Indicator Of Airway Obstruction Research Articles

Early-life cadmium exposure elevates susceptibility to allergic asthma in ovalbumin-sensitized and challenged mice

Increasing evidence have demonstrated that early-life exposure to environmental toxicants elevates risk of allergic asthma. Cadmium (Cd) is widely present in the environment. The purposes of this study were to evaluate the impact of early-life Cd exposure on susceptibility to ovalbumin (OVA)-evoked allergic asthma. Newly weaned mice were subjected to a low concentration of CdCl2 (1 mg/L) by drinking water for 5 consecutive weeks. Penh value, an index of airway obstruction, was increased in OVA-stimulated and challenged pups. Abundant inflammatory cells were observed in the lung of OVA-exposed pups. Goblet cell hyperplasia and mucus secretion were shown in the airway of OVA-stimulated and challenged pups. Early-life Cd exposure exacerbated OVA-evoked airway hyperreactivity, Goblet cell hyperplasia and mucus secretion. The in vitro experiments showed that mucoprotein gene MUC5AC mRNA was upregulated in Cd-exposed bronchial epithelial cells. Mechanistically, endoplasmic reticulum (ER) stress-related molecules GRP78, p-eIF2α, CHOP, p-IRE1α and spliced XBP-1 (sXBP-1) were elevated in Cd-subjected bronchial epithelial cells. The blockade of ER stress, using chemical inhibitor 4-PBA or sXBP-1 siRNA interference, attenuated Cd-induced MUC5AC upregulation in bronchial epithelial cells. These results indicate that early-life Cd exposure aggravates OVA-induced allergic asthma partially through inducing ER stress in bronchial epithelial cells.

Genomic Regions 10q22.2, 17q21.31, and 2p23.1 Can Contribute to a Lower Lung Function in African Descent Populations.

Accumulated evidence supports the contribution of genetic factors in modulating airway function, especially ancestry. We investigated whether genetic polymorphisms can affect lung function in a mixed Brazilian child population using the admixture mapping strategy through RFMix software version 1.5.4 (Stanford University, Stanford, CA, USA), followed by fine mapping, to identify regions whereby local African or European ancestry is associated with lung function measured by the forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) ratio, an indicator of airway obstruction. The research cohort included 958 individuals aged 4 to 11 years enrolled in the SCAALA (Social Change, Asthma, Allergy in Latin America) Program. We identified that African ancestry at 17q21.31, 10q22.2, and 2p23.1 regions was associated with lower lung function measured by FEV1/FVC p < 1.9 × 10−4. In contrast, European ancestry at 17q21.31 showed an opposite effect. Fine mapping pointed out 5 single nucleotide polymorphisms (SNPs) also associated in our replication cohort (rs10999948, rs373831475, rs8068257, rs6744555, and rs1520322). Our results suggest that genomic regions associated with ancestry may contribute to differences in lung function measurements in African American children in Brazil replicated in a cohort of Brazilian adults. The analysis strategy used in this work is especially important for phenotypes, such as lung function, which has considerable disparities in terms of measurements across different populations.

Predicting preoperative pulmonary function in patients with thoracic adolescent idiopathic scoliosis from spinal and thoracic radiographic parameters

