Staphylococcus aureus and Pseudomonas aeruginosa co-infection is associated with cystic fibrosis-related diabetes and poor clinical outcomes.

Cystic fibrosis-related diabetes (CFRD) patients suffer from accelerated rates of pulmonary decline compared to cystic fibrosis (CF) patients with normal glucose tolerance (NGT). However, the mechanisms underlying this difference are unknown. While CFRD is associated with increased respiratory infections, a link between infection and enhanced pulmonary dysfunction remains unclear. The development of glucose intolerance is spectral, resulting in impaired glucose tolerance (IGT) prior to the diagnosis of CFRD. Inclusion of IGT patients within the NGT group may diminish the ability to identify correlations with CFRD. With this in mind, this study aimed to determine if the association between CFRD and respiratory infections is correlated with pulmonary decline. Respiratory cultures from 234 CF patients with confirmed diagnosis of NGT or CFRD were analyzed to measure rates of infection, focusing on the two most prevalent bacteria in CF, Staphylococcus aureus and Pseudomonas aeruginosa. Infection status was correlated with pulmonary function and confounding clinical variables including age, gender, blood glucose levels, and CF transmembrane conductance regulator (CFTR) phenotype were considered in multivariate analyses. CFRD patients, particularly those with extremely high blood glucose levels, were more likely than NGT patients to be co-infected with S. aureus and P. aeruginosa, compared to infection with only one pathogen. Co-infection was associated with decreased lung function and increased frequency of pulmonary exacerbations, even after adjustment for confounding variables. Alterations in the microbial community composition, as opposed to the presence of a single pathogen, may account for greater pulmonary decline in CFRD patients.

Disposition index identifies defective beta-cell function in cystic fibrosis subjects with normal glucose tolerance.

BACKGROUND: In non-cystic fibrosis (CF) subjects, the disposition index (DI) is a strong predictor of the development of type 2 diabetes. CF subjects are at high risk of diabetes. We hypothesized that DI would be reduced in CF patients with normal glucose tolerance (NGT), indicating ß-cell dysfunction, and DI would worsen with progression from CF with NGT to CF-related diabetes (CFRD). METHODS: This was a cross-sectional study in 39 CF patients and 21 healthy controls (Con) who underwent oral glucose tolerance test (OGTT). Insulin sensitivity was estimated as (1/fasting insulin) and insulin secretion as (∆insulin 0-30min/∆glucose 0-30min). DI was calculated as (insulin sensitivity)×(insulin secretion). RESULTS: Among CF subjects, 14 had NGT, 20 had prediabetes and 5 had CFRD. Among the controls, 14 had NGT and 7 had prediabetes. DI was significantly lower in CF-NGT compared to Con-NGT (p=0.0035). DI was also lower in CFRD compared to CF-NGT (p=0.025). There were no significant relationships in the CF groups between DI and age, BMI, percent body fat or FEV1. CONCLUSION: ß-Cell function as measured by DI is reduced in CF patients compared to non-CF controls-even in CF-NGT-and is decreased further in CF patients with diabetes. If DI proves to be a predictor of the development of CFRD in larger studies, then it could be used to identify CF patients who are at particularly high risk, allowing early interventions aimed to delay or prevent CFRD.

Gene therapy progress and prospects: alpha-1 antitrypsin.

Over the 2 years covered here, there has been one clinical study in which a normal alpha-1 antitrypsin (AAT) gene was delivered to the nasal epithelium of AAT-deficient subjects using plasmid-liposome complexes; a second study using an adeno-associated vector should begin soon. Although progress in clinical studies has been slow, advances in both viral and nonviral vector designs show considerable promise. Strategies that combine liposome technology with imaginative vector design may permit long-term expression of a normal transgene that is sufficient to achieve therapeutic serum AAT concentrations. While reproducing the normal physiology by targeting normal AAT gene expression to the liver is logical, local expression in lung cells may be less demanding of the technology and offers therapeutic benefits that are produced neither by AAT protein therapy nor by AAT gene therapy targeted to the liver. Developing technologies may permit direct correction of the mutant AAT gene using innovative approaches to in vivo gene repair.

