-
Biosensors & Bioelectronics Oct 2021The methacholine challenge test is considered to be the gold standard bronchoprovocation test used to diagnose asthma, and this test is always performed in pulmonary...
The methacholine challenge test is considered to be the gold standard bronchoprovocation test used to diagnose asthma, and this test is always performed in pulmonary function labs or doctors' offices. Methacholine (MCH) acts by inducing airway tightening/bronchoconstriction, and more importantly, MCH is hydrolyzed by cholinesterase enzyme (ChE). Recently, the American Thoracic Society raised concerns about pulmonary function testing during the COVID-19 pandemic due to recently reported correlation between cholinesterase and COVID-19 pneumonia severity/mortality, and it was shown that cholinesterase levels are reduced in the acute phase of severe COVID-19 pneumonia. This work describes the microfabrication of potentiometric sensors using copper as the substrate and chemically polymerized graphene nanocomposites as the transducing layer for tracking the kinetics of MCH enzymatic degradation in real blood samples. The in-vitro estimation of the characteristic parameters of the MCH metabolism [Michaelis-Menten constant (K) and reaction velocity (V)] were found to be 241.041 μM and 56.8 μM/min, respectively. The proposed sensor is designed to be used as a companion diagnostic device that can (i) answer questions about patient eligibility to perform methacholine challenge tests, (ii) individualize/personalize medical dosing of methacholine, (iii) provide portable and inexpensive devices allowing automated readouts without the need for operator intervention (iv) recommend therapeutic interventions including intensive care during early stages and reflecting the disease state of COVID-19 pneumonia. We hope that this methacholine electrochemical sensor will help in assaying ChE activity in a "timely" manner and predict the severity and prognosis of COVID-19 to improve treatment outcomes and decrease mortality.
Topics: Biosensing Techniques; Bronchoconstrictor Agents; COVID-19; Humans; Methacholine Chloride; Pandemics; SARS-CoV-2
PubMed: 34166943
DOI: 10.1016/j.bios.2021.113439 -
Journal of Applied Physiology... Jul 2019Some subjects with asthma have ventilation defects that are resistant to bronchodilator therapy, and it is thought that these resistant defects may be due to ongoing...
Some subjects with asthma have ventilation defects that are resistant to bronchodilator therapy, and it is thought that these resistant defects may be due to ongoing inflammation or chronic airway remodeling. However, it is unclear whether regional obstruction due to bronchospasm alone persists after bronchodilator therapy. To investigate this, six young, healthy subjects, in whom inflammation and remodeling were assumed to be absent, were bronchoconstricted with a PC [the concentration of methacholine that elicits a 20% drop in forced expiratory volume in 1 s (FEV)] dose of methacholine and subsequently bronchodilated with a standard dose of albuterol on three separate occasions. Specific ventilation imaging, a proton MRI technique, was used to spatially map specific ventilation across 80% of each subject's right lung in each condition. The ratio between regional specific ventilation at baseline and after intervention was used to classify areas that had constricted. After albuterol rescue from methacholine bronchoconstriction, 12% (SD 9) of the lung was classified as constricted. Of the 12% of lung units that were classified as constricted after albuterol, approximately half [7% (SD 7)] had constricted after methacholine and failed to recover, whereas half [6% (SD 4)] had remained open after methacholine but became constricted after albuterol. The incomplete regional recovery was not reflected in the subjects' FEV measurements, which did not decrease from baseline ( = 0.97), nor was it detectable as an increase in specific ventilation heterogeneity ( = 0.78). In normal subjects bronchoconstricted with methacholine and subsequently treated with albuterol, not all regions of the healthy lung returned to their prebronchoconstricted specific ventilation after albuterol, despite full recovery of integrative lung indexes (forced expiratory volume in 1 s and specific ventilation heterogeneity). The regions that remained bronchoconstricted following albuterol were those with the highest specific ventilation at baseline, which suggests that they may have received the highest methacholine dose.