PurposeThe objective was to analyse the effect of thoracic morphology on pulmonary function in adolescent idiopathic scoliosis (AIS) to predict preoperative lung function.MethodsA total of 170 consecutive preoperative patients (average age 15.1 years) with Lenke 1 and 2 AIS underwent pulmonary function testing. Thirteen deformity parameters, including rib hump size, rib asymmetry, spinal intrusion and thoracic/lung dimensions in the sagittal and coronal plane, were measured on whole-spine radiographs. Lung function parameters were expressed as z-scores. Correlation and regression analysis of these parameters with lung function were performed.ResultsMean thoracic Cobb (MT) was 69.1°, and mean T5–T12 thoracic kyphosis (TK) was 21.8°. MT correlated significantly with FEV1 and FVC (rs = − 0.40 and − 0.38). TK correlated weakly with FEV1 and FEV1/FVC (rs = 0.23 and 0.25). FEV1 and FVC were best predicted by the inverse apical vertebra body–rib ratio (AVBRr−1, rs = 0.46 and 0.42), rib hump depth index (RHDi, rs = − 0.52 and − 0.50) and spinal intrusion ratio (SIr, rs = − 0.50 and − 0.45). The kyphosis–lordosis index (KLi) correlated with FEV1/FVC (rs = 0.29). Multivariate regression analysis of coronal and sagittal Cobb angles produced a model which explained 35% and 30% of the variance in FEV1 and FVC, whilst a regression model consisting of AVBRr−1 and SIr was able to predict 54% and 48%.ConclusionAVBRr−1, RHDi and SIr measured on posterior–anterior and lateral radiographs provide better estimations of lung function in preoperative AIS patients than Cobb measurements. KLi was an indicator of airway obstruction as measured by FEV1/FVC.

The highs and lows of wheezing: A review of the most popular adventitious lung sound.

Wheezing is the most widely reported adventitious lung sound in the English language. It is recognized by health professionals as well as by lay people, although often with a different meaning. Wheezing is an indicator of airway obstruction and therefore of interest particularly for the assessment of young children and in other situations where objective documentation of lung function is not generally available. This review summarizes our current understanding of mechanisms producing wheeze, its subjective perception and description, its objective measurement, and visualization, and its relevance in clinical practice.

Biochemical Markers of Cardiac Risk and Their Relation to Spirometric Indices of Airway Obstruction Among COPD Patients

Monitoring of the cardiac status of COPD (Chronic Obstructive Pulmonary Disease) and comparing them with their respiratory indices thought to be predictive markers of the general health of these patients and be indicative, even prognostic, of any impending deterioration. This study was destined to evaluate various aspect of serum prognostic factors in COPD patients. This study was conducted over a period of six months. During this time biochemical markers of 43 (34 male and 9 female) patients suffering from COPD were collected and compared them with those of 40 healthy case control subjects. The Methodology and Exclusion Criteria were strictly adhered to, and based on the statistical analysis shown below the final results were arrived at, which have been discussed at length below. The relation between smoking and COPD found to be controversial, but smoking none the less has a detrimental effect on the respiratory indices and thus, cessation of smoking would definitely benefit these patients, although the extent of the benefit is a matter of debate and further study. As for the individual markers, serum CRP and plasma homocysteine are definitely important as prognostic markers, as well as the indicators of the present stage of the disease. Serum Lipoprotein (a) was not found to be very effective indicator in this study. Homocysteine as well as CRP but not lipoprotein (a), as cardiac indices is inversely related to the respiratory indices of a COPD patient. Measurement of these parameter might help in prognostic evaluation in those patients.

Sputum pentraxin 3 as a candidate to assess airway inflammation and remodeling in childhood asthma.

Pentraxin 3 (PTX3) is a soluble pattern recognition receptor and an acute-phase protein. It has gained attention as a new biomarker reflecting tissue inflammation and damage in a variety of diseases. Aim of this study is to investigate the role of PTX3 in childhood asthma.In total, 260 children (140 patients with asthma and 120 controls) were enrolled. PTX3 levels were measured in sputum supernatants using enzyme-linked immunosorbent assay test. We performed spirometry and methacholine challenge tests and measured the total eosinophil count and the serum levels of total IgE and eosinophil cationic protein (ECP) in all subjects.Sputum PTX3 concentration was significantly higher in children with asthma than in control subjects (P < 0.001). Furthermore, sputum PTX3 levels correlated with atopic status and disease severity among patients with asthma. A positive significant correlation was found between sputum PTX3 and the bronchodilator response (r = 0.25, P = 0.013). Sputum PTX3 levels were negatively correlated with forced expiratory volume in 1 second (FEV1) (r = -0.30, P = 0.001), FEV1/forced vital capacity (FVC) (r = -0.27, P = 0.002), and FEF25–75 (r = -0.392, P < 0.001), which are indicators of airway obstruction and inflammation. In addition, the PTX3 concentration in sputum showed negative correlations with post-bronchodilator (BD) FEV1 (r = -0.25, P < 0.001) and post-BD FEV1/FVC (r = -0.25, P < 0.001), which are parameters of persistent airflow limitation reflecting airway remodeling.Sputum PTX3 levels increased in children with asthma, suggesting that PTX3 in sputum could be a candidate molecule to evaluate airway inflammation and remodeling in childhood asthma.

