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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 102 (1980), S. 5323-5328 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Ataxia teleangiectatica ; Immunfunktionsstörung ; Lymphozytensubpopulationen ; Apoptose ; CD45RO ; CD45RA ; Key words Ataxia teleangiectasia ; Immunodeficiency ; Lymphocyte subset ; Apoptosis ; CD45RO ; CD45RA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Background: Can a characterisation of the lymphocyte subset in patients with ataxia teleangiectasia offer an explanation for the cellular defect of their immunfunction? Methods: In ten patients with ataxia teleangiectasia and a corresponding control group of individuals of similar age and sex, immunophenotyping was carried out by means of flow cytometric analysis and the use of monoclonal antibodies. Results: Patients with ataxia teleangiectasia showed a reduction of the number of T-cells with a decrease in the T-helper cell subset (CD3: 990/µl, p〈0.0005 and CD4: 568/µl, p〈0.0005). The number of B-cells was low (CD19: 39/µl, p〈0.005). Moreover, there was an increase in highly activated T-lymphocytes which can be seen from a higher percentage of the HLA-DR- and CD45RO-expression in patients with ataxia teleangiectasia compared to the individuals of the control group (HLA-DR: 57%, p〈0.0005 and CD45RO: 82%, p〈0.001). At the same time, the expression of CD95 (Fas/AP01) was clearly increased (CD95: 74%, p〈0.001). Interpretation: The lymphocyte subset of the patients suffering from ataxia teleangiectasia shows a significant decrease of the B- and T-cell subsets. The reduced number of T-helper cells – caused by a CD45RA-cell loss – leads to a change in the relation „RA/RO”. It is possible that there is a link between the imbalance of „RA/RO”, the increase of highly activated T-lymphocytes and the higher expression of CD95 (Fas/APO1).
    Notes: Zusammenfassung Fragestellung: Können durch eine Charakterisierung der Lymphozytensubpopulationen bei Patienten mit Ataxia teleangiectatica Rückschlüsse auf den zellulären Defekt der Immunfunktionsstörung gezogen werden? Methodik: Mit Hilfe der Durchflußzytometrie und des Einsatzes monoklonaler Antikörper führten wir eine Immunophänotypisierung bei jeweils 10 Patienten mit Ataxia teleangiectatica und eines bezüglich des Alters und des Geschlechts gleichverteilten Kontrollkollektivs durch. Ergebnisse: Die Patienten mit Ataxia teleangiectatica zeigten verminderte T-Zell-Zahlen mit Abnahme der T-Helferzell-Subpopulationen (CD3: 990/µl, p〈0,0005 und CD4: 568/µl, p〈0,0005). Auch die B-Zell-Zahl war erniedrigt (CD19: 39/µl, p〈0,005). Die T-Lymphozyten befanden sich darüber hinaus vermehrt im aktivierten Zustand, erkennbar an einer prozentual erhöhten HLA-DR- und CD45RO-Expression (HLA-DR: 57%, p〈0,0005 und CD45RO: 82%, p〈0,001) sowie an einer Verschiebung der Relation „RA/RO” zugunsten der „RO”-Expression. Gleichzeitig war die Expression von CD95 (Fas/APO1) deutlich gesteigert (CD95: 74%, p〈0,001). Schlußfolgerung: Die Veränderungen der Lymphozytensubpopulationen zeigen bei den Patienten mit Ataxia teleangiectatica eine verminderte B- und T-Zell-Zahl. Die CD4-Lymphopenie – verursacht durch einen CD45RA-Zellverlust – bedingt eine Verschiebung der Relation „RA/RO”. Möglicherweise besteht ein Zusammenhang zwischen der Störung der Homöostase „RA/RO” und dem erhöhten Aktivierungsgrad der Zellen sowie der vermehrten CD95(Fas/APO1)-Expression.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3758-3774 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic Energy Release and Hammond Postulate During Intramolecular Aromatic Substitution in 2-Stilbazole IonsIn the mass spectra of 2-stilbazoles 1a-1g and 3- and 4-stilbazoles (2 resp. 3), C13H10Nℸ+ ions, m/z = 180, are formed with high intensities by loss of a H-atom or of a substituent. This is the only fragmentation reaction available to metastable molecular ions of 1a-1g, 2, and 3. Comparison of MI and CA spectra of the C13H10Nℸ+ ions shows, that 4a-azoniaphenanthrene ions a arise from the 2-stilbazoles 1a-1g by an intramolecular substitution reaction of the molecular ions. The dependence of the energy requirements of this reaction has been studied by measurements of ionization and appearance energies and of the release of kinetic energy during the reaction. From this it follows that the reaction occurs via an intermediate Z with a tetracoordinated C-atom at the ortho-position of the phenyl group; the formation of Z determines the activation energy of the total reaction. Z is formed as a chemically activated species and contains excess energy with respect to fragmentation into the reaction products. The partitioning of the excess energy between internal and translational energy of the reaction products depends on the leaving group. This dependence is described with the aid of a quantitative Hammond postulate by the position of the transition state at the reaction coordinate.