Topics: Administration, Inhalation; Adult; Albuterol; Asthma; Bronchial Provocation Tests; Bronchoconstriction; Bronchoconstrictor Agents; Bronchodilator Agents; Female; Forced Expiratory Volume; Humans; Lung; Male; Methacholine Chloride; Pulmonary Disease, Chronic Obstructive; Young Adult
PubMed: 31120808
DOI: 10.1152/japplphysiol.00912.2018 -
Respiratory Care Aug 2021The spirometric response to fast-acting bronchodilator is used clinically to diagnose asthma and in clinical research to verify its presence. However, bronchodilator...
BACKGROUND
The spirometric response to fast-acting bronchodilator is used clinically to diagnose asthma and in clinical research to verify its presence. However, bronchodilator responsiveness does not correlate with airway hyper-responsiveness measured with the direct-acting stimulus of methacholine, demonstrating that bronchodilator responsiveness is a problematic method for diagnosing asthma. The relationship between bronchodilator responsiveness and airway hyper-responsiveness assessed with indirect-acting stimuli is not known.
METHODS
Retrospectively, the spirometric responses to inhaled bronchodilator and a eucapnic voluntary hyperpnea challenge (EVH) were compared in 39 non-smoking adult subjects with asthma (26 male, 13 female; mean ± SD age 26.9 ± 7.8 y; mean ± SD body mass index 26.3 ± 4.7 kg/m). All subjects met one or both of 2 criteria: ≥ 12% and 200 mL increase in FEV after inhaled bronchodilator, and ≥ 10% decrease in FEV after an EVH challenge.
RESULTS
Overall, FEV increased by 9.9 ± 7.9% after bronchodilator (3.93 ± 0.97 to 4.28 ± 0.91 L, < .001) and decreased by 23.9 ± 15.0% after the EVH challenge (3.89 ± 0.89 to 2.96 ± 0.88 L, < .001). However, the change in FEV after bronchodilator did not correlate with the change after EVH challenge (r = 0.062, = .71). Significant bronchodilator responsiveness predicted a positive response to EVH challenge in 9 of 33 subjects (sensitivity 27%). Following EVH, the change in FEV strongly correlated with the change in FVC (FEV percent change vs FVC percent change, r = 0.831, < .001; FEV ΔL vs FVC ΔL, r = 0.799, < .001).
CONCLUSIONS
These results extend previous findings that demonstrate a lack of association between bronchodilator responsiveness and methacholine responsiveness. Given the poor concordance between the spirometric response to fast-acting bronchodilator and the EVH challenge, these findings suggest that the airway response to inhaled β-agonist must be interpreted with caution and in the context of its determinants and limitations.
Topics: Adult; Asthma; Bronchial Provocation Tests; Bronchodilator Agents; Female; Forced Expiratory Volume; Humans; Male; Methacholine Chloride; Retrospective Studies; Young Adult
PubMed: 34006592
DOI: 10.4187/respcare.08421 -
Respiratory Research Aug 2017Methacholine dose-response curves illustrate pharmacologic bronchoprotection against methacholine-induced airway hyperresponsiveness and can be used to quantitate... (Comparative Study)
Comparative Study Randomized Controlled Trial
The effect of glycopyrronium and indacaterol, as monotherapy and in combination, on the methacholine dose-response curve of mild asthmatics: a randomized three-way crossover study.
BACKGROUND
Methacholine dose-response curves illustrate pharmacologic bronchoprotection against methacholine-induced airway hyperresponsiveness and can be used to quantitate changes in airway sensitivity (position), reactivity (slope), and maximal responsiveness following drug administration. Our objective was to determine the influence of single-dose glycopyrronium (long-acting muscarinic antagonist) and indacaterol (ultra-long acting β agonist), as monotherapy and in combination, on the methacholine dose-response curve of mild asthmatics and to compare these findings with a non-asthmatic control curve.