Dysregulated cytokine production in human cystic fibrosis bronchial epithelial cells.

Although pulmonary inflammation is an important pathologic event in cystic fibrosis (CF), the relationship between expression of the CF gene and the inflammatory response is unclear. We studied tumor necrosis factor (TNF) alpha and IL-1beta stimulated production of IL-6 and IL-8 by CF, corrected CF, and normal human bronchial epithelial cells in culture. During the first 24 hours of TNFalpha stimulation, CF cells produced significantly more IL-8 than normal or corrected CF cells. In the second 24 hours of TNFalpha stimulation, IL-6 and IL-8 generation ceased in normal and corrected CF cells but accelerated in CF cells, resulting in marked IL-6 and IL-8 accumulation in CF cells. Similar results were found when cells were stimulated with IL-1beta. Finally, when CF cells were grown at 27 degrees C (a culture condition which results in transport of CF transmembrane conductance regulator, CFTR, to the cell membrane and normalization of chloride conductance) TNFalpha-stimulated production of IL-6 and IL-8 reverted to normal. We conclude that dysregulation of cytokine generation by CF bronchial epithelial cells is directly related to expression of mutant CFTR and these observations provide a potential mechanism for persistence of airway inflammation in CF.

RAD in stable lung and heart/lung transplant recipients: safety, tolerability, pharmacokinetics, and impact of cystic fibrosis.

BACKGROUND: RAD is a novel macrolide with potent immunosuppressive and antiproliferative activities. This study characterizes the safety, tolerability, and pharmacokinetics of two different single oral doses of RAD in stable lung and heart/lung transplant recipients with and without cystic fibrosis (CF). METHODS: This was a Phase I, multicenter, randomized, double-blind, two-period, two-sequence, crossover study. Single doses of RAD capsules at doses of 0.035 mg/kg (2.5 mg maximum) or 0.10 mg/kg (7.5 mg maximum) were administered with cyclosporine (Neoral [cyclosporine, USP] modified), steroids, and azathioprine on Day 1. The alternate dose was administered on Day 16. Laboratory assessments, vital signs, and adverse events were recorded throughout the study. RAD pharmacokinetic profiles were assessed over a 7-day period following each dose. Steady-state cyclosporine (CsA) profiles were assessed at baseline and with each RAD dose; RAD and CsA trough concentrations were obtained throughout the study period. RESULTS: Of the 20 patients randomized, 8 had CF and 12 did not. Single doses of RAD were safe and well tolerated. Headache was the most common side effect. RAD produced a mild, dose-dependent, reversible decrease in platelet and leukocyte counts. Cholesterol and triglycerides were minimally affected. At both doses, CF patients had significantly lower peak concentrations of RAD than did non-CF patients (p = 0.03); however, overall exposure (area under the curve/dose) was not different between the groups (p = 0.63). At the higher dose, there was a clinically minor under-proportionality in AUC, averaging -11%. Steady-state pharmacokinetics of CsA were not affected by RAD co-administration.RAD was safe and well tolerated by stable lung and heart/lung transplant recipients with and without CF. The presence of CF did not influence the extent of RAD exposure. Single doses of RAD did not affect the pharmacokinetics of CsA. Ongoing studies are assessing the long-term safety and efficacy of RAD in lung and heart/lung transplantation.

Exaggerated activation of nuclear factor-kappaB and altered IkappaB-beta processing in cystic fibrosis bronchial epithelial cells.