    Notes: In den Massenspektren der 2-Stilbazole 1a-1g, sowie des 3- und 4-Stilbazols (2 bzw. 3) werden durch Abspaltung eines H-Atoms oder des Substituenten mit hoher Intensität C13H10Nℸ+-Ionen, m/z = 180, gebildet. Für metastabile Molekül-Ionen von 1a-1g, 2 und 3 ist dies die einzige Zerfallsreaktion. Durch einen Vergleich der MI- und CA-Spektren der C13H10Nℸ+-Ionen ergibt sich, daß bei den 2-Stilbazolen 1a-1g 4a-Azoniaphenanthren-Ionen a durch eine intramolekulare Substitution in den Molekül-Ionen entstehen. Die Abhängigkeit des Energiebedarfs und der Energie-Umsetzung bei dieser Reaktion von der Abgangsgruppe wird durch Messungen der Ionisations- und Auftrittsenergien sowie der bei der Reaktion freigesetzten kinetischen Energie untersucht. Danach verläuft die Reaktion über eine Zwischenstufe Z mit tetrakoordiniertem C-Atom in der ortho-Position des Phenylringes, deren Bildung die Aktivierungsenergie der Gesamt-reaktion bestimmt. Z entsteht als chemisch aktivierte Spezies und besitzt gegenüber einem Zerfall zu den Endprodukten überschüssige Energie. Die Aufteilung der überschüssigen Energie auf innere Energie und Translationsenergie der Reaktionsprodukte wird von der Abgangsgruppe bestimmt. Diese Abhängigkeit wird mit Hilfe eines quantitativen Hammond-Postulats durch die Position des Übergangszustandes auf der Reaktionskoordinate beschrieben.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A non invasive method for measurement of bile acid kinetics in serum using (24-13C)chenodeoxycholic acid has been developed. After oral administration of 50 mg (24-13C)chenodeoxycholic acid, the exponential decay of the 13C atom percent excess was measured in serum using capillary gas chromatography mass spectrometry. This required that isotope ratios were measured with high accuracy and coefficients of variation less than 1% by means of selected ion monitoring and scan averaging. The clinical applicability was tested by repeated determination of pool size, fractional turnover and synthesis rate of chenodeoxycholic acid in one healthy volunteer. This method permitted the determination of pool size, synthesis and conversion of chenodeoxycholic acid into lithocholic acid in man without the use of radioactive tracers and without repeated duodenal intubation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 567-570 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of several benzoyl hetarenes, of 2-benzoyl pyridines substituted at the phenyl and pyridyl group, respectively, and of phenyl substituted 2-benzoyl pyrroles, have been studied with respect to the formation of benzoyl and hetaroyl ions. A correlation between the intensity of benzoyl ions, relative to molecular ion intensity, and the π-electron density at the substituted carbon atom of the hetarene has been observed for benzoyl hetarenes. The relative intensities of (substituted) benzoyl ions of substituted 2-benzoyl pyridines and 2-benzoyl pyrroles are not easily related to substituent constants of Hammett equations. The relative ionization energies of phenyl substituted 2-benzoyl pyridines, however, and the relative appearance energies of substituted benzoyl ions derived therefrom follow the σIP+-constant of Bentley and Johnstone and the σ+-constants of Brown, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1980), S. 122-130 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The loss of substituents X from molecular ions of ortho substituted 2-benzoyl pyridines has been investigated as a function of the dissociation energy of the C—X bond. Comparison of unimolecular and collisional induced decompositions of the resulting [M — X]+ ions and reference ions arising from 3-hydroxypyrido[1,2-α]indole shows that cyclic fragment ions are formed in every case by an intramolecular substitution reaction with the exception of the parent compound (X = H), which gives rise to a mixture of [M — H]+ ions with different structures. The heat of formation of the cyclic ion has been estimated