METHODS
This was a randomized, double blind, double dummy, three-way crossover study. For asthmatic participants (n = 14), each treatment arm included a baseline methacholine challenge, drug administration, and repeat methacholine challenges at 1, 24, and 48 h. Non-asthmatic control participants (n = 15) underwent a single methacholine challenge and did not receive any study treatment. Methacholine dose-response curves were graphed as the percent fall in forced expiratory volume in 1 s (FEV) for each methacholine concentration administered. Best-fit curves were then generated. Differences in airway reactivity were calculated through linear regression. Changes in airway sensitivity were assessed as the shift in the provocative concentration of methacholine causing a 20% fall in FEV.
RESULTS
Compared to baseline, all treatments significantly reduced airway sensitivity to methacholine at 1 h post-dose (indacaterol ~1.5 doubling concentrations; glycopyrronium ~5 doubling concentrations; combination ~5 doubling concentrations). Bronchoprotection at 24 and 48 h remained significant with glycopyrronium and combination therapy only. Airway reactivity was not influenced by indacaterol whereas glycopyrronium significantly reduced airway reactivity at all time-points (p = 0.003-0.027). The combination significantly decreased slope at 1 (p = 0.021) and 24 (p = 0.039) hours only. The non-asthmatic control and 1-h glycopyrronium curves are nearly identical. Only the non-asthmatic control and 1-h post-combination therapy curves appeared to generate a true response plateau (three data points within 5%), which occurred at a 14% fall in FEV.
CONCLUSIONS
Methacholine dose-response curves differentiate the bronchoprotective mechanisms triggered by different classes of asthma medications. Assessment of bronchoprotection using methacholine dose-response curves may be useful during clinical development of respiratory medications when performing superiority, equivalence, or non-inferiority trials.
TRIAL REGISTRATION
clinicaltrials.gov ( NCT02953041 ). Retrospectively registered on October 24th 2016.
Topics: Adolescent; Adrenergic beta-2 Receptor Agonists; Adult; Aged; Asthma; Bronchial Provocation Tests; Bronchoconstrictor Agents; Bronchodilator Agents; Cross-Over Studies; Double-Blind Method; Drug Combinations; Female; Forced Expiratory Volume; Glycopyrrolate; Humans; Indans; Lung; Male; Methacholine Chloride; Middle Aged; Muscarinic Antagonists; Quinolones; Saskatchewan; Severity of Illness Index; Time Factors; Treatment Outcome; Vital Capacity; Young Adult
PubMed: 28768531
DOI: 10.1186/s12931-017-0628-4 -
Respiratory Physiology & Neurobiology Mar 2020Nocturnal worsening of asthma may be due to reduced lung volumes and fewer sigh breaths, which have been shown to increase airway resistance and bronchoreactivity. We... (Clinical Trial)
Clinical Trial
Nocturnal worsening of asthma may be due to reduced lung volumes and fewer sigh breaths, which have been shown to increase airway resistance and bronchoreactivity. We hypothesized that mimicking deep inspiration using nocturnal mechanical support would improve symptoms in patients with asthma. Subjects with asthma underwent usual care and bilevel positive airway pressure (PAP) therapy for 4 weeks, separated by 4 weeks, and methacholine challenge (PC) and subjective assessments. 13 patients with asthma alone and 8 with asthma + OSA completed the protocol. Change in bronchoreactivity (ratio of Post/Pre PC) was not significantly different during usual care and bilevel PAP [0.86 (IQR 0.19, 1.82) vs 0.94 (IQR 0.56, 2.5), p = 0.88], nor was the change in Asthma Control Test different: 0.1 ± 2.2 vs. -0.2 ± 2.9, p = 0.79, respectively. Bilevel PAP therapy for four weeks did not improve subjective or objective measures of asthma severity in patients with asthma or those with asthma and OSA, although there was heterogeneity in response.
