To evaluate methods used to document changes in airway function during and after exercise, we studied nine subjects with exercise-induced asthma and five subjects without asthma. Airway function was assessed from measurements of pulmonary resistance (RL) and forced expiratory vital capacity maneuvers. In the asthmatic subjects, forced expiratory volume in ...

BACKGROUND: Whether vanadium induces bronchial hyperresponsiveness and asthma in previously normal subjects is unresolved: the two reported series addressing this question both have shortcomings. OBJECTIVE: To determine the cause of cough and breathlessness in vanadium plant workers after variable periods of exposure. DESIGN: Case series of employees presenting with persistent ...

The majority of otherwise healthy subjects with chronic cervical spinal cord injury (SCI) demonstrate airway hyperresponsiveness to aerosolized methacholine or histamine. The present study was performed to determine whether ultrasonically nebulized distilled water (UNDW) induces airway hyperresponsiveness and to further elucidate potential mechanisms in this population. Fifteen subjects with SCI, ...

Prostaglandin D2 (PGD2) is the major cyclooxygenase metabolite of arachidonic acid released after stimulation of mast cells. Quantification of metabolites of PGD2 can be used as an objective indices of PGD2 production and hence mast cell activation in vivo. The aim of this thesis was to investigate the feasibility of ...

Two studies were performed to compare the persistent efficacy of doramectin and ivermectin in swine experimentally infested with Sarcoptes scabiei var. suis. In the Study 1, 84 pigs were treated with doramectin, ivermectin, or saline solution on Day 0. Pigs were then challenged with mites on Days 0, 7, 14, ...

Published evidence demonstrates successful induction and elicitation of respiratory hypersensitivity in guinea pigs by the known human respiratory allergens trimellitic anhydride (TMA) and diphenylmethane-4,4'-diisocyanate (MDI). From these data it is apparent that TMA-related respiratory hyperresponsiveness can be elicited readily in guinea pigs upon inhalation challenge with the free chemical. Despite ...

OBJECTIVE: To compare response of horses to histamine bronchoprovocation (HBP), using total respiratory resistance (Rrs) measured by forced oscillatory mechanics (FOM) with dynamic compliance (Cdyn) and pulmonary resistance (RL) measured by the esophageal balloon method. ANIMALS: 10 horses with various degrees of airway reactivity. PROCEDURE: The 2 methods for measuring ...

Previously we observed and reported that immunoglobulin E-mediated (IgE-mediated) allergy in rhesus monkeys was decreased by the administration of substance P (SP) and an allergen. We extended these studies to human subjects, giving SP and 1 allergen to subjects with reactivity to more than 1 allergen, using reactivity to a ...

BACKGROUND: Exercise-induced bronchospasm (EIB) is a common problem in children with asthma. Pretreatment with the beta2 (beta 2)-adrenoreceptor agonist albuterol is effective for preventing EIB, but is recognized as providing only short-term (2 to 3 hour) protection. OBJECTIVE: To evaluate the 12-hour efficacy and safety of single doses of 25 ...

1. In rodent models, Sephadex produces pulmonary inflammation that may be associated with bronchial hyperresponsiveness. In the present study we examined whether Sephadex-induced inflammation altered airway narrowing in pigs. 2. Twenty millilitres of 10 mg/mL Sephadex suspension was instilled twice intratracheally into anaesthetized pigs (days 1 and 7 of a ...

BACKGROUND: The pathophysiology of exercise-induced asthma is not well understood. Hypertonicity of the airway lining fluid resulting from loss of water due to hyperventilation is considered to play a role, but the precise mechanism by which hypertonicity can induce bronchoconstriction is unknown. Peptides of the endothelin (ET) family have potent ...

Forced expiratory wheezes (FEW) are common and the pathogenesis of this phenomenon might involve fluttering of the airways, but this theory has not been confirmed in patients. We report a case of a patient with FEW and a normal FEV1 that showed a bronchoscopically confirmed collapse of the trachea and ...