In cystic fibrosis (CF), inflammatory mediator production by airway epithelial cells is a critical determinant of chronic airway inflammation. To determine whether altered signal transduction through the nuclear factor (NF)-kappaB pathway occurs in CF epithelial cells and results in excessive generation of inflammatory cytokines, we evaluated tumor necrosis factor (TNF)-alpha-induced production of the NF-kappaB-dependent cytokine interleukin (IL)-8 and activation of NF-kappaB in three different human bronchial epithelial cell lines: (1) BEAS cells that express wild-type CF transmembrane conductance regulator (CFTR), (2) IB3 cells with mutant CFTR, and (3) C38 cells, which are "corrected" IB3 cells complemented with wild-type CFTR. Treatment of cells with TNF-alpha (30 ng/ml) resulted in markedly elevated NF-kappaB activation and production of IL-8 by IB3 cells compared with BEAS and C38 cells. Despite the differences in NF- kappaB activation, no differences in basal levels of IkappaB-alpha or TNF-alpha- induced IkappaB-alpha processing and degradation were detected among the cell lines. In contrast, the basal level of IkappaB-beta was increased in the IB3 cells. Treatment with TNF-alpha resulted in increased formation of hypophosphorylated IkappaB-beta and increased nuclear localization of IkappaB-beta in IB3 cells compared with the other cell types. These findings provide additional evidence of a dysregulated inflammatory response in CF.

Respiratory-related evoked potentials in children with life-threatening asthma.

Respiratory-related evoked potentials (RREPs) have been elicited by inspiratory occlusion and recorded over the somatosensory cortex. The first positive peak (P(1)) amplitude has been correlated with the magnitude of inspiratory loads. Since children with life-threatening asthma (LTA) have a decreased perceptual sensitivity of inspiratory loads, we hypothesized that a subpopulation of patients with LTA have an impaired ability to sense mechanical loads, and that these patients would have an abnormal RREP. The RREP was recorded from C(Z) -C(3) and C(Z) -C(4) in three groups: LTA asthmatic, control asthmatic, and nonasthmatic children. Two inspiratory-interruption occlusions trials and a control trial were recorded. All the evoked potentials were analyzed after the averaged control trial was subtracted from the averaged occlusion trials. The RREP P(1) peak was observed in all 14 nonasthmatic children and in 14 of 15 control asthmatic children. The RREP was absent in 6 of 11 patients with LTA. When present, there were no between-group significant differences in P(1) peak latency or amplitude. These results demonstrate that the RREP elicited by inspiratory occlusion is present bilaterally in nonasthmatic and asthmatic children. There is a subpopulation of LTA children in which inspiratory occlusion fails to elicit the P(1) peak of the RREP, suggesting an altered neural processing of inspiratory load information.

Transfection of nasal mucosa with a normal alpha1-antitrypsin gene in alpha1-antitrypsin-deficient subjects: comparison with protein therapy.

We sought to determine whether a normal alpha1-antitrypsin (AAT) gene could be expressed in respiratory epithelium and whether local expression would have antiinflammatory effects. In an unblinded study, we delivered a normal AAT gene in a plasmid-cationic liposome complex to one nostril of each of five subjects with AAT deficiency; the other, untreated nostril served as a control. AAT protein concentration in nasal lavage fluid (NALF) increased in the transfected nostril (TN), but not in the control nostril (CN), of every subject, peaking on day 5 at levels about one-third normal (baseline CN, 4.1 +/- 1.2 microg/mg of protein; baseline TN, 4.3 +/- 1.3; day 5 CN, 4.0 +/- 0.5 [p = NS versus baseline]; day 5 TN, 9.0 +/- 1.7 [p < 0.5 versus baseline]); isoelectric focusing identified the transgene-generated protein (M) in the only two patients in whom the measurement was possible. The reverse transcriptase-polymerase chain reaction (RT-PCR), performed on NALF from TN and CN of four of the five subjects, was positive for transgene message in TN in all cases and negative in NALF from CN except for one time point in one subject. Interleukin 8 (IL-8) concentrations in NALF were elevated at baseline (normal [N = 10] = 2.5 +/- 0.5 ng/mg of protein; baseline TN = 5.5 +/- 0.8, p < 0.05 versus normal) and decreased after AAT transfection (TN = 2.9 +/- 0.6, p < 0.05 versus baseline) but not in the control nostril (CN = 6.5 +/- 2.2, p = NS versus baseline). NALF samples taken from four of the patients while receiving intravenous AAT protein showed normal concentrations of AAT, but IL-8 concentrations (10.5 +/- 4.2 ng/mg of protein, p = NS versus baseline) were not decreased from baseline. We conclude that plasmid-cationic liposome delivery of a normal AAT gene to the respiratory epithelium of deficient patients produces potentially therapeutic local AAT concentrations and that AAT gene therapy, unlike AAT protein therapy, is antiinflammatory.

