Administration of bleomycin into the lungs of experimental animals has been utilized as a model to understand human pulmonary fibrosis. Most of the studies, however, have focused on early stages of the lung reaction. We hypothesized that chronic stages of the model may not mimic idiopathic pulmonary fibrosis, since in preliminary studies, lung volume and compliance were not decreased. Eight male Sprague-Dawley rats receiving intratracheal bleomycin (0.5 U/100 g body weight) underwent measurement of FRC, inspiratory capacity, and lung compliance 120 d later. Lung histologic changes were evaluated using light microscopy. Eight rats without intervention served as controls. Results show that our model, in early stages, has histologic changes no different from those previously described elsewhere. In chronic stages, however, the model does not behave as a restrictive syndrome: FRC is normal or increased, whereas lung compliance is normal. Focal peribronchiolar inflammation and fibrosis associated with paracicatricial emphysematous changes are the main histologic features of long-term lung remodeling after bleomycin. We conclude that while the chronic stages of the model may be informative in understanding mechanisms of fibrosis, care should be taken not to extrapolate to human idiopathic pulmonary fibrosis. We speculate that the model might resemble a particular subgroup of human interstitial lung disease, namely, those involving peribronchiolar structures.

OBJECTIVE: An association between obesity and asthma symptoms has been reported in the literature, but such a relationship is inconsistent if atopic status or bronchial hyper responsiveness (BHR) is considered. The objective was to assess the association between obesity and asthma symptoms or BHR in adults. METHODS: A study was carried out in 1232 people born between 1974 and 1978 in Chile. The participants completed the European Community Health Survey questionnaire, were skin tested and subject to a BHR challenge to methacholine. MEASUREMENTS: Weight, height and waist circumference were measured and body mass index (BMI) was calculated. RESULTS: There was a positive association between wheeze and breathlessness following exercise and BMI (both with an OR 1.03, 95% CI 1.00-1.06), the associations with wheeze tended to disappear in women who did react at least to one allergen, and persisted in those who did not react to any allergens. BMI was negatively associated with BHR (OR 0.93, 95% CI 0.89-0.97). Waist circumference was not associated with asthma symptoms and it was negatively associated with BHR. CONCLUSION: Although there was an association between BMI and asthma symptoms, there were weaknesses in the evidence because waist circumference, a more direct measure of obesity than BMI, was not associated with asthma symptoms, and BMI and waist circumference were negatively associated with BHR.

Air pollution in the form of fine particulates, mostly from vehicular exhaust, may adversely affect infants' respiratory health with potential for chronic effects later in life.

Four sets of experiments on surfactant secretion were performed using New Zealand rabbits under light pentobarbital anesthesia. Pa02, Paco2, and pHa remained normal during all experiments. In controls lung lavage yielded 1.62 +/- 0.26 (SD) mg of alveolar phospholipid (PL)/g lung; disaturated phosphatidylcholine comprised 55.5% of total PL. a) Acetylcholine infusion into the left pulmonary artery for 1-4 h caused a 13% increase in alveolar PL of left as compared to right lung. b) Efferent left vagus stimulation for 1 h increased alveolar PL of right and left lungs 31% as compared to controls (P = 0.012). c) Increasing minute ventilation by 100% by augmenting dead space for periods of 1, 2, and 4 h, increased alveolar PL 45% (P = 0.001), 54%, (P = 0.002), and 25% (P = 0.004), respectively, compared to controls. d) Administration of atropine prevented the increase in alveolar PL caused by increased ventilation. These findings show that increased ventilation can stimulate surfactant release through a cholinergically mediated mechanism but do not rule out the participation of other mechanisms.