We analyzed the bronchial response to free running in 48 mild to moderate extrinsic asthmatics and 36 nonasthmatics and also studied the relation between the methacholine hyperresponsiveness (expressed as PC20) and the changes in peak flow (PEF) post-exercise in an asthmatic group. The highest bronchial response to exercise was observed ...

Application of continuous positive airway pressure (CPAP) in asthmatic patients decreases breathlessness (B). The effect of CPAP on induced bronchoconstriction was studied in healthy subjects. The changes in B were related to changes in lung function indices. In nine healthy volunteers, males aged 20-27 years, acute bronchoconstriction was induced by ...

BACKGROUND: Eosinophilic airway inflammation is thought to be associated with airflow limitation and airway hyperresponsiveness. METHODS: Spirometry, peak expiratory flow (PEF) measurement, histamine challenge test, and sputum induction with hypertonic saline inhalation were performed in 70 asymptomatic patients with asthma who were treated with bronchodilators or an inhaled corticosteroid (beclomethasone ...

We examined the partitioning of total lung resistance (RL) into airway resistance (Raw) and tissue resistance (Rti) in patients with mild to moderate asthma (baseline FEV1, 54 to 91% of predicted) before and after albuterol inhalation. An optimal ventilator waveform was used to measure RL and lung elastance (EL) in ...

The bronchial response to cycling and running was compared in six adult asthmatic persons. The effects of different air conditions during cycling regarding the induction of bronchoconstriction was studied. The exercise consisted of 6 minutes' work at an intensity of 80-85% of maximal heart rate. Heart rate, oxygen consumption and ...

BACKGROUND: Perception of dyspnea is poorly related to bronchoconstriction and may be influenced by distinct psychophysiologic stimuli. OBJECTIVE: This study compared the perceived psychophysiologic changes during histamine- and methacholine-induced bronchoconstriction using verbal as well as nonverbal assessment techniques. METHODS: Perception of dyspnea was studied during induced bronchoconstriction in 40 atopic ...

BACKGROUND: Asthma tends to affect mucociliary clearance, as assessed from measurements in large airways. However, there is no knowledge about clearance in the smallest airways of the tracheobronchial region in acute exacerbation of asthma. OBJECTIVE: The aim of the study was to investigate clearance from the bronchiolar region in patients ...

Control of airway function during and after exercise in asthmatics. Med. Sci. Sports Exerc., Vol. 31, No. 1 (Suppl.), pp. S4-S11, 1999. In asthmatics, airway function can be quite variable during exercise depending on the level of exercise intensity, the duration of exercise, and whether the exercise is at constant ...

In a double-blind, cross-over study, we examined the effect of inhaled budesonide (800 microgram twice daily via Turbohaler) on lung function and various markers of airway inflammation including airway responsiveness to methacholine (PC20), exhaled nitric oxide (NO), eosinophils in induced sputum, bronchoalveolar lavage (BAL), and airway biopsies from 14 patients ...

BACKGROUND: The cuffed oropharyngeal airway (COPA) is a modified Guedel airway with a cuff at its distal end and a standard 15 mm connector at its proximal end. This study was performed to determine if the COPA would offer any advantage over the laryngeal mask airway (LMA). METHODS: Eighty ASA ...

Inhalation of nitric oxide (NO) is known to dilate preconstricted airways. In asthmatics, there are large variations in the effect of NO on airway tone. One explanation of these variations may be different degrees of airway wall oedema. The effect of NO inhalation on methacholine (meth)-induced airway constriction was investigated ...

The present study examines the effect of salbutamol, a beta2-adrenoreceptor agonist, on blood ammonia levels during an incremental cycle exercise test in healthy non-asthmatic subjects. Blood ammonia levels were lower after inhalation of 400 mcg of salbutamol than after placebo during submaximal exercise: 33+/-2 micromol x l(-1) v.s. 48+/-9 micromol ...

A sine qua non of hyperresponsive airway disease in asthmatic subjects is the lack of a maximal response with increasing doses of aerosol agonist challenge. Normal subjects, however, often appear to exhibit an airway response plateau effect even when challenged with high concentrations of agonist. To investigate this question of ...