Potential Airway Obstruction 7 years Following Exposure to Chlorine

Background: On January 6, 2005 there was a train derailment which released~54,430 kg of chlorine into the town of Graniteville, SC, USA, population~7,000. Aim: To assess long-term pulmonary health effects of a single high-concentration exposure to chlorine gas. Methods: Since summer 2012 diagnostic pulmonary function tests with single breath carbon monoxide diffusing capacity(DLCO) are being provided to 600 former Graniteville cotton mill workers to assess long-term health consequences of chlorine exposure(N to-date= 83). Demographic information, respiratory symptoms, exposure and smoking history abstracted from occupational records before the chlorine release are being linked to prospective health assessments. Preliminary data for participants whose lung volumes and DLCOs met ATS criteria were included (lung volumes: n=65, 19/46 exposed/unexposed, DLCO: n=72, 20/52 exposed/ unexposed). Mean percent predicted measures for pulmonary function parameters and DLCO adjusted for hemoglobin were compared between exposed and unexposed millworkers using Fisher exact and T-test. Results: We found a significant increase in percent predicted residual volume (RV) and total lung capacity (TLC) in exposed millworkers (p=0.02). The proportion of millworkers with lower predicted FEV1/FVC ratio was significantly higher in exposed than in unexposed (p&lt;.0001). There were 7/19(37%) exposed who have FEV1/FVC ratio less than 70% of predicted as compared to 3/46(6.5%) unexposed and 10/19(53%) exposed who had FEV1/FVC ratio less than 75% of predicted as compared to 9/46(20%) unexposed. Four of 20 exposed (20%) showed a moderate decrease in DLCO as compared to 6 of 52 unexposed (11%). Conclusion: Our preliminary findings suggested that inhalation of high concentration chlorine increased RV and TLC and decreased FEV1/FVC ratio 7 years after exposure, indicators of airway obstruction or destroyed alveolar septa leading to emphysema like changes. Further research is needed to discern the mechanism behind these changes.

Fluctuation analysis of respiratory impedance waveform in asthmatic patients: effect of airway obstruction

Fluctuation analysis has great potential to contribute to pulmonary clinical science and practice. We evaluated the relationship between asthma and the respiratory impedance recurrence period density entropy (RPDEnZrs) and the variability (SDZrs). A non-invasive and simple protocol for assessing respiratory mechanics during spontaneous breathing was used in a group of 74 subjects with various levels of airway obstruction. Airway obstruction resulted in a reduction in the RPDEnZrs that was significantly correlated with both spirometric indices of airway obstruction (R = 0.48, p < 0.0001) and mean respiratory impedance (R = -0.83, p < 0.0001). These results suggest that the impedance pattern becomes less complex in asthmatic patients, which may explain the reduction in respiratory systems' adaptability to daily life activities. Preliminary evaluations indicate that RPDEnZrs may contribute to the asthma diagnosis, presenting accuracies of 82 and 87 % in patients with moderate and severe airway obstruction, respectively. On the other hand, SDZrs increased with obstruction (p < 0.0001) and was inversely correlated with spirometric indices of obstruction (R = -0.42, p = 0.0003) and directly associated with mean impedance (R = 0.88, p < 0.0001). This analysis contributes to elucidate previous studies and identified respiratory changes in patients with moderate and severe obstruction with an adequate accuracy (85 and 87 %, respectively).

