In this analysis, subjects who report coexisting asthma and COPD have a higher risk of obstruction on spirometry and a higher risk of death during follow-up.

Rationale: Hyperventilation of hot humid air induces transient bronchoconstriction in patients with asthma; the underlying mechanism is not known. Recent studies showed that an increase in temperature activates vagal bronchopulmonary C-fiber sensory nerves, which upon activation can elicit reflex bronchoconstriction. Objectives: This study was designed to test the hypothesis that the bronchoconstriction induced by increasing airway temperature in patients with asthma is mediated through cholinergic reflex resulting from activation of these airway sensory nerves. Methods: Specific airway resistance (SR aw ) and pulmonary function were measured to determine the airway responses to isocapnic hyperventilation of humidified air at hot (49 8 C; HA) and room temperature (20-22 8 C; RA) for 4 minutes in six patients with mild asthma and six healthy subjects. A double-blind design was used to compare the effects between pretreatments with ipratropium bromide and placebo aerosols on the airway responses to HA challenge in these patients. Measurements and Main Results: SR aw increased by 112% immediately after hyperventilation of HA and by only 38% after RA in patients with asthma. Breathing HA, but not RA, triggered coughs in these patients. In contrast, hyperventilation of HA did not cause cough and increased SR aw by only 22% in healthy subjects; there was no difference between their SR aw responses to HA and RA challenges. More importantly, pretreatment with ipratropium completely prevented the HA-induced bronchoconstriction in patients with asthma. Conclusions: Bronchoconstriction induced by increasing airway temperature in patients with asthma is mediated through the cholinergic reflex pathway. The concomitant increase in cough response further indicates an involvement of airway sensory nerves, presumably the thermosensitive C-fiber afferents.Keywords: asthma; cough; bronchoconstriction; TRPV1; ipratropium It is extensively documented that breathing cold dry air induces bronchoconstriction in patients with asthma, which results primarily from injury of airway mucosa and release of various bronchoactive autacoids, such as leukotrienes and histamine (1). In contrast, the effects of an increase in temperature on the airway functions in patients with asthma is generally overlooked despite the fact that hyperthermia occurs frequently under normal and pathophysiological conditions. The most common causes of hyperthermia are elevated metabolic rate (e.g., during exercise) and hindered heat dissipation (e.g., in a warm environment). Hyperthermia can also occur under disease conditions, such as in patients suffering from severe fever. Furthermore, tissue inflammation is known to lead to local hyperemia and an increase in tissue temperature in the inflamed area (2, 3). A recent study has reported that the average end-expiratory temperature plateau (as an indirect measurement of the lung tissue temperature) is 2.7 8 C higher in children with asthma than that in healthy control subjects (4).An earlier study by Aitken and Marini ...

This paper introduces a class of rank-order-based template matching criteria that are multiplier-free and independent of the dc variations of the image. The core component of these criteria is a grayscale morphological hit-or-miss transform (GHMT). Experimental results show that the GHMT features sharp and robust indications in the presence of Gaussian noise. The idea of the GHMT is used to develop more general forms of matching criteria that are robust to both Gaussian and impulsive noises.

Transient receptor potential ankyrin type 1 (TRPA1) and vanilloid type 1 (TRPV1) receptors are coexpressed in vagal pulmonary C-fiber sensory nerves. Because both these receptors are sensitive to a number of endogenous inflammatory mediators, it is conceivable that they can be activated simultaneously during airway inflammation. This study aimed to determine whether there is an interaction between these two polymodal transducers upon simultaneous activation, and how it modulates the activity of vagal pulmonary C-fiber sensory nerves. In anesthetized, spontaneously breathing rats, the reflex-mediated apneic response to intravenous injection of a combined dose of allyl isothiocyanate (AITC, a TRPA1 activator) and capsaicin (Cap, a TRPV1 activator) was ∼202% greater than the mathematical sum of the responses to AITC and Cap when they were administered individually. Similar results were also observed in anesthetized mice. In addition, the synergistic effect was clearly demonstrated when the afferent activity of single vagal pulmonary C-fiber afferents were recorded in anesthetized, artificially ventilated rats; C-fiber responses to AITC, Cap and AITC + Cap (in combination) were 0.6 ± 0.1, 0.8 ± 0.1, and 4.8 ± 0.6 impulses/s (n = 24), respectively. This synergism was absent when either AITC or Cap was replaced by other chemical activators of pulmonary C-fiber afferents. The pronounced potentiating effect was further demonstrated in isolated vagal pulmonary sensory neurons using the Ca(2+) imaging technique. In summary, this study showed a distinct positive interaction between TRPA1 and TRPV1 when they were activated simultaneously in pulmonary C-fiber sensory nerves.