Gene therapy for acute lung injury.

The remarkable transition of biological science into the age of molecular biology held great promise for development of new therapies for treatment of human disease. The fact that the technology exists for analyzing genetic material in exquisite detail and constructing DNA in virtually any desired form was the basis for promising rapid translation into clinical medicine and the final cure for genetically determined diseases; cystic fibrosis is the prime example of such a lung disease. The promise was not kept, at least not in a time frame which was expected. That result is neither because the rationale was faulty nor because the tools of molecular biology were wanting. The devil was and is in the details. How do you deliver DNA to the desired cell targets in amounts sufficient to accomplish the desired effect? Viral vectors have received the most attention, but viral vectors have proven to have both theoretical and practical problems. In the lungs, these vectors have not fulfilled their original promise. Non-viral based strategies work in a general sense, but efficiency of gene delivery in vivo has been a limitation. In addition, the experimental end points in both clinical and preclinical investigation have been most often designed to demonstrate phenomenology rather than potential efficacy. And, why limit the potential of gene therapy to inherited disease? In fact, treatment of acquired diseases by increasing or decreasing expression of a given gene in the lungs that would hasten recovery from an acquired disease might be easier than treating inherited disease because the requirements for duration of transgene expression would be less stringent. Over the past two decades, we have learned enough about the pathogenesis of acute lung injury to predict that increased (or decreased) production of certain biologically active mediators should be beneficial. Genes encoding some of these mediators have been cloned and constructs made which express the genes. It is now possible using either viral or non-viral strategies to deliver expression constructs to the lungs and, since acute lung injury has a dismal prognosis and no effective drugs have been identified, this seems a good clinical target for gene therapy. In preclinical studies, we have shown that increased expression of the gene encoding the constitutive form of the cyclooxygenase gene (COX-1) results in increased production of prostacyclin and PGE2 by the lungs and inhibits endotoxin induced pulmonary hypertension and edema. Additional studies demonstrate that increased expression of the alpha-1 antitrypsin gene in human respiratory epithelium in culture and in vivo has anti-viral and anti-inflammatory effects that are not predicted by extracellular concentrations of the transgene product. Thus, acute lung injury is a reasonable target for gene therapy, and evidence to date indicates that current technology is sufficiently robust to pursue this novel area for treatment of this devastating disease.

Optimization of cationic liposome-mediated gene transfer to human bronchial epithelial cells expressing wild-type or abnormal cystic fibrosis transmembrane conductance regulator (CFTR).