BACKGROUND: Eighty households in the Latrobe Valley, Victoria, Australia, were sampled for house-dust-mite allergen (Der p 1). Allergen levels vary greatly between houses within climate regions. The reasons for this are not well understood. METHODS: House-dust-mite allergen samples were collected on six occasions between March 1994 and February 1995. All ...

1. The thermal precipitants of asthma (exercise and hyperventilation) appear to have a unique pathogenesis that does not alter bronchial responsiveness. In the present work, we tested whether hyperpnoea interacts with other constrictor stimuli.2. To provide data on this issue, we exposed 17 subjects with asthma to isocapnic hyperventilation of ...

The aim of the present study was to examine the efficacy of low-dose inhaled budesonide (BUD) administered via Turbuhaler once or twice daily on symptoms, lung function and bronchial hyperreactivity in children with mild asthma. One hundred and sixty-three children (mean age 9.9 yrs, 56 females/107 males) with mild asthma ...

OBJECTIVE: Acute obstruction of endotracheal tubes (ETT) increases airway pressure, decreases tidal volume, increases the risk of dynamic hyperinflation by prolonging the duration of passive expiration, and prevents reliable calculation of tracheal pressure. We propose a computer-assisted method for detecting ETT obstruction during controlled mechanical ventilation. The method only requires ...

BACKGROUND: The determinants of late asthmatic responses to exercise remain unknown. It has been reported that they may develop in some adult subjects with asthma following a late asthmatic response to allergen. OBJECTIVE: We intended to corroborate this finding in children with asthma and to investigate which aspect of airway ...

We investigated airway responsiveness to mannitol, a new hyperosmolar challenge, in persons hyperresponsive to airway drying. We studied 36 asthmatic subjects, 18 to 40 yr of age, responsive to exercise (n = 23) and eucapnic hyperventilation (n = 28) defined by a 10% fall in FEV1. Fifteen subjects performed both ...

Exercise-induced bronchoconstriction (EIB) is widely prevalent in asthmatic patients. Eosinophilic airway inflammation is considered to be a major factor in the pathogenesis of asthma. However, the effects of eosinophilic airway inflammation on EIB have been elucidated insufficiently. To examine the relationship between the severity of EIB and eosinophilic inflammation, sputum ...

The structural and inflammatory changes occurring in the bronchi of asthmatics have been examined in specimens from subjects dying in status asthmaticus and from bronchial biopsies of subjects with mild asthma. Histological changes in the bronchi of asthmatics include shedding and damage of the airway surface epithelium and thickening of ...

Increased circadian variability of airway caliber is a key feature of asthmatic patients, but it has not been addressed in animal models of asthma. Furthermore, animal studies on circadian rhythmicity of airway resistance are very scanty. We used a plethysmographic method for unrestrained guinea pigs to monitor a lung resistance ...

Normal subjects develop plateaus on dose-response curves produced from inhalation challenge tests with bronchoconstricting agonists. These plateaus occur after only mild degrees of airway narrowing despite the fact that, if unloaded, maximally activated airway smooth muscle (ASM) should be able to cause airway closure. Plateaus may develop because, despite maximal ...

STUDY OBJECTIVES: Airway narrowing causes alterations in the shape of an exhaled aerosol bolus that can serve as indexes of airway changes during bronchoprovocation. We compared the sensitivities of aerosol bolus behavior and specific airway conductance (SGaw) during bronchoprovocation in normal subjects. DESIGN AND PARTICIPANTS: Fifteen normal, nonsmoking subjects were ...

The assessment of reversibility is recognized as being an essential part of the management of airways obstruction, but testing for reversibility of airways obstruction may not be useful for identifying patients with chronic obstructive pulmonary disease (COPD) who are likely to benefit from bronchodilator treatment. We studied 100 patients with ...

BACKGROUND: Although some non-asthmatic subjects with allergic rhinitis exhibit airway hyperresponsiveness and increased diurnal peak expiratory flow (PEF) variation, little is known about the critical features that determine these physiologic alterations. OBJECTIVE: In subjects with allergic rhinitis and methacholine hyperresponsiveness but no asthma symptoms, we examined whether there were features ...