Lung Hyperinflation and Its Reversibility in Patients with Airway Obstruction of Varying Severity

ABSTRACTThe natural history of lung hyperinflation in patients with airway obstruction is unknown. In particular, little information exists about the extent of air trapping and its reversibility to bronchodilator therapy in those with mild airway obstruction. We completed a retrospective analysis of data from individuals with airway obstruction who attended our pulmonary function laboratory and had plethysmographic lung volume measurements pre- and post-bronchodilator (salbutamol). COPD was likely the predominant diagnosis but patients with asthma may have been included. We studied 2,265 subjects (61% male), age 65 ± 9 years (mean ± SD) with a post-bronchodilator FEV1/FVC <0.70. We examined relationships between indices of airway obstruction and lung hyperinflation, and measured responses to bronchodilation across subgroups stratified by GOLD criteria. In GOLD stage I, vital capacity (VC) and inspiratory capacity (IC) were in the normal range; pre-bronchodilator residual volume (RV), functional residual capacity (FRC) and specific airway resistance were increased to 135%, 119% and 250% of predicted, respectively. For the group as a whole, RV and FRC increased exponentially as FEV1 decreased, while VC and IC decreased linearly. Regardless of baseline FEV1, the most consistent improvement following bronchodilation was RV reduction, in terms of magnitude and responder rate. In conclusion, increases (above normal) in airway resistance and plethysmographic lung volumes were found in those with only minor airway obstruction. Indices of lung hyperinflation increased exponentially as airway obstruction worsened. Those with the greatest resting lung hyperinflation showed the largest bronchodilator-induced volume deflation effects. Reduced air trapping was the predominant response to acute bronchodilation across severity subgroups.

1315 Lung Function in Hyperoxia Experimental Model of Newborn Rats

Background and aims: Study of lung function in anexperimental model of bronchopulmonary dysplasia(BPD) induced by hyperoxia in newborn rats. Methods: The subjects of this study were twolitters of Sprague-Dawley rats. Group C (Control):exposure to room air. Group H (Hyperoxia): exposureto 60% of Oxygen from birth and during 14 days. The lung function tests were performed on day 15. Respiratory functional evaluation through a systemof total body plethysmography (Buxco Electronics, Troy, NY, USA): non-invasive analysis system, withthe animal conscious and free, housed in a sealedcontainer. Changes of pressure and volume in thecabin due to respiratory movements are monitoredand used to calculate ventilatory parameters usinga computer application. Results: Two litters with 14 offspring each werestudied. Pulmonary function tests showed adecrease in tidal volume (H: 0.098 ml, C: 0.125 ml, p0,000) with offsetting increase in respiratory rate (H:310 rpm; C: 266 rpm; p 0,03) without differences inminute volume (H: 29.92 ml / min, C: 32.75 ml / min;p 0,186). The index of airway obstruction (Penh) isaltered in the litter exposed to oxygen (p 0, 026). Conclusions:

Lung function measurement in the assessment of childhood asthma: recent important developments

To present three clinically important developments related to the utilization of pulmonary function to objectively assess the asthmatic child. The new asthma guidelines (2007) have added the forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio to the FEV1 as spirometric criteria for classifying asthma. Although a better indicator of airway obstruction, it has not clearly been shown to correlate with clinical criteria. The normal cut point for the ratio used in the guidelines of 85% for children may be too high, and compared to the lower limits of normal of 80%, could result in unnecessary treatment in some children. The bronchodilator response (BDR) phenotype reflects airway lability and has been associated with biomarkers of inflammation and responsiveness to inhaled corticosteroids as well as predicting long-term outcomes. Several studies have shown improved spirometric techniques in preschoolers as well as defining normal values in this age group. Impulse oscillometry (IOS), which is less demanding than spirometry, has been shown to identify asthmatic preschoolers in some cases better than spirometry and possibly identifying obstruction in the peripheral airways. It may also be a more useful test than spirometry in evaluating long-term drug studies. In addition to the FEV1/FVC ratio to detect airway obstruction, the BDR phenotype would appear to give important additional information regarding airway lability and inflammation, and should be included as routine spirometry. IOS is a promising test to identify asthmatic preschoolers, but more studies are needed to determine exactly what it measures and what constitutes normal values.