We determined optimum conditions for delivering DNA to transformed human bronchial epithelial cells expressing wild-type (BEAS) or abnormal (2CF) cystic fibrosis transmembrane conductance regulator (CFTR) using cationic liposomes (Lipofectin, [N-(N,N-dimethylaminoethane)carbamyl] cholesterol[DC-Chol]/dioleoylphosphatidylethanolamine[DOPE], or LipofectAMINE) and reporter genes which measured overall transgene expression (luciferase) or the fraction of cells transfected (heat-stable alkaline phosphatase). All liposomes showed dose-related toxicity. Optimal liposome and lipid: DNA ratios were different for BEAS than for 2CF cells. For all 3 liposome preparations, small particle size and net cationic charge related to transfection efficiency. Both LipofectAMINE and DC-Chol/DOPE transfected a maximum of 3% of BEAS cells, but luciferase expression could be increased without increasing the fraction of cells transfected. LipofectAMINE transfected a maximum of 6% of 2CF cells, and luciferase expression could be increased with no further increase in fraction of transfected cells. DC-Chol/DOPE transfected over 12% of 2CF cells with relatively small increases in luciferase expression. We conclude that an optimal cationic liposome and lipid: DNA ratio for transfecting bronchial epithelial cells depends on: (1) small particle size and net cationic charge, (2) whether the cells have the cystic fibrosis defect, and (3) whether the desired outcome is transfection of the maximum fraction of the cells or maximum total expression of the transgene.

Gene therapy in acute critical illness.

The development of techniques for manipulating nucleic acids and strategies for delivering DNA to humans has made gene therapy a reality. Although mostly focused on genetically based diseases so far, there is every reason to expand the concept to include acquired diseases. Critical illness may be a good target for gene therapy because of the high mortality and need for only transient treatment. Genes can be delivered in vivo using viral vectors (replication-deficient adenovirus and adeno-associated virus most often). Viral vectors have some negatives, mainly the triggering of an inflammatory and an immune response. Nonviral DNA delivery systems include liposomes (cationic or anionic), direct DNA injection, and polycation-DNA-glycoconjugates. Combining liposomes with viral components to deliver plasmids with a transgene may improve efficiency of delivery without causing toxicity. In a model of acute lung injury, in vivo delivery of a vector hyperexpressing the prostaglandin synthase gene using cationic liposomes resulted in increased production of prostaglandin E2 and prostacyclin in the lungs, and protected the lungs from the effects of endotoxin. This end-result demonstrates the feasibility of this approach. A similar rationale for the treatment of sepsis could be used. Other promising therapeutic genes would include those encoding antioxidant enzymes or antiproteases. The logistics for moving to initial studies of gene therapy in critically ill humans have been worked out for other diseases; such steps should expedite the exploration of this new category of therapies.

Evaluation of the interrupter technique for the use of assessing airway obstruction in children.

The purpose of this study was to determine if the interrupter technique, a noninvasive method for measuring airflow resistance, could be used to assess airway obstruction in children. In 107 children (74 with asthma, 12 with cystic fibrosis, and 21 without lung disease) conductance (mostly of airways) measured with the interrupter technique (Gint) was correlated with both forced expiratory volume in 1 second (FEV1) and the forced expired flow rate between 25% and 75% of vital capacity (FEF25-75). In addition, 17 children with significant airway obstruction due to asthma also had airway resistance measured by body plethysmography (R(aw)) before and after treatment. Resistance and conductance measurements made with the interrupter technique were subdivided into inspiratory (Rint-insp, Gint-insp) and expiratory (Rint-exp, Gint-exp) values. In the 107 children, a high degree of linear correlation was found between Gint and FEV1; for Gint-exp, r = 0.77 (P < 0.001), and for Gint-insp, r = 0.76 (P < 0.001). There was also good linear correlation between Gint and FEF25-75; for Gint-exp, r = 0.70 (P < 0.001), and for Gint-insp, r = 0.67 (P < 0.001). In the 17 asthmatic children who were tested before and after treatment of their airway obstruction, Rint correlated highly with R(aw); for Rint-exp, r = 0.91 (P < 0.001), and for Rint-insp, r = 0.83 (P < 0.001). The pre- to post-treatment changes in Rint and R(aw) were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Gene therapy for inflammatory diseases.

