Peripheral noxious stimulation induces CREM expression in dorsal horn: involvement of glutamate

Thermal washout curves have been proposed as noninvasive tools for analysing lower airway dimensions and pulmonary blood flow, but how upper airway heat transfer affects these washout curves is unclear. The present study was designed to compare extrathoracic and tracheobronchial contributions to thermal washout curves. Respiratory frequency, air ambient temperature, and body core temperature (tc) were varied in six male subjects before and after immersion in cold (1.1 degrees C) water for up to 2 h under three conditions: 1) control: ambient temperature (tamb) = 25 degrees C, rectal temperature change (delta tre) = 0 degrees C; 2) pre-immersion: tamb = 4 degrees C, delta tre = 0 degrees C; and 3) post-immersion: tamb = 25 degrees C, delta tre = -0.7 degrees C. Both peak expiratory nasal (tpn) and oral (tpo) airstream temperatures were measured. Each subject was tested twice. Expiratory tpo was generally higher than tpn in all conditions. Increasing breathing rates lowered tpn and tpo in the control and cold air environments. Orifice temperatures, which are presumed to reflect upper airway blood temperatures, correlated with both tpn and tpo. Lowering tc had no effect on washout curves during quiet breathing and affected only tpn during rapid breathing. The results suggest that while tracheobronchial conditions may contribute to thermal washout curves, extrathoracic conditions predominate. Strong correlations between orifice temperatures, peak expiratory nasal temperatures and peak expiratory oral temperature demonstrate the dominant role of upper airway heat exchange in determining thermal washout curves.     

Comparative severity of respiratory lesions of sialodacryoadenitis virus and Sendai virus infections in LEW and F344 rats

In several chronic diseases, lesions are more severe in LEW rats than in F344 rats. To determine whether or not acute viral diseases also are more severe in LEW rats than in F344 rats, we inoculated 6-7-week-old LEW and F344 rats with 10(7.2) cell culture infective units of sialodacryoadenitis virus or 10(4.7) infective units of Sendai virus. Twenty-four rats of each strain were given each virus. Lesions in nasal passages, tracheas, intrapulmonary airways, and pulmonary alveoli in 6 or 12 rats inoculated with each virus were assessed by scoring 5, 10, and 14 days after inoculation. Both viruses caused typical patchy necrotizing rhinitis, tracheitis, bronchitis, and bronchiolitis, with multifocal pneumonitis, in rats of both strains. Mean lesion indices for LEW rats given sialodacryoadenitis virus were significantly different from those for F344 rats for nasal passages on days 10 (0.999 vs. 0.680) and 14 (0.736 vs. 0.278), bronchi on day 5 (0.479 vs. 0.361), and alveoli on day 5 (0.677 vs. 0.275). Lesion indices for LEW rats given Sendai virus were significantly different from those for F344 rats for nasal passages on days 10 (1.000 vs. 0.611) and 14 (0.778 vs. 0.583); trachea on day 10 (0.625 vs. 0.028); bronchi on days 5 (0.476 vs. 0.331), 10 (0.123 vs. 0.013), and 14 (0.038 vs. 0); and alveoli on days 5 (0.413 vs. 0.114) and 10 (0.185 vs. 0.020). Thus, at the tested doses, both viruses caused more severe respiratory tract lesions in LEW rats than in F344 rats.