biomaterials. ACTA ACUST UNITED AC 1986. [DOI: 10.1002/jhrc.1240091013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Lisboa BP, Halket JM, Ganschow I, Ruiz-Gonzalez MDC. Steroid excretion in a case of 17 alpha-hydroxylase deficiency investigated by computerized gas chromatography-mass spectrometry. ACTA MEDICA PORT 1980; 1:433-49. [PMID: 7415860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Albers HK, Halket JM, Lisboa BP. [The problem of characterization of sterins in the gingiva by means of gas chromatography--mass spectrometry]. Dtsch Zahnarztl Z 1978; 33:695-700. [PMID: 280451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Methods suitable for demonstrating previously unidentifiable substances in healthy and diseased gingiva via gas chromatography/mass spectrometry were described. The advantage of these methods is that the substances can be directly demonstrated from the tissue available. The steps necessary to isolate and demonstrate the substances were explained on the basis of the phytosterol campesterol.
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