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  • 13C CP-MAS  (1)
  • Key words: Sensory irritation – Pulmonary irritation – Airflow limitation – Mice – Airborne chemicals – Propranolol – Carbamylcholine – 2-Chlorobenzylchloride – Trigeminal nerve endings – Vagal nerve endings  (1)
  • Respiratory tract  (1)
Materialart
Erscheinungszeitraum
Schlagwörter
  • 1
    ISSN: 1432-0738
    Schlagwort(e): Breathing pattern ; Mice ; Airborne chemicals ; Respiratory tract
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A system was developed for exposure of unanesthetized mice to airborne chemicals and for continuous measurement of their breathing pattern prior to, during and following exposure. By measuring inspiratory and expiratory airflows (VI and VE), and integration with time to yield tidal volume (VT), we obtained characteristic modifications to the normal breathing pattern. These permitted recognition that a specific portion of the respiratory tract was affected by the selected airborne chemicals. Following recognition, we also quantitated the degree of effect using one specific measurement in each case. An effect on the upper respiratory tract, induced by the sensory irritant, 2-chlorobenzylchloride, was quantitated by measuring a decrease in respiratory frequency. An effect on the conducting airways, induced by the airway constrictor, carbamylcholine, was quantitated by a decrease in VE at the mid-point of VT. An effect at the alveolar level, induced either by the vagal nerve ending stimulant, propranolol, or by the pulmonary irritant, machining fluid G, was quantitated by an increase in the length of a pause induced at the end of expiration. The system is easy to construct and operate and can be used to rapidly evaluate the effects of airborne chemicals on the respiratory tract.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0738
    Schlagwort(e): Key words: Sensory irritation – Pulmonary irritation – Airflow limitation – Mice – Airborne chemicals – Propranolol – Carbamylcholine – 2-Chlorobenzylchloride – Trigeminal nerve endings – Vagal nerve endings
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The pattern and timing of a normal breath in unanesthetized mice was analyzed from measurement of inspiratory and expiratory airflows (V.I and V.E). Airflow was measured via a differential pressure transducer, attached to a pneumotachograph, which itself was attached to a body plethysmograph into which a mouse was placed. The analog voltage from the differential pressure transducer was digitized and stored for analysis on a microcomputer. Criteria were developed to classify each breath as normal (N) or belonging into one of seven abnormal categories. The abnormal categories were arrived at by computer analysis, recognizing specific modifications of the normal pattern into patterns of: sensory irritation of the upper respiratory tract (S), airflow limitation within the conducting airways of the lungs (A) or pulmonary irritation at the alveolar level (P). Combinations of these effects, i.e., S+A, P+A, P+S and P+S+A were also recognized. Computer analysis of each breath also permitted quantitative evaluation of the degree of S, A or P abnormalities. To induce each type of effect we used inhalation exposures to 2-chlorobenzylchloride, carbamylcholine or propranolol. We propose that this approach will permit rapid evaluation of the possible effects of airborne chemicals at three levels of the respiratory tract, with the classification of the type of effect easily obtained in an objective way using well defined criteria, followed by quantitation of the degree of each effect.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2503-2512 
    ISSN: 0887-624X
    Schlagwort(e): PAN ; FT-IR ; 13C CP-MAS ; Py-GC-MS ; cyclization ; thermal degradation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: PAN undergoes chemical decomposition in stages on thermal treatment. In the literature, several mechanisms were proposed for the degradation process. However, the decomposition pathway and the structural rearrangement of solid residue in relation to the loss of volatile products are not fully understood. The degradation process has therefore received further attention in this work by employing a combination of FT-IR, high-resolution solid-state 13C-NMR, pyrolysis GC-MS, and microelemental analysis. These investigations have established that PAN decomposes to gaseous and volatile products over a range of temperatures (150-590°C) with concurrent stabilization of the structure of residual matter occurring on a parallel course. While linear polymerization of nitrile group is the principal reaction in the decomposition process, cyclization followed by extended conjugation is the notable exothermic process. No evidence has been obtained for the formation of oxygen-containing chromophores either as intermediates or as part of the chemical structure of the residue. Temperature sensitivity of oligomer formation has been established through pyrolysis-GC-MS studies. The overall decomposition profile of PAN has thus been established. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2503-2512, 1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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