Effect of ventriculectomy versus ventriculocordectomy on upper airway noise in draught horses with recurrent laryngeal neuropathy

Little is known about the efficacy of bilateral ventriculectomy (VE) or bilateral ventriculocordectomy (VCE) in draught horses. To compare the effect of VE and VCE on upper airway noise in draught horses with recurrent laryngeal neuropathy (RLN) by use of quantitative sound analysis techniques. In competitive draught horses with grade 4 RLN, VE and VCE reduce upper airway noise during exercise, but VCE is more effective. Thirty competitive hitch or pulling draught horses with grade 4 RLN were evaluated for upper airway sound during exercise. Respiratory rate (RR), inspiratory (Ti) and expiratory time (Te), the ratio between Ti and Te (Ti/Te), inspiratory (Sli) and expiratory sound levels (Sle), the ratio between Sli and Sle (Sli/Sle), and peak sound intensity of the second formant (F2) were calculated. Eleven horses were treated with VE and 19 with VCE. After 90 days of voice and physical rest and 30 days of work, the horses returned for post operative upper airway sound evaluation and resting videoendoscopy. VE significantly reduced Ti/Te, Sli, Sli/Sle and the sound intensity of F2. Respiratory rate, Ti, Te and Sle were unaffected by VE. VCE significantly reduced Ti/Te, Ti, Te, Sli, Sli/Sle and the sound intensity of F2, while RR and Sle were unaffected. The reduction in sound intensity of F2 following VCE was significantly greater than following VE. After VE and VCE, 7/11 (64%) and 15/18 (83%) owners, respectively, concluded that the surgery improved upper airway sound in their horses sufficiently for successful competition. VE and VCE significantly reduce upper airway noise and indices of airway obstruction in draught horses with RLN, but VCE is more effective than VE. The procedures have few post operative complications. VCE is recommended as the preferred treatment for RLN in draught horses. Further studies are required to evaluate the longevity of the procedure's results.

Low-dose Volumetric Computed Tomography for Quantification of Emphysema in Asymptomatic Smokers Participating in an Early Lung Cancer Detection Trial

High-resolution computed tomography (CT) is a validated method to quantify the extent of pulmonary emphysema. In this study, we assessed the reliability of low-dose volumetric CT (LDCT) for the quantification of emphysema and its correlation with spirometric indices of airway obstruction. The study population consisted of 102 consecutive current and former smokers participating in a lung cancer screening trial. All subjects underwent spirometry testing and LDCT at entry and a LDCT after 12 months. The extent of emphysema was estimated by 2 techniques; by using the lung attenuation threshold analysis and by visual assessment of the 2 independent radiologists. The reproducibility of these determinations was assessed using test-retest reliability and kappa coefficient of agreement. The correlation of LDCT-based emphysema determinations with indices of airway obstruction on spirometry was also calculated. Eighty percent of the participants were male, with a mean (standard deviation) age of 54.5 (7.5) years, and median pack-years (interquartile range) of 20 (24). Test-retest reliability of all LDCT-based emphysema determinations was very good (intraclass correlation coefficient of 0.92 for the volume of emphysema, and 0.93 for the emphysema index or emphysema volume/total lung volume). Similarly, there was an excellent interrater agreement for visual assessment of emphysema (kappa coefficient=0.91). Higher volumes of emphysema measured quantitatively or visually significantly correlated with spirometric markers of airway obstruction. Volumetric LDCT is a reliable and valid technique for the quantification of emphysema in asymptomatic smokers.