Topics: Adult; Asthma; Bronchial Provocation Tests; Bronchoconstrictor Agents; Continuous Positive Airway Pressure; Cross-Over Studies; Female; Humans; Lung Volume Measurements; Male; Methacholine Chloride; Middle Aged; Outcome Assessment, Health Care; Sleep Apnea, Obstructive
PubMed: 31805396
DOI: 10.1016/j.resp.2019.103355 -
Pulmonary Pharmacology & Therapeutics Feb 2020Methacholine challenges have been used in clinical trials to assess therapeutic effects and potential adverse reactions of interventions on pulmonary function in a... (Clinical Trial)
Clinical Trial
BACKGROUND
Methacholine challenges have been used in clinical trials to assess therapeutic effects and potential adverse reactions of interventions on pulmonary function in a sensitive population, such as in subjects with asthma. Here, we evaluate the variability of the methacholine challenge recovery model, and compare the results obtained for both incremental and bolus challenge methods.
METHODS
The extent, time course and variability of change in forced expiratory volume in 1 s (FEV) following repeated methacholine challenges in subjects with mild asthma were investigated in an open-label, four-period, fixed-sequence, two-method, replicate crossover study. At Visits 1 and 2, subjects underwent an incremental challenge using doubling doses of methacholine until a ≥20% decrease in FEV was observed; at Visits 3 and 4, subjects underwent a bolus challenge, inhaling a single dose of methacholine calculated from the cumulative dose established during Visit 1.
RESULTS
A total of 19 subjects were included in the study. Both the mean FEV area under the curve (FEV AUC) and mean maximum reductions in FEV (absolute and relative) 120 min post-challenge values were higher for the incremental challenges than the bolus challenges, with no reported difference between repetitions of the same methodology. FEV AUC decrease 120 min post challenge demonstrated an intra-subject coefficient of variation (CV) of 47.2% (incremental) and 78.3% (bolus), suggesting considerable between-visit variability. The mean absolute, and similarly relative, maximum reductions in FEV compared with post-diluent baseline values demonstrated lower intra-subject variability (incremental 21.16%, bolus 40.67%) than the FEV AUC-based endpoint. There was a trend towards faster recovery following the bolus challenge than with the incremental challenge. The provocative dose of methacholine inducing a ≥20% decrease in FEV resulted in a between-group mean difference of 27.20% in the incremental challenge periods, with a high intra-subject CV of 80.64%, demonstrating considerable variability.
CONCLUSION
Maximum reduction in FEV had the lowest variability. There was little difference between repetitions of the same methodology, as indicated by overlapping confidence intervals. There was a trend towards faster recovery following bolus challenge than with the incremental challenge. The results of this trial could be of value when designing future clinical trials using the methacholine challenge methodology.
Topics: Administration, Inhalation; Adult; Aged; Aged, 80 and over; Anti-Asthmatic Agents; Asthma; Cross-Over Studies; Drug Delivery Systems; Female; Forced Expiratory Volume; Humans; Lung; Male; Methacholine Chloride; Middle Aged
PubMed: 31843704
DOI: 10.1016/j.pupt.2019.101876 -
Pulmonary Pharmacology & Therapeutics Dec 2014This study presents an animal model of native airway hyperresponsiveness (AHR). AHR is a fundamental aspect of asthma and reflects an abnormal response characterized by...
BACKGROUND
This study presents an animal model of native airway hyperresponsiveness (AHR). AHR is a fundamental aspect of asthma and reflects an abnormal response characterized by airway narrowing following exposure to a wide variety of non-immunological stimuli. Undescended testis (UDT) is one of the most common male congenital anomalies. The orl rat is a Long Evans substrain with inherited UDT. Since boys born with congenital UDT are more likely to manifest asthma symptoms, the main aim of this study was to investigate the alternative hypothesis that orl rats have greater AHR to a methacholine aerosol challenge than wild type rats.
METHODS
Long Evans wild type (n = 9) and orl (n = 13) rats were anesthetized, tracheostomized, and mechanically ventilated at 4 weeks of age. Escalating concentrations of inhaled methacholine were delivered. The methacholine potency and efficacy in the strains were measured. Respiratory resistance was the primary endpoint. After the final methacholine aerosol challenge, the short-acting β2-adrenoceptor agonist albuterol was administered as an aerosol and lung/diaphragm tissues were assayed for interleukin (IL)-4, IL-6, and tumor necrosis factor (TNF)-α. Histological and histomorphometrical analyses were performed.
