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  • Analytical Chemistry and Spectroscopy  (27)
  • Insulin-dependent diabetes  (1)
  • Stabilities and reactivities  (1)
Materialart
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  • 1
    ISSN: 1432-0428
    Schlagwort(e): Insulin-dependent diabetes ; cellular immunity ; mouse ; streptozotocin ; auto-immunity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Anti-B cell auto-immunity may play a role in the pathogenesis of diabetes in mice resulting from multiple subdiabetogenic doses of the pancreatic B cell toxin, streptozotocin. In the present study we have investigated the cytotoxic anti-B cell response in these mice. A major role for B lymphocytes, macrophages, or their products in the cytotoxic response originally detected in vitro was eliminated by passing splenocytes from the mice treated with multiple subdiabetogenic doses of streptozotocin over a nylon wool column. The removal of the adherent cells enhanced the cytotoxicity against a rat insulinoma cell line in vitro by that expected due to enrichment of T-lymphocytes by approximately twofold. The induction of diabetes after multiple subdiabetogenic doses of streptozotocin is strain dependent. Mice of five strains were immunized with rat insulinoma cells, but only splenocytes from the two strains susceptible to multiple subdiabetogenic doses of streptozotocin demonstrated a significant cytotoxic response against the rat insulinoma cells in vitro. Mice pre-immunized with either the rat insulinoma cells or with syngeneic islets labelled in vitro with the hapten trinitrophenol developed hyperglycaemia more rapidly than control mice after multiple subdiabetogenic doses of streptozotocin. In the latter experiment the control mice immunized with complete Freund's adjuvant alone also became hyperglycaemic after a modified multiple subdiabetogenic dose of streptozotocin that did not cause diabetes in non-immunized mice. In mice pre-treated with either adjuvant or cyclophosphamide and then given a modified multiple subdiabetogenic dose of streptozotocin (35 mg/kg × 5 rather than 40 mg/ kg) the degree of hyperglycaemia was reduced and there was no protective effect of cyclophosphamide. However, the mice pre-treated with adjuvant again developed hyperglycaemia more rapidly and to a much higher level than did the mice given multiple subdiabetogenic doses of streptozotocin only. These additional data further support the hypothesis that B-cell destruction after multiple subdiabetogenic doses of streptozotocin results from triggering of an immune response against these insulin-producing cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 69 (1986), S. 147-159 
    ISSN: 1432-2234
    Schlagwort(e): Doubly-charged cations ; Stabilities and reactivities
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Unique features of doubly-charged stable organic ions are examined and the results correlated with experimental observations. Self-consistent field molecular orbital methods are used to compute structures and stabilities of CnH 2 2+ (n=2–9) ions which are prominent in electron impact ionization of hydrocarbon molecules. A simple curve crossing model is employed to rationalize charge transfer reactions of these ions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 296-304 
    ISSN: 1076-5174
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Cluster ions from the continuous-flow fast atom bombardment of several pure, liquid aromatics were examined. Most of the aromatics cluster as (M)n+; however, aromatic bases such as pyridine and aniline also form (M)nH+ ions. The abundance of both (M)n+ and (M)nH+ cluster ions decreases rapidly as n increases. The semi-empirical molecular orbital PM3 method was used to examine energetics of cluster ion formation, binding energies of several aromatic dimer ions and structures of stable cluster ions observed in the desorption process.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 210-212 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 24 (1989), S. 22-26 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Field ionization mass spectra of nitrogen-containing organic compounds were examined as a function of carbon dendrite emitter heating current. The intensities of singly charged molecular, quasimolecular and dimer ions decreased with increasing emitter heating current; whereas, the opposite trend was observed for singly charged fragment ions. The abundance of doubly charged ions originating from aromatic compounds increased with heating current.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 25 (1990), S. 174-180 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The influence of the collision gas on doubly charged ion mass spectra of a selected number of hydrocarbons has been examined. Relative abundances of various product ions in 2E spectra, resulting from charge exchange collisions of doubly charged hydrocarbon ions, do not vary drastically as the collision gas is varied. However, the absolute intensities of these doubly charged ion mass spectra increase significantly when the collision gas is changed from argon to methane to isobutane. Tbese observations are rationalized in terms of a multichannel diabatic curve crossing model.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 595-606 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cluster ions from fast atom bombardment of liquid alcohols and nitriles were examined using a continuous-flow technique. Protonated molecular MnH+ species are the dominant cluster ions observed in molecules of formula M. The abundances of the MnH+ cluster ions decrease monotonically with increasing n, and within a homologous series the MnH+ abundance diminishes more rapidly for higher molecular mass compounds. Reaction products (ROH)n(H2O)H+ and (ROH)n(ROR)H+ are observed also in the case of alcohols, and the ion abundances decrease with increasing n. Radiation damage yields fragment ions and ionic alkyl reaction products which are captured in solvent clusters. Semi-empirical molecular orbital methods were used to examine the energetics of cluster ion formation and decomposition pathways. Metastable decomposition processes exhibit only evaporative loss of monomers, with the probability of loss increasing sharply with n. The evaporative ensemble model of Klots was used to predict the cluster size-dependent trends of metastable dissociation processes observed for alcohol and nitrile cluster ions.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1980), S. 312-316 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The doubly charged ion mass spectra for 12 aliphatic nitriles (1-9 carbon atoms) have been obtained using an Hitachi RMU-7L double focusing mass spectrometer. These spectra show some characteristic features such as extensive loss of hydrogen and the grouping of ions in the spectra into n-1 groups where n is the number of carbon atoms in the molecule (n〈6). There are no indications of HCN or CN loss in the doubly charged ion spectra of the monosubstituted nitriles. SCF calculations of the energy and structure of doubly charged ions in the propionitrile spectra have been carried out.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1982), S. 627-635 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Doubly charged ion mass spectra of 22 amines (2-10 carbon atoms) were determined using an Hitachi RMU-7L double focusing mass spectrometer. Molecular ions were not observed in the spectra of aliphatic amines. The most intense product ion peaks in the spectra of lower molecular weight amines resulted from hydrogen elimination from the molecular ion; however, as amine molecular weight increased the largest peaks resulted from both hydrogen and heavy atom elimination from the molecular ion. Dominant ions in the doubly charged ion spectra of lower molecular weight aliphatic amines were from reactions of [CnH3N]2+ (n:=2, 3, 4) type ions. The spectra of higher molecular weight aliphatic amines spanned a wide mass range. Appearance energies for some of the more prominent ions were measured in the range from 25 to 49 eV. A geometry optimized quantum mechanical self-consistent field molecular orbital treatment was used to compute the energies and structural parameters of prominent ions in the doubly charged ion mass spectra.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1987), S. 64-69 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cross sections for charge transfer reactions of organic ions containing oxygen have been obtained using time-of-flight techniques. Charge transfer cross sections have been determined for reactions of 2.0 to 3.4 keV ions produced by electron impact ionization of oxygen containing molecules such as methanol, ethanal and ethanol. Experimental cross section magnitudes have been correlated with reaction energy defects computed from ion recombination energies and target ionization energies. Large cross sections are observed for reacting systems with small energy defects.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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