DNA binding activity of transcription factors in bronchial cells of horses with recurrent airway obstruction

Horses with recurrent airway obstruction (RAO) present many similarities with human asthmatics including airway inflammation, hyperresponsiveness, reversible obstruction, and increased NF-κB expression. Studies in experimental asthma models have shown that transcriptions factors such as activator protein-1 (AP-1), GATA-3, cyclic AMP response element binding protein (CREB) and CAAT/enhancer binding protein (C/EBP) may also play an important role in airway inflammation. The purpose of this study was to measure DNA binding activity of these transcription factors in the airways of horses with RAO and to compare it to pulmonary function and bronchoalveolar lavage fluid (BALF) cytology. Seven horses with RAO and six control animals were studied during a moldy hay challenge and after 2 months at pasture. Pulmonary function, BALF cytology and transcription factors’ activities in bronchial brushings were measured during hay and pasture exposures. During moldy hay challenge, RAO-affected horses developed severe airway obstruction and inflammation and a significantly higher airway AP-1 binding activity than in controls. After 2 months on pasture, pulmonary function and airway AP-1 binding activity were not different between RAO and control horses. The DNA binding activity of CREB in airways of RAO-affected horses increased significantly after 2 months at pasture and became higher than in controls. A significant positive correlation was detected between AP-1 binding activity and indicators of airway obstruction and inflammation. Airway GATA-3, CEBP and CREB binding activities were negatively correlated with indices of airway obstruction. However, contrarily to CREB binding activity, GATA-3 and CEBP binding activities were not different between RAO and control horses and were unaffected by changes in environment. These data support the view that AP-1 and CREB play a role in modulating airway inflammation in horses with RAO.

Impact of cethromycin (ABT-773) therapy on microbiological, histologic, immunologic, and respiratory indices in a murine model of Mycoplasma pneumoniae lower respiratory infection.

Mycoplasma pneumoniae is a major etiologic agent of acute lower respiratory infections. We evaluated the antimicrobial and immunologic effects of cethromycin (ABT-773), a ketolide antibiotic, for the treatment of M. pneumoniae pneumonia in a mouse model. Eight-week-old BALB/c mice were inoculated intranasally once with 10(6) CFU of M. pneumoniae on day 0. Treatment was started 24 h after inoculation. Groups of mice were treated subcutaneously with cethromycin at 25 mg/kg of body weight or with placebo daily until sacrifice. Five to ten mice per group were evaluated at days 1, 4, 7, and 10 after inoculation. Outcome variables included bronchoalveolar lavage (BAL) for M. pneumoniae quantitative culture and cytokine and chemokine concentration determinations by enzyme-linked immunosorbent assay (tumor necrosis factor alpha [TNF-alpha], gamma interferon [IFN-gamma], interleukin-1beta [IL-1beta], IL-2, IL-4, IL-12, granulocyte-macrophage colony-stimulating factor, IL-8, monocyte chemoattractant protein 1 [MCP-1], and macrophage inflammatory protein 1alpha [MIP-1alpha]), histopathologic score of the lungs (HPS), and pulmonary function tests (PFT) using whole-body, unrestrained plethysmography at the baseline and post-methacholine exposure as indicators of airway obstruction (AO) and airway hyperresponsiveness (AHR), respectively. The cethromycin-treated mice had a greater reduction in M. pneumoniae culture titers than placebo-treated mice, reaching statistical significance on days 7 and 10 (P < 0.05). HPS was significantly reduced in cethromycin-treated mice compared with placebo-treated mice on days 4, 7, and 10 (P < 0.05). Cytokine concentrations in BAL samples were reduced in mice that received cethromycin, and the differences were statistically significant for 7 of the 10 cytokines measured (TNF-alpha, IFN-gamma, IL-1beta, IL-8, IL-12, MCP-1, and MIP-1alpha) on day 4 (P < 0.05). PFT values were improved in the cethromycin-treated mice, with AO and AHR significantly reduced on day 4 (P < 0.05). In this mouse model, treatment with cethromycin significantly reduced M. pneumoniae culture titers in BAL samples, cytokine and chemokine concentrations in BAL samples, histologic inflammation in the lungs, and disease severity as defined by AO and AHR.