RESULTS
The methacholine concentration-response curve in the orl group indicated increased sensitivity, hyperreactivity, and exaggerated maximal response in comparison with the wild type group, indicating that orl rats had abnormally greater AHR responses to methacholine. Histological findings in orl rats showed the presence of eosinophils, unlike wild type rats. β2-Adrenoceptor agonist intervention resulted in up-regulation of IL-4 diaphragmatic levels and down-regulation of IL-4 and IL-6 in the lungs of orl rats.
CONCLUSION
orl rats had greater AHR than wild type rats during methacholine challenge, with higher IL-4 levels in diaphragmatic tissue homogenates. Positive immunostaining for IL-4 was detected in lung and diaphragmatic tissue in both strains. This model offers advantages over other pre-clinical murine models for studying potential mechanistic links between cryptorchidism and asthma. This animal model may be useful for further testing of compounds/therapeutics options for treating AHR.
Topics: Administration, Inhalation; Albuterol; Animals; Anti-Asthmatic Agents; Asthma; Bronchoconstrictor Agents; Cryptorchidism; Disease Models, Animal; Dose-Response Relationship, Drug; Interleukin-4; Interleukin-6; Lung; Male; Methacholine Chloride; Rats, Long-Evans; Tumor Necrosis Factor-alpha
PubMed: 25218882
DOI: 10.1016/j.pupt.2014.09.001 -
American Journal of Physiology. Lung... Jun 2017Pompe disease is an autosomal recessive disorder caused by a deficiency of acid α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen....
Pompe disease is an autosomal recessive disorder caused by a deficiency of acid α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen. Deficiency of GAA leads to systemic glycogen accumulation in the lysosomes of skeletal muscle, motor neurons, and smooth muscle. Skeletal muscle and motor neuron pathology are known to contribute to respiratory insufficiency in Pompe disease, but the role of airway pathology has not been evaluated. Here we propose that GAA enzyme deficiency disrupts the function of the trachea and bronchi and this lower airway pathology contributes to respiratory insufficiency in Pompe disease. Using an established mouse model of Pompe disease, the mouse, we compared histology, pulmonary mechanics, airway smooth muscle (ASM) function, and calcium signaling between and age-matched wild-type (WT) mice. Lysosomal glycogen accumulation was observed in the smooth muscle of both the bronchi and the trachea in but not WT mice. Furthermore, mice had hyporesponsive airway resistance and bronchial ring contraction to the bronchoconstrictive agents methacholine (MCh) and potassium chloride (KCl) and to a bronchodilator (albuterol). Finally, calcium signaling during bronchiolar smooth muscle contraction was impaired in mice indicating impaired extracellular calcium influx. We conclude that GAA enzyme deficiency leads to glycogen accumulation in the trachea and bronchi and impairs the ability of lower ASM to regulate calcium and respond appropriately to bronchodilator or constrictors. Accordingly, ASM dysfunction may contribute to respiratory impairments in Pompe disease.
Topics: Albuterol; Animals; Bronchi; Calcium Signaling; Extracellular Space; Glycogen; Glycogen Storage Disease Type II; Lung; Methacholine Chloride; Mice; Muscle Contraction; Muscle, Skeletal; Potassium Chloride; Trachea; alpha-Glucosidases
PubMed: 28336814
DOI: 10.1152/ajplung.00568.2016 -
Journal of Applied Physiology... Jun 2018It is suggested that the frequent strain the airways undergo in asthma because of repeated airway smooth muscle (ASM)-mediated constrictions contributes to airway wall...