The concept of gene therapy may be broadened to include transient gene therapy (gene therapeutics) as a potential intervention in prevention and treatment of diseases which are a consequence of triggering the inflammatory response. Functioning genes can be delivered in vivo by a variety of technologies. Liposome technology is particularly attractive for gene therapeutics because plasmid DNA constructs can be delivered using liposomes which express transiently and do not readily incorporate into the host genome. In the lungs, DNA may be targeted by either intravenous or airway delivery. Airway delivery may be achieved either by direct injection into the airways or by aerosolizing liposome-DNA constructs. Expression of transgenes might also be targeted to areas of inflammation by choosing DNA constructs which contain the appropriate regulatory regions. Several genes have been cloned which are directly relevant to manipulating the inflammatory response and this technology could, in theory, by using either sense or antisense constructs, provide an opportunity to increase or decrease proteins relevant to the inflammatory response. Because of rapid progress in the technology of molecular biological techniques, and rapid progression of human trials using gene transfer methodologies, it is likely that extension of gene therapy to acute diseases such as those which are characterized by inflammation will open a new vista for pharmacological approaches to these complex diseases.

Subacute effects of respiratory syncytial virus infection on lung function in lambs.

We examined the effects of ovine respiratory syncytial virus (RSV) infection on lung mechanics, lung histology, and airway reactivity in lambs. Nine lambs were inoculated with ovine RSV and seven control lambs with normal saline or viral media. Serum neutralization titers were obtained prior to and 3 weeks post-inoculation (PI). Open lung biopsies were performed 1 and 3 weeks PI. Lung mechanics including dynamic compliance (Cdyn), resistance of the lung (RL), and functional residual capacity (FRC) were measured 2 and 6 weeks PI using a plethysmograph. Airway reactivity to aerosolized carbachol, citric acid, and histamine was determined 2 and 6 weeks PI. Most RSV and control lambs were asymptomatic after inoculation. Control lambs had significantly greater average daily weight gain by the third week after inoculation. Seven RSV lambs tested had a fourfold or greater rise in serum neutralization titers, while two control lambs had a fourfold increase. At 2 weeks PI, RSV lambs had significantly lower FRC and higher RL. At 6 weeks RL remained significantly elevated in the RSV lambs. Airway reactivity was not increased in the RSV group. This animal model is useful for studying the effects of RSV infection on lung growth and lung function over time.

Predicting arterial oxygen tension from maximum expiratory flow volume curves in cystic fibrosis.

Measurements of arterial oxygen tension (PaO2) while breathing room air, and maximum expiratory flow volume curves were performed in 34 patients with cystic fibrosis (age range 7-27 years, 24 males and 10 females). Logistic regression was performed using forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEFR), and forced expiratory flow at 75% of expired vital capacity (FEF75) to model an equation for predicting when PaO2 would be less than 55 mmHg (severe hypoxemia). Equations were modelled using one, two, three, or all four of the variables. For the univariate logistic regression, each of the four variables was a significant (P less than 0.001) predictor for severe hypoxemia. FVC was the best predictor with an R2 = 0.56, sensitivity of 100% (false negative rate = 0%), and a specificity of 88.5% (false positive rate = 27%). The model predicted that patients with an FVC less than 35% of the predicted normal were at risk of having PaO2 less than or equal to 55 mmHg. Adding FEV1, FEF75, or PEFR in various combinations to FVC made the model equation more complicated but did not add significantly to the ability to predict severe hypoxemia.

Vasodilatory effect of aerosol histamine during pulmonary vasoconstriction in unanesthetized sheep.