Dietary factors in the pathogenesis of asthma and chronic obstructive pulmonary disease.

This review focuses on the role of dietary factors in the pathogenesis of asthma and chronic obstructive pulmonary disease. Reduced pulmonary function and indicators of airway obstruction have been shown to be strong indicators of mortality; therefore, a link with diet in the pathogenesis of these diseases would have important public health implications. The results of the studies identified in the review suggest that people who have a diet rich in fruit and vegetables have a lower risk of poor respiratory health, and that this may be due to the antioxidant nutrients these foods contain. On the basis of the evidence, it seems justified to promote a healthy diet, high in fruits, vegetables, and whole grain foods and low in alcohol and fatty foods, as set out in existing guidelines for prevention of cardiovascular disease and cancer, to protect respiratory health in both children and adults.

Neuronal Nitric Oxide Synthase Is Associated with Airway Obstruction in BALB/c Mice Exposed to Ozone

Background: The functional role of nitric oxide (NO) and the various nitric oxide synthase (NOS) isoforms in asthma is controversial. Objective: To investigate the role of NO in mice exposed to ozone, three known isoforms of NOS [inducible NOS (iNOS), neuronal NOS (nNOS), and endothelial NOS (eNOS)] were studied. Methods: The expression of iNOS, nNOS, and eNOS was determined in lung by Western blot analysis after exposure to filtered air and ozone (0.12, 0.5, 1 or 2 ppm) for 3 h. Using barometric whole-body plethysmography and increase in enhanced pause (P_enh) as an index of airway obstruction, we measured airway responses to ozone exposure. Bronchoalveolar lavage (BAL) was performed. Nitrate and nitrite were measured using a modified Griess reaction. Results: The nitrate concentration in BAL fluid, which indicates the in vivo generation of NO in airways, from the ozone-exposed group was significantly greater than that from the group exposed to filtered air (631.0 ± 86.4 vs. 152.1 ± 16.9 µmol/l, p < 0.05). The nitrate concentration in BAL fluid was increased more in mice exposed to 2-ppm ozone than that in mice exposed to filtered air or 0.12-, 0.5-, or 1-ppm ozone. Increases in P_enh after exposure to ozone or filtered air were significantly higher in the ozone-exposed groups than in the group exposed to filtered air (p < 0.01). Increases in P_enh were dependent on the ozone concentration. Although the protein levels of eNOS and iNOS determined were within normal levels, the amount of nNOS protein was markedly elevated in airway tissue homogenates of the group exposed to 2-ppm ozone. Conclusion: These findings demonstrate that the nNOS isoform may be involved in airway obstruction in mice exposed to ozone.

The relationship between alveolar epithelial proliferation and airway obstruction after ozone exposure.

Proliferating cell nuclear antigen (PCNA) is a component of multiprotein complexes that are expressed during cell proliferation. Ozone induces cell necrosis and a consequent increase in cell proliferation. To investigate the effects of acute ozone inhalation on cell proliferation and airway obstruction in BALB/C mice, we examined enhanced pause (Penh) as an index of airway obstruction and PCNA expression by immunohistochemical staining. Compared with controls that received filtered air, the ozone-exposed groups had increased PCNA expression in the alveolar epithelial cells. In rank order, the highest PCNA index was found following 2.0 p.p.m. ozone exposure. In the 2.0 p.p.m. ozone group, there was a PCNA index of 16.83 +/- 0.57% (mean +/- SEM; P< 0.01), compared with 4.25 +/- 0.5% at 0.12 p.p.m., 6.83 +/- 0.60 at 0.5 p.p.m and 12.16 +/- 0.48% at 1 p.p.m. Following ozone exposure, Penh was increased in a dose-dependent manner. There was a significant correlation between the PCNA index in alveoli and Penh (r = 0.63, P< 0.01). These data suggest that ozone can induce alveolar epithelial cell proliferation in a dose-dependent manner, and that alveolar epithelial cell proliferation is correlated with airway obstruction.