It is suggested that the frequent strain the airways undergo in asthma because of repeated airway smooth muscle (ASM)-mediated constrictions contributes to airway wall remodeling. However, the effects of repeated constrictions on airway remodeling, as well as the ensuing impact of this presumptive remodeling on respiratory mechanics, have never been investigated in subjects without asthma. In this study, we set out to determine whether repeated constrictions lead to features that are reminiscent of asthma in mice without asthma. BALB/c mice were subjected to a 30-min constriction elicited by aerosolized methacholine every other day over 6 wk. Forty-eight hours after the last constriction, the mechanics of the respiratory system was evaluated at baseline and in response to incremental doses of nebulized methacholine with the flexiVent. The whole-lung lavages, the tracheas, and the lungs were also collected to evaluate inflammation, the contractile capacity of ASM, and the structural components of the airway wall, respectively. The resistance and the compliance of the respiratory system, as well as the Newtonian resistance and the resistive and elastic properties of the lung tissue, were not affected by repeated constrictions, both at baseline and in response to methacholine. All the other examined features also remained unaltered, except the number of goblet cells in the epithelium and the number of macrophages in the whole-lung lavages, which both increased with repeated constrictions. This study demonstrates that, despite causing goblet cell hyperplasia and a mild macrophagic inflammation, repeated constrictions with methacholine do not lead to structural changes that adversely impact the physiology. NEW & NOTEWORTHY Repeated airway constrictions led to signs of remodeling that are typically observed in asthma, which neither altered respiratory mechanics nor the contractile capacity of airway smooth muscle. These findings shed light on a debate between those claiming that constrictions induce remodeling and those convinced that methacholine challenges are harmless. Insofar as our results with mice relate to humans, the findings indicate that repeated challenges with methacholine can be performed safely.
Topics: Airway Remodeling; Animals; Bronchoconstriction; Female; Inflammation; Methacholine Chloride; Mice, Inbred BALB C; Muscle, Smooth
PubMed: 29470147
DOI: 10.1152/japplphysiol.01073.2017 -
The European Respiratory Journal Dec 2019There are few data on the usefulness of different tests to diagnose asthma in children.
INTRODUCTION
There are few data on the usefulness of different tests to diagnose asthma in children.
AIM
We assessed the contribution of a detailed history and a variety of diagnostic tests for diagnosing asthma in children.
METHODS
We studied children aged 6-16 years referred consecutively for evaluation of suspected asthma to two pulmonary outpatient clinics. Symptoms were assessed by parental questionnaire. The clinical evaluation included skin-prick tests, measurement of exhaled nitric oxide fraction ( ), spirometry, bronchodilator reversibility and bronchial provocation tests (BPT) by exercise, methacholine and mannitol. Asthma was diagnosed by the physicians at the end of the visit. We assessed diagnostic accuracy of symptoms and tests by calculating sensitivity, specificity, positive and negative predictive values and area under the curve (AUC).
RESULTS
Of the 111 participants, 80 (72%) were diagnosed with asthma. The combined sensitivity and specificity was highest for reported frequent wheeze (more than three attacks per year) (sensitivity 0.44, specificity 0.90), awakening due to wheeze (0.41, 0.90) and wheeze triggered by pollen (0.46, 0.83) or by pets (0.29, 0.99). Of the diagnostic tests, the AUC was highest for measurement (0.80) and BPT by methacholine (0.81) or exercise (0.74), and lowest for forced expiratory volume in 1 s (FEV) (0.62) and FEV/forced vital capacity ratio (0.66), assessed by spirometry.
CONCLUSION
This study suggests that specific questions about triggers and severity of wheeze, measurement of and BPT by methacholine or exercise contribute more to the diagnosis of asthma in school-aged children than spirometry, bronchodilator reversibility and skin-prick tests.
Topics: Adolescent; Asthma; Bronchial Provocation Tests; Bronchodilator Agents; Child; Exhalation; Female; Forced Expiratory Volume; Humans; Male; Mannitol; Medical History Taking; Methacholine Chloride; Nitric Oxide; Pollen; Respiratory Sounds; Skin Tests; Spirometry; Vital Capacity
PubMed: 31515409
DOI: 10.1183/13993003.01326-2019