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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 71 (1997), S. 157-164 
    ISSN: 1432-0738
    Keywords: Key words Sulphur mustard  ;  Breathing pattern  ;   Sensory irritation  ;  Airflow limitation  ;  Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A head-only exposure assembly was used for exposing mice to vapours of sulphur mustard (SM). The respiration was monitored using an on-line computer program, capable of recognizing the breathing pattern as sensory irritation, airflow limitation and pulmonary irritation. SM was dissolved in acetone and vapourized using a compressed air nebulizer. Mice were exposed to the vapours (8.5, 16.9, 21.3, 26.8, 42.3 and 84.7 mg/m3) for 1h in a body plethysmograph fitted with a 20-gauge needle and a microphone for sensing the respiratory flow signals. The signals were amplified, digitized and integrated to give tidal volume, and stored in a computer for further analysis. The respiration of the mice was followed for modifications in the breathing pattern until 7 days post-exposure. SM induced sensory irritation during exposure, and there was a concentration dependent decrease in the respiratory frequency and an increase in tidal volume. Lower concentrations showed recovery after stopping the exposure. RD50, the concentration that depresses 50% of the respiration was estimated to be 27.4 mg/m3. Following exposure to higher concentrations the animals started dying after 6␣days. The LC50 was estimated to be 42.5 mg/m3 (14␣days observation period). The respiratory frequency decreased on subsequent days of exposure depending upon the exposure concentration, and the breathing pattern was characteristic of airflow limitation. The ratio of flow/tidal volume was decreased following exposure to concentrations of 26.8 and 42.3 mg/m3. The ratio of flow/tidal volume may be a better measurement than the measurements based on flow alone for the assessment of airflow limitation. Pulmonary irritation was not observed showing that the lungs were not affected. The body weight of the animals decreased progressively. The present methodology will be useful for identifying the effects of SM on the respiratory system, one of the end-points considered when establishing occupational exposure limits.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0738
    Keywords: Breathing pattern ; Mice ; Airborne chemicals ; Respiratory tract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9605
    Keywords: Ag doping ; YBCO thin film ; growth model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The improvement in the properties of laser-ablated Ag-doped YBa2Cu3O7−x (YBCO) thin films in both normal and superconducting states has been interpreted using a growth model. The model is simple and is based on the widely accepted characteristics of Ag such as its flux action at high temperature and nonreactivity with YBCO phase.
    Type of Medium: Electronic Resource
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