The effects of aerosol histamine on pulmonary vascular resistance during pulmonary vasoconstriction were studied in 12 unanesthetized sheep. Sheep were chronically instrumental with Silastic catheters in the pulmonary artery and left atrium, thermodilution Swan-Ganz catheter in the main pulmonary artery for measurement of cardiac output, and tracheostomy for delivery of hypoxic gas and/or aerosol histamine. Seven minutes of isocapnic hypoxia (FIO2 = 0.12) caused pulmonary artery pressure (PPA) to increase from 17.2 +/- 0.4 to 27.0 +/- 1.0 cm H2O (mean +/- SEM, P less than 0.05) and pulmonary vascular resistance (PVR) to increase from 3.94 +/- 0.33 to 4.71 +/- 0.38 cm H2O x L-1 x min (P less than 0.05). When sheep breathed a combination of aerosol histamine (5 mg/ml) and 12% O2, PPA rose only 21.3 +/- 1.11 cm H2O and PVR decreased to 3.51 +/- 0.31 cm H2O x L-1 x min. This was a significantly (P less than 0.05) smaller response compared to hypoxia alone. Aerosol histamine alone had to significant effect on PPA or PVR. Meclofenamate did not restore the histamine-induced loss of hypoxic vasoconstriction. Aerosol histamine significantly blunted the pulmonary vasoconstriction caused by intravenous serotonin (8 micrograms/kg/min) and intravenous prostaglandin H2-analog (0.74 microgram/kg/min). It was concluded that in the awake sheep aerosol histamine acted as a pulmonary vasodilator only in the presence of pulmonary vasoconstriction.

Effect of age on lung mechanics and airway reactivity in lambs.

We studied airway reactivity (AR) to aerosolized histamine, carbachol, and citric acid in lambs 1 mo of age to adulthood. Awake lambs were intubated and studied in a plethysmograph that measured dynamic compliance (Cdyn), resistance of the lung (RL), and functional residual capacity (FRC). Pleural pressure was measured using a Silastic balloon in the pleural space, and airway opening pressure (Pao) was measured using a catheter placed 1-2 cm distal to the nasotracheal tube. At the ages of 1, 3, 5, and 7 mo and adulthood, measurements of Cdyn, RL, and FRC were obtained in 46 sheep (22 males, 24 females). AR to carbachol, histamine, and citric acid was measured in each sheep in randomized order on three separate days by giving increasing concentrations of the drug in a noncumulative fashion. The dose that would have caused a 35% reduction in Cdyn (ED65Cdyn), a doubling of RL (ED200RL), or a 50% increase in FRC (ED150FRC) was calculated. In both males and females, base-line Cdyn increased (r = 0.81, P less than 0.01) with age, as did FRC (r = 0.87, P less than 0.01). There was no significant change in RL in either sex with age or in the group as a whole. There was a significant increase in AR to both histamine and carbachol with increasing age as measured by a decrease in ED65Cdyn (P less than 0.01 and P less than 0.05, respectively) with age. There was no significant change in AR with age as measured by RL or FRC for any of the three bronchoconstrictors tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchial responsiveness to nonantigenic bronchoconstrictors in awake sheep.

The experiments were designed to further characterize pulmonary responsiveness to nonantigenic aerosol bronchoconstrictors in unanesthetized sheep. The distribution of aerosol histamine responsiveness was described among 55 sheep. Within day reproducibility of aerosol histamine (n = 18) and carbachol (n = 8) responsiveness was studied and aerosol histamine and carbachol responsiveness were compared (n = 9). The effects of cyclooxygenase inhibition with meclofenamate (n = 7) and ibuprofen (n = 8) on pulmonary responsiveness to aerosol histamine was studied as was the effect of ibuprofen (n = 6) on pulmonary responsiveness to aerosol carbachol. A log normal unimodal distribution of pulmonary responsiveness to aerosol histamine was described. Within day pulmonary responsiveness to aerosol histamine was highly reproducible while pulmonary responsiveness to aerosol carbachol decreased slightly, but not significantly, on the second challenge. Pulmonary responsiveness to aerosol histamine correlated with pulmonary responsiveness to aerosol carbachol (r = 0.85, P less than 0.05). Meclofenamate did not significantly attenuate pulmonary responsiveness to aerosol histamine. Ibuprofen attenuated pulmonary responsiveness to aerosol histamine (P less than 0.05) but not to aerosol carbachol. These experiments supply basic information related to pulmonary responsiveness to nonantigenic bronchoconstrictors in awake sheep.