The understanding of how inhaled allergens affect the asthmatic patient has changed significantly over the years. Allergen inhalation was first recognized as a cause of asthma in 1873, and the clinically important late asthmatic response (LAR) was demonstrated, albeit crudely, in 1952. Immunopathogenesis of the LAR was controversial until the ...

Ten patients with acute respiratory distress syndrome (ARDS) received in random order nitric oxide (NO) inhalation, aerosolized prostaglandin E1 (PGE1), infusion of PGE1, or no intervention. Inhalation of either aerosolized PGE1 (10 +/- 1 ng/kg/min) or NO (7 +/- 1 ppm) reduced pulmonary vascular resistance (PVR) from 158 +/- 14 ...

OBJECTIVES: To study factors affecting the occurrence of exercise induced bronchospasm (EIB) in elite runners. METHODS: Fifty eight elite runners, 79% of them belonging to Finnish national teams, volunteered. The athletes answered a questionnaire on respiratory symptoms. Skin prick tests were used to investigate atopy, and spirometry to examine lung ...

The main differences in the anatomies of the upper and lower airways are the vascular characteristics and bony surroundings of the upper airways compared with the smooth muscle component and the loose-lying situation of the lower airways. Both allergic asthma and rhinitis involve a similar process of mucosal inflammation in ...

Horses are known to acquire small airway disease (SAD), an allergen-induced naturally occurring syndrome of reversible obstructive lung disease accompanied by airway hyperresponsiveness and increased inflammatory cell numbers on bronchoalveolar lavage (BAL). This disorder has received scant attention in young racehorses. The purpose of the present report was to examine ...

Airway dilation is one of the many autonomic responses to exercise. Two neural mechanisms are believed to evoke these responses: central command and the muscle reflex. Previously, we found that activation of central command, evoked by electrical and chemical stimulation of the mesencephalic locomotor region, constricted the airways rather than ...

In some COPD patients, in contrast to those with ARDS, inhaled NO reportedly worsens hypoxemia. The issue examined in this study was whether inhaled NO improves or worsens hypoxemia in humans during bronchoconstriction induced by methacholine (MCh) nebulization. Five healthy subjects and six asthma patients were recruited, and during 80 ...

BACKGROUND: Nitric oxide (NO) plays an important part in the regulation of many physiological functions and may also be involved in several pulmonary diseases. Endogenous NO is synthesised by different isoforms of NO synthase (NOS) from L-arginine. METHODS: The effect of inhaled L-arginine 0.75 g (six normal and six asthmatic ...

To establish the effect of an aerosolized synthetic surfactant (Exosurf) on pulmonary 99mTc-diethylenetriamine pentaacetic acid (DTPA) aerosol deposition and clearance, radioaerosol studies were performed at varying times and under varying conditions after surfactant inhalation in canine lungs. Methods: Twenty-three dogs had a baseline 99mTc-DTPA study; 2 days later the study ...

The novel 5-lipoxygenase (5-LO) inhibitor, ABT-761, was investigated for its effect on exercise-induced bronchoconstriction in asthmatic subjects. The relationship between 5-LO inhibition and effects on the response of the airways to exercise was examined. In a double-blind, randomized, crossover clinical trial, 10 patients with mild to moderate persistent asthma (who ...

Lung function, studied with spirometry, nitrogen washout technique, and methacholine responsiveness, was prospectively investigated in a seven-year follow-up study of 35 laboratory animal workers (19 women and 16 men) of whom 11 were skin prick test (SPT) positive to laboratory animal allergens; five had asthma and six had rhinitis symptoms. ...

OBJECTIVE: To correlate indices of airway reactivity to bronchoalveolar lavage (BAL) fluid cytologic features in horses with a recent decline in exercise tolerance. ANIMALS: 20 actively working horses from 2 to 24 years old. PROCEDURE: Bronchoalveolar lavage fluid samples were obtained and analyzed. Forced oscillatory mechanics (1-7 Hz) technique was ...