experimentally and by calculation using thermochemical data, and from this value and the appearance energies, the activation energies of the reverse reactions have been evaluated for the different reaction systems. Measurement of the kinetic energy release during the substitution reactions shows that only part of the reverse activation energy is released as kinetic energy. The energy partitioning quotient varies from 0.37 to 0.08 depending on the dissociation energy of the C—X bond or the reaction enthalpy. A sudden change in the energy partitioning quotient is observed with increasing exothermicity of the reaction, paralleling the behaviour of similar reaction systems. These results are interpreted as a demonstration of the influence of the variation of transition state position on the energy partitioning quotient.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron impact fragmentation of methyl ester/methyloxime/trimethylsilyl ether derivatives of prostaglandin E2 and 6-oxo-prostaglandin F1α and the methyl ester/trimethylsilyl ether derivative of prostaglandin F2α is followed by argon collision-activated dissociation in a triple quadrupole mass spectrometer. Daughter ion chromatograms of prostaglandin derivatives show an enormous increase of selectivity compared to the multiple ion detection chromatograms of the same samples in single quadrupole mode.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple method using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) is described for the characterization of acylcarnitines in standard solutions and urinary samples from controls and patients with β-oxidation deficiency disorders. This mass spectrometric approach is compared with other techniques currently utilized for studying acylcarnitines: fast atom bombardment mass spectrometry (FABMS), gas chromatography/chemical ionization mass spectrometry (GC/CIMS) and electrospray ionization mass spectrometry (ESI-MS). MALDI-MS was found to compare favourably with the recently described ESI-MS analysis of acylcarnitines. Both ESI-MS and MALDI-MS share the following advantages: (i) non-requirement of a derivatization step; (ii) easy detection of acylcarnitine esters in standard preparations and urinary samples from human subjects; (iii) detection of fatty acid oxidation disorders from the urinary acylcarnitine profiles in patients suffering from medium-chain acyl-CoA dehydrogenase deficiency (MCADD), multiple acyl-CoA dehydrogenase deficiency (MADD) and mitochondrial carnitine palmitoyltransferase type II (CPT II) deficiency; (iv) sensitivity comparable to FABMS and GC/CIMS, the two reference methods most widely utilized for routine detection of acylcarnitines; and (v) ability (like FABMS but in contrast with GC/CIMS) to detect long-chain acylcarnitines, suggesting that these esters might have been previously underestimated in body fluids from patients with β-oxidation deficiency disorders. MALDI-MS, like ESI-MS, provides a fast and sensitive method for determining carnitine and its esters, with the potential for routine application in neonatal screening for inherited metabolic disorders involving acylcarnitine metabolism.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 68-73 
    ISSN: 0935-6304
    Keywords: MS-MS ; Gas chromatography ; Capillary GC-ECD, GC-MS, GC-MS-MS ; Bleaching ; Chlorine compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatography (GC) with electron capture detection (ECD), GC combined with mass spectrometry (MS), GC with multi-stage mass spectometry (MS-MS), and direct inlet MS-MS have been used to determine 1,1-dichlorodimethyl sulfone (DDS) in aquatic organisms in the receiving waters outside a pulp mill bleach plant. Both GC-MS-MC and direct inlet MS-MS of tissue extracts of fish and mussel appear to be sensitive, selective, and rapid analytical techniques for the determination of DDS.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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