Noninvasive Method to Measure Airway Obstruction in Nonanesthetized Allergen-Sensitized and Challenged Mice

Background: Conventional methods used to measure bronchoconstriction are invasive, technically demanding and time consuming. Objectives: Our purpose was to evaluate a noninvasive method, by barometric whole-body plethysmography (WBP), to evaluate bronchoconstriction and bronchial hyperreactivity in mice induced by ovalbumin (OA) inhalation challenge in comparison with an invasive method. Enhanced pause (P_enh) was used as an index of airway obstruction. Methods: Eight mice were sensitized by OA (group I) and then challenged with OA. Twenty-four hours later, pulmonary function testing (PFT) was measured by WBP at baseline and after a methacholine (MCh) inhalation challenge. Eight weight-matched normal mice served as controls (group II). Four hours after PFT in a nonanesthetized condition, all animals were anesthetized and paralyzed. Baseline PFT was performed by the maximal forced expiratory maneuver (MFEM), and then the animals were given varying doses of acetylcholine (ACh; 25, 50, 75, 100 µg/kg) injected through the jugular vein. Five seconds after ACh injections, pulmonary functions were examined, including MFEM, peak airway pressure and total lung compliance. After completing PFT, bronchoalveolar lavage (BAL) was performed, the animals were sacrificed, and the lungs were examined histologically. Results: Group I had increased P_enh in response to MCh in the nonanesthetized condition and decreased flow in the anesthetized condition, characterized by greater decreases in MFEM flow rates MFEF 50% and MFEF 25% than the control group. The peak flows, MFEF 75%, MFEF 50% and MFEF 25%, for group I were lower than those for group II at doses of ACh higher than 25 µg/kg. There were concentration-dependent increases in P_enh in response to aerosolized MCh in both groups, but the P_enh in response to aerosolized MCh was significantly enhanced in group I when compared with controls. The doses of MCh required for 100% increases in P_enh were significantly reduced for sensitized and challenged mice. There was a positive correlation between provocative doses PD200 P_enh MCh, PD20 MFEF 50% ACh and PD20 MFEF 25% ACh. There was a negative correlation between the PD200 P_enh MCh and the percentage of eosinophils in BAL fluid. There was an increased total cell count and an increased percentage and absolute number of eosinophils and lymphocytes in the BAL fluid of sensitized animals. OA-sensitized mice also had a severe inflammatory reaction of airway and lung tissue, characterized by congestion, edema and inflammatory cell infiltration and desquamation of bronchial epithelial cells. Conclusion: The noninvasive method of WBP can be used to evaluate airway obstruction and hyperreactivity induced in mice by allergen challenge.

Tidal midexpiratory flow as a measure of airway hyperresponsiveness in allergic mice.

A method for the noninvasive measurement of airway responsiveness was validated in allergic BALB/c mice. With head-out body plethysmography and the decrease in tidal midexpiratory flow (EF(50)) as an indicator of airway obstruction, responses to inhaled methacholine (MCh) and the allergen ovalbumin were measured in conscious mice. Allergen-sensitized and -challenged mice developed airway hyperresponsiveness as measured by EF(50) to aerosolized MCh compared with that in control animals. This response was associated with increased allergen-specific IgE and IgG1 production, increased levels of interleukin-4 and interleukin-5 in bronchoalveolar lavage fluid and eosinophilic lung inflammation. Ovalbumin aerosol challenge elicited no acute bronchoconstriction but resulted in a significant decline in EF(50) baseline values 24 h after challenge in allergic mice. The decline in EF(50) to MCh challenge correlated closely with simultaneous decreases in pulmonary conductance and dynamic compliance. The decrease in EF(50) was partly inhibited by pretreatment with the inhaled beta(2)-agonist salbutamol. We conclude that measurement of EF(50) to inhaled bronchoconstrictors by head-out body plethysmography is a valid measure of airway hyperresponsiveness in mice.